An experimental study on the examination of springback of sheet metals with several thicknesses and...
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![Page 1: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/1.jpg)
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
![Page 2: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/2.jpg)
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
![Page 3: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/3.jpg)
Modern forms
![Page 4: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/4.jpg)
Advantages
• Low cost
• Good strength
• Light weight
• Formability characteristics• no necking or tearing
• Versatile shapes
![Page 5: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/5.jpg)
Disadvantages
• Cracking
• Springback– Sheets
– Rod
– Wire
– barsSB = (A’ – Ab’)/ Ab’
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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
![Page 7: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/7.jpg)
Purpose of Paper
• Find a springback values – Bending die designers– Acceptable tolerances
• Experimental methods• Time
• Money
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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
![Page 9: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/9.jpg)
Forces Needed• Force Equations
– C = 1 + (4*T/W)
– P*v = C (B*T^2*dd*b-/W) x 10
![Page 10: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/10.jpg)
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
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Method 1 Results
![Page 12: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/12.jpg)
Method 1 overall results
![Page 13: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/13.jpg)
Method 2
• Punch on the sheet metal
• No maintaining load
![Page 14: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/14.jpg)
Method 2 Results
![Page 15: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/15.jpg)
Method 2 overall Results
![Page 16: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/16.jpg)
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
![Page 17: An experimental study on the examination of springback of sheet metals with several thicknesses and properties in bending dies Zafer Tekiner Accepted 25.](https://reader036.fdocuments.net/reader036/viewer/2022062714/56649d575503460f94a36050/html5/thumbnails/17.jpg)
Conclusions
• Changed with material and die
• Reduced by leaving loads
• Developed equations help produce more precise results
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My conclusions
• Are the springback values valid with multiple bends?
• Experiments have been preformed
• Machinists use charts
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References
• Fundamentals of Modern Manufacturing, Mikell P. Groover
• Manufacturing Engineering and Technology, Kalpakjan and Schmid
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Questions