Common Types of Reducers Used in Industrial Robots

In industrial robotics, there are several commonly used types of reducers:

1. RV Reducer

The RV reducer mechanism is a novel transmission mechanism based on the traditional rotating planetary wheel pinion gear. It is widely applied in the joints of industrial robots due to its high efficiency. The power of the Servo engine in industrial robots is transmitted through gears on the input shaft of the reducer, resulting in a reduction in speed. The ratio of teeth and gears determines the percentage of transmission efficiency.

2. Harmonic Reducer

The harmonic reducer is a new transitional mechanism in the gear system and is typically used in industrial robots with minimal loads. It consists of elastic and rigid wheel gear generators, offering slightly higher utility than flexible wheel systems. The harmonic reducer exhibits significant driving advantages, such as compact size, fewer components, a single engine range of 50-4000%, and a transmission efficiency of 92-96%.

3. Planetary Reducer

In simple terms, the planets in the planetary reducer revolve around the sun, much like the planets in our solar system. The planetary reducer, also known as a planetary gear system, functions as a reducer to lower the rotational speed of the engine, thereby increasing torque in industrial robots.

The working principle of the planetary reducer involves reducing gears. When the sun rotates under the driving force, the engagement of the planetary wheels causes them to rotate. Simultaneously, the other side of the planetary wheels works together with the internal ring and circular gears on the inner wall of the housing, allowing the planetary wheels to rotate in the same direction as the driving frame along the sun wheel's rotation direction within the driving force. This creates a revolution motion of the internal ring and circular gears. The wheel revolving around the sun represents one revolution.​

 Industrial robots typically use RV reducers, harmonic reducers, and planetary reducers. RV reducers offer suitable speed control for Servo engines, reducing the speed to the desired level for each component of the industrial robot while increasing the generated torque.

How to Deal with Heating Issues in Harmonic Reducers

 The harmonic speed reducer plays an important role in the operation of mechanical equipment. Due to its small size, light weight, and high-precision reduction effect, it is widely used by many manufacturers of mechanical equipment.

 

As a reduction tool, the harmonic speed reducer is bound to encounter some problems after prolonged use, such as heating issues. Today, I'm going to share some knowledge about how to deal with the heating of harmonic speed reducers.
 
Generally, there are two main reasons for the heating of the speed reducer. One is related to problems with the eccentric bearings, and the other is related to lubricating oil. Of course, there are other issues as well, such as improper installation of new machines. These two are relatively common situations. Now, let's discuss how to identify and solve these problems.
 
When we notice that the harmonic speed reducer is heating up, we can start by checking the lubricating oil to see if the machine is running low on it. If there's insufficient or dried-up lubricating oil, we can add the appropriate amount.
 
If even after adding lubricating oil, the temperature of the harmonic speed reducer doesn't decrease, then it's not an issue with the lubricating oil. In that case, we need to continue troubleshooting. Next, we can look at the duration of machine operation, as prolonged continuous operation and overload can lead to heating, which is a normal occurrence. The solution to this problem is simple—just shut down the machine for a period of time.
 
Another aspect to consider is whether the installation of the harmonic speed reducer and the machine is appropriate. Inappropriate installation can also lead to heating issues. This problem is similar to the problem of eccentric bearings in the harmonic speed reducer and requires a certain level of technical expertise to identify. If you're not familiar with this, it's advisable to seek assistance from the speed reducer manufacturer for testing.
 
Once the problem is identified, solving it becomes straightforward. For those not well-versed in speed reducers, after checking the lubricating oil and prolonged operation, if the issue persists, seeking help from a professional harmonic speed reducer manufacturer would be beneficial for quickly resolving the problem and avoiding any potential major issues.

How to Choose a High-Precision Planetary Gearbox?

How to choose a high-precision planetary reducer?

1.  The input dimensions of the high-precision micro planetary gearbox can be customized according to the motor dimensions provided by the user. If you find that there is no suitable size during the selection process, you can communicate with the gearbox manufacturer for customization.

2.  It is crucial to understand the maximum permissible input shaft diameter of the high-precision planetary gearbox. Most gearboxes are connected to the motor through a flexible coupling. Insufficient knowledge about the permissible shaft diameter can severely affect the maximum value of the input shaft hole.

3.  During the selection process, it is also important to consider the size of the permissible flange input based on the actual usage requirements.

4.  Determine the maximum input speed of the high-precision planetary gearbox. Different engineering projects have varying speed requirements. Customization or adjustment by professional technicians should be done based on the actual project needs. Proper planning during the initial purchase can save a lot of trouble in the future.

5.  The rated torque of the gearbox must be smaller than or equal to the output torque.

6.  Understand the required gear ratio, wattage of the servo motor, and the level of precision needed for your machinery. Generally, higher precision comes at a higher price. Users can select according to their specific needs.

      

By adopting a differential gear mechanism and thin cross roller bearings, high-precision micro planetary gearboxes achieve an ultra-flat shape, contributing to the compact size of the equipment. The combination of small size and excellent parameters achieves the optimal balance between performance, price, and size.

The proper way to install, use and maintain an RV reducer

The proper installation, usage, and maintenance of an RV reducer are crucial for ensuring the mechanical equipment working well. Therefore, during the installation of the reducer, it is important to strictly follow the installation sequence outlined below and assemble the components carefully. Before installation, it is necessary to confirm the integrity of both the motor and the reducer, and meticulously inspect the dimensions and matching tolerances of the various parts connecting the driving motor to the reducer.

This refers to the dimensions and fit tolerances between the positioning protrusion and shaft diameter of the motor flange, and the positioning groove and aperture of the reducer flange; as well as the removal of dirt and burrs from the surface of the mating parts.

1. Unscrew the plug from the process hole on the side of the RV reducer flange. Rotate the input end of the reducer and align the hexagonal screw cap with the process hole. Insert the hexagonal tool and loosen the hexagonal screw.

2. Hold the driving motor and ensure that the key way on its shaft aligns vertically with the input end hole of the RV reducer. Insert the motor shaft into the reducer input end hole. During insertion, it is essential to ensure concentricity and parallelism between the two flanges. If there is any inconsistency in concentricity or lack of parallelism, the cause must be identified. Additionally, it is strictly prohibited to use hammering force during installation. This prevents excessive axial or radial forces that could damage the bearings of both components and allows for assessment of the proper fit through the assembly feel.

The method for determining concentricity and flange parallelism is as follows: after mutual insertion, the flanges should fit snugly with consistent gaps.

3. To ensure even force distribution between the flanges, first loosely tighten the motor fastening screws without fully tightening them. Then, gradually tighten the four fastening screws in a diagonal pattern. Finally, tighten the screws securing the reducer input end hole. It is crucial to tighten the motor fastening screws before fully tightening the screws securing the reducer input end hole.

Note: The correct installation between the RV reducer and the mechanical equipment is similar to the correct installation between the reducer and the driving motor. The key is to ensure consistent concentricity between the output shaft of the reducer and the input shaft of the driven component.

 

Planetary Reducers Used for CNC Cutting Machines

Since CNC cutting machines for carpentry use synchronous belts, which inevitably have a certain tension force, prolonged usage can lead to a decrease in accuracy. However, CNC cutting machines require high precision from the machinery. Generally, they need to handle heavy loads and require torque that exceeds the servo motor's capacity. This problem can be effectively solved by connecting the servo motor output torque through FUBAO planetary reducers.

The advantages of using FUBAO planetary reducers are as follows:

1. Increased torque: To increase the output torque, one method could be to directly increase the servo motor's output torque. However, this approach would require expensive high-power servo motors with stronger structures. Increasing torque is directly proportional to increasing control current, which would lead to the need for larger drivers, power electronic components, and related electromechanical equipment, resulting in a significant increase in control system costs.

By using FUBAO dual-support structure planetary reducers to connect the servo motor, the transmission accuracy is high, the gear transmission is smoother, the transmission noise is low, the efficiency is high, and the stability is better.

2. Improved performance: Improper matching of load inertia is one of the main reasons for unstable servo control. For large load inertia, the best control response can be achieved by adjusting the equivalent load inertia inversely proportional to the square of the reduction ratio. From this perspective, planetary reducers provide the best match for servo control applications.

(FUBAO planetary reducers have an integrated structure between the input shaft and the sun gear, which eliminates the error in the connection between the input shaft and the sun gear compared to split structures, rivets, or key connections. This results in higher precision, higher concentricity, greater load torque capacity, and smoother transmission.)

3. Increased equipment lifespan: Planetary reducers can effectively address the attenuation of the motor's low-speed control characteristics. The control performance of servo motors deteriorates to some extent due to the decrease in speed, especially in terms of signal acquisition and current control stability at low speeds.

Therefore, using reducers can allow the motor to achieve higher speeds. (FUBAO planetary reducers have an internal ring gear directly inserted into the body, made of high-quality alloy steel 42Crmo, with a process of quenching and nitriding through imported gear insertion machines, ensuring precision and hardness.)

Based on the above analysis, FUBAO dual-support planetary reducers are the best choice for CNC cutting machines in carpentry. The applicable models for CNC cutting machines include WPG090L1, WPG115L2, and WAB180, with motor power ranging from 400 watts to 3 kilowatts.

 

Replacements of Reducers in China Application

Some domestic companies in China are making progress in the field of servo motors and drivers, and the quality of their products is catching up with international standards, securing a certain market share.

Julu Intelligent previously stated that their RV reducer has entered the industrialization phase. Fengguang Precision Harmonic Reducer is currently in the small-scale trial production and process improvement stage. Lude Harmonic indicated that the newly developed electromechanical integrated products have now entered the trial production stage and are awaiting mass production.

According to industry insiders, the localization rates of harmonic reducers and RV reducers are both in an accelerating phase, with various companies entering the market and expanding production to compete for market share.

The mainstream reducers on the market include RV reducers and harmonic reducers. The former is mainly used for robot joints weighing over 20kg, while the latter is used for robot joints weighing under 20kg. "For example, light-load robots use harmonic reducers."

Industry insiders have mentioned that the technical barriers for harmonic reducers are high, and domestic replacements are accelerating. The domestic localization rate of harmonic reducers for industrial robots is approximately 30%, and it is expected to increase to 40% by 2025.

Zhongdali De stated that the performance gap between their domestically produced reducers and foreign products is not significant, and there is a trend of accelerating domestic replacements. Currently, there is strong downstream demand, and many new application scenarios have emerged, prompting the company to expand production in recent years and plan for further expansion in the future.

Drawing from the rise of industrial robots in Japan, autonomous control of core components is a prerequisite for the rise of Chinese industrial robots.

At present, harmonic reducers have achieved technological breakthroughs and can replace imports. However, due to performance issues such as transmission accuracy, torsional rigidity, and stability, RV reducers still rely on imports.

 

Methods for solving the failure of planetary reducers

     

In response to the wear problem, the traditional solution is to repair by welding or brush plating and then machine processing, but both have certain drawbacks: the heat stress generated by welding cannot be completely eliminated, which can easily cause material damage, leading to bending or fracture of the components.

     while brush plating is limited by the thickness of the coating, it is easy to peel off. Both of these methods involve repairing metal with metal, and cannot change the "hard to hard" mating relationship. Under the comprehensive action of various forces, it will still cause wear and tear again. It is impossible to solve some large bearings on site.

     As for the leakage problem, the traditional method requires disassembling and opening the gear reducer, replacing the sealing gasket or applying sealant, which is not only time-consuming and laborious, but also difficult to ensure the sealing effect, and leakage will occur again during operation. Meijiahua polymer materials can handle leakage on site, and the material has excellent adhesion, oil resistance, and 350% elongation, overcoming the impact of gear reducer vibration, and effectively solving the problem of gear reducer leakage for enterprises.

      During long-term operation, gear reducers often experience faults such as wear and leakage, the main ones being:

1. Wear of the gear reducer bearing chamber, including the wear of the housing bearing box, the internal hole bearing chamber of the box, and the wear of the gearbox bearing chamber

2. Wear of the gear reducer gear shaft, with the main wear occurring at the shaft head, keyway, etc.

3. Wear of the gear reducer transmission shaft bearing position

4. Leakage of the gear reducer joint surface

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