What is the slewing ring gear module?

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Slewing bearing is one of the important parts of many modern machinery and equipment. It is called “joint of machine”. Many people are familiar with various parameters of slewing bearing, including clearance, inner and outer diameter, friction coefficient, etc. Many friends don’t know the module of supporting gear. The technical staff of Longda Bearing, a slewing bearing manufacturer, will give us a detailed introduction to this problem.

1. What is the module of slewing ring gear

The length of the arc (gear)/straight line (rack) occupied by a single gear tooth in the indexing circle (gear)/or line (rack), its length is π * m, and m is the modulus.

What does the module of the slewing ring represent: The module of the slewing ring represents the product of the tooth pitch and the number of teeth of the slewing ring gear, which is the circumference of the index circle. The gear modulus of the slewing ring determines the size of the tooth. The gear modulus is a basic parameter for the calculation of the gear size. The symbol is “m”. Gear cutters can be standardized, so that the standard modulus of gears can be standardized for mass production. Facilitate the replacement of later accessories. In the same way, “modulus” refers to the ratio of the pitch t between the tooth profiles of two adjacent gear teeth on the same side and the circumference ratio π (m=t/π), in millimeters.

If the number of teeth of the slewing ring gear is constant, the larger the gear modulus, the larger the radial dimension of the gear. The teeth of a gear with a large modulus are thick, and for two gears with the same number of teeth, the outer circle of the gear with a large modulus is larger. Therefore, the modulus of the gear in a watch is very small, and the modulus of the flywheel and transmission gear on the mechanical punching machine is large. The modulus of the two meshing gears must be the same. Modulus is the basic parameter of gear design, and it is used in many calculations of gear design.

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2. Reasonable selection of gear module

When designing a gear, one of the important parameters is this modulus. The gnawing of the gear will produce gnawing pulsation. The main reason is that it has a great relationship with the elastic deformation of the gear teeth. It is a basic part of the gear design. Parameter-gear modulus, if it is a relatively large modulus (that is, a gear with a relatively large size), it will also have a relatively large load-bearing capacity. The modulus parameter is inversely proportional to the degree of bending of the gear teeth. The increase of the modulus means that the rigidity of the gear teeth is improved, so that the elastic deformation of the gear teeth will not be great when the gnawing transmission is carried out, which greatly reduces the impact force formed by the gear teeth, thereby achieving The purpose is always greatly reduced. Therefore, from this point of view, the modulus should be increased appropriately, but the error generated when machining gears is also related to the modulus. If the modulus is increased, the tooth profile and pitch will also be increased. At this time, the error of gnawing noise will also increase accordingly, so the choice of modulus should be determined according to the specific situation.

Slewing Bearings

In the case of keeping the modulus unchanged, the diameter of the gear is proportional to the number of teeth, so the change of the number of teeth will also change the bending amount and elastic rigidity of the gear teeth: the strength of the noise generated by the sound source is not only related to the energy of the vibration source It is related to the size of the radiation area. If the radiation area is increased, the radiation power will also increase. Increasing the gear diameter will increase the noise radiation area, which will greatly affect the gear. Effective control of noise.

Therefore, in the relevant design, within the permissible range of ensuring the strength of the gear, the number of small teeth and the small modulus should be used as much as possible, and the reasonable selection of materials and heat treatment methods can be combined to promote the increase of the strength of the gear teeth, thereby reducing the diameter of the gear teeth. Then, the purpose of reducing gear noise is achieved.

What is the gear making process of slewing bearings

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Gear processing is a time-consuming process in the production of slewing bearings, and it is also one of the main factors that have restricted the production efficiency of slewing bearings. Based on the actual machining data, the application of milling and hobbing processes in the processing of turntable bearing teeth is compared from the aspects of efficiency and cost, which provides a basis for the reasonable selection of turntable bearing teeth processing technology and equipment. Today, the editor will come to talk with you about the tooth-making process of slewing bearings.

1. Material selection of slewing bearing blank

Generally, 50Mn is used for the slewing bearing ring. After surface quenching, the raceway hardness is HRC55-62. However, sometimes 42CrMo is selected to meet the needs of the host for special applications, which has a higher hardness. LDB’s selection of blank suppliers has undergone strict screening and strictly follows the traceability procedure. For each blank, from receipt to finished product, it can trace the source of the blank according to its serial number, quality inspection and other whole-process data.

Slewing Bearings

2. The technology of making gears from slewing bearings

1. The equipment used in the gear processing department still uses a large number of ordinary gear hobbing machines and gear shaping machines. Although it is convenient to adjust and maintain, the production efficiency is low. If a large capacity is completed, multiple machines are required to produce at the same time. In order to solve the problem of low processing efficiency, while increasing the number of gear hobbing machines and gear shapers, high-speed gear milling machines are used, which has high processing efficiency and good surface finish quality.

2. Some slewing bearings used under severe conditions require surface quenching treatment, such as excavators, pile drivers, wood grabs, graders and other operating conditions, which have relatively large impact loads and require quenching treatment on the tooth surface. The hardness after quenching of several sizes is between 45-60HRC. For common working conditions such as cranes and tower cranes, the tooth surface does not need to be heat treated.

3. With the rapid development of Industry 4.0, slewing bearings are more and more widely used in the automation industry. In this application field, the accuracy requirements for the teeth are relatively high, and the low requirements are also 8 levels of accuracy. In response to the rapid changes in the market, during the construction of the new plant, higher accuracy requirements are required for the equipment to meet the market demand.

4. After the tooth-making process is completed, there are follow-up processes such as fine turning, plane, drilling, track grinding, and assembly, and the slewing bearing can be shipped out of the factory.

3. Introduction to the failure analysis of the slewing bearing gear

1. Improper adjustment of the backlash of the large and small gears during installation, which did not meet the requirements, resulting in poor meshing of the two gears during operation, resulting in broken teeth. The backlash should be adjusted strictly as required.

2. Failure to adjust the meshing gap with the pinion at the maximum position of the gear jump as required, causing the pinion to jam when meshing with the maximum gear jump position during operation, causing tooth breakage. The meshing adjustment should be carried out at the position painted with green paint and the pinion gear should be adjusted according to the requirements for trial operation.

3. The axes of the large and small gears are not parallel, and the large and small gears mesh poorly after installation, causing tooth breakage. It should be ensured that the axes of the two gears are parallel.

4. The mounting bolts are not fastened tightly, and the gears of large and small meshes are not well meshed, causing gear breakage. The bolts should be tightened as required.