#008 Method of Preparing Compound Die Structures
The structure for compound work such as compound blanking or blanking and drawing, etc., is made by combining the basic die structures. In such work, the outer shape (the blank) is prepared, and then additional work is made on it (such as hole punching, or drawing (extruding)).
In general, very often during such work the blank is punched upwards and the additional hole punching, etc. is done downwards. The basic die structures that permit such work are selected respectively and combined thereby creating a compound die structure.
An example of a compound die is explained below. See [Fig. 1].
In compound press work, the die carries out external shape punching and hole punching simultaneously. This is used because of its good aspects such as a good positional relationship between the external shape and the hole, even good flatness of the product, and that the direction of burrs is the same in the external shape and the hole. Apart from this, there is also the advantage that the process can be shortened. However, since there is the disadvantage that, since the product enters the die (the top die), problems in taking out the product can easily occur.
The external shape forming work in [Fig. 1] uses a reverse placement variable stripper type structure and the product is removed upwards. Hole punching is done as usual downwards using the forward placement variable stripper type structure. Because of this relationship, the problem of processing the scrap in hole punching will not be there. These two types of dies are combined into one unified structure. During such unification, the parts that are not common are left as they are. Two of each of the parts that interfere with each other, the external shape blanking punch, the hole punching die, the stripper, and the knock out are combined together and made into single parts. Such parts are called compound parts. The compound die structure is completed because of using these parts.
When interfering parts are unified at the time of carrying out compound work, a judgment should be made as to whether the shape is suitable as a part of the die and as to whether there is any problem in terms of the strength, and the compound die is realized if there is no problem.
Since compound blanking or compound drawing or extrusion are used very frequently, even their structures are found in reference documents and they are used in a manner similar to ordinary dies, and hence these types of structures are used. Even compound dies for hitherto unknown compound works can be prepared using the procedure as described here.
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