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Holz als Roh- und Werkstoff

, Volume 56, Issue 3, pp 171–177 | Cite as

Radially sawn timber. Gluing of star-sawn triangular profiles into form-stable products with vertical annual rings

  • D. Sandberg
  • H. Holmberg
Original

Abstract

A method is presented for the gluing of star-sawn triangular profiles of pine (Pinus silvestris L.) into form-stable wood products with vertical annual rings. The triangular profiles are free from pith and from most of the juvenile wood. The method is based on dried and conditioned triangular profiles. Undesired defects are removed and the wood is finger-jointed into long lengths. In the finger-jointing, consideration is given to the appearance and annual ring orientation of the jointed materials. After the jointing, the triangular profiles are planed and glued into rectangular blocks with vertical annual rings. These blocks can then e.g. be used as construction beams or be sawn up into solid wood panels,

A pilot plant has been built for the manufacture of knot-free solid wood panels based on the proposed method. Results show a total volume yield of 53.8%. Three critical production stages can be distinguished: removal of knots and defects, planing, and division of blocks into boards. These three operations are together responsible for more than 93% of the total losses in the manufacture. The removal of knots and defects meant a volume loss of 12.8%. 13% of the manufactured units were 2.1 m long without finger-jointing and free from knots and other defects. The average length of the remaining pieces used for finger-jointed units was 0.41 m.

Keywords

Timber Annual Ring Volume Yield Angular Error Juvenile Wood 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Sternsägen — Verleimen von sterngesägten Dreikantprofilen zu formstabilen Produkten mit stehenden Jahrringen

Zusammenfassung

Diese Arbeit beschreibt eine Methode zum Verleimen von sterngesägten Dreikantprofilen aus Kiefernholz zu formstabilen Produkten mit stehenden Jahrringen. Die Dreikantprofile sind frei von Mark und überwiegend auch von juvenilem Holz. Verwendet werden getrocknete und konditionierte Profile. Unerwünschte Holzfehler werden ausgeschnitten. Danach werden die Werkstücke durch Keilzinkung längs verleimt, wobei auf das Aussehen und die Ausrichtung der Jahrringe geachtet wird. Nach dem Hobeln werden diese Dreikantwerkstücke zu rechteckigen Blöcken mit stehenden Jahrringen verleimt. Die Blöcke können z.B. für Konstruktionszwecke verwendet oder zu Brettern oder Platten aufgesägt werden. Im Pilotmaßstab werden inzwischen astfreie Platten nach dieser Methode hergestellt. Insgesamt wird eine Volumenausbeute von 53,8% erzielt. Drei kritische Produktionsschritte sind dabei zu beachten: Entfernen der Äste und sonstiger Fehler, Hobeln sowie Auftrennen in Bretter. Bei diesen drei Produktionsschritten fallen über 93% des Massenverlustes an. Das Entfernen der Holzfehler führt zum Verlust von 12,8% des ursprünglichen Volumens. 13% der Werkstücke hatten eine Länge von 2,1 m (astfrei, vor dem Verleimen). Die durchschnittliche Länge der übrigen zum Verleimen verwendeten Stücke betrug 0,41 m.

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References

  1. Holmberg H, Sandberg D (1996) Volume yield and quality of timber when using star-sawing technique. Royal Institute of Technology, Division of Wood Technology and Processing, Report TRITA-TRÄ R-96-22 (in Swedish)Google Scholar
  2. Marian JE, Suchsland O (1956) Waviness of lumber- and chipcore board an investigation of the factors affecting surface stability. Paper and Timber no. 6–7Google Scholar
  3. Peck EC, Selbo ML (1950) Comparison of redwood and flatgrained yellowpoplar for cores in furniture panels. Forest Products Lab. Madison, Report No. 1785Google Scholar
  4. Perry TD (1953) Making Lumber Cores for Plywood. Wood and Wood Products 61(2)Google Scholar
  5. Sandberg D (1995) Vertical Annual Rings in Pine (Pinus sylvestris L.}) and Spruce (Picea abies} Karst), Royal Institute of Technology, Division of Wood Technology and Processing, Report TRITA-TRÄ R-95-13 (in Swedish)Google Scholar
  6. Sandberg D (1996a) The influence of pith and juvenile wood on proportion of cracks in sawn timber when kiln dried and exposed to wetting cycles. Holz Roh-Werkstoff 54:152CrossRefGoogle Scholar
  7. Sandberg D (1996b) Radially sawn timber. Starsawing — a new method for producing timber with vertical annual rings. Holz Roh-Werkstoff 54:145–151CrossRefGoogle Scholar
  8. Sandberg D (1996c) The influence of annual ring orientation on strength and dimensional changes during moisture content changes in finger joints. Holz Roh-Werkstoff 55:50CrossRefGoogle Scholar
  9. Sandberg D, Holmberg H (1996) Radially sawn timber. Kots — number, type and size in starsawn triangular profiles of pine (Pinus sylvestris L.) and spruce (Picea abies Karst). Holz Roh-Werkstoff 54:369–376CrossRefGoogle Scholar
  10. Sandberg D (1997) Radially sawn timber. The influence of annual ring orientation on crack formation and deformation in water soaked pine (Pinus sylvestris L.) and spruce (Picea abies Karst) timber. Holz Roh-Werkstoff 55:175–182CrossRefGoogle Scholar
  11. Selbo ML (1952) Effectiveness of Different Conditioning Schedules in reducing Sunken Joints in Edge Glued Lumber Panels. J. For. Prod. Soc. 2 (1)Google Scholar
  12. Timber Grading Committee (1976) Guiding Principles for Grading of Swedish Sawn Timber, Second edition, The Swedish Timber and Wood Pulp JournalGoogle Scholar
  13. Weslien H (1993) Estimating size and amount of pitchpockets in roundwood. The Swedish University of Agricultural Science. Dept. of For. Prod. Research Notes No 171Google Scholar

Copyright information

© Springer-Verlag 1998

Authors and Affiliations

  • D. Sandberg
    • 1
  • H. Holmberg
    • 1
  1. 1.Dept. of Manufacturing Systems, Div. of Wood Technology and ProcessingRoyal Institute of TechnologyStockholmSweden

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