A New Method for Bending Solid Wood: High Frequency Heating of Beech
2005 (English)In: Hardwood research and utilisation in Europe / [ed] Bejo, L., Sopron: University of West Hungary , 2005, 156-161 p.Conference paper (Refereed)
In their natural state, most hardwoods cannot be bent to an appreciably small radius of curvature. This is due to either fracturing or retaining elastic properties sufficient to cause spring back to approximately their original shape on removal of the bending force. But some species when subjected to heat in the presence of moisture (usually by steaming or boiling) become semi-plastic and their compressibility is very increased.
By holding the bended material to shape after bending, and subsequently drying and cooling it, the wood tends to become rigid and “set” almost exactly to the curved shape imposed on it by bending. The rate of production when using traditional methods for solid wood bending is considerably slow and there is request from the industry to reducing the processing time and thereby reducing the production costs.
A new method for solid wood bending is presented in this paper. The method is based on high frequency technique for heating, plasticizing and drying the wood to be bent in one step. One of the purposes to use high frequency heating was to decrease the time of the bending process. In practise this means reducing the time to bend and dry a straight piece of solid wood from a moisture content of about 25 % to 6 – 8 % from about 24 hours to about 10 minutes. This gives high demands on controlling the moisture content, temperature and the strain fields that occur in the wood during bending.
Place, publisher, year, edition, pages
Sopron: University of West Hungary , 2005. 156-161 p.
wood bending, beech, birch, thermo hydro mecahnical processing, high frequency, softening, production
Research subject Technology (byts ev till Engineering), Forestry and Wood Technology
IdentifiersURN: urn:nbn:se:lnu:diva-20949OAI: oai:DiVA.org:lnu-20949DiVA: diva2:542402
The 2nd European Conference on Hardwood. September 6, Sopron, Hungary