multi-modal interactions
1 like628 views
Sheet metal processing involves cutting, forming, and joining operations to shape raw sheet metal into parts. Common sheet metal processes include shearing, punching, bending, and deep drawing. Shearing uses large scissors to cut sheet metal to size. Punching and blanking cut out shapes from sheet metal using round or rectangular punches and dies. Bending forms sheet metal into angles and curves. Deep drawing stretches sheet metal over forming dies to create containers and pots. Sheet metal parts often involve combinations of these operations to create complex shapes.
![Bending
Body of Olympus E-300 camera
component with multiple bending operations
[image source: dpreview.com]
component with punching,
bending, drawing operations](https://image.slidesharecdn.com/sheetmetalforming-130916134850-phpapp02/85/multi-modal-interactions-9-320.jpg)
![Sheet metal parts with combination of operations
Body of Olympus E-300 camera
component with multiple bending operations
[image source: dpreview.com]
component with punching,
bending, drawing operations](https://image.slidesharecdn.com/sheetmetalforming-130916134850-phpapp02/85/multi-modal-interactions-24-320.jpg)
multi-modal interactions
- 1. Traditional Manufacturing Processes Casting Forming Sheet metal processing Cutting Joining Powder- and Ceramics Processing Plastics processing Surface treatment
- 2. Sheet Metal Processes Raw material: sheets of metal, rectangular, large Raw material Processing: Rolling (anisotropic properties) Processes: Shearing Punching Bending Deep drawing Hydroforming
- 3. Shearing A large scissors action, cutting the sheet along a straight line Main use: to cut large sheet into smaller sizes for making parts.
- 4. Shearing • Shearing is a process for cutting sheet metal to size out of a larger stock such as roll stock. Shears are used as the preliminary step in preparing stock for stamping processes. • Material thickness ranges from 0.125 mm to 6.35 mm (0.005 to 0.250 in). The dimensional tolerance ranges from ±0.125 mm to ±1.5 mm (±0.005 to ±0.060 in). • The shearing process produces a shear edge burr, which can be minimized to less than 10% of the material thickness. The burr is a function of clearance between the punch and the die (which is nominally designed to be the material thickness), and the sharpness of the punch and the die.
- 5. Blanking / Punching • Blanking and punching are similar sheet metal cutting operations that involve cutting the sheet metal along a closed outline. • If the part that is cut out is the desired product, the operation is called blanking and the product is called blank. If the remaining stock is the desired part, the operation is called punching.
- 7. Cutting tool is a round/rectangular punch, that goes through a hole, or die of same shape F ∝ t X edge-length of punch X shear strength Punch die sheet crack (failure in shear) clearance die piece cut away, or slug t F ∝ t X edge-length of punch X shear strength Punch die sheet crack (failure in shear) clearance die piece cut away, or slug t
- 8. Punching Main uses: cutting holes in sheets; cutting sheet to required shape typical punched part nesting of parts Exercise: how to determine optimal nesting?
- 9. Bending Body of Olympus E-300 camera component with multiple bending operations [image source: dpreview.com] component with punching, bending, drawing operations
- 16. Typical bending operations and shapes (a) (b)
- 17. Sheet metal bending Planning problem: what is the sequence in which we do the bending operations? Avoid: part-tool, part-part, part-machine interference
- 18. Bending mechanics R = Bend radius Neutral axis α L = Bend length This section is under extension This section is in compression Bend allowance, Lb = α(R + kT) T = Sheet thickness R = Bend radius Neutral axis α L = Bend length This section is under extension This section is in compression Bend allowance, Lb = α(R + kT) T = Sheet thickness Bending Planning what is the length of blank we must use? Ideal case: k = 0.5 Real cases: k = 0.33 ( R < 2T) ~~ k = 0.5 (R > 2T)
- 19. Bending: cracking, anisotropic effects, Poisson effect Bending plastic deformation Bending disallow failure (cracking) limits on corner radius: bend radius ≥ 3T Engineering strain in bending = e = 1/( 1 + 2R/T) effect of anisotropic stock Poisson effect Exercise: how does anisotropic behavior affect planning?
- 21. Bending: springback 134 3 + − = ET YR ET YR R R ii f i How to handle springback: (a) Compensation: the metal is bent by a larger angle (b) Coining the bend: at end of bend cycle, tool exerts large force, dwells coining: press down hard, wait, release Initial Final R i Rf i f αf αi T
- 22. Deep Drawing die die die die die punch punch punch punch blank part blank holder (a) (b) (c) (d) (e) Examples of deep drawn parts die die die die die punch punch punch punch blank part blank holder (a) (b) (c) (d) (e) die die die die die punch punch punch punch blank part blank holder (a) (b) (c) (d) (e) Examples of deep drawn parts Tooling: similar to punching operation, Mechanics: similar to bending operation Common applications: cooking pots, containers, …
- 24. Sheet metal parts with combination of operations Body of Olympus E-300 camera component with multiple bending operations [image source: dpreview.com] component with punching, bending, drawing operations