The Research Of Thesmall Parts Heat Treatment Process

The paper is about the needle,the key part of the weaving machion,which has high quality in both performance and precision. And with the increasing of the fast devolopment of needle market, the need of the high-technology in needle market is highly improved. But compared to the forgin needle, we have several defects as follow:lacking of the process sheet, lacking of uniformity in hardness and transformation. This paper is about to introduce the heat process in both transformation and combination property.According to the real condition in company, the needle not only has some hardness strength and resistence of wearing, but also has some sort of elasticity and toughness, to keep away the breakage and transformation. The most impotant thing is that the transformation after the heat treatment cannot be to observed, otherwise the part cannot reach the usage of the real condition. The paper’s aim is to find a reasonable scheme that at the premise not reducing the preformance to increasing the resistence of transformation. As to SK5steel, three designs can be done:first using the fixture; second, change the scheme of heat treatmentm using bainite austemperingreplacing austempering. third, martensite austemperingreplacingaustempering.firstly, at the basis of flexo stove, austemperingexperment can be done to the needles, with the change of temperature and thermo time, the influence of austemperingand tempering is got, which finally confirmation the temperature at800C, backfire temperature at200C. Another experiment is about the needles with fixture and the needles without fixture, the result showed that the ones with fixture’s transformation in both side is less than0.01mm, but the hardness canbe a bit low.Secondly, in changing the heat treatment which using bainite austemperingto search of the proper treatment. The result showed that using the bainite austemperingcan have low hardness than the formal one, but have less transformation at the same time. At the heating range among240C to320C, can get bainite.With the increasing of temperature, the hardness of the needle firstly increased than decreased, and at the temperature260C is the highest. At the same temperature, with the increasing of the time, the hardness of the needle is decreasing, and the result find out1Omin is the best.And at the same time the paper find out using the martensite austemperingreplacing the formal one. The preformance showed that they have little different in hardness and elasticity.