During the heat treatment process, precision molds often undergo deformation. To prevent this negative phenomenon, we only need to grasp its deformation pattern, analyze its causes, and use different methods to prevent mold deformation, which can be reduced and controlled. Generally speaking, the following methods can be taken to prevent heat treatment deformation of precision and complex molds.
(1) Fair selection of materials. For precision and complex molds, micro deformation mold steel with good materials should be selected (such as air quenched steel). For mold steel with severe carbide segregation, fair casting and quenching and tempering heat treatment should be carried out. For larger and non castable mold steel, solid solution double refining heat treatment can be carried out.
(2) The design of the mold structure should be fair, with no significant difference in thickness and symmetrical appearance. For molds with large deformation, the deformation pattern should be grasped and machining allowance should be reserved. For large, precision and complex molds, a combination structure can be used.
(3) Precision and complex molds require pre heat treatment to eliminate residual stresses generated during mechanical processing.
(4) Reasonably choose the heating temperature and control the heating speed. For precision and complex molds, slow heating, preheating, and other balanced heating methods can be adopted to reduce mold heat treatment deformation.
(5) Under the condition of ensuring the hardness of the mold, try to use pre cooling, graded cooling and quenching, or warm quenching processes.
(6) For precision and complex molds, if possible, vacuum heating quenching and deep cooling treatment after quenching should be used as much as possible.
(7) For some precision and complex molds, pre heat treatment, aging heat treatment, and quenching and tempering nitriding heat treatment can be used to control the accuracy of the mold.
(8) When repairing defects such as sand holes, air holes, and wear in the mold, use repair equipment with minimal heat impact such as a cold welding machine to avoid deformation during the repair process.
There are many methods for heat treatment process operation, including plugging holes, binding holes, mechanical fixation, appropriate heating methods, accurate selection of the cooling direction of the mold and the direction of movement in the cooling medium, etc. A reasonable tempering heat treatment process is also an effective measure to reduce the deformation of precision and complex molds.
