TABLE OF CONTENTS It is common practice for the tool designer to work out a preliminary progression, sometimes freehand, with the successive stations superimposed on one another, resulting in what is often called a flower, as in Fig 4.5 (the product part of Fig. 2.1). The progression is certainly not final, as there are often revisions and changes as the designer gets into the detail of the tool design. The progression will reflect the designer s experience, his judgment of the risk, the tooling cost limitations, the tolerance constraints, length of run, the skill level of the machine operators, etc., so the progression may take a variety of different forms depending on the individual designers and how they handle these various factors.
The progression shown in Fig. 4.6 might appear to be very efficient, and require fewer stands because both radii are formed concurrently and at the same rate. The result is that the wings stay horizontal. In general, this is not good practice for the reason that in this attitude the wing is effectively a beam which provides the maximum possible resistance to the bending required to accomplish the lateral movement (see Fig. 4.7) There is lateral movement required in varying degrees between each pair of stations, so the problem is repeated between each pair of stations.
Sometimes the progression will work if the material is very light gauge, or if the lateral movement is very small because the net dimensions of the shape are...
