Performance and application of diamond grinding wheel
Nov 14, 2019

Introduction : Superabrasive grinding wheels made of diamond or cubic boron nitride (CBN) abrasives have been widely used in all aspects of grinding because of their excellent grinding performance.

Diamond grinding wheel grinds high-hard and brittle material special tools such as cemented carbide, glass, ceramics and precious stones. In recent years, with the rapid development of high-speed grinding ultra-precision grinding technology, higher requirements have been placed on the grinding wheel. The ceramic resin bond grinding wheel can no longer meet the production needs. The metal bond grinding wheel has high bonding strength and good formability. Production has been widely used due to its long service life and other significant characteristics.

The metal bond diamond grinding wheel mainly has two types of sintering plating according to different manufacturing methods. In order to give full play to the role of super-hard abrasives, foreign countries began to develop a new type of grinding wheel by high-temperature brazing process from the early 1990s, namely single-layer high-temperature brazing super-hard abrasive grinding wheel. At present, this kind of grinding wheel is still in the research and development stage. Introduce for everyone

Sintered diamond wheel

The sintered metal bond grinding wheel is mostly made of a metal such as bronze as a bonding agent, and is manufactured by a high-temperature sintering method. The bonding strength is high, the formability is good, the high temperature resistance, the thermal conductivity and the wear resistance are good, the service life is long, and the load can be withstood. Because the grinding process of the grinding wheel inevitably has shrinkage and deformation, the grinding wheel must be shaped before use, but the dressing of the grinding wheel is difficult. At present, the common grinding wheel rolling method is not only time-consuming and labor-intensive, but also the diamond particles fall off during the dressing process. The dressing wheel itself consumes a lot and the shaping precision is low. Introduce for everyone

In recent years, scholars from various countries have successively carried out research work on the application of special processing methods to trim metal bond diamond grinding wheels, mainly including electrolytic dressing method and electric spark trimming method. The electrolytic dressing method is fast, but the shaping precision is not high; the electric spark dressing method has high precision, can be shaped and sharpened, but the shaping speed is slow; the composite dressing method has electrolytic sparking composite trimming method and mechanical chemical compound trimming method. Etc., the dressing effect is better, but the system is more complicated, so the problem of the finishing of the sintered diamond wheel is still not well solved.

In addition, because the grinding wheel manufacturing process determines the surface morphology is random, the geometry, distribution and cutting edge of each abrasive grain are inconsistent, so only a few high cutting edges are cut to the workpiece during grinding, which limits the grinding quality grinding. The efficiency is further improved.

Electroplated diamond wheel

Electroplated diamond wheel advantages:The electroplating process is simple, the investment is small, and the manufacturing is convenient;

2 no need to trim, easy to use;

3 single-layer structure determines that it can reach a very high working speed, currently abroad has reached 250 ~ 300m / s;

4 Although there is only a single layer of diamond, there is still enough life;

5 For the precision requirements of the roller wheel, the only manufacturing method for electroplating.

Due to these advantages, high-speed, ultra-high-speed grinding of electroplated grinding wheels occupies an undisputed dominant position. Electroplated diamond grinding wheel defects: there is no strong chemical metallurgical bonding between the plating metal and the substrate and the abrasive bonding surface. The abrasive is actually only embedded in the inlaid coating metal, so the holding force is small, the diamond particle load is heavy, and the grinding is easy to fall off. (or the coating is peeled off), resulting in overall failure; in order to increase the holding force, it is necessary to increase the thickness of the coating. As a result, the bareness of the abrasive grains is reduced, the grinding wheel is prone to blockage, the heat dissipation effect is poor, and the surface of the workpiece is prone to burns. At present, the domestic electroplated grinding wheel manufacturing has not yet achieved the optimal design of the grinding wheel according to the processing conditions. The inherent disadvantages of the single-layer electroplated diamond grinding wheel will inevitably limit its efficient grinding application. Introduce for everyone

Single layer brazed diamond wheel

In order to give full play to the role of diamond, it is necessary to increase the binding force of the bonding agent to the diamond and improve the bonding strength of the grinding wheel. The single-layer high-temperature brazing super-hard abrasive grinding wheel can overcome the shortcomings of the electroplating grinding wheel, and can realize the chemical metallurgical combination between the diamond, the bonding agent and the metal matrix, and has a high bonding strength, and only needs to maintain the bonding layer thickness to maintain the abrasive grain height by 20%. ~30% can hold high-load and high-speed high-efficiency grinding firmly to hold the abrasive grains, so that the exposed height of the brazing wheel can reach 70%-80%, thus increasing the chip space, the grinding wheel is not easy to block, and the abrasive utilization is more sufficient.

Under the same processing conditions as the electroplated grinding wheel, the single-layer high-temperature brazing super-hard abrasive grinding wheel has lower grinding force, power loss and lower grinding temperature, which means higher working speed can be achieved. This ultra-high speed grinding of300-500m/s or more It has special meaning. Single-layer high-temperature brazing non-coated diamond grinding wheel plus Cr silver-based solder single-layer brazing grinding wheel using high-frequency induction brazing method, using CrAg-Cu alloy as brazing filler metal, 780 °C air brazing for 35s, natural cooling, Achieve a strong connection between the diamond and the steel substrate. X-ray energy spectroscopy and X-ray diffraction analysis revealed that Cr3C2 was formed between Cr and diamond, and (FexCry)C was formed between the steel and the steel matrix. It was proved by comparison with the non-Cr solder that the alloy layer and diamond and steel were realized. The main factors of high bonding strength between the substrates are confirmed by grinding experiments. The diamond has a high holding strength.

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