An abrasive tool is a tool for grinding, grinding, and polishing.Most abrasives are artificial abrasives made from abrasives and binders.In addition to being widely used in machinery manufacturing and other metal processing industries, abrasive tools are also used in the grain processing, paper making industry and the processing of non-metal materials such as ceramics, glass, stone, plastics, rubber and wood.
In the process of using the abrasive tool, when the abrasive grain becomes blunt, the abrasive grain partially breaks or the binding agent breaks off, and the abrasive grain partially or completely falls off the abrasive tool, while the abrasive on the working surface of the abrasive tool constantly presents new cutting edge or new sharp abrasive grain, so that the abrasive tool can maintain the cutting performance for a certain period of time.This self - sharpness of abrasive tool is the outstanding feature of abrasive tool compared with general tools.
As early as the neolithic age, humans began to use natural grindstones to process tools such as stone knives, stone axes, bone tools, horns and teeth tools.In 1872, ceramic grinding wheels were developed in the United States by combining natural abrasive with clay.Around 1900, artificial abrasive materials came out and various kinds of abrasive tools were produced successively, creating conditions for the rapid development of grinding and grinding machines.Since then, the proportion of natural abrasives in the abrasives gradually decreased.
According to the source of raw materials, abrasives are natural and artificial.In the mechanical industry, only natural abrasive tools are used for oil stone.Artificial abrasives are divided into five categories, namely, grinding wheel, grinding head, whetstone, sand tile (hereinafter referred to as consolidation abrasive tools) and coated abrasives.In addition, in the habit of abrasives also listed as one of the abrasives.
According to the different abrasive materials used, the consolidated abrasive tools can be divided into ordinary and super-hard abrasive.The former is made of common abrasive like corundum and silicon carbide, while the latter is made of super-hard abrasive like diamond and cubic boron nitride.In addition, there are some special varieties, such as sintered corundum abrasive tools.
The ordinary abrasive consolidated abrasive tool is a kind of abrasive tool which is solidified into a certain shape by the binder and has a certain strength.Generally composed of abrasive, binders and pores, these three parts are often referred to as the three elements of a consolidated abrasive tool.
The abrasive material cuts in the tool.Binders are materials that bind loose abrasives to abrasives, both inorganic and organic.Inorganic binders include ceramics, bituminous bitumen and sodium silicate.Organic are resin, rubber and shellac.Among the most commonly used are ceramics, resins and rubber binders.
In grinding, the stomata can hold the chip and discharge the chip, and can contain the cooling fluid, which is helpful for the heat dissipation of grinding.In order to meet some special processing requirements, some filling agents, such as sulfur and paraffin, can be impregnated in the pores to improve the performance of grinding tools.This filler is also known as the fourth element of the abrasive tool.
The items that represent the characteristics of ordinary abrasive consolidated grinding tools are: shape, size, particle size, hardness, structure, down, gum and binder.The hardness of abrasive tool refers to the degree of difficulty of abrasive grain falling off the surface of abrasive tool under the action of external force.
The hardness of the abrasive tool mainly depends on the amount of the binder and the density of the abrasive tool.Conversely, high hardness.The hardness level is generally divided into 7 grades of super-soft, soft, medium soft, medium hard, hard and super-hard.The commonly used methods for measuring the hardness of abrasive tools include hand cone method, mechanical cone method, rockwell hardness tester method and sand-jet sclerometer method.
The hardness of the abrasive tool corresponds to the dynamic elastic modulus of the abrasive tool, which is helpful to measure the dynamic elastic modulus of the abrasive tool by audio method.In the grinding process, if the material hardness of the ground part is high, generally choose the tool with low hardness.On the contrary, use a tool with high hardness.
The structure of grinding tool is divided into compact, medium and loose.Each category can be further subdivided, and so on, with the organization number to distinguish.The larger the size, the smaller the volume percentage of abrasive in the grinding tool, the wider the clearance between abrasive grains, indicating the looser the structure.On the contrary, the smaller the number, the tighter the organization.It is difficult to be passivated when the loose structure is used, and the workpiece is less hot and deformed and burned during grinding.The abrasive particles of the closely organized abrasive tool are not easy to fall off, which is conducive to maintaining the geometric shape of the abrasive tool.The structure of the abrasive tool is controlled only in accordance with the formula of the abrasive tool at the time of manufacture.