Is for abrasive grinding, grinding and polishing tools. Most of the abrasive is made of abrasive plus artificial abrasive binding agent, is also useful natural mineral rock directly processed into natural abrasive. In addition to grinding and other metal processing machinery manufacturing industry has been widely used, but also for food processing, paper industry and the ceramics, glass, stone, plastic, rubber, wood and other non-metal materials processing.
Abrasive in use, when the blunt abrasive, because the abrasive agent or a combination of its own to break fracture, the abrasive grain from the partial or complete loss, the working surface of the abrasive grinding emerging new cutting edge, sharp or continuously exposing new abrasive grains, the abrasive can be maintained within a certain time cutting. This self-sharpening abrasive is abrasive tool compared with the general prominent feature.
As early as the Neolithic Age, humans had already started to process the application of natural stone knives, stone axes, bone, horn, and tools such as a tooth; 1872, appeared in the United States with natural abrasives combined with clay firing ceramic grinding wheel; 1900 years ago, the advent of artificial abrasives, using artificial abrasives manufacturing have produced a variety of abrasives for grinding and grinding create the conditions for rapid development. Since then, natural abrasive in the abrasive proportion gradually reduced.
Abrasives source of their raw materials, with natural and artificial abrasive abrasive categories. Commonly used in machinery industry is only natural abrasive Whetstone. Artificial abrasive characteristics according to the basic shape and structure of the distinction between a grinding wheel, grinding, stone, sand tile (the foregoing collectively referred abrasive) and coated abrasives five. In addition, it is customary also put abrasives abrasive as a class.
Bonded Abrasives are used by different abrasives can be divided into ordinary abrasive abrasive and superabrasive abrasive. The former corundum and silicon carbide and other common abrasive, the latter with diamond and cubic boron nitride and other superhard abrasive material. In addition, there are some special varieties, such as sintered corundum abrasive and so on.
By ordinary abrasive abrasive abrasive solid binding agent to form a certain shape common, and has a certain strength abrasive. Generally abrasive, binder and pore structure, these three parts are frequently referred to as the three elements of abrasive.
Abrasive abrasive cutting action play. Binding agent is a solid form of the abrasive loose abrasive materials, with inorganic and organic types. Inorganic binder with ceramic, magnesite, sodium silicate and the like; organic a resin, rubber and shellac. One of the most commonly used is a ceramic, resin and rubber binding agent.
Holes in the ground when debris from the role of the chip and the chip, and can accommodate coolant, helps grinding heat dissipation. To meet the requirements of certain special processing, the pores can be impregnated with certain fillers such as sulfur and paraffin, so as to improve the abrasive performance. Such fillers, also known as the fourth element of the abrasive.
Means a common abrasive abrasive characteristics of the project are: shape, size abrasive, grain size, hardness, structure and bonding agent. Abrasive abrasive hardness refers to the external force from the abrasive surface of the shedding of degree of difficulty, it reflects the strength of binding agent holding abrasive.
The hardness of the abrasive agent is added depends on the amount of binding and the density of abrasive, abrasive grains easily fall off indication low hardness; vice versa, which means high hardness. Hardness level is generally divided into super-soft, soft, medium soft, medium, medium-hard, hard and superhard seven magnitude, from these levels can be subdivided in a number of small magnitude. Abrasive hardness measurement methods are more commonly used hand cone, mechanical cone method, Rockwell hardness measurement method and sandblasting assay.
The hardness of the abrasive and its dynamic modulus of elasticity has a corresponding relationship, which is conducive to the audio abrasive measured dynamic elastic modulus of said abrasive tools. In the grinding process, if they are grinding workpiece material hardness, generally used in low hardness abrasive; Conversely, the selection of high hardness abrasive.
Grinding of crude into tight, medium and loose categories. Each category can be further subdivided and number, with the numbers to differentiate between organizations. Abrasives organization number greater share of the abrasive grinding smaller volume percentage, the wider the gap between the grains, which means that more loose tissue. On the contrary, the smaller the number of organizations expressed more tightly organized. Loose organization is not easy to use abrasive passivation less heat during grinding, the workpiece can reduce heat deformation and burns. Tight organization abrasive grit easy to fall off, helps maintain the abrasive geometry. Abrasives organization only in the manufacture of abrasive formulations are controlled by, generally do not make determination.
Abrasive abrasive is dominated by diamond, cubic boron nitride and a binder to form a solid abrasive. Because diamond, cubic boron nitride high price, with good abrasion resistance, they are made with abrasive abrasive abrasive different from ordinary, except superhard abrasive layer, there are transition layer and the substrate.
Superabrasive layer is a cutting action from the part of the super abrasive grains and a binding agent. Substrate is in the grinding support care role played by the metal, bakelite or ceramic materials. Transition for connecting the substrate and superhard abrasive layer, the binding agent and, sometimes, may be omitted. A resin binder commonly used, metal, plated metal, and ceramics.
Bonded Abrasives manufacturing process are: assign material, mixing, forming, heat treatment, machining and inspection. With different binders, manufacturing processes are not the same. Mainly vitrified bond-pressure method, the abrasive and binding agent according to the weight ratio of formulation weighed, placed in the mixer are mixed evenly into a metal mold in the press forming of rough grinding. Blank firing kiln dried and then into the firing temperature is generally about 1300 ℃. When the binding agent is low melting point welded shut, the firing temperature is lower than 1000 ℃. Then the provisions of size and shape precision machining, final inspection products.
Resin bonded abrasives are generally at room temperature in the press forming, there is also the condition of heating under pressurized hot pressing process with heating. After forming in the hardening furnace hardening. Phenolic resin as binding agent, the curing temperature is 180 ~ 200 ℃.
Rubber bonded abrasives mainly used for mixing roller machine and rolled into thin slices, then die cutter punching molding; also some with loose material, the inner mold into the press molding. After the vulcanization molding vulcanization tank, a temperature of 165 ~ 180 ℃.
Metal bonded abrasives manufacturing process has two kinds of powder metallurgy and electroplating method, mainly for superabrasive abrasive. Bronze powder metallurgy method as the binding agent used after mixing at room temperature or under hot pressure molding, and sintering process. Plating with nickel or nickel-cobalt alloy as the metal plating, the plating process according to the abrasive bonded to a substrate, made of abrasive.
Special varieties with sintered corundum abrasive grinding and abrasive fibers and so on. Sintered corundum abrasive is alumina powder and the amount of chromium oxide mixing, forming, sintering at about 1800 ℃. This abrasive compact structure, high strength, mainly used for processing watches, instruments and other parts. Abrasive or fiber is adhered containing abrasive filaments (such as nylon) as raw material, and its good elasticity, mainly used for metal polishing materials and their products.
