螺纹中径的测量,常用螺纹千分尺,或用三针测量法。在多品种公制螺纹加工中,用投影仪和工具显微镜测量螺纹中径,方便可靠。如图所示,将工件装在仪器工作台上,且使螺纹轴线与仪器米字线的横线平行,这时可移动工作台,使被测工件螺纹投影一侧的牙槽形(凹)与米字线素线对准,直到米字线与牙槽形重合。确定工作台坐标读数。再按工件径向进给移动工作台,使工件螺纹投影另一侧的牙尖形(凸)与原米字线重合。计算工作台移动的距离,就是被测 Thread diameter measurement, commonly used thread micrometer, or with three-pin measurement. In the multi-species metric thread processing, with a projector and tool microscope measuring thread diameter, convenient and reliable. As shown in the figure, the workpiece is mounted on the instrument table, and the thread axis is parallel to the horizontal line of the instrument meter word line. In this case, the worktable can be moved to make the alveolar shape (concave) Align with the rice word line until the rice word line coincides with the alveolar shape. Determine the table coordinate readings. Then move the work table radially according to the work piece, so that the other side of the thread projection project cusp (convex) coincides with the original meter word line. Calculate the distance the table moves, is measured