The Basic Processes For Sheet Metal Fabrication - Deep Drawing (3)

- Jun 12, 2018 -

4. Deep Drawing Parts

**4.1** Requirements for fillet radius between bottom and straight wall of deep drawing parts

As shown in the figure below, the fillet radius between the bottom section of the deep drawing parts and the straight wall should be larger than the plate thickness: r1≥t. In order to make the deep drawing process more smoothly, r1=(3~5)t is usually taken.The maximum radius of the round angle should be less than or equal to 8 times the thickness of the plate: r1≤8t.

**Figure 5.1.1 The radius of the fillet of the deep drawing parts**

**4.2** The radius of fillet between the flange and the wall of a deep drawing part

The fillet radius between the flange and the wall of the deep drawing parts should be 2 times larger than the plate thickness: r2≥2t. In order to make the deep drawing process more smoothly, r2= (5~10)t is usually taken.The maximum flange radius should be less than or equal to 8 times the thickness of the plate, that is r2≤8t. (See Figure 5.1.1 above)

**4.3** The inner diameter of a circular deep drawing part

D ≥d+10t is taken for the inner diameter of a circular deep drawing part, so that the pressing plate does not wrinkle when it is deep drawing. (see Figure 5.1.1 above)

**4.4** The radius of the fillet between two adjacent walls of a rectangular deep drawing part

The fillet radius between two adjacent walls of rectangular deep drawing parts should be r3 ≥3t. In order to reduce the drawing times, r3 ≥H/5 should be taken, in order to finish by once processing.

**Fig. 5.4.1 Radius of fillet between two adjacent walls of rectangular deep drawing parts**

**4.5** Dimensional relationship between the height and diameter of the flangeless circular deep drawing part that processed by one-time drawing

The ratio of height H to diameter D should be less than or equal to 0.4 when forming a circular flangeless deep drawing part.

Dimensional relationship between the height and diameter of the flangeless circular deep drawing part that processed by one-time drawing

**4.6** Attentions in dimensioning size on design drawings for drawing process

Due to the different stress on the drawing parts, the thickness of the drawing material changes. In general, the bottom center keeps the original thickness, the material at the bottom corner is thinner, the top material that is closer to the flange becomes thicker, and material around the round angle are thickened on the rectangular drawing parts.

**4.6.1** Standard method for dimentioning product size of deep drawing parts

When designing the deep drawing products, the size of the product on drawings should be clearly indicated that the external dimensions or internal dimensions must be guaranteed, and the internal and external dimensions cannot be simultaneously marked.

**4.6.2** Dimensioning method for tolerance of deep drawing parts

Symmetric deviation: tolerance of the inner radius of the concave and convex arc of the deep drawing parts and the height of a cylindrical deep drawing part by primary forming.The deviation value is half of the absolute value of the national standard 16 grade precision tolerance, and marked by ±.

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