Mold, especially complex mold, whether the processing technology is correct or not often has a greater impact on the deformation of the mold. Compared with some mold heating technology, it can be clearly seen that the heating speed is faster, often has a greater deformation.
1. Effect of heating speed: the deformation of die after heat treatment is generally considered to be caused by cooling, which is not correct. Mold, especially complex mold, whether the processing technology is correct or not often has a greater impact on the deformation of the mold. Compared with some mold heating technology, it can be clearly seen that the heating speed is faster, often has a greater deformation.
(1) Deformation cause: any metal will expand when heated. Because the temperature of each part in the same mold is uneven (i.e. uneven heating) when the steel is heated, the expansion of each part in the mold will be inconsistent, thus forming the internal stress of uneven heating. At the temperature below the transformation point of the steel, the uneven heating mainly produces thermal stress. If the temperature is higher than the transformation temperature, the uneven heating will also produce the unevenness of the structure transformation, which not only produces the structure stress. Therefore, the faster the heating speed, the greater the temperature difference between the die surface and the core, the greater the stress, and the greater the deformation of the die after heat treatment.
(2) Preventive measures: the complex mould should be heated slowly under the phase transformation point. Generally speaking, the deformation of mould after vacuum heat treatment is much smaller than that of salt bath furnace. ‚ preheating is used, one-time preheating (550-620 ° C) can be used for low alloy steel mold, and two-time preheating (550-620 ° C and 800-850 ° C) can be used for high alloy diamond mold.
On 2018-08-08 11:45:46
