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Wednesday, 05 September 2012 08:32 hiparterhigrade Technology News
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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].

[Fig.1] Method of preparing a compound die structure (example of a compound blanking

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.

 
Thursday, 09 February 2012 08:11 administrator Technology News
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Knowing the forming force necessary for carrying out a press blanking operation (shearing operation) is indispensable for selecting the press machine and for carrying out the die and punch design.

 

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Sunday, 20 November 2011 16:56 administrator Technology News
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In the crank press which is used most widely in press forming, there is the pressing capacity (capacity to apply pressure) which is an indicator of the capacity of the press machine.

Pressing capacity is the maximum pressure that the press machine can generate safely. As shown in Table 1 in the case of a crank press, the pressure generated changes depending on the stroke position of the slide. So the pressing capacity indicates the pressure at a determined position above the bottom dead point. In the example shown in Table 1, it can be seen that a pressure of 980kN (980 kilo Newtons = 100 tons) is being obtained at a position of 5 mm above the bottom dead point.

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Tuesday, 19 July 2011 14:47 administrator Technology News
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There are two types of die heights, that is  die height of the press machine and the die height.

Die height has restrictions related to the height of installing the die.

The primary height of the die is that of the press machine, and the secondary height of the die is of the die.

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Wednesday, 16 February 2011 11:19 administrator Technology News
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A die set is a unit component constituted from a punch holder, a die holder, a guide post, and a guide bush.

Die sets are used for maintaining correct relationship between the top die and the bottom die as shown in Fig. 1. 

If we consider the relationship between the punch and the die when the top die is taken to be a punch and the bottom die is taken to be a die, the relationship between the punch and the die is maintained by being conveyed by the dowel pin (knock pin) to the guide of the die set (see Fig. 1).

 

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