Whether with new systems or modernisation measures, the goal is always to achieve the optimum dimensional precision of the strips. That is why Vollmer, as the only manufacturer of measuring systems for the rolling of metal, adopts a holistic approach:
• From the grinding of the rolls
• through the sensors for measuring thickness and shape
• right up to the technological control system
• and hydraulic screwdown of the mills.
Vollmer don't just measure whether the strip is within the tolerance. With the mill control, Vollmer provides the user with the basis for being able to reliably meet the demanded specifications for the process.
Their experience, gathered over more than five decades also forms the basis for the software, for example for practice-oriented data visualisation and comprehensive statistical evaluations that are perfectly tailored to the needs of strip production, and in particular to those of cold rolling mills, and for the pass schedule memories that thanks to their ease of operation are quickly accepted by the users.
Roll measuring devices used either during grinding on the grinding machine or as traversable straddle gauges for offline measurement complete the Vollmer product spectrum for cold rolling.
Made in Germany
Vollmer develop all the systems at their company headquarters in Hagen at the heart of the German cold rolling industry. They are also represented worldwide by their branches and sales offices that are qualified to the highest standards.
The contact gauges that measure the thickness of the strip with an accuracy of a few micrometres are renowned for their outstanding precision and exceptional reliability: Almost 2000 systems that have gone into operation worldwide in recent decades are still in use even today.
They still form an integral part of the measurement technology in new plants where the highest precision is demanded.
Flexible from 0.01 to 24 mm
Tactile measurement is employed at all stages of the strip production process – on the annealing line and during rolling, on the finishing line or during strip processing as well as in the steel service centre. Vollmer delivers the systems in different versions for thicknesses from 0.01 to 24 mm.
Precise even on wavy strip
With a measuring precision of down to one micrometre per millimetre of strip thickness, they meet the demands of modern rolling mills. Contact gauges adapt to the strip passage and follow any waviness of the material. They thus compensate angular errors by actively adjusting the sensors perpendicularly to the wavy strip material.
The radiometric gauges from Vollmer operate contact-free and measure from a safe distance. They are characterised by their extremely lean 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.
The high-speed servo-hydraulic control of the mill screwdown closes the loop: The thickness values measured precise to the micrometre form the basis for quick and precise control.
Vollmer offers solutions for all control concepts from simple feedback control through to complete mass flow control, supplying the complete control system – from the sensors through the control technology right up to the hydraulics and the cylinder – from a single source.
Direct gap contol, predominantly for rolling of wedge-shaped strip and in tandem mills.
The heart of the system are two gap sensors which measure the gap width on the drive side and operator's side directly at the shaft of the work rolls, thus eliminating the attenuation of the measuring and adjustment signals caused by stand stretching, roll bearing clearance, etc. The thickness control system thus operates extremely quickly and directly.
Direct roll gap control effectively prevents wedge-shaped strip spreading to the side during rolling. In tandem mills it suppresses the lateral displacement of the strip caused by the high forces prevailing in the stand. The system is particularly effective during the rolling of thick strips: Strip leading and trailing ends are rolled out with high precision when using gap sensors.
Plate rolling mills achieve significantly improved results with direct gap measurement. Whether for strips or plates: The initial pass with gap sensors offers a significantly higher process reliability.
Efficiency through modernisatio
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.
Rolling mill with strip shape and strip thickness contol
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.