Characteristics of vitrified CBN grinding wheel

cubic boron nitride Nitride, CBN) is second only to diamond in hardness. It has the characteristics of high hardness, good thermal stability and chemical stability, and is chemically inert to iron group elements at high temperature. It is an ideal material for processing iron group materials. The cubic boron nitride abrasive tool is a series of tools for grinding, grinding and polishing with certain shape and performance made under certain conditions with CBN as abrasive, with the help of binder and other auxiliary materials. Such as grinding wheels, grinding heads, cutting discs, grinding discs, oil stones, etc. Among them, CBN grinding wheels are the most common. According to the bonding agent, CBN grinding wheel has three types: metal bond CBN grinding wheel, resin bond CBN grinding wheel and ceramic bond CBN grinding wheel. Compared with other binders, although vitrified binders have disadvantages such as high brittleness and long production cycle, they are widely used in CBN grinding wheel systems due to their advantages of good heat resistance, good shape retention, many and adjustable pores, and easy dressing. The proportion of CBN abrasives has increased year by year, becoming the largest family of CBN abrasives.

Compared with other bond CBN grinding wheels, vitrified CBN grinding wheels have the following characteristics:

(1) It has a controllable porosity. The pores on the surface of the vitrified CBN grinding wheel have the functions of chip containment, chip removal, enhanced heat dissipation and cooling. According to the purpose of grinding, the size and number of pores in the vitrified bond CBN grinding wheel can be adjusted by studying the vitrified bond and adjusting the formula of the grinding wheel.

(2) Good cutting performance. Due to the open structure of the vitrified CBN grinding wheel, the CBN abrasive grains can be optimally exposed and protruded, and the resulting grinding wheel has excellent free cutting performance and high workpiece material removal rate. Low energy and good grinding performance.

(3) Good thermal stability and chemical stability. In the ceramic bond CBN grinding wheel, on the one hand, the ceramic bond has good heat resistance, which can make full use of the high thermal stability of the CBN abrasive, and the abrasive tool has a long service life; on the other hand, the excellent chemical stability of the ceramic bond, It makes the abrasive tool have a wider range of adaptation to the grinding fluid.

(4) Good rigidity. Due to its small thermal expansion coefficient and good rigidity, the vitrified bond CBN grinding wheel makes the knife small when grinding, and is more suitable for high-precision and low-roughness grinding.

(5) Good self-sharpening. The vitrified bond CBN grinding wheel is easy to dress due to its good self-sharpening, long dressing interval and low dressing frequency; correction and sharpening can be completed at one time, and the maintenance cost is low.

(6) The integrity of the workpiece is good. The surface integrity of the workpiece ground by the vitrified bond CBN grinding wheel is good, the quality of the workpiece is high, and the service life of the grinding wheel is long.

From the perspective of macroscopic composition, the ceramic bond CBN grinding wheel belongs to a multi-component ceramic matrix composite material composed of CBN abrasives, auxiliary abrasives, binders and other materials. During the preparation of the grinding wheel, the following points should be noted:

(1) The ceramic bond should match the thermal expansion coefficient between the CBN abrasive and the auxiliary abrasive to ensure a firm bond between them.

(2) There should be no obvious chemical reaction between the ceramic bond and the CBN abrasive, so as to avoid the damage of the surface structure of the CBN abrasive and the deterioration of the main properties such as hardness.

(3) Under the preparation conditions of the grinding wheel, the performance of the CBN abrasive and the main materials cannot be degraded.

(4) It is necessary to reasonably select the type, particle size, concentration and grinding wheel hardness of the CBN abrasive according to the performance of the grinding workpiece material (such as material, hardness, etc.), processing method, machining allowance, machining accuracy requirements and other factors to adapt to specific grinding requirements.

The superior performance of vitrified bond CBN grinding wheel has made it used in many manufacturing fields such as automobiles, aviation, machine tools, bearings, engineering ceramics, etc., and the high thermal conductivity of vitrified bond makes it suitable for high-speed and high-efficiency grinding. potential. With the continuous emergence and popularization and application of high-end grinding equipment, the application of vitrified CBN grinding wheels in various types of grinding such as forming, high-efficiency and high-precision grinding will become more and more, and the application fields will become more and more extensive.