木材焊接理论研究及技术进展

Theoretical Research and Technical Progress of Wood Welding

介绍了木材焊接技术的研究进展,包括焊接原理、两种焊接形式分类、影响参数、焊接过程中的化学变化、焊接理论模型研究以及焊接技术的应用等。在焊接形式分类中分别介绍了平面的摩擦焊接和木榫旋转焊接过程及伴随的温度变化。在影响参数中综述了树种、纹理、焊接速度以及一些特殊处理方法对焊接性能的影响,其中树种和基材纹理方向对平面摩擦焊接性能的影响甚大,树种和木榫转速是影响木榫旋转焊接性能重要参数。在焊接过程化学组分的变化中,着重阐释了木素分解产生的游离酚以及糖类热解产物是粘结性能良好的主要原因,说明耐水性的由来和焊接产生的气体组分。对焊接理论模型的研究较少,尚未获得准确率较高的模型。最后,结合木材焊接技术的优、缺点及研究现状,提出其在现代木结构建筑中替代钉连接,以及古建加固和修复、名贵木材的无胶连接等方面的应用设想。

Research progresses in wood welding were reviewed from the aspects of mechanism,classification of two forms of wood welding,factors affecting wood welding,chemical changes during welding,welding theoretical model,and the application of wood welding. For the classification of wood welding,planar fric tion welding and wood dowel welding as well as the temperature changes involved were introduced. Factors affecting the wood welding included wood species,wood grain,speed of welding,and some special methods, in which wood species and wood grain demonstrated strong influences on planar friction welding, while wood species and wood tenon were key parameters for wood dowel welding. Chemical changes during wood welding included the decomposition of lignins and saccharides to produce free phenolic compounds and those from the decomposition of saccharides,which were the main causes for the enforcements of bond pcr formance and hydrophobic properties, smoke constituents produced from wood pyrolysis were also dis cussed. Researches in theoretical model of wood welding were rare,resulting in the lack of models with high accuracy. The advantages and disadvantages of wood welding and relative researches were discussed. Sever al assumptions about the application were presented, such as replacing screw connection of modern wood structure,reinforcing and repairing ancient architecture, and connecting joints without adhesive of rare wood.