The spiral cylindrical gear is mainly used to transfer the rotary motion between the staggered axis and the parallel axis. Because the involutehas parallel shaft, it is often used in gear reducer. A single helical gear is actually a helical gear, and its tooth surface is an involute helical gear. Because of its high transmission efficiency, large transmission power range, long service life, accurate transmission ratio, reliable operation, good transmission performance, and easy installation, manufacturing, measurement, etc., it has been widely used.
Gear shaping technology is based on the principle of forming or generating method, using gear shaper to process internal and external gears or racks. The early appearance of Lorenz CNC gear shaper and Liebherr CNC gear shaper made the multi coordinate control of CNC gear shaper possible. These two kinds of CNC gear shapers can keep the cutting speed stable, ensure the surface roughness of gear direction, and meet the special needs of gear processing flexibly and conveniently. In order to meet the market demand, a variety of new CNC gear shaper machines have been launched in China, such as yk5180 CNC gear shaper produced by Tianjin No.1 Machine Tool Plant, and yk5132 CNC CNC gear shaper produced by Nanjing No.2 Machine Tool Plant Co., Ltd. Because the production efficiency is low when cutting gears with large module, gear shaping technology is suitable for processing gears with multiple teeth, small module and narrow tooth width.
Gear hobbing technology belongs to generating method, which envelops the gear profile to be processed through the cut marks left on the gear blank by the blade. The gear hobbing machine of Liebherr company of Germany, which adopts modular design, is more flexible in design, and can form gear hobbing and gear shaping only by changing the cutting head; the wf3500 gear hobbing machine of Huth company can not only roll teeth, but also roll teeth, grind teeth, gear shaping and measure gear wheels, and can change the milling cutter in 30 minutes. Gear hobbing can process the accuracy of gear to grade 8-9 at one time, and also can make the rough machining and semi finish machining of gear higher than Grade 7. Although the hobbing has a relatively high movement accuracy, but because the tooth surface is formed by the envelope of the hob teeth during machining, the number of cutter teeth participating in cutting is limited, so the tooth surface roughness is not high.
With the application of diamond dressing roller, CNC technology and CBN grinding wheel becoming more and more mature, the machining accuracy of forming grinding teeth has been greatly improved and reliably guaranteed. For example, the CNC forming gear grinding machine launched by samputesili company of Italy can not only grind with high precision, good stability and high efficiency, but also deeply grind any required gear profile curve. When there is deviation in gear grinding, the trimming roller will automatically trim. As long as the machining accuracy of the first helical gear reaches the requirements, the machining accuracy of the subsequent helical gear will not change basically, which not only reduces the inspection workload, but also enables the helical gear to meet the requirements of high accuracy and performance. In the process of gear hobbing and gear shaping, the tool wear is inevitable, and the tool wear can not be fully compensated in the process of machining. Therefore, in terms of the stability and complete interchangeability of the forming process of spiral gears, gear hobbing and gear shaping can not be compared with forming gear grinding.