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

Abstract

The tooth profile modification of cycloidal gears is important in the design and manufacture of precision reducers or rotary vector (RV) reducers for robots. The traditional modification design of cycloidal gears is mainly realized by setting various machining parameters, such as the size and center position of the grinding wheel. The traditional modification design has some disadvantages such as complex modification calculation, uncontrollable tooth profile curve shape and unstable meshing performance. Therefore, a new tooth profile modification method is proposed based on the consideration of the comprehensive influences of pressure angle distribution, meshing backlash, tooth tip and root clearance. Taking the pressure angle and modifications of tooth profile as the parameters of the modification function and the meshing backlash of gear teeth as constraints, the mathematical model for tooth profile modifications is built. The modifications are superimposed on the normal direction of the theoretical profile—the force transmission direction. The mathematical relationship between the modifications and the pressure angle distribution, which determines the force transmission performance, is established. Taking the straight line method, cycloid method and catenary method as examples, by means of the tooth contact analysis technology, the transmission error and minimum meshing backlash, which reflects the lost motion, of the newly modified profile are analyzed and verified. This proposed method can flexibly control the shape change of the modification profile and accurately pre-control the transmission accuracy of the cycloid-pin gear. It avoids the disadvantages of traditional modification methods, such as uncontrollable tooth profile shape and unstable meshing accuracy. The method allows good meshing characteristics, high force transmission performance and more precise tooth profile curve. The study provides a new design method of the modified profile of cycloidal gears.

A Loaded Analysis Method for RV Cycloidal-pin Transmission Based on the Minimum Energy Principle

“…Tooth contact analysis is one of the important means of studying meshing characteristics. The analysis method and model have been generated by some researchers [28] and [29]. In this section, the mathematical model of the cycloidal-pin transmission will be given for later use [6].…”

A Novel Approach to Calculating the Transmission Accuracy of a Cycloid-Pin Gear Pair Based on Error Tooth Surfaces

“…Sun et al [5] proposed a compound modification method combining negative isometric and negative offset mod ification to reduce the influence of PMs on backlash. Li et al [19] proposed a novel method for PMs to improve the motion accuracy and modification quality that comprehensivel To avoid the tooth interference caused by MEs and AEs and obtain better lubrication conditions, profile modifications (PMs) are necessary for cycloid-pin drives. This also has a non-negligible effect on the TE and backlash of cycloid-pin drives.…”

“…Sun et al [5] proposed a compound modification method combining negative isometric and negative offset modification to reduce the influence of PMs on backlash. Li et al [19] proposed a novel method for PMs to improve the motion accuracy and modification quality that comprehensively considered the effects of the backlash, pressure angle distribution, and tooth tip and root clearance. In addition, many scholars have studied the torsional stiffness, transmission efficiency, load analysis, and optimization design methods of cycloid-pin drives.…”

Research on Clearance Elimination Control Based on Linearization

“…The rotary vector (RV) reducer provides low transmission backlash but has a complex structure, and [5] therefore proposed a matching algorithm and applied it to selective assembly of the RV reducer to realize high assembly accuracy. Reference [6] proposed a new tooth…”