Measuring systems for tubes

ONLINE MEASUREMENT IN A PILGER MILL

THE REQUIREMENTS

Photo: V+M Tubes
Photo: V+M Tubes

Given the small batch sizes, a fast measurement of the tube diameters is important to ensure fast feedback of the measured data into the process. This is important to keep the required tight tolerances.

Due to the high tube temperatures manual measurement of each tube is not possible. However, particularly during set-up of the mill the online measurement of each tube is important to rapidly reach the required tolerances.

 

The solution

The measurement principle: shadow size

The TDMS system precisely measures the tube diameters online in two axes after the rolling stand and thus ensures the complete verification of the diameters over the entire length of each tube.

CCD cameras arranged in two axes “see” the tube as black shadow in front of bright sodium back lights. The tube diameters are then calculated from the shadow sizes.

Please click here to read the complete application report.

ONLINE MEASUREMENT OF „HIGH COLLAPSE“ PIPES

THE REQUIREMENTS

"High Collapse" tubes are subject to the highest quality standards. Each tube must be checked individually and its collapse load must be computed, based on parameters like minimum, average and maximum outer diameter, wall thickness, out-of-round and eccentricity. As part of a continuous improvement strategy, the manual data acquisition and the accuracy of the manual sample measurements used for this computation should be improved.

Extending the scope of these measurements, yet reducing the efforts, V & M decided to establish an online control of the "high collapse" tubes. A new measurement system for diameter, out-of-round and length of the tubes would complement the existing ultrasound wall thickness measurement system and create a "digital finger print" of every single tube for computation of its collapse threshold. Furthermore, V & M customers require especially tight tolerances for the tube ends to optimally match other tubes. This will avoid flow turbulences in the pipes and thus increase the capacity. All measurements should be carried out fully automatic within the cycle time of the plant. Last not least, the new system should fit in the existing plant equipment without major modifications.

 

The solution

The measurement principle: shadow size

An encapsulated measurement frame incorporating two LAP Laser Scan Micrometers arranged under 90° angle to measure diameter and out-of-round was integrated into the existing feeding conveyor of the US measurement system. The tube length is measured via two laser photocells along a reference distance. Conveyor rolls arranged under an angle of 45° let the tubes spiral through the measurement system, ensuring continuous measurement of the tubes in two axes over the entire length. 

Due to the compact measurement frame, the high measurement accuracy and the simple operation, the LAP solution prevailed over competing solutions using CCD cameras or Structured Light Imaging systems.

Please click here to read the complete application report.

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