Research status of design theory of automobile gear hob

At present, the production and sales volume of China’s automobile industry has reached more than 22 million through explosive growth, and the industry has become a pillar industry of the national economy. And the competition among enterprises is becoming white hot. Whoever can provide products with excellent performance and lower price will win the favor of the market. Therefore, all enterprises try their best to improve product performance and reliability and reduce production costs.

As the key and important part of automobile products, gear must also improve the accuracy and stability of automobile gear products from the production process. In the production process, the cost of cutting tools accounts for about 20% of the total production cost, and the cutting tools directly determine the processing efficiency of parts. Therefore, hobs must be taken as the primary research object of automobile gear parts.

Automobile gears can be manufactured by casting, plastic deformation and cutting. At present, due to the low precision, the casting method and plastic deformation are usually not used in the manufacturing process of automobile gears. The main application is cutting method. According to the working principle, it can be divided into profiling, non instantaneous center envelope method and generation method.

The tool of profiling method is to use forming tool to process gear, and the tooth shape of tool should conform to the shape of tooth groove; The cutter without instantaneous center envelope method has no instantaneous center with the gear to be cut in the process of tooth cutting. The tooth shape of the gear to be cut is the envelope of the continuous position of the cutting edge of the cutter. When machining spur gears, the tooth profile of the cutter conforms to the shape of the groove of automobile gears. At this time, the profiling method is consistent with the non instantaneous center envelope method. This cutting tool principle is mainly used for automobile gears with few teeth and special requirements for non involute tooth profile and tooth root transition curve.

Generating method is the most widely used method in automobile gear processing industry. In short, it is processed by using the principle of a pair of automobile gears meshing or gears meshing with racks. During machining, the instantaneous center lines of the tool and the gear to be cut make pure rolling without sliding with each other. The tooth shape of the machined automobile gear is the envelope of the continuous position of the cutting edge of the tool. The main advantages of this method are: the processed automobile gear has high precision, high processing and production efficiency, and can realize semi-automatic or automatic operation. It is widely used in the design of automobile gear hob.

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