Carbon graphite electrical products
Carbon graphite electrical products
Carbon graphite products have good electrical conductivity and thermal conductivity properties, and has a role in the arc under the non-fluxed, good self-lubricating properties, high temperature and thermal expansion coefficient ranging from the characteristics of certain electrical products that are valuable. Therefore, at present, has been widely used in the manufacture of certain carbon-graphite material under special conditions at the conductive material.
Brush for motor commutator or collector ring on, as the export or import current sliding contact body. With the development of science and technology, the electrical type and use of the working conditions more and more diversified, and therefore have required a variety of different goods pole brush to meet these requirements, it is also the type of brush with the motor industry and many more and more. Such as metal graphite brush is a metal powder and graphite powder as raw materials by mixing, suppressed by sintering. General Department of brush billet molding, molding at the time, graphite powder due to the role of stress from layered arrangement, resulting in a clear anisotropy. Natural graphite as the matrix of the brush is particularly evident, the direction perpendicular to the surface stress is greater than the resistivity parallel to the direction of the pressure surface resistivity. Example, D104 brush resistance rate was 5.7. Other factors, such as thermal expansion coefficient, hardness and strength of performance, is also anisotropic. With the matrix graphite content increases, the degree of its anisotropy, the more obvious. Billets for the effective use of the characteristics of anisotropy, and better meet the needs of motor running in electricity will be cut into billets brush body, attention should be given the pressure of rough surface and non-stress direction noodle. General hope that cross-cover-for-brush to the film direction (along the direction of rotation commutator) the resistance to large, so that there is beneficial to limit the change to short-circuit current between the films in order to improve the performance for the brush. Therefore, when the rough cutting brush, according to the effective principles. Whether it is for the commutator or collector ring for the brush, its high degree of r can not be taken from the rough thickness of c, use the brush on the commutator, and its thickness t must be used for rough machining the thickness of c for use in collecting ring on the brush, and its t with a interchangeable.
In order to meet the needs of the different characteristics of motor, motor used on several different forms of brush grip. Brush has been the main grip, monoclinic oblique brush grip and dual grip brush. Straight grip brush is usually used for medium-sized or one-way reversible rotary motor, and sometimes also used for large-scale low-speed motor. Monoclinic grip brushes are generally used for one-way rotation of the DC motor. Double-oblique grip brush is generally used for large motors and the motor to the difficult, according to its tilt angle difference can be used for reversible or one-way rotating motor. In order to adapt to grip with the brush, the brush manufacturers produced as many as seven, the appearance of 80 kinds of different shapes of the brush. Divided into major categories according to 1) radial-style brush, also known as hub-and-brush, flat-topped radiation-type brush with radial-type brush grip used for a one-way operation of the motor, but the request must brush grip accurate processing, brush body itself should not be too long, the co-ordination of grip and brush clearance must also be modest. This can avoid work because of brush friction will grip brush to brush the wall, so that brush Casey phenomenon generated; but will also prevent operation at the direction of transformation process, caused by crossing brush with the commutator Noodles contacts reduced, resulting in increased current density and hence resulted in overheating, fire phenomenon. Radial brush applied to a one-way operation of the motor, because the anterior wall of brush and brush close to the grip, we can make sure commutator brush at the surface of stable operation. 2) forward and backward-style-type brush: Brush placed in such a grip brush, the brush of the commutator must tilt angle. At the topping-out of the brush can also brush the top of the form of tilt. 3) extend riveting; 4) molding method; 5) The welding method: brush body in accordance with the regulations on the location of a good weld drill hole, and at its upper or welding copper hole will be penetrated through brush body welding wire hole with solder welding in prison.
Wear-resistant carbon and graphite products often substantial as structural materials for use in machine-building industry and chemical production, has become a carbon and graphite products an important branch of industry, whether at home or abroad, wear-resistant carbon and graphite products, variety and quantity are rapid development.
With a lot of metal or non-metallic materials compared to carbon and graphite materials, high thermal stability with high thermal conductivity, thermal expansion coefficient than the lower, especially carbon and graphite materials for the majority of acid-base and salt solution are can not afford to chemical reaction. Graphite materials have self-lubricating properties, in the absence of lubricants under conditions of friction with many metal parts, the parts of the friction coefficient of graphite is only 0.04-0.05, that is, its low friction coefficient.
Because the majority of lubricants at high temperatures will break down or even fire, so much at high speed, high pressure and high temperature operation of the equipment can not use ordinary lubricants to improve the wear resistance of moving parts. Therefore, at present, in some machinery and equipment used by the carbon and graphite material processing of bearings, pistons, piston rings and seals and so on. Those from carbon and graphite material parts can be at -200 degrees Celsius to +200 degrees Celsius temperature range of corrosive media and sport at high speeds (such as 100 meters / second) without lubricants and operate normally. Of course, the carbon and graphite materials have their own shortcomings, such as friable and non-impact resistance, and thus its practical use is also subject to certain restrictions.