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120 m/min with little space

Presorted logs are stored on the log yard prior to debarking.
The chipper canter from the existing sawline was integrated in the LINCK line.
Good cooperation: Derome Timber production manager Per Andersson with project engineer Daniel Betzold from Linck (from left)
The infeed system transports the two-sided cant into the chipper canter and is important for curve sawing.
Profiling can also be done asymmetrically which increases recovery.
The profilers have three steps - the circular sawblade improves surface quality.
A precentering as well as centering units are installed in front of the two profiler units.
A tool change before the afternoon shift is a must prior to continue production with 120 m/min.

There is not much space available at Derome Timber in Veddige, Sweden. However, despite the restricted space and already existing machines that had to be integrated into the new process, production at 120 m/min. feed speed is now possible in the short sawmill building. Increasing the feed speed to 150 m/min. will be possible after having upgraded the upstream debarking machine.

There is a difference whether you can build up a greenfield sawmill or whether you have to live with a 70 m short sawmill building. The German machine manufacturer LINCK Holzverarbeitungstechnik, Oberkirch accepted this challenge at the Swedish sawmill Derome Timber in Veddige. Another difficulty that came up was the integration of existing machines into the new production flow.

The first preliminary investigations showed that the restricted space available represented a real obstacle. But finally the effort paid-off. Today a saw line is operating in two shifts and at 120 m/min. feed speed.

Every centimetre counts . The log yard of Derome Timber shows the normal workflow. After having passed the loading and unscrambling conveyors, the logs are turned for transport into a butt end reducer taking off the butt flare. A scanning system then determines log length, diameter and even quality. A metal detector examines the logs with regards to metal inclusions before they are stored. Another operating mode is the processing of unsorted logs where they are fed to the saw line directly from the sorting plant. A ring debarker takes off the bark from the sorted spruce logs during longitudinal transport. The existing Rema-scanner, still part of the new production sequence, takes care of the log pre-optimisation and supplies data for the breakdown control.

The logs are turned, centred and fed to the first chipper canter. The breakdown saw unit takes off up to two sideboards on the left- and right-hand side which are then transported to the board edger. The remaining two-sided cant is then fed to a single-rotor cant turner DV70 which is the first Linck supplied part of the saw line. According to Daniel Betzold, project engineer and person in charge of the project from the beginning, "it is possible to install a second rotor in case of a capacity increase".

The following roller conveyor is so short that the cants nearly arrive at the infeed system of the second chipper canter before they are released by the cant turner.

Here it is obvious for the viewer how restricted space really is. The second chipper canter, which had to be moved by 1.5 m only, was also taken from the existing downstream production line. The scanning system directly behind the machine has two targets: determining the cant shape for the following profiling and controlling the curve produced. Curve control is carried out by a newly developed scanning system Linck 7 which can be installed in a restricted space and which compensates the cant movement during measuring. Daniel Betzold: "Curve sawing is important for recovery as nearly every log shows a certain curve."

The sideboard optimisation system calculates sideboard dimensions and positions based on the 3D-scanning data. It is possible to produce different dimensions and a different number of sideboards on the left- and right-hand side. A roller conveyor leads the cants to a precentering system and then further on to two profiler units VPF.

To know the ropes / Optimised curve sawing. The last machine in the line is the circular resaw CSMK 285-A3/B3. The sawblade diameter used determines the limits for curve sawing, i.e. the smaller the blade diameter, the bigger the curve to be sawn. This workflow is realized by the in- and outfeed systems VZO which guarantee an accurate path control by linear guided and actively controlled feed rollers. Typical radii range from 80 to 100 m. The lumber is then transported to the sorting plant from where it goes to stacking and drying facilities supplied by C. Gunnarssons Verkstads. Nearly 100 % of the lumber produced are planed.

The disadvantage of the former production flow was that the board edger had to handle boards from primary and secondary cut and that its capacity was therefore not sufficient for such a large quantity of boards. With this investment it was possible to increase production from 190.000 m³ to 250.000 m³ lumber which resulted in a 2% higher recovery. Derome Timber also produces finger-jointed timber, profiled timber, timber panels and construction timber, briquettes as well as components for prefabricated houses.

Best references. According to Per Andersson, production manager and responsible for every production step in the plant: "The company's good reputation and the accurate work of the resaw were decisive for choosing Linck as partner." In the future Derome Timber will handle more small diameter logs. Andersson is convinced that "more small diameter logs will be available for the sawmill industry by the decreasing paper production". In case average diameters continue to decrease, Derome is already thinking about adapting the preceding and following parts of the plant for running the saw line at 150 m/min. feed speed.

Derome Timber

Location Veddige/SE
Production Manager Per Andersson
Employees (sawmill group) 800
Production capacity 250.000 m³ lumber/year
Species Spruce
Main markets Sweden, England
Products Lumber, planed timber, profiled timber, finger-jointed timber, pressure-impregnated timber, pellets, briquettes, chips, timber panels, construction timber and components for prefabricated houses.