- Email: [email protected]
Development of infrared radiation pyrometer with optical fibers—Two-color pyrometer with non-contact fiber coupler
CIRP Annals - Manufacturing Technology 57 (2008) 69–72
Contents lists available at ScienceDirect
CIRP Annals - Manufacturing Technology journal homepage: http://ees.elsevier.com/cirp/default.asp
Development of infrared radiation pyrometer with optical fibers —Two-color pyrometer with non-contact fiber coupler T. Ueda (2)a,*, M. Sato b, A. Hosokawa a, M. Ozawa a a b
Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan Department of Mechanical Engineering, Tottori University, Tottori, Japan
A R T I C L E I N F O
A B S T R A C T
Keywords: Cutting Temperature IR measurement
A new type of pyrometer is developed, in which two optical fibers are used to accept and transmit the infrared energy. These two fibers are connected using a non-contact fiber coupler. In turning, the incidence face of one optical fiber which is embedded in a rotating workpiece accepts the infrared rays radiated from the cutting tool and emits it at the other face. The infrared energy is accepted by the other optical fiber which is fixed at the pyrometer and led to the two-color detector. In endmilling, the temperature history of CBN tool face during cutting is measured, where the fiber is embedded in the endmill. ß 2008 CIRP.
1. Introduction The temperature measurement in material removal operation is an important approach to investigate cutting mechanism, tool wear, cutting accuracy, surface integrity of work materials and so on. Thermocouple technique and thermographic technique have been used commonly to measure the cutting temperature in turning, milling, drilling and grinding [1]. Recently, the authors made a new type of infrared radiation pyrometer, in which the infrared rays radiated from the object are accepted by an optical fiber and transmitted to the infrared detector and are then converted to an electric signal. Using this pyrometer, we measured the temperature of cutting grits on the wheel work surface and the temperature distribution in ceramics grinding. These temperatures are impossible to measure using the thermocouple technique [2,3]. Moreover, we can measure the temperature of endmill and the irradiation temperature with laser beam by using the two-color pyrometer in which an optical fiber is combined with the two-color detector [4,5]. This pyrometer makes it possible to measure the temperature without emissivity of the object affecting the result. In the present study, the newer type of infrared radiation pyrometer is developed and applied to measure the tool temperatures in turning and endmilling. In turning, the incidence face of one optical fiber which is embedded in a workpiece accepts the infrared rays radiated from the cutting tool. The infrared rays accepted by the embedded optical fiber which is rotating with the workpiece are transmitted and emitted at the other face of the optical fiber. The infrared energy is accepted by the other optical fiber which is fixed at the pyrometer and led to the two-color detector, and converted to the electric signal. The embedded optical fiber and the fixed optical fiber are connected using non-
* Corresponding author. 0007-8506/$ – see front matter ß 2008 CIRP. doi:10.1016/j.cirp.2008.03.056
contact fiber coupler. This new type pyrometer is also applied to measure the temperature of the cutting edge in endmilling. The optical fiber is embedded in the rotating endmill and the temperature history of CBN tool face during cutting is measured. 2. Experimental procedure 2.1. Turning 2.1.1. Temperature measurement system A schematic illustration of the experimental setup is shown in Fig. 1. A cylindrical workpiece is griped by the chuck of lathe and it is rotated by the main spindle. Chalcogenide glass fiber-A is embedded in the workpiece and the incidence face of the fiber is inserted into a small hole which extends to the outer surface of the cylindrical workpiece. The diameter of the small hole is 1.1 mm and the distance between the incidence face of the optical fiber and the machined surface of the workpiece is 0.5 mm. The incidence face of optical fiber-A which rotates with the workpiece accepts the infrared rays radiated from the flank face of the tool tip when the incidence face of fiber-A passes through the tool tip during cutting operation. The weight of optical fiber-A is so light that the influence of the inertia on acquiring signal can be negligible. The infrared rays accepted by optical fiber-A are transmitted and emitted at the other face of optical fiber-A. The infrared rays are accepted by fiber-B which is fixed at the pyrometer and led to the two-color detector. These two optical fibers are connected with the non-contact fiber coupler with the distance between the two fibers 0.1 mm. The infrared energy is converted to electric signals by the two-color detector which consists of InAs and InSb detectors. The InAs detector is mounted in a sandwich configuration over an InSb detector. The InAs detector responds to incident radiation from 1 to 3 mm and transmits waves larger than 3 mm, while the InSb detector responds to radiation from 3 to 5 mm. Taking the ratio of these two output voltages, and using the calibration curve, we can
70
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
Fig. 1. Experimental setup of tool face temperature measurement in turning.
get the temperature. Taking the ratio makes it possible to cancel the small disturbance in output voltages, so that this pyrometer can be used to measure the temperature in oil mist cutting. 2.1.2. Experimental conditions The cutting experiments are performed under the conditions shown in Table 1. As workpiece materials, chromium–molybdenum steel AISI 4140 and pearlite malleable cast iron ASTM A220 are used. As cutting tools, TiCN-coated cermet is used for AISI 4140 and alumina ceramics for ASTM A220. In experiments, cutting speed, feed rate and depth of cut are changed and the temperature of tool tip at flank face is measured using two-color pyrometer with non-contact fiber coupler and three cutting forces are measured using the elastic dynamometer.
2.2.2. Experimental conditions The cutting experiments are performed under the conditions shown in Table 2. As a work material, 0.55% carbon steel is used and as a cutting tool, binderless CBN tip (Fig. 3) is used. In experiments, cutting speed is changed from 132 to 264 m/min and both up cutting and down cutting are performed. The workpiece is mounted on the piezoelectric dynamometer and cutting forces of three components are measured.
2.2. Milling
3. Non-contact fiber coupler
2.2.1. Temperature measurement system A schematic illustration of the experimental setup is shown in Fig. 2. A single point endmilling cutter is used and an optical fiber is embedded in the shank. The tool insert is made by bonding the binderless CBN tip to a cemented carbide substrate. The detail of the tool insert is indicated in Fig. 2 and the thickness of CBN tip is 0.65 mm. The spectral transmittance of the CBN tip used in this experiment is shown in Fig. 3. The tool insert of carbide has a small hole which is drilled from underneath until the bottom of the hole reached the surface of CBN tip. The fluoride glass fiber is inserted into the hole until the incidence face of the fiber reaches the under surface of CBN tip. The infrared rays radiated from the interface between the rake face of CBN tip and the chip and transmitted through the CBN tip are accepted by the embedded optical fiber-A which is rotating with the shank bar. Optical fiber-A is connected to optical fiber-B by the non-contact fiber coupler, so that the infrared rays transmitted by optical fiber-A are accepted by optical fiber-B and led to the two-color detector and the infrared energy is converted to the electric signals. Taking the ratio of these two output voltages and using the calibration curve, we can get the temperature.
The positional relationship of the non-contact fiber coupler is shown in Fig. 4. In the figure, ‘a’ shows the fiber deviation between the rotational center axis and fiber-B and ‘e’ the eccentricity between fiber-A and the rotational center axis. Ideally, fiber-A is on the same axis of fiber-B and rotates without runout in the coupler. In a practical case, ‘a’ and ‘e’ are not zero, so that the effects of deviation and eccentricity on the transmission energy are investigated theoretically and experimentally. Here fiber-B is set at a distance of ‘t’ from the radiating face of fiber-A. Only rays which are incident on the face of fiber-B’s core at an angle less than the acceptance angle of jmax can be transmitted. Therefore, fiber-B can accept only rays radiated from its target area on the radiating face of fiber-A. In the figure, the energy del from df incident on dF is expressed by the following expression:
Table 1 Experimental conditions in turning Workpiece: AISI 4140 (350 HV0.5) Cutting tool
Cutting speed Depth of cut Feed Workpiece: ASTM A220 (310 HV0.5) Cutting tool
Cutting speed Depth of cut Feed Optical fiber: chalcogenide glass fiber
Fig. 2. Experimental setup of temperature measurement in milling.
del ¼ Jðl; TÞ dl cos f d f dV
(1)
where J(l,T) is the normal spectral radiant intensity, l is the wavelength of the infrared ray, T is the temperature of df, f is the angle between the normal line and R, R is the distance between df and dF, and dV is the solid angle of dF. Therefore, the total radiant energy El is expressed by: El ¼
ZZ
Jðl; TÞ dl
cos2 f R2
dF d f
TNGM 160408 Nose radius: 0.8 mm, rake angle: 68 Insert: TiCN-coated cermet v = 30–300 m/min a = 0.5 mm f = 0.3 mm/rev
DNGA 150408 Nose radius: 0.8 mm, rake angle: 68 Insert: alumina ceramics v = 100–600 m/min a = 0.10–0.35 mm f = 0.10–0.25 mm/rev Fig. 3. Spectral transmittance of binderless CBN tip.
(2)
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
71
Table 2 Experimental conditions in endmilling Workpiece: 0.55% carbon steel Cutting tool (tool tip)
Cutting speed Axial depth of cut Radial depth of cut Feed Cutting fluid
Binderless CBN Radial rake angle: 38 Axial rake angle: 08 Diameter of cutter: 52 mm v = 132–264 m/min 2 mm 3 mm 0.2 mm/tooth None
Optical fiber: fluoride glass fiber
The effects of deviation and eccentricity on the transmission energy from fiber-A to fiber-B calculated by Eq. (2) are shown in Fig. 5(a), when the deviation is 20 mm. The abscissa represents the rotational angle of fiber-A and the ordinate represents the relative transmission energy from fiber-A to fiber-B. The relative transmission energy when there is no deviation and eccentricity between the fibers is expressed at unity. For instance, when the deviation is 20 mm and the eccentricity is 40 mm, the relative transmission energy varies periodically in the range from 0.6 to 0.8. Incidentally, the two-color pyrometer converts the output ratio of signals from these photocells into temperature. Since the variations of incident infrared radiation energy to each photocell caused by deviation and eccentricity are exactly the same, their effects are cancelled in the process of taking the ratio. Consequently, the two-color pyrometer compensates for measurement errors ascribed to deviations and eccentricities between fibers. We experimentally confirm the independence of the twocolor pyrometer from deviation and eccentricity between the fibers in the coupler. The output voltage of the pyrometer is measured when it accepts the infrared rays from the specimen which is heated to a constant temperature. The result is shown in Fig. 5(b). The abscissa axis represents the rotational angle of the rod and the ordinate axis represents the output voltage of InAs detector and that of InSb detector, and the output ratio of these detectors. The output voltages of InAs detector and InSb detector vary periodically due to deviation and eccentricity between the fibers, but the output ratio of InAs/InSb is almost constant. This means that the output ratio of InAs detector and InSb detector is independent of deviation and eccentricity between the fibers.
Fig. 4. Illustration of non-contact fiber coupler.
Fig. 5. Effect of deviation and eccentricity between two optical fibers in non-contact fiber coupler on the output voltage of two-color detector. (a) Theoretical and (b) experimental.
4. Experimental results 4.1. Turning 4.1.1. Output wave Fig. 6 shows the typical output waves of two-color pyrometer. The upper figure represents the output voltage from InAs detector and the lower figure represents that from InSb detector. There are some pulses in each figure. These pulses are measured when the cutting edge passes above the small hole in the workpiece and the optical fiber which is embedded in the workpiece accepts the infrared rays radiated from the cutting tool and transmits them to the two-color detector through the non-contact fiber coupler. The period between these two pulses is 40 ms and this time corresponds to one revolution of the work material. We can get the temperature at the flank face of cutting tip by taking the ratio of these two output voltages and using the calibration curve. 4.1.2. Influence of cutting conditions on tool temperature The influence of cutting conditions on tool temperature at flank face is shown in Fig. 7. Fig. 7(a) shows the tool temperature at the flank face as a function of cutting speed. The work material AISI 4140 is cut with TiCN-coated cermet and ASTM A220 with alumina ceramics. In both cases, the tool temperature increases with increase of cutting speed. The tool temperature of AISI 4140 is much higher than that of ASTM A220 because the machinability of ASTM A220 is superior to that of AISI 4140. At cutting speed 200 m/ min the tool temperature of AISI 4140 is approximately 1000 8C and that of ASTM A220 is approximately only 700 8C. It is possible
Fig. 6. Output wave of two-color pyrometer in turning.
72
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
Fig. 7. Influence of cutting conditions on tool temperature. (a) Cutting speed, (b) feed rate and (c) depth of cut.
5. Conclusions
Fig. 8. Comparison of output waves of InAs detector between up cutting and down cutting (cutting speed = 264 m/min). (a) Up cutting and (b) down cutting
to be cut ASTM A220 with a cutting speed of 600 m/min and tool temperature of approximately 950 8C. Fig. 7(b) and (c) shows the tool temperatures as a function of feed rate and depth of cut, respectively. As feed rate increases, the tool temperature increases gradually. However, the influence of depth of cut on tool temperature is lower than that of feed rate. The cutting forces increase almost linearly with the increase of depth of cut, but it can be considered that a large part of the heat generated in cutting is removed by the chip. Consequently, the effects of depth of cut and feed rate on the tool temperature are not as great as the effect of the cutting speed. 4.2. Milling 4.2.1. Output wave and tool temperature Fig. 8 shows the output signals of InAs detector in endmilling. Fig. 8(a) represents the output voltage of InAs detector when up cutting and Fig. 8(b) represents the output voltage when down cutting is performed. In the case of up cutting, the output voltage of the detector increases gradually as the cutting proceeds and reach the maximum value at the end of cutting. This is because the depth of cut of CBN tip increases as the cutting proceeds. In the case of down cutting, the output voltage increases quickly at the beginning of cutting compared with that in up cutting. This is because the depth of cut of CBN tip is large at the beginning of cutting and decreases as cutting proceeds. Taking the ratio of output voltages of InAs detector and InSb detector (in this paper, this output wave is not indicated), we can get the temperature of the cutting tool at the rake face of CBN chip in cutting. The maximum temperature is 557 8C in up cutting and 627 8C in down cutting. Therefore, in down cutting, the tool temperature is approximately 70 8C higher than that in up cutting.
In this paper, a new type of infrared radiation pyrometer is developed and applied it to measure the tool temperature in turning and endmilling. In turning, the incidence face of the optical fiber which is embedded in a workpiece accepts the infrared rays radiated from the cutting tool. In endmilling, the optical fiber is embedded in the rotating endmill and the temperature history of CBN tool face is measured. The main results obtained are as follows. 1. Infrared radiation pyrometer with two optical fibers is developed, in which a non-contact fiber coupler is used and it makes it possible to transmit the infrared rays which is radiated from the optical fiber embedded in the rotational material to the other optical fiber which is fixed at the pyrometer. 2. Using the new pyrometer, the tool temperature at the flank face is measured in turning. In cutting of ASTM A220, the tool temperature is approximately 700 8C at cutting speed 200 m/ min and the temperature increases 950 8C as the cutting speed increases to 600 m/min. In cutting of AISI 4140, the tool temperature is approximately 1100 8C at cutting speed 300 m/ min. 3. This pyrometer makes it possible to measure the temperature history of CBN tip at rake face in endmilling. In up cutting, the tool temperature increases gradually and in down cutting, the temperature increases rapidly at the beginning of cutting. The maximum temperature is 557 8C in up cutting and 627 8C in down cutting, so that there is approximately 70 8C difference between up cutting and down cutting.
References [1] Davies MA, Ueda T, M’Saoubi R, Mullany B, Cooke AL (2007) On The Measurement of Temperature in Material Removal Processes. Annals of the CIRP 56(2):581–604. [2] Ueda T, Hosokawa A, Yamamoto A (1985) Studies on Temperature of Abrasive Grains in Grinding (Application of Infrared Radiation Pyrometer). ASME 107:127–133. [3] Ueda T, Yamada K, Sugita T (1992) Measurement of Grinding Temperature of Ceramics Using Infrared Radiation Pyrometer. ASME 114:317–322. [4] Ueda T, Yamada K, Nakayama K (1997) Temperature of Work Materials Irradiated with CO2 Laser. Annals of the CIRP 46(1):117–122. [5] Ueda T, Hosokawa A, Oda K, Yamada K (2001) Temperature on Flank Face of Cutting Tool in High Speed Milling. Annals of CIRP 50(1):37–40.
Contents lists available at ScienceDirect
CIRP Annals - Manufacturing Technology journal homepage: http://ees.elsevier.com/cirp/default.asp
Development of infrared radiation pyrometer with optical fibers —Two-color pyrometer with non-contact fiber coupler T. Ueda (2)a,*, M. Sato b, A. Hosokawa a, M. Ozawa a a b
Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan Department of Mechanical Engineering, Tottori University, Tottori, Japan
A R T I C L E I N F O
A B S T R A C T
Keywords: Cutting Temperature IR measurement
A new type of pyrometer is developed, in which two optical fibers are used to accept and transmit the infrared energy. These two fibers are connected using a non-contact fiber coupler. In turning, the incidence face of one optical fiber which is embedded in a rotating workpiece accepts the infrared rays radiated from the cutting tool and emits it at the other face. The infrared energy is accepted by the other optical fiber which is fixed at the pyrometer and led to the two-color detector. In endmilling, the temperature history of CBN tool face during cutting is measured, where the fiber is embedded in the endmill. ß 2008 CIRP.
1. Introduction The temperature measurement in material removal operation is an important approach to investigate cutting mechanism, tool wear, cutting accuracy, surface integrity of work materials and so on. Thermocouple technique and thermographic technique have been used commonly to measure the cutting temperature in turning, milling, drilling and grinding [1]. Recently, the authors made a new type of infrared radiation pyrometer, in which the infrared rays radiated from the object are accepted by an optical fiber and transmitted to the infrared detector and are then converted to an electric signal. Using this pyrometer, we measured the temperature of cutting grits on the wheel work surface and the temperature distribution in ceramics grinding. These temperatures are impossible to measure using the thermocouple technique [2,3]. Moreover, we can measure the temperature of endmill and the irradiation temperature with laser beam by using the two-color pyrometer in which an optical fiber is combined with the two-color detector [4,5]. This pyrometer makes it possible to measure the temperature without emissivity of the object affecting the result. In the present study, the newer type of infrared radiation pyrometer is developed and applied to measure the tool temperatures in turning and endmilling. In turning, the incidence face of one optical fiber which is embedded in a workpiece accepts the infrared rays radiated from the cutting tool. The infrared rays accepted by the embedded optical fiber which is rotating with the workpiece are transmitted and emitted at the other face of the optical fiber. The infrared energy is accepted by the other optical fiber which is fixed at the pyrometer and led to the two-color detector, and converted to the electric signal. The embedded optical fiber and the fixed optical fiber are connected using non-
* Corresponding author. 0007-8506/$ – see front matter ß 2008 CIRP. doi:10.1016/j.cirp.2008.03.056
contact fiber coupler. This new type pyrometer is also applied to measure the temperature of the cutting edge in endmilling. The optical fiber is embedded in the rotating endmill and the temperature history of CBN tool face during cutting is measured. 2. Experimental procedure 2.1. Turning 2.1.1. Temperature measurement system A schematic illustration of the experimental setup is shown in Fig. 1. A cylindrical workpiece is griped by the chuck of lathe and it is rotated by the main spindle. Chalcogenide glass fiber-A is embedded in the workpiece and the incidence face of the fiber is inserted into a small hole which extends to the outer surface of the cylindrical workpiece. The diameter of the small hole is 1.1 mm and the distance between the incidence face of the optical fiber and the machined surface of the workpiece is 0.5 mm. The incidence face of optical fiber-A which rotates with the workpiece accepts the infrared rays radiated from the flank face of the tool tip when the incidence face of fiber-A passes through the tool tip during cutting operation. The weight of optical fiber-A is so light that the influence of the inertia on acquiring signal can be negligible. The infrared rays accepted by optical fiber-A are transmitted and emitted at the other face of optical fiber-A. The infrared rays are accepted by fiber-B which is fixed at the pyrometer and led to the two-color detector. These two optical fibers are connected with the non-contact fiber coupler with the distance between the two fibers 0.1 mm. The infrared energy is converted to electric signals by the two-color detector which consists of InAs and InSb detectors. The InAs detector is mounted in a sandwich configuration over an InSb detector. The InAs detector responds to incident radiation from 1 to 3 mm and transmits waves larger than 3 mm, while the InSb detector responds to radiation from 3 to 5 mm. Taking the ratio of these two output voltages, and using the calibration curve, we can
70
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
Fig. 1. Experimental setup of tool face temperature measurement in turning.
get the temperature. Taking the ratio makes it possible to cancel the small disturbance in output voltages, so that this pyrometer can be used to measure the temperature in oil mist cutting. 2.1.2. Experimental conditions The cutting experiments are performed under the conditions shown in Table 1. As workpiece materials, chromium–molybdenum steel AISI 4140 and pearlite malleable cast iron ASTM A220 are used. As cutting tools, TiCN-coated cermet is used for AISI 4140 and alumina ceramics for ASTM A220. In experiments, cutting speed, feed rate and depth of cut are changed and the temperature of tool tip at flank face is measured using two-color pyrometer with non-contact fiber coupler and three cutting forces are measured using the elastic dynamometer.
2.2.2. Experimental conditions The cutting experiments are performed under the conditions shown in Table 2. As a work material, 0.55% carbon steel is used and as a cutting tool, binderless CBN tip (Fig. 3) is used. In experiments, cutting speed is changed from 132 to 264 m/min and both up cutting and down cutting are performed. The workpiece is mounted on the piezoelectric dynamometer and cutting forces of three components are measured.
2.2. Milling
3. Non-contact fiber coupler
2.2.1. Temperature measurement system A schematic illustration of the experimental setup is shown in Fig. 2. A single point endmilling cutter is used and an optical fiber is embedded in the shank. The tool insert is made by bonding the binderless CBN tip to a cemented carbide substrate. The detail of the tool insert is indicated in Fig. 2 and the thickness of CBN tip is 0.65 mm. The spectral transmittance of the CBN tip used in this experiment is shown in Fig. 3. The tool insert of carbide has a small hole which is drilled from underneath until the bottom of the hole reached the surface of CBN tip. The fluoride glass fiber is inserted into the hole until the incidence face of the fiber reaches the under surface of CBN tip. The infrared rays radiated from the interface between the rake face of CBN tip and the chip and transmitted through the CBN tip are accepted by the embedded optical fiber-A which is rotating with the shank bar. Optical fiber-A is connected to optical fiber-B by the non-contact fiber coupler, so that the infrared rays transmitted by optical fiber-A are accepted by optical fiber-B and led to the two-color detector and the infrared energy is converted to the electric signals. Taking the ratio of these two output voltages and using the calibration curve, we can get the temperature.
The positional relationship of the non-contact fiber coupler is shown in Fig. 4. In the figure, ‘a’ shows the fiber deviation between the rotational center axis and fiber-B and ‘e’ the eccentricity between fiber-A and the rotational center axis. Ideally, fiber-A is on the same axis of fiber-B and rotates without runout in the coupler. In a practical case, ‘a’ and ‘e’ are not zero, so that the effects of deviation and eccentricity on the transmission energy are investigated theoretically and experimentally. Here fiber-B is set at a distance of ‘t’ from the radiating face of fiber-A. Only rays which are incident on the face of fiber-B’s core at an angle less than the acceptance angle of jmax can be transmitted. Therefore, fiber-B can accept only rays radiated from its target area on the radiating face of fiber-A. In the figure, the energy del from df incident on dF is expressed by the following expression:
Table 1 Experimental conditions in turning Workpiece: AISI 4140 (350 HV0.5) Cutting tool
Cutting speed Depth of cut Feed Workpiece: ASTM A220 (310 HV0.5) Cutting tool
Cutting speed Depth of cut Feed Optical fiber: chalcogenide glass fiber
Fig. 2. Experimental setup of temperature measurement in milling.
del ¼ Jðl; TÞ dl cos f d f dV
(1)
where J(l,T) is the normal spectral radiant intensity, l is the wavelength of the infrared ray, T is the temperature of df, f is the angle between the normal line and R, R is the distance between df and dF, and dV is the solid angle of dF. Therefore, the total radiant energy El is expressed by: El ¼
ZZ
Jðl; TÞ dl
cos2 f R2
dF d f
TNGM 160408 Nose radius: 0.8 mm, rake angle: 68 Insert: TiCN-coated cermet v = 30–300 m/min a = 0.5 mm f = 0.3 mm/rev
DNGA 150408 Nose radius: 0.8 mm, rake angle: 68 Insert: alumina ceramics v = 100–600 m/min a = 0.10–0.35 mm f = 0.10–0.25 mm/rev Fig. 3. Spectral transmittance of binderless CBN tip.
(2)
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
71
Table 2 Experimental conditions in endmilling Workpiece: 0.55% carbon steel Cutting tool (tool tip)
Cutting speed Axial depth of cut Radial depth of cut Feed Cutting fluid
Binderless CBN Radial rake angle: 38 Axial rake angle: 08 Diameter of cutter: 52 mm v = 132–264 m/min 2 mm 3 mm 0.2 mm/tooth None
Optical fiber: fluoride glass fiber
The effects of deviation and eccentricity on the transmission energy from fiber-A to fiber-B calculated by Eq. (2) are shown in Fig. 5(a), when the deviation is 20 mm. The abscissa represents the rotational angle of fiber-A and the ordinate represents the relative transmission energy from fiber-A to fiber-B. The relative transmission energy when there is no deviation and eccentricity between the fibers is expressed at unity. For instance, when the deviation is 20 mm and the eccentricity is 40 mm, the relative transmission energy varies periodically in the range from 0.6 to 0.8. Incidentally, the two-color pyrometer converts the output ratio of signals from these photocells into temperature. Since the variations of incident infrared radiation energy to each photocell caused by deviation and eccentricity are exactly the same, their effects are cancelled in the process of taking the ratio. Consequently, the two-color pyrometer compensates for measurement errors ascribed to deviations and eccentricities between fibers. We experimentally confirm the independence of the twocolor pyrometer from deviation and eccentricity between the fibers in the coupler. The output voltage of the pyrometer is measured when it accepts the infrared rays from the specimen which is heated to a constant temperature. The result is shown in Fig. 5(b). The abscissa axis represents the rotational angle of the rod and the ordinate axis represents the output voltage of InAs detector and that of InSb detector, and the output ratio of these detectors. The output voltages of InAs detector and InSb detector vary periodically due to deviation and eccentricity between the fibers, but the output ratio of InAs/InSb is almost constant. This means that the output ratio of InAs detector and InSb detector is independent of deviation and eccentricity between the fibers.
Fig. 4. Illustration of non-contact fiber coupler.
Fig. 5. Effect of deviation and eccentricity between two optical fibers in non-contact fiber coupler on the output voltage of two-color detector. (a) Theoretical and (b) experimental.
4. Experimental results 4.1. Turning 4.1.1. Output wave Fig. 6 shows the typical output waves of two-color pyrometer. The upper figure represents the output voltage from InAs detector and the lower figure represents that from InSb detector. There are some pulses in each figure. These pulses are measured when the cutting edge passes above the small hole in the workpiece and the optical fiber which is embedded in the workpiece accepts the infrared rays radiated from the cutting tool and transmits them to the two-color detector through the non-contact fiber coupler. The period between these two pulses is 40 ms and this time corresponds to one revolution of the work material. We can get the temperature at the flank face of cutting tip by taking the ratio of these two output voltages and using the calibration curve. 4.1.2. Influence of cutting conditions on tool temperature The influence of cutting conditions on tool temperature at flank face is shown in Fig. 7. Fig. 7(a) shows the tool temperature at the flank face as a function of cutting speed. The work material AISI 4140 is cut with TiCN-coated cermet and ASTM A220 with alumina ceramics. In both cases, the tool temperature increases with increase of cutting speed. The tool temperature of AISI 4140 is much higher than that of ASTM A220 because the machinability of ASTM A220 is superior to that of AISI 4140. At cutting speed 200 m/ min the tool temperature of AISI 4140 is approximately 1000 8C and that of ASTM A220 is approximately only 700 8C. It is possible
Fig. 6. Output wave of two-color pyrometer in turning.
72
T. Ueda et al. / CIRP Annals - Manufacturing Technology 57 (2008) 69–72
Fig. 7. Influence of cutting conditions on tool temperature. (a) Cutting speed, (b) feed rate and (c) depth of cut.
5. Conclusions
Fig. 8. Comparison of output waves of InAs detector between up cutting and down cutting (cutting speed = 264 m/min). (a) Up cutting and (b) down cutting
to be cut ASTM A220 with a cutting speed of 600 m/min and tool temperature of approximately 950 8C. Fig. 7(b) and (c) shows the tool temperatures as a function of feed rate and depth of cut, respectively. As feed rate increases, the tool temperature increases gradually. However, the influence of depth of cut on tool temperature is lower than that of feed rate. The cutting forces increase almost linearly with the increase of depth of cut, but it can be considered that a large part of the heat generated in cutting is removed by the chip. Consequently, the effects of depth of cut and feed rate on the tool temperature are not as great as the effect of the cutting speed. 4.2. Milling 4.2.1. Output wave and tool temperature Fig. 8 shows the output signals of InAs detector in endmilling. Fig. 8(a) represents the output voltage of InAs detector when up cutting and Fig. 8(b) represents the output voltage when down cutting is performed. In the case of up cutting, the output voltage of the detector increases gradually as the cutting proceeds and reach the maximum value at the end of cutting. This is because the depth of cut of CBN tip increases as the cutting proceeds. In the case of down cutting, the output voltage increases quickly at the beginning of cutting compared with that in up cutting. This is because the depth of cut of CBN tip is large at the beginning of cutting and decreases as cutting proceeds. Taking the ratio of output voltages of InAs detector and InSb detector (in this paper, this output wave is not indicated), we can get the temperature of the cutting tool at the rake face of CBN chip in cutting. The maximum temperature is 557 8C in up cutting and 627 8C in down cutting. Therefore, in down cutting, the tool temperature is approximately 70 8C higher than that in up cutting.
In this paper, a new type of infrared radiation pyrometer is developed and applied it to measure the tool temperature in turning and endmilling. In turning, the incidence face of the optical fiber which is embedded in a workpiece accepts the infrared rays radiated from the cutting tool. In endmilling, the optical fiber is embedded in the rotating endmill and the temperature history of CBN tool face is measured. The main results obtained are as follows. 1. Infrared radiation pyrometer with two optical fibers is developed, in which a non-contact fiber coupler is used and it makes it possible to transmit the infrared rays which is radiated from the optical fiber embedded in the rotational material to the other optical fiber which is fixed at the pyrometer. 2. Using the new pyrometer, the tool temperature at the flank face is measured in turning. In cutting of ASTM A220, the tool temperature is approximately 700 8C at cutting speed 200 m/ min and the temperature increases 950 8C as the cutting speed increases to 600 m/min. In cutting of AISI 4140, the tool temperature is approximately 1100 8C at cutting speed 300 m/ min. 3. This pyrometer makes it possible to measure the temperature history of CBN tip at rake face in endmilling. In up cutting, the tool temperature increases gradually and in down cutting, the temperature increases rapidly at the beginning of cutting. The maximum temperature is 557 8C in up cutting and 627 8C in down cutting, so that there is approximately 70 8C difference between up cutting and down cutting.
References [1] Davies MA, Ueda T, M’Saoubi R, Mullany B, Cooke AL (2007) On The Measurement of Temperature in Material Removal Processes. Annals of the CIRP 56(2):581–604. [2] Ueda T, Hosokawa A, Yamamoto A (1985) Studies on Temperature of Abrasive Grains in Grinding (Application of Infrared Radiation Pyrometer). ASME 107:127–133. [3] Ueda T, Yamada K, Sugita T (1992) Measurement of Grinding Temperature of Ceramics Using Infrared Radiation Pyrometer. ASME 114:317–322. [4] Ueda T, Yamada K, Nakayama K (1997) Temperature of Work Materials Irradiated with CO2 Laser. Annals of the CIRP 46(1):117–122. [5] Ueda T, Hosokawa A, Oda K, Yamada K (2001) Temperature on Flank Face of Cutting Tool in High Speed Milling. Annals of CIRP 50(1):37–40.