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Development of idler for measuring indentation rolling resistance in pipe conveyor belts
Journal Pre-proofs Development of idler for measuring indentation rolling resistance in pipe conveyor belts Leonardo dos Santos e Santos, Paulo Roberto Campos Flexa Ribeiro Filho, Emanuel Negrão Macêdo PII: DOI: Reference:
S0263-2241(19)31280-1 https://doi.org/10.1016/j.measurement.2019.107413 MEASUR 107413
To appear in:
Measurement
Received Date: Revised Date: Accepted Date:
27 October 2019 2 December 2019 16 December 2019
Please cite this article as: L. dos Santos e Santos, P. Roberto Campos Flexa Ribeiro Filho, E. Negrão Macêdo, Development of idler for measuring indentation rolling resistance in pipe conveyor belts, Measurement (2019), doi: https://doi.org/10.1016/j.measurement.2019.107413
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Title Development of idler for measuring indentation rolling resistance in pipe conveyor belts
Authors M.Eng. Leonardo dos Santos e Santos, orcid: 0000 0002 2038 1184 M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho, orcid: 0000 0002 6066 1041 D.Sc. Emanuel Negrão Macêdo, orcid: 0000 0002 4652 8316
Abstract The major contribution to energy consumption in a pipe conveyor is from indentation rolling resistance, which is also called viscoelastic resistance. Reproducing the effects of actual operating conditions is a challenge for direct measurements, as samples from the original belt are currently used for small-scale laboratory testing. This paper presents a low-cost measuring idler developed for indentation data acquisition from pipe conveyors under different conditions. Using a calibration support and an electronic module for data storage, it was possible to analyze the belt speed, temperature, humidity, and vertical, horizontal, and rotational loads. The correlation coefficients obtained for the belt speed and vertical loading measurements were, respectively, as follows: 0.998927314 for 340 samples, and 0.777221023 for 600 samples. The indentation rolling resistance values decreases as the belt filling degree increased, and the production cost was feasible for industrial production. Keywords 1.Indentation 2. Measuring idler 3. Pipe conveyor. 1.
Introduction
Pipe conveyors are an advantageous alternative to the conventional belt conveyor as they circumvent the technical limitations of the latter [1,2,3,4,5,6,7]. A pipe conveyor comprises a conveyor belt enclosed by hexagonal panels, and a completely closed tube is thus obtained owing to the overlapping of the belt edges. In addition, to preventing interactions between the handled material and the environment, pipe conveyors have great flexibility in geometry in the case of vertical and horizontal curvatures [7]. As compared to a conventional belt conveyor, a tubular one consumes, on average, twice the energy for the same distance [1]. The belt rolling resistance distributed at each idler along the conveyor is the sum of the forces due to (i) the rotational inertia of the idlers, (ii) material flexural deformation, (iii) belt flexural deformation, and (iv) idlers indentation in the belt. The indentation rolling resistance formed in a pipe belt conveyor is larger than that in a conventional one [7]. Furthermore, in the case of a conventional belt, this force corresponds to between 50 and 60% of the total equipment energy consumption [7,8,9,10,11,12,13]. In addition, the belt costs can comprise up to 70% of the equipment costs [8]. Rubber composite materials are viscoelastic and, therefore, exhibit variations in their properties between those of elastic solids and viscous liquids depending on the experimental conditions [14]. As the belt moves over a conveyor idler, the pressure exerted at the initial contact area increases via compression, and the pressure under the final contact area is reduced owing to material hysteresis. The rubber back cover expands more slowly than it is compressed, thus
resulting in the formation of an asymmetrical stress distribution. This variation in tension generates a motion reaction force called indentation rolling resistance or viscoelastic resistance [14,15,16,7]. There exist different methods for establishing indentation values. Some of them are as follows: (i) the analytical methods of Lanchmann, 1954; May et al., 1959; Hunter, 1961; Morland, 1962; Spaans, 1978; Jonkers, 1980; Johnson, 1985; Lodewijks, 1995; Qiu, 2006; Rudolphi, 2005; Lu and Lin, 2016 [17]; (ii) Wheeler's finite element method (FEM) and Qui's boundary element method (BEM), which is an offshoot of the analytical method; and (iii) direct measurement methods such as the inclined plane experiment [9], hydraulic actuator [18], and the Conveyor Equipment Manufacturers Association (CEMA) two-pulley test machine [9,19], which the DIN EN 16974: 2016 and AS 1334.13: 2017 standards apply [20,21]. Direct indentation measurement presents practical challenges in separating the contribution of the belt back cover from other losses as well as in evaluating the effect of the conveyor design variables such as tension, speed, and material loading. Reproducing the effects of actual operating conditions also presents a challenge in obtaining direct measurements, as samples from the original belt are used for small-scale laboratory testing [22,20,21]. The continuous monitoring of the forces of the belt interaction with the conveyor idlers is a key factor affecting the operational reliability of pipe conveyors [23] as the transverse stiffness of the belt changes with the operating time as a function of the fatigue caused in the belt opening and closing movements. These movements are performed twice in each belt revolution, i.e., in the transition regions from pipe shape to open form. Given the importance of tubular conveyors in industrial bulk handling processes and the impact of indentation on the design of this type of equipment, it is necessary to develop devices for measuring the opposing force to the belt rolling, which would benefit plant operation, designing of new equipment, and development of belt compounds. In the case of existing equipment, it is possible to establish end-of-life predictors as well as safeguards that minimize operational risks. In the case of new projects, it is possible to apply finer mathematical formulations and create standards for pipe conveyor designs. This paper presents the development of a low-cost method for measuring pipe-belt-conveyor indentation data by (i) designing, fabricating, and assembling a load idler having an operational capacity in accordance with ABNT NBR 6678: 2018 – Continuous conveyors, belt conveyors Idlers - Design, selection and standardization [24]; (ii) dimensioning, installing, and calibrating strain gauges and speed sensors that are appropriately arranged on the measuring idler shaft for the acquisition of velocity and strain data in the vertical and horizontal planes; (iii) parameterizing and programming the prototyping platform for processing deformation and velocity data as well as transferring data to the computer for storage, analysis, and reporting. 2.
Material and methods
For the development of the indentation measurement methodology for a tubular belt conveyor, a commissioned and operational equipment was selected for determining the idler to be used, as shown in figure 1. The basic design data of the selected conveyor is presented in table 1.
Figure 1 – Selected pipe conveyor and hexagonal panels. Table 1 – Design data of selected tubular conveyor. Conveyor Technical Data Design capacity Carried material Belt speed Pipe diameter Drive power Developed Length Horizontal curves Idlers (hexagonal panels)
t/h m/s mm kW m und und
1,000 bituminous coal 5.1 375 3 x 550 4,283 14 23,349
The basic data of a typical load idler of the selected pipe conveyor is presented in Table 2. Table 2 – Idler technical data. Idler Technical Data Idler diameter Shaft diameter Idler width Maximum eccentricity Material Fastening type Bearing type 1.
mm mm mm mm -
165.1 30 345 0.6 Carbon steel Screw fastening Ball bearing
Defining Measuring Idler Characteristics
The first step in defining the construction characteristics of the measuring idler was the selection of interest parameters in the indentation measurement. Table 3 presents the selected parameters and their descriptions. Table 3 – Parameters selected for measuring idler. Parameter
Description
Horizontal force Vertical force Torque Speed
Indentation resistance measurement Evaluation of effect on indentation Rotational resistance measurement Evaluation of effect on indentation
Temperature Humidity Date and time Memory
Evaluation of effect on indentation Evaluation of effect on indentation Database Database
The geometry of the measuring idler shaft was defined in order to allow transducers and electronics to acquire these parameters while being embedded in the idler. Thus, it was necessary to anticipate the requirement for the inclusion of a prototyping platform in the idler and consider openings in the shaft, both for the connection of electronic cabling and the renewal of air inside the idler, as it is temperature and humidity data collection required.
Figure 2 –Indentation rolling resistance idler. Four longitudinal slots were thus included in the design. These were designed to mitigate the influences of stresses on orthogonal planes. In the shaft central part, four larger openings were considered to allow the application of linear extensometers. At the shaft ends, two opposite openings were arranged for positioning shear strain gauges in order to measure the rotational forces due to the bearings.
Figure 3 – Exploded view of indentation measuring idler. 2.
Detailing of mechanical parts
With the conceptual data defined, the mechanical assembly details were then defined. The material selected for the shaft was AISI 304 stainless steel. The material selected for the bearings and idler housing was AISI 1020 carbon steel. The fasteners for the electronic circuit, pulse-count sensor fastener, and toothed crown were fabricated from ABS (acrylonitrile butadiene styrene) as it is a lightweight, inexpensive material that can be used in 3D printers. Deep-groove ball bearings 6306 were selected, to obtain the same characteristics as those of the typical pipe conveyor idler, while using 2RS seal to facilitate mounting without the requirement for additional sealing. The retaining rings to hold the bearings in the mounting positions have been specified as SAE 1070 DIN 471 carbon steel. Each bearing is secured using 10 AISI-304-stainlesssteel Allen DIN 912 head screws.
Figure 4 – Indentation rolling resistance idler assembly.
3.
Details of electronics
The electronic components required to collect each of the interest variables were specified. The prototyping platform was first selected: the low-cost, open-source Arduino Mega. For the horizontal, vertical, and rotational force readings, four Avia Semiconductor model HX711 plates were selected for reading strain gauges. No additional filters were used for conditioning the extensometer signals. The pulse-count sensor selected was YwRobot's IR Switch. To acquire temperature and humidity data, Aosong module AM2302 was selected. For the timestamp, the Maxim Integrated DS3231 Real Time Clock module was selected. For storing the collected data, the Catalex Micro SD Adapter module with 5-V direct interface and support for memory cards was selected. Figure 5 presents an overview of the electronic components.
Figure 5 – Electronics for measuring idler. The other components selected were eight linear precision strain gauges for measuring the horizontal and vertical strains, and four half-bridge shear strain gauges for measuring the rotational strain (350±0.1 Ohms). The complete Wheatstone bridge configuration was used for the strain measurements.
Figure 6 – Electronics used in measurement idler shaft. 4.
Details of calibration support
A calibration support was developed for an application of known loading and in the selected planes. The support comprised a round bar of AISI-304 stainless steel. The following materials have been specified for the other accessories: one 300-kg digital hook-type hanging scale MNCSM from Mini Crane; and one AISI-316 stainless-steel swivel shackle, which has been modified to include a DIN 933 hex head screw to pull the balance and subject the idler to known loads.
Figure 7 – Calibrating of indentation rolling resistance idler. 5.
Checking of loaded components
Verification was performed via FEM using computational modeling as well as a buckling analysis for the calibration support. The measuring idler was also evaluated in relation to the different aspects considered in ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers - Design [24]. The measuring idler was approved in terms of this various aspects, and it was thus considered to be suitable for use in the selected pipe conveyor, which made the methodology feasible. Table 4 presents the evaluation of the measuring idler against the standard criteria. Table 4 – Measurement idler analysis with respect to considerations of ABNT 6678:2018 [24].
Item 8.6.1 8.6.2 8.7.2 8.9.3 9.3.5 9.3.6 9.6.1
Description
Criteria
Reference Value
Measurement Idler
50
49.8
4,599 26,700 600 13.4 4.25 0.6
4,599 29,600 590 11.4 4.7625 0.6
Distance from bearing center to idler mm (maximum) attachment point Allowable load on idlers Bearing dynamic load (6306) Idler rotating speed Idler mass Minimum wall thickness Eccentricity tolerance
N (minimum) N (minimum) rpm (maximum) kg (maximum) mm(minimum) mm (maximum)
Source: Adapted from [24].
Figure 8 – Collecting conveyor data using indentation rolling resistance idler. 3.
Theory and Calculations
In scientific production, an analytical formula was developed [25] based on a simplification of Rudolphi's formulations [10] and the application of Jonkers' formulations [26] as a reference for this purpose, as shown in Eq. (1): 2𝐸0 𝑉𝑏2𝑃 1 3 3 𝐹ℎ = (𝜏𝜆) 2 ― 𝜏²𝜆² 4 3 𝑅2 𝑃𝑅ℎ 𝑅 𝑉 𝑏𝑃
(
) ( )
1 3
(1)
𝜆=
𝐸1
(2)
𝐸0
The constants related to the viscoelastic material parameters are separated, and the analytical formula is presented for the indentation force [25]:
𝐹ℎ = 𝐴
𝑉 𝑏𝑃 𝑅2
―𝐵
𝑉𝑏2𝑃 𝑅2
1 3
( ) 1 𝑃𝑅ℎ
(3)
Being: 𝐹ℎ = 𝐼𝑛𝑑𝑒𝑛𝑡𝑎𝑡𝑖𝑜𝑛 𝑟𝑜𝑙𝑙𝑖𝑛𝑔 𝑟𝑒𝑠𝑖𝑠𝑛𝑡𝑎𝑐𝑒 𝑖𝑛 𝑁/𝑚; 𝑃 = 𝑉𝑒𝑟𝑡𝑖𝑐𝑎𝑙 𝑙𝑜𝑎𝑑 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑏𝑒𝑙𝑡 𝑎𝑛𝑑 𝑖𝑑𝑙𝑒𝑟 𝑖𝑛 𝑁/𝑚; ℎ = 𝐵𝑒𝑙𝑡 𝑏𝑎𝑐𝑘 𝑐𝑜𝑣𝑒𝑟 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑖𝑛 𝑚; 𝑉𝑏 = 𝐵𝑒𝑙𝑡 𝑠𝑝𝑒𝑒𝑑 𝑖𝑛 𝑚/𝑠; 𝑅 = 𝐼𝑑𝑙𝑒𝑟 𝑟𝑎𝑑𝑖𝑢𝑠 𝑖𝑛 𝑚; 𝐴 𝑎𝑛𝑑 𝐵 = 𝑀𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡𝑠 𝑑𝑒𝑝𝑒𝑛𝑑𝑖𝑛𝑔 𝑜𝑛 𝜏, 𝐸0 𝑎𝑛𝑑 𝐸1; 𝐸0 = 𝐸𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 𝑚𝑜𝑑𝑢𝑙𝑢𝑠 𝑖𝑛 𝑃𝑎; 𝐸1 = 𝑀𝑜𝑑𝑒𝑙′𝑠 𝑒𝑙𝑎𝑠𝑡𝑖𝑐 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 𝑖𝑛 𝑃𝑎; 𝜏 = 𝑅𝑒𝑙𝑎𝑥𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 𝑖𝑛 𝑠; This analytical formula reflects the influence of common working conditions such as vertical loading, belt speed, idler diameter, and belt back cover thickness [25]. According to [10], the compounds used in the belt back cover are highly dependent on the temperature and loading frequency. [27] presented a reduction in the indentation factor with increasing temperature for a variety of return covers, including low-rolling-resistance belts. The belt carcass also has a significant influence on the indentation rolling resistance, as experiments show that textile-reinforced belts have higher indentation values than steel-cordreinforced belts. In addition, belts having smaller diameters on wire ropes have lower indentation values [28]. For the calculation of the indentation factor, considering the contact of the pipe belt with the surface of the conveyor idler, Eq. (4) is used [7]:
( ) 6
𝑓𝑖𝑛𝑑 =
∑𝐹
𝑟𝑛
𝑛=1
1
(𝑚𝑚′ +
𝑚𝑏′) 𝑔 𝑙′
where: 𝑓𝑖𝑛𝑑 = 𝐼𝑛𝑑𝑒𝑛𝑡𝑎𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 𝑓𝑜𝑟 𝑝𝑖𝑝𝑒 𝑐𝑜𝑛𝑣𝑒𝑦𝑜𝑟, 𝑤ℎ𝑖𝑐ℎ 𝑖𝑠 𝑑𝑖𝑚𝑒𝑛𝑠𝑖𝑜𝑛𝑙𝑒𝑠𝑠;
(4)
𝑛 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑖𝑑𝑙𝑒𝑟𝑠 𝑓𝑜𝑟 𝑎 𝑔𝑖𝑣𝑒𝑛 𝑝𝑎𝑛𝑒𝑙; 𝑚𝑚′ = 𝐿𝑖𝑛𝑒𝑎𝑟 𝑚𝑎𝑠𝑠 𝑐𝑎𝑟𝑟𝑖𝑒𝑑 𝑖𝑛 𝑘𝑔/𝑚; 𝑚′𝑏 = 𝐵𝑒𝑙 𝑙𝑖𝑛𝑒𝑎𝑟 𝑚𝑎𝑠𝑠 𝑖𝑛 𝑘𝑔/𝑚; 𝑔 = 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑚/𝑠²; 𝑙′ = 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑝𝑎𝑛𝑒𝑙𝑠 𝑖𝑛 𝑚; From Eq. (4), it can be concluded that the increase in the pipe conveyor filling degree causes a reduction in the indentation factor [7]. The stiffness of the belt remains the same; however, as the load increases, the overall friction factor decreases as a function of the carried-material flexural strength. According to [29], the belt transverse stiffness is an important variable in the design of belts in pipe conveyors: if the belt diameter is reduced or if the belt does not touch all the idlers on the panel, it may result in a twist effect or overlap rotation. These situations are undesirable and can result in material leakage, premature damage to the overlap outer edge, collapse of the tubular formation, and difficulty in opening in the discharge drum: these situations can cause major problems for the user, with impacts on availability and operational safety. In addition, according to [29], the transverse stiffness of the belt decreases as the number of cycles increases as a function of the repetitive bending movement; thus, the indentation force on the idlers is reduced. By analyzing Eq. (4), it is also possible to evaluate the effect of the distance between the conveyor panels on the indentation factor. Increasing the spacing between panels results in a reduction in the indentation rolling resistance. According to [28], a reduction in the number of times the belt is flexed between the panels along the conveyor reduces the belt and material flexural strengths. 1.
Influence of variables on indentation values
The indentation value of a given belt conveyor is influenced by several factors, including the operating conditions and material characteristics employed—particularly in the belt and idler design. Table 5 presents the effects of the main variables under study. When not indicated, it can be considered that there is an effect on both the conventional and pipe conveyors. Table 5 – Effect of operating conditions on indentation value. Variable Belt speed Vertical load (conventional) Back cover thickness Idler radius Temperature Panel spacing Transverse stiffness (tubular) Number of cycles (tubular) Filling degree (tubular) Linear belt mass (tubular)
Variable behavior
Effect on indentation
↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑
↑ ↑ ↓ ↓ ↓ ↓ ↑ ↓ ↓ ↓
Source: Adapted from [29,25,7,27,28] 4.
Results
In order to calibrate the shear strain gauges, the measuring idler shaft was mounted on the calibration support, and a special tool was developed to apply known and certified masses, as illustrated in Figure 9.
Figure 9 - Support for applying rotational loads. Known masses of 200 g, 500 g, 1000 g, and 2000 g were applied to the special tool attached to the idler shaft, and the calibration factors were obtained through an auxiliary program developed for the calibration process.
Figure 10 - Application of standard weights of 1000 g and 2000 g, respectively. With the calibration factors identified during application of the standard masses of 2000 g, records were made to verify the differences in measurement, as shown in Table 6. Table 6 - Rotational loading on measuring idler shaft. Description
Standard (g)
Right (g)
Left (g)
Samples
Deviation (g)
Modules tare Modules tare
0 0 2,000
0.113 2,119.328
0.323 -
379 379 323
0.113 0.323 119.328
Load application
Load application
2,000
-
2,182.464
323
182.464
Zero values were averaged for 379 samples, and the difference from the expected value was 0.113 g for the right-hand-side measurements and 0.323 g for the left-hand-side measurements. A standard weight of 2000 g was applied on each support of the measuring idler shaft, and 323 samples were obtained; the difference from the expected value was 119.328 g for the right-side measurement and 182.464 g for the measurement left side. The percentage change obtained in relation to the largest applied load of 2000 g was 5.96% for the right-hand-side measurement and 9.12% for the left-hand-side measurement. This equals 7.54% for the total load of 4000 g. After mounting the measuring idler on the calibrating support, it was possible to calibrate the linear strain gauges by applying the known load to the hook-type digital hanging scale, as shown in Figure 11. The hanging scale was measured against standard weights, and the range of expanded uncertainty plus the measurement error obtained was 0.16 kg for loads between 2 kg and 300 kg, as per its certificate.
Figure 11 – Hook-type digital hanging scale and calibrating label. Loads of 200 kg, 100 kg, and 50 kg were applied to the measuring idler using a calibrated stainless-steel chain and traction on the suspended scale using the adjusting screw. Figure 12 shows the loads applied to the hook scale. For vertical loading, the shaft was positioned using the mounting bubble level. For the horizontal measurement, an auxiliary bubble level was used. For the approximate value of 200 kg, the calibration factors were identified using the auxiliary program developed for the calibrating process.
Figure 12 - Application of horizontal loading on the measuring idler. With the calibration factors identified during the application of known loads to the hook-type digital hanging scale, records were made to verify the differences in measurement, as shown in tables 7 and 8. Table 7 - Vertical loading on the measuring idler. Description Modules tare Load application Relieved load
Standard (kg) Average (kg) Samples Deviation (kg) 0,00 0,257 63 0,257 202,55 202,507 157 -0,043 118,00 117,036 69 -0,964 53,40 53,746 142 0,346 0,00 2,046 100 2,046
Table 8 - Horizontal loading on the measuring idler. Description Modules tare Load application
Relieved load
Standard (kg) Average (kg) Samples Deviation (kg) 0,00 200,50 100,10 50,00 0,00
-0,210 200,432 100,826 50,787 0,021
153 71 52 42 100
-0,210 -0,068 0,726 0,787 0,021
The zero values were calculated for the samples obtained with the unloaded idler, and the deviations from the expected value were −257 g for the vertical measurement and −210 g for the horizontal measurement. The measurements were also averaged for each set of samples corresponding to the target loads of 200 kg, 100 kg, and 50 kg. For the loading of 202.55 kg in the vertical direction, the deviation obtained was 43 g. The load was reduced to 118 kg and 53.40 kg, and the load was finally removed from the idler. The deviation thus obtained was 2046 g under this condition.
For the loading of 200.50 kg in the horizontal direction, the deviation obtained was 68 g, and the load was reduced to 100.10 kg and 50 kg. The deviation obtained was 787 g in this condition. The idler was then removed with a 21-g deviation. The percentage variation obtained in relation to the highest applied loads of 202.55 kg in the vertical direction and 200.50 kg in the horizontal direction was 1.01% for the vertical measurement and 0.39% for the horizontal measurement, respectively. After the calibration process was completed, the measuring idler was installed, and a test was performed to collect the belt-speed data of the measuring idler by operating the empty pipe conveyor at various speeds. The angular speed of reference has been changed to 900 rpm in the equipment frequency inverters. The results obtained in the speed verification test are presented in figure 13. The angular speed recordings were obtained using the OSIsoft PI System ™ platform, which was integrated with the thermal power plant control system. Belt speed records were obtained by the indentation rolling resistance idler.
Figure 13. Belt speed recordings from measurement idler. The correlation coefficient obtained was 0.998927314 for 340 samples. The difference between the value recorded on the measuring idler and the angular speed from the frequency inverters was 0.548% higher during operation at 900 rpm. Table 9 presents the belt-speed measurement data. Table 9 – Belt speed measurement. Correlation
Idler (m/s)
Inverter (m/s)
Samples
Deviation (%)
0,998927314
5,47
5,44
340
0,548
The effect of speed variation on the indentation rolling resistance idler was also evaluated, and the obtained result is presented in figures 14 and 15. For ease of analysis, the load readings are presented in kg.
Figure 14. Loading due to indentation and belt-speed recordings from measuring idler.
Figure 15. Loading due to indentation from measuring idler and main conveyor’s motor current.
The belt used in the pipe conveyor is from the manufacturer Contitech, model: ST1400 1500 mm PIPE DIA / DFPL SLRR 8.0 + 7.0 with 74 cables of 5.4 mm diameter. This belt features a low rolling resistance, good stability, and fast accommodation. The vertical loading was analyzed based on records of coal unloading operations performed using the conveyor system. During the tests, the pipe belt conveyor was operated at a maximum flow of 819.05 tons/h. The flow recording is performed on the integrating scale from the first conveyor upstream of the belt system, and the records were obtained using OSIsoft's PI System ™ platform, which is integrated with the control system of the thermal power plant. Figure 16 presents a comparison of the integrating-scale flow data and the vertical load measurements obtained using the measuring idler. The correlation coefficient obtained was 0.777221023 for 600 samples with 3-s intervals. It is also possible to observe a progressive increase in the measurement differences, which is indicative of drift effects on the strain gauges. The tare of the HX711 modules was obtained when powering up the module while the equipment was in operation. The measured differences were corrected by the smallest value, which was considered as the 0-kg point.
Figure 16. Vertical loading recordings from measuring idler and belt scale flow. For the same data set, evaluations of the effects on the belt-filling degree were performed while measuring the horizontal and rotational loads. The indentation loading was calculated by subtracting the rotational reading value from the horizontal reading value for each sample. Figure 17 presents the results.
Figure 17. Loading recordings obtained from measuring idler. For evaluation purposes, the 600 samples were sorted in ascending order of vertical loading. It is also possible to observe oscillations in the readings due to sensitivity to mechanical disturbances and vibrations during the equipment operation. The vertical-load range in the test was 98.877 kg, while the horizontal-load range was 7.286 kg. The rotational-loading range was 8.054 kg. 5.
Discussion
With respect to the calibration of the shear strain gauges, the measured values by extensometers are influenced by mechanical disturbances in the idler set such as vibrations or loads in orthogonal directions. The torque applied to fix the shaft to the calibration support also causes a measurement disturbance. Owing to the low load, when compared to the diameter of the idler shaft, the presence of noise in the measurements are representative of when the shaft is subjected to operating conditions. However, in terms of the linear-strain-gauge calibration, the measurements presented excellent stability with a low influence of bench disturbances during the data collection. Nevertheless, the application of efforts in the orthogonal plane to the measurement generated some influence on the collected data. The speed measurement obtained by the idler had a strong correlation with and faithfully represents the driving set rotation values. At the end of the test, it was possible to identify a recorded peak speed. This effect was observed during the tests before the complete conveyor's shutdown, when a small reversal movement occurred until the load was balanced on the belt, and the idler rotated in the opposite direction. The indentation values are observed to decrease after the equipment was started. This behavior is justified by the tension that acts on the belt when the starting inertia is overcome, thus relieving the vertical load of the belt due to the tendency of belt-diameter reduction. The belt speed varied over a wide range, but it was possible to observe a slight change in the motor electric current, which indicates that the belt has good accommodation. During the tests, it was possible to observe large oscillations in the horizontal and rotational loading values, and there
was no tendency to increase the indentation as the speed increases, thus reflecting the stability in the electric motor consumption of the belt under no-load operation. There is a strong correlation between the flow and vertical loading data, which demonstrates the accuracy of the measurement performed by the measuring idler. The effects on the measurement due to the flexural strengths of the material and the belt as well as the disturbances caused by vibrations and the temperature must also be considered. As the vertical load on the measuring idler increased, there was a reduction in the horizontal load value and an increase in the rotational load. The indentation rolling resistance decreased as the filling degree increased, which represents behavior convergent to the analytical formulations in the literature. During the tests, it was possible to verify the drift effect in the strain gauge measurements. According to [30], the effect of drift on an extensometer is a time-dependent and usually irreversible change in the performance characteristics of the strain measurement. In addition, there also exists the contribution of temperature variations: the ambient temperature variation affects all transducers, regardless of type, manufacturer or manufacturing process [31]. The resistivity of the conductors used in the Wheatstone bridge was influenced by temperature variations. To reduce this effect, the use of conductors having the largest possible cross-sectional area and shortest possible length and strain gauges of the highest possible strength is recommended [32]. 6.
Conclusion
A measuring idler was developed for horizontal-, vertical-, and rotational-load data acquisition, as well as that of temperature, humidity, and belt speed. A support was designed to calibrate the strain gauge measurements, and the use of ABS parts complemented the assembly to facilitate component clamping and idler speed measurement. The indentation rolling resistance idler was subjected to the various loadings of a long-distance pipe conveyor during coal unloading operations at a thermal power plant. The various aspects considered in the idler mechanical design have met the ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers - Design, selection and standardization [24], thus resulting in the design of a robust and reliable component for industrial operations. Throughout the testing period, no audible noise, overheating, or abnormal vibration was recorded on the component, thus ensuring the necessary conditions for collecting data without an impact on the pipe conveyor operations. The measuring idler shaft was designed for the application of strain gauges and speed sensors, thus enabling the collection of fundamental data for the proposed study, without the requirement of modifications to the pipe conveyor or development of specific collection stations. The development of the calibration support made it possible to identify the extensometer calibration factors in different loading directions, thus providing the user with a method of performing the calibration and test routines on the component. In addition, the printing of ABS parts was important to enable speed data collection via the pulse count sensor positioned on the idler shaft through a custom fastener that was printed using a 3D printer. The strain measurement presented drift disturbances in the strain gauges, but it was possible to analyze the influence of the operational variables on the indentation values. In terms of application modularity, the ABNT NBR 6678: 2018 defines standard dimensions for application including those for the casing diameter and shaft. Similarly, there exist global
recommendations such as CEMA and DIN for this purpose. Therefore, to adapt this design to different idlers, changes in the mechanical components are required for each application. The development of the electronic module embedded in the measuring idler facilitated the recording of the interest data during the conveyor operation without the need for equipment interruptions. Data were properly stored on the memory card and tabulated at predefined intervals with date and time values, thus providing the user with a valuable information source for decision making and analysis regarding the forces acting on the conveyor belt. The analysis of the recorded data indicates that the speed and vertical-loading measurements present a strong correlation and reliability in the measurements. The relationship between the degree of filling and the indentation factor was also confirmed, which decreased as the filling percentage increased. Thus, the indentation measurement method developed has the following technical advantages over traditional methods: the possibility of continuous monitoring of the interaction belt forces with the conveyor idlers, which is considered a key factor influencing the operational reliability of pipe conveyors [23] as the belt transverse stiffness changes over the operating time owing to the fatigue caused in the opening and closing movements. These movements are performed twice with each belt revolution in the conveyor, in the transition regions from the pipe to the open form, and they occur in the loading and unloading equipment zones; In addition, it is possible to evaluate the effect of the conveyor design variables such as tension, speed, and material loading. 7.
Future Works
In addition to the evaluation of the changes in the horizontal loading, it is possible to evaluate the belt speed and any changes resulting from lagging from driving pulleys or even errors in the Variable Speed Drives speed setting. It is also possible to evaluate higher transverse loading points on conveyor curves and to investigate premature idler damage such as bolt shear and bearing failure. The indentation rolling resistance idler enables operational monitoring of a pipe belt conveyor for a wide variety of purposes. In future works, the evaluation of the use of drift-compensated strain gauges and the application of high-precision machining to the idler shaft should be undertaken in order to reduce effects on the measurement. In addition, the use of electronic filters is recommended, to reduce the measurement oscillations, in combination with changes in part geometry, to increase the deformation and reduce the effects due to electrical noise. To facilitate the process of reading the data, it is recommended to increase one of the longitudinal slots in the idler shaft to allow the use of a Micro SD extender, which will allow the removal of the memory card without disassembly of the measuring idler. It is also possible to include an operation indicator LED on the idler to confirm the energization of the electronic module during equipment operation. The measuring idler can also be used to trigger alarms during operation of the conditions of high load, suspected pipe-formation collapse, over speed, or under speed. For this purpose, changes to the source code are required to be made in addition to the use of digital outputs and relays. Loading at various positions of the pipe conveyor can be used for the evaluation of the vertical and horizontal curves and the loading on the side and top idlers. Using six indentation rolling resistance idlers, it is also possible to develop belt-overlap position monitoring and trigger alarms for belt alignment.
The use of autonomous power sources, such as a tachometer generator or rechargeable batteries, is also recommended to power the electronic module, in order to enable the use of remote access from places that are far from the conveyor. It is still possible to use wireless modules for serial communication in the user–equipment interface. 8.
Acknowledgements
The authors sincerely thank UFPA – Universidade Federal do Pará and UEMA – Universidade Estadual do Maranhão, as well as the Companies Hydro Alunorte and Eneva Itaqui. This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors. 9.
References
[1] Z. Yijun, Extended reach: Overland pipe conveyor with low rolling resistance belt, Bulk Solid. Handl. 4 (2013): 16-21. [2] V. Molnár, et al. Monitoring of dependences and ratios of normal contact forces on hexagonal idler housings of the pipe conveyor, Meas. 64 (2015): 168-176. https://doi.org/10.1016/j.measurement.2014.12.055 [3] G. Fedorko, et al., Simulation of interaction of a pipe conveyor belt with moulding rolls. Proc. Eng. 48 (2012): 129-134. https://doi.org/10.1016/j.proeng.2012.09.495 [4] M.E. Zamiralova, and G. Lodewijks, Measurement of a pipe belt conveyor contact forces and cross section deformation by means of the six-point pipe belt stiffness testing device. Meas. 70 (2015): 232-246. https://doi.org/10.1016/j.measurement.2015.03.045 [5] Y.-C. Guo, et al., Optimization and experimental study of transport section lateral pressure of pipe belt conveyor, Adv. Powder Technol. 27.4 (2016): 1318-1324. https://doi.org/10.1016/j.apt.2016.04.026 [6] V. Molnár, et al., Online monitoring of a pipe conveyor. Part I: Measurement and analysis of selected operational parameters. Meas. 94 (2016): 364-371. https://doi.org/10.1016/j.measurement.2016.08.018 [7] M.E. Zamiralova, and G. Lodewijks, Energy consumption of pipe belt conveyors: indentation rolling resistance. FME Trans. 40.4 (2012): 171-176. [8] G. Lodewijks, Determination of rolling resistance of belt conveyors using rubber data: fact or fiction? Bulk Solid. Handl. 23.6 (2003): 384-391. [9] M. Bajda, and R. Krol, Experimental tests of selected constituents of movement resistance of the belt conveyors used in the underground mining. Proc. Earth Planet. Sci. 15 (2015): 702-711. https://doi.org/10.1016/j.proeps.2015.08.098 [10] T.J. Rudolphi, and A.V. Reicks, Viscoelastic indentation and resistance to motion of conveyor belts using a generalized Maxwell model of the backing material. Rubber Chem. Technol. 79.2 (2006): 307-319. https://doi.org/10.5254/1.3547939 [11] L. Gładysiewicz, and M. Konieczna, "Theoretical basis for determining rolling resistance of belt conveyors, Min. Sci. 23 (2016).
[12] L. Gładysiewicz, and M. Konieczna, Analytical method for establishing indentation rolling resistance, E3S Web of Conferences. Vol. 29. EDP Sciences (2018). https://doi.org/10.1051/e3sconf/20182900001 [13] P.W. Robinson, and C.A. Wheeler, The indentation rolling resistance of spherically profiled idler rolls, Int. J. Mech. Sci. 106 (2016): 363-371. https://doi.org/10.1016/j.ijmecsci.2015.12.001 [14] J.I. O’Shea, and C.A. Wheeler, Dielectric relaxation studies of conveyor belt compounds to determine indentation rolling resistance, Int. J. Mech. Mater. Des. 13.4 (2017): 553-567. [15] Y. Lu, F.-Y. Lin, and Y.-C. Wang, Investigation on influence of speed on rolling resistance of belt conveyor based on viscoelastic properties, J. Theoret. Appl. Mech. 45.3 (2015): 53-68. https://doi.org/10.1515/jtam-2015-0017 [16] C. Wheeler, and P. Munzenberger, Indentation rolling resistance measurement. Retrieved May 4 (2016). [17] M.A. Lodder, A survey of indentation rolling resistance models for belt conveyors-Een overzicht van vervormingsrolweerstand modellen in riemtransport systemin, (2017). [18] D. Woźniak, L. Gładysiewicz, and M. Konieczna, Experimental tests of the impact of selected parameters on the indentation rolling resistances. E3S Web of Conferences. Vol. 29. EDP Sciences (2018). https://doi.org/10.1051/e3sconf/20182900002 [19] P. Munzenberger, and C. Wheeler, Laboratory measurement of the indentation rolling resistance of conveyor belts, Meas. 94 (2016): 909-918. https://doi.org/10.1016/j.measurement.2016.08.030 [20] DIN EN 16974:2016 Conveyor belts - Indentation rolling resistance related to belt width Requirements, testing; German version EN 16974 (2016). [21] AS 1334.13:2017 Methods of testing conveyor and elevator belting Determination of indentation rolling resistance of conveyor belting; Standards Australia (2017). [22] A.V. Reicks, T.J. Rudolphi, and C.A. Wheeler, Science-A Comparison of Calculated and Measured Indentation Losses in Rubber Belt Covers, Bulk Solid. Handl. 32.3 (2012): 52. [23] V. Molnár, et al., Online monitoring of pipe conveyors part II: Evaluation of selected operational parameters for the design of expert system, Meas. 104 (2017): 1-11. https://doi.org/10.1016/j.measurement.2017.03.011 [24] ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers Design, selection and standardization; Standards Brazil (2018). [25] Y. Lu, and F. Lin, A study of indentation rolling resistance to motion of conveyor belts using a generalized Maxwell model of the backing material, Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol. 230.8 (2016): 1006-1018. https://doi.org/10.1177/1350650115622778 [26] S. Drenkelford, Energy-saving potential of Aramid-based conveyor belts, (2015). [27] S. Zamorano, Reducing energy consumption on overland conveyors, Eng. Mining J. 210.5 (2009): 58. [28] C. Wheller et al., Energy Efficient Belt Conveyor Design. TUNRA Bulk Solids Research Associates: The University of Newcastle, Australia. 27p. (2018).
[29] Belt Analyst. Pipe Conveyor Power Calculations. http://overlandconveyor.com/help/nethelp/index.html?pipe-indeterminateanalysis.html (2017), (accessed 24 May 2018). [30] R.L. Hannah, and S.E. Reed, eds. Strain Gage Users' handbook. Springer Science & Business Media (1992). [31] K. Ekola, M. Breen, Tension transducer strain gages: which technology is better? The foil vs. semiconductor (silicon) strain gage debate, Tech. Bull. (2009). [32] R. Klosse, H. Söker, and T. Kramkowski, Temperature induced drift in mechanical load measurements on wind turbines. DEWI Magazin Nr. 30, February. (2007).
Title page for manuscript
December 20, 2019 Editorial Department of the Journal of the International Measurement Confederation Mr. P. Sivakumar Dear Mr. P. Sivakumar, This is the title page for manuscript MEASUR 107413 TITLE OF THE SUBMITTED MANUSCRIPT:
Development of idler for measuring indentation rolling resistance in pipe conveyor belts.
LIST OF ALL AUTHORS’ NAMES AND AFFILIATIONS: M.Eng. Leonardo dos Santos e Santos, Postgraduate Program in Process Engineering (PPGEP) at the Federal University of Pará (UFPA) orcid: 0000 0002 2038 1184 [email protected] +55 98 9 9161 5511 (personal mobile)
São Luís, Maranhão, Brazil
M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho, Mechanical Engineering Department at the State University of Maranhão (UEMA) orcid: 0000 0002 6066 1041 [email protected]
D.Sc. Emanuel Negrão Macêdo, Postgraduate Program in Process Engineering (PPGEP) at the Federal University of Pará (UFPA) orcid: 0000 0002 4652 8316 [email protected]
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Highlights
Development of a low-cost method for measuring pipe-belt-conveyor indentation Designing, fabricating, and assembling a load idler in accordance with ABNT NBR 6678: 2018 Electronic module embedded in the measuring idler Effect of operating conditions on indentation value.
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Author’s name M.Eng. Leonardo dos Santos e Santos M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho D.Sc. Emanuel Negrão Macêdo
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S0263-2241(19)31280-1 https://doi.org/10.1016/j.measurement.2019.107413 MEASUR 107413
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Please cite this article as: L. dos Santos e Santos, P. Roberto Campos Flexa Ribeiro Filho, E. Negrão Macêdo, Development of idler for measuring indentation rolling resistance in pipe conveyor belts, Measurement (2019), doi: https://doi.org/10.1016/j.measurement.2019.107413
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Title Development of idler for measuring indentation rolling resistance in pipe conveyor belts
Authors M.Eng. Leonardo dos Santos e Santos, orcid: 0000 0002 2038 1184 M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho, orcid: 0000 0002 6066 1041 D.Sc. Emanuel Negrão Macêdo, orcid: 0000 0002 4652 8316
Abstract The major contribution to energy consumption in a pipe conveyor is from indentation rolling resistance, which is also called viscoelastic resistance. Reproducing the effects of actual operating conditions is a challenge for direct measurements, as samples from the original belt are currently used for small-scale laboratory testing. This paper presents a low-cost measuring idler developed for indentation data acquisition from pipe conveyors under different conditions. Using a calibration support and an electronic module for data storage, it was possible to analyze the belt speed, temperature, humidity, and vertical, horizontal, and rotational loads. The correlation coefficients obtained for the belt speed and vertical loading measurements were, respectively, as follows: 0.998927314 for 340 samples, and 0.777221023 for 600 samples. The indentation rolling resistance values decreases as the belt filling degree increased, and the production cost was feasible for industrial production. Keywords 1.Indentation 2. Measuring idler 3. Pipe conveyor. 1.
Introduction
Pipe conveyors are an advantageous alternative to the conventional belt conveyor as they circumvent the technical limitations of the latter [1,2,3,4,5,6,7]. A pipe conveyor comprises a conveyor belt enclosed by hexagonal panels, and a completely closed tube is thus obtained owing to the overlapping of the belt edges. In addition, to preventing interactions between the handled material and the environment, pipe conveyors have great flexibility in geometry in the case of vertical and horizontal curvatures [7]. As compared to a conventional belt conveyor, a tubular one consumes, on average, twice the energy for the same distance [1]. The belt rolling resistance distributed at each idler along the conveyor is the sum of the forces due to (i) the rotational inertia of the idlers, (ii) material flexural deformation, (iii) belt flexural deformation, and (iv) idlers indentation in the belt. The indentation rolling resistance formed in a pipe belt conveyor is larger than that in a conventional one [7]. Furthermore, in the case of a conventional belt, this force corresponds to between 50 and 60% of the total equipment energy consumption [7,8,9,10,11,12,13]. In addition, the belt costs can comprise up to 70% of the equipment costs [8]. Rubber composite materials are viscoelastic and, therefore, exhibit variations in their properties between those of elastic solids and viscous liquids depending on the experimental conditions [14]. As the belt moves over a conveyor idler, the pressure exerted at the initial contact area increases via compression, and the pressure under the final contact area is reduced owing to material hysteresis. The rubber back cover expands more slowly than it is compressed, thus
resulting in the formation of an asymmetrical stress distribution. This variation in tension generates a motion reaction force called indentation rolling resistance or viscoelastic resistance [14,15,16,7]. There exist different methods for establishing indentation values. Some of them are as follows: (i) the analytical methods of Lanchmann, 1954; May et al., 1959; Hunter, 1961; Morland, 1962; Spaans, 1978; Jonkers, 1980; Johnson, 1985; Lodewijks, 1995; Qiu, 2006; Rudolphi, 2005; Lu and Lin, 2016 [17]; (ii) Wheeler's finite element method (FEM) and Qui's boundary element method (BEM), which is an offshoot of the analytical method; and (iii) direct measurement methods such as the inclined plane experiment [9], hydraulic actuator [18], and the Conveyor Equipment Manufacturers Association (CEMA) two-pulley test machine [9,19], which the DIN EN 16974: 2016 and AS 1334.13: 2017 standards apply [20,21]. Direct indentation measurement presents practical challenges in separating the contribution of the belt back cover from other losses as well as in evaluating the effect of the conveyor design variables such as tension, speed, and material loading. Reproducing the effects of actual operating conditions also presents a challenge in obtaining direct measurements, as samples from the original belt are used for small-scale laboratory testing [22,20,21]. The continuous monitoring of the forces of the belt interaction with the conveyor idlers is a key factor affecting the operational reliability of pipe conveyors [23] as the transverse stiffness of the belt changes with the operating time as a function of the fatigue caused in the belt opening and closing movements. These movements are performed twice in each belt revolution, i.e., in the transition regions from pipe shape to open form. Given the importance of tubular conveyors in industrial bulk handling processes and the impact of indentation on the design of this type of equipment, it is necessary to develop devices for measuring the opposing force to the belt rolling, which would benefit plant operation, designing of new equipment, and development of belt compounds. In the case of existing equipment, it is possible to establish end-of-life predictors as well as safeguards that minimize operational risks. In the case of new projects, it is possible to apply finer mathematical formulations and create standards for pipe conveyor designs. This paper presents the development of a low-cost method for measuring pipe-belt-conveyor indentation data by (i) designing, fabricating, and assembling a load idler having an operational capacity in accordance with ABNT NBR 6678: 2018 – Continuous conveyors, belt conveyors Idlers - Design, selection and standardization [24]; (ii) dimensioning, installing, and calibrating strain gauges and speed sensors that are appropriately arranged on the measuring idler shaft for the acquisition of velocity and strain data in the vertical and horizontal planes; (iii) parameterizing and programming the prototyping platform for processing deformation and velocity data as well as transferring data to the computer for storage, analysis, and reporting. 2.
Material and methods
For the development of the indentation measurement methodology for a tubular belt conveyor, a commissioned and operational equipment was selected for determining the idler to be used, as shown in figure 1. The basic design data of the selected conveyor is presented in table 1.
Figure 1 – Selected pipe conveyor and hexagonal panels. Table 1 – Design data of selected tubular conveyor. Conveyor Technical Data Design capacity Carried material Belt speed Pipe diameter Drive power Developed Length Horizontal curves Idlers (hexagonal panels)
t/h m/s mm kW m und und
1,000 bituminous coal 5.1 375 3 x 550 4,283 14 23,349
The basic data of a typical load idler of the selected pipe conveyor is presented in Table 2. Table 2 – Idler technical data. Idler Technical Data Idler diameter Shaft diameter Idler width Maximum eccentricity Material Fastening type Bearing type 1.
mm mm mm mm -
165.1 30 345 0.6 Carbon steel Screw fastening Ball bearing
Defining Measuring Idler Characteristics
The first step in defining the construction characteristics of the measuring idler was the selection of interest parameters in the indentation measurement. Table 3 presents the selected parameters and their descriptions. Table 3 – Parameters selected for measuring idler. Parameter
Description
Horizontal force Vertical force Torque Speed
Indentation resistance measurement Evaluation of effect on indentation Rotational resistance measurement Evaluation of effect on indentation
Temperature Humidity Date and time Memory
Evaluation of effect on indentation Evaluation of effect on indentation Database Database
The geometry of the measuring idler shaft was defined in order to allow transducers and electronics to acquire these parameters while being embedded in the idler. Thus, it was necessary to anticipate the requirement for the inclusion of a prototyping platform in the idler and consider openings in the shaft, both for the connection of electronic cabling and the renewal of air inside the idler, as it is temperature and humidity data collection required.
Figure 2 –Indentation rolling resistance idler. Four longitudinal slots were thus included in the design. These were designed to mitigate the influences of stresses on orthogonal planes. In the shaft central part, four larger openings were considered to allow the application of linear extensometers. At the shaft ends, two opposite openings were arranged for positioning shear strain gauges in order to measure the rotational forces due to the bearings.
Figure 3 – Exploded view of indentation measuring idler. 2.
Detailing of mechanical parts
With the conceptual data defined, the mechanical assembly details were then defined. The material selected for the shaft was AISI 304 stainless steel. The material selected for the bearings and idler housing was AISI 1020 carbon steel. The fasteners for the electronic circuit, pulse-count sensor fastener, and toothed crown were fabricated from ABS (acrylonitrile butadiene styrene) as it is a lightweight, inexpensive material that can be used in 3D printers. Deep-groove ball bearings 6306 were selected, to obtain the same characteristics as those of the typical pipe conveyor idler, while using 2RS seal to facilitate mounting without the requirement for additional sealing. The retaining rings to hold the bearings in the mounting positions have been specified as SAE 1070 DIN 471 carbon steel. Each bearing is secured using 10 AISI-304-stainlesssteel Allen DIN 912 head screws.
Figure 4 – Indentation rolling resistance idler assembly.
3.
Details of electronics
The electronic components required to collect each of the interest variables were specified. The prototyping platform was first selected: the low-cost, open-source Arduino Mega. For the horizontal, vertical, and rotational force readings, four Avia Semiconductor model HX711 plates were selected for reading strain gauges. No additional filters were used for conditioning the extensometer signals. The pulse-count sensor selected was YwRobot's IR Switch. To acquire temperature and humidity data, Aosong module AM2302 was selected. For the timestamp, the Maxim Integrated DS3231 Real Time Clock module was selected. For storing the collected data, the Catalex Micro SD Adapter module with 5-V direct interface and support for memory cards was selected. Figure 5 presents an overview of the electronic components.
Figure 5 – Electronics for measuring idler. The other components selected were eight linear precision strain gauges for measuring the horizontal and vertical strains, and four half-bridge shear strain gauges for measuring the rotational strain (350±0.1 Ohms). The complete Wheatstone bridge configuration was used for the strain measurements.
Figure 6 – Electronics used in measurement idler shaft. 4.
Details of calibration support
A calibration support was developed for an application of known loading and in the selected planes. The support comprised a round bar of AISI-304 stainless steel. The following materials have been specified for the other accessories: one 300-kg digital hook-type hanging scale MNCSM from Mini Crane; and one AISI-316 stainless-steel swivel shackle, which has been modified to include a DIN 933 hex head screw to pull the balance and subject the idler to known loads.
Figure 7 – Calibrating of indentation rolling resistance idler. 5.
Checking of loaded components
Verification was performed via FEM using computational modeling as well as a buckling analysis for the calibration support. The measuring idler was also evaluated in relation to the different aspects considered in ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers - Design [24]. The measuring idler was approved in terms of this various aspects, and it was thus considered to be suitable for use in the selected pipe conveyor, which made the methodology feasible. Table 4 presents the evaluation of the measuring idler against the standard criteria. Table 4 – Measurement idler analysis with respect to considerations of ABNT 6678:2018 [24].
Item 8.6.1 8.6.2 8.7.2 8.9.3 9.3.5 9.3.6 9.6.1
Description
Criteria
Reference Value
Measurement Idler
50
49.8
4,599 26,700 600 13.4 4.25 0.6
4,599 29,600 590 11.4 4.7625 0.6
Distance from bearing center to idler mm (maximum) attachment point Allowable load on idlers Bearing dynamic load (6306) Idler rotating speed Idler mass Minimum wall thickness Eccentricity tolerance
N (minimum) N (minimum) rpm (maximum) kg (maximum) mm(minimum) mm (maximum)
Source: Adapted from [24].
Figure 8 – Collecting conveyor data using indentation rolling resistance idler. 3.
Theory and Calculations
In scientific production, an analytical formula was developed [25] based on a simplification of Rudolphi's formulations [10] and the application of Jonkers' formulations [26] as a reference for this purpose, as shown in Eq. (1): 2𝐸0 𝑉𝑏2𝑃 1 3 3 𝐹ℎ = (𝜏𝜆) 2 ― 𝜏²𝜆² 4 3 𝑅2 𝑃𝑅ℎ 𝑅 𝑉 𝑏𝑃
(
) ( )
1 3
(1)
𝜆=
𝐸1
(2)
𝐸0
The constants related to the viscoelastic material parameters are separated, and the analytical formula is presented for the indentation force [25]:
𝐹ℎ = 𝐴
𝑉 𝑏𝑃 𝑅2
―𝐵
𝑉𝑏2𝑃 𝑅2
1 3
( ) 1 𝑃𝑅ℎ
(3)
Being: 𝐹ℎ = 𝐼𝑛𝑑𝑒𝑛𝑡𝑎𝑡𝑖𝑜𝑛 𝑟𝑜𝑙𝑙𝑖𝑛𝑔 𝑟𝑒𝑠𝑖𝑠𝑛𝑡𝑎𝑐𝑒 𝑖𝑛 𝑁/𝑚; 𝑃 = 𝑉𝑒𝑟𝑡𝑖𝑐𝑎𝑙 𝑙𝑜𝑎𝑑 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑏𝑒𝑙𝑡 𝑎𝑛𝑑 𝑖𝑑𝑙𝑒𝑟 𝑖𝑛 𝑁/𝑚; ℎ = 𝐵𝑒𝑙𝑡 𝑏𝑎𝑐𝑘 𝑐𝑜𝑣𝑒𝑟 𝑡ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 𝑖𝑛 𝑚; 𝑉𝑏 = 𝐵𝑒𝑙𝑡 𝑠𝑝𝑒𝑒𝑑 𝑖𝑛 𝑚/𝑠; 𝑅 = 𝐼𝑑𝑙𝑒𝑟 𝑟𝑎𝑑𝑖𝑢𝑠 𝑖𝑛 𝑚; 𝐴 𝑎𝑛𝑑 𝐵 = 𝑀𝑎𝑡𝑒𝑟𝑖𝑎𝑙 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡𝑠 𝑑𝑒𝑝𝑒𝑛𝑑𝑖𝑛𝑔 𝑜𝑛 𝜏, 𝐸0 𝑎𝑛𝑑 𝐸1; 𝐸0 = 𝐸𝑞𝑢𝑖𝑙𝑖𝑏𝑟𝑖𝑢𝑚 𝑚𝑜𝑑𝑢𝑙𝑢𝑠 𝑖𝑛 𝑃𝑎; 𝐸1 = 𝑀𝑜𝑑𝑒𝑙′𝑠 𝑒𝑙𝑎𝑠𝑡𝑖𝑐 𝑒𝑙𝑒𝑚𝑒𝑛𝑡 𝑖𝑛 𝑃𝑎; 𝜏 = 𝑅𝑒𝑙𝑎𝑥𝑎𝑡𝑖𝑜𝑛 𝑡𝑖𝑚𝑒 𝑖𝑛 𝑠; This analytical formula reflects the influence of common working conditions such as vertical loading, belt speed, idler diameter, and belt back cover thickness [25]. According to [10], the compounds used in the belt back cover are highly dependent on the temperature and loading frequency. [27] presented a reduction in the indentation factor with increasing temperature for a variety of return covers, including low-rolling-resistance belts. The belt carcass also has a significant influence on the indentation rolling resistance, as experiments show that textile-reinforced belts have higher indentation values than steel-cordreinforced belts. In addition, belts having smaller diameters on wire ropes have lower indentation values [28]. For the calculation of the indentation factor, considering the contact of the pipe belt with the surface of the conveyor idler, Eq. (4) is used [7]:
( ) 6
𝑓𝑖𝑛𝑑 =
∑𝐹
𝑟𝑛
𝑛=1
1
(𝑚𝑚′ +
𝑚𝑏′) 𝑔 𝑙′
where: 𝑓𝑖𝑛𝑑 = 𝐼𝑛𝑑𝑒𝑛𝑡𝑎𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 𝑓𝑜𝑟 𝑝𝑖𝑝𝑒 𝑐𝑜𝑛𝑣𝑒𝑦𝑜𝑟, 𝑤ℎ𝑖𝑐ℎ 𝑖𝑠 𝑑𝑖𝑚𝑒𝑛𝑠𝑖𝑜𝑛𝑙𝑒𝑠𝑠;
(4)
𝑛 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑖𝑑𝑙𝑒𝑟𝑠 𝑓𝑜𝑟 𝑎 𝑔𝑖𝑣𝑒𝑛 𝑝𝑎𝑛𝑒𝑙; 𝑚𝑚′ = 𝐿𝑖𝑛𝑒𝑎𝑟 𝑚𝑎𝑠𝑠 𝑐𝑎𝑟𝑟𝑖𝑒𝑑 𝑖𝑛 𝑘𝑔/𝑚; 𝑚′𝑏 = 𝐵𝑒𝑙 𝑙𝑖𝑛𝑒𝑎𝑟 𝑚𝑎𝑠𝑠 𝑖𝑛 𝑘𝑔/𝑚; 𝑔 = 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑖𝑜𝑛 𝑖𝑛 𝑚/𝑠²; 𝑙′ = 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑝𝑎𝑛𝑒𝑙𝑠 𝑖𝑛 𝑚; From Eq. (4), it can be concluded that the increase in the pipe conveyor filling degree causes a reduction in the indentation factor [7]. The stiffness of the belt remains the same; however, as the load increases, the overall friction factor decreases as a function of the carried-material flexural strength. According to [29], the belt transverse stiffness is an important variable in the design of belts in pipe conveyors: if the belt diameter is reduced or if the belt does not touch all the idlers on the panel, it may result in a twist effect or overlap rotation. These situations are undesirable and can result in material leakage, premature damage to the overlap outer edge, collapse of the tubular formation, and difficulty in opening in the discharge drum: these situations can cause major problems for the user, with impacts on availability and operational safety. In addition, according to [29], the transverse stiffness of the belt decreases as the number of cycles increases as a function of the repetitive bending movement; thus, the indentation force on the idlers is reduced. By analyzing Eq. (4), it is also possible to evaluate the effect of the distance between the conveyor panels on the indentation factor. Increasing the spacing between panels results in a reduction in the indentation rolling resistance. According to [28], a reduction in the number of times the belt is flexed between the panels along the conveyor reduces the belt and material flexural strengths. 1.
Influence of variables on indentation values
The indentation value of a given belt conveyor is influenced by several factors, including the operating conditions and material characteristics employed—particularly in the belt and idler design. Table 5 presents the effects of the main variables under study. When not indicated, it can be considered that there is an effect on both the conventional and pipe conveyors. Table 5 – Effect of operating conditions on indentation value. Variable Belt speed Vertical load (conventional) Back cover thickness Idler radius Temperature Panel spacing Transverse stiffness (tubular) Number of cycles (tubular) Filling degree (tubular) Linear belt mass (tubular)
Variable behavior
Effect on indentation
↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑ ↑
↑ ↑ ↓ ↓ ↓ ↓ ↑ ↓ ↓ ↓
Source: Adapted from [29,25,7,27,28] 4.
Results
In order to calibrate the shear strain gauges, the measuring idler shaft was mounted on the calibration support, and a special tool was developed to apply known and certified masses, as illustrated in Figure 9.
Figure 9 - Support for applying rotational loads. Known masses of 200 g, 500 g, 1000 g, and 2000 g were applied to the special tool attached to the idler shaft, and the calibration factors were obtained through an auxiliary program developed for the calibration process.
Figure 10 - Application of standard weights of 1000 g and 2000 g, respectively. With the calibration factors identified during application of the standard masses of 2000 g, records were made to verify the differences in measurement, as shown in Table 6. Table 6 - Rotational loading on measuring idler shaft. Description
Standard (g)
Right (g)
Left (g)
Samples
Deviation (g)
Modules tare Modules tare
0 0 2,000
0.113 2,119.328
0.323 -
379 379 323
0.113 0.323 119.328
Load application
Load application
2,000
-
2,182.464
323
182.464
Zero values were averaged for 379 samples, and the difference from the expected value was 0.113 g for the right-hand-side measurements and 0.323 g for the left-hand-side measurements. A standard weight of 2000 g was applied on each support of the measuring idler shaft, and 323 samples were obtained; the difference from the expected value was 119.328 g for the right-side measurement and 182.464 g for the measurement left side. The percentage change obtained in relation to the largest applied load of 2000 g was 5.96% for the right-hand-side measurement and 9.12% for the left-hand-side measurement. This equals 7.54% for the total load of 4000 g. After mounting the measuring idler on the calibrating support, it was possible to calibrate the linear strain gauges by applying the known load to the hook-type digital hanging scale, as shown in Figure 11. The hanging scale was measured against standard weights, and the range of expanded uncertainty plus the measurement error obtained was 0.16 kg for loads between 2 kg and 300 kg, as per its certificate.
Figure 11 – Hook-type digital hanging scale and calibrating label. Loads of 200 kg, 100 kg, and 50 kg were applied to the measuring idler using a calibrated stainless-steel chain and traction on the suspended scale using the adjusting screw. Figure 12 shows the loads applied to the hook scale. For vertical loading, the shaft was positioned using the mounting bubble level. For the horizontal measurement, an auxiliary bubble level was used. For the approximate value of 200 kg, the calibration factors were identified using the auxiliary program developed for the calibrating process.
Figure 12 - Application of horizontal loading on the measuring idler. With the calibration factors identified during the application of known loads to the hook-type digital hanging scale, records were made to verify the differences in measurement, as shown in tables 7 and 8. Table 7 - Vertical loading on the measuring idler. Description Modules tare Load application Relieved load
Standard (kg) Average (kg) Samples Deviation (kg) 0,00 0,257 63 0,257 202,55 202,507 157 -0,043 118,00 117,036 69 -0,964 53,40 53,746 142 0,346 0,00 2,046 100 2,046
Table 8 - Horizontal loading on the measuring idler. Description Modules tare Load application
Relieved load
Standard (kg) Average (kg) Samples Deviation (kg) 0,00 200,50 100,10 50,00 0,00
-0,210 200,432 100,826 50,787 0,021
153 71 52 42 100
-0,210 -0,068 0,726 0,787 0,021
The zero values were calculated for the samples obtained with the unloaded idler, and the deviations from the expected value were −257 g for the vertical measurement and −210 g for the horizontal measurement. The measurements were also averaged for each set of samples corresponding to the target loads of 200 kg, 100 kg, and 50 kg. For the loading of 202.55 kg in the vertical direction, the deviation obtained was 43 g. The load was reduced to 118 kg and 53.40 kg, and the load was finally removed from the idler. The deviation thus obtained was 2046 g under this condition.
For the loading of 200.50 kg in the horizontal direction, the deviation obtained was 68 g, and the load was reduced to 100.10 kg and 50 kg. The deviation obtained was 787 g in this condition. The idler was then removed with a 21-g deviation. The percentage variation obtained in relation to the highest applied loads of 202.55 kg in the vertical direction and 200.50 kg in the horizontal direction was 1.01% for the vertical measurement and 0.39% for the horizontal measurement, respectively. After the calibration process was completed, the measuring idler was installed, and a test was performed to collect the belt-speed data of the measuring idler by operating the empty pipe conveyor at various speeds. The angular speed of reference has been changed to 900 rpm in the equipment frequency inverters. The results obtained in the speed verification test are presented in figure 13. The angular speed recordings were obtained using the OSIsoft PI System ™ platform, which was integrated with the thermal power plant control system. Belt speed records were obtained by the indentation rolling resistance idler.
Figure 13. Belt speed recordings from measurement idler. The correlation coefficient obtained was 0.998927314 for 340 samples. The difference between the value recorded on the measuring idler and the angular speed from the frequency inverters was 0.548% higher during operation at 900 rpm. Table 9 presents the belt-speed measurement data. Table 9 – Belt speed measurement. Correlation
Idler (m/s)
Inverter (m/s)
Samples
Deviation (%)
0,998927314
5,47
5,44
340
0,548
The effect of speed variation on the indentation rolling resistance idler was also evaluated, and the obtained result is presented in figures 14 and 15. For ease of analysis, the load readings are presented in kg.
Figure 14. Loading due to indentation and belt-speed recordings from measuring idler.
Figure 15. Loading due to indentation from measuring idler and main conveyor’s motor current.
The belt used in the pipe conveyor is from the manufacturer Contitech, model: ST1400 1500 mm PIPE DIA / DFPL SLRR 8.0 + 7.0 with 74 cables of 5.4 mm diameter. This belt features a low rolling resistance, good stability, and fast accommodation. The vertical loading was analyzed based on records of coal unloading operations performed using the conveyor system. During the tests, the pipe belt conveyor was operated at a maximum flow of 819.05 tons/h. The flow recording is performed on the integrating scale from the first conveyor upstream of the belt system, and the records were obtained using OSIsoft's PI System ™ platform, which is integrated with the control system of the thermal power plant. Figure 16 presents a comparison of the integrating-scale flow data and the vertical load measurements obtained using the measuring idler. The correlation coefficient obtained was 0.777221023 for 600 samples with 3-s intervals. It is also possible to observe a progressive increase in the measurement differences, which is indicative of drift effects on the strain gauges. The tare of the HX711 modules was obtained when powering up the module while the equipment was in operation. The measured differences were corrected by the smallest value, which was considered as the 0-kg point.
Figure 16. Vertical loading recordings from measuring idler and belt scale flow. For the same data set, evaluations of the effects on the belt-filling degree were performed while measuring the horizontal and rotational loads. The indentation loading was calculated by subtracting the rotational reading value from the horizontal reading value for each sample. Figure 17 presents the results.
Figure 17. Loading recordings obtained from measuring idler. For evaluation purposes, the 600 samples were sorted in ascending order of vertical loading. It is also possible to observe oscillations in the readings due to sensitivity to mechanical disturbances and vibrations during the equipment operation. The vertical-load range in the test was 98.877 kg, while the horizontal-load range was 7.286 kg. The rotational-loading range was 8.054 kg. 5.
Discussion
With respect to the calibration of the shear strain gauges, the measured values by extensometers are influenced by mechanical disturbances in the idler set such as vibrations or loads in orthogonal directions. The torque applied to fix the shaft to the calibration support also causes a measurement disturbance. Owing to the low load, when compared to the diameter of the idler shaft, the presence of noise in the measurements are representative of when the shaft is subjected to operating conditions. However, in terms of the linear-strain-gauge calibration, the measurements presented excellent stability with a low influence of bench disturbances during the data collection. Nevertheless, the application of efforts in the orthogonal plane to the measurement generated some influence on the collected data. The speed measurement obtained by the idler had a strong correlation with and faithfully represents the driving set rotation values. At the end of the test, it was possible to identify a recorded peak speed. This effect was observed during the tests before the complete conveyor's shutdown, when a small reversal movement occurred until the load was balanced on the belt, and the idler rotated in the opposite direction. The indentation values are observed to decrease after the equipment was started. This behavior is justified by the tension that acts on the belt when the starting inertia is overcome, thus relieving the vertical load of the belt due to the tendency of belt-diameter reduction. The belt speed varied over a wide range, but it was possible to observe a slight change in the motor electric current, which indicates that the belt has good accommodation. During the tests, it was possible to observe large oscillations in the horizontal and rotational loading values, and there
was no tendency to increase the indentation as the speed increases, thus reflecting the stability in the electric motor consumption of the belt under no-load operation. There is a strong correlation between the flow and vertical loading data, which demonstrates the accuracy of the measurement performed by the measuring idler. The effects on the measurement due to the flexural strengths of the material and the belt as well as the disturbances caused by vibrations and the temperature must also be considered. As the vertical load on the measuring idler increased, there was a reduction in the horizontal load value and an increase in the rotational load. The indentation rolling resistance decreased as the filling degree increased, which represents behavior convergent to the analytical formulations in the literature. During the tests, it was possible to verify the drift effect in the strain gauge measurements. According to [30], the effect of drift on an extensometer is a time-dependent and usually irreversible change in the performance characteristics of the strain measurement. In addition, there also exists the contribution of temperature variations: the ambient temperature variation affects all transducers, regardless of type, manufacturer or manufacturing process [31]. The resistivity of the conductors used in the Wheatstone bridge was influenced by temperature variations. To reduce this effect, the use of conductors having the largest possible cross-sectional area and shortest possible length and strain gauges of the highest possible strength is recommended [32]. 6.
Conclusion
A measuring idler was developed for horizontal-, vertical-, and rotational-load data acquisition, as well as that of temperature, humidity, and belt speed. A support was designed to calibrate the strain gauge measurements, and the use of ABS parts complemented the assembly to facilitate component clamping and idler speed measurement. The indentation rolling resistance idler was subjected to the various loadings of a long-distance pipe conveyor during coal unloading operations at a thermal power plant. The various aspects considered in the idler mechanical design have met the ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers - Design, selection and standardization [24], thus resulting in the design of a robust and reliable component for industrial operations. Throughout the testing period, no audible noise, overheating, or abnormal vibration was recorded on the component, thus ensuring the necessary conditions for collecting data without an impact on the pipe conveyor operations. The measuring idler shaft was designed for the application of strain gauges and speed sensors, thus enabling the collection of fundamental data for the proposed study, without the requirement of modifications to the pipe conveyor or development of specific collection stations. The development of the calibration support made it possible to identify the extensometer calibration factors in different loading directions, thus providing the user with a method of performing the calibration and test routines on the component. In addition, the printing of ABS parts was important to enable speed data collection via the pulse count sensor positioned on the idler shaft through a custom fastener that was printed using a 3D printer. The strain measurement presented drift disturbances in the strain gauges, but it was possible to analyze the influence of the operational variables on the indentation values. In terms of application modularity, the ABNT NBR 6678: 2018 defines standard dimensions for application including those for the casing diameter and shaft. Similarly, there exist global
recommendations such as CEMA and DIN for this purpose. Therefore, to adapt this design to different idlers, changes in the mechanical components are required for each application. The development of the electronic module embedded in the measuring idler facilitated the recording of the interest data during the conveyor operation without the need for equipment interruptions. Data were properly stored on the memory card and tabulated at predefined intervals with date and time values, thus providing the user with a valuable information source for decision making and analysis regarding the forces acting on the conveyor belt. The analysis of the recorded data indicates that the speed and vertical-loading measurements present a strong correlation and reliability in the measurements. The relationship between the degree of filling and the indentation factor was also confirmed, which decreased as the filling percentage increased. Thus, the indentation measurement method developed has the following technical advantages over traditional methods: the possibility of continuous monitoring of the interaction belt forces with the conveyor idlers, which is considered a key factor influencing the operational reliability of pipe conveyors [23] as the belt transverse stiffness changes over the operating time owing to the fatigue caused in the opening and closing movements. These movements are performed twice with each belt revolution in the conveyor, in the transition regions from the pipe to the open form, and they occur in the loading and unloading equipment zones; In addition, it is possible to evaluate the effect of the conveyor design variables such as tension, speed, and material loading. 7.
Future Works
In addition to the evaluation of the changes in the horizontal loading, it is possible to evaluate the belt speed and any changes resulting from lagging from driving pulleys or even errors in the Variable Speed Drives speed setting. It is also possible to evaluate higher transverse loading points on conveyor curves and to investigate premature idler damage such as bolt shear and bearing failure. The indentation rolling resistance idler enables operational monitoring of a pipe belt conveyor for a wide variety of purposes. In future works, the evaluation of the use of drift-compensated strain gauges and the application of high-precision machining to the idler shaft should be undertaken in order to reduce effects on the measurement. In addition, the use of electronic filters is recommended, to reduce the measurement oscillations, in combination with changes in part geometry, to increase the deformation and reduce the effects due to electrical noise. To facilitate the process of reading the data, it is recommended to increase one of the longitudinal slots in the idler shaft to allow the use of a Micro SD extender, which will allow the removal of the memory card without disassembly of the measuring idler. It is also possible to include an operation indicator LED on the idler to confirm the energization of the electronic module during equipment operation. The measuring idler can also be used to trigger alarms during operation of the conditions of high load, suspected pipe-formation collapse, over speed, or under speed. For this purpose, changes to the source code are required to be made in addition to the use of digital outputs and relays. Loading at various positions of the pipe conveyor can be used for the evaluation of the vertical and horizontal curves and the loading on the side and top idlers. Using six indentation rolling resistance idlers, it is also possible to develop belt-overlap position monitoring and trigger alarms for belt alignment.
The use of autonomous power sources, such as a tachometer generator or rechargeable batteries, is also recommended to power the electronic module, in order to enable the use of remote access from places that are far from the conveyor. It is still possible to use wireless modules for serial communication in the user–equipment interface. 8.
Acknowledgements
The authors sincerely thank UFPA – Universidade Federal do Pará and UEMA – Universidade Estadual do Maranhão, as well as the Companies Hydro Alunorte and Eneva Itaqui. This research did not receive any specific grant from funding agencies in the public, commercial, or not-forprofit sectors. 9.
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[12] L. Gładysiewicz, and M. Konieczna, Analytical method for establishing indentation rolling resistance, E3S Web of Conferences. Vol. 29. EDP Sciences (2018). https://doi.org/10.1051/e3sconf/20182900001 [13] P.W. Robinson, and C.A. Wheeler, The indentation rolling resistance of spherically profiled idler rolls, Int. J. Mech. Sci. 106 (2016): 363-371. https://doi.org/10.1016/j.ijmecsci.2015.12.001 [14] J.I. O’Shea, and C.A. Wheeler, Dielectric relaxation studies of conveyor belt compounds to determine indentation rolling resistance, Int. J. Mech. Mater. Des. 13.4 (2017): 553-567. [15] Y. Lu, F.-Y. Lin, and Y.-C. Wang, Investigation on influence of speed on rolling resistance of belt conveyor based on viscoelastic properties, J. Theoret. Appl. Mech. 45.3 (2015): 53-68. https://doi.org/10.1515/jtam-2015-0017 [16] C. Wheeler, and P. Munzenberger, Indentation rolling resistance measurement. Retrieved May 4 (2016). [17] M.A. Lodder, A survey of indentation rolling resistance models for belt conveyors-Een overzicht van vervormingsrolweerstand modellen in riemtransport systemin, (2017). [18] D. Woźniak, L. Gładysiewicz, and M. Konieczna, Experimental tests of the impact of selected parameters on the indentation rolling resistances. E3S Web of Conferences. Vol. 29. EDP Sciences (2018). https://doi.org/10.1051/e3sconf/20182900002 [19] P. Munzenberger, and C. Wheeler, Laboratory measurement of the indentation rolling resistance of conveyor belts, Meas. 94 (2016): 909-918. https://doi.org/10.1016/j.measurement.2016.08.030 [20] DIN EN 16974:2016 Conveyor belts - Indentation rolling resistance related to belt width Requirements, testing; German version EN 16974 (2016). [21] AS 1334.13:2017 Methods of testing conveyor and elevator belting Determination of indentation rolling resistance of conveyor belting; Standards Australia (2017). [22] A.V. Reicks, T.J. Rudolphi, and C.A. Wheeler, Science-A Comparison of Calculated and Measured Indentation Losses in Rubber Belt Covers, Bulk Solid. Handl. 32.3 (2012): 52. [23] V. Molnár, et al., Online monitoring of pipe conveyors part II: Evaluation of selected operational parameters for the design of expert system, Meas. 104 (2017): 1-11. https://doi.org/10.1016/j.measurement.2017.03.011 [24] ABNT 6678:2018 Continuous mechanical handling equipment - Belt conveyors - Idlers Design, selection and standardization; Standards Brazil (2018). [25] Y. Lu, and F. Lin, A study of indentation rolling resistance to motion of conveyor belts using a generalized Maxwell model of the backing material, Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol. 230.8 (2016): 1006-1018. https://doi.org/10.1177/1350650115622778 [26] S. Drenkelford, Energy-saving potential of Aramid-based conveyor belts, (2015). [27] S. Zamorano, Reducing energy consumption on overland conveyors, Eng. Mining J. 210.5 (2009): 58. [28] C. Wheller et al., Energy Efficient Belt Conveyor Design. TUNRA Bulk Solids Research Associates: The University of Newcastle, Australia. 27p. (2018).
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Title page for manuscript
December 20, 2019 Editorial Department of the Journal of the International Measurement Confederation Mr. P. Sivakumar Dear Mr. P. Sivakumar, This is the title page for manuscript MEASUR 107413 TITLE OF THE SUBMITTED MANUSCRIPT:
Development of idler for measuring indentation rolling resistance in pipe conveyor belts.
LIST OF ALL AUTHORS’ NAMES AND AFFILIATIONS: M.Eng. Leonardo dos Santos e Santos, Postgraduate Program in Process Engineering (PPGEP) at the Federal University of Pará (UFPA) orcid: 0000 0002 2038 1184 [email protected] +55 98 9 9161 5511 (personal mobile)
São Luís, Maranhão, Brazil
M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho, Mechanical Engineering Department at the State University of Maranhão (UEMA) orcid: 0000 0002 6066 1041 [email protected]
D.Sc. Emanuel Negrão Macêdo, Postgraduate Program in Process Engineering (PPGEP) at the Federal University of Pará (UFPA) orcid: 0000 0002 4652 8316 [email protected]
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Manuscript title: Development of idler for measuring indentation rolling resistance in pipe conveyor belts
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Highlights
Development of a low-cost method for measuring pipe-belt-conveyor indentation Designing, fabricating, and assembling a load idler in accordance with ABNT NBR 6678: 2018 Electronic module embedded in the measuring idler Effect of operating conditions on indentation value.
Declaration of interests
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Author’s name M.Eng. Leonardo dos Santos e Santos M.Eng. Paulo Roberto Campos Flexa Ribeiro Filho D.Sc. Emanuel Negrão Macêdo
Affiliation