图 1是内燃机油嘴油泵滚轮体部件的一种滚轮销 ,滚轮销的端部为球冠。球冠在科研试验中也有应用 ,例如 ,摩擦学试验研究中也常常需要采用端部为球冠的销试样 (球面销 )。总之 ,具有球冠的零件并不少见。由于球冠小于半球 ,其表面上任一圆弧所对应的圆心角小于 1 80°,用常规量 Figure 1 is a kind of roller pin of internal combustion engine oil pump roller body part, the end of roller pin is a spherical cap. Ball caps have also been used in scientific research. For example, it is often necessary to use a pin specimen (spherical pin) with a spherical tip in the tribological test. In short, parts with a spherical cap are not uncommon. As the ball is less than the hemisphere, the surface of any circular arc corresponding to the central angle is less than 180 °, with the conventional amount