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題名 | 方榫接合強度之研究=Studies on the Bending Moment of Mortise and Tenon Joints |
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作者 | 楊明津; | 書刊名 | 木工家具雜誌 |
卷期 | 165 1998.04[民87.04] |
頁次 | 頁90-98 |
分類號 | 474.3 |
關鍵詞 | 榫頰比; 榫寬比; 榫厚比; 括拭作用; 彎矩; |
語文 | 中文(Chinese) |
中文摘要 | 本研究針對榫長 tl、榫寬 tw、榫厚 tt、X 嵌合度、膠合劑與接合類型等因素, 探討其對於方榫接合最大彎矩值的影響,獲得結果如下: 榫長因素對於方榫接合最大彎矩值成二次曲線正關係, 在榫頰比 tcr=0.6 後,對於最大彎 矩值的貢獻度趨緩,以層積試件的實驗結果推論,發現此現象係方榫接合刮拭作用與逆滲作 用交互影響的結果。 榫寬因素對於方榫接合最大彎矩值成直線正關係, 並發現其影響斜率隨榫頰比 tcr 增加而 提高,tcr=1.0 時的影響斜率為 85.25,tcr=0.6 時的影響斜率為 76.81,tcr=0.4 時的影 響斜率為 41.84,其影響斜率的提高在榫頰比 tcr=0.6 後亦形趨緩:亦即 tcr=1.0 時,榫 寬 tw 的影響斜率比 tcr=0.6 時上升的幅度有限。 方榫接合承受荷重外力時, 合力 t 與 c 的距離 e 值決定榫寬 tw 與橫檔寬度 rw 的比例 ,筆者將此關係稱為榫寬比 twr,tw-tw/rw,由推論與實驗結果得到 e=0.62tw+0.05rw,且 橫檔寬度 rw 不變時,twr=1.0 可獲得最大的彎矩值。榫厚因素對於方榫接合最大彎矩值成 二次曲線關係,當榫厚 tt 與橫檔厚度 rt 的比例為 0.5 時, 可獲得最大的彎矩值,筆者 將此關係稱為榫厚比 ttr,ttr=tt/rt。 X 嵌合度採過盈配合,對於方榫接合最大彎矩值不具實質貢獻,大於 +0.3mm 留隙配合,對 於最大彎矩值則有減弱現象, 並得填縫性膠合劑的 X 嵌合度宜採 -0.10mm ∼ +0.26mm 的 過渡配合,非填縫性膠合劑則應採 -0.26mm ∼ +0.10mm 的過渡配合。 膠合劑的固成份對於方榫接合最大彎矩值具顯著影響性,以固成份 66.7 %尿素膠粉為基準 ,則固成份 46.5 %愛瑪膠達到 82 %的最大彎矩值,而固成份 35 % PVAc 膠只達 55 % 的最大彎矩值。 圓端方榫接合抗彎強度為直端方榫接合最大彎矩值的 89 %,此係前者邊木理膠對邊木理膠 合面積減少所造成。 短榫接合、L 型方榫接合與附木釘鍤銷方榫接合均容易造成立柱構件或榫頭構件劈裂現象, 因此木材縱向抗剪強度對於方榫接合的最大彎矩值具有重要影響性。 本研究以多元迴歸分 析與影響係數,導出方榫接合最大彎矩值的計算方程式為: M=S �滿� (-52.20+1.24tl-0.014tl �� +0.434tw+0.035rw+111.25ttr-112.66ttr �� ) × a × b × c 其中 M 表示方榫接合最大彎矩值( kgf-cm ),S �漯磳� MC=12 %時木材的縱向抗剪強度 ( kgf/cm �插^, tl 表示榫長( mm ), tw 表示榫寬( mm ),rw 表示橫檔寬度( mm ),ttr 表示榫厚比( ttr=tt/rt ),a 表示 X 嵌合度係數,b 表示膠合劑係數,c 表示 方榫接合類型係數。 |
英文摘要 | In this research, we want to study the factors of the mortise-and-tenon joints on the bending strength. We will use the factors of tenon length, tenon width, tenon thickness, X-fit, adhesive and the type of joints to study this problem. The factor of the tenon length and the bending strength of the mortise-and-tenon joints have a quadratic relation; the bending strength increases as the length is longer. But this increase will slow down when the tenon cheek ratio (tcr=tl/tw) is greater than 0.6 From the result of the laminated specimen testing, we found that this phenomenon was caused by the cross-effect between of wiping action and permeation action when the joint was assembled. The factor of the tenon width and the bending strength of the mortise-and-tenon joints have linear relation; the bending strength increase as the tenon is wider. When there is external force on teh mortise and tenon joints, the distance between the tensile resultants-t and teh compressive resultants-c depends on the ratio of tenon width (tw) and the rail width (rw), twr=tw/rw. From the result of experiment, we get the equation e=0.62tw+0.05rw. When the rail width fixed and twr=1.0, we can get the maximum bending strength. The factor of tenon thickness ratio-ttr (ttr=tt/rt) and the bending strength of mortise-and-tenon joints have a quadratic relations. When ttr=0.5, we can get the maximum bending strength. The interference-fit on the X-fit is not a substantial effect to the bending strength of the mortise-and-tenon joints. If the sliding-fit is greater than + 0.3mm, it will reduce the bending strength obviously. The suitable X-fit of gap-filling adhesive should be use the transition-fit from -0.1mm ∼+0.26mm. The suitable X-fit of non-gap-filling adhesive should be use the transition-fit from -0.26mm ∼+0.1mm. The solid content of the adhesive has significant inference to the bending strength of the mortise-and-tenon joints. the bending strength of the 46.5% solid content-Elmer adhesive can be 82% of the 66.7% solid content-UFP adhesive, but the bending strength of the 35% solid content-PVAc adhesive will only be 55% of the 66.7% solid content-UFP adhesive. The bending strength of the round-end-mortise-and-tenon joints is 89% of the bending strength of the square-end-mortise-and-tenon joints, because the glue area of side-grain-to-side-grain of the former is less than the latter. The short-tenon type joints, L-type joints and doweled-tenon type joints are all tend to split the post member or the tenon member. Therefore, the shear-parallel-to-the-grain of wood has very important influence to the mortise-and-tenon joints. In this research, we use multiple regression to derive the equation of the bending strength of the mortise and tenon as bellow: M=S �滿� (-52.20+1.24tl-0.014tl �� +0.434tw+0.035rw+111.25ttr-112.66ttr �� ) × a × b × c where M=the bending moment of the mortise-and-tenon joint (kgf-cm) tl=tenon length (mm) tw=tenon width (mm) rw=rail width (mm) ttr=tenon thickness ratio a=the coefficient of the X-fit b=the coefficient of the adhesive type c=the coefficient of the type of joints S �� =the shear-parallel-to-the-grain of wood (kfg/cm �� ) when MC=12% |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。