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Ultra precision technology is not only used in the bearing industry, but is also widely used in engines, and other precision machinery and instruments are also beginning to use this technology.
What is bearing ultra precision?
Bearing ultra precision machining is a finishing method that uses feed motion to achieve micro grinding.
The surface before ultra precision machining is generally subjected to precision turning and grinding. Specifically, it refers to a finishing method in which a fine-grained grinding tool (oilstone) is used to apply a small amount of pressure to the workpiece under good lubrication and cooling conditions, and a fast and short reciprocating oscillation motion is performed on the workpiece rotating at a certain speed in the direction perpendicular to the workpiece rotation.
What is the role of bearing ultra precision grinding?
In the manufacturing process of rolling bearings, ultra precision is the final process of bearing ring processing. It plays an important role in reducing or eliminating circular deviations left by grinding, repairing shape errors in grooves, refining surface roughness, improving surface physical and mechanical properties, reducing vibration and noise of bearings, and enhancing the mission of bearings.
Specifically, it can be reflected in the following three aspects:
1. Can effectively reduce waviness. In the process of ultra precision grinding, in order to ensure that the oilstone always acts on the wave peak and does not come into contact with the valley, the arc of the oilstone in contact with the workpiece is ≥ the wavelength of the surface waviness of the workpiece. As a result, the contact pressure of the wave peak is greater, and the convex peak is removed, thereby reducing the waviness.
2. Improve the groove error of ball bearing raceways. Ultra precision grinding can effectively improve the groove error of the raceway by about 30%.
3. Can generate compressive stress on the surface being ultra precision polished. During the ultra precision grinding process, cold plastic deformation is mainly generated, resulting in residual compressive stress on the surface of the workpiece after ultra precision grinding.
4. Can increase the contact area of the working surface of the collar. After ultra precision grinding, the contact support area of the working surface of the ring can increase from 15% to 40% after grinding to 80% to 95%.
Ultra precision process of bearings
1. Cutting of bearings
When the surface of the grinding stone comes into contact with the convex peaks on the rough raceway surface, due to the small contact area, the force per unit area is relatively large. Under a certain pressure, the grinding stone is first subjected to the "reverse cutting" effect of the bearing workpiece, causing some abrasive particles on the surface of the grinding stone to fall off and shatter, exposing some new sharp abrasive particles and edges.
At the same time, the surface protrusions of the bearing workpiece are subjected to rapid cutting, and the protrusions and grinding deterioration layer on the surface of the bearing workpiece are removed through the action of cutting and reverse cutting. This stage is called the cutting stage, in which most of the remaining metal is removed.
2. Half cutting of bearings
As the machining continues, the surface of the bearing workpiece is gradually ground flat. At this point, the contact area between the grinding stone and the workpiece surface increases, the pressure per unit area decreases, the cutting depth decreases, and the cutting ability weakens. At the same time, the pores on the surface of the grinding stone are blocked, and the grinding stone is in a semi cutting state. This stage is called the semi cutting stage of bearing precision machining, during which the cutting marks on the surface of the bearing workpiece become lighter and a darker luster appears.
3. Polishing stage
This stage can be divided into two steps: the first is the grinding transition stage; The second is the grinding stage after stopping cutting.
Grinding transition stage
The self sharpening of the abrasive particles decreases, the edges of the abrasive particles are smoothed out, and the oxide chips begin to embed into the gaps of the oil stone. The abrasive powder blocks the pores of the oil stone, causing the abrasive particles to only cut weakly, accompanied by squeezing and polishing. At this time, the surface roughness of the workpiece quickly decreases, and black oxide chips adhere to the surface of the oil stone.
Stop cutting and grinding stage
The friction between the oilstone and the workpiece is very smooth, the contact area greatly increases, the pressure decreases, and the abrasive particles can no longer penetrate the oil film and make contact with the workpiece. When the oil film pressure on the supporting surface is balanced with the oilstone pressure, the oilstone is lifted. During this time, an oil film is formed and no longer plays a cutting role. This stage is unique to ultra precision machining.
2024 April 3rd Week KYOCM Product Recommendation:
Rotary bearings consist of an inner ring and an outer ring, one of which usually contains a gear. Together with the connecting holes in the two rings, they enable optimized power transmission through simple and fast connections between adjacent machine parts. Bearing raceways are designed with rolling elements, cages or gaskets to accommodate loads acting individually or in combination in any direction.
Features and advantages:
High carrying capacity
High stiffness for rigid bearing applications
Low friction
Long service life
Surface protection and corrosion resistance
Integrate other features including:
Driving mechanism
Control device
Lubrication system
Monitoring system
Sealed cassette tape
https://www.kyocm.com/products/Slewing-Bearing/745.html
2024-05-15