The punching hole measurement is based on the measurement method of the pass-through gauge. The value is small, so when you use caliper measurement to record, you can generally record the small value (exclude the small value, for example, the error caused by the measurement error), (not excluded There are special cases) There is no practical significance to record the large value and the average value. The difference in the size of the aperture measurement in all directions should be recorded in the roundness of the geometric tolerance, not the aperture.
In addition, if it is surveying and mapping, and there is no size to refer to, you should determine it according to its cross-section. You cannot just take the average value. For example, the small value you measure may be caused by the wear of the punch somewhere. The light band of the cross section is extremely small, so this minimum value is meaningless.
In general, the wear of the punch is caused by the smaller punching (special holes need to be analyzed specifically), so you can take the maximum value during surveying and mapping. Do not forget the quality of the cross section, because the basic size of the hole diameter is taken when the punch is manufactured + The maximum value within the allowable deviation is multiplied by 0.5 to 0.75 to leave the amount of wear. After a period of use, the punching becomes smaller, but as long as the cross-sectional quality is passable, then the value is still within the tolerance range. The value is correct.
