1. Forging processing
High-carbon, high-alloy steels, such as Cr12MoV, W18Cr4V, etc., are widely used in the manufacture of molds. However, such steels have various defects such as segregation of components, uneven carbides, and uneven structure. To make molds from high-carbon and high-alloy steels, a reasonable forging process must be used to form the module blanks. On the one hand, the steel can reach the size and specifications of the module blanks, and on the one hand, the microstructure and properties of the steel can be improved. In addition, the high-carbon, high-alloy die steel has poor thermal conductivity, the heating rate cannot be too fast, and the heating should be uniform. In the forging temperature range, a reasonable forging ratio should be adopted.

2, cutting processing

The cutting of the mold should strictly guarantee the radius of the fillet at the transition of the dimension, and the intersection of the arc and the straight line should be smooth. If the cutting quality of the mold is poor, the mold loss may be caused in the following three aspects: 1) The sharp corner or the radius of the fillet is too small due to improper cutting, which may cause serious stress concentration during the working of the mold. . 2) The surface after cutting is too rough, there may be defects such as tool marks, cracks, and slits. They are both stress concentration points and the origin of cracks, fatigue cracks or thermal fatigue cracks. 3) The cutting process fails to completely and evenly remove the decarburized layer generated during the rolling or forging of the mold. It is possible to produce an uneven hardened layer during the heat treatment of the mold, resulting in a decrease in wear resistance.

3, grinding processing

After quenching and tempering, the mold is generally ground to reduce the surface roughness. Due to excessive grinding speed, excessive grinding wheel size or poor cooling conditions, the surface of the mold is locally overheated, causing local microstructure changes, or causing surface softening, hardness reduction, or high residual tensile stress. Such phenomena will reduce the service life of the mold, select appropriate grinding process parameters to reduce local heat generation, and perform stress relief treatment under possible conditions after grinding to effectively prevent the occurrence of grinding cracks. There are many measures to prevent overheating and grinding cracks. For example, use coarse grinding wheels with strong cutting force or grinding wheels with poor adhesion to reduce the grinding feed of the mold; use suitable coolant; grinding After 250 to 300 ° C tempering eliminates grinding stress and the like.

4, EDM

When the mold is processed by the electric spark process, the current density in the discharge zone is very large, and a large amount of heat is generated. The temperature of the processed region of the mold is as high as 10000 ° C. Due to the high temperature, the metallographic structure of the heat affected zone is bound to change, and the surface of the mold is changed. Melting occurs due to high temperature, then quenching, solidifying quickly, forming a re-solidified layer. It can be seen under the microscope that the re-solidified layer is white and bright, and there are many micro-cracks inside. In order to extend the life of the mold, the following measures can be taken: adjusting the EDM parameters by electrolysis or mechanical grinding to grind the surface after EDM, removing the white layer in the abnormal layer, especially to remove microcracks. After EDM A low temperature tempering is arranged to stabilize the anomalous layer and prevent microcrack propagation.