#109 Terminology and Surroundings (3) Stripper, Blank Holder, Pressure Pad
(1) Stripper (Fig. 1)
In press forming, a stripper is a part used for stripping off the material that has become adhered to the punch. This is also called by other names such as "scrap remover", "brush", etc.
The method of using a stripper can be by fixing to the die plate a "fixed stripper", or "semi-fixed stripper" which is movable although it has been fixed to the die plate. Their only purpose is to strip off the material that has become adhered to the punch.
Further, there is the "movable stripper" which is attached on the punch side and is movable. This type of stripper is also made to have the action of pressing the material to the die plate. The purpose is to prevent deformation of the material used for forming.
(2) Blank holder (Fig. 2)
A blank holder is a part that is used in dies for drawing. It is used for pressing the material and for preventing the generation of wrinkles. The blank holder for the first drawing from a blank has the same structure as a movable stripper. The purpose of pressing the material and preventing the generation of wrinkles is the same as the purpose of stripping of the material that has become adhered to the punch.
(3) Pressure pad (Fig. 3)
A pressure pad presses against the material during L bending or U bending, and is used for preventing the springing back of the material and the sliding of the material during forming. There is also the purpose of stripping off the material from the punch after forming.
As can be understood from the respective figures, the structures are all the same. They are called by different names only depending on their purpose of use. The name indicates what is expected of the part.


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- #164 Problems in Punching and their Countermeasures (3) Bending and Twisting of Narrow Punched Parts
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