A Brief Introduction to Robot Bearings

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In recent years, with the continuous development and improvement of technology, robots have been widely used in industrial and manufacturing fields. As one of the key parts of robots, robot bearings have played a key role in the operation of robots.

First, common bearing requirements for robots

1. Can withstand the axial, radial, overturning and other integrated loads.

2. Small size and lightweight.

3. It must have the technical characteristics of high load, high slewing accuracy, high running stability, high positioning speed, and high repeat positioning accuracy.

4. It can meet the characteristics of long life, low friction torque, high reliability.

Because of the particularity and complexity of the robot’s working environment, bearings that meet the above requirements must be required to fit in the robot to ensure safe use.

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Second, the robot commonly used bearings

Due to technical requirements and environmental influences, the development of modern industrial robots has become lighter, which requires that the supporting bearings have a more lightweight structure. Bearings must meet the performance requirements of industrial robots on bearing capacity, accuracy, stiffness, and frictional torque within a limited installation space. It is difficult to meet this requirement with standard general-purpose bearings. At present, there are two major types of bearings commonly used on robots. One is a thin-walled bearing of the same cross-section, and the other is a cross cylindrical roller bearing.

1.Equal-section thin-wall bearings

Equal-section thin-walled bearings are different from ordinary bearings in that their cross-sections are mostly square in size and their dimensions are designed to be fixed. In the same series, the cross-sectional dimension is constant, and it does not increase with the increase of the inner diameter, so it is called a constant-section thin-wall bearing. Equal-section thin-wall ball bearings include thin-wall four-point contact ball bearings, thin-wall angular contact ball bearings, and thin-wall deep groove ball bearings. They are mostly used in the waist, elbow, and wrist parts of industrial robots. In the case of the same internal diameter, thin-walled ball bearings with more sections have more steel balls than standard rolling bearings, so the internal force distribution of the bearing is improved, the elastic deformation at the contact between the steel ball and the channel is reduced, and the bearing’s Carrying capacity.

2. cross cylindrical roller bearings

The internal rollers of the cross cylindrical roller bearings are arranged at 90 ° perpendicular to each other. A single bearing can simultaneously bear the combined effects of radial force, axial force and overturning moment. A cage is installed or isolated between the rollers The block can prevent the inclination of the rollers or the mutual grinding between the rollers, and effectively prevent the increase of the friction torque. In addition, the rollers are arranged in a vertically crossed arrangement to avoid the locking of the rollers. At the same time, because the inner and outer rings of the bearing are divided, the gap can be adjusted, and even if pressure is applied, high rotation accuracy can be obtained. Crossed roller bearings are widely used in industrial robots for waist rotation, articulated robot shoulders, arms, wrists and other rotating parts due to their light composite structure, high turning accuracy, good rigidity, and stable friction torque.

Robot bearings must not only ensure sufficient bearing capacity but also require precise positioning and flexible operation. Therefore, bearing design analysis must consider a number of indicators for optimal design. In addition to the above two kinds of bearings, there are harmonic reducer bearings, linear bearings, articulated bearings, etc. in the robot, but mainly used are thin-walled bearings and thin-walled cross roller bearings of equal cross-section.

Brief Introduction of Wind Turbine Slewing Bearing

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In recent years, with the rapid development of the economy and population expansion, the demand for energy has also increased. Directly leading to energy reduction, environmental pollution problems have intensified. The country is vigorously developing clean energy. Wind power generation is a mature and promising power generation method in new energy power generation technology. Its safety and cleanliness have been rapidly developed at home and abroad in recent years. The slewing bearing of the wind turbine is an important part of the mechanical equipment, which ensures the normal operation of the wind power generator.

First, the definition

Wind turbine bearing can also be called wind power bearing. It is a kind of special bearing. It has a harsh environment, high maintenance cost, and high life. Wind turbine bearings mainly include yaw bearing, pitch bearing, spindle bearing, and shifting box bearings, generator bearings.

Second, wind power bearing structure

The structural forms of bearings for wind turbines mainly include four-point contact ball bearings, crossed roller slewing bearings, cylindrical roller bearings, spherical roller bearings, and deep groove ball bearings. The yaw bearing is installed at the connection between the tower and the cockpit, and the pitch bearing is installed at the joint of the root of each blade and the hub.

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Third, technical requirements

1. material standards

The standard stipulates that the material of the yaw and pitch bearing ring is 42CrMo. The heat treatment is treated by integral quenching and tempering. The hardness after quenching and tempering is 229HB-269HB, the surface of the raceway is quenched, and the quenching hardness is 55HRC-62HRC. Due to the complicated force of the yaw and pitch bearings of the wind turbine and the relatively large impact and vibration of the bearing, the bearing is required to withstand both impact and large loads. The life expectancy of the wind turbine’s main engine is 20 years, and the cost of bearing installation is relatively large. Therefore, the life of yaw and pitch bearing is required to reach 20 years.

2. low-temperature impact

Low temperature impact energy requirements for yaw and pitch slewing bearing rings: -20°CAkv is not less than 27J, and the Akv value in the cold state can be determined by the user. Wind turbines may work in extremely cold areas, with ambient temperatures as low as -40 °C, bearings operating at around -20 °C, and bearings must withstand large shock loads at low temperatures.

3.bearing clearance

Yaw and pitch bearings have special requirements in terms of play. Compared with the yaw bearing, the impact load of the pitch bearing is relatively large, and the vibration of the wind blows onto the blade is also large, so the clearance of the pitch bearing is required to be zero clearance or a slight negative clearance value, so that in the case of vibration lower the fretting wear of the bearing. The yaw bearing requires a small clearance value.

4.anti-corrosion treatment

Wind turbine equipment works in the field, and part of the yaw and pitch bearings are exposed to the outside and will be polluted by the atmosphere. The high humidity environment will also corrode the bearing base. Therefore, the yaw and pitch bearings exposed outside are eroded. The surface is required to be treated with anti-corrosion treatment, usually galvanized. Paint protection treatment is applied outside the galvanized layer as needed.

The slewing bearing of the wind turbine is an extra large bearing, which is mainly used for pitch and yaw systems. The load is complicated and the disassembly and maintenance is very difficult. Therefore, the design and manufacturing requirements of the wind power slewing bearing are strict. Due to its large size and difficult installation and disassembly, the maintenance is very difficult, and the failure of the slewing bearing will directly affect the working performance of the wind turbine and even cause downtime. Therefore, the wind power slewing bearing is required to have high reliability and long service life, and at least to reach the service life of the wind power generator, that is 20 years.

Causes and Troubleshooting of Crane Rotation Failure

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Crane is a common engineering machinery equipment. It is mainly used in the construction of bridges, roads, and port projects. Due to the working environment and overloading, there is often no turning action during work, which not only affects the overall performance of the equipment, It also delays work efficiency. Today, we mainly introduce the causes and troubleshooting methods of common crane rotation failures.

The crane does not rotate, mainly dues to the mechanical transmission of the slewing mechanism or its electronic control system fail. Today, we mainly discuss the non-rotational failures of tower cranes (Towers) and gantry cranes, analyze the causes of the failures, and propose ways to eliminate them.

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First, mechanical failure

The slewing bearing of the crane acts as a connection between the upper and the chassis in the slewing mechanism while supporting the entire rotating portion of the crane. The main cause of mechanical failure: slewing bearing wear. When the crane works in an environment with strong corrosiveness and dust, or after large rainwater has passed, the steel ball in the slewing bearing is damaged and the raceway is worn. Both will affect the work of the slewing mechanism. In severe cases, the slewing mechanism will experience heavy rotation and noise. Violation of the operation, such as lifting the weight, when using the basic arm of the crane to pull and tilt the heavy objects in the distance to achieve the purpose, often erroneously use the slewing mechanism to diagonally pull, this is a violation of the safe operating procedures. At the same time, the slewing mechanism and the basic arm are also damaged.

Remedy: Repair or replace the slewing ring bearing. Wipe in time, add a proper amount of lubricant to the inside of the slide, and apply some anti-rust oil to the outside. The grease nipple should be unblocked frequently to prevent clogging, and the tightness of the bolts everywhere should be checked frequently to prevent the gap between the upper and lower landslides from being too large due to the looseness of the bolts, resulting in wear of the steel balls and raceways.

Second, the rotary hydraulic system is low

When the pressure of the rotary hydraulic system is low, the sound and speed of the rotary process are normal under the condition of the no-load or light load of the crane; when it is heavy, there will be difficulty in turning or even no turning. The reason for this phenomenon is that the spring of the overload buffer valve of the rotary hydraulic system is softened. The pressure of the rotary hydraulic system is realized by adjusting the screw of the overload buffer valve. This adjustment screw also has the function of sealing the oil passage. In order to ensure the sealing of the oil passage, the screw must be tightened, but the spring cannot be adjusted at will. The pressure is gone. Remedy: When the spring pressure is not enough, only use the spring end to add a washer to solve or replace the new spring.

Third, the rotary electronic control system has failed

First, the rotary motor burns or the carbon brush breaks to produce a short circuit, and the carbon brush wears to cause an open circuit with the slip ring; the second is that the brake electromagnetic coil is burnt, causing the brake friction plate to lock and can not release the brake; the third is the electronic component The damage is broken or the fuse is blown; the fourth is the damage of the contactor that controls the rotation; the fifth is the damage of the relay that controls the rotation; the sixth is the poor contact of the electrical part of the main controller (the main switch).

Remedy: If the rotary motor burns, it is often caused by excessive load, phase loss of the three-phase power line or short circuit. If the slewing load is too large and the three-phase power line of the slewing motor is out of phase, the motor will be burnt. At this time, stop the operation immediately. Carbon brush breaks are prone to short circuits and high-quality carbon brushes should be used. The carbon brush should be maintained in time to replace the carbon brush with excessive wear. If the brake solenoid is burnt, check the solenoid. When checking, turn on the power of the electromagnetic coil to be inspected, and use a screwdriver to check whether the electromagnetic coil generates suction force to the screwdriver. If there is suction, it means that the electromagnetic coil is not broken, otherwise, the electromagnetic coil is broken, and the new electromagnetic coil should be replaced. Also, check the brake lining wear and replace if necessary. If the electronic component is damaged or its fuse is blown, replace the fuse in the electronic component or electronic component. If the contractor and relay that control the rotation are damaged, replace the new one. If the main controller of the swing is in poor contact, adjust or replace the contact or master controller assembly.

If there is a crane rotation failure during work, it should be stopped immediately to prevent the equipment from working, which not only affects the performance of the whole machine but also greatly reduces the life. Luoyang Hengguan Bearing Technology Co., Ltd. is a comprehensive enterprise integrating slewing bearing design, research, and development, production, sales, and service. If you have any other questions, please contact us.