deep drawing lec 1

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Deep Drawing Deep drawing Deep drawing defects Deep drawing operations Deep drawing calculations DR. Ramadan EL-Gamsy

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Page 1: Deep Drawing Lec 1

Deep Drawing

Deep drawing Deep drawing defects Deep drawing operations Deep drawing calculations

DR. Ramadan EL-Gamsy

Page 2: Deep Drawing Lec 1

Deep Drawing

Parts are made by having punch forces on a flat sheet-metal blank into a die cavity, a process called deep drawing

Also used to make parts that are shallow or have moderate depth

A round sheet-metal blank is placed over a circular die opening and is held in place with a blank holder

DR. Ramadan EL-Gamsy

Page 3: Deep Drawing Lec 1

DR. Ramadan EL-Gamsy

Page 4: Deep Drawing Lec 1

If the depth of the item created is equal to or greater than its radius, then the metal forming process called deep drawing.

DR. Ramadan EL-Gamsy

Page 5: Deep Drawing Lec 1

Examples

DR. Ramadan EL-Gamsy

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Examples

DR. Ramadan EL-Gamsy

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Deep drawing

DR. Ramadan EL-Gamsy

Page 8: Deep Drawing Lec 1

Defects in Drawing

A number of defects in drawing can occur, which include: (a) Wrinkling in the flange occurs due to compressive buckling in the circumferential direction (blank holding force should be sufficient to prevent buckling from occurring). (b) Wrinkling in the wall takes place when a wrinkled flange is drawn into the cup or if the clearance is very large, resulting in a large suspended (unsupported) region. (c) Tearing occurs because of high tensile stresses that cause thinning and failure of the metal in the cup wall. Tearing can also occur in a drawing process if the die has a sharp corner radius. (d) Earring occurs when the material is anisotropic, i.e. has varying properties in different directions. (e) Surface scratches can be seen on the drawn part if the punch and die are not smooth or if the lubrication of the process is poor.

DR. Ramadan EL-Gamsy

Page 9: Deep Drawing Lec 1

Defects in Drawing

DR. Ramadan EL-Gamsy

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Drawing dies

DR. Ramadan EL-Gamsy

Page 11: Deep Drawing Lec 1

DR. Ramadan EL-Gamsy

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Deep Drawing for cans

DR. Ramadan EL-Gamsy

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Deep drawing with flange

DR. Ramadan EL-Gamsy

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Deep Drawing

DR. Ramadan EL-Gamsy

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Drawing steps

DR. Ramadan EL-Gamsy

Page 16: Deep Drawing Lec 1

Drawing steps

DR. Ramadan EL-Gamsy

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Redrawing die

DR. Ramadan EL-Gamsy

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Deep Drawing Calculations

Blank diameter Diameter ratio Force calculations

DR. Ramadan EL-Gamsy

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Blank dimensions

Trimming allowance

DR. Ramadan EL-Gamsy

Allowances for edge trimming for cylindrical cups without flange. Total height in

mm Allowance for height to diameter ration h/d

0.5 -0.8 0.8 -1.6 1.6 -2.5 2.5 -4.0 10 1.5 1.8 2.3 3 20 2.2 3 3.7 4.5 50 3.5 4.5 6 7

100 5 6.5 8.5 10 150 6.5 8 10 12 200 7.5 9.3 12 15 250 9 11 13.5 16 300 10 13 15 18

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Blank volume

DR. Ramadan EL-Gamsy

Page 21: Deep Drawing Lec 1

Blank Size Determination

For final dimensions of drawn shape to be correct, starting blank diameter Db must be right

Solve for Db by setting starting sheet metal blank volume = final product volume

To facilitate calculation, assume negligible thinning of part wall

DR. Ramadan EL-Gamsy

Page 22: Deep Drawing Lec 1

Number of stages

Maximum height to diameter ratio h/d for S/D %

No of drawing stages

Relative materials thickness s/D % 2 - 1.5 1.5 -1.0 1.0 - 0.6 0.6 – 0.3 0.3 – 0.1

1 0.9..0.77 0.84…0.65 0.7….5.57 0.62….0.57 0.52..0.45 2 1.88..1.54 1.6….1.32 1.36….1.10 1.13….0.94 0.96…083 3 3.5…..4.3 2.8…..2.2 2.3…..1.80 1.90….1.50 1.60…1.30 4 5.0…..4.8 4.3……3.5 3.60….2.90 2.90…2.40 2.40….2.00 5 8.9…6.6 6.6….5.1 5.20….4.10 4.10…3.30 3.30….2.70

DR. Ramadan EL-Gamsy

Page 23: Deep Drawing Lec 1

Diameter ration m

Diameter ratio m= d/d0

Diameter Ratio M

Relative materials thickness s/D % 2 - 1.5 1.5 -1.0 1.0 - 0.6 0.6 – 0.3 0.3 – 0.1

M1 0.48 – 0.5 0.5 – 0.53 0.53-0.55 0.55-0.58 0.58- 0.60 M2 0.73 – 0.75 0.75 – 0.76 0.76 – 0.78 0.78 0.79 0.79 -080 M3 0.76-0.78 0.78 – 0.79 0.79 – 0.8 0.80- 0.81 081-082 M4 0.76 -0.8 0.8 – 0.81 0.81 -0.82 0.82 -0.82 0.83 – 0.85 M5 0.8 – 0.82 0.82 -0.84 0.84- 0.85 0.85-0.86 0.86 – 0.87

DR. Ramadan EL-Gamsy

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Force calculations

Item Stage Formula Cylindrical cup without flange

1st Drawing F=π d1 s σult K1 2nd Drawing F=π dn s σult K2

DR. Ramadan EL-Gamsy

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Force Calculations

Relative materials thickness s/D %

M1 0.45 0.48 0.5 0.52 0.55 0.60 0.65 0.70 0.75 0.80

5.0 0.95 0.85 0.75 0.65 0.60 0.50 0.43 0.35 0.28 0.20 2.0 1.1 1.00 0.90 0.80 0.75 0.60 0.50 0.42 0.35 0.25 1.2 1.10 1.00 0.90 0.80 0.68 0.56 0.47 0.37 0.30 0.8 1.10 1.00 0.90 0.75 0.60 0.50 0.40 0.33 0.5 1.10 1.00 0.82 0.67 0.55 0.45 0.36 0.2 1.10 0.90 0.75 0.60 0.50 0.40 0.1 1.10 0.90 0.75 0.60 0.50

K1 for first stage drawing

DR. Ramadan EL-Gamsy

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Force Calculations

K2 for redrawing stages

Relative materials thickness s/D %

Mn 0.45 0.48 0.5 0.52 0.55 0.60 0.65 0.70 0.75 0.80

5.0 0.85 0.70 0.60 0.50 0.42 0.32 0.28 0.20 0.15 0.12 2.0 1.1 0.90 0.75 0.60 0.52 0.42 0.32 0.25 0.20 0.14 1.2 1.10 0.90 0.75 0.62 0.52 0.42 0.30 0.25 0.16 0.8 1.00 0.82 0.70 0.57 0.46 0.35 0.27 0.18 0.5 1.10 0.90 0.76 0.63 0.50 0.40 0.30 0.20 0.2 1.00 0.85 0.70 0.56 0.44 0.33 0.23 0.1 1.10 1.00 0.82 0.68 0.55 0.40 0.30

DR. Ramadan EL-Gamsy

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Die Radius

Die radius in deep drawing for first stage

Punch radius.

Stage S/D % 2.0…………1.0 1.0……..0.3 0.3…….0.1

(6…..8)S (8…..10)S (10…..15)S

S/D % > 0.6 0.6…..0.3 < 0.3

Rpunch = Rdie Rpunch = 1.5 Rdie Rpunch = 2 Rdie

DR. Ramadan EL-Gamsy

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Drawing with ironing

DR. Ramadan EL-Gamsy