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An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bendin

An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies. Zafer Tekiner Accepted 25 July 2003 Presented by Jared Moyer September 22, 2004. Bending Background. Used anciently-5000 BC Utensils and jewelry

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An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bendin

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  1. An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25 July 2003 Presented by Jared Moyer September 22, 2004

  2. Bending Background Used anciently-5000 BC Utensils and jewelry A common shaping process today Seams, flanges Automotive-car bodies Aircraft fuselages Beverage can Metal desks

  3. Modern forms

  4. Advantages • Low cost • Good strength • Light weight • Formability characteristics • no necking or tearing • Versatile shapes

  5. Disadvantages • Cracking • Springback • Sheets • Rod • Wire • bars SB = (A’ – Ab’)/ Ab’

  6. Reducing Springback • Over bending part • Elevated temperatures • Bottoming the punch • High-localized compressive stresses between the punch and die surface • Stretch bending • Part is in tension while being bent

  7. Purpose of Paper • Find a springback values • Bending die designers • Acceptable tolerances • Experimental methods • Time • Money

  8. Test Set Up • Several materials: Steel, Copper, Brass, Aluminum, Galvanized and stainless steels • Dimensions: 25 mm x 50 mm • Different thicknesses: .5, .75 & 1.00 mm • Measured bending by optical profilometer (1 min) • Used four different methods • Results graphed by Microsoft Excel software

  9. Forces Needed • Force Equations • C = 1 + (4*T/W) • P*v = C (B*T^2*dd*b-/W) x 10

  10. Method 1 • Punch doesn’t touch die corners • Gap thickness between punch and die equaled to sheet metal thickness • Punched left for 20 sec. • Repeated each material and thickness

  11. Method 1 Results

  12. Method 1 overall results

  13. Method 2 • Punch on the sheet metal • No maintaining load

  14. Method 2 Results

  15. Method 2 overall Results

  16. Method 3 and 4 • Method 3 • No gap between punch and die • Load left for 20 sec • Method 4 • No gap between punch and sheet metal • No holding load • Results • Too complicated • Crushing material • Depth of descending punch not considered

  17. Conclusions • Changed with material and die • Reduced by leaving loads • Developed equations help produce more precise results

  18. My conclusions • Are the springback values valid with multiple bends? • Experiments have been preformed • Machinists use charts

  19. References • Fundamentals of Modern Manufacturing, Mikell P. Groover • Manufacturing Engineering and Technology, Kalpakjan and Schmid

  20. Questions

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