1 The influence of the binder mainly includes the influence of the type and content of the binder
(1) Various resin bond The common feature of the diamond tool is that the heat resistance is poor. During the process of machining the workpiece, the heat generated between the diamond tool and the workpiece tends to make the local temperature too high. Once the critical value is reached, the resin is combined. The agent’s control of the diamond fails, and the diamond will fall off without being completely blunt, thus greatly increasing the processing cost. At present, the heat resistance of the resin binder is mainly improved by modifying the resin binder. The phenolic resin modified with a cyclyl ether can have a heat resistance of 180 ° C or higher. A new boron-containing silicon phenolic resin BSP synthesized from silicone prepolymer, boric acid, phenol and formaldehyde. BSP resin has excellent heat resistance and toughness due to the introduction of B-O bond and silicone chain in the phenolic resin structure. It also improves the water resistance and storage stability of the resin. A BMI (Bismaleimide) modified phenolic resin was used to obtain a bismaleimide modified phenolic resin having good heat resistance.
(2) Effect of resin binder content. The resin binder content has a large impact on the processing properties of the diamond tool. The literature introduces that in the single-crystal silicon wafer thinning grinding wheel, the resin binder content increases, the hardness and compressive strength of the grinding wheel gradually increase. When the resin binder content increases to a certain extent, the grinding wheel wear ratio tends to be slower. At the same time, the surface of the grinding wheel is prone to blockage, and the higher the content, the more serious the blockage phenomenon.
(3) Effect of particle size of resin binder. The particle size of the resin powder used in the production of diamond abrasives in China is mostly between 80 and 180 mesh. There are two defects in the particle size range. One is that it affects the press forming property of the abrasive tool, and the other is that it may affect the performance of the bonding agent. In the pressing process, the resin powder can be softened by heat and has certain fluidity to achieve the purpose of coating the abrasive grains. However, during the pressing process, the binder material is pressed in the mold, the space is limited, and the flow range of the resin is It is also limited. When the particle size of the resin powder is coarse, some of the abrasives are not firmly bonded, so that they fall off too quickly. Studies have shown that when the resin particle size is refined, the fluidity of the molding material can be improved, which is advantageous for hot press forming of the abrasive tool.
2 The influence of fillers mainly includes the influence of the type and content of fillers, etc.
Filler is an important part of diamond grinding tools. Adding proper amount of filler can not only greatly reduce the cost, but also improve the mechanical strength of the abrasive tool and prolong its service life.
There are many kinds of fillers, and the influence of adding different kinds of fillers on the abrasive tools is also different. According to their nature and use, they can be divided into four categories:
Inactive fillers. Used in plastic molding process, the purpose is to reduce the cost of abrasive tools;
Active filler. Plasticizing adsorption effect, the adhesion of abrasive particles and bonding agent is enhanced;
Reinforcing filler. Such as glass fiber, carbon fiber, etc., the purpose is to increase the strength of the bond;
Reduce the strength of the bond filler. Made of abrasive tools suitable for dressing tools.
In superhard material resin abrasives, its role is mainly to improve the heat resistance, hardness and strength of the bonding agent, and the ultimate goal is to improve durability. There are many types of fillers. For diamond resin abrasives, fillers for phenolic resin binders are commonly used in China as Cr2O3, ZnO and Cu powders; fillers for polyimide binders, except for Cu powder, when used abroad for dry grinding Zr, Co, CaCO3, etc. are added, and when used for wet grinding, ceramic materials such as quartz powder (SiO2) and aluminum oxide powder (Al2O3) may be added.
Studies have shown that the ratio of copper to tin in copper-tin alloy powder, content and particle size have a significant effect on the mechanical properties of resin-bonded superhard products. Only copper-tin alloy powder with appropriate copper-tin ratio, content and particle size can obtain excellent mechanical properties. Resin superhard product.
3 The impact of abrasive diamonds mainly includes the effects of diamond plating, type and particle size.
(1) After the metal surface of the diamond is plated with metal, the compressive strength of the single particles is improved, and the wear ratio is decreased, that is, the service life is prolonged. Compared with unplated diamond, the specific effects include the following aspects:
plating slows down the heat pulse of the resin bond. The thermal conductivity of the diamond coating is smaller than that of the diamond. Therefore, when the diamond abrasive particles contact the tool, the instantaneous high temperature generated is transferred to the resin after the plating, thereby protecting the resin immediately adjacent to the abrasive portion from high temperature. Damage;
coating improves the bonding strength of diamond and bonding agent, the metal coating contains diamond, the external and resin bonding agent can bond well;
coating improves the crushing strength of diamond particles, and the defects of diamond particles after plating metal are compensated, played a role Reinforcement, and the coating contains ductile metal, which is beneficial to improve the crushing strength of the particles; 44 coating protects the abrasive particles from isolation, and isolates the external oxygen and other harmful media. At the same time, the coating is on the diamond crystal. Graphitization can act as an inhibitor.
(2) Superhard materials manufacturers at home and abroad have classified the superhard abrasives in a fine manner. Among them, low-quality diamond abrasives or diamond abrasives with high self-sharpness and micro-crushing treatment by special processes are mainly used for resin bond diamond. Preparation of tools. Such as the PDA433, PDA321, PDA311, PDA211 and other diamonds provided by E6, it has high self-sharpness and micro-breaking. At present, RVD type diamond abrasives are commonly used in domestic resin molds. The particles are mostly needle-shaped, irregular in crystal form, low in strength, brittle, rough in surface but sharp in sharpening, and well combined with resin binders. Crystal CSD type diamond abrasives are used in resin bond abrasives to significantly increase the sharpness of resin diamond tools.
4 trimming the effect of resin bond diamond grinding wheel
The dressing process is an indispensable factor in the preparation of the grinding wheel. Through the shaping, the resin diamond grinding wheel of various shapes can be obtained, and the surface of the resin bond diamond grinding wheel is diamond-finished by the grinding wheel sharpening, and the proper trimming process directly affects the performance of the grinding wheel. Zou Dacheng designed a new resin bond diamond grinding wheel dressing method, and used white corundum, silicon carbide, boron carbide, molybdenum, molybdenum iron alloy and other methods to carry out grinding wheel dressing experiments respectively. By comparing and analyzing the dressing force and surface topography accuracy of various methods. , grinding wheel sharpening effect and grinding performance, in order to compare the dressing effect of different bonding methods on the resin bond diamond grinding wheel. The selection of dressing technology suitable for practical applications will help to improve the performance of the resin diamond wheel.