Thickness measurement
The main area of operation for laser sensors in the wood industry is thickness measurement. Thickness measurement in the form of an one-track-system is possible with one as well as with two sensors. Measuring with one sensor is carried out on a reference cylinder as a basis. In this connection, the fact that the cylinder’s ovality as well as any lifting of the product from the cylinder will be registered as a change of thickness and can lead to measuring errors needs to be taken into consideration.
Therefore, the standard use of two laser sensors per measuring track is recommended, whereby one sensor each is positioned above and below the product. This arrangement allows for a vertical movement of the product within the measuring range, which will have no influence on the measuring result. Depending on the sensors’ arrangement and number, there is thus a possibility of different system configurations
- stationary thickness measurement of 1 to x tracks
- thickness measurement with adjustable measuring tracks
- traversing thickness measurement
Special data processing units or system solutions with a PC are available for stationary thickness measurement. Different traversing stands in the form of C or O frames of different widths are used for the traversing measurement. The traversing enables the continuous detection of longitudinal and transverse profiles and, in addition, the width measurement for product lines that do not migrate.
Trussing errors caused by manufacturing tolerances and the bending of the trussing due to its own weight are compensated for by a corresponding trussing error correction.
Single-track laser thickness measurement system for the wood industry with OPTImess-H laser sensors and OPTIcontrol data processing unit:
The OPTIcontrol data processing unit enables the connection and processing of 2 OPTImess-H laser sensors. During the thickness measurement, the 2 sensors are processed at the same time, so that even a vertical movement of the product to the measuring axis does not lead to falsification of the thickness measurements.
The standard thickness measurement software enables the following points:
- Calibration of the system with any thickness standard
- Online thickness measurement with 2 sensors
- Online thickness measurement with 1 sensor against a reference