Steels_ Metallurgy and Applications, Third Edition

Low-carbon stdp steels 35

Finished shape)

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9 Profiles of top, bottom and side rolls

Roller die cold forming

Figure 1.34 A schematic diagram showing the formation of a shape from a coil of raw
material to finished configuration (After Ferry 59)

............. .,

Figure 1.35 A flower pattern showing the progressive change of shape by rolling to form
a top hat section (After Cain ~)

which incrementally change the shape until the final shape is obtained. Most of
the deformation is by bending, with the result that very little change in thickness
occurs. Narrow strips may be converted into structural sections, whereas wide
strips may be converted into profiled sheets for cladding applications mainly for
building applications for which the profile imparts increased rigidity and load-
bearing capability.
Figure 1.34 gives an example of the profiles of top bottom and side rolls that
are required to give a particular structural section, whereas Figure 1.35 illustrates
the progressive change in shape through each roll as a strip is roll formed to give
a top hat section. This type of diagram is known as a flower pattern. Some of
the profiles that are used for building applications are illustrated in Figure 1.122
at the end of this chapter.

Finite element modelling

Although the FLD provides a valuable guide to forming behaviour and can assist
in component design, the approach is still empirical. Additionally, it has limita-
tion~b~, virtue of the fact that the strain paths in commercial pressings may be