Technological changes in the new class of tractor starter gears
The process measures adopted According to the analysis results of the gear quality not meeting the requirements, we have taken corresponding process measures from the following aspects: The main process measures for mechanical noise prevention The tooth cutting process is the key process to ensure the accuracy of the gear, mass production The positioning of the inner hole and the end surface of the workpiece is high, and the precision of the blank is high. Therefore, the machining of the blank becomes an important process for ensuring the precision of the gear processing. The upper limit is shifted by 1/31/4, which avoids interference when the gear meshes. And noise.
The upper limit process measures for gear tooth breaks take into account that the working conditions of the engine gears are complex and variable, and the load is large, so it should have high contact fatigue strength. We refer to the gear materials of other diesel engines, and on the one hand, propose to use HT20-40 for the original. The composition of the material is improved, and on the other hand, new materials are actively tried. Among them, the main and passive gears of the oil pump are replaced by the powder metallurgy 1 forming gear, and the scheme is proved to be feasible, and the cost is greatly reduced and the economic performance is improved. In addition, we have also carried out a process experiment on the gray cast iron material to the ductile iron material. The conclusion is that replacing the gray cast iron with ductile iron will significantly improve the mechanical performance and reliability of the gear. However, in the actual process experiment, due to the influence of tools, machine tools and other factors, there are some problems in the processing of ductile iron materials. Further research and improvement are still needed. At present, the cast iron gear material of the new engine has been changed to HT250, which is better than the original. The HT20-40 has a significant improvement in performance.
Other measures to ensure the gears Most of the equipment of our factory was made in the former Soviet Union. It has been used for nearly 50 years, and the precision is reduced, which makes the gear precision difficult to guarantee. During the engine test, the problem of insufficient oil supply to the oil pump was found, which caused more failures and caused the crankshaft to lock up in severe cases. Check the original design of the main and passive gears of the oil pump are within the tolerance range, but the tooth tolerance of the required process is not large, the value is 0.020.04mm, which causes the pump oil to be insufficient when the gears mesh. The cause of the tooth misalignment is caused by the machine tool factor. The moving guide of the Y54 (514) gear shaping machine table is seriously worn. The manufacturer leaks the lubrication hole during the manufacturing process. After re-lubricating the hole and adjusting the guide rail, the tolerance is measured. Both are within the required range and the accuracy of the common normal tolerance is improved. This improvement also has guiding significance for other gears, prompting us to pay attention to the problems caused by poor tooth tolerance during the gear machining process, and to control the tooth tolerance when necessary.
In the production, the J38 gear hobbing machine, 1K36 hexagonal car, 3161T cylindrical grinding machine and other machine tools were also modified. For example, the digital display equipment is added to the 3161T grinding machine to improve the machining accuracy of the gear end face and ensure the accuracy of the positioning of the blank blank. The 1K36 hexagonal car adopts a new process during the repair to ensure the long-term stability of the guide rail to improve the machining accuracy of the tooth blank. The improved effect improves the machining quality of the gears through the improvement of the gears of the engine gear trains, which not only reduces the scrap rate, but also ensures the quality of the diesel engine.
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