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The super precision process of the bearings

wallpapers News 2020-12-15
The super-precision process of the bearings is a kind of feed motion to achieve a finishing method of micro-grinding.
 
The surface before superfinishing is generally precision turned and ground. Specifically, under good lubrication and cooling conditions, a fine-grained abrasive tool (whetstone) is used to apply small pressure to the workpiece, and in the direction of the vertical dry workpiece rotation, the workpiece rotating at a certain speed is fast and short reciprocating oscillation A sports finishing method.
1. Cutting of the bearing
 
When the surface of the grindstone is in contact with the convex peaks of the rough raceway surface, due to the small contact area, the force per unit area is greater. Under certain pressure, the grindstone is first subjected to the "back cutting" action of the bearing workpiece, so Part of the abrasive grains on the surface of the grindstone fell off and shattered, exposing some new sharp abrasive grains and edges. At the same time, the surface convex peaks of the bearing workpiece are subjected to rapid cutting, and the convex peaks and the ground 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, and most of the metal margin is removed at this stage.
 
2. Half cutting of bearing
 
As the processing continues, the surface of the bearing workpiece is gradually ground. 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 decreases. At the same time, the pores on the surface of the grindstone are blocked, and the grindstone is in a half-cutting state. This stage is called the half-cutting stage of bearing finishing. In the half-cutting stage, the cutting marks on the surface of the bearing workpiece become lighter and appear darker gloss.
 
3. Smoothing 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 stage:
 
Abrasive particles are reduced by self-sharpening, the edge of the abrasive particles is smoothed, and the oxides of the cutting chips begin to be embedded in the whetstone gaps. The abrasive particles block the pores of the whetstone so that the abrasive particles can only be cut weakly, accompanied by squeezing and polishing. The roughness decreases quickly, and black chip oxides adhere to the surface of the whetstone.
 
Stop cutting and grinding stage:
 
The friction between the oil stone and the workpiece is very smooth, the contact area is greatly increased, and the pressure drops. The abrasive particles can no longer penetrate the oil film and contact the workpiece. When the oil film pressure on the bearing surface is balanced with the oil stone pressure, the oil stone is floated. During the formation of an oil film, the cutting effect is no longer available at this time. This stage is unique to superfinishing.

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