Renishaw expands on capabilities of XR20-W rotary axis calibrator software
2 mins read
Software for Renishaw's XR20-W now allows it to be used to measure the rotary positioning accuracy of an axis on many configurations of 5-axis machine tools where the XR20-W often cannot be mounted on the centre of rotation. With Renishaw's existing AxiSet Check-Up system for rotary axis and pivot points, users now have comprehensive tools to identify errors in their rotary axes.
The XR20-W rotary axis calibrator combines with Renishaw's XL-80 laser interferometer to allow rotary axis positioning performance to be measured with ±1º arc-sec accuracy. The method for off-axis measurement works by synchronising movement of rotary and linear axes so that the XL-80's laser beam is kept aligned throughout the test. Because the linear axis is moving, the measurements made by the XR20-W may include additional angular errors (eg pitch) from the linear axis. These contributory angular errors are then measured separately (using the XL-80 laser and angular optics) and removed from the initial rotary axis results. The end result is a set of data reflecting only the errors from the rotary axis itself.
The off-axis rotary software is provided as an extra cost option for XR20-W and includes a suite of software utilities, part program generators and an electronic format manual. The manual details all the requirements for the mounting set-up and associated custom hardware manufacture.
Understanding the location of the centres of rotations of the rotary axes relative to a machine's linear axes is key to precision machining, explains Renishaw. Without accurate data about these pivot points a machine's controller will be unable to reliably control the relative positions of the tool and the component as the rotary axes are moving, leading to inconsistent machining results.
Renishaw's AxiSet Check-up uses automated probing routines to gather performance data from a reference artefact, and includes simple yet powerful analysis. Alignment and positioning performance checks are carried out rapidly to benchmark and monitor complex machines over time. All tests exploit existing spindle-mounted Renishaw touch probes, with probing routines generated using machine-specific macro software supplied with Check-up. Renishaw recommends the use of its OMP400 or RMP600 touch probes with patented Rengage strain gauge.
To perform the test a user quickly locates a supplied calibration sphere within the machine tool's working envelope using a magnetic mount. Using the supplied custom macro software, a touch probe is then programmed to automatically take reference measurements around the sphere.
Measurement results from the test are output to a PC and presented in a Microsoft Excel spreadsheet, enabling easy to understand analysis of data in different formats. These include a graphical representation of performance that highlights tracking and centring errors, a function that compares two sets of data from the same machine, a simple 'pass' or 'fail' test against the user's pre-defined tolerances, and a history screen that allows comparisons of the performance of rotary axes over time.
To ensure the optimum analysis of rotary axis performance using Check-Up, it is important that machine's standard three linear axes are also performing within specification. This can be determined and corrected if necessary using Renishaw's XL-80 laser calibration system, and then regularly checked using a Renishaw QC20-W ballbar.
