On 2018-08-08 14:48:54
Vacuum heat treatment process of mould
The advantages of vacuum heat treatment technology in mould processing
The development of heat treatment is accompanied by the development of mechanical manufacturing industry. Mechanical manufacturing puts forward higher requirements for heat treatment, and the heat treatment of mold is the most technical part of heat treatment.
As we all know, die heat treatment is to develop the potential of die material and improve the performance of die. The performance of the die must meet the following requirements: high strength (including high temperature strength, cold and hot fatigue resistance), high hardness (wear resistance) and high toughness, as well as good machinability (including good polishing), weldability and corrosion resistance.
The biggest influence on the life of the die is the design of the die (including the correct choice of materials), the material of the die, the heat treatment of the die, the use and maintenance of the die, etc. If the design of the die is reasonable and the material is high quality, the quality of heat treatment directly determines the service life of the die. At present, both at home and abroad are trying to use more advanced heat treatment means to improve the performance of the mold and extend the service life of the mold. Vacuum heat treatment is one of the most advanced methods in mold heat treatment. Therefore, from the perspective of mold heat treatment, the status of heat treatment processing equipment, heat treatment process, production process control is particularly important. The advanced nature of equipment is the premise to ensure the realization of advanced technology. Vacuum high pressure gas quenching furnace is the most ideal equipment to realize vacuum heat treatment. The vacuum furnace has the effect of non decarburization and non oxidation, with uniform temperature, controllable heating and cooling speed, and can realize different process. Because there is no pollution in the vacuum furnace, it is internationally recognized as "green heat treatment". Now there are 2-20bar vacuum high pressure gas quenching furnace in the world, which can fully meet the requirements of vacuum heat treatment of the mould.
In the process of die heat treatment, the process parameters used also have a crucial impact on the die performance: it includes heating temperature, heating speed, holding time, cooling mode, cooling speed, etc. The correct heat treatment process parameters can ensure the best performance of the die, otherwise, it will produce bad or even serious consequences. Practice shows that good structure can be obtained by correct heat treatment process, and good structure morphology can guarantee excellent mechanical properties. The proper process can effectively control the deformation and cracking of the die during heat treatment. It is found from practice that the difference between the surface temperature and the core temperature (the heating and cooling non-uniformity) is the main factor that causes the die deformation during the process of heating and cooling. (the vacuum furnace has the ability to control the heating speed and cooling speed). Different processing methods can make the mold meet different use conditions and different performance requirements.
From the perspective of the service life of the die, meeting the requirements of hardness is only one aspect of meeting the technical requirements of the die. There are also some performance requirements that are not easy to measure, such as strength and toughness. The quality of the mould can not be completely determined by the hardness index. It is impossible to finally test the service life of the mould by the hardness measurement method. As a special process (i.e. special process), heat treatment can only confirm the reasonable process parameters through process verification and performance experiment, and strictly implement the confirmed process parameters (process control) to ensure the product quality Reliability and stability. A large number of data show that the deformation of cold stamping die processed by vacuum heat treatment is small, and the phenomenon of wire cutting cracking and grinding cracking rarely occurs. The die-casting die adopts advanced technology to reduce the cracking of the die and the phenomenon of sticking the die in use to a certain extent.
All in all, the vacuum high pressure gas quenching process has the advantages of free control of heating and cooling speed. Different process parameters can be compiled to obtain the expected microstructure and properties.