3D打(da)印技術是(shi)增材(cai)制(zhi)造(zao)的主要(yao)方式(shi)，依(yi)據由CAD構(gou)造(zao)的產品零件毛(mao)坯三(san)維模(mo)型，通(tong)過離散獲得堆(dui)積(ji)的路徑、限制(zhi)和(he)方式(shi)，采用堆(dui)積(ji)材(cai)料(liao)疊加(jia)起來形(xing)成三(san)維實(shi)體(ti)。對(dui)其進(jin)行分(fen)層(ceng)切片(pian)，得到(dao)各層(ceng)截面(mian)的輪廓。按(an)照(zhao)這些輪廓，激光束噴射(she)源(yuan)選(xuan)擇(ze)性地噴射(she)一層(ceng)層(ceng)所需要(yao)加(jia)工的材(cai)料(liao)粉末，并進(jin)行燒結，形(xing)成各截面(mian)并逐步(bu)疊加(jia)成三(san)維產品。
（1）建(jian)模。由CAD軟件(jian)設計出所需加工零件(jian)毛坯的(de)計算機三(san)維曲面(mian)或實(shi)體模型。
（2）分(fen)層(ceng)。將三維(wei)模型沿一(yi)定方(fang)向，離散成(cheng)一(yi)系列有序的(de)二維(wei)層(ceng)片(pian)。
（3）層面(mian)處(chu)理(li)。根據每層輪(lun)廓信息，按(an)照CAD軟件設計工藝規(gui)劃，選(xuan)擇加(jia)工參數，自(zi)動生成數控代碼。
（4）層面加工與粘(zhan)接。成形機(ji)制造一(yi)系列(lie)層片(pian)并(bing)自動將(jiang)它們聯(lian)接起來(lai)，得到三(san)維物理(li)加工的零件毛坯(pi)實體。
（5）層(ceng)層(ceng)堆積。噴(pen)射材料粉末(mo)，通過CAD軟件，按照(zhao)零件毛坯(pi)形狀進行層(ceng)層(ceng)噴(pen)射粘接(jie)。
（6）后處理(li)(li)。①清理(li)(li)零件表面，去除輔助支撐(cheng)結構。②對3D打印(yin)的鈦合金毛坯進行真空熱處理(li)(li)，消除殘余(yu)應力，提高組(zu)織(zhi)強度。
3D打(da)印具有以(yi)下特點：
（1）高度柔(rou)性，可以制(zhi)造任(ren)意復雜形狀的三維實體。
（2）CAD模(mo)型直接驅動，設計制(zhi)造高度一體化。
（3）成形過程無需專(zhuan)用夾(jia)具或工具。
（4）無需人(ren)員干預或較少干預，是(shi)一種自(zi)動化的成形過程。
（5）成形全(quan)過程的快(kuai)速性，適合現(xian)代(dai)激烈的產(chan)品市(shi)場。
如圖1所示(shi)鈦合金(jin)框架(jia)，零(ling)件外形(xing)尺寸φ148mm×44mm、壁厚4mm，加(jia)工精度要(yao)求主要(yao)針對φ36H7定位孔(kong)和(he)2個φ16g5軸承孔(kong)，其余(yu)大部(bu)分為筋。
圖1 框架零件圖
若采用(yong)鈦(tai)合金棒料(liao)加(jia)工(gong)，棒料(liao)重3.4kg，零件成(cheng)件重0.9kg，材料(liao)利用(yong)率僅為(wei)26%，大量的鈦(tai)材被(bei)掏(tao)空(kong)，并且要(yao)(yao)(yao)完成(cheng)成(cheng)件加(jia)工(gong)，需要(yao)(yao)(yao)采用(yong)數(shu)控機床(chuang)分(fen)多次進行型(xing)腔及外形的加(jia)工(gong)，工(gong)藝繁瑣。為(wei)了消除零件加(jia)工(gong)應力(li)(li)，需要(yao)(yao)(yao)采用(yong)多次熱處理去除加(jia)工(gong)應力(li)(li)，其工(gong)藝流(liu)程為(wei)：下料(liao)→粗加(jia)工(gong)→熱處理→半(ban)精加(jia)工(gong)→數(shu)控銑(xian)削內腔→熱處理→基準(zhun)加(jia)工(gong)→精加(jia)工(gong)。
若采用(yong)3D打印毛(mao)(mao)坯(pi)，毛(mao)(mao)坯(pi)質(zhi)量僅(jin)為(wei)1.2kg（見圖2）。
根據零(ling)(ling)(ling)件(jian)的(de)(de)(de)結(jie)(jie)構(gou)(gou)，通過CAD構(gou)(gou)建(jian)零(ling)(ling)(ling)件(jian)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)的(de)(de)(de)三維模(mo)型，選(xuan)擇激光(guang)燒結(jie)(jie)法(fa)，先在工(gong)(gong)(gong)(gong)(gong)(gong)(gong)作臺上鋪(pu)上一(yi)(yi)層有很好密實度和平整(zheng)度的(de)(de)(de)鈦粉，用(yong)高強(qiang)度的(de)(de)(de)激光(guang)器在上面(mian)掃描出零(ling)(ling)(ling)件(jian)截面(mian)，由點到線到面(mian)，逐漸掃描堆積，利用(yong)滾子鋪(pu)粉壓實，再燒結(jie)(jie)，形(xing)成(cheng)(cheng)一(yi)(yi)個層面(mian)，如此(ci)層層疊(die)加(jia)(jia)為一(yi)(yi)個三維實體，對有精度要求(qiu)的(de)(de)(de)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)面(mian)留余量1.5mm，一(yi)(yi)些讓(rang)位(wei)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)面(mian)及筋在3D打(da)印時(shi)直接成(cheng)(cheng)形(xing)。零(ling)(ling)(ling)件(jian)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)時(shi)，僅加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)φ36H7定位(wei)孔及端面(mian)，并采用(yong)端面(mian)壓緊方(fang)(fang)式完(wan)成(cheng)(cheng)零(ling)(ling)(ling)件(jian)2個φ16g5與軸承配合孔的(de)(de)(de)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)。零(ling)(ling)(ling)件(jian)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)夾具如圖3所(suo)示。這種(zhong)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)方(fang)(fang)法(fa)縮短(duan)了(le)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)周期，避免了(le)大余量的(de)(de)(de)切削，減少了(le)粗(cu)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)序，控制了(le)零(ling)(ling)(ling)件(jian)多次數控銑形(xing)造(zao)成(cheng)(cheng)的(de)(de)(de)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)變形(xing)，降低了(le)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)成(cheng)(cheng)本。零(ling)(ling)(ling)件(jian)加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)藝流程為：3D打(da)印→熱處(chu)(chu)理→半(ban)精加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)→熱處(chu)(chu)理→基準加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)→精加(jia)(jia)工(gong)(gong)(gong)(gong)(gong)(gong)(gong)。
經過多批次的(de)零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)加(jia)工，采用3D打印零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)毛(mao)坯(pi)具(ju)有較高(gao)(gao)的(de)柔性(xing)，無(wu)需任何(he)專(zhuan)用工具(ju)就可(ke)以(yi)快速(su)方(fang)(fang)便(bian)地制造出其(qi)毛(mao)坯(pi)，具(ju)有NC機床無(wu)法比(bi)擬的(de)優點，即快速(su)方(fang)(fang)便(bian)、高(gao)(gao)度(du)柔性(xing)。由(you)于一些尺寸是毛(mao)坯(pi)直(zhi)接成形(xing)，減少了切削次數，使(shi)零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)加(jia)工應力及變(bian)形(xing)得到(dao)(dao)了控(kong)制。該方(fang)(fang)法可(ke)以(yi)擴(kuo)展到(dao)(dao)其(qi)他大(da)型曲面零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)及高(gao)(gao)精(jing)度(du)彈(dan)體連接零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)的(de)加(jia)工，對于提高(gao)(gao)零(ling)(ling)(ling)(ling)(ling)件(jian)(jian)(jian)加(jia)工的(de)尺寸精(jing)度(du)及形(xing)位公差的(de)穩(wen)定性(xing)、降低生(sheng)產成本有著重要的(de)意(yi)義。