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| Published：2011.07.27 News Sources： Views： | |||
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As we all know, mold during heat treatment, especially in the quenching process, due to the various parts of the mold cross-section of inconsistent heating and cooling rate caused by temperature difference, combined with the unequal nature of organizational changes and other reasons, making all parts of the mold cross-section volume expansion and contraction uneven, uneven organizational change, which led to "organizational stress" and the temperature difference between inside and outside the mold caused by thermal stress. Mold heat treatment process of deformation is the major shortcomings of the mold, one of a number of sophisticated mold, often due to heat deformation and scrapped, so sophisticated control deformation of the mold has been a key issue in the heat production. When the internal stress exceeds the yield limit mold, can cause deformation of the mold. Therefore, the reduction and control of sophisticated mold deformation heat treatment but the majority of workers in an important research topic. This paper on the status of sophisticated mold deformation, deformation study of the causes, to reduce and control the precision of mold deformation complex of measures to improve product quality and service life of the mold. First, the mold material factors and preventive measures: 1. Mold material selection: (1) Machinery Plant selection and heat treatment from simple considerations, choose T10A steel section size disparities, requires a smaller deformation after quenching the more complex molds, hardness 56-60HRC. Hardness after heat treatment mold meet the technical requirements, but the larger mold deformation, can not be used, resulting in mold scrapped. Later the plant micro-deformation of steel Cr12 steel, mold hardness and deformation after heat treatment are in line with requirements. (2) preventive measures: thus create sophisticated, requiring less deformation of the mold, to try to use micro-deformation of steel, such as air quenching steel. 2. Mold material impact: For example, some of the more complex Cr12MoV steel molds, molds with ¢ 60m m hole, heat the mold, some mold appeared oval hole, resulting in mold scrapped. Generally Cr12MoV steel is slightly deformed steel, there should be no greater distortion. We have a serious mold deformation metallographic analysis, tool steel contains a large number of eutectic carbides, and the zonal and massive distribution. (1) oval die (deformation) This is because the causes of die steel in a certain direction was the existence of the uneven distribution of carbide, carbide expansion coefficient than the steel substrate is about 30% smaller organization, it prevents mold heating hole expansion, cooling time and shrink the hole to prevent mold, so mold Kong Fasheng uneven deformation of the mold holes appear oval. (2) Preventive measures: ① in the manufacture of sophisticated mold, to try to choose a smaller tool steel carbide segregation, do not plan cheaper, use less of small steel mills produce steel materials. ② serious segregation of the existence of carbide tool steel forging to make a rational, to break the carbide crystal block, reducing the uneven distribution of carbide grades, eliminating performance anisotropic. ③ on the forging die steel after quenching and tempering heat treatment to be carried out, so get carbide distribution, small and dispersed sorbite tissue, thereby reducing the sophisticated mold deformation after heat treatment. ④ For larger mold or can not be forged, double-thinning solution can be used to make carbide refinement, distribution, rounded edges and corners, then it can achieve the purpose of reducing the deformation of the mold heat treatment |
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