Common superhard abrasive grinding wheel dressing methods

Superhard abrasive grinding wheel has excellent grinding performance and strong wear resistance, so it does not need to be trimmed often, but it is difficult to trim after initial installation and use of blunt grinding wheel. Especially in recent years, the wide application of superhard materials in production engineering and science and technology has made the application of superhard abrasive grinding wheels increase sharply, and thedressing problem of grinding wheelshas become increasingly acute, which has become an important research topic in the world. So far, many new dressing methods have been developed on the basis of the previous conventional dressing methods.

The dressing of superhard abrasive grinding wheel is usually divided into two processes: shaping and dressing. Shaping is the micro cutting of grinding wheel, so that the grinding wheel can achieve the required geometric shape accuracy and make the abrasive tip slightly broken, forming a sharp grinding edge. Dressing is to remove the binder between the abrasive particles, so that there is a certain amount of chip space between the abrasive particles, and make the grinding edge highlight the binder to form a cutting edge. For loose bonded superhard abrasive grinding wheels (such as ceramic bonded diamond or CBN grinding wheels), shaping and dressing can be carried out at the same time in one process, while for bonded densesuperhard abrasive grinding wheels(such as resin or metal bonded diamond grinding wheels, etc.), shaping and dressing must be carried out separately. Ceramic binder CBN (loose binder) grinding wheel can be repaired with single diamond or roller, which is easy to realize. This paper mainly introduces several shaping methods of dense superhard abrasive grinding wheel.

The main results are as follows:

(1)Diamond pen shaping methodis used to dressing resin bonded superhard abrasive grinding wheel, and the grinding wheel should rotate at low speed when dressing, otherwise the dressing effect is not good and the wear of diamond pen is faster. The grinding wheel surface modified by this method is smooth, the grinding performance is poor, and the shape and dimension accuracy is low, so the method is only used without other dressing conditions.When diamond grinding wheel is used as dressing tool to dressing resin bonded CBN grinding wheel, the dressing efficiency is very high, but the surface of the dressing sand is smooth, the number of particles per unit area is small, and the grinding ability is poor, so it can only be ground with small feed. Otherwise, the workpiece can be annealed easily during initial grinding. When dressing CBN wheel with corundum or silicon carbide grinding wheel, although the dressing efficiency is low, the grinding performance of the dressing wheel is good. The hardness and particle size of the dressing wheel have great influence on the dressing efficiency, dressing effect and grinding performance. The hardness and dressing efficiency of the dressing wheel are improved, but the grinding performance of the repaired wheel is reduced correspondingly, the surface of the grinding wheel is smooth and the grinding ratio is reduced. The particle size of dressing wheel has little effect on dressing efficiency and grinding performance of grinding wheel. When the particle size of the dressing wheel is close to the particle size of the repaired wheel, the grinding performance is better. The dressing conditions and grinding conditions are the same as above. From the above analysis, it can be seen that the characteristic parameters of the dressing wheel should be properly selected by grinding shaping method, otherwise the ideal dressing effect can not be achieved.

(2) theshaping grinding wheelused in rolling shaping method is green silicon carbide or white alumina ceramic bonded grinding wheel, and its particle size should be selected according to the particle size of superhard abrasive grinding wheel. If the particle size of superhard abrasive grinding wheel is fine, the finer dressing wheel should be selected. The dressing mechanism of rolling shaping method is different from that of diamond pen shaping method. The former mainly depends on pressure to break and fall off the abrasive particles, while the latter mainly depends on shear force. Because the rolling pressure is needed when the rolling shaping method is used, the rigid parts of the grinder are required to be good, otherwise the precision of the grinding wheel profile is low. When the dressing wheel presses the CBN wheel at a certain pressure, the shaping wheel rotates with the CBN wheel. In addition, the shaping grinding wheel also does back and forth movement, with a certain rolling pressure for dressing. The purpose of installing brake on shaping wheel shaft is to produce relative speed between shaping grinding wheel and CBN grinding wheel.

(3) soft steel grinding and dressing method uses soft steel grinding and shaping, but also can be trimmed. Because there are many abrasive particles falling off during shaping, it is not suitable to use this method to trim the grinding wheel with high precision. The grinding method of soft steel includes single roller method and double roller method, and its working principle is shown in Fig. 4 ≤ 44. The double roller method adopts two soft steel rollers, and the steering of the two rollers is the same, but the rotating speed is not equal. If the line speed of the dressing grinding wheel is Vsd, then the linear speed of one soft steel roller is Vsd V and the other is Vsd-V.. Therefore, there are two dressing forces of equal size and opposite direction in the tangent direction of the trimmed grinding wheel. In this way, the dressing grinding wheel will not produce additional disturbance torque, which can ensure the smooth shaping process and improve the shaping quality.