1 / 28

Sheet Metalworking

Sheet Metalworking. Cutting Operations. Shearing by two sharp cutting edges. Plastic deformation penetration fracture. Shearing, Blanking and Punching. Shearing - Cutting on sheet-metal with straight edges. Blanking - Cutting sheet-metal with a closed contour.

allen-kinney
Download Presentation

Sheet Metalworking

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sheet Metalworking

  2. Cutting Operations Shearing by two sharp cutting edges. Plastic deformation penetration fracture

  3. Shearing, Blanking and Punching Shearing - Cutting on sheet-metal with straight edges. Blanking - Cutting sheet-metal with a closed contour. Punching - Making holes on sheet-metal.

  4. Sheet-metal Cutting c = at c = clearance a = allowance t = thickness Blanking: Blanking punch dia. = Db- 2c Blanking die dia. = Db Punch Hole punch dia. = Db Hole die dia. = Db+ 2c 0.25 to 1.5

  5. Sheet-metal Cutting Small clearance Cutting force = StL S = Shear strength of sheet-metal t = Sheet-metal thickness L = Length of cutting edge or, Cutting force = 0.7TtL T = Ultimate tensile strength of sheet-metal Large clearance

  6. Sheet-metal Cutting Operations Cut-off Parting Slotting Perforating Notching / Seminotching

  7. Sheet-metal Cutting Operations Fine blanking - close tolerances and smooth edges in one step. Trimming - Cutting operation to remove excess metal Shaving - Shearing with very small clearance to obtain accurate dimensions., secondary or finishing operation.

  8. Bending V- bending Edge - bending

  9. Bending Analysis BA = 2  A( R + Kbat ) / 360 where BA = bending allowance, A = bend angle, R = bend radius, t = stock thickness, Kba = stretch factor. For R< 2t, Kba= 0.33 ; for R 2t, Kba= 0.5. Spring back, where A’ = include angle of sheet-metal part A’b = include angle of bending tool w = width of sheet-metal Bending force D = die opening dimension Kbf = 1.33 V-bending Kbf = 0.33 edge bending

  10. Bending Analysis Spring back Die-opening dimension

  11. Bending Operations Straight flanging Stretch flanging Shrink flanging Hemming Seaming Curling

  12. Bending Operations Channel bending U-bending air-bending Offset-bending Corrugating Tube forming

  13. Drawing c = Clearance Db = blank diameter Dp = Punch diameter Rd = die corner radius Rp = Punch corner radius F = drawing force Fh = holding force

  14. Deep Drawing Initial step bending of edge straightening of side wall Thinning and drawing final cup shape

  15. Drawing Analysis Drawing ratio,  2.0 where Db = blank diameter Dp = punch diameter t = thickness of the starting blank Reduction,  0.5 Thickness to diameter ratio,  1% Drawing force, , max. at 1/3 stroke. Holding force, Holding pressure may be set at 0.015 of the yield strength T = Tensile strength, Y = Yield strength, Rd = die corner radius

  16. Drawing Analysis • Blank diameter can be calculated from the conservation of volume based on the final volume of the part. • If the limits on the drawing ratio, reduction and thickness-to-diameter ratio are exceeded, the blank must be drawn in steps or having annealing between the steps. • Process optimization: • Punch and die corner radii • friction • depth of draw (per step) • material characteristics

  17. Drawing Defects a) Wrinkling in flange - small holding force b) Wrinkling in the wall - insufficient holding force, wrinkling initially occurring on the flange. c) Tearing - high stress, sharp die radius d) Earing - anisotropy of the material e) Surface scratches - Die or punch not having a smooth surface, insufficient lubrication

  18. Other Sheet-metal Operations Ironing - squeezing and drawing in conjunction Corning & Embossing - to produce surface details Lancing - combination of cutting and forming

  19. Other Sheet-metal Operations Rubber forming processes: Guerin process - low cost, small volume, pressure up 10 MPa. Hydroforming - Higher pressure, up to 100 MPa.

  20. Dies Components of a punch and die for blanking operation

  21. Dies Progressive dies and final part

  22. Press Press are driven mechanically or hydraulically. crankshaft Knuckle joint eccentric

  23. Stretch Forming Stretching and forming with a die at the same time.

  24. Roll Forming Similar to the the rolling process but working on sheet-metal or tubes.

  25. Spinning Conventional spinning Shear spinning - thinning and bending occur at the same time.

  26. Spinning Tube spinning - similar to shear spinning but working on a tube.

  27. High Energy Forming Explosive forming Electrohydraulic forming Electromagnetic forming

  28. Tube Bending Stretch bending Drawing bending Compression bending R/D  3.0 with mandrel R/D  1.5 without mandrel

More Related