Precise detection of velocity and length on wood and construction materials

Length measurement on roll-fed material and piece goods

Determining the velocity provides the basis for measuring the length. The length is calculated based on the velocity profile while the measured object passes through the measuring location..

A laser surface velocimeter (LSV) independently recognizes whether the material is in the measuring location and can start/stop the length measurement accordingly. To achieve maximum measurement accuracy the LSV offers you the option of connecting light barriers as a means of starting or stopping the length measurement. This means you can link up several light barriers with one another to obtain a variety of application options. This may include, for example, controlling the length measurement using both trigger inputs, thereby increasing accuracy

Laser surface velocimeters (LSVs) from Polytec are ideally suited because they can conduct measurements 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.

Another benefit of Polytec systems is the flexible interface concept – it enables length readings via encoder output, serial interfaces, LAN, Profibus and Profinet.

Practical examples:

Polytec LSVs are used for a variety of length measurement processes in the wood and construction materials industry:

• in the winding of sheet materials
• monitoring cut lengths, e.g. on fiber cement, plasterboard, wood and wood products, glass wool, mineral wool and roofing material

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.

Position tracking on sheet materials and piece goods

Position tracking plays an important role in the wood and construction materials industry if a certain position on the object being measured is essential to the process.

A laser surface velocimeter (LSV) measures the length that the object being measured covers until a defined event occurs. The length measured is then used to correlate the event to the corresponding position on the object. One example of this is flaw site detection in non-destructive materials testing.

The Length measurement can also trigger a working step at regular intervals in the process, e.g. printing labels, attaching lettering and logos or marking flaw sites.

LSVs from Polytec are ideally suited because they can conduct measurements 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 remains intact too.

The increased accuracy of velocity and length measurement allows you to determine positions with increased precision. As a result you are better able to adhere to the end product requirements. The result: You increase quality while at the same time reducing waste.

Practical examples:

Polytec LSVs are used for various position detection tasks in the wood and construction materials industry.