Technical analysis of gear hobbing and hot finishing
Sintered Tungsten Carbide Hard Metals Products Zhuzhou Jingfeng Carbide Tools Co., Ltd , https://www.zzjfcarbide.com
How far can the traditional high-speed steel hob and wet cutting technology go?
The driving role of carbide hobs and dry-cutting processes is obvious to all. For high-volume production of gear lines, can high-speed steel hobs be replaced by carbide hobs? Has dry cutting become the only way to hobbing, or is it still going to be wet?
Carbide hobs are particularly suitable for hobbing automotive gears. However, the application of carbide hobs in Europe is still not high, due to the development of new high-speed steel materials and high-performance tool coating technology, carbide hobs and high-speed steel hobs during hobbing time The upper gap can be controlled at about 15%; the carbide hob is expensive, and if the number of gear workpieces is not enough, the cost of using a carbide hob will be high; in addition, when using a carbide hob Be especially careful, and the hobbing parameters and the corresponding hobbing procedures should be carefully crafted. Only modern hobbing machines can use the carbide hob to properly hobbing, and a significant investment is required to update the hobbing equipment. In the case of Samputensili, about 25,000 hobs are produced each year, of which cemented carbides account for only about 3%. That is to say, the annual production capacity of carbide hobs is up to 750.
Dry gear cutting is another matter. Due to environmental requirements and high cost of handling cooling waste, users in Europe, the United States and Japan generally consider dry hobbing when selecting. In developing countries such as China and India, controlling pollution is also an urgent requirement. But it takes time. Once the society's control over pollution issues becomes more stringent, gear dry cutting will also develop rapidly.
Which gear finishing is more popular for gear finishing, between gear shaving and grinding, which gear finishing is more popular?
This first has to distinguish one industry from another. For example, most of the gears used in the automotive industry rely on shaving. Some companies also grind the rear drive gears just to eliminate any deformations that occur on the ring gear.
The reduction of the gear machining time mentioned above is mainly attributed to the development of new gear cutters, modern gear machine tools and the resulting reduction in finishing allowance and the improvement of the quality of the gears before grinding. In addition, compared with gear grinding machines, modern CNC gear shaving machines are often priced at half the power, high-precision gear grades before heat treatment (up to DIN 5-6 grade); and machining compared to gear-thread grinder grinding The cycle is also shorter.
For gears in the automotive industry, especially those used in automatic transmissions, we can control the deformation caused by heat treatment after shaving to a few microns; in addition, the correction of the tooth profile and tooth orientation helps to compensate for the deformation. Due to the emergence of modern razor sharpeners, such as the S400 GS produced by Samputensili, the two parameters of tooth profile and tooth orientation can be quickly and easily modified; in mass production, the benefits of shaving are much better than those of grinding. In fact, shaving can guarantee quality and reasonable price. Samputensili is one of the top companies in the gear machinery industry, and the razors it has produced in recent years have yet to show signs of slower production. At the same time, the number of gear grinding machines is also increasing. The rapid development of the gear processing technology, the operation of the gear machine tool is efficient and fast, and the gear grinding wheel has also developed rapidly. This is mainly reflected in ceramic grinding tools, CBN grinding wheels, electroplating grinding wheels and so on. The above-mentioned grinding tool is used for gear grinding to shorten the machining cycle. As the processing cycle is gradually reduced, the cost of gear grinding is also greatly reduced. It should be pointed out that some industries have high requirements on the quality of gears, and some industries need to achieve special tooth shapes, so they must be ground. For example, the heavy truck industry, aerospace engineering, and the gearbox industry for power generation and substation rely on grinding for gear finishing. In these high-power industries, gear grinding is already in an absolute advantage.
The new technology gears for mass production of gears are becoming more and more demanding, and the requirements for variable speed noise are getting lower and lower. To achieve the dual goals of quality and noise, this requires higher precision gear machining and extremely complex gear toothing and tooth profile, with the aim of minimizing the error of the variable speed drive. This means that in the next period of time, grinding is still the main method of gear mass production, and the gear grinding process may be more widely used. But pay special attention to the unit cost of gear processing. So far, the benefits of low cost and high efficiency shaving are obvious. When grinding is a complete success in gear finishing, shaving can be replaced on a large scale. In short, no matter which gear processing method is chosen, pay more attention to the actual use.
In view of the considerable development of hobbing processing, it is highly probable that the high precision obtained after hobbing does not require shaving. The further development of gear sintering technology has also made a great contribution to gear manufacturing, but this method is currently in its infancy and it is difficult to accurately predict future development trends.
As mentioned above, although the development of gear processing technology has changed a lot, the unit processing cost of gears will certainly not change. In large-scale production lines, gear processing structure adjustment should be guided by this parameter. The development of new processes is of great benefit to the improvement of quality and precision. With the refinement of gear product technology, the requirements for these two key elements are becoming more and more strict. Although it is very difficult to meet such high requirements, we must also pursue high standards. However, it is not enough to focus on high indicators. We must pay more attention to the standard of achieving low prices and good quality. Otherwise, the new gears and new functions will not be welcomed by the market, and the development level of gear technology will not be improved. . In industries with high technical content, the trend of precision and reasonable price should be coexisted at the same time.