According to different stamping materials, the design of stamping die is different, which is basically through multi-step stamping to complete a product or semi-finished work. Different steps require different shapes and specifications of cemented carbide punches, which is designed to match the special punches of the stamping die for customized production. According to different shapes and uses, the special-shaped carbide punching needles can be divided into:
Guide punch is also called guide punch for short. According to the needs of the press, there can be various shapes, such as type A, type B, type Hb, type TAPP, type TP, etc.
It’s also called mother and child punch. It’s called mother and child punch for short. There is a small protrusion at the top of the punch. I don’t know the origin of the name, maybe it’s because of the protrusion at the top of the punch. The letter punching needle can be divided into standard A-type JS * * type and other models.
There are teeth drawing punch, inspection tip, hexagonal punch, elliptical punch, forming punch, fan punch, special punch, high-speed steel punch, tungsten steel punch, etc.
The key point of cemented carbide punching pin customization is to design the accuracy and consistency of products, and its physical parameters are as follows:
1. CO content: 10% – 20%. 2. Density g / cm3: 14.0-14.5.
3. Hardness: 87-92.0hra. 4. Grain size: 0.6-1.2um.
5. Bending strength: 4000mpa. 6. Elastic modulus GPA: 490.
7, coefficient of thermal expansion 10-6 / 0C: 5.4. 8. The external dimension specification of cemented carbide punch is customized according to the drawing, and the accuracy requirement is ± 0.002.
The precision of carbide punching needle used in high-precision die matching is very high, and the consistency of products is also required. Every punching needle in batch production must be strictly in accordance with the requirements of dimensional accuracy tolerance, so as to maximize the service life of die. The consistency of products is a key factor for the use of carbide punching pins as a complete set of precision dies, which will directly affect the service life of dies and the dimensional accuracy of products.
The stamping die work is continuous operation, so the service life requirement of the hedging needle becomes the focus. According to the material and thickness of the stamping, different alloy materials should be selected for the hard alloy punching needle. Generally, the thicker the product is, the lower the hardness and the better the toughness of the hard alloy should be selected. The harder the material is, the harder the cemented carbide is, the lower the hardness is. This can effectively avoid the punching needle being missed. For the punching of thin plates, or those with low hardness, the carbide punching needle can be used with higher hardness for hole processing of this product, so as to improve the service life of the punching needle.
In addition to the selection of cemented carbide materials, one of the important factors affecting the quality and service life of the punching needle is whether the gap between the cold dies is even. In the process of hard alloy punching pin assembly, it is necessary to ensure that the gap between the convex die and the concave die is the same. In order to ensure that the gap between the punch and the die is even, the position of one piece (punch or die) must be determined first according to the drawing requirements, and then the accurate position of the other piece can be determined by aligning the gap based on this piece. Some stamping dies are equipped with many hard alloy punches at one time, which requires the scientificity and rationality of die design.
There are several ways to control the gap between punch and die to be uniform when assembling punching pin:
1. Light transmission method: place and install the upper mold and the lower mold, irradiate with light or flashlight, and observe the light transmission in the blanking hole of the lower mold.
2. Gasket method: for copper or paper pieces with uniform thickness around the edge of the die and thickness equal to the unilateral gap between the punch and the die, insert the punch into the corresponding hole of the die, observe the tightness between the punch and the gasket, and gently tap the fixing plate with a hammer to make the tightness between the punch and the gasket consistent. After proper adjustment, fasten the upper die.
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