In the grinding process, under the action of friction and extrusion, the edges and corners of the grinding wheel gradually become round and blunt, or when grinding ductile materials, grinding chips are often embedded in the pores on the surface of the grinding wheel, which makes the surface of the grinding wheel blocked and eventually makes the grinding wheel lose its cutting ability. At this time, there will be slippage between the grinding wheel and the workpiece, which may produce vibration and noise, reducing grinding efficiency and surface roughness. At the same time, due to the increase of grinding force and grinding heat, the workpiece will be deformed, which will affect the grinding accuracy, and even cause grinding surface burns and small cracks in serious cases. In addition, due to the uneven hardness of the grinding wheel, different working conditions of abrasive particles, uneven wear on the working surface of the grinding wheel and abrasive particles falling off at different parts, the external viscosity of the grinding wheel is lost, which affects the shape accuracy and surface roughness of the workpiece surface.

Dressing method of grinding wheel:

Grinding wheel dressing generally includes turning, using diamond rollers, grinding and rolling.

① Turning dressing method: Turning grinding wheel with single diamond (or diamond pen and diamond dressing block made of finely divided diamond) is the most common dressing method (Figure 1). The diamond tools installed on the tool rest are usually inclined about 5 ~15 in the vertical and horizontal directions respectively. The contact point between diamond and grinding wheel should be 0.5 ~ 2mm lower than the axis of grinding wheel, and the diamond should move at low speed and uniform speed during dressing. It is required that the smaller the surface roughness after grinding, the lower the feed speed. To achieve the surface roughness of Ra 0. 16 ~ 0.04 micron, the dressing feed rate should be less than 50 mm/min. The total trimming amount is generally about 0. 1 mm on one side, and the trimming is repeated. The primary cutting depth of rough cutting is 0.0 1 ~ 0.03mm, and the fine cutting is less than 0.01mm.

(2) Dressing method of diamond roller: A large number of diamond particles are embedded in the surface of steel roller by electroplating or powder metallurgy, and the diamond roller is made by rotating at a certain speed (to reduce the relative speed between roller and grinding wheel), and the surface of high-speed rotating grinding wheel is ground and rolled, so that the grinding wheel can obtain a sharp working surface consistent with the contour of the roller. The diamond roller is complex and expensive to manufacture, but it is durable and has high dressing efficiency. Suitable for dressing and grinding special shaped surfaces (such as threads, gears and turbine blade tenons) in batch production.

(3) Grinding wheel dressing method: dressing with superhard silicon carbide grinding wheel rotating at low speed and grinding wheel rotating at high speed.

(4) Rolling dressing method: using cemented carbide disks, a group of rollers sleeved by corrugated white iron disks or grooved hardened steel plates are rolled and dressed with grinding wheels. Generally, the roller is mounted on the dressing fixture and operated manually, which has high dressing efficiency and is suitable for dressing coarse grinding wheels.