Based on expounding the engagement theory of the planar envelopment hourglass worm, principle of dummy gyration center was analyzed detailedly and applied to machining the worm. The planar wormgear were finishing ground on the THM63100Ⅳ. Machining error of wormgear was tested and transmission error of worm gears was measured by the motion property testing and analysing system(FMT). Bachlash was adjusted and contact marks were observed during assembling. The results of error detection show that the accuracy of wormgear is up to 5 degree in china GB 10095-88 and the worm gears drives smoothly. The results of assembly show that backlash is adjusted successfully in the range of 0.003~0.025mm and contact marks are consistent with theoretical contact zones. It is concluded that the harding teeth surface of planar wormgear and its worm can be ground simply and the backlash of worm gears can be adjusted easily. Research and development of the planar worm gears is valuable.
