“量具量仪产品质量分等标准总则(JB/GQF5050—86)”中,对于150×0.02mm的游标卡尺,要求其尺身刻线误差不超过(±0.012mm);对于大于150mm的游标卡尺,取其示值误差的60%为其刻度误差。但在加工过程中,尺身刻线误差往往不能控制。这主要表现为尺身刻线总长总是小于玻璃底板的刻线总长,其相差数值一般在0.025～0.01mm之间。这就会超出允许的刻线误差。为什么会出现这种尺身刻线长度小于玻璃底板刻线长度的现象呢?我们分析其主要原因,一是尺身(钢)的膨胀系数比玻璃底板大,因而在加工过程中的热胀冷缩现象比玻璃底板明显;二是感光胶层在 For the vernier calipers with a size of 150 × 0.02mm, the ruler scribing error shall not exceed (± 0.012mm). For vernier calipers larger than 150mm, take the standard vernier caliper Its indication error of 60% of its scale error. However, in the processing process, the ruler of the engraving error often can not be controlled. This is mainly manifested in the total length of ruler engraving always less than the total length of the engraved glass floor, the difference between the values ​​generally between 0.025 ~ 0.01mm. This will exceed the allowable scribing error. Why does this ruler engraved line length less than the length of the engraved glass floor phenomenon? We analyze the main reasons, one is the ruler (steel) expansion coefficient than the glass floor, so in the process of thermal expansion and cooling Contraction phenomenon than the glass floor significantly; Second, the photosensitive layer in