A manufacturing error measurement methodology for a rotary vector reducer cycloidal gear based on a gear measuring center

Abstract

A manufacturing error of a cycloidal gear is the key factor affecting the transmission accuracy of a robot rotary vector (RV) reducer. A methodology is proposed to realize the digitized measurement and data processing of the cycloidal gear manufacturing error based on the gear measuring center, which can quickly and accurately measure and evaluate the manufacturing error of the cycloidal gear by using both the whole tooth profile measurement and a single tooth profile measurement. By analyzing the particularity of the cycloidal profile and its effect on the actual meshing characteristics of the RV transmission, the cycloid profile measurement strategy is planned, and the theoretical profile model and error measurement model of cycloid-pin gear transmission are established. Through the digital processing technology, the theoretical trajectory of the probe and the normal vector of the measured point are calculated. By means of precision measurement principle and error compensation theory, a mathematical model for the accurate calculation and data processing of manufacturing error is constructed, and the actual manufacturing error of the cycloidal gear is obtained by the optimization iterative solution. Finally, the measurement experiment of the cycloidal gear tooth profile is carried out on the gear measuring center and the HEXAGON coordinate measuring machine, respectively. The measurement results verify the correctness and validity of the measurement theory and method. This methodology will provide the basis for the accurate evaluation and the effective control of manufacturing precision of the cycloidal gear in a robot RV reducer.

Meshing contact analysis of cycloidal-pin gear in RV reducer considering the influence of manufacturing error

“…According to the working principle of RV cycloidal-pin gear [6], the position relationship of cycloidal-pin gear is shown in Fig. 1…”

“…However, we should note that the parabolic modification is another important method in the modification design of cycloid gear, it is a single tooth non-backlash mismatch modification method, which can ensure that the main meshing area is close to the conjugate profile, the non-meshing area has the appropriate backlash, and the transmission error is reasonable under the influence of installation error, manufacturing error and other factors [22]. According to the meshing characteristics of cycloidal-pin gear transmission, the profile geometry of cycloid gear with parabolic modification mainly depends on six parameters [6]: the teeth number of cycloidal gear z c , the eccentricity a, the roller radius r rp , the roller position r p , the parabolic modification coefficient a c and the parameter angle 0 of mismatching reference point. The tooth profile model with parabolic modification is shown in Fig.…”

“…Discrete tooth surface points or tooth profile errors of the cycloidal gear can be obtained using the gear measurement center [6]. The continuous actual machining tooth profile of the cycloidal gear can be obtained by high-precision fitting of discrete points on the tooth surface.…”

“…Yu et al [5] proposed an analysis method called non-Hertz flexibility matrix method (NHFMM) for the teeth contact of the modified profile of pin gear. Li et al [6] proposed a methodology to realize the digitized measurement and data processing of the cycloidal gear manufacturing error, which provides the basis for the effective control of manufacturing precision of cycloidal gear in robot RV reducer. Lin et al [7] presented a method for kinematic error analysis and tolerance design of cycloidal gear reducers and developed an algorithm based on the discretization of the cycloidal tooth profile to complete tooth contact analysis of the cycloidal gear reducer.…”

A New Tooth Profile Modification Method of Cycloidal Gears in Precision Reducers for Robots

“…From the above studies, it can be seen that the traditional modification design is mainly realized by changing the size and center position of the grinding wheel in the generation process. At present, the gear grinding technology and precision measurement technology are increasingly mature [18][19][20], so the modification methods of cycloidal gears are more flexible [21] and various tooth profile optimization technologies are available. The profile shape of a cycloidal gear directly affects its transmission performance and the pressure angle distribution on the cycloid profile determines the force transmission performance of gear teeth in meshing.…”