The main reasons for the bursting of the tungsten steel wire drawing die are as follows:
1. The mold material is not good and it is easy to chip in the subsequent processing
2. Heat treatment: deformation caused by improper quenching and tempering process
3. The mold grinding flatness is not enough, resulting in flexural deformation
4. Design process: the strength of the mold is not enough, the knife edge spacing is too close, the mold structure is unreasonable, the number of template blocks is not enough, there is no backing board
5.Improper handling of wire cutting: pulling wire cutting, the gap is wrong, and the corner is not cleaned
6. Selection of punch equipment: punch tonnage, insufficient punching force, and too deep adjustment of the die
7. Unsuccessful stripping: no demagnetization treatment before production, no return pin; there are jammed materials such as broken needles and broken springs during production
8. The blanking is not smooth: there is no leakage of feces when assembling the mold, or rolling to block the feces, and the feet to block the feces
9. Production awareness: laminated sheet stamping, positioning is not in place, no air blow gun is used, and the template has cracks and still continues to produce
Die failure mode
The main forms of die failure are wear failure, deformation failure, fracture failure and gnawing failure.
However, due to different stamping processes and different working conditions, there are many factors that affect the life of the die. The following is a comprehensive analysis of the influencing factors of the die life on the design, manufacture and use of the die, and the corresponding improvement measures are found.
1 Stamping equipment
The accuracy and rigidity of stamping equipment (such as presses) have an extremely important impact on the life of the die. The stamping equipment has high precision and good rigidity, and the life of the die is greatly improved. For example, the material of the complex silicon steel sheet die is Crl2MoV. When used on an ordinary open press, the average regrinding life is 1-3 thousand times, while when used on a new precision press, the die's regrinding life can reach 60,000-120,000 times. Especially for small or no-clearance punches, hard alloy punches and precision punches, presses with high precision and good rigidity must be selected. Otherwise, the life of the mold will be reduced, and the chess tools will be damaged in severe cases.
2 Mold design
(1) The precision of the guide mechanism of the mold. Accurate and reliable guidance has a great impact on reducing the wear of mold working parts and avoiding the damage of convex and concave molds, especially the gapless and small gap blanking dies, compound dies and multi-station progressive dies are more effective. In order to improve the life of the mold, it is necessary to correctly select the guiding form and determine the accuracy of the guiding mechanism according to the nature of the process and the accuracy of the parts. Under normal circumstances, the accuracy of the guide mechanism should be higher than the matching tip of the male and female molds.
(2) The geometric parameters of the cutting edge of the mold (convex and concave mold). The shape, matching clearance and fillet radius of the convex and concave molds not only have a great influence on the forming of the stamping part, but also have a great influence on the wear and life of the mold. For example, the fit gap of the mold directly affects the quality of the blanking parts and the life of the mold.
For higher precision requirements, a smaller gap value should be selected; otherwise, the gap can be appropriately increased to improve the life of the mold.
3 Stamping process
(1) The raw materials of stamping parts.
In actual production, due to excessive thickness tolerances of the raw materials of external pressure parts, fluctuations in material properties, poor surface quality (such as rust) or dirty (such as oil stains), etc., it will cause increased wear of mold working parts and easy chipping. as a result of. For this reason, attention should be paid to: ①Use materials with good stamping processability as much as possible to reduce stamping deformation force; ②Strictly check the grade, thickness and surface quality of the raw materials before stamping, and wipe the raw materials clean, and clean the surface if necessary Oxide and rust; ③According to the stamping process and the types of raw materials, softening treatment and surface treatment can be arranged when necessary, and suitable lubricants and lubricating processes can be selected.
(2) Layout and edging.
Unreasonable reciprocating feeding layout method and too small overlap value will often cause rapid wear of the mold or damage to the convex and concave molds. Therefore, while considering the improvement of material judgment and utilization, it is necessary to reasonably select the layout method and the edge value according to the processing batch, quality requirements and mold matching gap of the parts to improve the life of the mold.
4 Mold material
The influence of mold material on mold life is a comprehensive reflection of material types, chemical composition, organizational structure, hardness and metallurgical quality. Die life of different materials is often different. For this reason, two basic requirements are put forward for the material of the working parts of the die: ①The material's performance should have high hardness (58-64HRC) and high strength, and have high wear resistance and sufficient toughness, heat treatment deformation is small, and there is a certain degree The thermal hardness; ②The process performance is good. The processing and manufacturing process of die working parts is generally more complicated. Therefore, it must have adaptability to various processing techniques, such as forgeability, machinability, hardenability, hardenability, quenching crack sensitivity and grinding workability. Usually according to the material characteristics of the stamping parts, production batch, precision requirements, etc., the mold material with excellent performance is selected, while taking into account its manufacturability and economy
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