“鋸－乾－剖”加工方法對降低橡膠木6cm正角材翹曲之功效

The Efficiency of Saw-Dry-Rip Process on Reducing Warp of Rubber Wood 6cm Square

翟思湧(Sy-Yung Jai)

《林業試驗所研究報告季刊》 1卷2期 (1986/12) Pp. 177-192

https://doi.org/10.7075/BTFRI.198612.0177

摘要

本研究旨在探討「鋸－乾－剖」(Saw-Dry-Rip，SDR)加工方法是否可有效降低橡膠木製品翹曲之發生。SDR之加工程序為先將小徑原木「連續鋸製」為盤木(flitches)，隨即將盤木進行高溫或傳統窯乾，然後再縱剖為需要尺寸。本研究之處理有三：(l)CC＝傳統製材，傳統窯乾；(2)SC＝連續製材，傳統窯乾；(3)SH＝連續製材，高溫乾燥，試材之最後尺寸為6cm正角。
結果顯示：SC與SH之平均翹曲均較CC（對照）為低，SDR具有降低翹曲之功效；SC與SH之無翹曲試材收率亦均較CC為高；SH比SC節省乾燥時間與能源；SC與SH之強度性質與CC相比無顯著性之差異；在室內自然狀況下，高溫乾燥材(SH)之含水量變化較傳統窯乾(SC，CC)為緩和。

關鍵字

鋸－乾－剖 ； 翹曲 ； 連續製材 ； 求品製材 ； 求品製材（傳統製材） ； 高溫乾燥 ； 橡膠木 ； 正角材 ； 生長應力

並列摘要

The Saw-Dry-Rip (SDR) process was developed by the Forest Products Laboratory, Madison, Wis., USA, to reduce warpduring lumber manufacturing and drying. It is used on low- and medium-density species such as aspen and yellowpoplar which are prone to warp because of longitudinai growth stress. Most previous studies indicated that SDR, especially along with high-temperature drying, has the ability to reduce warp in processing small diameter hardwoods for structural lumber. The SDR process consists of live-sawing logs through and through on the same plane into flitches, drying them, and then ripping to final dimensions.
The objective of this research was to evaluate the efficiency of SDR in reducing warp of 6cm square from Rubber wood. Twenty sample bolts, 120cm in length, 35cm in diameter, cut from three 35-year-old Rubber trees in Chai-Yi, southern part of Taiwan. were used for this study. The effects of two sawing methods, grade-sawing (conventional-sawing) and live-sawing (through and through on one plane), and two drying methods, conventional-drying (T8-D4, below 83℃) and high-temperature drying (mixture of steam and air process, 110℃) were compared in three treatment groups:
A). CC=Conventional sawing/conventional drying.
B). SC=SDR live sawing/conventional drying.
C). SH=SDR live sawing/high temperature drying.
The final cut size of the test board was 6×6×120cm.
The data showed that for Rubber wood:
1). Live-sawing, whether with conventional or hightemperature drying, produced straighter 6cm squares than conventional-sawing. SC treatment reduced warp about 72 percent over the CC control, and SH treatment reduced warp almost 71 percent (Table 4.).
2). SH and SC showed the least amount of warp, with 65.39 percent and 65.31 percent, respectively, of the sample boards having zero warp. While CC control only had 37.34 percent with zero warp (Table 3.).
3). Treatment SH reduced drying time over 54 percent and saving energy over 16 percent compare to CC; and about 70 percent and 31 percent reduction in drying time and power consumption respectively compared to SC (Table 7.).
4). The volume yield of 6cm square with zero warp for SH and SC were both higher than CC (Table 5.).
5). Though high-temperature dried material (SH) showed slightly lower values in MOR, MOE, hardness on longitudinal surface, and impact bending than conventional-temperature dried material (CC and SC), the differences between SH and CC were not significant at 0.05 level, with the exception of hardness. In addition, no statistically significant differences between treatment were found in all the rest items tested (Table 8.).
6). The moisture movement for high-temperature dried material (SH) was significantly slower than conventional-temperature dried ones (Table 9.).
7). The problems of warp in Rubber wood lumber can be greatly reduced by using the SDR process.
8). SDR process appears to be a economical approach to utilizing warp-prone young-growth Rubber wood; and it should be tried with some other small diameter hardwood species to demonstrate their utility as furniture making or structural material.

並列關鍵字

Saw-Dry-Rip ； SDR ； live-sawing ； grade-sawing ； high-temperature drying ； Rubber wood ； squares ； growth stress