壁厚千分尺主要用于测量管形工件的壁厚，其结构特点是固定测砧的测量面为球形或鼓形，其曲率半径一般为（5.00±0.35）mm。由于特定的结构特点和使用方法，壁厚千分尺活动测砧工作面经常会在某一位置上出现凹痕，造成平面度和示值超差，虽然示值超差并不仅仅是平面度超差引起 The wall thickness micrometer is mainly used to measure the wall thickness of tubular workpieces. Its structural feature is that the measuring surface of a fixed anvil is spherical or drum-shaped, and its radius of curvature is generally (5.00 ± 0.35) mm. Due to the specific structural features and methods of use, wall thickness micrometer foot anvil face often appear in a certain position on the dent, resulting in flatness and indication tolerance, although the indication tolerance is not just flatness tolerance cause