Prevention of heat treatment deformation of mold
The causes of deformation of precision complex moulds are often complex, but we just need to grasp its deformation law, analyze the reasons for its generation, and adopt different methods to prevent the deformation of moulds can be reduced and controlled. Generally speaking, the heat treatment deformation of precise and complex moulds can be prevented by the following methods.
(1) Fair selection of materials. For precision complex mold should choose material good micro-deformation mold steel (such as air hardening steel), the carbide segregation severe mold steel should be fair casting and tempering heat treatment, for larger and can not cast mold steel can be solid solution double refinement heat treatment.
(2)The mold structure design should be fair, the thickness should not be too disparate, the shape should be symmetrical, for the deformation of larger molds to grasp the deformation law, allow for processing allowance, for large, precision complex molds can be used in combination structure.
(3)The precision complex mould should be preheated to eliminate the residual stress generated during the mechanical processing.
(4) Fair selection of heating temperature, control the heating speed, for precision and complex molds can take slow heating, preheating and other balanced heating methods to reduce mold heat treatment deformation.
(5) in the condition of ensuring the hardness of the mold, try to use pre-cooling, graded cooling quenching or warm quenching process.
(6) for precision and complex mold, in the premise of permission, try to use vacuum heating quenching and quenching after the deep cooling treatment.
(7) for some precision and complex mold can use pre-heat treatment, aging heat treatment, tempering nitriding heat treatment to control the accuracy of the mold.
(8) In the repair of mold sand holes, air holes, wear and other defects, the use of cold welding machine and other repair equipment with little thermal impact to avoid the generation of deformation in the repair process. In addition, accurate heat treatment process manipulation (such as plugging holes, tied holes, mechanical fixing, appropriate heating methods, accurate selection of the cooling direction of the mold and the direction of movement in the cooling medium, etc.) and fair tempering heat treatment process is also an effective measure to reduce the deformation of precision and complex molds.