物质质量的测定,多年来一直是用砝码在天平上进行比较,在计量学中称为衡量。衡量的精度与衡量器具的精确性直接相关,天平上的横梁是衡量时传递力或力矩的杠杆,杠杆上的支承将直接影响传递精度。用来制作天平横梁的支承,应具有在容许载荷下,工作接触面要稳定,材料的耐磨性能好,结构应能补偿在工作中的磨损,对温度变化不敏感,而且摩擦力矩极小等。因此,适合用作机械天平横梁的支承,都是采用刀子与刀承相配合的刀刃支承。刀刃支承是由两个平面所形成的棱形刃与刀承相接触所构成,精密天平是采用平面作为刀承,并经严格的精细研磨,这样构成 Determination of the quality of the material, over the years has been compared with the balance on the balance, called in metrology measurement. The accuracy of the measurement is directly related to the accuracy of the measuring instrument. The crossbar on the balance is the lever that transmits the force or the moment. The support on the lever will directly affect the transmission accuracy. Used to make the balance beam support should have under the allowable load, the working contact surface to be stable, wear resistance of materials, structure should be able to compensate for wear and tear in the work, not sensitive to temperature changes, and very small friction torque . Therefore, suitable for mechanical balance beam support, knife and knife are used in conjunction with the blade support. Blade edge is formed by the two planes formed by the edge of the knife blade contact with the composition, the precision balance is the use of flat as a knife bearing, and through the strict fine grinding, which constitutes