Abrasive tool

The abrasive tool, made of abrasive materials, is designed for mechanical processing of metal, leather, wood, glass, rock, plastics, etc. Industrial methods A. I. began manufacturing in the 2nd half of the 19th century. (at the time of the grinding machines). A. and. divided into 2 main types: hard (abrasive circles, heads, segments and bars, Fig. 1) and flexible (abrasive paper and goods made of it - tapes, disks, etc.). For the manufacture of A. I. apply electrocorundum (normal, white, alloy additives oxide of chromium, mono corund); silicon carbide (green and black); synthetic and natural diamonds. A. and. are available in ceramic, бакелитовой, vulcanol and less silicat, глифталевой and магнезиальной ligaments holding the individual abrasive grain. Abroad are also used any bundles.
Nomenclature of standard A. I. provides for about 750 sizes, and there are approximately 12 000 species of. Grinding wheels of electrocorundum and silicon carbide is produced with the diameter from 3 up to 1100 mm and a thickness of 0,5-200 mm and the diameter of grinding of holes from 1 up to 305 mm; from the diamond grains (in the bakelit, metal and ceramic bundles) with a diameter of from 6 up to 300 mm with thickness of a working ring of 1,5-5 mm and a width of 3 to 20 mm. An important indicator of A. and. - concentration of diamonds (the content of the diamond grain per 1 mm3 diamond layer; at 100% concentration in 1 mm3 contains 0,878 mg diamond ? grains). The concentration of diamonds in the circles in the diamond layer from 25 to 200%.
Abrasive paper and products made of it are produced on the basis of cloth and paper, with cutting grains of fused corundum, silicon carbide, glass and silicon. The rind is used for manual and mechanized grinding work, in particular - for belt grinding. Depending on the required strength of the skin is manufactured on the basis of calico, Serge, paper. The greatest resistance to break the skins on сарже.
From other types of cutting tools and A.. have a great number of randomly located grain - cutters with a pore between them, as well as the form and of the cutting edges. Chips removed them, as a rule, a small length. A. and. you can handle the details of materials of any hardness, work with cutting speeds exceeding that used in other processes of cutting, removed from the workpiece metal layer as thin, and of considerable size (the shares of micron and millimeters)IN the process of grinding abrasive grain as they blunting of art galleries, exposing the underlying them layer not dot grains. This property A. I. call the ability to self затачиванию. The more intense is chipping, chalking, the more self-sharpening A. and. In case of partial self-sharpening A. and. cutting the capacity of its restored not completely. For the full restoration of A. I. subjected to revision removing the surface layer of the grain. At the same time adjusted form инструмента.Правку A. and. carry out the diamonds in brooches, diamond pencils, diamond rollers and the various substitutes diamonds: carbide and steel rollers, smoll mop, grinding wheels of high hardness, abrasive bars, etc. Abrasive ability A. and. the higher, the more resistance it between revisions, and the period of service is greater than the lower layer of abrasive material is removed at each. Technology production A. I. to a large extent determines their working properties: the homogeneity of composition, hardness, wear resistance and dimensional accuracy, etc. To ensure the stability of the specified properties of the technological process are set by the type and the number of ligaments, the volume and number of wheel weight, pressure and method of pressing, the quantity of glue that you want to add in a bunch for the improvement of steels mass, temperature and time of thermal processing. Production of A. and. consists of the following basic operations: preparation of the ligaments, a mixture of abrasive masses, forming, heat treatment, mechanical finishing, testing the strength and hardness. Vitrified bond is made of finely chopped refractory clays of different compositions, marsh (hydroxide, potassium feldspar, etc.), perlite, quartz. Ligaments are mixed in a mixing machines (Fig. 2) with the abrasive grains and adhesive substance (envelope or liquid glass) and RUB through the vibration sieve or special car. Prepared thus the mass of the compact in hydraulic presses (Fig. 3). From drying chambers preparation coming in the tunnel обжигательные furnace, where they gradually warmed to the temperature of 1240-1320?C and then slowly cooled. A. I. on бакелитовой conjunction pass bacelit at t 180C. The temperature and time of thermal processing of A. I. determine their tensile strength, bending, compression and shock and respectively their operational properties. After firing A. I. undergo mechanical decoration - they give the required size and balance. A. I. experiencing the explosive strength of the load, excess working at 50%, and after determining the hardness of the mark. Manufacture of A. and. on vulcanol conjunction differs in that the blending of the mass perform on the mixing drums, and the desired thickness of the workpiece is achieved rolling on вальцах.Алмазные circles формуют at high pressures (up to 200 Mn/m2, or 2000 kgf/cm2). Thermal processing of diamond circles on metal binder lead at a temperature of 600-650?C, on the vitrified, with a temperature of 800-850 ?C. Tensile strength A. I. allows cutting speed 25-80 m/сек.Шлифовальная skin is made of the semi-automatic conveyor machines, where the process is carried out continuously. Application on a fabric or paper abrasive grain fixed on her мездровым glue or synthetic varnish. To increase the cutting properties of the skin of the grain are in electrostatic поле.А. im widespread in all sectors of the engineering industry, especially in the bearing. In the automotive, tractor and instrumental industry, up to 30-35% of the total fleet of machines are grinding, sharpening, lapping and polishing. The machines and A.. apply for Stripping works to remove the large allowances and when finish and precision machining for manufacturing of details of high accuracy and cleanliness of the поверхностей.Значительно developing the production of such promising species A. and., as circles in order to force grinding, Stripping rolled products, shaped grinding and other works related to the large grinding metal and the high accuracy of the обработки.: Ippolitov G.M., Abrasive tools and their operation, M., 1959; Kudasov G.F., Abrasive materials and tools. 2nd ed., L., 1967.Г.М. Ippolitov