At its Düsseldorf-Rath mill, Vallourec is using the new inline measuring system CaliView® developed by SMS group. After a successfully completed test in its sizing mill, tube and pipe manufacturer Vallourec has integrated the system into the line of the plug mill. There the system will regularly check the rolling mill and the passes. Such measurements will facilitate any corrections of the passes, guaranteeing that the tubes produced by Vallourec are of a constantly high quality. At the same time, the new digital system will make maintenance more efficient as the data it provides can be easily evaluated.
Vallourec is a market leader for premium tube and pipe solutions for the energy markets and industrial applications. The products and services are employed in challenging oil and gas drilling operations, in the latest power stations, in extravagant architectural projects and in high-performance machines and plants. At its Rath site in the north of Düsseldorf, Vallourec produces seamless tubes an two hot rolling mills. In order to be able to guarantee a consistently high quality for the demanding applications, the passes in the stands of cross-roll piercer, plug mill, reeler and sizing mill of the plug mill line have to be perfectly aligned at all times. Vallourec is now using CaliView®, for checking the pass settings in the sizing mill Figure 1. The inline measuring system developed by the plant engineering company SMS group, checks the contour and position of the passes both with the rolls installed in the mill and in the stand workshop. The mobile system consists of a light source, a camera and a computer with which the results of the measurement can be immediately evaluated. If pass settings have to be corrected, a further measurement directly after the correction indicates whether the correction has had the desired effect. The system thus helps to ensure quick and optimum alignment of both pass and mill with the pass line. Compared with conventional methods, this means reduced production losses and greater precision because it is no longer necessary to wait for the finished product before conclusions can be drawn as to changes in the passes.
In the sizing mill of the plug mill line in Rath, shells are rolled out to produce tubes and pipes of the desired sizes. A flexible process is employed here: A large number of stands with different passes for the various pipe diameters are kept in stock. A complete stand can be changed very quickly with minimum impact an the production. CaliView® now offers Vallourec the potential for optimising both, the adjustment of the rolls in the stands and the alignment of the roll stands and passes in the mill.
Vallourec is investing in CaliView® in order to allow maintenance of the plug mill line to be better planned and the costs to be reduced. "Regular overhauls and maintenance are key features of our corporate policy," says Dr. Ulrich Menne, Chairman of the Board of Vallourec Deutschland GmbH. "We are increasingly employing digital systems here to make our production more efficient. These allow us to accelerate our processes without sacrificing reliability."
Thanks to the regular measurements, Vallourec is in a position to document the condition of the mill very precisely. CaliView® saves the results so that a comprehensive history is created with which statistics an the causes of faults can be drawn up. A further benefit is that the measurement results can be realistically compared, as the same parameters are always used. The check of stands and passes before installation in the mill ensures that only stands found to be good are employed in production. Faulty stands can be dressed an the basis of the measurement protocol and the result can be quickly and easily checked using the measuring system. Regular measurements of the passes allow the condition of used stands to be documented so that the service life of the individual passes can be prolonged thanks to a more accurate determination of the maximum permitted wear.
In order to test the advantages of CaliView® in practice, Vallourec had first mandated the SMS group to check the alignment of the passes in the three-roll stands of the sizing mill using CaliView®. For this, Vallourec provided two newly dressed and one used stand with sizes between 231.4 and 231.5 mm that were to be measured at various positions in the mill.
SMS group equipped CaliView® with a suitable camera lens for the sizing mill and configured the system for the mill. For the measurement, the camera was installed at a distance of 22 m from the centre of the mill and the light source was mounted on the descaling unit on the mill inlet side using aluminium profiles, Figure 2
For determination of the mill centerline, the system is oriented to references that are surveyed with a fixed relationship to the mill centerline, Figure 3. The deviation is determined using a geodetic measuring instrument using reference points in the mill. At Vallourec, the references were mounted in two holders upline of the first and downline of the last stand, Figure 4. The deviations resulting from the fact that it is not possible to install the middle of the holders exactly on the mill centerline were entered during configuration of the measuring instrument. These were a misalignment of x = -7.2 mm; y = +2.2 mm on the inlet side and of x = -1.1 mm; y = +3.2 mm on the run-out side. The system takes these deviations from the pass line into consideration during the measurement.
After the preparatory work, the three stands were installed in various positions in the mill and measured a total of seven times, Figure 5 . The first four measurements served to check the mill. For this, the three different stands were checked in various positions in order to detect any deviations. The results were comparable with the different stands in all the stand positions. Measurements 5-1 to 5-3 were carried out to confirm the measurement accuracy by measuring a stand in various positions in one stand location. During measurement 5-1, stand 27 was positioned normally, during measurement 5-2 with a lateral misalignment of 3 mm and during measurement 5-3 with a vertical misalignment of mm. Both misalignments were exactly detected by the measuring system. As a result, the system identified a general vertical misalignment of the mill frame: The pass line of the sizing mill deviates by +5 mm from the optimum pass line
The Vallourec representatives were impressed by the simple and quick measurement of mill and stands using CaliView®. The data supplied by the digital system help to make processes more efficient and can be easily exported for further use. After the first test measurement in the sizing mill of the plug mill line, Vallourec decided to buy the system. In addition to the regular measurements of the mill frame, the stands are now also checked in the workshop after maintenance and repairs in Rath. This allows service intervals to be redefined and tool lives to be extended. The relationship between pass and product allows technological conclusions to be drawn - a great advantage for flexible production in Düsseldorf-Rath. And not only there: Representatives of other Vallourec sites have already indicated an interest in CaliView®, too.