Determination of the processing technology of shaft gears

1. Determine the gear wool

　　 When determining the size of the wool, it is necessary to fully consider whether the machining allowance can meet the process needs, especially for gear carburizing and quenching, when the non-carburized surface adopts the 'surplus protection' method, the value of 'surplus protection' should be considered .

　　2. Rough machining of gears

　　 The rough machining of gears is to remove the machining allowance, to determine the benchmark for semi-finish machining, and to carry out the rough machining of the gear teeth at the same time. Gear rough machining should choose a good benchmark. The determination of the benchmark will have a greater impact on the distribution of the machining allowance of each machined surface and the relative position of the machined surface and the non-machined surface.

　　 When roughing, the chemical heat treatment of the parts should be considered-the non-carburized surface protection method during carburizing, generally there are copper plating protection method and margin protection method. The former is that the non-carburized surface is protected by copper plating, carburizing and quenching are carried out at the same time, and then the copper layer is removed, and there is no carbon layer on the copper-plated part. The latter is to leave enough machining allowance on the non-carburized surface (greater than the carburizing depth), and then fully carburize during carburizing, then car to remove the carbon layer on the surface without carburizing, and then quench.

　　 Select hobbing for rough machining. When determining the thickness of the gear hobbing indexing circle, it is necessary to consider the reduction of the carbon layer during gear grinding. Generally, the gear grinding allowance is not more than 0.2mm on one side; because the gear hobbing and gear grinding are not based on the same machining standard, the gear hobbing At the same time, the amount of runout of the gear tooth profile should also be restricted to avoid inconsistent margins during tooth grinding, resulting in uneven penetration of the tooth surface and reducing the wear resistance of the tooth surface.

　　3 Heat treatment of gears

　　 After rough machining of the gear wheel body and gear teeth, in order to meet the design drawing requirements, heat treatment is generally required, such as gear tooth carburization, quenching, cyanidation, nitriding, etc., to improve the mechanical properties of the material and meet the requirements Require. The gears of the hydraulic pump are carburized and quenched.

　　4 Semi-finishing machining of gears

　　 Semi-finishing mainly completes the processing of the secondary surface and prepares for the finishing of the main surface. Semi-finish machining is mainly turning, grinding, and correction of finishing standards. In the case of carburizing and quenching, the gears that are protected by a margin are divided into two processes, carburizing and quenching, and semi-finishing to remove the margin of protection is carried out in the middle.

　　5 Gear finishing

　　 Gear finishing is divided into the finishing of the wheel body and the finishing of the gear teeth.

　　(1) Finishing of wheel center. The finishing of the gear wheel body mainly includes the finishing and finishing of the precision surface of the part; it also includes the rolling, inserting, and broaching of the internal and external splines on the gear; the grinding, milling, and turning of the thread; the milling of the keyway, Insert processing; milling of craft flat table; lighten drilling and reaming of holes, etc. These processes are mostly arranged before the finishing of the outer circle of the bearing and the finishing (grinding) of the gear teeth.

　　(2) Finish machining of gear teeth. The precision of high-precision gears is mostly 6 to 7 grades, and the highest is 5 grades. According to the gear accuracy grade, gear tooth finishing of spur gears mostly uses grinding. When grinding teeth, choose appropriate cutting parameters to avoid grinding burns and cracks.

　　6 Non-destructive inspection

　　 Gear design drawings generally require non-destructive inspection. Gear parts are generally inspected by magnetic particle inspection. The magnetic particle inspection process is usually arranged before the completion of the mechanical processing and the final inspection.

　　7 Inspection process

　　The inspection process plays an important role in ensuring product quality and detecting waste products and stopping processing in time. In the gear process regulations, in addition to the final inspection after all parts are processed, intermediate inspections are generally arranged:

　　 (1) Before and after heat treatment and surface treatment by the outsourcing unit;

　　 (2) Some dimensions are not easy to measure after all gears are processed, such as the empty slot of the inner hole of a shaft gear. Intermediate inspection can be carried out after the process of machining the empty slot, and this part of the size will not be checked during the final inspection. .

　　8 Surface treatment process

　　 After passing the gear inspection, in order to meet the requirements of anti-rust and wear resistance, the surface of the gear generally needs to be blued, oxidized and phosphated, copper-plated, silver-plated and other surface treatments to meet the requirements of anti-rust and wear resistance.