1、什么是胶合板？

胶合(he)板(ban)(ban)(ban)(ban)(ban)(ban)是一种人造(zao)板(ban)(ban)(ban)(ban)(ban)(ban)，是将原(yuan)木沿年(nian)轮方向(xiang)旋切(qie)成大(da)张单(dan)板(ban)(ban)(ban)(ban)(ban)(ban)，经干燥(zao)、涂胶后按相邻单(dan)板(ban)(ban)(ban)(ban)(ban)(ban)层木纹方向(xiang)相互垂直的(de)(de)(de)原(yuan)则(ze)组坯(pi)、胶合(he)而成的(de)(de)(de)板(ban)(ban)(ban)(ban)(ban)(ban)材。单(dan)板(ban)(ban)(ban)(ban)(ban)(ban)层数为奇数，一般为三(san)层至十三(san)层，常见的(de)(de)(de)有三(san)合(he)板(ban)(ban)(ban)(ban)(ban)(ban)、五合(he)板(ban)(ban)(ban)(ban)(ban)(ban)、九合(he)板(ban)(ban)(ban)(ban)(ban)(ban)、和十三(san)合(he)板(ban)(ban)(ban)(ban)(ban)(ban)（市(shi)场上(shang)俗称为三(san)厘板(ban)(ban)(ban)(ban)(ban)(ban)，五厘板(ban)(ban)(ban)(ban)(ban)(ban)，九厘板(ban)(ban)(ban)(ban)(ban)(ban)，十三(san)厘板(ban)(ban)(ban)(ban)(ban)(ban)）。外层的(de)(de)(de)正(zheng)面(mian)单(dan)板(ban)(ban)(ban)(ban)(ban)(ban)称为面(mian)板(ban)(ban)(ban)(ban)(ban)(ban)，反面(mian)的(de)(de)(de)称为背板(ban)(ban)(ban)(ban)(ban)(ban)，内层板(ban)(ban)(ban)(ban)(ban)(ban)称为芯板(ban)(ban)(ban)(ban)(ban)(ban)。

2、分类：

一类胶合板为耐(nai)(nai)气候、耐(nai)(nai)沸水胶合板，由此及彼(bi)有耐(nai)(nai)久(jiu)、耐(nai)(nai)高温，能蒸汽处理的优点；

二类胶(jiao)合板为耐水胶(jiao)合板，能在冷水中浸(jin)渍和短时(shi)间热水浸(jin)渍；

三(san)类胶(jiao)合板(ban)为耐(nai)潮(chao)胶(jiao)合板(ban)，能(neng)在冷(leng)水中短(duan)时间浸渍，适(shi)于室内常温下使用。用于家具和一般建筑用途；

四(si)类合(he)(he)板(ban)为不耐潮胶(jiao)合(he)(he)板(ban)，在室内常态下使用(yong)，一般(ban)用(yong)途胶(jiao)合(he)(he)板(ban)用(yong)材有榉木、椴(duan)木、水曲柳、桦木、榆木、杨木等。

3、对称原则：

对(dui)(dui)称(cheng)中(zhong)(zhong)心平(ping)(ping)面两(liang)侧(ce)的(de)(de)单板(ban)(ban)，无论树种，单板(ban)(ban)厚(hou)度(du)、层(ceng)数、制造方法(fa)、纤(xian)维方向和单板(ban)(ban)的(de)(de)含(han)(han)水率(lv)都应(ying)该互相对(dui)(dui)应(ying)，即对(dui)(dui)称(cheng)原则。胶(jiao)(jiao)合板(ban)(ban)中(zhong)(zhong)心平(ping)(ping)面两(liang)侧(ce)各对(dui)(dui)应(ying)层(ceng)不(bu)同(tong)方向的(de)(de)应(ying)力大小相等。因此，当胶(jiao)(jiao)合板(ban)(ban)含(han)(han)水率(lv)变化时，其结构(gou)稳定，不(bu)会(hui)产(chan)生(sheng)(sheng)变形，开(kai)裂(lie)等缺陷；反之，如(ru)果对(dui)(dui)称(cheng)中(zhong)(zhong)心平(ping)(ping)面两(liang)侧(ce)对(dui)(dui)应(ying)层(ceng)有某些差异(yi)，将会(hui)使(shi)对(dui)(dui)称(cheng)中(zhong)(zhong)心平(ping)(ping)面两(liang)侧(ce)单板(ban)(ban)的(de)(de)应(ying)力不(bu)相等，使(shi)胶(jiao)(jiao)合板(ban)(ban)产(chan)生(sheng)(sheng)变形、开(kai)裂(lie)。

4、奇数层原则：

由(you)于胶合(he)板(ban)(ban)(ban)的(de)结构是相(xiang)邻层(ceng)单板(ban)(ban)(ban)的(de)纤(xian)维方向互相(xiang)垂，又(you)必(bi)须符合(he)对称原则(ze)，因此(ci)它的(de)总(zong)层(ceng)数(shu)(shu)必(bi)定是奇数(shu)(shu)。如：三层(ceng)板(ban)(ban)(ban)、五层(ceng)板(ban)(ban)(ban)、七层(ceng)板(ban)(ban)(ban)等(deng)。奇数(shu)(shu)层(ceng)胶合(he)板(ban)(ban)(ban)弯曲时大的(de)水平(ping)(ping)剪应(ying)力作用在(zai)中心单板(ban)(ban)(ban)上(shang)，使其有(you)较大的(de)强度。偶数(shu)(shu)层(ceng)胶合(he)板(ban)(ban)(ban)弯曲时大的(de)水平(ping)(ping)剪应(ying)力作用在(zai)胶层(ceng)上(shang)而(er)不是作用在(zai)单板(ban)(ban)(ban)上(shang)，易使胶层(ceng)破(po)坏，降低了(le)胶合(he)板(ban)(ban)(ban)强度。