Differential Roll-Scanning Technology for Accuracy Measurement of Fine-Pitch Gears

The accuracy measurement of fine-pitch gears within module 0.02-0.2mm in batch production is one of the puzzle problems in industry because of its small amout of dimension and rigidity. Based on the gear integrated error measurement technology developed by CTRI in China and Frenco in Germany, a kind of differential roll-scanning measuring technology and a differential fine-pitch gear integrated error measuring machine first developed by the authors are introduced briefly in the paper, including the working principle and calculation formulas of ‘two synchronized rotate-driving systems, one differential-compensation closed-loop measurement’ , the stucture of ‘spindle on spindle’ and ‘differential composite driving spindle system’ of the master gear, and the unique master gear with ‘every other tooth thinned’ followed the principle of overlap coefficient not bigger than 1 for a few certain gear pairs，and also the special made hob for making the thinned master gear. The measuring results of four items of deviations, including pitch, profile, tangential composite and integrated deviations of product fine-pitch gears show the feasibility and prospect of the new developed measuring technology and machine in future industry application.