Reasons for using helical gears in the production of reducers

Reasons for using helical gears in the production of reducers

        The main disadvantage of spur gears is that they oscillate. Some variation in the involute profile may occur along the entire flank at the same time, whether due to design, fabrication, or deformation. This will result in a regular, once per tooth excitation, which is often very strong. The resulting oscillations cause both high loads on the gears and noise. A further disadvantage is that the additional strength sometimes obtained by the meshing of two pairs of teeth during the contact time cannot be used because the stress is limited by the condition of the meshing of a single tooth during the cycle.

        The helical gear can be regarded as a cylindrical gear formed by dislocating a group of thin-toothed gears, so that the touch of each piece is at a different part of the tooth profile, so that the effect of compensating the error of each thin-film gear occurs. This compensation effect is due to the The elasticity of the teeth is very useful, which leads to the result that teeth within 10mm of error can average the error, so under load conditions, they can run as smoothly as teeth within 1mm of error. Since at any instant there will be two teeth meshing about half the time (assuming a coincidence of about 1.5) this provides an additional advantage in terms of strength. Therefore, the stress can be based on 1.5 times the tooth width instead of one tooth width.

        It is difficult and uneconomical to fabricate and assemble a large number of thin spur gears, so one-piece gears with teeth in the helical direction are fabricated. Helical gears are not like spur gears, which can cause undesirable axial forces. But the advantages in oscillation and strength far outweigh the disadvantages caused by axial thrust and slightly increased manufacturing costs. Therefore, helical gears are used instead of spur gears in the production of reducers.