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机器零件中,有许多通用零件如轴、轴套、螺帽等的链槽、小孔、螺纹等都有精度要求,这些部位在淬火后通常会有不同程度的变形。补救的办法,有的采用放磨,但加工很繁重;有的不能放磨,则会大批报废。因此,一般都要求热处理的变形,尤其是形状变形,尽可能减少到最低程度。此外,这些零件多半用中碳结构钢制造,在截面厚薄不均的地方又容易产生开裂。我厂针对这些问题,试验了几种淬火工艺——熔盐浴分级淬火、预冷延迟淬火和三液淬火法。基本上解决了上述零件的变形和开裂。大家知道,引起淬火开裂变形的主要原因是内应力,产生内应力的主要因素如下:(1)热应力——同一截面上由于温度高低不同,产生比容(单位重量的体积大小)不同。特别是在淬火
Machine parts, there are many common parts such as shafts, bushings, nuts and other chain slots, holes, threads and so have precision requirements, these parts will usually have different degrees of deformation after quenching. Remedy, and some put put mill, but processing is very heavy; some can not put mill, it will scrap a large number. Therefore, the heat treatment is generally required deformation, especially the shape deformation, as far as possible to minimize. In addition, most of these parts are made of medium-carbon structural steel, which is prone to cracking at areas of uneven thickness. I plant for these problems, tested several quenching process - molten salt bath classification quenching, pre-cooling delayed quenching and three-liquid quenching method. Basically solve the above parts deformation and cracking. As we all know, the main reason causing the quenching and cracking deformation is internal stress. The main factors that generate internal stress are as follows: (1) Thermal stress - The specific volume (volume per unit weight) is different due to different temperature in the same section. Especially in quenching