FRIEDRICH VOLLMER FEINMESSGERÄTEBAU GMBH

The radiometric gauges from Vollmer operate contact-free and measure from a safe distance. They are characterised by their extremely narrow design: With some systems the C-frame is only 120 mm wide. The X-ray systems from Vollmer have digital detectors which give them extremely low noise values. Vollmer supplies the systems with high-quality ceramic tubes and the necessary cooler. The isotope systems also have digital detectors. A particular feature of the Vollmer systems is that the radiation source is located in a special tungsten drawer that can be easily removed from the gauge. Alloy compensation is made either in the classic manner using calibration plates or alternatively at the computer according to the customer's chemical alloy analysis or simply with a small contact thickness gauge that measures the absolute thickness at the start of the pass and transmits this value to the radiometric thickness gauge.

The gauges from the VSL Series measure the form, diameter, roundness and eccentricity of the rolls during the grinding process with very high precision. Form, radial run-out and eccentricity are measures with a precision of ± 1 µm. If an interface is available, they communicate online with the controller of the roll grinding machine and thus enable even more cost-effective use of the grinding machine. With the appropriate configuration, they measure the height and lateral alignment of the roll in the grinding machine before grinding, often enabling the set-up time to be significantly reduced. Vollmer produces the automatic roll measuring gauges for both bench-mounted machines where the roll is moved along the grinding wheel and for support machines where the grinding wheel is moved along the rotating roll. Vollmer supplies the systems for a broad spectrum of roll diameters.

VGraph is the software package for the recording and visualisation of data with extensive statistical data evaluation options. It synchronously records up to 16 measurement values – for example thickness, width and speed of the strip, rolling force or strip tension – on a production line, stores them and evaluates them statistically. With statistical functions such as histograms, Cp and CpK values and error lists, VGraph provides valuable decision aids for the evaluation and further use of the coil produced. The diagnostic instruments allow optimisation of the rolling process and the line engineering. The optional FFT analysis detects periodic fluctuations in the strip thickness. VGraph meets the needs of day-to-day strip production. One example: Random lengths of strip at the leading and trailing ends (drop-off) can be suppressed – even subsequently – in the statistical evaluations.

The BFI shapemeter rolls that we produce under licence from the VDEh-Betriebsforschungsinstitut (BFI) have a solid roll body with a homogeneous steel surface. They are normally installed instead of the existing deflector rolls. For the measurement of wedge-shaped strip, Vollmer offers a special solution that is also based on the BFI patent. It ensures that the flatness of the strips is measured correctly even though transversal stresses are created in the strip during coiling. Individual adaptation With individually manufactured diameters between 200 and 500 mm it is possible to precisely replace the deflector rolls in practically all mills. The outer surface of the roll body is absolutely homogeneous and can be reground on all standard roll grinding machines. The width of the measuring zones can be freely selected above 17 mm. The number of measuring zones that the roll should have is determined individually.

Over 130 successfully completed projects worldwide. With the combination of the understanding of the whole rolling process and the experience with modern control methods, we have implemented modernisation solutions in many rolling mills that have significantly improved the quality of the finished product and the efficiency of the production. For thickness control, for example, we convert mills from electric motor to servo-hydraulic screwdown of the stands. We also replace pancake cylinders or the combination of spindle and hydraulic screwdown with modern long-stroke cylinders. Vollmer has already modernised mills with a rolling force of 3,000 t. For the modernisation of the shape control system, too, Vollmer offers complete solutions through to the control and modification of the adjusting elements.

The systems of the VBP Series are offline tactile measuring systems which evaluate the cross-profile of the strip – irrespective of the alloy – on strip samples cut from the coil. They are frequently used in hot rolling mills for aluminium and steel, because it is here that the cross-profile is set for all the subsequent uses of the strip; the cross-profile measurement is of great significance at this point. During rolling, X-ray gauges are generally used which operate irrespective of the alloy and which have limited precision due to the high temperatures at the measuring point and due to the other ambient conditions. The high-precision cross-profile measurement is then performed offline using the VBP systems with their measurement accuracy of down to ± 1 µm. In this way the mill operators can achieve a high process reliability.

Precise even with low strip tension The segment rolls were developed specially for use in stretch bending levellers. The extremely free-running measuring rings permit high-precision shape measurement even with very low strip tensions. A rigid tubular section which forms the shaft of the roll supports several pivotably mounted measuring rings. They form the outer shell of the measuring roll over which the strip passes. Force sensors inside the measuring rings detect the force resulting from the strip tension. The sensors have high resolution, are overload-proof and maintenance-free. The data are transmitted through the centre axis of the roll and output as a Profibus signal.

The new standard for precision and speed With the new VTLG Series laser systems, Vollmer is giving strip thickness measurement new impetus: They combine the highest precision with rolling mill-oriented design. Thanks to their unique measuring method, they are suitable for use in cold rolling mills. With a measuring precision of ± 1 µm and scanning rate of up to 80 kHz, they offer the precision and speed necessary for the control of the strip thickness. VTLG systems are the only laser gauges to measure the strip thickness during rolling in the mill, thus opening up completely new possibilities in production and quality assurance for our customers. As with our contact gauges, they measure the thickness irrespective of the alloy – ideal preconditions for use in the rolling mill, but also on the annealing line, in the finishing section, on the strip edge miller or in the steel service centre.

The traversable straddle gauges are used for offline measurement. They are placed onto the roll and moved manually, thereby measuring the form of the rolls from crown edge to crown edge. They are characterised by a high measurement point density of 1 mm and a high repetition accuracy of ± 2 µm. With the evaluation software optimised over decades together with our customers for this application, curves can be pivoted and superimposed, centered and smoothed. The scope of supply also includes a panel PC.

Thickness measurement on plastic film samples requires automatic transport of the film strips through the measuring device, allowing for the flexibility of the material being measured. The desktop version of the VDM measuring station can be equipped not only with the pure measuring device, but also with PC-aided evaluation and graphic representation of the measurement results.