WinWerth® measurement software

In practice, a few sizes of production parts often have to be determined "quickly". This task is also carried out by employees who do not permanently deal with the operation of coordinate measuring machines. To enable effective work in this environment, the operation is limited to the most necessary. The "intelligence" of the WinWerth® measurement software then takes over, for example, the exact determination of the object area to be captured, the selection of the geometrical element to be measured (e.g. e.g. straight line, circle, corner point) as well as the linking algorithms for determining geometrical characteristics such as distances, angles and diameters.

For more complicated measurement tasks, the operator can take over parts of the automatic processes (setting windows, selecting features) themselves and familiarise themselves step by step with the more detailed control of the measurement sequences. For support, measurement points or scan lines are automatically distributed on the geometry elements to be measured, e.g. as circles, cylinder surface lines, stars or spirals, taking into account the necessary traverse paths. The complete measurement sequence, including evaluation, is first created offline using the CAD model or online with the minimum number of points for the respective geometry element. Measurement points and scan lines can be subsequently moved, deleted or added with the mouse or via a dialogue. Measurement sequences specified in this way can be saved and called up as an automatic sequence in the event of repetition.

TomoSim is the first coordinate measuring software to simulate the tomography process offline using CAD data or a point cloud in STL format. The realistic simulation, taking into account the set CT parameters, enables the calculation of a volume including all significant artefacts. For example, an initial sample inspection programme can be taught in at an offline workstation in parallel with the production of the first workpiece and the performance of other measurements on the machine using the WinWerth® measurement software. This enables TomoSim to speed up processes and reduce downtimes, e.g. for TomoScope® machines in multi-shift operation.

In addition to a completed program creation and feasibility check in time for the completion of the first workpiece, the simulation of the tomography process allows CT parameters to be tested and optimised. With the help of the simulated volume, significant artefacts, e.g. due to beam hardening or too few rotary increments, can be detected and, if necessary, an appropriate artefact correction can be selected. Another new feature is the complete offline programming of volume-based analyses such as burr detection, void analysis, porosity analysis, text recognition, SurfaceScan Predefined or in volume sections.

Another benefit of the CAD module integrated in WinWerth® is that the CAD information can be used to position the coordinate measuring machine. Werth was probably the first manufacturer of coordinate measuring machines to introduce this technology back in the mid-1990s under the name CAD-Online®. The entire measurement sequence can be controlled by selecting the geometric features on the CAD model. The measuring machine automatically moves to the generated measuring positions and measures with the selected sensors.
In this way, for example B. automatically capture measurement points as point clouds or measure larger areas with the Werth 3D Patch or confocal sensors by automatically aligning the individual measurements in high resolution. Technology parameters such as the illumination setting for the image processing sensor can be set directly on the measuring machine, taking into account the interaction between the illumination, measuring object and imaging system. Collisions are avoided by automatically modifying the movement sequences based on the workpiece and machine or sensor geometry.

Many CAD systems now offer the option of integrating PMI (Product and Manufacturing Information) data. In addition to the geometry description of the CAD features, the resulting CAD data sets also contain the dimensions defined by the designer. When the geometrical characteristics are selected, the WinWerth® measurement software distributes measurement points or scan lines on all geometrical elements that are to be linked to find a solution, and the measurement sequence is created at least partially automatically. Unfortunately, this solution is still not widely used due to the increased requirements when creating the CAD model.

If the complete measurement sequence is to be generated fully automatically, all the necessary parameters must be stored in the PMI data or determined automatically by the measurement software. If these requirements are met, the complete measurement sequences for the measurement of close-tolerance metal tools for the production of injection moulds for contact lenses, for example, can be created fully automatically in WinWerth®. The measurement is carried out with a multisensor coordinate measuring machine using a combination of optical distance sensors with image processing and with the aid of an automatic rotary/tilt axis for the workpiece.

Contours larger than the field of view of the respective lenses can be captured as a whole using automatic contour tracking in conjunction with the CNC axes of the coordinate measuring machine (contour scanning). This scanning method is well suited to checking a few relatively large contours, e.g. on punching tools. 
Another method for capturing larger areas of the workpiece is "raster scanning HD" (patent). Here, the image processing sensor captures images of the workpiece at high frequency during movement. These are resampled and superimposed to create an overall image with a resolution of up to 20,000 megapixels. In this way, for example, 100,000 small bores on large fibre couplers are measured in just 35 minutesb instead of 7 hours. Accuracy is also increased by measuring even large areas at high magnification and averaging over several images, which improves the signal-to-noise ratio. The process can be customised to the requirements of the measurement task.
With Raster Scanning HD P, image acquisition only on areas of interest using a preset path results in a further reduction in measurement time and data volume compared to rectangular raster scanning of the entire workpiece with Raster Scanning HD N. On rotary axis devices, Raster Scanning HD ROTARY enables image acquisition during rotation with measurements on the "unrolled" overall image of the lateral surface of rotationally symmetrical workpieces.

With 2D contour image processing and the associated image processing filters, measurements can also be taken in any cross sections of the CT volume or point cloud. This makes it particularly easy to measure workpieces made of several materials, among other things. In addition to planar cross sections, cylindrical CT volume sections are also possible for reliable measurements with the Volume Section Sensor or inspection with WinWerth® VolumeCheck. The base area of the cylinder is not limited to circles and can take on any mould. As a result, both a 3D view of the cut surface and the unrolled 2D lateral surface of the cut cylinder are displayed.

Eccentric Tomography allows the workpiece to be positioned anywhere on the rotary table (patented). There is no need for complex and time-consuming alignment of the workpiece, which increases ease of use. Sectional tomography or ROI tomography (ROI: Region of Interest) is used to measure parts of the measuring object with high resolution without having to capture the entire measuring object, e.g. e.g. with Raster Tomography, which is time-consuming and memory-intensive. Multi-ROI tomography offers a combination of the benefits of eccentric and sectional tomography. Several high-resolution parts can also be selected at any position in the measuring object.

In the X-ray tomographic measurement of metal-plastic components such as feeding connectors, the metal pins often cause artefacts due to beam hardening and scattered radiation, which make measurements on the plastic housing more difficult. In Dual-Spectra Tomography, the measurement software combines two CT measurements at different cathode voltages into one volume. The radiation spectra are matched to the two materials. The corresponding reduction of artefacts in the volume reduces the measurement uncertainty when determining the sizes of the different materials. To this end, the WinWerth® MultiMaterialScan uses the patented subvoxelling process to automatically calculate separate STL point clouds for each material from the CT volume data, even for several different metal components.

For users untrained in operating measuring devices, WinWerth® offers the option of simply selecting the part number and using it to start an automatic programme sequence. Alternatively, this can be done by scanning a barcode on the production order. Automatic fault handling helps, for example, if parts are not inserted correctly.

Alternatively, a workpiece changing system can be integrated into the housing of the TomoScope® coordinate measuring machines without any further precautions for radiation protection. With several ready-fed pallets, measurements can be carried out overnight and at weekends.

Automatic feeding by feeding devices can also be integrated. For this purpose, the measuring programmes can be prepared remotely at offline workstations. The workpieces are fed into the safety area of the robot via an airlock. The geometrical characteristics of workpieces such as valve blocks, housings and castings are determined almost every half minute, a nominal-to-actual comparison is carried out with the measuring point cloud of a master part and the workpieces are tested for defects such as burrs. The measurement results can be determined with the help of parallel evaluation computers and merged in a common protocol, including the measurement results of interlinked multi-sensor devices.

To illustrate the deviation of the workpiece geometry from the target values, a comparison to the CAD data with a colour-coded display of the deviations in WinWerth® is suitable. This procedure is essential for checking free-form surfaces. For measurement, the areas of interest of the object are scanned or captured as a point cloud. WinWerth® then compares the measured values with the CAD model. The result is documented by vectorial or colour-coded display of the deviations to the CAD model. This evaluation can be carried out as part of the measurement sequence on the machine or in offline mode at a separate evaluation station. The colours of the measurement points illustrate the deviation between the target and actual values. In order to include the part tolerances in the visualisation, they are divided into four basic classes:

• positive within tolerance
• negative within tolerance
• positive outside tolerance
• negative outside tolerance

The amount of deviation is displayed using colour coding. Alternatively, the user can configure colour coding according to their requirements.

In order to incorporate the measured or calculated deviations into the manufacturing process, the specification data can be modified largely automatically with WinWerth® FormCorrect. For this purpose, the deviations between the original CAD model and the measured data of a sample workpiece are determined and mirrored on the model. From this, the measurement software generates a corrected CAD model that can be used to compensate for systematic manufacturing deviations in the plastic injection moulding process and 3D printing. In contrast to conventional reverse engineering, the application is considerably simplified. Due to the high precision, only one correction loop is often required, meaning that the costs of the development process can be significantly reduced. For high-resolution corrections and for the modification of internal surfaces, the use of coordinate measuring machines with X-ray computed tomography is recommended. A similar procedure is possible with the 2D BestFit software. Mould correction can be used both for running in new cutting tools (profile grinding, form milling) and for correcting positioning deviations during wire EDM.

If no CAD data is available, the measurement points can be selected interactively by the operator. In WinWerth®, both direct selection with the mouse and automatic decomposition into standard geometry elements are possible. Starting from a starting point, further points are automatically added until the form error of the selected feature (e.g. e.g. cylinder) increases noticeably. This signals that the limits of the feature have been reached and the process is completed.

It is more effective to define the measurement sequences using 3D CAD data. Simply selecting CAD features automatically selects the necessary measurement points (patent). Based on the selection of CAD patches, all measurement points of the measured object that can be geometrically assigned to this patch are selected, taking into account the specified edge distances. This results in a complete capture of the mould of the corresponding feature with the maximum number of points.

In practice, it is common to define drawing dimensions in 2D views and cross sections. This must also be taken into account when analysing tomographically generated measured data. For this purpose, planes can be defined in the workpiece coordinate system and intersected with both the CAD target data and the actual point cloud. WinWerth® automatically extracts contours that represent the target data and the actual contours. The same software functions are used to evaluate the 2D sizes in cutting contours created in this way as are available for evaluating contours scanned using image processing or a stylus.