In the process of heat treatment, Shandong mold often produces deformation. In order to prevent this bad phenomenon, as long as we grasp its deformation law, analyze its causes, and adopt different methods to prevent mold deformation, it can be reduced and controlled. Generally speaking, the following methods can be used to prevent the heat treatment deformation of the precision complex mold.
(1) Fair selection. For the precision complex die, the micro deformation die steel with good material (such as air quenched steel) should be selected. For the die steel with severe carbide segregation, the reasonable casting should be carried out. For the larger and non casting die steel, the solid solution double refinement heat treatment can be carried out.
(2) The mold structure design should be fair, the thickness should not be too wide, the shape should be symmetrical, for the large deformation mold, the deformation law should be grasped, and the machining allowance should be reserved. For the large, precise and complex mold, the combined structure can be used.
(3) In order to eliminate the residual stress in the process of machining, heat treatment should be carried out in advance for the precision complex die.
(4) Reasonable selection of heating temperature, control of heating speed, for precision complex mold can take slow heating, preheating and other balanced heating method to reduce the mold heat treatment deformation.
(5) Under the condition of ensuring the hardness of the die, pre cooling, step cooling quenching or warm quenching process should be adopted as far as possible.
(6) As far as possible, vacuum heating quenching and cryogenic treatment after quenching should be used for precision and complex molds.
(7) For some precise and complicated dies, pre heat treatment, aging heat treatment and quenching and tempering nitriding heat treatment can be used to control the accuracy of the dies.
(8) When repairing mold defects such as sand hole, air hole and wear, cold welding machine and other repair equipment with small heat effect should be selected to avoid deformation in the repair process.
There are many methods of heat treatment process operation, including plugging, binding, mechanical fixation, appropriate heating method, accurate selection of cooling direction and movement direction in the cooling medium of the mold, etc. reasonable tempering heat treatment process is also an effective measure to reduce the deformation of precision complex mold.