Hunan Railway Vocational and Technical College (Zhuzhou 412001) Peng Dingjiang Ying Chen Yuezhong 0 Introduction 1 The original processing technology gearbox is one of the important components of mechanical transmission, consisting of transmission shaft, gear and reduction gear. The function of the reduction box is to ensure the running accuracy of the gear, to store and provide lubrication and cooling oil during the operation of the gear, and to prevent dust from entering. This requires high precision and strength of the reduction gearbox, and at the same time ensures good fit and good sealing with the motor shaft and the wheel-to-shaft. This is relatively easy to achieve with the guarantee of high-precision machining equipment for the integral casting type gearbox.
However, for the plate-welded gearbox, it is more difficult. Taking an export speed reducer produced by itself as an example, it is explained how to effectively control the deformation of the thin plate welded structural parts from the process.
1.1 The structure of the reduction gearbox The reduction gearbox is composed of the upper and lower halves. The upper and lower casings are mainly welded by the side plates, the coaming plates, the collars, the connecting plates and the suspension support screws. The material is 6.8mm thick. Q235A steel plate. The structure is as shown (the upper half box structure is substantially the same as the lower half box structure).
In order to ensure the good assembly of the two shaft holes of the box with the traction motor shaft and the wheel-to-shaft, and to meet the requirements of any two upper and lower halves that can be interchanged by the customer, the shaft hole, the upper and lower box joint surfaces The pin holes and pin holes for fixing the pin holes and the reduction box on other components must have very high dimensional accuracy and positional accuracy.
Shaft holes, tapped holes, pin holes and other welding accessories.
(5) Finishing, packing and leaving the factory.
1.3 Problems in the products processed according to the above process, measured by a three-coordinate detector, found that the two locating pin holes of the joint face are 1 mm in size, which makes the interchangeability of the upper and lower boxes unguaranteed; The oil baffle is unstable from 482 mm; the 1st plate uses the stone series tooling clamp and the Wei tool to machine the joint surface. Her Hus1234l suspension 1 support screw seat and the 1 port surface/parallelism, the verticality is too poor, resulting in the cabinet Not connected properly with other components.
2 Improved processing technology 21 Out of tolerance cause analysis After analysis, the main reason for the above-mentioned size tolerance is the welding deformation caused by the welding process of some small parts arranged after the shaft hole forming. These small parts must be welded with the center of the shaft hole as the positioning reference. Therefore, this welding process can only be arranged after the shaft hole is machined, and it cannot be arranged before machining. Therefore, welding deformation is inevitable. If an annealing furnace to stress-annealing process is inserted in the shaft hole processing step, the cycle will be lengthened and the cost will be greatly increased. In the case of mass production conditions, this process plan cannot be arranged, and a process method that can ensure product quality, simple process flow, and high work efficiency must be sought.
In order to reduce and eliminate welding distortion, a long-term natural aging method has been considered. Natural aging is simple and easy, no equipment is required, no cost is required, but the cycle is too long, and it is not suitable for products with short production cycle and urgent delivery requirements.
22 Improvement of processing technology In order to solve the problem of welding deformation after the processing process, the processing technology of the reduction box body was twice improved.
Improvements in the shaft hole machining process. For the boring, the shaft hole is roughened before welding, leaving a margin of 05, and then the oil slab is welded with the center of the shaft hole as the positioning reference, and then the two shaft holes are finely sized. For the drilling, the two locating pins are first welded. The hole is drilled to 10mm and then rough, and after the small parts are welded, the drilling tool is used to drill the 125mm positioning pin hole and the hole is larger than the size of the knife.
After the process was improved, the data was improved by the three-coordinate detector, but the dimensional accuracy requirements were still not fully met.
Increase natural aging treatment. Insert a short-term (3~5 days) natural aging treatment between the coarse and fine two twists and the drilling process. It was found that the product was tested by the three-coordinate detector, and all the data were all qualified, which proved that the process scheme was feasible. Now the product has been put into batch processing, the product quality has been stable, and the production efficiency is also high.
3 Conclusion Welding is carried out after roughing, and there are aging and finishing processes after the welding process. The stress and deformation caused by welding can be eliminated in the subsequent aging and finishing processes; the plate-type parts of the reduction gearbox are not thick enough to be easily dissipated, so the welding heat is not as large as the solid parts, the thermal stress is relatively uniform, and the residual stress It is also easier to release than a solid part. Therefore, the effect of aging treatment is better than that of solid parts, and the cycle of natural aging can be greatly shortened. This is the reason why the process adopts short-term (3~5 days) natural aging process.
The determination of the natural aging treatment cycle of the workpiece, and the material, shape, structural complexity, size and characteristics of the part, ambient temperature, heat before aging (such as welding, forging), force (such as cutting, plastic processing) and other factors The severity of the residual stress and the inhomogeneity are related to each other and are a comprehensive problem. Therefore, a more comprehensive and systematic study of this issue has its theoretical significance and practical application value.
(200603 12Cr1MoV heat-resistant steel pipe welding Taishan Group Taian City Pratt Machinery Manufacturing Co., Ltd. (271000) Zhao Zhongyi A coil produced in a boiler using 12Cr1MoV pearlitic heat-resistant steel material, its specifications are çºŸ108mmX 4mm Long-term work below 600 Â° C. Since the steel is used for the first time, a large number of relevant materials have been consulted, and a reasonable welding process has been developed through the welding process evaluation test.
1 The small-diameter thin-walled 12CriMoV tube working in the welding process can be welded by the process of not preheating before welding and without heat treatment after welding.
1.1 Welding method and selection of welding materials Because tungsten argon arc welding has good characteristics of small heat affected zone, small deformation, beautiful weld bead formation and high weld quality, it is decided to use tungsten argon arc welding for welding.
The selection of welding materials focuses on the following two aspects: First, welding 1 According to the relevant Fusuke I, for the long-term high temperature of the welding rod, the alloying elements in the lunar material should be the same as the base material/common content of the base material. Assembly welding: Before the welding, the small parts on the side plate are welded by the positioning die, and then the side plates, the surrounding plates, the collar and the connecting plate are assembled and compacted on the welding tire mold, and the relative welding is used to fix the relative parts. Position and then weld. As for the oil retaining plate and the positioning block, after the shaft hole is finished, the center of the shaft hole is used as a positioning reference for welding.
3 After the welding, the stress relief annealing is performed, and then the shot peening is performed to remove the burrs, the rust pieces on the surface of the box, and the welding slag and spatter generated during the welding.
4 Manually adjust the size of the box and the inner cavity positioning welding support plate to ensure that the size and shape of the box are fixed in the subsequent machining.
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