High speed grinding belongs to the current manufacturing method in machining technology. Compared with ordinary grinding, it has great advantages. It not only increases the grinding speed, but also improves the production efficiency. The combination of finish machining can better achieve the metal grinding rate comparable to other cutting processes. So, what are the grinding methods for machining?
1、 Ultra high speed grinding
Grinding with a grinding speed of more than 150m/s is called ultra-high speed grinding. Ultra high speed grinding can greatly improve the grinding efficiency, prolong the service life of the grinding wheel and reduce the roughness value of the machined surface. It can realize the ductile domain grinding of hard and brittle materials, and also has a good effect on high plasticity and difficult to grind materials.
On the ultra-high speed cylindrical grinder, the blank can be directly ground into a crankshaft, and 2kg metal can be removed per minute. At ordinary grinding speed, the grinding force increases rapidly with the increase of grinding rate when grinding nickel base superalloy. Due to the limitation of grinding wheel wear and thermal damage, nickel base alloy can only be ground under the condition of low grinding rate. However, at a grinding speed greater than 140m/s, the grinding force increases little with the increase of grinding rate, so the feed speed can be increased by 60 times (the feed speed of ordinary grinding is not more than 1m/s), and the grinding rate is greatly improved without thermal damage.
Foreign countries have developed ultra-high speed grinding wheels with a grinding speed of 500m/s in the laboratory. The grinding speed of ceramic bonded CBN wheel can reach 160m / s. Diamond rollers can be used for shaping grinding, and the grinding surface accuracy can reach ± 0.005mm; The steel wheel body is electroplated with CBN grinding wheel, and the grinding speed is 80-200m/s; The material removal rate of single-layer high-temperature brazed CBN grinding wheel is higher than that of electroplated CBN grinding wheel. The grinding wheel has small wear and long service life, and the grinding speed can reach more than 300m / s; Cast iron based diamond micro powder grinding wheel, which can be shaped by electrolytic on-line dressing method, is suitable for ultra-high speed precision grinding of hard and brittle non-metallic materials such as glass and ceramics.
2、 High speed point grinding
High speed point grinding is to form a small inclination angle between the axis of the grinding wheel and the axis of the workpiece in the horizontal plane, so that the grinding wheel and the workpiece become point contact in theory, which not only reduces the area of the grinding contact area, but also eliminates the grinding closed area, which is conducive to the injection of grinding fluid into the grinding area. Because the grinding contact area is small, the cutting force is also reduced, which reduces the possibility of grinding vibration and makes grinding more stable.
The loss of grinding efficiency in high-speed point grinding due to the reduction of grinding contact area is compensated by the increased grinding speed. Improving the grinding speed can make full use of the high hardness and high wear resistance of superhard abrasive. At present, the grinding speed in use has reached 120-180m / s. As the grinding speed increases, the cutting thickness of each abrasive grain decreases, which reduces the load on the abrasive grain, is conducive to chip removal, and improves the service life of the grinding wheel. Due to the great improvement of grinding speed, a large amount of heat during grinding cannot be transmitted to the grinding wheel and workpiece and is taken away by chips. It is a kind of cold grinding, which improves the surface quality of machined parts.
High speed point grinding also reduces the thickness of the grinding wheel due to the reduction of the grinding contact area, which reduces the price of the grinding wheel and the cost of wheel dressing. Thinning the thickness of the grinding wheel reduces the weight of the grinding wheel, and is also conducive to the uniformity of the quality of the grinding wheel and the balance of the grinding wheel.