Robot Industry - RV Reducer Industry

Technical Overview of Reducer

The working principle and main classification of reducers

In the field of mechanical transmission, a reducer is an intermediate device that connects the power source and the actuator. Its main working principle is to reduce the speed and increase the torque of the prime mover through the mechanical transmission device. That is, by meshing the large gear on the output shaft with the gear on the input shaft with fewer teeth, the high-speed power of the prime mover is reduced in speed and the output torque is increased. Therefore, reducers are widely used in low-speed and high torque transmission equipment, and are also the core factor affecting robot performance.

There are various types and models of reducers to meet the different power transmission needs of different industries. Decelerators can be classified in various ways. According to control accuracy, reducers can be divided into general transmission reducers and precision reducers. The control accuracy of general transmission reducers is low, which can meet the basic power transmission requirements of general mechanical equipment; Precision reducers have high precision, long service life, small return clearance, and high reliability, making them suitable for high-end manufacturing fields such as industrial robots, service robots, collaborative robots, and industrial automation with high precision control requirements.

Precision reducers mainly include RV reducers and harmonic reducers, which are the core components of high-end equipment manufacturing industries such as robots. Their average cost accounts for about 35% of the total cost of industrial robots. RV reducers and harmonic reducers are widely used in high-end manufacturing fields such as industrial robots, service robots, collaborative robots, and industrial automation with high precision control requirements, and have high technical barriers. Among them, harmonic reducers are mainly used in lightweight and low load operating environments; RV reducers are mainly used in operating environments with medium to high loads, high torque, and high stiffness. They have higher technical requirements, greater production processes and assembly difficulties, and lower localization rates. Currently, Japan's Nabotek dominates the global market.

Due to differences in technical characteristics such as transmission principles and structures, the two have different focuses and complement each other in downstream products and application fields, and are applied in different scenarios and end industries.

Working principle and characteristics of reducer
According to the definition of GB/T34897-2017 "Precision bearings for RV reducers in rolling bearing industrial robots", RV reducers are transmission machinery consisting of a planetary reducer front stage and a cycloidal pinwheel reducer rear stage, with a large transmission ratio and self-locking function under certain conditions.

The RV reducer is developed on the basis of traditional needle pendulum planetary transmission, and its reduction structure consists of the front stage of the planetary reducer and the rear stage of the cycloidal pinwheel reducer. At least two eccentric shafts are used to connect the secondary reduction mechanism; The shell and cycloidal pinwheel are driven by solid castings and steel components, forming a closed differential gear system. The RV reducer not only overcomes the disadvantages of general cycloidal pinwheel transmission, but also has a series of advantages such as high precision (backlash less than 1 degree), high rigidity, high durability, high output density (high torque and compact), large reduction ratio range, and low vibration.

Due to the relatively late start of China's RV reducer industry, there is still a certain gap in the overall technical level of enterprises within the industry compared to internationally advantageous enterprises. In the domestic RV reducer market, as domestic manufacturers continue to overcome technical challenges, their technological strength and competitiveness continue to improve, and the gap between product performance and foreign leading levels continues to narrow. According to the "Report on the Development of China's Robot Industry (2022)" by the China Electronics Society, the core competitiveness of key components in China's industrial robots continues to improve, and the trend of localization of core components is gradually emerging. Taking reducers as an example, a group of excellent enterprises such as Green Harmonic (mainly harmonic reducers) and Environmental Technology (mainly RV reducers) have become the leading force in the development of the domestic reducer market with continuous research and development investment, high precision manufacturing capabilities, strict quality control, and constantly improving product systems.