Accuracy Judgment Standard of Coordinate Measuring Machine

Accuracy Judgment Standard of Coordinate Measuring Machine

　　 In recent years, the technology of coordinate measuring machine has developed rapidly. As the product functions become more powerful, some unsatisfactory measuring products will inevitably appear. For a high-precision measuring instrument such as a coordinate measuring machine, accuracy is the basic factor for judging its quality. So, how do we assess whether a coordinate measuring machine is qualified? The following is the accuracy assessment standard of a coordinate measuring machine for your reference.

The accuracy assessment standard of 　　 coordinate measuring machine: ISO 10360

　　 In 1994, the ISO 10360 international standard 'Acceptance, Inspection and Re-inspection of Coordinate Measuring Machines' was implemented. This standard explains the basic steps for the performance testing of a three-coordinate measuring machine. China's current national standard for measuring machines GB/T16857.2-1997 'Coordinate Metrology-Part 2: Performance Measurement of Coordinate Measuring Machines' is equivalent to the corresponding ISO standards.

　　ISO 10360 is divided into the following six under the main heading 'Geometric Product Specification (GPS)-Coordinate Measuring Machine (CMM) Acceptance Test and Re-inspection Test' Part:

　　—Part 1: Vocabulary;

　　—Part 2: Coordinate measuring machine for measuring linear dimensions;

　　—Part 3: Configure turntable Coordinate measuring machine whose axis is the fourth axis;

　　—Part 4: Scanning measurement type coordinate measuring machine;

　　—Part 5: Coordinate measuring machine of multi-probe detection system ;

　　—Part 6: Calculate the error evaluation of Gaussian auxiliary elements.

　　The ISO standard mainly includes three main parameters: length measurement allowable indication error (MPEE), allowable detection error (MPEP); for scanning measurement, allowable scanning detection error (MPETHP) is used. Before purchasing a measuring machine, the user needs to be familiar with the acceptance criteria of the measuring machine. The following is a brief introduction about ISO 10360:

　　ISO 10360-1 (2000) 'Vocabulary'

　　 The first part of the standard defines all the vocabulary definitions related to coordinate measuring machines. For example: 'detection system' or 'standard ball

　　ISO 10360-2 (2001) 'Coordinate Measuring Machine for Measuring Linear Dimensions' (MPEE) and Maximum Allowable Detection Error (MPEP).

　　The allowable indication error of length measurement MPEE:

　　 In any 7 different orientations of the measurement space, measure a group of 5 sizes of gauge blocks, and measure the length of each gauge block separately All three measurements must be within the specified MPEE value range.

　　 Allowable detection error (MPEP):

　　 25 points are measured with precision standard balls, and the detection points are evenly distributed. The allowable detection error MPEP value is the value of all measured radii.

　　ISO 10360-3 (2000) 'Coordinate measuring machine with turntable axis as the fourth axis'

　　 For a measuring machine equipped with a turntable, the measurement error of the measuring machine is This part is defined. It mainly includes three indicators: radial four-axis error (FR), tangential four-axis error (FT), and axial four-axis error (FA).

　　ISO 10360-4 (2003) 'Scanning measurement type coordinate measuring machine'

　　This part is applicable to coordinate measuring machines with continuous scanning function. It describes the measurement error in scanning mode.

　　Most measuring machine manufacturers define 'spatial scanning detection error under THP'. In addition to THP, the standard also defines the scanning detection error in the case of THN, TLP and TLN.

　　 Allowable scanning detection error (MPETHP): Scan along 4 determined paths on the standard ball. The allowable scanning detection error MPETHP value is the difference of all scanning radii.

　　 Note: The description of THP includes the total measurement time, for example: THP u003d 1.5um (scanning time is 72 seconds) THP describes the scanning characteristics of the density point along the known path. ISO 10360-4 further explains: TLP: Scan along a known path with low-density points. THN: Scan along an unknown path with high-density points. TLN: Scan with low density points along an unknown path.