Abstract
Ten plain-sawn boards of Scots pine (Pinus sylvestris L.) were compressed semi-isostatically according to the CaLignum process in a Quintus press at 25°C and 140 MPa. X-ray computerised tomography images of the same cross-sections were captured before and after compression and compared using a transformation algorithm. In the algorithm the shape of compressed cross-sections were converted to the same shape as non-compressed using the density variation between pixels. Density after compression and the increase in density were analysed using PLS regression. The regressor variables described position in the cross-section and wood properties of each pixel. Heartwood and other resinous wood were less compressed than sapwood, particularly in boards with high resin content. Density also increased little close to the press table, especially in whorls with large knots. Higher original density gives lower degree of compression but still higher density after compression.
Zusammenfassung
Zehn plangesägte Kiefernbretter (P. sylvestris L.) wurden semi-isostatisch nach dem CaLignum-Prozess in einer Quintus-Presse bei 25°C und 140 Mpa verdichtet. Röntgen-CT-Bilder identischer Querschnitte wurden vor und nach Verdichtung aufgenommen und mit Hilfe eines Transformier-Algorithmus verglichen. Die Form des verdichteten Querschnitts wird dabei in das ursprüngliche Format des unverdichteten Querschnitts umgewandelt, wofür die Dichtevariation zwischen den Pixeln herangezogen wird. Die Dichte nach Kompression und der Dichteanstieg wurden mittels PSL-Regression analysiert. Die Regressions-Variablen beschreiben Position und Eigenschaften jedes einzelnen Pixels. Kernholz und anderes harzhaltiges Holz wuden weniger verdichtet als Splintholz, insbesondere bei Brettern mit hohem Harzgehalt. Die Dichte stieg in der Nähe des Presstisches nur geringfügig an, vor allem im Bereich von Astquirlen mit hohem Astanteil. Bei höherer Ausgangsdichte ergab sich nach der Kompression ein geringerer Verdichtungsgrad, wenn auch bei höherer Enddichte.
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Blomberg, J., Persson, B. An algorithm for comparing density in CT-images taken before and after compression of Pinus sylvestris. Holz Roh Werkst 63, 23–29 (2005). https://doi.org/10.1007/s00107-004-0544-4
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DOI: https://doi.org/10.1007/s00107-004-0544-4