MEASURING SYSTEMS IN
MEASURING SYSTEMS IN TUBE MILLS MEASURING SYSTEMS IN TUBE MILLS High-resolution Diameter Profile Measurement Diameter profile measuring system in a PQF ® Mill New rolling technologies in the production of seamless steel tubes such as individually adjustable rollers in three-roll stands in PQF ® or FQM Mills or adjustable end stands in stretch reducing mills have made suitable and cost-efficient measuring systems necessary to meet the stricter demands for transparency in the rolling process and maximum accuracy in measurement. This demand can be met optimally using highprecision laser triangulation sensors. For this preferably 18 or 24 sensors are arranged circularly around the circumference of the tube. Through synchronization of the individual sensors among each other, the measured data of all sensors are outputted simultaneously at measuring rates in millisecond range, resulting in a distortion-free representation of the outside profile of the tube. This configuration is particularly interesting in combination with a Multi-Channel wall thickness measuring system because it represents a fully integrated solution for measurement of all geometric parameters on hot tube requiring only one complete gauge. A version as independent gauge without wall thickness measuring system is also available. IMS has been using laser triangulation sensors from the Swedish company LIMAB, based in Gothenburg, since 2007 to determine tube position as an alternative to CCD camera systems. The business relationship between LIMAB and IMS was up-graded to a partnership in the field of diameter measurement in 2009 with integration of high-resolution diameter measurement by means of LIMAB measuring heads into the IMS Multi-Channel tube wall measuring system. SYSTEM FEATURES Equipped with 18 or 24 sensors, other versions on request Data transmission via Ether-Net at up to 1000 kbit/s Installation on water-cooled protective ring and behind protective doors with heat protection shields for measurement in hot environments Protection against contamination by pressure blower Easy-to-use calibration equipment Measuring principle and configuration The measuring principle used by the individual measuring heads is based on a distance measurement by means of optical triangulation. Triangulation measuring principle A laser point is dropped on to the surface of the material to which the distance is to be measured. The laser point is reflected diffusely by the surface. The light of the laser point is imaged within the measuring range of the measuring head on a CCD line (charge coupled device) via an optical system. The axis of the optical system is locked on a fixed angle to the outlet direction of the laser beam. By analyzing the position with the highest light intensity on the CCD line and based on the fixed geometrical relationship (triangulation), the position can be converted to a distance with the help of the calibration curve stored in every measuring head. The configuration for high-precision determination of the outside diameter and the profile consists of several individual sensors arranged in pairs opposite to each other. Simultaneous determination of the distances of all sensors to the surface of the material supplies the basic information needed for further calculation of the tube profile. Configuration with 18 sensors mean diameter At the end of the processing chain the following parameters are displayed, and process correcting variables derived as result: minimum and maximum diameter and their directional position ovality and evaluation of certain structures such as true triangular or hexagonal shapes Diameter, ovality and false-color profile TECHNICAL DATA SINGLE MEASURING HEAD TECHNICAL DATA PROFILE MEASUREMEN Measuring head measurement range 200 mm (standard version) Stand-Off Distance 100 mm Resolution 10 µm Measuring frequency 2000 1/s Wavelength 635 … 670 nm (visible red) Laser class 3R / 3B Minimum diameter > 20 mm Diameter range with up to 400 mm diameter change possible (freely configurable) Measuring accuracy diameter < ± 25 µm Measuring accuracy ovality< ± 50 µm 18-Channel diameter profile measuring system LIMAB laser triangulation sensor 10 11
