Gear is an important part of agricultural machinery, which has a wide range of applications. Although the working conditions of gears are different, their wear and damage are basically the same. The inspection and identification methods for gears are as follows:
(1) Appearance inspection and identification. Look at the fracture and damage of the teeth, whether the teeth are broken, peeled, pockmarked and severely worn. Measure the tooth thickness with gear caliper, and measure the length of the common normal line with the common vernier caliper. If the damage of the tooth tip is not serious (generally speaking, the slag is broken) and has little effect on the whole tooth surface, it can be used continuously; if the tooth surface peels off, it can not be used continuously. The sliding gear is often damaged on the long end face of gear, and it should be repaired when the damage is nearly 1 / 4 of the whole gear length. There are spots on the whole tooth surface. If the tooth surface falls off linearly at the indexing circle, the gear needs to be repaired. It’s just the early spots. It needs to measure the tooth thickness to decide whether to repair.
(2) Instrument measurement method. Use gear caliper to measure the tooth thickness of gear indexing circle chord, or use common caliper to measure the length of gear common normal line. There are three methods:
① Measure the tooth thickness based on the tooth top circle. The accuracy of measurement is affected by the accuracy of tooth top circle, but it has little influence on the inspection of worn gears, so it can be used to identify the gears with worn tooth thickness.
② When measuring the thickness of fixed chord and fixed chord, for the standard gears with the same module and different number of teeth, the thickness and top height of the chord on the graduation circle are constant. This shows that gears with the same module have the same fixed chord. This is very convenient in gear production and inspection.
③ The inspection before gear repair only determines the wear degree of gear thickness, and then determines whether the gear needs to be repaired according to the wear condition.
Generally, the gear with normal wear is just near the graduation circle. Therefore, it is better to measure the thickness of the gear indexing chord before gear repair. It is also a good method to measure the tooth thickness of worn gear with the length of common normal, which is convenient and rapid, and does not need to measure the benchmark. It is not suitable to measure worm gear and helical gear with narrow width.
(3) Measure the backlash with rolling lead wire. Press the lead wire into a lead piece thicker than the tooth gap, roll it at the meshing place of the teeth, take out the lead piece, and measure its thickness with an outside micrometer, that is, the gear tooth gap.