The precision reducers used by global industrial robots are basically monopolized by Japan. In recent years, although there are mass-produced RV reducers in China, few domestic robot companies choose them. At present, the reducers in the Chinese market generally rely on imports.
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▲Japanese Yaskawa robot peels peas with a knife
As a traditional manufacturing powerhouse, the reducer products of Germany, Italy, Japan and other countries are in the leading position in the industry in terms of materials, design level, quality control, precision, power density, reliability and service life.
In the field of mechanical transmission, the reducer is an intermediate device connecting the power source and the actuator. Usually, it uses the high-speed running power of the electric motor and internal combustion engine to achieve the purpose of deceleration through the small gear on the input shaft and the large gear on the output shaft. And transmit more torque.
Driven by the development of aerospace, robotics and medical equipment, the demand for high-performance precision reducers with simple and compact structure, high transmission power, low noise, and stable transmission has increased, among which RV reducers and harmonic reducers are precision reducers There are two types of reducers that are the most heavy in the machine.
The precision reducer is a power transmission mechanism that uses a gear speed converter to reduce the number of revolutions of the motor to the desired number of revolutions and obtain a larger torque device.
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▲Nabtesco reducer
At present, there are not many manufacturers of precision reducers with large-scale and reliable performance in the world, and most of the market share is occupied by Japanese companies: Nabtesco's RV reducer accounts for about 60%, Harmonica's harmonic reducer accounts for about 15%, There is also Sumitomo Heavy Industries (SUMITOMO, proportion not found). Especially in the field of robotics, the proportion of applications is overwhelming.
Nabtesco (Nabtesco) is formed by the merger of two Japanese companies, Teijin Seiki and Nabok (which produced Japan's first automatic door in 1956). As manufacturers of motion control systems and components, both companies have mastered high-end core technologies and controlled a large market share in their specific business fields.
As the world's largest manufacturer of precision cycloid reducers, Nabtesco produces high-performance reducers, hollow shaft reducers, and single-axis servo actuators and controllers.
The precision equipment produced by it has high torque, high rigidity and high overload impact load capacity, and at the same time has high precision and very low return clearance, and is widely used in satellites, radar antennas, industrial robots, semiconductors and welding technology and other industries field of automation.
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▲A precision reducer is applied to each joint of an industrial robot
Japan's Harmonic Drive Systems Inc. (HDSI for short) is a leader in overall motion control. The Harmonic Drive combined harmonic reducer produced by it has the characteristics of light weight, small size, no gear backlash, and high torque capacity. It is widely used in Various cutting-edge fields such as industrial robots, humanoid robots, semiconductor liquid crystal production devices, photovoltaic equipment, optical instruments, and precision machine tools.
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▲Internal structure of harmonic reducer
In order to cover the low reduction ratio field that the harmonic reducer cannot achieve, HDSI products also involve the precision planetary gearbox type harmonic reducer Harmonic Planetary. The unique deformation process of the inner ring gear can make the planetary gear mesh with it more tightly, eliminate the backlash, and achieve the transmission error of the precision level.
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▲ Harmonic Planetary Gears harmonic planetary reducer
Harmonic drive reducer is a gear transmission system that relies on a wave generator to produce controllable elastic deformation of flexible gears and meshes with rigid gears to transmit motion and power from the beginning.
Japan's Sumitomo SUMITOMO is a construction machinery manufacturer under the Sumitomo Group, one of the world's top 500 companies with a history of more than 400 years. After Sumitomo products developed the first hydraulic excavator with its own technology in 1967, Sumitomo is currently active all over the world. Silhouette of hydraulic excavator.
Sumitomo reducer includes various types of reducer, such as Sumitomo large helical gear reducer, Sumitomo planetary gear reducer, Sumitomo helical gear reducer, Sumitomo worm gear reducer, etc. The reduction ratio is large, the efficiency is high, the pin tooth meshing system is sleeve-type rolling friction, the meshing surface has no relative sliding, and the first-stage reduction efficiency can reach 94%.
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As a pinnacle of the precision machinery industry, the technical threshold of the reducer is very high. The RV reducer is completely composed of high-precision components and gears meshing with each other. Precision detection technology places extremely high demands.
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Most of the research and development of domestic enterprises obtain data through reverse engineering, and they are fully aware of it but do not know why. Therefore, although some domestic enterprises have made major breakthroughs in the technical level, there are difficulties in the research and development of domestic reducers in terms of accuracy maintenance, precision life and product life. Various difficulties lead to poor consistency of domestic reducers. low reproducibility.
On the other hand, the equipment for processing and manufacturing the parts of the reducer is very expensive. For example, the unit price of the Megale surface grinder is close to 10 million yuan. Without sufficient production support, the amortization cost of equipment is frighteningly high.
The cost of domestic precision reducers is higher than that of foreign competitors, but their performance is worse than that of their competitors. Of course, the sales volume is not good, and it is impossible to achieve economies of scale and profitability. Without profit, without batches, there will be insufficient resources to carry out technological improvement, exploration and research and development, and there will be no way to form quality control, and there will be no way to improve technology and performance.
At present, there are two main types of reducers used in the field of robots, one is RV reducer, and the other is harmonic reducer. In articulated robots, because the RV reducer has higher rigidity and rotation accuracy, the RV reducer is generally placed on the base, the boom, the shoulder and other heavy loads, and the harmonic reducer is placed on the forearm , wrist or hand.
For high-precision robot reducers, Japan has an absolute leading edge. At present, 75% of the precision reducers in the global robot industry are monopolized by Japan's Nabtesco and HarmonicDrive (commonly known as RV reducers and harmonic reducers in the industry), including ABB, FANUC, The reducers of international mainstream robot manufacturers such as KUKA are provided by the above two companies.
According to industry insiders, ABB, FANUC, Yaskawa, KUKA and other international mainstream robot manufacturers all provide reducers from the above two Japanese companies, and they have very strict cooperation conditions with the two companies, that is, when using this The products of the two companies can no longer use the products of other companies, otherwise the cooperative relationship will be terminated.
Core components have always restricted the rapid development of Chinese robots. If we want to form the industrialization of robots, get rid of the constraints of foreign robot companies, and win autonomy in the field of robots, we must accelerate the localization of reducers on the agenda.
