单板热板干燥技术初探

<正>枫香树(Liquidambar formosana Hance)是我国南方山区常见的阔叶树,在贵州遍及全省。枫香树自然繁殖力强,生长快,树干通直高大,木质细致均匀,切削性能好。但是枫香木材的干缩系数及其变异都较大,纹理斜至交错,是干燥性能极差的木材之一。 近年来,国外出现了用“热板干燥厚单板”的新技术,美国惠好公司(Weyerhaeuser)和芬兰劳泰(Ratue)公司用特制的热板干燥机干燥厚单板(3.2mm以上),效果良好。据称具有干燥速度快,干燥质量好,节省能源35～50％,提高单板出材率5～10％,安全可靠等优点。 我们仅对枫香薄单板热板干燥技术探讨如下。

A STUDY ON A NEW TECHNIQUE OF DRYING VENEER WITH HOT BOARD

Liquidambar formosana Hance, a kind of hard tree, is widely spread in the south of China. They cover the whole province of Guizhou with great potentialities. Its trunk is upright and tall, and the timber is fine, smooth and even with good cutting property. However, its dsying property is not good at all. It is easy to split and warp. It has long been regarded as useless. When veneer is dried with usual method for making plywood, it also splits and warps. And there are always curves in mid-part of the board. While the edges are in shape of lotus leaves so the plywood is of low quality and the following process will be difficult. Such plywood is easy to split and pile up. The core veneer seuers seriously. Its qualify rate is very low.However, with hot-pressing method, the veneer is level, smooth and soft ;thc shrinkage in rotatory direction will be lowered from about 10% to l.5%; splits will decrease from 60% to 70%. The first and second class veneer may reach as much as 70% and save 7% of veneer. The method can also be applied to Schima confertiflora, Cinnamomum camphora and many other hard wood veneer. Its strength will not be influenced. The key to this technique is how to choose the structure of exhaust caul board and how to drain away the juice and steam of veneer in this process of veneer drying. After many kinds of experiments on boards ,the GL-18 which we have chosen can be easy obtained, the processing is simple with lower cost and better utility.