Cut length control on roll-fed material

Determining the length and velocity provides the basis for controlling the cut length. If the sheet materials are not to be stopped in order to perform the cut, then the cutting device must move along with the sheet material for a straight cut, in other words it should be a "flying cutting device". The speed of the sheet material is measured for velocity synchronization

Laser surface velocimeters (LSVs) from Polytec are ideally suited for cut length control because they measure both velocity and length at the same time and can display the values on different interfaces. The LSVs work on almost any surface and they are not susceptible to contaminated surfaces. The non-contact measuring technique makes it possible to eliminate any negative influences on accuracy, such as slippage and wear, simultaneously. The product being subjected to the measurement also remains intact.

The Polytec LSV offers increased cutting precision compared to other methods and therefore allows a reduced safety margin to be added to the preset cut length. This will save costs on every cut. Another benefit of Polytec systems is the flexible interface concept – it enables length and velocity readings via encoder output, serial interfaces, LAN, Profibus and Profinet. The digital outputs feature a pre-warning signal that indicates when the cutting length is about to be reached, as well as the cut signal for triggering the cutting process.

Practical examples

In the wood and construction material industry Polytec LSVs are used to control cutting lengths in cut-to-length processes for, e.g. wood & wood products, plasterboard, glass wool and mineral wool.

Industrial length and speed control with optical sensors

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