1. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Sheet Metal Forming 판재 성형 Associate Professor Su-Jin KimSu-Jin Kim School of Mechanical Engineering Gyeongsang National University

2. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Sheet metal forming ( 판재성형 ) Sheet metal forming is a processes that shape a piece of sheet metal into the desired part through shearing( 전단 ) and deformation( 성형 ). It is also called pressworking, press forming, or stamping.

3. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Contents 1.[Shearing] 2.[Forming] 3.[Press Die]

4. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Cutting with Shearing ( 전단 ) Sheet metal is separated by applying shearing force using punch and die. Edge fracture & burr. Punch Sheet metal Die F Clearance Rollover Burnish Fracture Burr

5. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Cutting with shear 1.Shearing - Separating material into two parts 2.Blanking - Removing material to use for parts 3.Punching - Removing material as scrap Blanking Scrap Part Punching Part Scrap Shearing Part2 Part1

6. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Shearing Shearing cuts straight line to separate a piece of sheet metal into smaller parts.

7. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Blanking Desired part (gears, key) is removed from sheet metal. Fine blanking, applying 3 separate forces, produces smooth and flat edges with minimal burrs and tolerances. Punch Upper pressure pad Sheet metal Die Lower pressure cushion Stringer Blanking Fine blanking http://ma.gnu.ac.kr/vod/forming/Stainless_Spoon.wmvhttp://ma.gnu.ac.kr/vod/forming/Stainless_Spoon.wmv Spoon

8. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Punching Scrap(Hole, slot) is removed from sheet metal. Piercing - cylindrical punch Slotting - rectangular holes Perforating - large number of holes Notching - edge of sheet Lancing - partial cut to be bent Slitting - straight line Parting - separating a part Cutoff - separating a part

9. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Punch Force The punch force is product of shear strength of sheet metal and cross-sectional area being sheared. Punch force : F ≈ (0.7σ u )tl σ u = ultimate tensile strength t = thickness l = total length of the sheared edge t l F

10. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Estimate the force required in punching a 25 mm diameter hole through a 1.8 mm thick 5052-O aluminium sheet at room temperature. Ultimate tensile strength of it is 190 MPa. Solution F = (0.7 190 Mpa) (1.8 π 25 mm 2 ) = 18.8 kN Ex) Calulation of punch force

11. © 2011 Su-Jin Kim GNU Sheet-Metal Forming Manufacturing Processes Punch press machine Punch press bending tool http://www.youtube.com/watch?v=vdqqm0Hi7nchttp://www.youtube.com/watch?v=vdqqm0Hi7nc LVD http://www.youtube.com/watch?v=DvONyl-ncMohttp://www.youtube.com/watch?v=DvONyl-ncMo AMADA