Simulation and Optimization of Metal Forming Processes

NSMSimulation and Optimization of Metal Forming Processes New Applications and Challenges 19. Umformtechnisches Kolloquium Hannover: 27/28 Februar 2008 Manas Shirgaokar, Graduate Research Associate ([email protected]) Ajay Yadav, Graduate Research Associate ([email protected]) Dr. Taylan Altan, Professor & Director ([email protected]) Engineering Research Center for Net Shape Manufacturing, ERC/NSM The Ohio State University, Columbus, Ohio http://www.ercnsm.org © Copyright Engineering Research Center for Net Shape Manufacturing, 2008 ERC Precision Forging Group 1 Outline • Need for Process Simulation in Metal Forming. • Requirements for Process Simulation. – Material Properties. – Interface Friction Conditions. NSM ERC • Selected Process Modeling Case Studies. – Precision Cold, Warm and Hot Forging. – Stamping. • Summary and Concluding Remarks. © Copyright Engineering Research Center for Net Shape Manufacturing, 2008 Precision Forging Group 2 flash. Training of personnel/access to advanced technology. Reduce defects and scrap rate. etc. Increase utilization rate of forming equipment. Efficient information management. Precision Forging Group 3 © Copyright Engineering Research Center for Net Shape Manufacturing. Increase automation and decrease labor content.Improvement of Profitability NSM ERC Steps to increase profitability in global competition: – – – – – – – – Increase material utilization (reduction of scrap.). Increase die service life. Process optimization by use of computer aided engineering (CAE) tools. 2008 . internal pressure vs.Process Simulation using CAE NSM ERC Main Goal: Reduce part development time and cost. – Die material selection and process design for improved die life in warm and hot forging. Specific Goals: – Optimization of blank-holder force and blank geometry in stamping. and increase quality and productivity. 2008 Precision Forging Group 4 . © Copyright Engineering Research Center for Net Shape Manufacturing. – Prediction of internal defects and part quality in cold forging. – Optimization of hydroforming. axial feed in tube – Preform and die design optimization for improved material yield in hot forging. (Cho et al. 2003) © Copyright Engineering Research Center for Net Shape Manufacturing. • Upset load versus stroke and shape of the billet at the end of forming are used in FE simulation-based inverse analysis technique to estimate the flow stress that compensates for friction.8 mm.65mm. 5. Maximum radius Maximum radius 4. 4.8mm. 2008 Precision Forging Group 5 .65 mm. CL CL 5.Process Modeling Requirements ERC NSM -Material PropertiesForging: Cylinder Compression Test • Barreling occurs at the center plane of the specimen due to the friction at the die-specimen interface. and – The maximum effective strain achievable in the tensile test is relatively small because of local necking.Process Modeling Requirements ERC NSM -Material PropertiesStamping and Sheet Hydroforming : Viscous Pressure Bulge (VPB) Test •Material properties obtained from tensile test are not adequate for process simulation. – Stress conditions in stamping/ sheet hydroforming are often biaxial compared to uniaxial in the tensile test. 2008 Precision Forging Group 6 . 2004) © Copyright Engineering Research Center for Net Shape Manufacturing. Fc td hd t0 dc Fc Rd p Rc (Gutscher et al. 4 0. h © Copyright Engineering Research Center for Net Shape Manufacturing.2 Precision Forging Group Penetration depth(mm) (Cho et al. Loading 60000 50000 Punch force(N) Experiment FEM Simulation A 40000 30000 20000 10000 0 Ball indenter Workpiece Indentation depth.8 1 1.6 0. 2004) 7 . 2008 0 0. • The load versus stroke is measured continuously and used as an input to an FE simulation-based inverse analysis technique to estimate the flowP-h curve comparison stress.Process Modeling Requirements ERC NSM -Material PropertiesSurface Properties: Indentation Test • The indentation (micro-hardness) test is used to estimate local flow stress of the material near the surface.2 0. Lubricants are evaluated and ranked on the basis of the cup height ratio.NSM Forging: Ring Compression Test (RCT) and Double Cup Extrusion Test (DCET) •The DCET is used to evaluate lubricants in processes that involve high contact pressures and surface expansion. 2008 Precision Forging Group 8 . •The friction factor in both cases is estimated using calibration curves developed through FE analysis. Lubricants are evaluated and ranked on the basis of the change in ring inner diameter for different height reductions. © Copyright Engineering Research Center for Net Shape Manufacturing. •The RCT is mainly used to test lubricants in cold heading and warm/hot forging due to its simplicity.Process Modeling Requirements ERC -Interface Friction Conditions in Forging. 2008 b) Ring Compression Test. © Copyright Engineering Research Center for Net Shape Manufacturing.Process Modeling Requirements ERC -Interface Friction Conditions in Forging.NSM Upper Pu Upper Punch Billet H1 H2 Lower Lower Punch a) Double Cup Extrusion Test. 9 Precision Forging Group . Also. both in the flange and in the punch. The largest blank holder force that can be used to draw the cup without failure indicates the performance of the lubricant. a large punch force indicates bad performance of the lubricant. © Copyright Engineering Research Center for Net Shape Manufacturing. • The higher is the blank holder force. • Circular cups are drawn from a blank of fixed draw ratio but with different blank holder force until they fracture.NSM Stamping: Deep Drawing Test • This test emulates the interface condition that exists in production. 2008 Precision Forging Group 10 .Process Modeling Requirements ERC -Interface Friction Conditions in Stamping. the better is the performance of the lubricant in the test. © Copyright Engineering Research Center for Net Shape Manufacturing.NSM Stamping: Deep Drawing Test • Experimental evaluation of lubricant performance.Process Modeling Requirements ERC -Interface Friction Conditions in Stamping. 2008 Precision Forging Group (Kim et al. 2006) 11 . 2004) 12 . Tool Inner race Spindle Initial stage Final stage © Copyright Engineering Research Center for Net Shape Manufacturing. tool axis angle. etc. deformed geometry of the spindle. on the residual stress in the bearing inner race of the assembly.Process Modeling Applications -Incremental FormingOrbital Forming of Wheel Bearing Assembly: NSM ERC Determine the influence of various process parameters such as axial feed. 2008 Precision Forging Group (Cho et al. and the axial load that the assembly can withstand.. Initial blank Formed part (Blank thickness = 0. 2008 Precision Forging Group (Palaniswamy et al.01 mm) © Copyright Engineering Research Center for Net Shape Manufacturing. Final blade thickness = 0.1 mm. • The designed tool geometry was successfully used in production to coin this part. 2002) 13 . the flash thickness was reduced such that grinding of flash was replaced by electro-chemical machining (ECM).Process Modeling Applications -Microforming of Medical DevicesMicroforming of a Surgical Blade: NSM ERC • Using FEA with die stress analysis. -Material Yield Improvement in Hot Forging. forging temperatures as well as flash dimensions . 2008 Precision Forging Group 14 . Process Modeling Applications ERC © Copyright Engineering Research Center for Net Shape Manufacturing.NSM Hot Forging of Suspension Components: • A study was conducted for a tier one aluminum forging supplier to optimize the preform and die (blocker and finisher) designs. -Material Yield Improvement in Hot Forging. with an additional 3-4 % improvement through blocker die design. 2008 Precision Forging Group Final Forging with Reduced Flash 15 .NSM Material yield was increased by ≈15% through preform optimization. Process Modeling Applications ERC Original Finisher Forging © Copyright Engineering Research Center for Net Shape Manufacturing. © Copyright Engineering Research Center for Net Shape Manufacturing.Process Modeling Applications -Improvement of Die Life in ForgingDie Wear Study (Forging Industry Association): NSM ERC • Main Goal: Prediction and improvement of die life in warm and hot forging processes through combination of FEA and shop-floor trials under production conditions. – Selection and comparison of die materials through FEA. – Design of shrink-fitted dies with ceramic and carbide inserts accounting for thermal expansion during preheating and forging. – Preform and die design for reduction of die-workpiece contact time and relative sliding. • Specific Goals: – Identification of interface conditions at start-up and steady-state. 2008 Precision Forging Group 16 . tb 0 1268 1068 Time 0.2 t1 0.6 0.Process Modeling Applications -Improvement of Die Life in ForgingForging Process Simulation Production Cycle-time Data: with 1000 TDC Forging BDC Dwell Tmax 900 NSM TDC Cooling ERC •Die chill time i.4 t2 300 To. the lubrication spray time and the dwell time until the next billet is placed on the die. Temperature (F) 868 668 468 268 68 0 50 100 150 Steady-state Time (sec) 200 250 300 350 © Copyright Engineering Research Center for Net Shape Manufacturing. the time spent by the billet on the bottom die until contact with the top die. the time from start of deformation until bottom dead center (BDC).e.e. •Dwell time i.8 tc te1 tf 1. Die Temperature (F) 800 700 600 500 Tmin 400 Die chill Start-up 0. •Deformation or forging time i.e. •Cooling time i. 2008 Precision Forging Group 17 . the time until part removal/ejection.e. USA). 2008 Precision Forging Group 18 . • Effect of die material properties on thermal fatigue performance was investigated in order to screen alternative die materials. USA). • Loss of compressive stress in a shrink-fit die was determined through simulation of die heating and multiple-cycle forging (American Axle. USA).Process Modeling Applications -Improvement of Die Life in Forging- NSM ERC • Scrap rates were reduced by 50% in a hot forging process through improved preform design and die material selection developed by FEA of the forging process (Impact Forge. © Copyright Engineering Research Center for Net Shape Manufacturing. • The application of matrix-high speed steels is being explored through production trials (Hirschvogel. 2008 Precision Forging Group (Palaniswamy et al.Process Modeling Applications -Blank Design in StampingDetermination of Slot Location and Shape: NSM ERC • FEA using PAMSTAMP-2000™ was used to determine the optimal slot shape and location in the initial blank for a sample part (automatic transmission component). 2002) 19 . © Copyright Engineering Research Center for Net Shape Manufacturing. • This helped to eliminate an expensive post-stamping laser cutting operation. t=0.0 mm. BH210.8 mm). an optimization technique was developed coupled with FE codes to estimate the blank holder force that is variable in space and constant in stroke. 2002) 20 . • The developed software was used to predict the blank holder force required to form a full size automotive panel (Lift-gate – inner) from three different materials (aluminum alloy A6111-T4. 2008 Precision Forging Group (Palaniswamy et al. t=1. © Copyright Engineering Research Center for Net Shape Manufacturing.Process Modeling Applications -Blank-holder Force ControlProgramming a Multipoint Cushion System: NSM ERC • As part of a USCAR project.8 mm and DP500 t=0. 2008 Precision Forging Group 21 .Process Modeling Applications -Blank-holder Force Control- NSM ERC © Copyright Engineering Research Center for Net Shape Manufacturing. Process Modeling Applications -Progressive Die Design- NSM ERC A process sequence was designed for the part shown. The existing design was improved through FE simulation to reduce the potential for failure in the formed part (excessive thinning and wrinkling). 2008 Precision Forging Group 22 . © Copyright Engineering Research Center for Net Shape Manufacturing. to investigate deep drawing of a magnesium alloy.Process Modeling Applications -Warm Forming of Lightweight Alloys- NSM ERC Warm sheet forming of magnesium and aluminum alloys • A study was conducted. an aluminum alloy and austenitic stainless steel at elevated temperature.0 can be obtained at 300° C with maximum ram velocities of 2 mm/sec and 5 mm/sec for AZ31B and AL5754-O sheet material. respectively. 2008 Precision Forging Group 23 . • Maximum draw ratio of 3. © Copyright Engineering Research Center for Net Shape Manufacturing. in co-operation with AidaAmerica. • The sheet was heated in the tooling and then formed at different speeds using a servo motor driven press that allows infinite degrees of freedom to control the ram motion and speed. 6 2.Process Modeling Applications -Warm Forming of Lightweight Alloys- NSM ERC Magnesium : AZ31B 250 C 275 C 300 C 250 C Aluminum: 5754-O 275 C 300 C 250 50 forming velocity [mm/s] forming velocity [mm/s] 2.2 Lim iting Draw Ratio (LDR) Lim iting Draw Ratio (LDR) © Copyright Engineering Research Center for Net Shape Manufacturing.4 2.8 2.1 3.9 3 3.5 2.2 200 1 50 1 00 50 0 40 30 20 1 0 0 2.8 2.9 3 3.1 3.7 2.5 2. 2008 Precision Forging Group 24 .7 2.4 2.6 2. Summary NSM ERC • Process modeling through FE simulation is an essential tool in modern metal forming to reduce the development cost and time. 2008 Precision Forging Group 25 . • Continuous development of FE software for metal forming has increased its scope to cover a large range of metal forming processes including warm sheet forming and metal cutting. © Copyright Engineering Research Center for Net Shape Manufacturing. • In this paper an overview is given on the application of FE simulation for industrially relevant practical problems. References • NSM ERC H. “3D finite element analysis of orbital forming and inverse analysis for determination of flow stress of the workpiece”. 2004.C.Palaniswamy. G. J. Columbus. G. Sung. G. 2002. accepted for publication in the International Journal for Machine Tools and Manufacture. “Finite element based inverse analysis for determination of flow stress for determination of flow stress data and friction”. Journal of Materials Processing Technology Vol. T. Sivakumar.Ngaile. T. 2006. H. pp 1502 –1507. Columbus. H. G. H. G.Cho. Altan. N.Ngaile.Altan. R.Altan. T. Annals of CIRP. “Determination of flow stress for sheet metal forming using the viscous pressure bulge (VPB) test”. Kim. Wu. Vol 52. NUMIFORM 2004. Ngaile. Ohio. T.Altan. H. ERC Report no: S/ERC/NSM –02-16. H. Materials Processing and Design: Modeling.Ngaile. The Ohio State University. “Simultaneous determination of flow stress and interface friction by finite element based inverse analysis technique”. Cho. The Ohio State University.Kim. Altan. Precision Forging Group • • • • • © Copyright Engineering Research Center for Net Shape Manufacturing.Cho. T. 146. 2008 26 . pp 1-7.Altan. 2003. Gutscher. 2004. “Evaluation of stamping lubricants using deep drawing test”. 2004.ERC report no: F/ERC/NSM-04-R-20. “Coining of surgical slit knife”. pp 221-224. Ohio. Simulation and Application. T. Journal of Manufacturing Science and Engineering). ERC/NSM Report no. Vol 55/1. 2006.Palaniswamy. Ohio. Spampinato. The Ohio State University. Altan. Braedel.Jain. M. T. H. “An Experimental Study on Non-Isothermal Deep Drawing Process Using Aluminum and Magnesium Alloys”. A. 2008 Precision Forging Group 27 .” Optimal programming of multipoint cushion systems in sheet metal forming”.Altan. Annals of CIRP. Columbus. Thandapani. Altan. 2007. T. • • © Copyright Engineering Research Center for Net Shape Manufacturing. 2002.References • NSM ERC H. pp 249-254. ERC/NSM – 02 –102. T. N. S. “Design of optimal slot shape and blank shape using finite element analysis”. Kaya. Palaniswamy. G. (in review –.