deep drawing lec 1
Post on 09-Dec-2015
85 Views
Preview:
DESCRIPTION
TRANSCRIPT
Deep Drawing
Deep drawing Deep drawing defects Deep drawing operations Deep drawing calculations
DR. Ramadan EL-Gamsy
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
DR. Ramadan EL-Gamsy
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
Examples
DR. Ramadan EL-Gamsy
Examples
DR. Ramadan EL-Gamsy
Deep drawing
DR. Ramadan EL-Gamsy
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
Defects in Drawing
DR. Ramadan EL-Gamsy
Drawing dies
DR. Ramadan EL-Gamsy
DR. Ramadan EL-Gamsy
Deep Drawing for cans
DR. Ramadan EL-Gamsy
Deep drawing with flange
DR. Ramadan EL-Gamsy
Deep Drawing
DR. Ramadan EL-Gamsy
Drawing steps
DR. Ramadan EL-Gamsy
Drawing steps
DR. Ramadan EL-Gamsy
Redrawing die
DR. Ramadan EL-Gamsy
Deep Drawing Calculations
Blank diameter Diameter ratio Force calculations
DR. Ramadan EL-Gamsy
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
Blank volume
DR. Ramadan EL-Gamsy
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
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
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
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
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
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
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
Drawing with ironing
DR. Ramadan EL-Gamsy
top related