In the process of heat treatment, the precision plastic injection mold often produces deformation. In order to prevent this kind of problem, as long as we grasp the deformation law, analyze the causes, and adopt different methods to prevent the deformation of the mold, it can be reduced and controlled. In general, the following methods can be adopted to prevent the heat treatment deformation of precision injection mold.
(1) Reasonable selection of materials: the micro deformation die steel with good material should be selected for the precision plastic injection mold, the mold steel with severe carbide segregation should be reasonably cast and carried out, and the large and non-casting mold steel can be treated with solid solution double refinement heat treatment.
(2) The mold structure design should be reasonable, the thickness should not be too different, and the shape should be symmetrical. For the large deformation mold, we should grasp the deformation pattern and reserve the processing allowance. For the large ones, the combined structures of precision injection mold can be adopted.
(3) The precision injection mold should be pre-heat treated to eliminate the residual stress in the process of mechanical processing.
(4) Reasonably select the heating temperature and control the heating speed. For the precision injection mold, slow heating, preheating and other balanced heating methods can be adopted to reduce the heat treatment deformation of the mold.
(5) Under the condition of ensuring the hardness of the mold, the pre-cooling, staged cooling quenching or warm quenching process of the injection mold should be adopted as far as possible.
(6) For precision injection mold, vacuum heating quenching and cryogenic treatment after quenching shall be adopted as far as possible if the premise permits.
(7) The precision of some precision and complicated dies can be controlled by pre-heating treatment, aging heat treatment, quenching, tempering and nitriding heat treatment.
(8) When repairing sand hole, air hole, wear and other defects of mold, cold welding machine and other repair equipment with small heat influence shall be selected to avoid deformation in the repair process.