在(zai)煤礦(kuang)鉆井中，牙(ya)輪鉆頭(tou)能適(shi)應(ying)各種地(di)層的(de)(de)(de)鉆井，是(shi)主要的(de)(de)(de)破(po)巖工(gong)具之一。牙(ya)輪鉆頭(tou)在(zai)礦(kuang)井工(gong)作時(shi)的(de)(de)(de)運動狀態和受力狀態是(shi)相當復雜的(de)(de)(de)。國(guo)內外對牙(ya)輪鉆頭(tou)的(de)(de)(de)工(gong)作原理,論研究(jiu)或實驗研究(jiu)方面都作了(le)大量的(de)(de)(de)工(gong)作，這些研究(jiu)成果為鉆頭(tou)的(de)(de)(de)設計使用提供了(le)依據。

三牙(ya)輪鉆(zhan)頭在礦井的運(yun)動，決定牙(ya)輪與(yu)牙(ya)齒的運(yun)動，也就直接(jie)決定牙(ya)齒對地層(ceng)巖石的破碎作(zuo)用。因此，在了(le)解(jie)鉆(zhan)頭破碎巖石的工作(zuo)原理之前，首先應(ying)了(le)解(jie)鉆(zhan)頭在礦井的運(yun)動。

1.鉆頭的公轉

鉆(zhan)(zhan)頭牙輪繞(rao)(rao)鉆(zhan)(zhan)頭軸線(xian)(xian)作順時針(zhen)方向旋轉(zhuan)(zhuan)(zhuan)的(de)(de)運動(dong)簡(jian)稱為鉆(zhan)(zhan)頭的(de)(de)公(gong)(gong)轉(zhuan)(zhuan)(zhuan)。鉆(zhan)(zhan)頭公(gong)(gong)轉(zhuan)(zhuan)(zhuan)的(de)(de)速度(du)就是轉(zhuan)(zhuan)(zhuan)盤或井下動(dong)力鉆(zhan)(zhan)具的(de)(de)旋轉(zhuan)(zhuan)(zhuan)速度(du)。鉆(zhan)(zhan)頭公(gong)(gong)轉(zhuan)(zhuan)(zhuan)時，牙輪繞(rao)(rao)鉆(zhan)(zhan)頭軸線(xian)(xian)旋轉(zhuan)(zhuan)(zhuan)，牙輪上各(ge)排(pai)牙齒(chi)繞(rao)(rao)鉆(zhan)(zhan)頭軸線(xian)(xian)旋轉(zhuan)(zhuan)(zhuan)的(de)(de)線(xian)(xian)速度(du)不同，外(wai)排(pai)齒(chi)的(de)(de)線(xian)(xian)速度(du)最(zui)大。

2.鉆頭的自轉

鉆(zhan)頭旋(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)時，沿(yan)著(zhu)從(cong)牙(ya)輪(lun)(lun)(lun)底平面(mian)(mian)到(dao)牙(ya)輪(lun)(lun)(lun)尖部(bu)的方(fang)向看，牙(ya)輪(lun)(lun)(lun)繞自身的軸線(xian)作(zuo)反(fan)時針方(fang)向的旋(xuan)轉(zhuan)(zhuan)(zhuan)(zhuan)稱(cheng)自轉(zhuan)(zhuan)(zhuan)(zhuan)。牙(ya)輪(lun)(lun)(lun)的轉(zhuan)(zhuan)(zhuan)(zhuan)動是巖(yan)石對牙(ya)齒的吃入破碎作(zuo)用(yong)產生反(fan)作(zuo)用(yong)的結(jie)果。牙(ya)輪(lun)(lun)(lun)自轉(zhuan)(zhuan)(zhuan)(zhuan)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)的影響因(yin)素有公(gong)轉(zhuan)(zhuan)(zhuan)(zhuan)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)、鉆(zhan)頭結(jie)構、齒面(mian)(mian)結(jie)構、鉆(zhan)井參(can)數和巖(yan)石性質等。一般(ban)情況下(xia)，牙(ya)輪(lun)(lun)(lun)自轉(zhuan)(zhuan)(zhuan)(zhuan)的轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)比鉆(zhan)頭公(gong)轉(zhuan)(zhuan)(zhuan)(zhuan)的轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)快。把(ba)牙(ya)輪(lun)(lun)(lun)自轉(zhuan)(zhuan)(zhuan)(zhuan)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)與鉆(zhan)頭公(gong)轉(zhuan)(zhuan)(zhuan)(zhuan)轉(zhuan)(zhuan)(zhuan)(zhuan)速(su)(su)之比稱(cheng)為輪(lun)(lun)(lun)頭比，輪(lun)(lun)(lun)頭比的值一般(ban)在1-1.5之間。

3.鉆(zhan)頭的縱(zong)振(軸向(xiang)振動)

鉆(zhan)頭(tou)(tou)(tou)工作時(shi)，對一(yi)個牙(ya)輪(lun)(lun)(lun)而言，牙(ya)齒(chi)(chi)(chi)(chi)與(yu)井(jing)底的(de)接觸是(shi)單(dan)齒(chi)(chi)(chi)(chi)、雙齒(chi)(chi)(chi)(chi)交替進行的(de)。單(dan)齒(chi)(chi)(chi)(chi)著地(di)時(shi)，牙(ya)輪(lun)(lun)(lun)的(de)輪(lun)(lun)(lun)心處于最高位置，雙齒(chi)(chi)(chi)(chi)著地(di)時(shi)那么輪(lun)(lun)(lun)心下(xia)(xia)降。牙(ya)輪(lun)(lun)(lun)在(zai)轉(zhuan)(zhuan)動(dong)過(guo)程(cheng)中，輪(lun)(lun)(lun)心位置不(bu)斷上(shang)下(xia)(xia)變換，使鉆(zhan)頭(tou)(tou)(tou)沿軸(zhou)向(xiang)作上(shang)下(xia)(xia)往(wang)復運動(dong)，這(zhe)就是(shi)鉆(zhan)頭(tou)(tou)(tou)的(de)軸(zhou)向(xiang)振(zhen)(zhen)動(dong)。縱振(zhen)(zhen)振(zhen)(zhen)幅就是(shi)輪(lun)(lun)(lun)心的(de)垂直位移，它與(yu)牙(ya)齒(chi)(chi)(chi)(chi)的(de)齒(chi)(chi)(chi)(chi)高、齒(chi)(chi)(chi)(chi)距等鉆(zhan)頭(tou)(tou)(tou)結構參數(shu)及(ji)巖性有關。在(zai)軟地(di)層，牙(ya)齒(chi)(chi)(chi)(chi)吃入(ru)深(shen)、振(zhen)(zhen)幅小，硬地(di)層那么振(zhen)(zhen)動(dong)加劇(ju)。振(zhen)(zhen)動(dong)的(de)頻率(lv)與(yu)牙(ya)輪(lun)(lun)(lun)齒(chi)(chi)(chi)(chi)數(shu)及(ji)牙(ya)輪(lun)(lun)(lun)轉(zhuan)(zhuan)速成正(zheng)比。在(zai)旋轉(zhuan)(zhuan)鉆(zhan)井(jing)中，鉆(zhan)頭(tou)(tou)(tou)縱振(zhen)(zhen)頻率(lv)一(yi)般為100一(yi)500次/min。

止匕外，由于(yu)井底不(bu)平，鉆(zhan)頭(tou)產生振(zhen)(zhen)幅較(jiao)大的(de)(de)低頻(pin)振(zhen)(zhen)動(dong)。據(ju)國外資(zi)料介紹，低頻(pin)振(zhen)(zhen)動(dong)的(de)(de)振(zhen)(zhen)幅就(jiu)是(shi)井底凹凸局部的(de)(de)高(gao)差,一般為10mm左右，頻(pin)率(lv)(lv)低于(yu)50次/min。低頻(pin)縱(zong)振(zhen)(zhen)對(dui)鉆(zhan)頭(tou)是(shi)不(bu)利的(de)(de)因素，在硬(ying)地層中(zhong)會造成(cheng)跳鉆(zhan)。牙(ya)輪鉆(zhan)頭(tou)的(de)(de)縱(zong)振(zhen)(zhen)是(shi)上(shang)述兩種振(zhen)(zhen)動(dong)之和，它構成(cheng)了牙(ya)齒的(de)(de)沖擊壓(ya)入作用，破碎巖石，提(ti)高(gao)破碎效率(lv)(lv)。

4.橫向振動

所謂橫向振(zhen)(zhen)動(dong)(dong)，就是沿著垂(chui)直于鉆(zhan)(zhan)頭軸線方向的(de)(de)振(zhen)(zhen)動(dong)(dong)。造(zao)成鉆(zhan)(zhan)頭橫向振(zhen)(zhen)動(dong)(dong)的(de)(de)因素很多，包括鉆(zhan)(zhan)頭與巖石互作用(yong)、鉆(zhan)(zhan)柱的(de)(de)彎曲變形(xing)，鉆(zhan)(zhan)柱的(de)(de)偏心旋轉，鉆(zhan)(zhan)柱質(zhi)量分布(bu)不均勻、地層傾角以及(ji)井底巖石性質(zhi)差異等等。鉆(zhan)(zhan)頭的(de)(de)橫向振(zhen)(zhen)動(dong)(dong)對鉆(zhan)(zhan)柱的(de)(de)橫向振(zhen)(zhen)動(dong)(dong)有直接的(de)(de)影響，也(ye)是造(zao)成鉆(zhan)(zhan)頭失(shi)效的(de)(de)重要原因。

5.扭轉振動

鉆頭(tou)的(de)周期(qi)(qi)性運(yun)動(dong)(dong)(dong)導致扭矩成(cheng)周期(qi)(qi)性變(bian)化，引(yin)起鉆頭(tou)周期(qi)(qi)性的(de)扭轉振動(dong)(dong)(dong)。鉆頭(tou)的(de)扭轉振動(dong)(dong)(dong)主(zhu)要由鉆頭(tou)的(de)粘滑運(yun)動(dong)(dong)(dong)造成(cheng)的(de)，即鉆頭(tou)旋轉速(su)(su)度變(bian)化很大,在某一瞬時(shi)鉆頭(tou)可能靜(jing)止不(bu)動(dong)(dong)(dong)，過一段時(shi)間后(hou)便以數倍于平均轉速(su)(su)的(de)速(su)(su)度旋轉，這樣就會(hui)引(yin)起鉆頭(tou)的(de)失效，也可能引(yin)起鉆柱的(de)早期(qi)(qi)疲勞破壞。因此應盡量防止鉆頭(tou)出現這種現象。

6,牙輪的滑動

破碎(sui)不(bu)同(tong)(tong)(tong)類型巖石，對鉆(zhan)頭(tou)要(yao)求不(bu)同(tong)(tong)(tong)的(de)滑(hua)(hua)(hua)動(dong)(dong)(dong)量(liang)，可(ke)通過設計(ji)鉆(zhan)頭(tou)時采用(yong)不(bu)同(tong)(tong)(tong)的(de)結(jie)構(gou)及(ji)參(can)數獲(huo)得。對于一個(ge)(ge)牙(ya)(ya)(ya)(ya)輪而言，不(bu)同(tong)(tong)(tong)位置的(de)齒(chi)(chi)(chi)(chi)排(pai)的(de)滑(hua)(hua)(hua)動(dong)(dong)(dong)方向(xiang)是(shi)(shi)不(bu)同(tong)(tong)(tong)的(de)。外(wai)排(pai)齒(chi)(chi)(chi)(chi)及(ji)靠近外(wai)排(pai)齒(chi)(chi)(chi)(chi)的(de)齒(chi)(chi)(chi)(chi)排(pai)，一般(ban)(ban)是(shi)(shi)正向(xiang)滑(hua)(hua)(hua)動(dong)(dong)(dong)(假設鉆(zhan)頭(tou)旋(xuan)轉,而牙(ya)(ya)(ya)(ya)輪不(bu)自轉時，牙(ya)(ya)(ya)(ya)齒(chi)(chi)(chi)(chi)在(zai)(zai)井底的(de)滑(hua)(hua)(hua)動(dong)(dong)(dong)就是(shi)(shi)正向(xiang)滑(hua)(hua)(hua)動(dong)(dong)(dong)):牙(ya)(ya)(ya)(ya)輪尖(jian)部的(de)齒(chi)(chi)(chi)(chi)排(pai)及(ji)靠近牙(ya)(ya)(ya)(ya)輪尖(jian)部的(de)齒(chi)(chi)(chi)(chi)排(pai)一般(ban)(ban)是(shi)(shi)負向(xiang)滑(hua)(hua)(hua)動(dong)(dong)(dong);而在(zai)(zai)外(wai)排(pai)齒(chi)(chi)(chi)(chi)與(yu)尖(jian)部齒(chi)(chi)(chi)(chi)排(pai)之(zhi)間(jian)的(de)某(mou)個(ge)(ge)中間(jian)齒(chi)(chi)(chi)(chi)排(pai)或(huo)虛擬齒(chi)(chi)(chi)(chi)排(pai)做純(chun)滾動(dong)(dong)(dong)o一般(ban)(ban)情(qing)況(kuang)下(xia)(xia)，軟地(di)層(ceng)鉆(zhan)頭(tou)應具有(you)較大的(de)滑(hua)(hua)(hua)動(dong)(dong)(dong)量(liang)，硬地(di)層(ceng)鉆(zhan)頭(tou)應盡量(liang)減少或(huo)不(bu)產生滑(hua)(hua)(hua)動(dong)(dong)(dong)，防止牙(ya)(ya)(ya)(ya)齒(chi)(chi)(chi)(chi)早(zao)期損壞(huai)。但是(shi)(shi)，由于鉆(zhan)頭(tou)工作(zuo)(zuo)時，牙(ya)(ya)(ya)(ya)輪與(yu)牙(ya)(ya)(ya)(ya)掌軸(zhou)頸的(de)相對運(yun)(yun)動(dong)(dong)(dong)總是(shi)(shi)存在(zai)(zai)摩擦(ca)阻(zu)力等原因，即使設計(ji)的(de)是(shi)(shi)純(chun)滾動(dong)(dong)(dong)鉆(zhan)頭(tou),實(shi)際(ji)鉆(zhan)進(jin)中仍然存在(zai)(zai)著滑(hua)(hua)(hua)動(dong)(dong)(dong)。對純(chun)滾動(dong)(dong)(dong)鉆(zhan)頭(tou)作(zuo)(zuo)室內模擬試驗，發(fa)現約有(you)20%的(de)滑(hua)(hua)(hua)動(dong)(dong)(dong)量(liang)。上述幾種(zhong)運(yun)(yun)動(dong)(dong)(dong)是(shi)(shi)牙(ya)(ya)(ya)(ya)輪鉆(zhan)頭(tou)在(zai)(zai)井下(xia)(xia)工作(zuo)(zuo)時同(tong)(tong)(tong)時發(fa)生的(de)復合(he)運(yun)(yun)動(dong)(dong)(dong)。實(shi)際(ji)鉆(zhan)進(jin)時，還有(you)整個(ge)(ge)鉆(zhan)頭(tou)的(de)向(xiang)下(xia)(xia)運(yun)(yun)動(dong)(dong)(dong)，其(qi)向(xiang)下(xia)(xia)運(yun)(yun)動(dong)(dong)(dong)的(de)速(su)度(du)就是(shi)(shi)鉆(zhan)頭(tou)鉆(zhan)進(jin)的(de)機械鉆(zhan)速(su)。