What is the bearing superfinishing process? Is bearing super precision important?
The ultra-precision process is not only used in the bearing industry, but also in the engine, and other precision machinery and instruments are also beginning to use this process.
What is the bearing super fine?
The superfinishing process of bearings is a kind of finishing processing method in which a feed motion is used to achieve micro-grinding.
The surface before superfinishing is generally precision turned and ground. Specifically, under good lubricating and cooling conditions, use a fine-grained abrasive (oil stone) to exert a small pressure on the workpiece, and in the vertical dry workpiece rotation direction, perform fast and short reciprocating oscillations on the workpiece rotating at a certain speed A light processing method for exercise.
What is the role of bearing super research?
In the manufacturing process of rolling bearings, superfinishing is the final process of bearing ring processing. It can reduce or eliminate the circular deviation left by grinding, repair the shape error of the groove, refine its surface roughness, and improve the physical and mechanical properties of the surface. , It plays an important role in reducing the vibration and noise of the bearing and improving the mission of the bearing.
Specifically, it can be reflected in the following three aspects
1. Can effectively reduce waviness. In the super-finishing process, in order to ensure that the whetstone always acts on the wave crest and not in contact with the trough, the arc of the whetstone in contact with the workpiece is greater than or equal to the wavelength of the surface waviness of the workpiece. In this way, the contact pressure of the wave crest is relatively large, and the convex peak is cut away, thereby reducing waviness.
2. Improve the groove shape error of the ball bearing raceway. Super-finishing can effectively improve the groove shape error of the raceway by about 30%.
3. It can generate compressive stress on the surface to be ultra-finishing. During the superfinishing process, cold plastic deformation mainly occurs, so that residual compressive stress is formed on the surface of the workpiece after superfinishing.
4. It can increase the contact area of the working surface of the ferrule. After super fine grinding, the contact support area of the working surface of the ferrule can be increased from 15% to 40% after grinding to 80% to 95%.
Bearing superfinishing process:
1. Cutting of bearings
When the grinding stone surface is in contact with the convex peak on the surface of the rough raceway, due to the small contact area, the force per unit area is relatively large. Part of the abrasive grains on the surface of the whetstone fell off and chipped, exposing some new sharp abrasive grains and edge. At the same time, the surface peaks of the bearing workpiece are subjected to rapid cutting, and the convex peaks and the grinding metamorphic layer on the surface of the bearing workpiece are removed through the action of cutting and reverse cutting. This stage is known as the stock removal stage, where most of the metal allowance is removed.
2. Half cutting of bearing
As the processing continues, the surface of the bearing workpiece is gradually smoothed. At this time, 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 grindstone are blocked, and the grindstone is in a half-cut state. This stage is called the semi-cutting stage of bearing finishing. In the semi-cutting stage, the cutting marks on the surface of the bearing workpiece become shallower and appear darker.
3. Finishing stage
This stage can be divided into two steps: one is the grinding transition stage; the other is the grinding stage after stopping cutting
Grinding transition phase:
The self-sharpening of the abrasive grains decreases, the edges of the abrasive grains are ground flat, and the chip oxides begin to embed into the pores of the oilstone. The abrasive powder blocks the pores of the oilstone, so that the abrasive grains can only cut weakly, accompanied by extrusion and polishing. At this time, the surface of the workpiece The roughness decreases quickly, and there are black swarf oxides attached to the surface of the oilstone.
Stop the cutting and grinding phase:
The friction between the oil stone and the workpiece is very smooth, the contact area is greatly increased, the pressure drops, and the abrasive particles can no longer penetrate the oil film to contact the workpiece. When the pressure of the oil film on the bearing surface is balanced with the pressure of the oil stone, the oil stone is floated. During the formation of oil film, at this time no cutting effect. This stage is unique to superfinishing.
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