1. High precision circular arc shrink gear is machined by full process milling and UMC grinding

China is a big automobile manufacturing country. With the rapid development of domestic social economy, the demand for automobile gears is increasing. In China, it is common to use the five tool method to process circular arc shrink gears for automobile gears. But foreign countries have explored to implement the full process method of gear milling, and then through the heating process, use the UMC method of gear grinding to process high-precision circular arc shrink gears.

The advantages of this method compared with the traditional five tool machining method are as follows:

First, the processing efficiency is improved and the cost is reduced. Because this method reduces the times of machine tool adjustment and cutter head replacement, the cutting time of each pair of gears can be reduced by one third. Therefore, when processing batch workpieces, it can effectively reduce the number of adjustments and greatly improve the production efficiency. This method belongs to the whole process cutter head system of dry cutting, and its cost can be greatly reduced compared with the wet cutting cutter.

The second is to ensure that the geometric accuracy of gears of the same batch is consistent. When the whole process method is used for gear cutting, the big wheel and the small wheel are clamped at the same time, and two sides are processed at one time, which effectively ensures the geometric accuracy of the same batch of gears and makes the precision stability of gear products better.

Third, the strength of the gear pair is improved and the tool life is extended. When using the five tool method to process circular arc shrink gears, the cutter head for cutting teeth needs to cut from one end of the tooth slot to the other end, and the minimum tooth slot width of the tool limits the width of the tool tip. The gear is processed by the whole process method, and the tooth grooves of the big wheel and the small wheel have a fixed width in the direction of the gear rectangle. This equal slot width ensures the maximum tool tip distance and the maximum fillet radius of the tool tip during gear cutting, which can avoid tool wear and prolong tool life. In addition, when machining the fillet of the tooth root and the tooth ground surface, the smoothness of the connection can be improved and the strength of the gear can be improved.

Fourth, it can realize dry cutting and gear grinding. Five knife method requires three cutter heads, which is not really dry cutting from the perspective of modern processing theory. The whole process processing can realize the dry cutting of modern processing. The cycloidal gear with equal height cannot be grinded, and the high-precision bevel gear cannot be grinded with the cycloidal gear with equal height. However, the full process method is used to mill the gear, and the arc shrink gear grinded after the heating process can produce high-quality and high-precision bevel gear.

2. Machining Klingelnberg Bevel Gear with Five Tool Method

Large bevel gears with higher bending strength are required to transmit power on domestic large reducers and other equipment. The processing technology of such large bevel gears is higher than that of ordinary automobile gears. A German company has proposed a gear processing method called HPG and AMK series machine tools, which are specially used to process gears with large module and small number of teeth that require different small module and large number of teeth from automobile gears. They are called Klingelnberg bevel gears in China. The machining method mainly uses the cycloidal contour teeth, and uses the double body cutter head with 5 groups of path teeth for machining. After the processed tooth germ is heated, the CBN cutter head with negative rake angle is used for scraping. This processing method can eliminate the problem of gear accuracy decline caused by heat treatment deformation, increase the residual compressive stress generated on the gear surface during heat treatment, improve the bearing capacity of the gear, and is especially suitable for the production of various bevel gears with small quantity and large variety. At present, based on the cutting technology of cycloidal bevel gears, the five tool method has been used to process Klingelnberg bevel gears on domestic CNC gear milling machines.

With the rapid development of domestic economic construction, the demand for large-sized and high-precision spiral bevel gears in petroleum exploration, metallurgical manufacturing and other industries is increasing. To study the processing technology of large-sized and high-precision spiral bevel gears, we need to break the foreign technology monopoly, narrow the gap between the domestic gear industry and the international gear manufacturing powers, and focus on independent research and development of core key technologies, Continuously improve the machining accuracy and quality of large-sized high-precision spiral bevel gears.

Source: gear drive

Mechanizm napędowy Transformation and upgrading direction of machining technology for large-sized and high-precision spiral bevel gears