微型齿榫纵向接合的初步试验

<正> 一、前 言 微型齿榫接合通常是指齿榫长4-15毫米、齿尖厚0.2-0.4毫米、齿距2.5-4毫米的齿榫接合,原理与一股齿榫(大齿)接合相同。微型齿榫由于齿长缩短, 具有一系列优点:(1)可以节约木材、胶料、刀具材料,减少切削齿榫时的动力消耗;(2)缩小对接部分,得到高于一般齿榫(大齿)的接合效率;(3)适用范围大,适用于大断面材、小断面材以及纵向接长和角度接合;(4)由于齿数多,故可用较高端向压力接合,减小胶合误差,同时不易产生一般齿榫接合时易发生的齿根部分开裂现象;(5)微型齿榫啮合时,机械接合力大,有利于胶合等工序的操作。

A PRELIMILARY EXPERIMENT ON THE LENGTHWISE MINI-FINGER JOINT

Experiments were made to test the strength of the mini-finger joint of eastern larch (Larix laricina) joined lengthways. The length of the mini-finger was 13.5mm, the space between fingers 4mm and the width of the finger groove 0.4mm.Results of the experiments showed that the value of static bending strength of the joint was closely related to the kinds of adhesives and urea-resin adhesive advisable btought about a better effect than polyvinyl acetate resin adhesive and other adhesives. The joining pressure from both ends is about 80-90kg/cm2. The load car pacity of the specimen in vertical direction prevails over that in horizontal. In addition, a modulus of the elasticity in the static bending of the specimen is also given.The experiments showed that the value of the static bendind strength of this joint was higher than that of the common finger joint (the length of which is 32.5mm), and the increase was 19.8 per cent. This joint saves materials (wood and adhesives) and cutting tools and is applicable to a wider range.