# Accuracy calculation method of planetary reducer

Updated:2022-10-19
Summary:Precision planetary reducer is a reducer widely used in the industry. Because of its high precision ...
Precision planetary reducer is a reducer widely used in the industry. Because of its high precision and low noise, it is generally used in precision transmission equipment, robots, laser cutting, lithium battery coating machines and other fields that require precision. There will also be more or less problems in the selection of planetary reducers. The accuracy of the most basic planetary reducer must be understood, so what is the calculation method of the accuracy of the planetary reducer? Let's find out together.
The accuracy of the planetary reducer refers to the return clearance. is the unit of arc minute. If a gear with r = 60mm is installed on the reducer, its return clearance is 3mm, and the deviation per revolution of the reducer is 0.05mm. The accuracy of the planetary reducer is generally 5 to 6 arc minutes, and the higher accuracy can reach 1 arc minute. The calculation method of the accuracy of the planetary reducer is as follows: when the input end is fixed and the output end rotates clockwise and counterclockwise, so that the output end generates 2% of the rated torque, the output of the reducer has a small angular displacement, which is the return clearance.
1arcmin is equal to (1/60). That is to say, if the return clearance is 1arcmin, the angular deviation of the output end is (1/60) for each revolution of the reducer. In practice, this angular deviation is related to the diameter of the output.
b = 2 π r α / 360
The specific calculation can be carried out according to the final precision requirements of the screw connected to the output end.
Since one set of planetary gears cannot meet the larger transmission ratio, sometimes two or three sets are needed to meet the user's requirements for the larger transmission ratio. As the number of planetary gears increases, the length of the 2- or 3-stage reducer will increase and the efficiency will decrease.
Planetary reducer accuracy measurement method:
1. Static measurement: Starting from the definition of the backlash of the planetary reducer, measuring the lag of the output end at the corner when the direction of motion can be changed in a static state. Mainly polyhedron method and hysteresis curve method.
2. Polyhedron method: measure the difference of planetary reducer with goniometer, autocollimator and polygon prism. The angle measuring device is installed on the input shaft, and the angle between the input shaft and the polyhedron fixed on the output shaft is collected by the acquisition card, so as to adjust the vertical polyhedron of the collimator and observe the observation and positioning of the polyhedron. When the input shaft is forward and reversed, the difference between the two limit angles divided by the transmission ratio is the output shaft hysteresis.
3. Dynamic measurement: refers to the dynamic continuous measurement of the side clearance of the planetary reducer when it is close to the working state of the planetary reducer. The main measurement method is the bidirectional transmission error method.

Common methods to improve the accuracy of planetary reducers:
1. Adjustment of the rotation accuracy of the planetary reducer spindle: Generally speaking, on the premise that the machining error of the spindle itself meets the requirements, the rotation accuracy of the planetary reducer spindle is largely determined by the bearing. The key to adjusting the rotation accuracy of the spindle is to adjust the clearance of the bearing. Maintaining a reasonable bearing clearance is of great significance to the working performance of the spindle components and the service life of the bearings. For rolling bearings, large clearance work will not only cause the load to concentrate on the rolling elements in the direction of stress, but also cause serious stress concentration at the contact between the inner and outer rings of the bearing, shorten the bearing life, and cause the spindle centerline to drift. Causes vibration of the spindle components. Therefore, the adjustment of the rolling bearing must be preloaded, so that a certain amount of interference is generated inside the bearing, so that a certain elastic deformation occurs at the contact between the rolling element and the inner and outer ring raceways, so as to improve the rigidity of the bearing.
2. Adjust the overall accuracy of the planetary reducer by adjusting the accuracy of the guide rail. In addition, if the guide rail gap is not suitable, it must be adjusted in time.
3. Clearance adjustment method: The planetary reducer will generate friction during the movement, which will change the size, shape and surface quality of the parts, causing wear and increasing the clearance between the parts. At this time, it is necessary to make reasonable adjustments to ensure the accuracy of the relative movement between the parts.
4. Error compensation method: through proper assembly, the errors of the parts themselves cancel each other out during the running-in period, thereby ensuring the accuracy of the equipment movement trajectory.
5. Comprehensive compensation method: Use the tool installed in the planetary reducer itself to process the correctly adjusted worktable and eliminate the comprehensive result of various precision errors. .
4. Hysteresis curve method: In industry, the hysteresis curve method is usually used to measure the clearance of planetary reducers. The geometrical clearance of the reducer is defined as: in the transmission chain, when 3% of the rated torque is used to overcome the internal friction and oil film resistance, and the parts are in good contact, due to geometric factors such as backlash, bearing clearance and other shaft angle errors, it is also called Clearance back to positive or clearance back to positive. During the measurement, lock one end of the reducer, load the rated torque on the other end, and then tilt to unload.
The above is the relevant knowledge about the accuracy calculation of the planetary reducer. The accuracy of the planetary reducer is one of the characteristics that distinguish it from other types of reducers. It is unmatched by other types in terms of accuracy characteristics. The high-precision planetary reducer can effectively improve Production quality and efficiency.

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