工程中的剪刃剪切 

　　工程(cheng)結構(gou)(gou)構(gou)(gou)件(jian)(jian)的基本變形(xing)形(xing)式(shi)之一。 定(ding)義：在(zai)(zai)一對相距很(hen)近，方向相反的橫(heng)向外力(li)作用下，構(gou)(gou)件(jian)(jian)的橫(heng)截面沿外力(li)方向發生的錯動變形(xing)。 結構(gou)(gou)和機械(xie)中(zhong)的連接件(jian)(jian)，如螺栓(shuan)、銷(xiao)釘、鍵(jian)等，在(zai)(zai)傳遞(di)力(li)時(shi)主要發生擠壓（局部(bu)(bu)承(cheng)壓）和剪(jian)切變形(xing)。對于此(ci)類直接承(cheng)受剪(jian)切的部(bu)(bu)件(jian)(jian)，在(zai)(zai)工程(cheng)計算中(zhong)常(chang)以(yi)受剪(jian)面上的剪(jian)力(li)除以(yi)其(qi)面積(ji)得出的平均剪(jian)應(ying)力(li)作為強(qiang)度計算的依據(ju)。其(qi)容許剪(jian)應(ying)力(li)則根(gen)據(ju)部(bu)(bu)件(jian)(jian)破壞(huai)時(shi)的剪(jian)應(ying)力(li)除以(yi)安全系數確定(ding) 

　　鋼材加工中的(de)剪(jian)刃剪(jian)切 

　　按(an)照被(bei)(bei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)金屬(shu)的(de)(de)(de)(de)溫度(du)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)分(fen)為(wei)(wei)(wei)(wei)熱(re)(re)(re)(re)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)和(he)(he)(he)(he)冷剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(見(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)斷(duan))。根(gen)據被(bei)(bei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)金屬(shu)的(de)(de)(de)(de)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)斷(duan)方向(xiang)分(fen)為(wei)(wei)(wei)(wei)橫剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)和(he)(he)(he)(he)縱(zong)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)。橫剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)是(shi)(shi)為(wei)(wei)(wei)(wei)了(le)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)去軋(ya)(ya)(ya)件(jian)頭尾和(he)(he)(he)(he)把軋(ya)(ya)(ya)件(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)成(cheng)要(yao)求(qiu)的(de)(de)(de)(de)長度(du)。縱(zong)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)用(yong)在(zai)(zai)鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)生產(chan)時(shi)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)去軋(ya)(ya)(ya)件(jian)的(de)(de)(de)(de)不規則側邊，或(huo)(huo)(huo)將寬帶(dai)卷(或(huo)(huo)(huo)寬板(ban)(ban)(ban)(ban))切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)成(cheng)若干個窄帶(dai)卷(或(huo)(huo)(huo)窄板(ban)(ban)(ban)(ban))。 剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)用(yong)的(de)(de)(de)(de)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)按(an)刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)的(de)(de)(de)(de)形狀和(he)(he)(he)(he)配置(zhi)以(yi)(yi)及軋(ya)(ya)(ya)件(jian)情況可(ke)分(fen)為(wei)(wei)(wei)(wei)平行刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)、斜刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)、圓(yuan)盤(pan)(pan)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)、飛(fei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)機(ji)(ji)(ji)(ji)和(he)(he)(he)(he)滾切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)。 平行刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)這(zhe)種(zhong)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)的(de)(de)(de)(de)兩片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)刃(ren)(ren)(ren)平行。(圖(tu)1a)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)時(shi)可(ke)以(yi)(yi)是(shi)(shi)下刃(ren)(ren)(ren)固(gu)定(ding)，剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)動(dong)作由上(shang)(shang)刃(ren)(ren)(ren)完(wan)成(cheng)(上(shang)(shang)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji))，也(ye)可(ke)以(yi)(yi)是(shi)(shi)上(shang)(shang)刃(ren)(ren)(ren)壓住軋(ya)(ya)(ya)件(jian)，剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)動(dong)作由下刃(ren)(ren)(ren)完(wan)成(cheng)(下切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji))。通(tong)(tong)常(chang)用(yong)于(yu)(yu)(yu)(yu)初軋(ya)(ya)(ya)坯和(he)(he)(he)(he)其他方形、矩(ju)形坯以(yi)(yi)及厚(hou)度(du)大于(yu)(yu)(yu)(yu)30～60mm扁坯的(de)(de)(de)(de)熱(re)(re)(re)(re)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)。有(you)時(shi)也(ye)用(yong)開有(you)孔槽(cao)的(de)(de)(de)(de)刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)冷剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)軋(ya)(ya)(ya)件(jian)(如(ru)管坯和(he)(he)(he)(he)小(xiao)(xiao)圓(yuan)鋼(gang)(gang)(gang)等(deng))。孔槽(cao)形狀應與被(bei)(bei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)的(de)(de)(de)(de)軋(ya)(ya)(ya)件(jian)斷(duan)面(mian)(mian)形狀相同。上(shang)(shang)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)結(jie)構(gou)簡(jian)單，但需要(yao)在(zai)(zai)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)后裝設擺(bai)(bai)動(dong)臺或(huo)(huo)(huo)擺(bai)(bai)動(dong)輥道(dao)，廣泛用(yong)于(yu)(yu)(yu)(yu)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)小(xiao)(xiao)型(xing)鋼(gang)(gang)(gang)坯或(huo)(huo)(huo)特(te)大型(xing)板(ban)(ban)(ban)(ban)坯(斷(duan)面(mian)(mian)為(wei)(wei)(wei)(wei)350mm×2400mm)。下切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)因(yin)在(zai)(zai)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)過(guo)程中上(shang)(shang)刃(ren)(ren)(ren)與下刃(ren)(ren)(ren)都運動(dong)，所以(yi)(yi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)本體結(jie)構(gou)比上(shang)(shang)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)復雜(za)，但剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)端(duan)面(mian)(mian)整齊，被(bei)(bei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)軋(ya)(ya)(ya)件(jian)端(duan)頭不易彎曲，且因(yin)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)時(shi)鋼(gang)(gang)(gang)材高于(yu)(yu)(yu)(yu)輥道(dao)面(mian)(mian)，不需在(zai)(zai)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)后設擺(bai)(bai)動(dong)升(sheng)降輥道(dao)。 斜刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji) 斜刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)的(de)(de)(de)(de)一(yi)(yi)(yi)個刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)與另一(yi)(yi)(yi)個刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)成(cheng)一(yi)(yi)(yi)定(ding)角度(du)。(圖(tu)1b)一(yi)(yi)(yi)般(ban)上(shang)(shang)刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)傾(qing)斜，傾(qing)斜角為(wei)(wei)(wei)(wei)1.5o～6o，剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)厚(hou)板(ban)(ban)(ban)(ban)時(shi)為(wei)(wei)(wei)(wei)8o～12o，下刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)水(shui)平。這(zhe)類剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)機(ji)(ji)(ji)(ji)由于(yu)(yu)(yu)(yu)刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)與軋(ya)(ya)(ya)件(jian)接觸面(mian)(mian)積小(xiao)(xiao)和(he)(he)(he)(he)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)力小(xiao)(xiao)，常(chang)用(yong)于(yu)(yu)(yu)(yu)冷剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)或(huo)(huo)(huo)熱(re)(re)(re)(re)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)、帶(dai)鋼(gang)(gang)(gang)、薄板(ban)(ban)(ban)(ban)坯及焊管坯等(deng)，也(ye)用(yong)于(yu)(yu)(yu)(yu)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)成(cheng)束的(de)(de)(de)(de)小(xiao)(xiao)型(xing)鋼(gang)(gang)(gang)材。斜刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)也(ye)有(you)上(shang)(shang)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)和(he)(he)(he)(he)下切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)之分(fen)。近年來液壓傳動(dong)的(de)(de)(de)(de)下切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)式(shi)(shi)(shi)斜刃(ren)(ren)(ren)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)得到(dao)較廣泛的(de)(de)(de)(de)使用(yong)。這(zhe)種(zhong)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)有(you)結(jie)構(gou)簡(jian)單、緊(jin)(jin)湊、重(zhong)量輕、剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)平穩、能自動(dong)防止(zhi)過(guo)載等(deng)優點，但生產(chan)率(lv)低(di)，要(yao)求(qiu)電機(ji)(ji)(ji)(ji)功(gong)率(lv)大。 圓(yuan)盤(pan)(pan)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji) 兩個刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)做成(cheng)圓(yuan)盤(pan)(pan)狀，用(yong)于(yu)(yu)(yu)(yu)鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)及帶(dai)鋼(gang)(gang)(gang)邊部的(de)(de)(de)(de)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)；將鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)或(huo)(huo)(huo)帶(dai)鋼(gang)(gang)(gang)縱(zong)向(xiang)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)成(cheng)窄條時(shi)采用(yong)多對(dui)刀(dao)(dao)(dao)片(pian)(pian)(pian)(pian)(pian)。圓(yuan)盤(pan)(pan)式(shi)(shi)(shi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)一(yi)(yi)(yi)般(ban)都布(bu)置(zhi)在(zai)(zai)鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)精整線上(shang)(shang)或(huo)(huo)(huo)冷、熱(re)(re)(re)(re)帶(dai)鋼(gang)(gang)(gang)的(de)(de)(de)(de)縱(zong)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)機(ji)(ji)(ji)(ji)組(zu)作業線上(shang)(shang)。被(bei)(bei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)板(ban)(ban)(ban)(ban)帶(dai)鋼(gang)(gang)(gang)的(de)(de)(de)(de)厚(hou)度(du)通(tong)(tong)常(chang)小(xiao)(xiao)于(yu)(yu)(yu)(yu)20～40mm。為(wei)(wei)(wei)(wei)了(le)擴大剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)厚(hou)度(du)范圍(wei)，有(you)的(de)(de)(de)(de)國家采用(yong)兩臺串聯布(bu)置(zhi)的(de)(de)(de)(de)圓(yuan)盤(pan)(pan)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)以(yi)(yi)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)厚(hou)度(du)38mm左右的(de)(de)(de)(de)鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)。第(di)一(yi)(yi)(yi)臺圓(yuan)盤(pan)(pan)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)入板(ban)(ban)(ban)(ban)厚(hou)的(de)(de)(de)(de)5%～10%，緊(jin)(jin)接著第(di)二臺圓(yuan)盤(pan)(pan)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)將鋼(gang)(gang)(gang)板(ban)(ban)(ban)(ban)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)斷(duan)。 飛(fei)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)機(ji)(ji)(ji)(ji) 用(yong)于(yu)(yu)(yu)(yu)橫向(xiang)剪(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)(jian)切(qie)(qie)(qie)(qie)(qie)(qie)(qie)(qie)運動(dong)中的(de)(de)(de)(de)軋(ya)(ya)(ya)件(jian)。

剪刃分類 

　　熱軋剪刃、冷剪剪刃、軋鋼剪刃、飛剪剪刃、冶金刀片、中厚板剪刃、型棒材剪刃、圓盤剪刃、連軋機剪刃、飛剪刀片，定尺剪刃，凹凸剪刃，平剪刃，剪板機剪刃，上剪刃，下剪刃 。