Aplaced test sphere, which has a diameter not less than 10 mm and not greaterthan 50 mm, is measured with 25 equally distributed points by a tip whoselength is stated by manufacturer. These 25 stochastic points should locate onarbitrary direction. Use all 25 measurements to compute the Least Squareassociated sphere. Calculate the distance between each of the 25 measurementsand the sphere center in the radial direction. The range of the 25 distances isMPEP. The actual measurement on site must be within the stated MPEP.
Choose7 different positions within the CMM measuring volume and measure a set of 5sizes gauge block at each position. Each size is measured 3 times, so can get atotal of 105 measurements in 35 groups. Calculate △ L-the error of this 105length measurements. All of them must be within the specified MPEE.
2.4.235 组测量长度中,允许最多有5 组,其三次重复测量中有一次超出规定的MPEE 值,对每个超差的测量长度,应在相应的方位再测10 次,如10 次复测得到的所有长度测量的误差值△ L 均在MPEE 值内,则示值误差(E)的检测被通过。
Inthe 35 groups of data, 5 groups of data at most can be permitted to have 1 ofthe 3 measurements over the stated MPEE value. If such case occurs, for eachoversized measurement, it should be measured again at the same position for 10more times. If all of the new 10 measurements‟ errors of △ L are within MPEEvalue, the verification for E is passed.
Thelength of probe tip above-mentioned is stated by manufacturer. The minimumlength of gauge block should be shorter than 30mm and the maximum length shouldbe longer than 66% of the maximum cater-corner length of CMM‟s working volume.The maximum length of block should be 1m if the value calculated is longer than1m.