A, some hardware mold material selection, and the material of steel is very good, often because of the mold structure design is unreasonable, such as thin edge, Angle, the steps of the groove, mutation and thickness disparity, cause mould heat treatment after deformation.
Throughout the cause of the deformation due to the mold thickness or shrill rounded corners, so during quenching cause thermal stress and organization stress between each part of the mould is different, resulting in the different parts of the volume expansion is different, make the mold after quenching distortion.
Precautions when designing hardware die mould, in meet the need of actual production situation, should try to reduce the mold thickness disparity and asymmetric structure, in addition, the thickness of the mould, as far as possible, by adopting the structure design of smooth transition.
According to the deformation law of mould machining allowance reserve, not because the mold after quenching deformation and make the mold scrapped.
Very complicated shape mould, in order to make uniform when the quenching cooling, composite structure can be used.
Residual stress in the process of machining deformation reasons and after quenching stress superposition, increases the mold heat treatment after deformation.
Preventive measures (
After rough machining, half should be done before finishing a stress relieving, namely,
H furnace cooling below 500 ℃ from empty cold, also can be used 400 ℃ & times;
H to deal with stress.
Reduce the quenching temperature, reduce the residual stress after quenching.
The quenching oil 170 oc oil air cooling (
The isothermal quenching process can reduce the quenching residual stress.
After adopting these measures can make the mould quenching residual stress reduction, mold deformation is small.