1. Material Selection of Blank
The mechanical gear blank is simple in structure and small in size, and it has many steps and shafts. Its mechanical properties are relatively high and its precision is high, and it does not need to be easy to process in small batches or in large batches. Therefore, blank die forgings are generally selected. The blank has small machining allowance, good surface quality, high mechanical motion strength and high survival rate.The material used for workpiece is generally 45 steel. The standard of nominal accuracy for workpiece size of blank is 1, grade it1, nominal accuracy dimension is 100, length is 50.
2. Baseline Parts Selection
Mainly according to the relevant parts design drawings and the daily use and maintenance of related parts.The mean values of_3 spline hole, elliptical runout of end face and parallelism runout can only be guaranteed by correct straight line positioning datum. Therefore, the correct selection of positioning datum should be comprehensively analyzed in time.
3. Axis Selection of Rough and Fine Datum
Axis selection for rough and fine datums: A good selection of rough datums is also essential for circuit operating systems and parts such as tandem drive gears.For parts that respond to rotating volume, we usually use the outer circular arc as the basis for thickness.Accuracy and accuracy of the benchmark are selected after the completion of a processing procedure, and after the 933 spline hole each procedure uses each spline hole as a benchmark for positioning accuracy.In this way, the principle of mutual coincidence of fixed datums and the principle of mutual coincidence of fixed datums are met respectively.When we process some material surfaces, there may be some reference differences or overlaps at the same time, so we need to pay attention to the reference conversion for different size chains.