The traditional method of correcting deformation after quenching of a gear is to honing and grinding the tooth flanks. However, the honing efficiency is low, and only the surface quality can be improved. Special honing equipment needs to be purchased. The cost is high, the grinding efficiency is low, the cost is too high, the technical level of the workers is high, and waste products are prone to occur.
After the gear is hardened, the tooth surface strength is obviously improved, the temperature of the cutting zone rises above 1000 degrees Celsius, the hardness of the tooth surface after quenching is as high as HRC58-62, and the tooth is subjected to alternating mechanical during the hard tooth surface scraping process. Stress and thermal stress. Therefore, in addition to having sufficient strength, the blade body material must have high wear resistance, red hardness and easy plunge. The scraping process is carried out using the "material 22" carbide tool, and the effect is good.
The shape of the scraping hob is basically the same as that of a general gear hob. The hob teeth are made of fine-grained carbide inserts. Since the hob has a large negative rake angle (corresponding to the blade inclination angle), the root of the tooth first cuts into the tooth surface of the gear during the cutting process, and then gradually transitions to the top of the tooth. Due to the inclination of the cutting edge, the cutting width of the teeth is reduced at the same time, and the blade width is gradually cut.
Therefore, the cutting resistance is reduced to make the cutting process continuous and smooth. The chips are acicular spirals. Tests have shown that the larger the negative rake angle, the smaller the cutting force, cutting heat and vibration during the scraping process, the less likely the chipping is, the higher the durability of the teeth, but the more difficult it is to manufacture. Experience has shown that cutting performance is best when the negative rake angle is -45°, but the tool manufacturing is difficult. It is best to use a method of scraping in place, which is beneficial to reduce the wear of the tool, increase the life of the tool, and avoid the occurrence of chipping or crushing.
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