梯形螺紋在機械上用得很廣,如車床的走刀絲桿,鏜床的升降絲桿,以及其他機床上的傳動絲桿,差不多都是梯形螺紋的,因此梯形螺紋的測量,是我们必須熟悉的。梯形螺紋的斷面形狀如圖1,它的螺紋頂和底都是平的。在蘇聯,螺紋角規定為30°,歐美國家一般規定為29°。梯形螺紋的测量,主要也是测 Trapezoidal thread used in a wide range of machinery, such as lathe guide screw, lifting screw boring machine, as well as other machine drive screw, almost all trapezoidal thread, so the trapezoidal thread measurement, we must be familiar with of. Trapezoidal thread cross-sectional shape shown in Figure 1, the thread top and bottom are flat. In the Soviet Union, the thread angle is set at 30 °, and the general provisions in Europe and the United States are 29 °. Trapezoidal thread measurement, mainly measured