Presentation on theme: "Center for Precision Forming"— Presentation transcript:
1Center for Precision Forming (www.cpforming.org)Taylan Altan, Director (A short ReviewJuly, 2011
2IntroductionThe Ohio State University (OSU) and have established the Industry/University Cooperative Research Center (I/UCRC) on Precision Forming (CPF) focusing on research needs of metal forming industry.Funding is provided by National Science Foundation (NSF) and member companies.CPF (www.cpforming.org) benefits from research conducted at Engineering Research Center for Net Shape Manufacturing (ERC/NSM –
3ObjectivesImprove existing metal forming processes/products and develop new innovative processes, tooling and equipment.Conduct projects in close collaboration with industry and transfer the results to the member companies.Train and educate engineers in the fundamentals and practice of metal forming science and technology.
4Current Members Boeing Cincinnati Inc Dienamic Tooling Systems ESI North AmericaEWIHondaHyundaiInterlaken Technology Corp.POSCO (Korea)IM SteelScientific Forming Technologies (SFTC) Corp.IMRA AmericaMetalsaTyco
6R&D in Sheet Metal Forming at CPF CPF Elevated temperature stamping and hydroforming (Mg, Al and alloys)CPF Control of springback and dimensional tolerances in forming AHSS partsCPF 2.1 – Determination of room temperature material properties (flow stress, formability, anisotropy) of sheet materials under biaxial conditionsCPF 2.3 – Investigation tribological (friction/lubrication/wear) conditions in forming uncoated and galvanized AHSSCPF 2.5 – Evaluation of lubricants for improving stamping qualityCPF 4.1 – Practical use of multi-point control (MPC) die cushion technology in production of stamped parts
7R&D in Sheet Metal Forming at CPF CPF 4.2 – Tube hydroformingCPF 5.1 – Evaluation of bendability of AHSSCPF 5.2 – Prediction and elimination of edge cracking of AHSS in stretch flangingCPF 5.3 – Blanking and shearing of sheet metalCPF 5.5 – Hot stamping of boron steelsCPF 5.6 – Applications of servo drive presses in stamping
8Manan Shah Jose L. Gonzalez-Mendez Eren Billur CPF Elevated Temperature Stamping and Hydroforming (Mg, Al And Alloys)Manan ShahJose L. Gonzalez-MendezEren Billur
9Al, Mg, Ti & SS (Cup Diameter: 40 mm) (in cooperation with AIDA) Warm Forming ofAl, Mg, Ti & SS (Cup Diameter: 40 mm)(in cooperation with AIDA)AZ31B-OAA5754-OT(°C)LDRRT2.12502.53002.9T(°C)LDRRT-2752.63.2Velocity : mm/sec
10(in cooperation with AIDA) Warm Forming ofSS 304 (Cup Diameter: 40 mm)(in cooperation with AIDA)
14Nimet Kardes-Sever Yurdaer Demiralp Dr. Changhyok Choi CPF Control of Springback and Dimensional Tolerances in Forming AHSS PartsNimet Kardes-SeverYurdaer DemiralpDr. Changhyok Choi
15Load-Unload Tensile Test (in cooperation with EWI) SpringbackLoad-Unload Tensile Test(in cooperation with EWI)
16(in cooperation with EWI and IVF) Springback in S-Die Test (FEA and Experiments)(in cooperation with EWI and IVF)Material: DP 780, DP 600thickness: 1 mm, 0.75 mmU-flanging without stretchingU-bending without stretchingU-flanging with stretchingU-bending with stretchingS-shape forming with – without stretching
17(in cooperation with EWI and IVF) Springback in S-Die Test (FEA and Experiments)(in cooperation with EWI and IVF)U-flanging testU-bending testSchematic of S-shape punchU-bending sample on S-shape punchU-flanging sample on S-shape punchS-shape bending sample on S-shape punch
18CMM measurements of S-Die Test Samples Calculation of springback for S-Die Test samples:Bending angle under load was measured by camera when possible. When the tool is closed it is not possible to take pictures. Therefore, it was assumed that the specimen geometry under load is determined by tool geometry.Bending angle after unloading was measured by protractor and camera when possible and Coordinate Measurement Machine (CMM).For complex samples, sections before and after springback were compared.Schematic of CMM measurements on a sample
19Eren Billur Yurdaer Demiralp Nimet Kardes-Sever Ji You Yoon CPF Determination of Room Temperature Material Properties of Sheet Materials Under Biaxial ConditionsEren BillurYurdaer DemiralpNimet Kardes-SeverJi You Yoon
20Sheet Material Properties Viscous Pressure Bulge (VPB) Test (in cooperation with many companies)After FormingLaserTest SampleViscous MediumStationary PunchPressure TransducerBefore FormingDownward motion clamps the sheetContinued downward motion forms the bulged sheet
21Sheet Material Properties Tensile Test vs. VPB Test Due to necking, flow stress data from tensile test is limited to low strains.Bulge test is useful to determine flow stress curve for metal forming applications and FE simulations.Bulge test is useful to determine the quality (formability) of sheet materials.
22Determination of Sheet Formability Using VPB TestGraph shows dome height comparison for SS 304 sheet material from eight different batches/coils [10 samples per batch].Highest formability G , Most consistent FLower formability and inconsistent H
23Materials Tested with VPB Test at CPF (data available to CPF members)SteelsSt 14DP 780-CRSt 1403DP 780-HYAISI 1018Bare DP 980 Y-type XAKDQBare DP 780 T-Si type1050GA DP 780 T- AI TypeDR 120GA DP 780 Y-type UDDSGA DP 780 Y-type VBH 210 DQS-270F GA-Phosphate coatedHSS DQS-270D GA-Phosphate coatedDP500DP 590DP 600DP 780TRIP 780DP 980Aluminum and Magnesium AlloysAA 6111AA 5754-OX626 -T4PAZ31BAZ31B-OStainless SteelsSS 201SS 301SS 304SS 409SS 410 (AMS 5504)SS 444LDX 2101
24Eren Billur Ryan Patton CPF Investigation Tribological (Friction/Lubrication/Wear) Conditions in Forming Uncoated and Galvanized AHSSEren BillurRyan Patton
25Evaluation of Die Materials/Coatings for Galling and Die Wear Using TheStrip Drawing and Ironing Test (SDT/SIT)(in cooperation with HONDA )Strip Drawing TestGalling observed on a die insertStrip Ironing TestHigher contact pressure accelerates the tool wear and galling, in stamping AHSS.Various die materials and coatings are evaluated by SDT and SIT.
26CPF 2.5 - Evaluation of Lubricants for Improving Stamping Quality Soumya SubramonianNimet Kardes-SeverYurdaer Demiralp
27Evaluation of Lubricants Using The Cup Drawing Test (CDT) (in cooperation with HONDA and several lubricant companies)Performance evaluation criteria (cups drawn to same depth):Higher the Blank Holder Force (BHF) that can be applied without fracture in the drawn cup, better the lubrication conditionSmaller the flange perimeter, better the lubrication condition (lower coefficient of friction)
28Evaluation of Lubricants Using The Cup Drawing Test (CDT) – Results (in cooperation with HONDA and several lubricant companies)Mill oil+
29CPF Practical Use of Multi-point Control (MPC) Die Cushion Technology in Production of Stamped PartsDr. Taylan Altan
30Case studies in process simulation Multi-point Control systems (MPC)Hydraulic systemsIFU flexible Blank holder / Binder hydraulic control unitErie binder unit (hydraulic system) with liftgate tooling inside press(Source: IFU, Stuttgart)(Source: USCAR)
31Application of MPC die cushion technology in stamping Case studies in process simulationMulti-point Control systems (MPC)Application of MPC die cushion technology in stampingSample cushion pin configuration (hydraulic MPC unit) for drawing stainless steel double sink.(Source: Dieffenbacher, Germany)MPC is routinely used in deep drawing of stainless steel sinks
32Case studies in process simulation Multi-point Control systems (MPC)Previous work at CPF in Blank Holder/Binder Force (BHF) determinationCPF in cooperation with USCAR consortium developed software to program MPC die cushion system in stamping.Methodology for BHF determination (Numerical optimization techniques coupled with FEA)Inputs requiredBHF at each cushion pin as function of punch strokeSoftware developed at CPF for BHF determinationQuality control parameters (wrinkling, thinning)No. of cushion cylinders (n)Tool geometry (CAD)Material propertiesProcess conditionsFEA Software(PAM-STAMP, LS-DYNA)
33Multi-point Control systems (MPC) Case studies in process simulationMulti-point Control systems (MPC)Use of Multi-point Control (MPC) die-cushion systems helps to control metal flow.Each cushion pin is individually controlled by a cylinder (hydraulic/ nitrogen gas /servo control).Location of cushion pins/ cylinders in the dieMPC can be used to accommodate variations in sheet properties & assist in forming AHSS.
34Multi-point Control systems (MPC) Case studies in process simulationMulti-point Control systems (MPC)FE modelDieEstimation of BHF varying in each cushion pin & constant in stroke, using FE simulation coupled with numerical optimization, developed at CPF (OSU).Geometry : Lift gate innerMaterial : Aluminum alloy, AA6111-T4Initial sheet thickness : 1 mmSheetBeadsSegmented blank holder[Source: USCAR/OSU]Inner BinderCushion PinOuter BinderPunch
35Multi-point Control systems (MPC) Case studies in process simulationMulti-point Control systems (MPC)BHF predicted by FE simulation in individual cushion pins for forming Aluminum alloy (A6111-T4, sheet thickness = 1 mm)Pin 123465789101114121315Pin locations and numbering
36Experimental validation of BHF prediction by FE simulation Case studies in process simulationMulti-point Control systems (MPC)Experimental validation of BHF prediction by FE simulationBake Hardened steel (BH210, t = 0.8 mm)No wrinkles, no tearsAluminum alloy (A6111 – T4, t = 1 mm)Minor wrinkles, no tearsDual Phase steel (DP600, t = 0.8 mm)No wrinkles, no tearsUsing a hydraulic MPC system installed in mechanical press, the auto-panel was formed successfully - with three different materials/sheet thicknesses in the same die - by only modifying BHF in individual cushion pins.
38CPF 5.1 - Evaluation of Bendability of AHSS Xi YangNimet Kardes-SeverYurdaer DemiralpDr. Changhyok Choi
39Prediction of Springback (in cooperation with Cincinnati Inc.) in V-Die Bending(in cooperation with Cincinnati Inc.)a) Before unloading b) After unloadingCalculation of springback for V-die bending samples:Bending angle under load was measured by camera.Bending angle after unloading was measured by protractor and camera.
40Prediction of Springback with FEA and BEND in V-Die Bending (in cooperation with Cincinnati Inc.)FEABENDPunchSheetV-dieSchematic of FE model in DEFORM 2DScreenshot from BEND
41Prediction of Springback With BEND in V-Die Bending (in cooperation with Cincinnati Inc.)The program BEND was developed based on the analytical model to predict the springback in air-bending. (Channel Die or V-Die)Parameters input to the programMaterial’s propertiesStrain hardening exponent (n )Strength coefficient (K )Initial yield stress (YS )Young’s modulus (E )Poisson’s ratioInitial thickness (t0)Sheet width (w0)Friction coefficient (m)Tool DimensionsPunch radiusDie radiusDie opening
42to Evaluate Formability/Fracture Stretch Bending Testto Evaluate Formability/FracturePunch diameter: mmLock BeadRound and Strip Samplebefore formingafter formingBy changing Rd and Rp, we can obtain different stress/strain conditions at fracture.
43CPF 5.2 - Prediction and Elimination of Edge Cracking of AHSS in Stretch Flanging Soumya Subramonian
44(in cooperation with US Steel and TUM) Blanking and Flanging(in cooperation with US Steel and TUM)Factors Influencing Hole Expansion•Edge quality of the hole•The method used to finish the hole (e.g. blanking, reaming, etc.)•Punch/die clearance used in blanking•Positioning of burr with respect to punch•Sheet materialHole Expansion Test• To investigate the stretch-ability of the finished edges.• A conical punch, flat bottom punch or spherical punch can be used.
45CPF 5.3 - Blanking and Shearing of Sheet Metal Soumya SubramonianTingting Mao
46Schematics of Blanking and Shearing (FEA and Experiments) (in cooperation with Tyco and Cincinnati Inc.)ShearingBlanking[www.custompartnet.com/wu/sheet-metal-shearing ]
47Blanking and Shearing (FEA and Experiments) Different Zones of Blanked EdgeZrZrZsZsZfZf(b)ZbZr: rollover zoneZs: shear zoneZf: fracture/rupture zoneZb: burr(a)Different zones of the blanked edge (a) simulations and (b) experiments
48Blanking and Shearing Critical Parameters Effects of the following parameters on the blanked edge quality and punch load/life are studied:Punch-die clearancePunch/die corner radiiStripper pressure and designPunch end geometryCoefficient of frictionPunch misalignmentSnap-thru forces / reverse loadingVibration and dynamicsSnap-thru forcesAnalysis of snap-thru forces during blanking through simulations
49CPF 5.5 - Hot Stamping of Boron Steels Eren Billur
50Introduction/Hot stamping - Developed for automotive applications in the 80’s- Fast growing and an evolving technology for manufacturing crash resistant, light weight parts with reduced springbackParts manufactured using hot stamping
51Introduction/Technology Overview - Manganese Boron steel (22MnB5) has ferritic pearlitic microstructure in as received condition.- These blanks are heated to austenitisation temperature(~950°C) for 5 minutes.- The heated blanks are formed and quenched in the press at a cooling rate higher than 27K/sec.- Quenching changes the microstructure from austenite to martensite and the final part is hardened and has an ultimate tensile strength of around 1500 MPa.
52Introduction/Direct Hot Stamping Direct hot stamping process
53Partners/Supporters National Science Foundation (NSF) - Supporting CPF/finite element simulations of hot stamping.IMRA , Japan- Data base of references and information in hot stamping.POSCO, South KoreaTooling System Group, USACOSKUNOZ (die maker), Turkey- Providing geometry and experimental data on example hot stamped components (details are proprietary).
54International Co-operation CPF maintains good relationship with several leading research institutes active in Hot Stamping technologyLulea University of Technology, Sweden (Prof. Akerstrom)University of Erlangen-Nuremberg, Germany (Prof. Merklein)Leibniz University, Hannover (Prof. Behrens)University of Padova, Italy (Prof. Bariani)Tech.Univ.Graz,Austria (Prof. Kolleck)Toyohashi University of Technology, Japan (Prof. Mori)Technical University of Munich, Germany (Prof. Hoffman)Dortmund University of Technology, Germany (Prof. Tekkaya)
55FE Simulation of Hot Stamping Status / UpdateVarious companies/research groups are using combination of different FE codes like LS-Dyna, ABAQUS, PAMSTAMP, FORGE, MSC. Marc, AUTOFORM for simulating the entire hot stamping processOur StrategyUse PAMSTAMP and DEFORM 3D to predict-Temperature distribution-Thickness distribution-Metal flow-Elastic tool deflection-Cooling channel optimizationSimulate and compare results with example parts a) from literature b) provided by our partner companies
56Case Study-1/ AUDI B-Pillar Section -Bench Mark problem-3 given in Numisheet D section of the part is simulated. -The objective is to predict in the formed part: (a) thickness distribution, (b) hardness distribution, (c) potential defects.Tooling for hot stamping of B-Pillar
57Case Study-1/ AUDI B-Pillar Section Input geometries for simulationDiePunchAssemblyBlankBlank holderReference: Benchmark problem-3, Numisheet 2008
58Case Study-1/ AUDI B-Pillar Section Top die (75 C)22 MnB5 Blank (810 C)Blank holder(75 C)Final simulation setupPunch (75 C)Initial simulation setupA critical section of the B-Pillar is chosen for 2-dimensional simulation (DEFORM 2D /Variable mesh density)
59Case study-2/ Cooling Channel Design -For this case study, the geometry used in the case study-2 was chosen.-Heat transfer module available in DEFORM is used for simulation-Different combination of cooling channel configurations and examples from the literature are simulated to achieve uniform cooling and martensite microstructureTemperature distribution at the end of press stroke
60Future plans---Develop a simplified and practical procedure to simulate the entire hot stamping process with reasonable accuracy using commercial codes PAMSTAMP, LS-Dyna and DEFORM (predict thinning, defects, hardness)--Develop a simulation procedure to predict tool and part dimensions during hot pressing and correct the tool surface profile to obtain accurate part dimensions and desired hardness distribution (uniform or variable)--Estimate residual stresses in the part after hot stamping, quenching and cooling
61CPF 5.6 - Applications of Servo Drive Presses in Stamping Adam Groseclose
62Servo-Drive Characteristics 1/2 Precise ram position and velocity control, anywhere in strokeAdjustable stroke length (TDC and BDC)Ram position/ velocity can be synchronized with automatic part transferIn deep drawing, cycle times can be shorter than in mechanical pressesConsiderable savings in energyDwell at BDC/ restriking/ vibrating and variable blank holder force (BHF)Max. motor torque available during the entire stroke
63Servo-Drive Characteristics 2/2 The flexibility of slide motion in servo drive (or free motion) presses. [Miyoshi, 2004]
64Servo-Drive Mechanisms Low Torque/ High RPM Motors Use Ball Screws or/and Linkage MechanismsHigh Torque/ Low RPM Motors Use Existing Crank and/or Link Press Drives
65Low RPM/High Torque Motor Drive Power SourceBalancer tankMain gearServomotorCapacitorDrive Shaftb) Stroke-Time program for warm forming of Al and Mg sheeta) C-Frame Servo Press (Aida)
66Modern Stamping Lines Using Large Servo-Drive Presses BMW- Leipzig and Regensburg (Germany)/ 2500 ton servo-drive drawing press (Schuler)/ 17 SPM (2009)HONDA- Suzuka (Japan)/ 2500 ton servo-drive drawing press (Aida)/ 18 SPM (2009)New large press lines are plannedBMW-Schuler- 2011HONDA-Aida- 2011
67Schematic of Servo-press line (Aida/Honda) 2500 ton/ 18 SPM draw press (2009)Improved FormabilityImproved ProductivityEnergy-Saving・System with optimized press forming requirements for each product・Press-to-Press Loading Motion: System is optimized for each product.・Die cushions have an energy regeneration system
69Applications- Deep Drawing 1/3 Comparison between the slide motions of an 1100 mechanical and servo drive press for identical slide velocity during forming [Bloom, 2008].
70Applications- Deep Drawing 2/3 Decrease in cycle time by reducing the stroke length and operating the servo press in “pendular” mode (progressive die stamping, 200% increase in output) [Bloom, 2008]
71Applications- Deep Drawing 3/3 Decrease in cycle time as well as in impact speed using a servo press (150% increase in output) [Bloom, 2008]
72Side Panel Outer Deep Drawing Case Example (Honda/Aida)
73High-speed/ High Accuracy Servo-Press (Honda/Aida)
74Servo-Hydraulic Cushion 1/2 (Courtesy-Aida)Die Cushion Force (kN)Elimination of Pressure Surge in the Die Cushion
75Servo-Hydraulic Cushion 2/2 (Courtesy-Aida)During Down Stroke, Cushion Pressure Generates Power
76Optimization of Ram Velocity for Deep Drawing with Servo-Drive Presses New CPF Project- in cooperation with the University of Darmstadt (Germany)ObjectiveDevelop a methodology to optimize the ram velocity during deep drawing of sheet metal parts with a servo-drive press.
77SummaryProcess simulation using FEA is state of the art for die/process design. Determination of reliable input parameters [material properties /interface friction conditions] is a key element in successful application of process simulation.Advanced FE simulation + reliable input data helps to predict process parameters for forming the part and save tryout/setup time, cost, material & energy.Multi-point control (MPC) die -cushion systems offer high flexibility in process control, resulting in considerable improvement in formability. MPC systems offer advantages in forming high strength materials.
78SummaryWarm forming of selected Al- and Mg- alloys shows improvement in formability at temperatures in the range of °C. Reliable flow stress data at elevated temperature is required as an input for accurate FE simulation of the warm forming process. Considerable research on warm forming process and its application to production is in progress.Hot stamping technology will increase rapidly (Process simulation and die design/manufacturing are major issues).Electric/Mechanical servo-drive presses will be increasingly used, also in higher tonnages (2,000-4,000 tons).
79Summary/QuestionsCPF is supported by the National Science Foundation and 10+ member companies.With a staff of 20 (post docs, PhD students, MS students), CPF is conducting R&D in metal forming, with emphasis on forming AHSS.CPF is maintaining close contacts with many other forming research labs, world wide.For questions, please contact Taylan Altan or Linda AnastasiFor detailed information, please visit and79