Gear grinding and manufacturing
Rack grinding refers to the grinding of the tooth surface of the rack and each side after heat treatment to eliminate burrs and deformation to improve the accuracy of the rack. The general grinding precision is German standard level 5 or level 6, with an accuracy of up to 0.022mm.
The grinding wheel manufacturing process uses special gear grinder equipment, such asHangzhou Machine Tool Group Co., Ltd.OrBlohm and MAEGERLE companies of the German Schleiflin group (13522079385)In the specially produced rack grinding machine, the rack is positioned in the jaws of the clamping body and then clamped hydraulically. The profile grinding wheel is installed on the main shaft of the equipment and rotates at high speed driven by the motor to grind the rack. powerfully as a whole. During the gear grinding process, a large amount of cooling water flushes the grinding area, cooling the workpiece and the grinding wheel and discharging a large amount of grinding fluid. It can grind 4-7 grids at the same time. Once the cast wheel reaches the end of its stroke, the wheel is ground by the cast diamond roller, then moves up and quickly returns to the starting point to prepare for the next cycle. The cooling water is cut off, then the. the clamp is released and the support is removed. Then add the second batch of racks.
The image above shows the tightening method, with 7 brackets tightened at the same time. Domestic companies FAW Guangyang Steering Device Co., Ltd. and Jingzhou Henglong Auto Parts Co., Ltd. use the above process to process racks.
There is also the following form:
The grinding wheel used for gear grinding should be customized according to the product requirements, including the relevant parameters of tooth shape and the required number of teeth. Domestic companies generally choose Norton “NORTON” grinding wheel with a grain size of 80. and a model of 500×180×203.2W80FVR (53A80). The outer diameter is collectively called quasi-320 (determined by the specific product), and the number of grinding wheel racks can theoretically reach 2,500.
The grinding wheel must be equipped with a specially shaped diamond roller to dress the grinding wheel. Formed diamond rolls are expensive and have a long order cycle. It usually takes 90 days to import them from abroad and costs around 160,000 yuan.
Processing cycle time is an important indicator for measuring equipment processing capabilities. The grinding wheels are determined based on the tooth shape parameters of the rack (such as total tooth height, etc.), the diameter of the rack and the previous state of the rack. There are two so-called pre-order states:
The first is to roughly mill the required grinding tooth parts, using an ordinary vertical milling machine and a triangular disc milling cutter, milling 4 teeth at a time, using a manual collet , leaving a margin of 1 mm on the upper surface of the tooth. and a margin of 1 to 2 mm on both sides;
The other is to directly grind the teeth without rough milling. In terms of processing efficiency, the first state can save about 1-2 minutes/cycle compared to the second state.
The processing cycle of a single piece of small diameter bracket (outer diameter 22 ~ 25 mm) is generally 0.9 ~ 1.0 min. The single-piece processing cycle time of large diameter bracket (outer diameter 26~30mm) is generally 1.6-1.8 minutes. The deeper the teeth are ground and the coarser the outer diameter, the longer the processing time. The annual processing capacity of a gear grinding machine can reach 250,000 gear racks. The integral grinding wheel processing has the characteristics of high dimensional accuracy, good tooth surface finishing and good dimensional stability. It is used in high-end products with high quality requirements, such as steering racks used in some high-end Mercedes-Benzes and. BMW cars.
Grinding gears, grinding wheels instead of tool cutting, the cost of electric power is relatively high, and the grinding mud needs to be removed. Instead, the iron filings after cutting can be removed as scrap and reused in the steel mill. In order to reduce the cost of using grinding wheels for workpiece grinding and improve the grinding efficiency, you can refer to tooth broaching and milling. First, use a general milling machine and a disc cutter to mill a plane over the rack teeth, leaving one. margin 0.5 ~ 1mm. Gear grinder grinding can significantly reduce the cost of the grinding wheel, accelerate the production rate and increase the production capacity.
Comparison between rack and milling rack
The difference between the rack and the precision rack: The rack has been heat treated, and the tooth surface is ground on four sides, with high precision and long service life. The difference between ground rack and finely milled rack is in the process. Firstly, the rack is ground as a whole after heat treatment, while the finely milled rack is ground after heat treatment except for the outer surface of the teeth. Due to different processing techniques, there is a large difference in precision between the two, and the precision of the grinding frame after grinding is also relatively high. This is also the biggest difference between the two.
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Methods of designing and processing gears, and related matters relating to the design, manufacture and operation of cutting tools used to process gears.
Related technical issues such as gear milling cutter design calculation methods, related application development, automatic drawing of CAD secondary development, etc.
In terms of tool application, cutting parameters, coating and tool life, problems encountered in processing and solutions, etc.
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