The parameter verification of involute spur gear reverse engineering includes modulus, tooth shape angle, crown height coefficient, tooth root height coefficient and displacement coefficient. This paper verifies whether the parameter calculation result is reasonable by using two methods: tooth profile verification and paired gear verification in reverse software. In gear surveying and mapping, due to the influence of factors such as tooth profile wear, tooth profile modification and manufacturing error, and the accuracy grade of the original design gear, the current gear calculation result is only close to the original design parameters to a certain extent, so the verification result is also to determine the proximity between the two.
1. Verification of tooth profile shape of involute spur gear in reverse software
The steps of tooth profile verification in the software are as follows:
1) Import the three-dimensional scanning data into the reverse software, draw a circle with three points in the reverse software, and fit the tooth top circle and tooth root circle.
2) The pitch of tooth base and the pitch of tooth base circle are calculated by drawing the pitch coefficient and pitch of tooth base circle respectively.
3) For the intersection of the excessive degree circle and the tooth profile, make the tangent of the base circle and extend it to intersect with the tooth profile respectively, measure the length of the common normal, and then connect the intersection of the circle center, the indexing circle and the tooth profile, and the intersection of the circle center, the base circle and the tangent line respectively, and measure the included angle between them, that is, the tooth profile angle.
2. Reverse engineering is verified by matching involute spur gears
The necessary condition for gear meshing is that the modulus and tooth profile angle are equal respectively. Through the mapping and calculation of the basic parameters of reverse engineering of paired involute spur cylindrical gears, determine whether the modulus, tooth profile angle, crown height coefficient and tooth root height coefficient of the two gears are the same. During the verification of displacement coefficient, it is also necessary to know the center distance a of the two gears, such as a ‘= a = m (z1 + Z2), It is the gear with constant position and high modification, otherwise it is the gear with angular modification.