1、什么是膠合板？

膠(jiao)合板(ban)(ban)(ban)(ban)(ban)是一(yi)種人造板(ban)(ban)(ban)(ban)(ban)，是將原木沿年輪方(fang)向旋(xuan)切成大張單(dan)(dan)板(ban)(ban)(ban)(ban)(ban)，經(jing)干燥、涂(tu)膠(jiao)后按相鄰單(dan)(dan)板(ban)(ban)(ban)(ban)(ban)層(ceng)木紋方(fang)向相互垂直(zhi)的(de)原則(ze)組坯、膠(jiao)合而成的(de)板(ban)(ban)(ban)(ban)(ban)材。單(dan)(dan)板(ban)(ban)(ban)(ban)(ban)層(ceng)數為(wei)(wei)(wei)奇數，一(yi)般為(wei)(wei)(wei)三層(ceng)至十(shi)(shi)三層(ceng)，常(chang)見的(de)有三合板(ban)(ban)(ban)(ban)(ban)、五合板(ban)(ban)(ban)(ban)(ban)、九合板(ban)(ban)(ban)(ban)(ban)、和十(shi)(shi)三合板(ban)(ban)(ban)(ban)(ban)（市場上俗稱(cheng)為(wei)(wei)(wei)三厘板(ban)(ban)(ban)(ban)(ban)，五厘板(ban)(ban)(ban)(ban)(ban)，九厘板(ban)(ban)(ban)(ban)(ban)，十(shi)(shi)三厘板(ban)(ban)(ban)(ban)(ban)）。外層(ceng)的(de)正面(mian)單(dan)(dan)板(ban)(ban)(ban)(ban)(ban)稱(cheng)為(wei)(wei)(wei)面(mian)板(ban)(ban)(ban)(ban)(ban)，反面(mian)的(de)稱(cheng)為(wei)(wei)(wei)背板(ban)(ban)(ban)(ban)(ban)，內層(ceng)板(ban)(ban)(ban)(ban)(ban)稱(cheng)為(wei)(wei)(wei)芯板(ban)(ban)(ban)(ban)(ban)。

2、分類：

一類(lei)膠合板(ban)為耐(nai)(nai)氣候、耐(nai)(nai)沸水(shui)膠合板(ban)，由此及彼(bi)有(you)耐(nai)(nai)久、耐(nai)(nai)高(gao)溫，能蒸(zheng)汽處理的優點；

二類膠合板(ban)為耐水(shui)膠合板(ban)，能在冷水(shui)中(zhong)浸(jin)漬和短時(shi)間熱水(shui)浸(jin)漬；

三類膠合板為(wei)耐潮膠合板，能在(zai)冷水中短時間(jian)浸漬(zi)，適于室內常溫下使(shi)用(yong)。用(yong)于家具和(he)一般建筑用(yong)途(tu)；

四類(lei)合板為不耐潮膠合板，在室內常態下使用(yong)，一般(ban)用(yong)途膠合板用(yong)材有櫸木(mu)(mu)、椴(duan)木(mu)(mu)、水曲柳、樺木(mu)(mu)、榆(yu)木(mu)(mu)、楊木(mu)(mu)等。

3、對稱原則：

對(dui)稱(cheng)(cheng)中(zhong)心平(ping)(ping)面兩側(ce)的(de)(de)單(dan)(dan)(dan)板(ban)，無(wu)論樹種(zhong)，單(dan)(dan)(dan)板(ban)厚(hou)度、層數、制造方(fang)法、纖維方(fang)向(xiang)和單(dan)(dan)(dan)板(ban)的(de)(de)含(han)水(shui)率都應(ying)該互相(xiang)(xiang)對(dui)應(ying)，即對(dui)稱(cheng)(cheng)原則。膠(jiao)合(he)板(ban)中(zhong)心平(ping)(ping)面兩側(ce)各(ge)對(dui)應(ying)層不(bu)同方(fang)向(xiang)的(de)(de)應(ying)力大小相(xiang)(xiang)等。因此，當膠(jiao)合(he)板(ban)含(han)水(shui)率變(bian)化時，其結(jie)構穩定(ding)，不(bu)會產(chan)生變(bian)形(xing)，開(kai)(kai)裂(lie)等缺陷(xian)；反之(zhi)，如果對(dui)稱(cheng)(cheng)中(zhong)心平(ping)(ping)面兩側(ce)對(dui)應(ying)層有某些差異，將會使對(dui)稱(cheng)(cheng)中(zhong)心平(ping)(ping)面兩側(ce)單(dan)(dan)(dan)板(ban)的(de)(de)應(ying)力不(bu)相(xiang)(xiang)等，使膠(jiao)合(he)板(ban)產(chan)生變(bian)形(xing)、開(kai)(kai)裂(lie)。

4、奇數層原則：

由于膠(jiao)合(he)板(ban)的結構是相鄰層單板(ban)的纖維方(fang)向互相垂，又必須符合(he)對稱原(yuan)則(ze)，因此它的總(zong)層數(shu)必定(ding)是奇數(shu)。如：三層板(ban)、五層板(ban)、七(qi)層板(ban)等。奇數(shu)層膠(jiao)合(he)板(ban)彎曲時大的水平剪(jian)應力作(zuo)用(yong)在(zai)(zai)中心單板(ban)上，使其有較大的強度。偶數(shu)層膠(jiao)合(he)板(ban)彎曲時大的水平剪(jian)應力作(zuo)用(yong)在(zai)(zai)膠(jiao)層上而不是作(zuo)用(yong)在(zai)(zai)單板(ban)上，易使膠(jiao)層破壞，降低(di)了膠(jiao)合(he)板(ban)強度。