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Shanghai Shang Shaft Bearing Quality Inspection Institute Co., Ltd.

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Address: 301 Shangxue Road, Jiading District, Shanghai

Bearing Manufacturing Technology -- Processing of Steel Ball

2021-05-26 14:57

As a key part of rolling bearings, steel balls are used in bearings.The role of carrying and transmitting load and motion, and the life of the bearingAnd vibration noise has a greater impact.

 

Any point on the surface of the steel ball is loadedWorking face, subject to variable load with variable period, small contact area, connectionLarge contact stress, steel ball stress conditions are relatively bad, easy to produce fatigueDestruction. The entire surface of the steel ball is both the processing surface and the bearing surface, because.This steel ball processing technology is also very unique and specialized in the machinery industry.of raw materials, process technology, processing equipment, tooling, grinding tools, research and development.Grinding fluid and other requirements are very high.

 

At present, the domestic steel ball technology level, equipment level, quality control level and tooling level have reached or close to the international advanced level, management is more sophisticated and perfect, large-scale production and operation highlights, the total production continues to expand. Steel ball quality level: mass production tolerance grade G5, complete specifications and materials, single particle vibration up to 26 dB, lifeKThe value reaches (basic rating life test value L10t and basic rating lifeL10ratio) above 12.

1) Processing process

2 main processing methods:

2) Raw materials

GCr15 wire dueModerate price, easy heat treatment, the most application.extensive,More than 85%. Others, such as the use of stainless steel balls in situations where corrosion resistance is more important than durability;Aircraft and other special purposes, requiring the use of excellentIn the heat resistance of GCr15High-speed tool steel (tungsten steel) andHeat resistant steel (M50)etc, special purpose steel balls usuallyDue to the implementation of complex heat treatment processes (such as high temperature quenching.Fire, many times backfire, cold treatment, etc.) materialsThe cost is higher and the processing cost is higher.

3) Process equipment

Domestic has formed a set of main steel ball processing technologyEquipment, including Z32,Z32G series steel ball cold heading machine and high-speed cold headingMachine, 3M49,3M79 series light ball machine, 3M46,3M76 series millBall machine, 3M47,3M77 series ball grinding machine, protective atmosphere heat treatmentFurnace, steel ball surface strengthening machine, based on brush cleaning and based on high strengthSpongy rotating extrusion cleaning machine, etc. Testing equipment is mainlyVisual system-based steel ball surface quality appearance inspection instrument, based onEddy current testing principle with optical, vibration channel of eddy current photoelectric outsideThe inspection instrument. The diameter of the grinding plate of the main processing machine tool for light, grinding and grinding isφ300~950(1000)mm,Ball loading quantity 20~1000kg, machine toolThe machining accuracy can meet the requirements of G5 steel ball.

 

 

Issues that need to be paid attention to: 1. Domestic high-speed cold heading machineThe quality is still not stable, the reliability is poor, and the quality of the cold heading die is low; 2. Light, grinding and research equipment is generally general-purpose equipment, dedicated professional.There are many improvements in layout design, and efficiency still needs to be continuously improved.;(3) Automatic control and automation of light, grinding and research equipmentThe level needs to be further improved; (4) the steel ball processing processBetween cleaning, drying, quality control connection equipment is still lack of professional layout and.Production;(5) steel ball finished product cleaning equipment applicability and reliable cleaningsex needs to be improved;(6) the finished appearance inspection instrument for steel balls still needs to be improved,Increased reliability.

 

4) Quality control methods

Domestic steel ball quality control has formed a set of squareThe quality indicators and methods are mainly: raw material quality, size andDimensional accuracy, heat treatment hardness and metallographic structure, surface defects. WithWith the improvement of steel ball processing technology and processing equipment, the steel ball manufacturingEnterprises in the size and dimensional accuracy, heat treatment hardness and other aspects of the basicAll can meet the standard requirements. Issues that need to be paid attention to: 1.Raw material quality control and material selection according to the purpose of the steel ball;2. Dimensional stability detection and control of steel ball; 3. Strong surface of steel ballSurface stress control; 4. Detection and control of steel ball surface morphology5. Steel ball surface waviness monitoring and control; 6. Steel ball outGoods quality confirmation; 7. steel ball contact fatigue life test and control.

5) Contact fatigue failure

The mechanism of rolling fatigue is roughly divided into internal origin type peelingFallingwithSurface type-of-origin spallingTwo categories. The internal origin spalling is mainly caused by the non-metallic inclusions under the rolling contact surface becoming the origin, which needs to be dealt with by improving the purity of raw materials. The surface origin type spalling is directly related to the use environment, lubrication state, and surface state (surface roughness and scars on the rolling surface) of the rolling bearing. It has a shorter life than the internal origin type spalling, and the bearing damage accounts for a larger proportion.The coping strategy of surface origin type peeling, such as the carbon-nitrogen co-penetration treatment on the surface of GCr15 steel ball, is more important because of the high cost of carbon-nitrogen co-penetration treatment.The use of ordinary overall quenching to improve the surface hardness of the steel ball, so that the indentation is difficult to form, improve the durability of the environment in the presence of foreign matter.

6) Summary

Steel balls still need to further improve quality as the primary objectivestandard, using reasonableEvaluation method of material purity, fromThe blanks begin to be carried out thoroughlyQuality Management, at the same time, from preventingIn terms of non-conforming products leaving the factory, the development is moreHigh-function automaticappearance inspection instrumentis essential. In addition, to improveDurability, steel mills are required to further improve material purityAt the same time, the development of steel balls adapted to the applicationHeat treatmentTechnologyetc., giving the traditional GCr15 steel ball a variety of additionalValue.

 

In recent years, with the increasing diversification of the demand for bearing applications, high speed, high temperature and other application conditions, the use of ceramic balls (such as Si3N4Ball) to replace the steel ball of the new material ball, the current production upward trend is very fast, the application demand is strong, but to solve the problem of high price.