1. Universal cryogenic treatment process of special cryogenic freezer for spindle cold assembly
Reduce the temperature to – 150 ℃ at the rate of per minute. The cooling time can be set, then keep warm, and then increase to rich temperature or higher at the rate of per minute reduction.
2. Significance of each stage of special cryogenic freezer for cold assembly of main shaft
(1) Cooling stage
The purpose of cooling the special cryogenic freezer for cold assembly of the main shaft is to completely eliminate the residual stress. Because in the process of quenching and tempering, the special deep low temperature freezer for cold assembly of main shaft produces residual stress. In the process of transformation from residual martensite to martensite, the volume expansion will also increase the residual stress. Only slow cooling can offset the increase of residual stress and completely eliminate the residual stress. The residual stress in the matrix is generally ignored, but it is the residual stress in the matrix that causes the product to crack and other defects. However, rapid cooling will increase the residual stress.
(2) Insulation stage
The purpose of the special cryogenic freezer for cold assembly of the main shaft is to make the residual austenite in the matrix transform into martensite as much as possible, and to produce more carbide grains as much as possible, because the transformation process from residual austenite to martensite is a spring process, and the length of the heat preservation time will affect the amount of the transformation of the martensite. At the same time, the high and low life after the deep heat preservation is mainly the length of the heat preservation time Generally speaking, the performance of 2-4 hours of heat preservation has been improved, but if high-quality products need to use more than 24 hours of heat preservation, the multiple of toxic life is directly related to the length of heat preservation time.
(3) Heating stage
The special deep and low temperature freezer for cold assembly of main shaft generally rises to room temperature. If the special purpose of the parts is considered, such as high working temperature, it can rise to slowly again. From the mechanism of deep order, it can be seen that the above process curve has little relationship with the material and size of the material, but the effect of the treatment is different due to the material factors. Almost all foreign tools, moulds, cutters, and quantities The cutting tools are all processed by this process.