在机械结构中,常有半圆孔或中开的带有压盖的孔。在压盖取下后,就难于精确测量孔径的实际尺寸。因半圆孔或中开孔,其中开面不会正好通过孔的直径。如 sh 型双吸中开水泵泵体上的轴承架和内部的密封环孔,就是一个典型实例。在中开面低于半径时,用一般通用量具测量,不但会产生误差,而且测量精度较低。现绍介一种量具及其测量方法,供参 In the mechanical structure, often with semi-circular hole or in the open with a gland hole. After the gland is removed, it is difficult to accurately measure the actual size of the aperture. Due to the semi-circular hole or hole, where the open surface does not just pass through the hole diameter. Such as sh-type double-suction pump in the pump body and the inner bearing ring bearing hole, is a typical example. When the surface is lower than the radius of the opening, the use of general-purpose measuring instrument will not only produce errors, but also lower measurement accuracy. Now introduce a measuring tool and measuring method for reference