The advantages of forming cylindrical gears by plastic forming are as follows:
1) Productivity.Taking the small module gear used in passenger car as an example, the efficiency of traditional cutting and processing technology such as gear insertion, gear hobbing, etc. is 2-10 minutes/piece, while the efficiency of hot precision forging gear is about 5-10 minutes, while the speed of cold extrusion gear is slower from butadiene extrusion, and the processing efficiency is about 3-8 pieces/minute.It can be seen that if the hot precision forging cold extrusion compound forming process is used, the production efficiency can be increased by tens of times compared with the cutting process.
2) High material utilization.Under the traditional cutting and adding of gears, the tooth profile is formed by adding a large amount of metal to be removed by Ding. The material utilization ratio is only 40%-60%, and the total material utilization ratio of gear industry in China is only about 42%. The material utilization ratio of hot-precision forged gears is 70%-80% because there is machining allowance left on each surface of products. The cold-extrusion machining allowance is smaller than hot-precision forging. Only two excess metals need to be removed after machining.Except material utilization rate is more than 80%.It can be seen that if the hot precision forging cold extrusion compound forming process is adopted, the material utilization ratio can be increased by 20-40 percentage points compared with the cutting process.
3) High mechanical properties of parts.Composite process can improve gear strength and increase service life.Thermoforming can refine grains and cold forming can increase dislocations, so composite process can improve comprehensive performance of gear.Studies have shown that impact strength and fatigue strength of hot-precision forged gears are increased by about 30% and 5-10% respectively compared with those of forged-cut gears.