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#052 Method of Using Standard Components (1) Method of Using Stripper Bold

Category : Die Design
August27, 2010

There are many types of stripper bolts as is shown in Fig. 1.

Fig. 1 Stripper bolts

The shapes shown here are the basic shapes, and considering fine applications, the Misumi standard components have been finely subdivided thereby widening the available choice. A stripper bolt retains the part by the length of the shaft (L) and makes the component movable. Because of this method of use, it is also called a hanging bolt, shoulder bolt, etc. Since the method of use of a stripper retention of a die with the movable stripper structure is very well known, the name stripper bolt has come into standard use.

(1) Shaft length (L)

Several stripper bolts are used for a movable stripper. If there are any fluctuations in the shaft length (L) at that time, while the head of a short bolt is contacting the head part seating surface the others will not be contacting, and hence the stripper becomes inclined thereby causing breakage of the stripper bolt. The stripper bolts used for the same part should ideally have small variations in the shaft lengths but are of the same shaft length. This is particularly important in dies for forming thin plates.

(2) Method of using stripper bolts

Figs. 2(a) and 2(b) show the methods of using stripper bolts.
The method of use shown in (a) is good. Although the form in (b) is such that the seating surface is at the bottom of the countersunk surface, it is difficult to machine accurately the Z dimension at the time of forming the countersunk, and hence fluctuations will be present. These fluctuations will have the same effect as when there are fluctuations in the shaft length. Figure (c) shows the precautions when using stripper bolts of the outer thread type. If the chamfering of the tapped part is too large, as is shown in the figure, the end part of the shaft gets into the chamfering part. Further, care should be taken because breakage of the stripper bolt may be caused if the tap for attaching the stripper bolt has been machined with an inclination.

Fig. 2

(3) Special method of use

Depending on the die, sometimes there is no space at the top and at the bottom, but a need for making the amount of stripper movement large. In such situations, the usual method of using stripper bolts is not good. Fig. 3 shows an example of obtaining a long stroke in a narrow space by using in combination with a stroke extending retainer.

Fig. 3

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