**2.2.5 Addendum construction**

26 Industrial Design – New Frontiers

The most important drawing goal is to draw a raw metal piece into a desired high-quality shape. This quality is markedly affected by the orientation of stamping when the sheet metal panel is punched and is based on symmetry, equal-angle, and equal-depth not exceeding an

To prevent sliding and wrinkling during drawing operations, a binder is used to hold the piston and upper mold. A binder should be the same height as the product-out face and be smooth and simple in terms of geometry. A binder has a straight line, a curved section, and

The shape of a sheet metal automobile panel is typically complex and irregular, resulting in difficulty achieving uniform forces on the die face during drawing operations. To solve this problem, an addendum is introduced that uses various section curves (Fig. 10) to make forces uniform. Additionally, the convenience of subsequent operations is also a concern

The design of an addendum requires determination of the trimming position, section type, and its size. Fig. 11 provides a detailed explanation of Fig. 10(b). A 3–5mm line is usually extended from the product-in face to avoid cracks from bending. An addendum is typically shaped like stairs to facilitate trimming. The bending angle of an addendum should be as

**2.2.2 Analysis of stamping direction** 

appropriate value.

**2.2.3 Binder design** 

different types of boundaries.

Fig. 10. Common section types

Fig. 11. Stair-like section curve

small as possible.

and can affect the choice of section type.

**2.2.4 Addendum design** 

Designers first construct the parting line as a limitation in subsequent design steps (Fig. 12). The addendum surface is then designed, which is composed of a section curve and connecting curve (Dy et al., 2008). The section curve determines how the addendum is shaped and is a concern for subsequent operations. The connecting curve connects section curves to produce a smooth surface. Finally, chamfer at the parting line.

When using programs to construct an addendum, the trimming point should lie on the trimming face and a connected curve along the shape of the sheet metal panel should be used to make its surface smooth. The design platform in this study is based on the SpringSolid system developed by the Solid Model Laboratory, National Taiwan University and written in Java.

Fig. 12. Addendum construction
