Mold heat treatment is an important process to ensure mold performance, the mold manufacturing accuracy, plastic mold strength, mold working life, mold manufacturing costs have a direct impact.
Die heat treatment is to play the potential of mold materials and improve the use of mold performance. Mold performance must meet: high strength (including high temperature strength, thermal and thermal fatigue resistance) high hardness (wear resistance) and high toughness, and also requires good machinability, including good polishing ) Weldability and corrosion resistance and so on.
Plastic mold heat treatment after the deformation are generally considered to be caused by cooling, which is not correct. Die especially the complex mold, the processing technology is correct or not, the deformation of the mold often has a greater impact on some mold heating process can be clearly seen, the heating speed is faster, often have greater deformation.
(1) causes of deformation
Any metal heated to expand, because the steel in the heating, the same mold, all parts of the uneven temperature (ie, uneven heating) will inevitably cause various parts of the mold expansion inconsistency, resulting in heating due to heating Uneven internal stress. In the steel below the phase transition temperature, uneven heating mainly produces thermal stress, over the phase transition temperature heating uneven, but also produce unequal time-varying tissue, both to produce tissue stress. Therefore, the faster heating rate, the mold surface and the heart of the greater the difference between the temperature, the greater the stress, mold deformation after heat treatment greater.
(2) Preventive measures
Complex molds in the phase transition point below the heating should be slow heating, in general, the mold vacuum heat treatment deformation than salt bath furnace quenching much smaller. Preheating can be used for low alloy steel molds once (550-620 ℃); for high alloy steel molds should be used twice preheating (550-620 ℃ and 800-850 ℃). 【Suzhou Mold Casting】