Applications

LSV-6000 | LSV-300 | Applications | Principle of Operation

Please find current application notes as PDF-files here

The metals industry has traditionally used contact sensors for speed and length measurement. However, contact sensors can produce undesirable measurement errors because of slippage, wear or chatter. They can also interfere with the manufacturing process and even reduce product quality by scoring or scratching. In harsh environments, contact sensors run the risk of being damaged, and every time a sensor breaks, it results in expensive down-time.
On-line control of continuous casters One of the leading steel producer in Germany decided to use a Polytec Laser Surface Velocimeter after an extensive testing phase. The LSV- 5000 system replaced water-cooled measurement wheels. The purpose of this installation was it to eliminate measurement errors caused by corrosion, dirt and slippage on the measurement wheels Line speed is 0.6 m/min. Surface temperature is 900°C Material thickness ranges from 160 to 270mm
Cut-to-length control of tube & pipe In tube mills the LSV measures the actual tube length and provides data for the cutter control system. Unlike encoder wheels, the LSV data is not affected by slippage or contact problems resulting in higher accuracy when cutting off the desired length. With a depth of field up to 200 mm, mounting the LSV-065 or LSV-026 a fixed distance from the roll train enables measurement of tubes with various diameters. As a result, a remotely-actuated traverse system is no longer required to keep the material at a fixed distance from the sensor.
Length inspection of pre-cut materials There are two possible modes of operation for measuring pre-cut sections: 1. Self-trigger: The Velocímeter Controller is equipped with a "material present" feature which reliably starts or stops the length measurement within 100 µs as soon as the object enters the measurement volume. The edge detection error is typically less than ± 2 mm. Naturally for long lengths, this edge error can be neglected.  2. External trigger: Achieving absolute accuracy by using the LSV system in conjunction with optional, edge-detecting light-barriers.
Length measurement on a continous caster Five LSV 5000 have been installed for control of a flame cutter. The LSV´s are replacing the previous method utilizing photocells. The length accuracy with photocells was limited to a few percent. By incorporating Polytec´s Laser Surface Velocimeter cutting accuracies of < 0.08% are achieved. Line speed is ranging from standstill to 4 m/min. Surface temperature is 900°C
Length measurement in a plate mill The customer requirements for this length measurement system was for a speed range from standstill to 2m/s and also for the reversal speed. The system had to be very heat resistance up to ambient temperature of 200°C Polytec's LSV achieved a length accuracy 50 times better than the prior method of calculating length numerically.
Cut to length control of plastic panels LSV-System with LSV-065 sensor head measures the length of plastic panels with different colors and surface structures. The process I/O interface provides a customer defined output signal which indicates that a pre-selected run length has been reached.
Skin pass and tensile strain measurements Prior to using Polytec LSV´s, speedometer generators at the guide pulleys measured the degree of elongation. Slippage between strip and guide pulley caused errors in the measurement of the elongation. The new elongation control system, based on two LSV´s, completely eliminates such errors and helped a leading quality steel producer to improve the measurement uncertainty to 0.02%.
Differential speed for automatic gauge & elongation control in skin pass mills  The difference in strip speed before and after a roll stand represents the net elongation of the coil. Accurately measuring differential speed is therefore the key to tightening gauge tolerances. Polytec has successfully demonstrated differential elongation measurements with an uncertainty of 0.02% of the sample length In addition to increased accuracy over encoders when the coil runs at constant speed, LSV technology opens up the possibility to perform gauge control during the acceleration and deceleration phases as well. The result is longer finished lengths meeting specified gauge tolerances.
Other applications: Length/speed in hot & cold coil, plate, rod and bar mills Linear length/speed of rotating materials Crop shear optimization Synchronizing fast moving aluminum, brass, bronze and copper strips Speed control in extruding mills