FEA OF SHEET METAL FORMING PROCESSES

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					                          FEA OF SHEET METAL FORMING PROCESSES
                                                                 E. ÖNDER, Ç. SÖNMEZ, , A. E. TEKKAYA




                             AIM                                                                                                                     METHOD                                                        PROCESS PARAMETERS
                                                                                                                                                                                                                                               TOOL GEOMETRY
                                                                                                    wFor these investigations the FE-                                                                                                          wDie Radius / Shape
                                                                                                    package PAM-STAMP is used.                                                                                          PUNCH                  wPunch Radius / Shape
The aim of these projects is the finite                                                                                                                                                                                                        wBlank Radius
                                                                                                                                                                                                                                               wPunch Fillet Radius
element analysis of sheet metal                                                                     wFor verification of the basic cup                                                                        BH                          BH   wDie Fillet Radius
                                                                                                    drawing analyses, NUMISHEET 2002                                                                                                           PROCESS PARAMETERS
forming processes .                                                                                                                                                                                                                            wPunch Speed
                                                                                                    cup drawing benchmarks are used.                                                                                                           wDrawing Depth
One project deals with the                                                                                                                                                                                    DIE                       DIE    wLubrication
comparison of the deep drawability                                                                  wVa r i o u s p a r t s f r o m d i f f e r e n t                                                                                          wBlank Thickness
                                                                                                                                                                                                                                               wBlankholder Force
of steel and aluminum, the other                                                                    manufacturers are analysed to achieve                                                                                 BLANK SHEET
                                                                                                                                                                                                                                               MATERIAL PROPERTIES
                                                                                                    experimental backup.                                                                                                                       wDensity
focuses on hydroforming processes                                                                                                                                                                                                              wElastic Modulus
                                                                                                                                                                                                            To obtain a successful end-        wFlow Curve
in general.                                                                                         wSome commercial processes will be                                                                      product, all these parameters      wMax. Elongation
                                                                                                    inspected for optimization.                                                                             must be carefully controlled       wAnisotropy
                                                                                                                                                                                                                                               wMicrostructure




                                 SIMULATIONS                                                                                                                                                          PROCESS OPTIMIZATION
                                                       In conventional deep drawing, the
                                                       punch and the die are solid; in                                                                                  Wr i n k l i n g d u e t o a n
                                          Punch
                                                       hydroforming / aquadrawing etc. the                                                                              insufficient blank holding
                                          Blank Holder punch may be a fluid (whereas the                                                                                force (10kN) is prevented
                                          Die          fluid pressure supplies the                                                                                      by increasing the blank
                                                       deformation force) or the die cavity                                                                             holding force to 15kN.
                                          Blank Sheet may be filled with a liquid medium
                                                       (whereas the product shape
                                                       depends only on the punch shape).


  If the geometry is suitable,                                                                                                                                                                                                                  A circular part shows
  symmetry conditons may also                                                                                                                                                                                                                   excessive thinning since
                                                                                                                                                                                                                                                the LDR is exceeded,
  used for the analyses, but since                                                                                                                                                                                                              when the drawing depth
  anisotropic effects and/or wrinkling                                                                                                                                                                                                          is reduced, the product is
  phenomena are also present this is                                                                                                                                                                                                            succesful.
  not preferred most of the time.




                                                                                                             SAMPLE RESULTS
                                          Flange profile at the end of the drawing                                                          Force - displacement curves for 90mm
Thickness contour of deformed aluminum
                                          operation for 90mm aluminum and steel                                                             Steel and Aluminum blanks - identical
sample 90mm blank 1mm initial thickness                                                                                                                                                                                                        Excessive thinning and wrinkling
                                          blanks - identical process parameters                                                             process parameters
                                                                                                                                                                                                                                               in a commercial complex part in
                                                                                                                                                                                                                                               hydroforming and aquadrawing
                                                                                                                                                                                                                                               operations.
                                                                            80
                                                              y Position [mm]
                                                                                               Steel Blank
                                                                                                                       Punch Force [N]




                                                                                                                                         80000
                                                                                               Aluminum Blank
                                                                           60
                                                                                                                                         70000


                                                                           40                                                            60000


                                                                                                                                         50000
                                                                           20

                                                                                                                                         40000

                                                                            0
                                                                                                                                         30000                                 Steel Blank
                                            -80   -60   -40         -20          0   20   40         60           80
                                                                                                x Position [mm]
                                                                                                                                                                               Aluminum Blank
                                                                           -20                                                           20000


                                                                                                                                         10000
                                                                           -40

Thickness contour of deformed steel                                                                                                         0
                                                                                                                                                 0   5   10   15   20     25       30        35       40
sample 90mm blank 1mm initial thickness                                    -60
                                                                                                                                                                                        Punch Stroke [mm]



                                                                           -80




                                          Since aluminum and steel have different anisotropic
                                          behaviors, same processes utilizing aluminum and
                                          steel blanks result in completely different end-
                                          products.