Consideration of Materials Used in Trochoidal Gear Reducer Based on Stress Analysis of Internal Components Aimed at Weight Reduction

In recent years, the demand for industrial robots has been increasing year by year and is expected to continue to grow in the future.On the other hand, efforts toward the Sus- tainable Development Goals (SDGs) and carbon neutrality are spreading worldwide.This paper aims to develop a lightweight reduction gear for energy-saving robots. To reduce the weight of robots, it is necessary to replace conventional metal materials with new lightweight materials. However, weight reduction generally reduces rigidity, which tends to lower the high-speed and high-precision performance required of industrial robots. The authors have studied the possibility of replacing metal parts with machined CFRP, POM, and 3D printer resin parts, and have examined the adaptability of these parts. In the previous report, we experimentally compared the weight, no-load running torque, torque–torsional characteristic, and dynamic torque transfer efficiency of 20 combinations of metal and resin reduction gears. In this report, we focus on the yield strength of materials and analyze the load distribution, stress of reduction gear components, taking into account the effects of assembly and fabrication errors. We then calculate and compare the output torque per volume and weight of four types of reduction gears using metal and resin combinations. Under the condition of designing within the elastic range of the materials, it was demonstrated that using resin gears could increase the maximum output while saving space and reducing weight. Additionally, the validity of the theoretical values was verified by comparing them with FEM analysis results.