Joints of a six-axis robot
Different reducer products are used for each joint
According to different structures, precision reducers for industrial robots can be divided into five categories. RV reducers and harmonic reducers are the most mainstream precision reducers for industrial robots. According to different structures, precision reducers can be divided into five categories: harmonic gear reducers, cycloidal pinwheel planetary reducers, RV reducers, precision planetary reducers and filter gear reducers. They are different in various performance indicators of the reducer such as accuracy, torque, stiffness, transmission efficiency, etc. Among them, RV reducer and harmonic reducer are the most mainstream precision reducers for industrial robots.
RV reducer and harmonic reducer are the most important reducers used in industrial robots, and RV reducer has a tendency to gradually replace harmonic reducer in advanced robot transmission. 75% of the world’s precision reducer market is occupied by Japan’s HarmonicaDrive and Nabtesco, of which Nabtesco produces RV reducers, accounting for about 60% of the share, and HamonicaDrive produces harmonic reducers, accounting for about 15% of the share. RV reducers are mainly used for robot joints above 20 kg, and harmonics are used for robot joints below 20 kg. Unlike the harmonic reducer, the motion accuracy of the RV reducer will be significantly reduced with the increase of use time, and there is a trend to gradually replace the harmonic reducer in the advanced robot transmission. However, due to the more complex components and higher bearing strength of the RV reducer, it is not only more difficult to manufacture than the harmonic reducer, but also the investment scale of its production line is much larger than that of the harmonic reducer.
The domestic companies involved in RV precision reducers include the listed company Qinchuanmachine toolShanghai Electromechanical Co., Ltd., Great Wheel Co., Ltd., the new third board company has the only target Henghua Co., Ltd., non-listed companies include Nantong Zhenkang, Hengfengtai, Wuhan Essence, Shanghai Essence, Shandong Shuike, etc., and there are non-listed companies involved in harmonic reducers. Suzhou Green Harmonic Drive Technology Co., Ltd., Beijing Zhongji Meike Harmonic Drive Co., Ltd., etc.
The precision reducer in my country started late, and the counterattack has many challenges. Compared with the decades of accumulation of Japanese giants, China’s research on precision reducers for industrial robots started late, and the technology is immature, resulting in a situation where precision reducers cannot be self-sufficient and rely heavily on imports. The RV reducer needs to transmit a large torque, withstand a large overload impact, and ensure the expected working life. Therefore, the over-positioning structure is used in the design, and the processing is very difficult. The seemingly simple RV reducer is actually a challenge to my country’s industrial infrastructure system. Expensive imported general-purpose machine tools may not be able to produce precision parts, not just by introducing a few imported equipment. Some domestic companies have made major breakthroughs in the technical level, and they have not yet formed a large sales scale.
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