Research On The Precision Measurement System Of Planar Double-enveloping Worm Based On CCD

The planar double-enveloping worm is an important transmission form in mechanical transmission. And it has many advantages such as high transmission ratio, several couples of teeth meshing simultaneously, double touching lines on each interfacing surface, easy to form lubricative film, heavy load. Therefore it's used widely in metallurgical industry, weaponry industry and many other fields.The worm tooth surface is a complicated space surface. So it's difficult to measure the tooth profile, tooth thickness and other errors. At present, the error detection of worm depends on experience and conventional contact measurement. The conventional contact measure method have a lot of shortcomings such as low efficiency, low testing precision.Up to now, the problem remains in suspense.Through the study on the current status and development of gear measurement technology ,the non-contact measurement technology and error detection for worm at home and abroad, the paper puts forward a new measurement system for worm error detecting based on image processing technology, CCD technology, DSP technology.This paper analyses the forming principle of the worm, deduces the tooth equation of two packs worm and acquire the discrete model of instantaneous contact line. And the discrete model is simulated. Main error detecting items of worm are introduced briefly.At the same time, image processing fundamental knowledge and image processing key technology such as image smoothing, image binaryzation, edge detection, least square fit are elaborated. According to the worm image characteristic and imaging condition, it selects the suitable image processing operators for the detecting system by experimental comparison. And the coordinate transformation of worm contact line two-dimension coordinate is presented. According to the different error detecting item, different error analysis algorithm is produced.The overall project is designed and working principle is discussed in this paper. The key modules such as image processing system, optical system, display platform, mechanical structure are mainly described. The CPLD driver circuit, SAA7114 circuit and other circuits are designed. On the basis of relevant theory, the measurement system software is completed. The software includes CPLD driving timing for CCD using VHDL,DSP routine and special software for worm error detecting system.Lastly, the experiment study on error detecting of planar double-enveloping worm based on current experimental condition is carried out. And the real data of the measured worm is acquired. The feasibility and correctness of error measurement system are proved by experiment results.The non-contact error measurement system based on CCD designed in this paper explores a new way for precision measurement of planar double-enveloping worm. The measurement system has important theoretical value and certain value in practical application.