BS ISO 230-4:1996 pdf free download.Test code for machine tools Part 4 : Circular tests for numerically controlled machine tools.
This part of ISO 23() specifies methods of testing and evaluating the circular hysteresis and the circular and radial deviation of circular paths that are produced by the simultaneous movements of two linear axes. Relevant measuring instruments are described in 6.63 of ISO 230-1:1996.
The objective of this part of Iso 230 is to provide a method for the measurement of the contouring performance of a numerically controlled machine tool.
2 Normative references
The following standard contains provisions which, through reference in this text, constitute provisions of this part of ISO 230. At the time of publication. the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of ISO 230 are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of fEC and ISO maintain registers of currently valid International Standards.
ISO 230-1:1996, Test code for machine tools — Part I: Geometric accuracy of machines operating under no-load or finishing conditions.
3 Definitions
For the purposes of this part of ISO 230 the following definitions apply:
3.1
nominal path
numerically controlled and programmed circular path defined by its diameter (or radius), the position of its centre and its orientation in the working zone of the machine tool and which may be either a full circle or a partial circle of at least 90°
3.2
actual path
path produced by the machine tool when programmed to move on the nominal path
3.3
circular hysteresis, H
maximum radial difference between two actual paths, where one path is carried out by a clockwise contouring motion and the other one by an anticlockwise contouring motion (see Figure 1)
NOTE 1 The reference for evaluation is the centre of the least squares circle of the two actual paths.
3.4
circular deviation. C
minimum radial separation of two concentric circles enveloping the actual path (minimum zone circles) as shown in Figure 2 and which may be evaluated as the maximum radial range around the least squares circle
NOTE 2 Circular deviation does not include set.up errors.
i.e. centring errors of the measuring instrument.
NOTE 3 Circular deviation measurement does not require test equipment with calibrated length whereas radial deviation (3.5) does need that facility. For differences between the circular
deviation g and the radial deviation (see annex A.
NOTE 4 A line situated in a plane is said to be circular when all its points are contained between two concentric circles whose
radial separation does not exceed a given value (see Figure 2 and also 6.61 of ISO 230.1:1996).
3.5
radial deviation, F
deviation between the actual path and the nominal path, where the centre of the nominal path is
obtained either,
a) from the centring of the measuring
instruments on the machine tool, or
b) from the least squares centring analysis for a full circle only.
NOTE 5 Positive deviations are measured away from the centre of the circle and negative ones towards the centre of the circle
(see Figure 3). The radial deviation is given by the maximum value, Fmsx, and the minimum value, Fm1,1.
NOTE 6 Set.up errors may be included in the radial deviation F: this is applicable only to a) above.
NOTE 7 For differences between the radial deviation Fand the circular deviation g see annex A.
3.6
identification of axes
designation of the axes which are moved to produce the actual path
3.7
sense of contouring
(clockwise or anticlockwise contouring, for circular deviation G and radial deviation F). Sense indicated by the sequence of the indices which identify the
axes moved when the movement is from the axis’
positive part indicated by the first index to the axis’ positive part indicated by the second index: e.g. the circular deviation C produced by the X and Y axes in a clockwise movement is denoted as Gy. in an
anticlockwise movement as Gxy
4.3 Machine warm-up
The tests shall be preceded by an appropriate warm-up procedure as specified by the manufacturer of the machine and/or agreed between the supplier/manufacturer and the user.
If no other conditions are specified. the preliminary movements shall be restricted to only those necessary to set up the measuring instrument.
4.4 Test parameters Parameters of the test are:
a) diameter (or radius) of the nominal path:
b) contouring feed;
c) contouring direction (clockwise or anticlockwise) as indicated according to 3.7:
d) machine axes moved to produce the actual path;
e) location of the measuring instrument in the machine tool working zone;
f) temperature (environment temperature, measuring instrument temperature, machine temperature) for radial deviation measurement only;
g) data acquisition method (data capture range if different from 360°, starting and stop points of the actual movement, number of measuring points taken for digital data acquisition, and whether a data smoothing process is applied or not);
h) any machine compensation routines used during the test cycle;
i) positions of slides or moving elements on the axes which are not being tested.
4.5 Test instrument calibration
For the checking of radial deviation the reference dimension of the test instrument shall be known.
5 Test procedure
To determine circular hysteresis, if. two actual paths have to be measured consecutively: one in a clock.wise contouring direction and the other in an anti-clockwise contouring direction.
All measured data corresponding to the actual path (including any peaks at reversal points) shall be used in the evaluation.
NOTE 8 For radial deviation. F, of a partial circle, set-up errors should be minimized.
6 Presentation of results
A graphical method of presenting results is preferred with the following test result data specified numerically:
a) circular hystere8is, H;
b) circular deviations C, for clockwise and anticlockwise contouring;
c) radial deviations, Fmax and Fmin, for clockwise and anticlockwise contouring, corrected to 20 °C.
Typical examples of presentation of test results are shown in Figure 4. Figure 5 and Figure 6.
The test report shall give the following:
— date of test;
— name of machine;
— measuring equipment:
— test parameters (see 4.4).
Magnification scale of the graphical presentation shall be stated.
7 Points to be agreed between supplier/manufacturer and user
The points to be agreed between the supplier/manufacturer and the user are as follows:
a) warm-up procedure prior to testing the machine (see 4.3):
b) test parameters (see 4.4);
c) which test result data for the circular hysteresis H, the circular deviation G and)or the radial deviation F [from 6a), 6b), 6c)] are required and shall be presented.