如图１所示的零件齿套，内孔需切梯形槽，槽宽６，其对称度相对B端面０．２。梯形槽６用成形车刀车成，测量a、b数值，其差值即为对称度。用测量范围０～１２５的游标卡尺测量（图２），卡爪宽度为６６mm，不能伸进花键孔内，无法测量。但用深浅尺或卡尺量高度部分测量，既不方 As shown in Figure 1 parts tooth cover, the hole required to cut trapezoidal groove width 6, its symmetry relative to the B end surface 0.2. Trapezoidal grooved car formed into a car, measured a, b values, the difference is the symmetry. Measured with a vernier caliper measuring 0 to 125 (Figure 2), the jaw width is 66 mm and can not extend into the spline bore and can not be measured. However, with the depth of the caliper or caliper height part of the measurement, neither square