Parallel axis precision grinding of micro-tooth internal thread with the coarse-grains CBN wheels

Abstract

As an important part of precision transmission system, internal threads with high precision, high hardness and small pitch are widely used in the fields of aerospace, numerical control machine tools, medical equipment and construction machinery. Aiming at micro-tooth internal thread, the research on parallel axis precision grinding of micro-tooth internal thread with the coarse-grains CBN wheels is carried out. Firstly, the grinding wheel section is designed based on the principle of parallel axis grinding of micro-tooth thread, and the theoretical error is systematically analyzed. Secondly, the maximum undeformed chip thickness of parallel axis thread grinding based on coarse-grains is established. Finally, the precision grinding experiment of internal thread is carried out. The optimal parameters can be obtained: the grinding wheel diameter is 17.08 mm, the grinding wheel angle is 90.13°, the lead is 3 mm, the pitch diameter is 21.06 mm. In this case, the maximum axial error is about 0.1 μm, the tooth profile angle error is 0.01° and the rounded radius error is about 3.5 μm. Considering the machining effect and efficiency, the truing depth is 150 μm, the feed rate is 0.2 mm/s, the grinding speed is 17,000 r/min and the grinding depth is 5 μm.