VM 182 Comparator System

The VM 182 comparator system serves for acceptance testing, inspection and calibration of machine tools and measuring equipment with traverse ranges up to 1520 mm. Machine tool builders and distributors can use the VM 182 to determine the linear and nonlinear error curves as well as the reversal error of machine axes according to ISO 230-2. In addition to determining the position error, it also measures guideway error orthogonal to the traverse direction of the machine axis The resulting error values can then be used in the subsequent electronics (display unit or control) for electronic error compensation. HEIDENHAIN TNC contouring controls can download the error compensation values directly.

Measuring assembly and signal evaluation
The VM 182 incorporates a steel scale with a two-coordinate phase grating of very high accuracy and a scanning head that moves over the grating without mechanical contact. During mounting, the scanning head is connected to the scale by an auxiliary carriage. The scale is clamped paraxially onto the machine table and the scanning head is connected to the machine quill with a coupling magnet. The relatively large tolerances of the VM 182 facilitate mounting and adjustment. After mounting is completed, the auxiliary carriage is removed from the scanning head. The incremental measuring signals with a signal period of 4 µm in both axes can be evaluated with the HEIDENHAIN ND 281B display unit and shown in measuring steps from 1 µm to 0.005 µm. The measured values can be sent through the ND 281B's RS 232 C data interface to a PC for further processing. Another possibility for signal evaluation is the HEIDENHAIN IK 220 counter card for PCs, which can produce a measuring step of approx. 1 nm. The ACCOM evaluation software for PCs evaluates the measured values in accordance with ISO 230-2, ISO 230-3 or the VDI/DGQ directive 3441.