ISO 10360-3:2000 pdf download
ISO 10360-3:2000 pdf download.Geometrical Product Specifications(GPS)- Acceptance and reverificationtests for coordinate measuring machines(CMM)— Part 3: CMMs with the axis of a rotary table as thefourth axis.
5 Acceptance test and reverification test
5.1 Principles
The principle of the assessment method is to establish whether the CMM is capable of measuring within the stated maximum permissible errors (MPEFR, MPEFT, MPEFA) by determining the variation of the measured coordinates of the centres of two test spheres mounted on the rotary table.
It is noted that on a perfect four-axis CMM, the location of the measured centres of the test spheres would remain fixed in the workpiece coordinate system while the table is rotated.
Each test sphere centre is determined in three directions: radial, tangential and axial. The position of each test sphere centre is represented in the workpiece coordinate system on a rotary table.
The centre of each test sphere, mounted on a rotary table, is measured in a series of measurements with different angular positions of the rotary table.
The errors of indication (FR, FT, FA) are calculated separately for each test sphere as the range between the maximum and minimum measurement results for each of the three directions.
In the following:
acceptance tests are executed according to the manufacturer’s specifications and procedures; reverification tests are executed according to the user’s specifications and the manufacturer’s procedures.
5.2 Measuring equipment
5.2.1 Two test spheres (A and B), with diameters no less than 10 mm and no greater than 30 mm and with certified form.
The diameters of the two test spheres, used in these tests as the corresponding input quantities, need not be calibrated since only the centres of the test spheres are used to determine the three four-axis errors. The form of the test spheres must be calibrated since the form deviations influence the test results and shall be taken into account when proving conformance or non-conformance with specifications.
The mounting of the test spheres should be sufficiently rigid to avoid errors due to bending especially when the axis of the rotary table is horizontal.
5.3 Procedure
Position the test sphere A on the rotary table as close as possible to the rotary table surface at a radius r, in accordance with Table 1. Position the test sphere B approximately at the same radius, r, and approximately diametrically opposite the test sphere A at a height, 1iVi (see Table 1 and Figure 1).
Define a Cartesian workpiece coordinate system on the rotary table (see Figure 1) conforming to the following conditions:
a) the centre of test sphere B (farthest from the table surface) establishes the origin;
b) the primary axis which defines the axial direction shall be parallel to the axis of the rotary table;
C) the secondary axis which defines the radial direction shall lie in a plane that contains the primary axis and the centre of test sphere A.
NOTE 1 The tertiary axis defines the tangential direction.
Once the workpiece coordinate system is established begin the test by measuring test sphere B in its original position (position 0). The user can choose any angular position other than the zero reading of the rotary table for position 0 in Table 2.
Then the rotary table is rotated through a series of seven angular positions, and the position of the test sphere A is measured in each position. It is recommended that the positions of the seven measurements extend at least 7200 from the starting position. Then the rotary table is rotated in the opposite direction to seven angular positions and the test sphere A is measured in each position. When the rotary table is returned to its starting position both test spheres should then be measured as position 14.
The rotary table is then rotated in the same direction to seven different angular positions and then rotated in the opposite direction to seven angular positions. The test sphere B is measured at each position. When the rotary table is returned to its original position both test spheres should be measured as position 28 (see Table 2).
NOTE 2 The heights and radii according to Table 1 are specified to facilitate comparisons between CMMs.
NOTE 3 The values of 200 mm transform each second of arc of angular error to approximately one micrometre of linear error. For aid in comparison of machines with differing measuring volumes, and in matching machine capability to workpiece tolerance requirements for large parts (i.e. parts larger than the table size), the errors resulting from the test procedures above are approximately proportional to the height and distance used.
NOTE 4 The user may choose any loading, location and orientation of the rotary table on the CMM within the limits specified by the manufacturer. The manufacturer and user may agree to additional test(s) using different test sphere location(s), if required.
NOTE 5 Some CMMs use the rotary table as a means of extending the measuring volume. On such CMMs, the test sphere may only be accessible to the probing system over an arc of rotation of the table which is less than 360°. On such machines the starting angular position of the rotary table must be such that the positions of both test spheres can be measured.
