Stamping die is the main process equipment of stamping, and it is a key die in industrial production. There are many factors affecting the service life of stamping dies, one of which is the failure of stamping dies. The main forms are wear failure, deformation failure, fracture failure and gnawing failure. Now we will make a specific introduction to these, hoping that you can understand them and make corresponding improvement measures.

1 Stamping equipment

The precision and rigidity of stamping equipment (such as press) are very important to the life of stamping die. The stamping equipment has high precision, good rigidity and greatly improves the service life of the stamping die. For example, the die material of complex silicon steel sheet is Cr12MoV, which is used on an ordinary open press and has an average regrinding life of 1-3 million times. However, when used on a new precision press, the regrinding life of the die can reach 60 to 120 thousand times. In particular, the press with high precision and good rigidity must be selected for small clearance or no clearance die, cemented carbide die and precision die, otherwise, the life of the die will be reduced, and even the chess pieces will be damaged in serious cases.

2. Stamping die design

(1) The precision of the guide mechanism of the die. Accurate and reliable guidance has a great impact on reducing the wear of working parts of the die and avoiding the gnawing of male and female dies, especially the blanking die with no clearance and small clearance, compound die and multi station progressive die. In order to improve the service life of the die, it is necessary to correctly select the guide form and determine the precision of the guide mechanism according to the requirements of the process nature and the part precision. In general, the precision of the guide mechanism should be higher than the fit taper of the convex and concave dies.

(2) Geometric parameters of die (male and female die) cutting edge. The shape, fit clearance and fillet radius of male and female dies have great influence not only on the forming of stamping parts, but also on the wear and life of dies. For example, the fit clearance of the die directly affects the quality of the blanking part and the life of the die. For those with high accuracy requirements, smaller clearance values should be selected; On the contrary, the clearance can be appropriately increased to improve the service life of the die.

3 Stamping process

(1) Raw materials for stamping parts.

In actual production, because the thickness tolerance of the raw materials of the external pressure parts is out of tolerance, the material performance fluctuates, the surface quality is poor (such as rust) or not clean (such as oil stain), etc., it will cause the adverse consequences such as increased wear of the working parts of the mold, easy to break the blade, etc.

To this end, it should be noted that:

① The raw materials with good stamping process shall be used as far as possible to reduce the stamping deformation force;

② Before stamping, the brand, thickness and surface quality of raw materials shall be strictly checked, and the raw materials shall be wiped clean. If necessary, the surface oxide and rust shall be removed;

③ Softening treatment and surface treatment can be arranged when necessary, and appropriate lubricants and lubrication processes can be selected according to the stamping process and the type of raw materials.

(2) Layout and overlap.

Unreasonable reciprocating feeding layout method and too small overlap value often cause sharp wear of the die or gnawing of the convex and concave dies. Therefore, while considering improving the utilization of materials, we must reasonably select the layout method and overlap value according to the processing batch, quality requirements and die fit clearance of parts to improve the life of the die.

4 Stamping die materials

The influence of die material on die life is a comprehensive reflection of material type, chemical composition, microstructure, hardness and metallurgical quality. The service life of dies made of different materials is often different.

For this reason, two basic requirements are put forward for the materials of working parts of the die:

① The material shall have high hardness (58~64HRC), high strength, high wear resistance and sufficient toughness, small heat treatment deformation and certain thermal hardness;

② The processing property is good. The processing and manufacturing process of working parts of stamping die is generally complicated. Therefore, it must be adaptable to various machining processes, such as forgeability, machinability, hardenability, hardenability, quenching crack sensitivity and grinding machinability. Generally, mold materials with excellent performance are selected according to the material characteristics, production batch, accuracy requirements, etc. of the stamping parts, taking into account its processing and economy.

Toolox series material is a new kind of pre hardened tool steel with high toughness, high wear resistance and basically no internal stress Processing stability is particularly good. Compared with the corresponding materials under the same conditions, the processing efficiency has increased by about 20%. It also has very high purity, very fine grain size, very little S and P content, and little carbide precipitation, which is very uniform Due to the special composition design, Toolox series materials have very excellent surface treatment performance. The surface hardness of Toolox44 after nitriding can reach more than HRC65, the surface hardness of Toolox40 can reach more than HRC62, and the surface hardness of Toolox33 can reach more than HRC58, with a depth of up to 1.8mm. Therefore, TOOLOX series materials have special advantages in the application of stamping dies.