- Email: [email protected]
3D roll forming center for automotive applications
Available online at www.sciencedirect.com Available online at www.sciencedirect.com
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Procedia Manufacturing 00 (2018) 000–000 Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procediaonline Manufacturing 00 (2018) 000–000
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www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Manufacturing 15 (2018) 767–774 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
17th International Conference on Metal Forming, Metal Forming 2018, 16-19 September 2018, 17th International Conference on MetalToyohashi, Forming, Metal Japan Forming 2018, 16-19 September 2018, Toyohashi, Japan
3D roll forming center for automotive applications
3D Engineering roll forming center for automotive applications Manufacturing Society International Conference 2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain Albert Sedlmaier*, Thomas Dietl Albert Sedlmaier*, Thomas Dietl
Costing models for capacity optimization in Industry 4.0: Trade-off between used capacity and operational efficiency Abstract Data M Sheet Metal Solutions GmbH, Valley 83626, Germnany Data M Sheet Metal Solutions GmbH, Valley 83626, Germnany
Abstract a,*as building blocks b Roll formed profiles are usedA. in automotive production forWernke the body-in-white. The ability to produce Santanaachassis , P. Afonso , A. Zaninb, R. Roll formed are usedcross in automotive chassis production building blocks for the body-in-white. Theautomotive ability to produce profiles withprofiles discontinuous sections, both in width and inas depth, allows weight savings in the final chassis a profiles withuse discontinuous cross cross sections, both This inofwidth and in depth, allows weight savings in the final automotive chassis University Minho, 4800-058 Guimarães, through the of load optimized sections. has been the target of the Portugal 3D Roll Forming process. A machine concept is b Unochapecó, 89809-000 Chapecó, SC, Brazil through the use of load optimized cross sections. This has been the target of the 3D Roll Forming process. A machine concept is presented where a new forming concept for roll formed parts in combination with advanced robotics allowing freely positioned presented where a new roll formed partsininroll combination with advanced robotics allowing freely positioned roll forming tooling in forming 3D spaceconcept enablesforrapid prototyping forming. This digitalization of manufacturing aims to take roll forming in 3D space enables rapid prototyping in roll forming. This digitalization manufacturing aims to take advantage of tooling advanced information and manufacturing technologies. Different types of sensors of (laser triangulation, force and advantage of advanced information and manufacturing technologies. Different of sensors (laser triangulation, and torque measurement sensors) are integrated, allowing the online monitoring of types the manufacturing process and of theforce machine Abstract torque measurement sensors) are integrated, allowing the online monitoring of the manufacturing process and of the machine itself. The new quality of measurement data in combination with machine learning algorithms lead to self-optimizing rollitself. The new quality of measurement data in combination with machine algorithms self-optimizing rollforming machines, increasing the productivity, quality and predictability of thelearning roll-forming process.lead Thetofirst parts successfully Under the concept ofnew"Industry 4.0", production willof be to be increasingly interconnected, forming machines, increasing the productivity, andprocesses predictability the pushed roll-forming process. The first parts successfully manufactured with this forming concept arequality presented. information on new a real time concept basis and, manufacturedbased with this forming are necessarily, presented. much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. © 2018 The Authors. Published by Elsevier B.V. © 2018 Authors. Published by Elsevier B.V. © 2018 The The Authors. Publishedand by Elsevier B.V. committee Indeed, lean management continuous improvement approaches suggest capacity optimization Peer-review under responsibility of the scientific of the 17th International Conference onMetal Metal Forming. instead of Peer-review under responsibility of the scientific committee of the 17th International Conference on Forming. Peer-review under responsibility of the scientific committee the 17thmodels International Metal Forming. maximization. The study of capacity optimization andofcosting is an Conference important on research topic that deserves
Keywords: Roll forming; Highthe tensile material;and Nonlinear simulation; Hybrid material; weight design; and 3D roll forming; Rapid prototyping contributions from both practical theoretical perspectives. ThisLight paper presents discusses a mathematical Keywords: Roll forming; High tensile material; Nonlinear simulation; Hybrid material; Light weight design; 3D roll forming; Rapid prototyping model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s 1. Introduction value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity 1. Introduction optimization might hide operational inefficiency. TheThe weight of a Published car or aircraft structure © 2017 Authors. by Elsevier B.V.is the predominant factor in terms of the reduction of emissions and fuel The weight[1]. of aAscarcan or be aircraft structure the predominant in of terms of thevehicle reductiondivided of emissions andbody, fuel consumption seen in Fig. 1,is around 75% ofManufacturing thefactor weight a motor between Peer-review under responsibility of the scientific committee of the Engineering SocietyisInternational Conference consumption [1]. As can be seen in Fig. 1, around 75% of the weight of a motor vehicle is divided between body, powertrain, suspension and chassis components. Reducing the weight of the body-in-white means smaller engines 2017. powertrain, suspension and chassis components. Reducing the weight of the body-in-white means smaller engines Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency
1. Introduction
* Corresponding author. Tel.: +49 8024 640-0; fax: +49 8024 640-300. * E-mail Corresponding Tel.: +49 8024 640-0; fax: +49 8024 640-300. address:author. [email protected] The cost of idle capacity is a fundamental information for companies and their management of extreme importance E-mail address: [email protected]
in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier 2351-9789 2018 Authors. Published Elsevier B.V.hours of Peer-review underThe responsibility of theby scientific committee of the 17th International on Metal of Forming. in several©ways: tons of production, available manufacturing, etc.Conference The management the idle capacity Peer-review under responsibility thefax: scientific committee * Paulo Afonso. Tel.: +351 253 510 of 761; +351 253 604 741 of the 17th International Conference on Metal Forming. E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. 10.1016/j.promfg.2018.07.319
Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Albert Sedlmaier/ Procedia Manufacturing 00 (2018) 000–000
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can be employed and smaller suspension systems are needed, so reducing the total weight of the body is crucial towards achieving lighter vehicles [2]. A possible approach to light weight design is to use high strength steels or aluminum, as well as new materials under research (for example, composites or multi-materials) [3]. A second approach is the application of load optimized design methods. By adapting the shape of different body-in-white components to the expected loads, savings of material can be made, reducing the overall mass of the body-in-white [4]. However, the resulting part geometries are usually not accessible to standard roll forming where only constant profile cross sections along the longitudinal axis of the profile can be manufactured [5].
Fig. 1. Breakdown of mass of passenger vehicle by components (approximate). [6]
The target of 3D Roll Forming is to widen the realm of possibilities in roll forming to include profiles with variable cross sections and so fulfill the demands of the automotive industry for more complex geometries. Moreover, traditional roll-forming lines make current profile production techniques inefficient for small-batch production, which is typical in the manufacture of high-value products (e.g. sports cars, SUVs or aircraft). 3D Roll Forming aims to open up new markets by enabling small production runs and rapid prototyping of profiles in a cost effective way [7]. The latest advances in 3D Roll Forming are only possible due to a well-established virtual process design chain, where a CAD system is used for the initial process design and simulations are generated for the process validation and the generation of optimized tool motion paths [7]. Any defects that would otherwise plague the completed system are also detected in an early design phase. The COPRA® system provides such an integrated process design approach, and can be seen as a digital roll forming mill, where different strategies can be tried out in a very short time and without any manufacturing costs [8]. Furthermore, the integration of various types of sensors for real time monitoring of the 3D Roll Forming process facilitates quick reactions to manufacturing problems due to the inherent flexibility of the process. This is also the first step towards the automatic correction of manufacturing defects through the use of machine learning algorithms and big data analysis [9]. Beyond the pure digitalization of the control units of production machines, great expectations are placed on the collection and analysis of data - a collection of topics often referred to as smart factories or industry 4.0. Roll forming is often perceived as somewhat trailing behind current trends in this area. This may be related to the comparative longevity of the roll forming machinery and the associated longer planning cycles for investments in production facilities. However, data M sees the potential for process improvements of these techniques, and even though the introduction of industry 4.0 in roll forming is a complex topic, a program to develop the necessary strategies and tools has been started. 2. Efficient planning tools In traditional roll forming of geometries with constant cross sections proven design-process-chains are being used. Starting point for the process design is a CAD system. The CAD model of the desired profile is the basis for the development of forming tools and a suitable forming machine, respectively.
Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Author name / Procedia Manufacturing 00 (2018) 000–000
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In the first steps, a so-called flower pattern is developed, defining the subsequent incremental bending steps from a flat strip to the final profile. The cross sections in each bending step are the basis for the following design of the required roll tooling. Tooling and machine parameters (distance of forming stands, distance of roll axes, stiffness of forming stands) are, in the next step, essentially the input to build a finite element model. The effort to build the finite element model is reduced to a minimum as highly specialized pre-processors are doing this job automatically directly from the CAD system. The simulation using special FEA-solvers allows for a quick validation of the modelled forming process. The tool engineers can thus easily investigate and benchmark different variants of forming strategies. Due to the fact that the (normally) time consuming and error-prone FEA modelling job has been eliminated, product development is accelerated substantially and product quality becomes predictable. The roll forming tooling can be optimized in iteration loops, considering factors such as product quality, the quality of the forming process itself (dimensional stability, surface finish, process stability…) as well as cost for tooling and cost for the whole production process (roll tool dimensions, number of forming steps required…). data M’s software package COPRA® is already providing a highly efficient workflow in the design and simulation process for classic roll forming.
Fig. 2. (a) COPRA® - Tool design and simulation software; (b) and (c) example of results of 3D roll forming simulation.
2.1. 3D roll forming Compared to “classic roll forming” the so-called “3D roll forming” widens the range of application by profile shapes having a variable cross section over its longitudinal axis. This necessitates also further development of the proven planning workflow and requires new tooling concepts. A single flower pattern for all subsequent forming steps is no longer sufficient to describe a 3D roll forming process. Instead it is necessary to develop individual flower patterns for every single cross sectional geometry occurring in the 3D profile have to be developed. This directly leads to the question of the correct sheet metal precut for profiles with variable cross sections. The various profile flower patterns take us to a first draft of the required pre-cut. The real size of sheet metal pre-cut has to be determined by some finite element simulation. This is because the forming strategy used has a decisive influence on the strip edges and thus on the contour of the incoming sheet strip.
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Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Albert Sedlmaier/ Procedia Manufacturing 00 (2018) 000–000
Subsequently multiple challenges are to follow regarding the roll forming line and its roll tooling concept. For instance - every single forming roll has to fit into different profile cross sections. The rolls are moving along the variably changing profile geometry in order to ensure a continuous forming. For a width-variable profile this means for instance a combination of rotational and translational movements within the profile’s flanges. This may lead to collisions between roll and profile or even between the rolls itself, if the tooling was not optimized in advance. Other challenges to be taken into account are the kinematic and dynamic behavior of the forming machine.
Fig. 3. Flower pattern of load-optimized profile.
Depending on the shape of the load matching profile to be produced the work space of all the roll forming stations should be determined. The maximum roll forming speed is limited by the dynamic behavior of the forming stand’s actuators. All these calculations are, for example, incorporated in the evaluation of economic efficiency and the dimensioning of electric drives or mechanical parts. 2.2. Process planning tools for 3D roll forming The process planning tools for 3D roll forming are based on the already established design-process-chain of COPRA®. The software module COPRA® RF assists in the design of profile flowers and forming rolls – also for load matching 3D profiles. A software interface offers the possibility to export the complete roll tooling to the 3D CAD system Autodesk® Inventor in order to conduct collision checks or fit into an existing machine design. The central point in the virtual process development is at this stage the finite element simulation software COPRA® FEA RF. This high-end simulation uses 3D hex-elements along with an implicit solver; which due to contact, material models and friction becomes highly non-linear. This software package has been extended (within the development of 3D roll forming) by adding kinematic modules allowing the 3D roll tool movement. The roll tool curves (trajectories) are derived from the 3D part geometry and transferred to the simulation program – for each single forming tool. The results of these simulations are providing detailed information about the feasibility of a 3D profile, for instance: • • • •
Expected profile quality with regard to geometrical issues (Flatness, warping, bending angles of flanges in transitional areas, deviations etc.) Is it advisable to modify the design of the required profile to better suit the roll form process? Often related to the transition zones between different cross sectional areas. Range of expected forming forces, driving torques or rotational speeds. Does this process fit into an already existing 3D roll forming line (with regard to roll diameter, distance of axes, forming forces, working space of flexible forming stands) or is it required to design a new mill?
For the conception of a new 3D roll forming mill the same planning instruments are used. However, due to the fact that the forming tools in a 3D RF mill are being moved through complex parallel kinematics, some classic engineering instruments cannot be applied immediately. Depending on the roll tool position in 3D space, loads on the actuators can change drastically. The feedback of forming forces on the behavior of the machine’s structure is thus of great importance.
Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Author name / Procedia Manufacturing 00 (2018) 000–000
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The solution for this challenge is the co-simulation between COPRA® FEA RF (a nonlinear FE software) and a multibody dynamics simulation software like MSC Adams®. This allows the engineer to study the dynamics of moving parts and loads and how loads and forces are distributed throughout the complex movement of rolling tools, resulting in drastic improvement of the quality of the machine design. At the same time, for the dimensioning of the actuators, data M’s engineers use control technology which has been developed specifically for roll forming lines: COPRA® Adaptive Motion Control. This software package is in its “virtual mode” assisting in the planning and dimensioning process for roll forming of 3D load matching profiles. In a first stage the kinematic devices of each forming station are parametrized in the control. The engineer inputs the trajectories of each station and starts some simulation run on the control. The control helps (for instance for a given roll forming speed) to determine the maximum axial or revolution speed of the motor drives. During the virtual forming process, the control records the changes of velocity in each forming stand. As the dynamic of each actuator and their maximum speed are limited, this method allows (considering all controlled axes) the determination of the maximum possible speed of the whole forming process. In other words: what will be the maximum roll forming speed. Based on this principle the motor drives of such a 3D roll forming line are being optimized which in turn leads to the final mechanical dimension of the machine and the electrical cabinets as well. Clearly these thoughts are taken into consideration in the commercial viability of the whole system.
Fig. 4. User interface of COPRA® Adaptive Motion Control.
3. Load optimized parts for commercial vehicles (trucks) Similarly to car manufacturers, producers of commercial vehicles also have an interest in light weight- and especially in load-optimized designs of their chassis frames. There is also interest in an increased number of possible variants in consequence of requirements for transportation, driving systems, special purpose vehicle bodies. Recently the author’s company has presented a 3D roll forming line for the production of chassis long members for trucks [9]. This mill allows for the production of a family of more than 50 long members with different profile geometries using only a single tool set. The high level of digitization reduces set-up time to almost zero. Simply the recipe- or program change, operated by the MES (Manufacturing Execution System) or locally by the operator, is required. The presented machine concept is highly flexible. Therefore the smallest or largest of batches can be produced at the minimum cost and utmost energy efficiency. Due to the use of the most advanced control technology along with specially developed parallel kinematic mechanics both geometrical and/or material changes can be compensated quickly. Another advantage of this method is the simple compensation of spring back by adaptation of only a few forming rolls, therefore allowing high tensile steels to be roll formed reliably. The open and flexible control concept with
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soft- and hardware-interfaces allows for an easy integration in existing production lines. Data transfer to or from ERP- or MES systems can be realized using OPC UA.
Fig. 5. (a) 3D roll forming line for truck beams developed by data M SMS with 96 simultaneously controlled axes; (b) example of chassis frame with load optimized long members.
Process- and machine data can be stored in local or cloud-based data bases in real-time. Thus allowing (based on this data) the future possibility to predict machine maintenance and availability periods as well as process robustness and product quality. 4. The 3D RollformingCenter® Traditional Roll Forming is usually not suitable for small lot sizes. However, these are common in the production of high-class products like sports cars, SUVs or aircrafts, meaning roll forming has been “locked out” from complex geometries with variable cross sections being used in the automotive industry. This is the reason for presenting a new machine- and forming concept. Using advanced robotics, roll forming tools can be positioned freely in space. The combination of modern control technology and simulation technology has led to digitization of the production process allowing for the production of smallest lot sizes of load-optimized and also classic profiles. Alternatively this concept can be used for rapid prototyping in roll forming as well as process development and optimization. There is also room for applications in material research – especially with regard to hybrid/ multi materials or high tensile materials. Furthermore, one of the positive advantages with this machine concept, are very low tooling costs, compared to other forming methods. 4.1. Description of forming method and machine
Fig. 6. A flat raw sheet is placed into die taking shape of profile’s web. Roll forming tools move along die (trajectories).
Like in an oversized bench vice with a prefabricated shape, the flat raw sheet strip is placed in a die, where the sheet already takes the shape of the profile’s web. The roll forming tools themselves then move along trajectories in order to form the profile’s flanges step by step around the top die – until the final profile shape is reached.
Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Author name / Procedia Manufacturing 00 (2018) 000–000
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4.2. Concept of machine The 3D RollformingCenter® could be likened to a roll form simulator – consisting of a single pair of forming stands. The sheet, clamped in a die and mounted on a linear slide, passes the roll forming stands in alternating direction. The roll forming stands (one on each side) are mounted on a robot which aligns the forming rolls into the correct forming position. Given a straight profile with constant cross section, the robot would not move during one forming process – it would just keep the rolls in their position. Just before the second forming cycle the rolls will be brought into their new bending position. Several bending operations can be done with one and the same rolls. The robots have a tool changing system for fast and precise tool changes during production. The 3D RollformingCenter® consists of a machine bed with a linear slide, hydraulically holding the driven upper and lower dies. Perpendicular to this slide are a pair of hexapod robots (left and right) each with moveable platforms holding the roll forming stands. The control system synchronizes the movements of the linear slide with the hexapods.
Fig. 7. 3D Roll Forming Center® with hexapod robots and roll tooling.
Forming a 3D Profile, the robots are changing their position while the linear slide is moving from left to right (or vice versa). The hexapod mechanism is able to follow every combination of translational or rotatory movements. The greatest advantage of this machine is its high flexibility due to the digitization of the roll forming tooling. The system can react instantly to changes in material behavior, for instance, by programming additional intermediate forming steps. By using this procedure, the forming of a width-variable profile was successfully optimized – without the need of changing the rolls or making new ones, instead just by reprogramming the robot’s bending angle. Several trials to form load matching parts on the 3D RollformingCenter® have been successfully carried out investigating two categories of profiles: firstly being variable in width and secondly with variation in height.
Fig. 8. Different automotive parts already produced on 3D RollformingCenter.
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Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Albert Sedlmaier/ Procedia Manufacturing 00 (2018) 000–000
4.3. Concept of industrial line With the 3D RollformingCenter® it is now possible to investigate and validate new concepts for industrial lines at a very early development stage. Profile quality, feasibility as well as prototype parts can be investigated in the forefront of any subsequent planning steps, both cost efficient and quickly. Concerning tooling, only the holding die (manufactured from simple material) and the usually very simple and small forming rolls have to be manufactured. At the author’s company a concept for high volume industrial production has been developed. In a first step, the part has been formed on the 3D RollformingCenter® and the whole forming process optimized. Additionally, by analyzing the profiles trajectories, the number of forming tools and the number of required degrees of freedom (controlled axis) could be reduced significantly in any future, proposed or planned 3D RF machine. 5. Outlook The first 3D RollformingCenter® has been shipped to a renowned Australian material research institute. The target of their investigation is new materials such as high tensile steels and their forming behavior. The concept of this prototyping machine is also suitable for the cost effective and flexible production, of small batches of profiles. Due to this highest flexible machine concept, both conventional as well as 3D geometries can be produced in a “rapid prototyping” manner. Further areas of interest are the development of innovative sensor technology for roll forming. At the author’s company a prototype of a new 3D laser triangulation sensor was developed. This is able to scan the full profile length in the machine. Along with respective control technology and integrated sensors the subject “big data” for roll forming 4.0 can get pushed forward. The author’s company is looking for industrial partners introducing this promising new technology. References [1] G. Fontaras, V. Franco, P. Dilara, G. Martini, U. Manfredi, Development and review of Euro 5 passenger car emission factors based on experimental results over various driving cycles, Science of the total environment, 468 (2014) 1034–1042. [2] L. Eckstein, R. Göbbelsist, M. Goede, T. Laue, R. Wohlecker, Analyse sekundärer gewichtseinsparpotenziale in kraftfahrzeugen, ATZ Automobiltechnische Zeitschrift, 113 (2011) 68–76. [3] H.E. Friedrich, D. Hülsebusch, Elektrofahrzeugkonzepte und leichtbau:anforderungen für neue werkstoffe?, Lightweight Design, 2 (2009) 18–24. [4] A. Sedlmaier, R. Hennig, A. Abee, Fabrication of load optimized truck members with variable cross sections by flexible roll forming, Proceedings International Conference on Steels in Cars and Trucks, Salzburg, (2011). [5] B. Abeyrathna, A. Abvabi, B. Rolfe, R. Taube, M. Weiss, Numerical analysis of the flexible roll forming of an automotive component from high strength steel, IOP Conference Series: Materials Science and Engineering, 159 (2016) 012005. [6] A. Mayyas, A. Qattawi, A.R. Mayyas, M.A. Omar, Life cycle assessment-based selection for a sustainable lightweight body-in-white design Energy, 39 (2012) 412–25. [7] A. Sedlmaier, T. Dietl, Recent advances in the industrial application of flexible (3D) roll forming for automotive parts by the use of modern CAE tools, Proceedings IDDRG 2015 Conference, Shanghai, (2015). [8] A. Abee, A. Sedlmaier, C. Stephenson, Development of new 3D roll forming applications by means of numerical analysis as a part of a quality control methodology, CBM Metal Matters, 18 (2010) 21–23. [9] T. Dietl, A. Sedlmaier, T. Schneider, Multiachs steuerungstechnik im einsatz für die herstellung von walzprofilen (mit 3D Konturen), Proceedings 36. EFB Kolloquium, Fellbach, (2016). [10] https://youtu.be/-ExYY8LfU9A [11] https://youtu.be/7I1EMPflBAw
ScienceDirect ScienceDirect
Procedia Manufacturing 00 (2018) 000–000 Available online atatwww.sciencedirect.com Available www.sciencedirect.com Procediaonline Manufacturing 00 (2018) 000–000
ScienceDirect ScienceDirect
www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Manufacturing 15 (2018) 767–774 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
17th International Conference on Metal Forming, Metal Forming 2018, 16-19 September 2018, 17th International Conference on MetalToyohashi, Forming, Metal Japan Forming 2018, 16-19 September 2018, Toyohashi, Japan
3D roll forming center for automotive applications
3D Engineering roll forming center for automotive applications Manufacturing Society International Conference 2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain Albert Sedlmaier*, Thomas Dietl Albert Sedlmaier*, Thomas Dietl
Costing models for capacity optimization in Industry 4.0: Trade-off between used capacity and operational efficiency Abstract Data M Sheet Metal Solutions GmbH, Valley 83626, Germnany Data M Sheet Metal Solutions GmbH, Valley 83626, Germnany
Abstract a,*as building blocks b Roll formed profiles are usedA. in automotive production forWernke the body-in-white. The ability to produce Santanaachassis , P. Afonso , A. Zaninb, R. Roll formed are usedcross in automotive chassis production building blocks for the body-in-white. Theautomotive ability to produce profiles withprofiles discontinuous sections, both in width and inas depth, allows weight savings in the final chassis a profiles withuse discontinuous cross cross sections, both This inofwidth and in depth, allows weight savings in the final automotive chassis University Minho, 4800-058 Guimarães, through the of load optimized sections. has been the target of the Portugal 3D Roll Forming process. A machine concept is b Unochapecó, 89809-000 Chapecó, SC, Brazil through the use of load optimized cross sections. This has been the target of the 3D Roll Forming process. A machine concept is presented where a new forming concept for roll formed parts in combination with advanced robotics allowing freely positioned presented where a new roll formed partsininroll combination with advanced robotics allowing freely positioned roll forming tooling in forming 3D spaceconcept enablesforrapid prototyping forming. This digitalization of manufacturing aims to take roll forming in 3D space enables rapid prototyping in roll forming. This digitalization manufacturing aims to take advantage of tooling advanced information and manufacturing technologies. Different types of sensors of (laser triangulation, force and advantage of advanced information and manufacturing technologies. Different of sensors (laser triangulation, and torque measurement sensors) are integrated, allowing the online monitoring of types the manufacturing process and of theforce machine Abstract torque measurement sensors) are integrated, allowing the online monitoring of the manufacturing process and of the machine itself. The new quality of measurement data in combination with machine learning algorithms lead to self-optimizing rollitself. The new quality of measurement data in combination with machine algorithms self-optimizing rollforming machines, increasing the productivity, quality and predictability of thelearning roll-forming process.lead Thetofirst parts successfully Under the concept ofnew"Industry 4.0", production willof be to be increasingly interconnected, forming machines, increasing the productivity, andprocesses predictability the pushed roll-forming process. The first parts successfully manufactured with this forming concept arequality presented. information on new a real time concept basis and, manufacturedbased with this forming are necessarily, presented. much more efficient. In this context, capacity optimization goes beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. © 2018 The Authors. Published by Elsevier B.V. © 2018 Authors. Published by Elsevier B.V. © 2018 The The Authors. Publishedand by Elsevier B.V. committee Indeed, lean management continuous improvement approaches suggest capacity optimization Peer-review under responsibility of the scientific of the 17th International Conference onMetal Metal Forming. instead of Peer-review under responsibility of the scientific committee of the 17th International Conference on Forming. Peer-review under responsibility of the scientific committee the 17thmodels International Metal Forming. maximization. The study of capacity optimization andofcosting is an Conference important on research topic that deserves
Keywords: Roll forming; Highthe tensile material;and Nonlinear simulation; Hybrid material; weight design; and 3D roll forming; Rapid prototyping contributions from both practical theoretical perspectives. ThisLight paper presents discusses a mathematical Keywords: Roll forming; High tensile material; Nonlinear simulation; Hybrid material; Light weight design; 3D roll forming; Rapid prototyping model for capacity management based on different costing models (ABC and TDABC). A generic model has been developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s 1. Introduction value. The trade-off capacity maximization vs operational efficiency is highlighted and it is shown that capacity 1. Introduction optimization might hide operational inefficiency. TheThe weight of a Published car or aircraft structure © 2017 Authors. by Elsevier B.V.is the predominant factor in terms of the reduction of emissions and fuel The weight[1]. of aAscarcan or be aircraft structure the predominant in of terms of thevehicle reductiondivided of emissions andbody, fuel consumption seen in Fig. 1,is around 75% ofManufacturing thefactor weight a motor between Peer-review under responsibility of the scientific committee of the Engineering SocietyisInternational Conference consumption [1]. As can be seen in Fig. 1, around 75% of the weight of a motor vehicle is divided between body, powertrain, suspension and chassis components. Reducing the weight of the body-in-white means smaller engines 2017. powertrain, suspension and chassis components. Reducing the weight of the body-in-white means smaller engines Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency
1. Introduction
* Corresponding author. Tel.: +49 8024 640-0; fax: +49 8024 640-300. * E-mail Corresponding Tel.: +49 8024 640-0; fax: +49 8024 640-300. address:author. [email protected] The cost of idle capacity is a fundamental information for companies and their management of extreme importance E-mail address: [email protected]
in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2018 The Authors. Published by Elsevier 2351-9789 2018 Authors. Published Elsevier B.V.hours of Peer-review underThe responsibility of theby scientific committee of the 17th International on Metal of Forming. in several©ways: tons of production, available manufacturing, etc.Conference The management the idle capacity Peer-review under responsibility thefax: scientific committee * Paulo Afonso. Tel.: +351 253 510 of 761; +351 253 604 741 of the 17th International Conference on Metal Forming. E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the 17th International Conference on Metal Forming. 10.1016/j.promfg.2018.07.319
Albert Sedlmaier et al. / Procedia Manufacturing 15 (2018) 767–774 Albert Sedlmaier/ Procedia Manufacturing 00 (2018) 000–000
768 2
can be employed and smaller suspension systems are needed, so reducing the total weight of the body is crucial towards achieving lighter vehicles [2]. A possible approach to light weight design is to use high strength steels or aluminum, as well as new materials under research (for example, composites or multi-materials) [3]. A second approach is the application of load optimized design methods. By adapting the shape of different body-in-white components to the expected loads, savings of material can be made, reducing the overall mass of the body-in-white [4]. However, the resulting part geometries are usually not accessible to standard roll forming where only constant profile cross sections along the longitudinal axis of the profile can be manufactured [5].
Fig. 1. Breakdown of mass of passenger vehicle by components (approximate). [6]
The target of 3D Roll Forming is to widen the realm of possibilities in roll forming to include profiles with variable cross sections and so fulfill the demands of the automotive industry for more complex geometries. Moreover, traditional roll-forming lines make current profile production techniques inefficient for small-batch production, which is typical in the manufacture of high-value products (e.g. sports cars, SUVs or aircraft). 3D Roll Forming aims to open up new markets by enabling small production runs and rapid prototyping of profiles in a cost effective way [7]. The latest advances in 3D Roll Forming are only possible due to a well-established virtual process design chain, where a CAD system is used for the initial process design and simulations are generated for the process validation and the generation of optimized tool motion paths [7]. Any defects that would otherwise plague the completed system are also detected in an early design phase. The COPRA® system provides such an integrated process design approach, and can be seen as a digital roll forming mill, where different strategies can be tried out in a very short time and without any manufacturing costs [8]. Furthermore, the integration of various types of sensors for real time monitoring of the 3D Roll Forming process facilitates quick reactions to manufacturing problems due to the inherent flexibility of the process. This is also the first step towards the automatic correction of manufacturing defects through the use of machine learning algorithms and big data analysis [9]. Beyond the pure digitalization of the control units of production machines, great expectations are placed on the collection and analysis of data - a collection of topics often referred to as smart factories or industry 4.0. Roll forming is often perceived as somewhat trailing behind current trends in this area. This may be related to the comparative longevity of the roll forming machinery and the associated longer planning cycles for investments in production facilities. However, data M sees the potential for process improvements of these techniques, and even though the introduction of industry 4.0 in roll forming is a complex topic, a program to develop the necessary strategies and tools has been started. 2. Efficient planning tools In traditional roll forming of geometries with constant cross sections proven design-process-chains are being used. Starting point for the process design is a CAD system. The CAD model of the desired profile is the basis for the development of forming tools and a suitable forming machine, respectively.
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In the first steps, a so-called flower pattern is developed, defining the subsequent incremental bending steps from a flat strip to the final profile. The cross sections in each bending step are the basis for the following design of the required roll tooling. Tooling and machine parameters (distance of forming stands, distance of roll axes, stiffness of forming stands) are, in the next step, essentially the input to build a finite element model. The effort to build the finite element model is reduced to a minimum as highly specialized pre-processors are doing this job automatically directly from the CAD system. The simulation using special FEA-solvers allows for a quick validation of the modelled forming process. The tool engineers can thus easily investigate and benchmark different variants of forming strategies. Due to the fact that the (normally) time consuming and error-prone FEA modelling job has been eliminated, product development is accelerated substantially and product quality becomes predictable. The roll forming tooling can be optimized in iteration loops, considering factors such as product quality, the quality of the forming process itself (dimensional stability, surface finish, process stability…) as well as cost for tooling and cost for the whole production process (roll tool dimensions, number of forming steps required…). data M’s software package COPRA® is already providing a highly efficient workflow in the design and simulation process for classic roll forming.
Fig. 2. (a) COPRA® - Tool design and simulation software; (b) and (c) example of results of 3D roll forming simulation.
2.1. 3D roll forming Compared to “classic roll forming” the so-called “3D roll forming” widens the range of application by profile shapes having a variable cross section over its longitudinal axis. This necessitates also further development of the proven planning workflow and requires new tooling concepts. A single flower pattern for all subsequent forming steps is no longer sufficient to describe a 3D roll forming process. Instead it is necessary to develop individual flower patterns for every single cross sectional geometry occurring in the 3D profile have to be developed. This directly leads to the question of the correct sheet metal precut for profiles with variable cross sections. The various profile flower patterns take us to a first draft of the required pre-cut. The real size of sheet metal pre-cut has to be determined by some finite element simulation. This is because the forming strategy used has a decisive influence on the strip edges and thus on the contour of the incoming sheet strip.
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Subsequently multiple challenges are to follow regarding the roll forming line and its roll tooling concept. For instance - every single forming roll has to fit into different profile cross sections. The rolls are moving along the variably changing profile geometry in order to ensure a continuous forming. For a width-variable profile this means for instance a combination of rotational and translational movements within the profile’s flanges. This may lead to collisions between roll and profile or even between the rolls itself, if the tooling was not optimized in advance. Other challenges to be taken into account are the kinematic and dynamic behavior of the forming machine.
Fig. 3. Flower pattern of load-optimized profile.
Depending on the shape of the load matching profile to be produced the work space of all the roll forming stations should be determined. The maximum roll forming speed is limited by the dynamic behavior of the forming stand’s actuators. All these calculations are, for example, incorporated in the evaluation of economic efficiency and the dimensioning of electric drives or mechanical parts. 2.2. Process planning tools for 3D roll forming The process planning tools for 3D roll forming are based on the already established design-process-chain of COPRA®. The software module COPRA® RF assists in the design of profile flowers and forming rolls – also for load matching 3D profiles. A software interface offers the possibility to export the complete roll tooling to the 3D CAD system Autodesk® Inventor in order to conduct collision checks or fit into an existing machine design. The central point in the virtual process development is at this stage the finite element simulation software COPRA® FEA RF. This high-end simulation uses 3D hex-elements along with an implicit solver; which due to contact, material models and friction becomes highly non-linear. This software package has been extended (within the development of 3D roll forming) by adding kinematic modules allowing the 3D roll tool movement. The roll tool curves (trajectories) are derived from the 3D part geometry and transferred to the simulation program – for each single forming tool. The results of these simulations are providing detailed information about the feasibility of a 3D profile, for instance: • • • •
Expected profile quality with regard to geometrical issues (Flatness, warping, bending angles of flanges in transitional areas, deviations etc.) Is it advisable to modify the design of the required profile to better suit the roll form process? Often related to the transition zones between different cross sectional areas. Range of expected forming forces, driving torques or rotational speeds. Does this process fit into an already existing 3D roll forming line (with regard to roll diameter, distance of axes, forming forces, working space of flexible forming stands) or is it required to design a new mill?
For the conception of a new 3D roll forming mill the same planning instruments are used. However, due to the fact that the forming tools in a 3D RF mill are being moved through complex parallel kinematics, some classic engineering instruments cannot be applied immediately. Depending on the roll tool position in 3D space, loads on the actuators can change drastically. The feedback of forming forces on the behavior of the machine’s structure is thus of great importance.
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The solution for this challenge is the co-simulation between COPRA® FEA RF (a nonlinear FE software) and a multibody dynamics simulation software like MSC Adams®. This allows the engineer to study the dynamics of moving parts and loads and how loads and forces are distributed throughout the complex movement of rolling tools, resulting in drastic improvement of the quality of the machine design. At the same time, for the dimensioning of the actuators, data M’s engineers use control technology which has been developed specifically for roll forming lines: COPRA® Adaptive Motion Control. This software package is in its “virtual mode” assisting in the planning and dimensioning process for roll forming of 3D load matching profiles. In a first stage the kinematic devices of each forming station are parametrized in the control. The engineer inputs the trajectories of each station and starts some simulation run on the control. The control helps (for instance for a given roll forming speed) to determine the maximum axial or revolution speed of the motor drives. During the virtual forming process, the control records the changes of velocity in each forming stand. As the dynamic of each actuator and their maximum speed are limited, this method allows (considering all controlled axes) the determination of the maximum possible speed of the whole forming process. In other words: what will be the maximum roll forming speed. Based on this principle the motor drives of such a 3D roll forming line are being optimized which in turn leads to the final mechanical dimension of the machine and the electrical cabinets as well. Clearly these thoughts are taken into consideration in the commercial viability of the whole system.
Fig. 4. User interface of COPRA® Adaptive Motion Control.
3. Load optimized parts for commercial vehicles (trucks) Similarly to car manufacturers, producers of commercial vehicles also have an interest in light weight- and especially in load-optimized designs of their chassis frames. There is also interest in an increased number of possible variants in consequence of requirements for transportation, driving systems, special purpose vehicle bodies. Recently the author’s company has presented a 3D roll forming line for the production of chassis long members for trucks [9]. This mill allows for the production of a family of more than 50 long members with different profile geometries using only a single tool set. The high level of digitization reduces set-up time to almost zero. Simply the recipe- or program change, operated by the MES (Manufacturing Execution System) or locally by the operator, is required. The presented machine concept is highly flexible. Therefore the smallest or largest of batches can be produced at the minimum cost and utmost energy efficiency. Due to the use of the most advanced control technology along with specially developed parallel kinematic mechanics both geometrical and/or material changes can be compensated quickly. Another advantage of this method is the simple compensation of spring back by adaptation of only a few forming rolls, therefore allowing high tensile steels to be roll formed reliably. The open and flexible control concept with
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soft- and hardware-interfaces allows for an easy integration in existing production lines. Data transfer to or from ERP- or MES systems can be realized using OPC UA.
Fig. 5. (a) 3D roll forming line for truck beams developed by data M SMS with 96 simultaneously controlled axes; (b) example of chassis frame with load optimized long members.
Process- and machine data can be stored in local or cloud-based data bases in real-time. Thus allowing (based on this data) the future possibility to predict machine maintenance and availability periods as well as process robustness and product quality. 4. The 3D RollformingCenter® Traditional Roll Forming is usually not suitable for small lot sizes. However, these are common in the production of high-class products like sports cars, SUVs or aircrafts, meaning roll forming has been “locked out” from complex geometries with variable cross sections being used in the automotive industry. This is the reason for presenting a new machine- and forming concept. Using advanced robotics, roll forming tools can be positioned freely in space. The combination of modern control technology and simulation technology has led to digitization of the production process allowing for the production of smallest lot sizes of load-optimized and also classic profiles. Alternatively this concept can be used for rapid prototyping in roll forming as well as process development and optimization. There is also room for applications in material research – especially with regard to hybrid/ multi materials or high tensile materials. Furthermore, one of the positive advantages with this machine concept, are very low tooling costs, compared to other forming methods. 4.1. Description of forming method and machine
Fig. 6. A flat raw sheet is placed into die taking shape of profile’s web. Roll forming tools move along die (trajectories).
Like in an oversized bench vice with a prefabricated shape, the flat raw sheet strip is placed in a die, where the sheet already takes the shape of the profile’s web. The roll forming tools themselves then move along trajectories in order to form the profile’s flanges step by step around the top die – until the final profile shape is reached.
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4.2. Concept of machine The 3D RollformingCenter® could be likened to a roll form simulator – consisting of a single pair of forming stands. The sheet, clamped in a die and mounted on a linear slide, passes the roll forming stands in alternating direction. The roll forming stands (one on each side) are mounted on a robot which aligns the forming rolls into the correct forming position. Given a straight profile with constant cross section, the robot would not move during one forming process – it would just keep the rolls in their position. Just before the second forming cycle the rolls will be brought into their new bending position. Several bending operations can be done with one and the same rolls. The robots have a tool changing system for fast and precise tool changes during production. The 3D RollformingCenter® consists of a machine bed with a linear slide, hydraulically holding the driven upper and lower dies. Perpendicular to this slide are a pair of hexapod robots (left and right) each with moveable platforms holding the roll forming stands. The control system synchronizes the movements of the linear slide with the hexapods.
Fig. 7. 3D Roll Forming Center® with hexapod robots and roll tooling.
Forming a 3D Profile, the robots are changing their position while the linear slide is moving from left to right (or vice versa). The hexapod mechanism is able to follow every combination of translational or rotatory movements. The greatest advantage of this machine is its high flexibility due to the digitization of the roll forming tooling. The system can react instantly to changes in material behavior, for instance, by programming additional intermediate forming steps. By using this procedure, the forming of a width-variable profile was successfully optimized – without the need of changing the rolls or making new ones, instead just by reprogramming the robot’s bending angle. Several trials to form load matching parts on the 3D RollformingCenter® have been successfully carried out investigating two categories of profiles: firstly being variable in width and secondly with variation in height.
Fig. 8. Different automotive parts already produced on 3D RollformingCenter.
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4.3. Concept of industrial line With the 3D RollformingCenter® it is now possible to investigate and validate new concepts for industrial lines at a very early development stage. Profile quality, feasibility as well as prototype parts can be investigated in the forefront of any subsequent planning steps, both cost efficient and quickly. Concerning tooling, only the holding die (manufactured from simple material) and the usually very simple and small forming rolls have to be manufactured. At the author’s company a concept for high volume industrial production has been developed. In a first step, the part has been formed on the 3D RollformingCenter® and the whole forming process optimized. Additionally, by analyzing the profiles trajectories, the number of forming tools and the number of required degrees of freedom (controlled axis) could be reduced significantly in any future, proposed or planned 3D RF machine. 5. Outlook The first 3D RollformingCenter® has been shipped to a renowned Australian material research institute. The target of their investigation is new materials such as high tensile steels and their forming behavior. The concept of this prototyping machine is also suitable for the cost effective and flexible production, of small batches of profiles. Due to this highest flexible machine concept, both conventional as well as 3D geometries can be produced in a “rapid prototyping” manner. Further areas of interest are the development of innovative sensor technology for roll forming. At the author’s company a prototype of a new 3D laser triangulation sensor was developed. This is able to scan the full profile length in the machine. Along with respective control technology and integrated sensors the subject “big data” for roll forming 4.0 can get pushed forward. The author’s company is looking for industrial partners introducing this promising new technology. References [1] G. Fontaras, V. Franco, P. Dilara, G. Martini, U. Manfredi, Development and review of Euro 5 passenger car emission factors based on experimental results over various driving cycles, Science of the total environment, 468 (2014) 1034–1042. [2] L. Eckstein, R. Göbbelsist, M. Goede, T. Laue, R. Wohlecker, Analyse sekundärer gewichtseinsparpotenziale in kraftfahrzeugen, ATZ Automobiltechnische Zeitschrift, 113 (2011) 68–76. [3] H.E. Friedrich, D. Hülsebusch, Elektrofahrzeugkonzepte und leichtbau:anforderungen für neue werkstoffe?, Lightweight Design, 2 (2009) 18–24. [4] A. Sedlmaier, R. Hennig, A. Abee, Fabrication of load optimized truck members with variable cross sections by flexible roll forming, Proceedings International Conference on Steels in Cars and Trucks, Salzburg, (2011). [5] B. Abeyrathna, A. Abvabi, B. Rolfe, R. Taube, M. Weiss, Numerical analysis of the flexible roll forming of an automotive component from high strength steel, IOP Conference Series: Materials Science and Engineering, 159 (2016) 012005. [6] A. Mayyas, A. Qattawi, A.R. Mayyas, M.A. Omar, Life cycle assessment-based selection for a sustainable lightweight body-in-white design Energy, 39 (2012) 412–25. [7] A. Sedlmaier, T. Dietl, Recent advances in the industrial application of flexible (3D) roll forming for automotive parts by the use of modern CAE tools, Proceedings IDDRG 2015 Conference, Shanghai, (2015). [8] A. Abee, A. Sedlmaier, C. Stephenson, Development of new 3D roll forming applications by means of numerical analysis as a part of a quality control methodology, CBM Metal Matters, 18 (2010) 21–23. [9] T. Dietl, A. Sedlmaier, T. Schneider, Multiachs steuerungstechnik im einsatz für die herstellung von walzprofilen (mit 3D Konturen), Proceedings 36. EFB Kolloquium, Fellbach, (2016). [10] https://youtu.be/-ExYY8LfU9A [11] https://youtu.be/7I1EMPflBAw