What are the main components of mold design? (2)

5. Design of the die
(1). Design of punching die
The main items that should be considered in the shape design of the punching die are: A. The life of the die and the shape of the escape angle, B. The cutting angle of the die, and C. The division of the die.
(A). Die life and shape of escape angle: This design is a very important matter. If the design is incorrect, it will cause damage to the punch, blockage or floating of punching chips, and occurrence of burrs and other poor stamping processes.
(B) Shearing angle of the concave die: In order to reduce the punching force when the shape is punched, the concave die can be designed with a shearing angle. When the shearing angle is large, the reduction of the punching force will also be large, but it is easy to cause inflection and deformation of the product. .
(C). Divide of the concave die: The concave die must be subjected to finishing such as forming and grinding. Because of its concave shape, the grinding tool is not easy to enter, so it must be divided.
(2). Design of Bending Die
In the design of the die for bending, in order to prevent the occurrence of springback and excessive bending, the shape of the die for U-shaped bending is a combination of double R and straight line (slope of 30 degrees), and it is best to approximate R shape. The shape of the R part should be polished after forming grinding or NC electrical discharge machining.
(3). Design of drawing die
The shape and shape of the corner and escape angle of the drawing die are very important design matters. The shape and characteristics of the corner and the escape angle are as follows: When the R angle of the drawing die is large, the drawing process is easier, but the surface of the drawn product will also be drawn. The phenomenon of wrinkling occurs, and the thickness of the side wall of the extension product is greater than the thickness of the plate. For the occasions where it is difficult to extend thick plate parts and ejection, the R value of the die should be small, which is about 1-2 times the thickness of the plate. For the purpose of burning, destruction of lubricating oil film and reducing ejection force, there should be an escape part (stage shape or push-pull shape) design under the straight section. Especially in the case of shrinkage processing, it is necessary to minimize this straight section.
6. Countermeasures against side pressure of the punch
It is the best ideal state that the punch bears an equal load on the left and right sides during stamping processing (that is, the lateral pressure is zero). When the punch bears lateral pressure, the upper die and the lower die will be displaced in the lateral direction, resulting in the part of the die gap. It becomes larger or smaller (uneven gap) and cannot get good precision stamping. The countermeasures for the lateral pressure of the punch are as follows: (A). Change the processing direction, (B). The products processed on one side (punching, bending, stretching, etc.) should be arranged in two rows, (C). Punching The head or the die is equipped with a side pressure stopper, and the side of the cutting edge is provided with a guide part (especially for cutting and breaking processing).
7. Design of the back pressure plate
The main working parts (punch, pressure plate, die) will bear the surface pressure in the back of stamping process. When the punching pressure is higher than the surface pressure, a back pressure plate (especially the back of the punch and die sleeve) should be used. Back pressure plate There are two forms of use: partial use and full use.