Based on the local image of the visual involute gear pitch measurement method

Abstract This paper aims to rapidly measure the small and medium module spur gear pitch in industry and solve the complex problem of visual measurement. It proposes an algorithm for a single-gear pitch based on the statistical information of the tooth profile image edge’s transition zone. Firstly, the local image of the involute gear was processed; Then, based on the geometric characteristics of the involute tooth profile edge, a pixel point parameter database has been established, the transition zone's pixel information is inversely mapped to the base circle to calculate the initial phase angle of the tooth profile edge involute. Finally, the gear pitch is calculated by using the initial phase angles of two adjacent tooth profiles with the same name. In addition, through theoretical analysis and simulation calculation, the sine curve model of the initial phase Angle error of the tooth profile caused by the eccentricity of the base circle positioning is obtained. The results show that: 1.When the eccentricity e ≤ 40 µm, when the positioning error Δψj ≤ 1°, it can meet the measurement requirements of 5-level precision gear; 2. Measuring the pitch of the same 5th-grade precision gear, the difference between the two pitches measured by the visual gear measuring instrument and the Coordinate Measuring Machine is 0.4 µm and 0.2 µm, respectively; 3. The maximum single-pitch deviation of the visual gear measuring instrument and the M&M3525 gear measuring center is on the same pitch. The difference between the two is 0.7 µm, and the total deviation of the pitch accumulation is 3.3 µm. It indicates that this gear pitch visual measurement method can meet the rapid measurement requirements of the 5th-grade precision spur gear pitch.