What are the principles and characteristics of planetary gear reducers?- Shanghai SGR Heavy Industry Machinery Co., Ltd.

In the large family of reducers, planetary gear reducers are widely used in servo, stepper, DC and other transmission systems due to their small size, high transmission efficiency, wide reduction range, high precision and many other advantages. The function of a planetary gear reducer is to reduce the speed, increase the torque and reduce the load/motor moment of inertia ratio under the premise of ensuring precise transmission.

In the product system of SGR, one of the leading planetary gear reducer manufacturers,planetary gear reducer is also one of the "star products". The N series planetary gear reducer developed and produced by SGR uses 20CrMnTi carburized and quenched gear grinding, with multiple teeth to split the load, stable and reliable operation, high mechanical efficiency and other advantages. As early as 2009, the N series planetary gear reducer have won the "First Prize for Scientific and Technological Achievements in the Gear Industry" certificate from the China Gear Professional Association that year, and was also recognized as a "Shanghai High-tech Achievement Transformation Project", and obtained an invention patent.

(1) Transmission principle of the planetary gear reducer

The basic transmission structure of the planetary gear reducer is divided into 4 parts:

① Sun gear: located in the center of the planetary gear system, connected to the motor output shaft.

② Planetary gear: rotates around the sun gear, usually with multiple planetary gears to ensure even load distribution.

③ Planet carrier: supports the planetary gears, usually connected to the output shaft.

④ Outer ring gear: the planetary gears mesh with the outer ring gear to transmit power to the output shaft.

The driving source of the planetary gear reducer starts the sun gear by direct connection, and the sun gear drives the planetary gears assembled on the planetary gear carrier. The entire planetary gear system automatically rotates along the outer ring gear, and the planetary carrier connects the output shaft to achieve the purpose of deceleration. A higher reduction ratio requires multiple sets of stage gears and planetary gears to be multiplied and accumulated.

(2) Deceleration characteristics of planetary gear reducers

a. High torque, strong load: Compared with traditional parallel gear transmission,the planetary gear reducer has the advantages of high torque and compact structure. Traditional gears are driven by extrusion of very few point contact surfaces between two gears, and all loads are concentrated on very few gear contact surfaces, which easily causes friction and fracture between gears. Planetary gear reducer has multiple larger areas and 360-degree uniform load on gear contact surfaces. Multiple gear surfaces evenly bear instantaneous impact loads together, making it more able to withstand the impact of higher torque, and the body and bearing parts will not be damaged or broken due to high loads.

b. Compact structure and small size: Compared with traditional gear reducers, planetary gear reducers have the advantages of compact structure and small size; the reduction ratio of traditional gear reducers must be generated by the multiple value of the number of gears, and there is a certain spacing between the large and small gears, so the gearbox has a large space to accommodate! To achieve a high reduction ratio, it is necessary to connect and combine more than two reduction gearboxes, resulting in a very large volume and weight. The structure of the planetary gear reducer can be repeatedly connected according to the required number of sections, and multiple sections can be combined separately. The planetary gear reducer has a compact structure, small size, light weight, and light appearance, and its application scenarios are more diverse.

c. High efficiency and low noise: Compared with traditional gear reducers, planetary gear reducers have the advantages of high efficiency and low noise; the planetary gear combination has a unique multi-point uniform fit, and the arc-enveloping structure of the outer gear ring makes the outer gear ring and the planetary gear closely combined, and the gears have a high degree of fit. In addition to improving the efficiency of the planetary gear reducer, the design itself can achieve high-precise positioning. In addition, by meshing multiple planetary gears with the outer gear ring at the same time, the planetary gear reducer reduces the load of a single gear, thereby reducing noise.

(3) Mechanical parameters of SGR's N series planetary gear reducer

The mechanical parameters of the N series planetary gear reducers developed and produced by SGR are as follows:

· Ring gear specifications: 200~885mm

· Output torque range: T2≤540000N.m

· Speed ratio: i ≥3

·Modular design, serialized specifications, and specialized production

· The input end has round holes, spline holes, round shafts, internal or external spline shafts, additional flanges, brakes, etc., The N series planetary gear reducers are suitable for hydraulic motors or electromagnetic motors, etc.;

· The output end type has round shafts, hollow shafts, hollow shafts with expansion disks, internal or external spline shafts, additional connecting plates, gears, flanges, etc.;

· There are many matching accessories, such as cooling and lubrication devices, check valves, etc., and users can choose matching accessories according to their needs.

In addition, the product positioning of SGR's N series planetary gear reducer is: "Replacing imported similar reducers" (it can be replaced with similar products of brands such as Brevni, Dynamic, Rossi, Bonfilioli, etc.). The design concept and production technology are synchronized with some European countries. Due to localized services, it has been recognized by users in industrial fields such as construction machinery, ship auxiliary machinery, mining machinery, textile printing and dyeing machinery with good cost performance. (Author: SGR,Angie Zhang)

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