Large diameter thin-walled type ring gear carburized common normal size change rule

Large diameter thin-walled type ring gear carburizing change rule for 2019 - common normal size 10 - 18 Hu Donghui ( Hangzhou advance gearbox group co. , LTD. ) Abstract: for the large diameter thin-walled type gear ring, after carburizing and hardening heat treatment deformation is crucial to the quality control index. By carburizing heat treatment before and after the gear measuring common normal size, have mastered this type before and after heat-treatment roughly common normal size change trend, solves the heat-treatment reserve hob grinding such problems of production and service. Key words: gear common normal; Size measurement; Thin wall type; Large diameter; Change rule; Carburizing. Gear ring; Need because of production quality control index, heat treatment plant was gradually introduced to deal with a large diameter gear ring of carburizing heat treatment equipment. Because most of these parts are key-module, size and so on is strict, so the process of carburizing and hardening heat treatment, to control the change of the size of the parts is very important. At the same time, this type parts often layer depth is deeper, under the condition of the parts shape thin, very easy to cause deformation. For service production, better solution after carburizing parts size requirements, so for this type of parts deformation on common normal after carburizing process. 1. Heat treatment process and components of the data using four different diameter of gear ring part, through the different craft of carburizing and hardening, the contrast before and after heat treatment of gear, the changes of common normal to measure the roughly the size of parts. （ 1) Test technology and equipment due to large parts, use & phi; 2500毫米× 2000 mm love association Lin well type carburizing furnace, the paperback parts, gasket, in addition to the teeth of the rest of the product evenly anti-seepage agents, and USES the heat treatment process is shown in figure 1. Figure 1 heat treatment process curve ( 2) Data analysis diagram 2 ~ 5 to participate in the test parts, table 1 for the specific data and the process of corresponding parts. For four different parts, through carburizing and hardening, measuring common normal size after heat treatment, compared to before the heat treatment of common normal size, specific data as shown in table 2. According to the W - after heat W hob = after heat treatment of the common normal up quantity is calculated for each the size of the ring gear changes ( See table 3 and figure 6) Can be found for this type parts deformation is basic in 0. More than 5 mm, and even individual more than 0. 8mm。 For individual parts because of the wall is more thin, such as gear ring gear ring 4, common normal changes from 0. 46 ~ 0. 72 mm between, make the whole part of the common normal changed a lot. 2. Deformation cause analysis parts while using two kinds of heat treatment process, but part deformation trend is consistent, all get a big zero. 5 to 0. 8mm。 Parts after heat treatment, thermal stress and organization stress and thermal stress and organization stress will make quenching workpiece shape change ( Shape distortion) 。 Parts in terms of the thermal stress, while narrow, but at the same time, in the process of cooling, organization change, namely the austenite to martensite transformation process, specific volume larger ( Martensite volume is larger than austenitic) Increased diameter size, thus making the parts. In the thermal stress, the surface and center cooling speed, temperature difference. When surface quenching, shrinkage smaller; When the surface cools, the core cooling only, the volume is not free, so that the parts after heat bilges cold shrink, volume increase. This volume increasing cooling rate, material composition and heat treatment process, when cooling velocity increases, the higher the carbon content and alloy parts composition is higher, the volume change, the more obvious. In addition, affected by other factors, local uneven, cause warping, at the same tooth taper formation, warp in the plane of the parts. 3. Epilogue ( 1) Heat treatment of thermal stress and organization stress is inevitable, but it can reasonable use of deformation, the cold working roll teeth, appropriate decrease grinding, make up for the heat treatment higher quantity. （ 2) This type parts of common normal rise in 0. 5 to 0. 8mm。 Source: the metal processing ( Hot working) 19, 2015