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有些环状凹模,使用到模口变钝或磨损,间隙增大,应该报废。对这种已报废的模具, 我们采用适当的热加工使之收缩后型腔(孔径)减小,获得所需要的磨削量,经重新淬火磨削返修,钢材得到了充分利用。返修收缩工艺是把零件加热至A_(ct)以下一定温度,按淬火加热保温时间上限保温一段时间,然后在水中快速冷却至室温。冷却产生的热应力使内径收缩,随后工件进行一次去应力高温回火。在收缩加热和高温回火时,应注意防止氧化脱碳,应在盐浴炉或充保护气氛的箱式电炉中加热。
Some ring-shaped die, the die used to blunt or wear, the gap increases, it should be scrapped. For such scrapped molds, we reduce the cavity (aperture) after shrinking by appropriate thermal processing, obtain the required amount of grinding, and re-quench and rework the steel to take full advantage of it. Rework shrinkage process is to heat the part to A_ (ct) below a certain temperature, quenching and holding the upper limit of incubation time for a long time, and then quickly cooled to room temperature in water. The thermal stress generated by the cooling shrinks the inner diameter, followed by a stress relief tempering of the workpiece. In shrinkage heating and high temperature tempering, care should be taken to prevent oxidative decarburization and should be heated in a salt bath or a box-type electric furnace under a protective atmosphere.