曲柄板課程設(shè)計(jì)

摘要機(jī)械產(chǎn)品的生產(chǎn)過(guò)程是從原材料開(kāi)始到成品出廠的全部勞動(dòng)過(guò)程。它包括了毛坯的制造，零件的機(jī)械加工和熱處理，機(jī)器的裝配、檢驗(yàn)、測(cè)試、和涂裝等過(guò)程。機(jī)械加工工藝是實(shí)現(xiàn)產(chǎn)品設(shè)計(jì)，保證產(chǎn)品質(zhì)量，節(jié)約能源，降低消耗的重要手段，是生產(chǎn)中最活潑的因素。它既是構(gòu)思和想法，又是實(shí)在的方法和手段，并落實(shí)在由工件、機(jī)床、夾具所構(gòu)成的工藝系統(tǒng)中。在制定工藝過(guò)程中，要確定各工序的安裝工位和該工序需要的工步，加工該工序所需的機(jī)床，進(jìn)給量，切削深度，主軸轉(zhuǎn)速和切削速度，該工序的夾具，刀具及量具，還有走刀次數(shù)和走刀長(zhǎng)度，最后計(jì)算該工序的根本時(shí)間，輔助時(shí)間和工作地效勞時(shí)間。夾具是機(jī)床上裝夾工件的一種裝置，使工件相對(duì)于機(jī)床和刀具有一個(gè)正確的位置，并在加工過(guò)程中保持該位置不變。在使用夾具裝夾工件時(shí)，工件相對(duì)于刀具及機(jī)床的位置精度由夾具保證，不受工人技術(shù)水平的影響，使一批工件的加工精度趨于一致。使用夾具裝夾工件方便、快速，工件不需要?jiǎng)澗€找正，可顯著地減少輔助工時(shí)，工件在夾具中裝夾后提高了工件的剛性，可加大切削用量；可使用多件、多工位裝夾工件的夾具，并可采用高效夾緊機(jī)構(gòu)，進(jìn)一步提高勞動(dòng)生產(chǎn)率。關(guān)鍵詞：工藝，工序，工步，加工余量，定位方案，夾緊力AbstractMechanicalproductionprocessfromrawmaterialtofinishedproductallthelaborprocess.Itincludesablankmanufacturing,partsmachiningandheattreatment,machineassembly,inspection,testing,andpaintingandotherprocesses.Processisthemostactivefactorofproduction.Machiningprocessistoachieveproductdesign,productquality,saveenergyandreduceconsumptionoftheimportantmeansisthemostactivefactorofproduction.Itisbothaconceptandideas,butalsorealwaysandmeans,andtoimplementintheworkpiece,machinetools,fixturesposedbytheprocesssystem.Inthedevelopmentprocess,wemustdeterminetheinstallationprocessstationandtheprocessneedsfurtherwork,processingoftheprocessoflocomotivesandmachinetools,feedrate,cuttingdepth,spindlespeedandcuttingspeed,theprocessofthefixture,toolandgauge,therearethecuttingtimesandtoolpathlength,thefinalcalculationofthebasictimeoftheprocess,supporttimeandefforttoservice.Machinetoolclampingfixtureisadevicetotheworkpiecerelativetothemachinetoolandcuttingtoolworkpiecehaveacorrectposition,andduringprocessingtomaintainthesameposition.Usingthefixtureworkpiececlampingoftheworkpiecerelativetothelocationofmachinetoolsandprecisionguaranteedbythefixture,withouttechnicalskills,whichmakesthenumberofworkpiecemachiningprecisionofline．Workpiececlampingfixtureeasytouse,fast,crossedtheworkpiecedoesnotneedtofindis,cansignificantlyreducetheauxiliaryworkinghours,afterclampingtheworkpieceinthefixturetoimprovetherigidityoftheworkpiececanbeincreasedcutting;canusemultiplepieces,multiplebitworkpiececlampingfixture,clampingbodiescanbeusedefficientlytofurtherimprovelaborproductivityKeywords：Technology,theprocess,processstep,allowances，clampingforce目錄TOC\o"1-2"\h\u13169摘要 ②適用范圍螺旋夾緊機(jī)構(gòu)結(jié)構(gòu)簡(jiǎn)單,制造方便夾緊行程不受限制且?jiàn)A緊可靠，所以在手動(dòng)夾緊裝置中廣泛使用。偏心夾緊機(jī)構(gòu)偏心夾緊機(jī)構(gòu)是指用偏心件直接或間接與其他原件組合來(lái)使用的實(shí)心夾緊工件的機(jī)構(gòu)。適用范圍：圓偏心輪夾緊后，自鎖性能較差，只適用于切削力負(fù)荷較小又無(wú)很大振動(dòng)的場(chǎng)合，又因結(jié)構(gòu)尺寸不能太大，為滿(mǎn)足自鎖條件，夾緊行程受到限制，所以對(duì)夾緊面的尺寸公差要求嚴(yán)格?！?〕鉸鏈夾緊機(jī)構(gòu)鉸鏈夾緊機(jī)構(gòu)是由鉸鏈杠桿組合而成的一種增力結(jié)構(gòu)，其結(jié)構(gòu)簡(jiǎn)單，增力倍數(shù)大，摩擦損失小，但無(wú)自鎖性能。常與動(dòng)力裝置連用，故在機(jī)械化裝置中廣泛應(yīng)用?！?〕聯(lián)動(dòng)夾緊機(jī)構(gòu)利用一個(gè)原始作用力實(shí)現(xiàn)多件或單件的多點(diǎn)多向同時(shí)夾緊的機(jī)構(gòu)稱(chēng)為聯(lián)動(dòng)夾緊機(jī)構(gòu)。定心夾緊機(jī)構(gòu)定心夾緊機(jī)構(gòu)是一種能夠同時(shí)實(shí)現(xiàn)定位和夾緊的特殊夾緊機(jī)構(gòu)。它的定位原件也是夾緊原件，它將工件定位并夾緊以后，能使其定位面的中心或?qū)ΨQ(chēng)中心固定在規(guī)定的位置。定心夾緊機(jī)構(gòu)可以分為剛性定心夾緊機(jī)構(gòu)和彈性定心夾緊機(jī)構(gòu)。剛性定心夾緊機(jī)構(gòu)定心精度不高，但夾緊行程大，常用在粗加工，彈性定心夾緊機(jī)構(gòu)定位精度高，但夾緊行程小，常用與精加工。分度裝置分度裝置常用在銑床或鉆床的轉(zhuǎn)開(kāi)工作臺(tái)或其它必須分度的裝置上。分度裝置一般由對(duì)定銷(xiāo)和分度盤(pán)兩個(gè)主要局部組成。其中之一需要裝在夾具需要分度轉(zhuǎn)動(dòng)的部位上，另一個(gè)裝在夾具需要固定的部位上。設(shè)計(jì)分度時(shí)最主要的原那么是：〔1〕保證必要的分度精度，產(chǎn)生分度誤差的原因很多，主要原因是分度盤(pán)與分度銷(xiāo)之間存在間隙，分度銷(xiāo)與固定套之間的間隙，分度套筒在分度盤(pán)上的位置不夠精確，以及分度套內(nèi)外兩圓柱之間的偏心差?！?〕保證分度的方便可靠，加工批量較大的工件時(shí)，常用機(jī)械化自動(dòng)化的分度，批量較小時(shí)常用手動(dòng)分度。〔3〕保證分度銷(xiāo)強(qiáng)度足夠強(qiáng)，為保證分度銷(xiāo)足夠強(qiáng)強(qiáng)度，在受力較大的情況下，往往使分度銷(xiāo)只起分度作用，而防止承受任何外力。分度裝置可分為回轉(zhuǎn)分度裝置和直線分度裝置。回轉(zhuǎn)分度裝置，是指在工件一次裝夾中通過(guò)夾具的某局部帶開(kāi)工作轉(zhuǎn)動(dòng)一定的角度，完成多工位加工的分度裝置?；剞D(zhuǎn)分度裝置主要用于工件外表圓周分度孔或槽的加工。直線分度裝置是指工件一次裝夾中，通過(guò)夾具的某局部帶開(kāi)工件直線移動(dòng)一定距離完成多工位加工的分度裝置，它是對(duì)直線方向上的尺寸進(jìn)行分度的裝置。夾具體夾具體是夾具的根底件，他將夾具上的各種裝置和原件連接成一個(gè)整體，并通過(guò)它將夾具安裝到機(jī)床上。它的結(jié)構(gòu)形狀尺寸及大小，取決于加工工件的特點(diǎn)尺寸大小，各種原件的結(jié)構(gòu)和布局，夾具機(jī)床的連接方式，切削力及重力等大小的影響。1.夾具毛坯的類(lèi)型〔1〕鑄造夾具體鑄造夾具體工藝性好，可鑄成各種復(fù)雜形體。它具有較好的抗壓強(qiáng)度，剛度和抗震性，切削性好，但生產(chǎn)周期長(zhǎng)，需時(shí)效處理，以消除內(nèi)應(yīng)力。常用材料灰鑄鐵，要求強(qiáng)度高時(shí)用鑄鋼，要求重量輕時(shí)用鑄鋁。目前鑄造夾具體的應(yīng)用最廣?！?〕焊接夾具體焊接夾具體是采用鋼板型材焊接而成，這類(lèi)結(jié)構(gòu)制造方便，生產(chǎn)周期短，本錢(qián)低。易減輕重量。但焊接過(guò)程中的熱變形和剩余應(yīng)力較大，易變形，為此，焊接后須進(jìn)行退火處理，以保證夾具尺寸的穩(wěn)定性。它適用于新產(chǎn)品適制，臨時(shí)急用及結(jié)構(gòu)簡(jiǎn)單的夾具體?！?〕鍛造夾具體鍛造夾具體適用于結(jié)構(gòu)簡(jiǎn)單，尺寸不大，要求強(qiáng)度和剛度較大的夾具體。它能承受較大的沖擊載荷，鍛造后酌情采用調(diào)質(zhì)，正火或回火處理?！?〕裝配夾具體裝配夾具體是選用標(biāo)準(zhǔn)毛胚件或零件及個(gè)別非標(biāo)準(zhǔn)件通過(guò)銷(xiāo)釘，螺釘連接組裝而成。為保證夾具體不會(huì)產(chǎn)生不允許的變形或振動(dòng)，夾具體應(yīng)有足夠的強(qiáng)度或剛度。2.夾具體應(yīng)滿(mǎn)足的要求〔1〕應(yīng)有足夠的強(qiáng)度和剛度。在加工過(guò)程中，夾具體要承受較大的切削力和夾緊力。為保證夾具體不會(huì)產(chǎn)生不允許的變形或振動(dòng)，夾具體應(yīng)有足夠的驅(qū)動(dòng)和剛度?！?)力求結(jié)構(gòu)簡(jiǎn)單和裝卸方便。在保證強(qiáng)度和剛度的前提下。盡可能體積小重量輕?！?)結(jié)構(gòu)工藝性好，夾具體應(yīng)便于制造、裝配、檢驗(yàn)和維修。例如：鑄造夾具體上安裝各種元件的外表應(yīng)鑄造出3—5mm凸臺(tái)。〔4)排除，切屑要方便。〔5〕夾具體在機(jī)床上安裝穩(wěn)定可靠?！?〕有適當(dāng)?shù)木群统叽绶€(wěn)定性。夾具體上的重要外表，如安裝定位元件的外表，夾具體的安裝基面，應(yīng)有適當(dāng)?shù)某叽绾托螤罹龋鼈冎g還應(yīng)有適當(dāng)?shù)奈恢镁取?.2專(zhuān)用夾具的設(shè)計(jì)及原理分析為保證曲柄板使用要求，需加工曲柄板上五個(gè)的孔和同軸線上五個(gè)的沉孔且相互夾角從而設(shè)計(jì)立軸回轉(zhuǎn)分度夾具，保證工件的加工精度和加工質(zhì)量。定位基準(zhǔn)和定位元件的設(shè)計(jì)與分析根據(jù)曲柄板的形狀和加工技術(shù)要求及精度。工件定位用了平面定位，內(nèi)孔定位及外圓柱定位。當(dāng)曲柄板底面與設(shè)置成三角形布置的三個(gè)固定支撐接觸為平面定位，限制工件的,,三個(gè)自由度，工件H8孔與分度盤(pán)上H7的外圓柱面接觸行成圓柱孔定位，限制了工件,兩個(gè)自由度，當(dāng)工件上h6外圓柱面與活動(dòng)V形塊接觸形成外圓柱定位，限制了一個(gè)自由度。如圖3-1所示:圖3-1曲柄板定位示意圖綜上分析：H8孔，端面和h6外圓在分度盤(pán)f7外圓，三個(gè)支撐釘和工件以活動(dòng)V形塊上定位，限制了工件的6個(gè)自由度，實(shí)現(xiàn)了曲柄板的完全定位。分度裝置的設(shè)計(jì)與分析根據(jù)要求要在立式鉆床上加工曲柄板上通孔5—mm和同軸線上沉孔5mm深3.5mm，且相互夾角均勻分布由可知，為滿(mǎn)足加工要求應(yīng)選用回轉(zhuǎn)分度裝置，切選用軸向分度形式。即對(duì)定銷(xiāo)的運(yùn)動(dòng)方向與分度盤(pán)的回轉(zhuǎn)軸線平行。在軸向分度形式中最常用的對(duì)定機(jī)構(gòu)。其特點(diǎn)是結(jié)構(gòu)簡(jiǎn)單，制造容易，當(dāng)對(duì)定機(jī)構(gòu)有污物或碎屑粘付時(shí)對(duì)定銷(xiāo)插入分度套時(shí)能將污物推出，并不影響對(duì)定元件的接觸。主要用于中等精度分度的裝置中。對(duì)定銷(xiāo)與分度套之間常采用H7/g6的配合。其結(jié)構(gòu)如以下圖：1—手柄2—夾具體3—分度盤(pán)4—分度盤(pán)套筒5—對(duì)定銷(xiāo)6—彈簧圖3—2槍栓式圓柱銷(xiāo)對(duì)定機(jī)構(gòu)分度原理分析：對(duì)定銷(xiāo)5裝在夾具體2上，并借助彈簧的作用插入分度盤(pán)相應(yīng)的孔中，以確定工件與鉆套間的相對(duì)位置。分度盤(pán)的孔座數(shù)與工件被加工孔數(shù)相等，且成4X=均勻分布。分度時(shí)抬起手柄1拔出對(duì)定銷(xiāo)5，轉(zhuǎn)動(dòng)分度盤(pán)3，當(dāng)下一個(gè)分度孔與對(duì)定銷(xiāo)對(duì)準(zhǔn)時(shí)，對(duì)定銷(xiāo)在彈簧作用下，插入分度孔即可鉆第二個(gè)孔，以此類(lèi)推。鉆模板與導(dǎo)引元件的設(shè)計(jì)鉆模板的設(shè)計(jì)鉆模板是供安裝鉆套用的。要求具有一定的強(qiáng)度和剛度，以防止由于變形而影響鉆套的位置精度和導(dǎo)向精度。常用的有以下幾種類(lèi)型：〔1〕固定式鉆模板這種鉆模版是直接固定在夾具體上而不能移動(dòng)的，因此用固定式鉆模版加工孔時(shí)所獲得較高的位置精度，但有時(shí)對(duì)裝卸工件不甚方便?！?〕鉸鏈?zhǔn)姐@模板鉆模板與夾具體為鉸鏈連接，使用鉸鏈?zhǔn)姐@模板裝卸工件方便，但鉸鏈處必然有間隙，因而加工孔的位置精度比固定式鉆模板的精度低。〔3〕可卸式鉆模板當(dāng)裝卸工件必須將鉆模板取下時(shí)，那么采用可卸式鉆模板，使用這種鉆模板時(shí)，裝卸鉆模板較費(fèi)時(shí)費(fèi)力，鉆模的位置精度較低，一般多在使用其它類(lèi)型鉆模板不便于裝夾工件時(shí)使用。〔4〕懸掛式鉆模板在立式鉆床上多用多軸轉(zhuǎn)動(dòng)頭加工平行孔系時(shí)，所用鉆模板常通過(guò)兩導(dǎo)柱直接懸掛在傳動(dòng)箱上，并隨機(jī)床主軸往復(fù)移動(dòng)，這種鉆模版為懸掛式鉆模板。根據(jù)曲柄板幾何形狀尺寸，加工特點(diǎn)及定位基準(zhǔn)，為方便裝卸工件應(yīng)選用鉸鏈?zhǔn)姐@模板。2.導(dǎo)引元件設(shè)計(jì)鉆套在鉆模中的作用是保證被加工孔的位置精度，引導(dǎo)刀具防止其在加工過(guò)程中發(fā)生偏斜，提高刀具的剛性，防止加工時(shí)的振動(dòng)。常用的標(biāo)準(zhǔn)鉆模有以下幾種類(lèi)型：〔1〕固定鉆套固定鉆套安裝在鉆模板或夾具體中，其配合為H7/h6或H7/r6。固定鉆套結(jié)構(gòu)簡(jiǎn)單，鉆孔精度高，適用于單一鉆孔工序和小批量生產(chǎn)?！?〕可換鉆套當(dāng)工件為單一鉆孔工藝，大批量生產(chǎn)時(shí)為便于更換磨損的鉆套，選用可換鉆套。〔3〕快換鉆套當(dāng)工件需鉆，擴(kuò)，鉸多工藝加工時(shí)，能快速更換不同孔徑的鉆套，應(yīng)選用快換鉆套。更換鉆套時(shí)將鉆套缺口轉(zhuǎn)至螺釘處，即可取出鉆套。削邊的方向應(yīng)考慮刀具的旋向，以免鉆套自動(dòng)脫出。根據(jù)加工5—通孔與5—沉孔的要求可以先鉆再擴(kuò)，后用平頭鉆三次加工，也可以用鉆—擴(kuò)復(fù)合刀具一次加工獲得。本次設(shè)計(jì)利用復(fù)合刀具一次加工。但綜合考慮采用快換鉆套。鉆模板的結(jié)構(gòu)如圖3—3所示：1—圓柱銷(xiāo)2—鉆模板3—支撐釘4—螺釘5—快換鉆套6—菱形螺母圖3—3鉸鏈?zhǔn)姐@模板夾具方案與夾具體的設(shè)計(jì)1.夾具體設(shè)計(jì)由可設(shè)計(jì)夾具體，材料為HT200，因?yàn)閵A具體為鑄件，應(yīng)進(jìn)行人工失效處理，具體加工技術(shù)要求及結(jié)構(gòu)見(jiàn)夾具體零件圖。2.夾具方案根據(jù)曲柄板形狀特點(diǎn)并由知應(yīng)選擇軸向方向?yàn)閵A緊的方向，曲柄板上端面及底面為被夾緊的兩面。并選擇夾緊機(jī)構(gòu)為螺旋加緊機(jī)構(gòu)。裝夾時(shí)，擰緊螺母，通過(guò)開(kāi)口墊圈，將工件端面牢固的壓在定位原件上，活動(dòng)V形塊通過(guò)彈簧的作用對(duì)工件起到一定的輔助夾緊作用。其加緊結(jié)構(gòu)如圖2—4所示1—分度盤(pán)2—支撐釘3—開(kāi)口墊圈4—螺母5—雙頭螺柱圖3—4螺旋夾緊機(jī)構(gòu)結(jié)構(gòu)圖由以上各主要原件的設(shè)計(jì)，將各局部連成以整體，夠成鉆模板的裝配圖〔見(jiàn)裝配圖〕。3.定位誤差分析該夾具定位基準(zhǔn)與設(shè)計(jì)基準(zhǔn)均為螺栓桿軸線，基準(zhǔn)不重合誤差為零?；鶞?zhǔn)位置誤差取決于Φ30H8孔和Φ30f7配合間隙，可確定最大配合間隙為=0.033+0.041=0.074mm,所以定位誤差0.074mm。工件尺寸80mm，公差取12級(jí)，查表IT12=0.3，所以加工誤差=0.3mm，定位誤差</3,此定位方案可行。4.夾緊力分析夾緊力是滿(mǎn)足定位可靠，夾具可行的因素。夾緊力不能太小，否那么加工時(shí)產(chǎn)生位移破壞定位，但也不能太大，否那么工件易變形本次加工孔徑較小，所需夾緊力也較小，所設(shè)計(jì)的夾緊機(jī)構(gòu)能滿(mǎn)足加工要求。結(jié)論此次畢業(yè)設(shè)計(jì)的內(nèi)容主要有兩個(gè)方面：曲柄板的加工工藝設(shè)計(jì)和夾具的設(shè)計(jì)。主要目的：在于通過(guò)對(duì)曲柄板加工工藝的設(shè)計(jì)，熟悉和掌握零件從毛坯材料選擇到成品過(guò)程，培養(yǎng)實(shí)際生產(chǎn)中產(chǎn)品設(shè)計(jì)能力；另外通過(guò)對(duì)夾具的設(shè)計(jì)，熟悉和掌握夾具的根本知識(shí)和設(shè)計(jì)原那么。通過(guò)本次的畢業(yè)設(shè)計(jì)，使我能夠?qū)?shū)本的知識(shí)做進(jìn)一步的了解與學(xué)習(xí)，工藝的設(shè)計(jì)，能使我們更加了解毛坯材料的選擇，材料的熱處理，加工方法的選擇，加工余量確實(shí)定，更加熟悉了工藝規(guī)程和先進(jìn)的加工工藝，學(xué)習(xí)到了工藝的制定過(guò)程，工藝卡片的制作，工藝手冊(cè)的查詢(xún)等方面的知識(shí)，先制定合理的加工工序，再選用適宜的機(jī)床，查工藝手冊(cè)定適宜的毛坯，再查進(jìn)給、切削速度、轉(zhuǎn)速，計(jì)算實(shí)際轉(zhuǎn)速和時(shí)間完成工藝卡片；通過(guò)專(zhuān)用夾具的設(shè)計(jì)，使我們掌握了專(zhuān)用夾具的設(shè)計(jì)步驟及過(guò)程，六點(diǎn)定位原理，通過(guò)設(shè)計(jì)定位元件來(lái)實(shí)現(xiàn)設(shè)計(jì)標(biāo)準(zhǔn)，通過(guò)夾緊力的計(jì)算選用夾緊裝置，對(duì)毛坯夾緊的原那么，最終完成零件的加工到達(dá)設(shè)計(jì)的要求。腳踏實(shí)地，認(rèn)真嚴(yán)謹(jǐn)，實(shí)事求是的學(xué)習(xí)態(tài)度，不怕困難、堅(jiān)持不懈、吃苦耐勞的精神是我在這次設(shè)計(jì)中最大的收益。我相信通過(guò)畢業(yè)設(shè)計(jì)不僅提升了對(duì)我大學(xué)期間所學(xué)根本專(zhuān)業(yè)知識(shí)綜合運(yùn)用也鍛煉了我們實(shí)際解決工程實(shí)際的能力，而且讓我們對(duì)所學(xué)的知識(shí)有了更加深刻的理解，對(duì)我們以后的學(xué)習(xí)、工作有了更大的幫助，為我們留下了珍貴的經(jīng)驗(yàn)。致謝歷經(jīng)了近兩個(gè)月的不懈努力，設(shè)計(jì)及論文已經(jīng)完成。從最初的茫然，到慢慢的進(jìn)入狀態(tài)，再到對(duì)思路逐漸的清晰，，緊張而又充實(shí)的畢業(yè)設(shè)計(jì)終于落下了帷幕。本論文是在指導(dǎo)老師程顯侖老師的悉心指導(dǎo)下完成的。老師淵博的專(zhuān)業(yè)知識(shí)，嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度，精益求精的工作作風(fēng)，誨人不倦的高尚師德，嚴(yán)以律己、寬以待人的崇高風(fēng)范，樸實(shí)無(wú)華、平易近人的人格魅力對(duì)我影響深遠(yuǎn)。不僅是我樹(shù)立了遠(yuǎn)大的學(xué)術(shù)目標(biāo)、掌握了根本的研究方法，還使我明白了許多待人接物與人處事的道路。本論文從選題到完成，每一步都是在程老師的指導(dǎo)下完成了，傾注了老師大量的心血，在此更要感謝程老師，是在他的細(xì)心指導(dǎo)和關(guān)心，我才能夠順利的完成畢業(yè)設(shè)計(jì)及論文。還有在我的學(xué)業(yè)和設(shè)計(jì)中無(wú)不傾注著老師們辛勤的汗水和心血，在此我要向所有的老師致以最衷心的感謝和深深的敬意，同時(shí)感謝我的同學(xué)和朋友，在我寫(xiě)論文的過(guò)程中給予我了很多素材，還在論文的撰寫(xiě)和排版燈過(guò)程中提供熱情的幫助。由于我專(zhuān)業(yè)知識(shí)水平有限，所寫(xiě)論文難免有缺乏之處，懇請(qǐng)各位老師和學(xué)友批評(píng)和指正！參考文獻(xiàn)[1]李曉沛、張琳娜、趙鳳霞主編.簡(jiǎn)明公差標(biāo)準(zhǔn)應(yīng)用手冊(cè)【M】.上海：上海科學(xué)技術(shù)出版社.2005.[2]胡荊生主編.公差配合與技術(shù)測(cè)量根底【M】.北京：中國(guó)勞動(dòng)社會(huì)保障出版社.2006.[3]中國(guó)機(jī)械工程學(xué)會(huì)編.形狀和位置公差【M】.北京：中國(guó)方案出版社.2004.[4]于駿一主編．典型零件制造工藝【M】．北京：機(jī)械工業(yè)出版社，1989.[5]莫雨松、李碩根主編．互換性與技術(shù)測(cè)量【M】．北京：中國(guó)計(jì)量出版社，1988.[6]馬賢智主編．機(jī)械加工余量與公差手冊(cè)【M】．北京：中國(guó)標(biāo)準(zhǔn)出版社，1994.[7]上海金屬切削技術(shù)協(xié)會(huì)主編．金屬切削手冊(cè)【M】．上?？茖W(xué)技術(shù)出版社，1984.[8]余光國(guó)、馬俊、張興發(fā)主編．機(jī)床夾具設(shè)計(jì)【M】．重慶：重慶大學(xué)出版社，1995.[9]薛源順主編.機(jī)床夾具設(shè)計(jì).北京：機(jī)械工業(yè)出版社【M】.1992[10]東北重型機(jī)械學(xué)院等．機(jī)床夾具設(shè)計(jì)手冊(cè)【M】．上海：上?？茖W(xué)技術(shù)出版社，1979[11]陳宏鈞主編．機(jī)械零件切削加工工藝與技術(shù)標(biāo)準(zhǔn)實(shí)用手冊(cè)【M】．1996[12]鄧文英、宋立宏.金屬工藝學(xué)【M】.北京:高等教育出版社.2008[13]王啟平.機(jī)床夾具設(shè)計(jì)【M】.哈爾濱：哈爾濱工業(yè)大學(xué)出版社.1988[14]王先逵主編.機(jī)械加工工藝手冊(cè)【M】.北京：機(jī)械工業(yè)出版社.2007附錄英文資料JigsandFixturesTheworkpiecemustbelocatedrelativetothecuttingtool,andbesecuredinthatposition.Aftertheworkpiecehasbeenmarkedout,itisstillnecessarytopositionitwithrespecttothemachinemovements,andtoclamitinthatpositionbeforemachiningisstarted.Whenseveralidenticalworkpiecearetobeproduced,theneedtomarkouteachpartiseliminatedbytheusedofjigsandfixture,butifacastingorforgingisinvolved,atrialworkpieceismarkedout,toensurethattheworkpiececanbeproducedfromit,andtobeensurethatribs,core,ect.Havenotbecomemisplaced.Jigsandfixturesarealikeinthattheybothincorporatedevicestoensurethattheworkpieceiscorrectlylocatedandclamped,buttheydifferinthatjigsincorporatemeansoftoolguidingduringtheactualcuttingoperation,andfixturesdonot.Inpractice,theonlycuttingtoolsthatcanbeguidedwhileactuallycuttingaredrills,reamers,andsimilarcutters,andsojigsareassociatedwithdrillingoperations,andfixtureswithalloperations.Fixturemayincorporatemeansofsettingthecuttingtoolsrelativetothelocationsystem.Theadvantagesofjigsandfixturescanbesummarizedasfollows:1.Markingoutandothermeasuringandsettingoutmethodsareeliminated.2.Unskilledworkersmayproceedconfidentlyandquicklyintheknowledgethattheworkpiececanbepositioncorrectly,andtoolsguidedorset.3.Theassemblyofpartsisfacilitated,sinceallcomponentswillbeidenticalwithinsmalllimits,and‘trying’andfilingofworkiseliminated.4.Thepartswillbeinterchangeable,andtheproductissoldoverawidearea,theproblemofpartswillbesimpliyed.Boltholesoftenhave1.5mmoreven3.0mmclearanceforthebolt,andthereadermaydoubtthenecessityofmakingprecisionjigsforsuchwork.Itmustberememberedthatthejigs,oncemade,willbeusedonmanycomponents,andtheextracostofanaccuratelymadejigisspreadoveralargeoutput.Forthermore,itissurprisinghowsmallerrorsaccumulateinamechanismduringitsassembly.Whenaclearanceisspecified,itisbettertoensureitsobservance,ratherthantoallowcarelessmarkingoutandmachiningtoencroachuponit.Thelocationofworkpiece.Aworkpieceinspacehassixdegreeoffreedom.ConsiderthesefreedomwithrespecttothethreemutuallyperpendicularaxesXX,YY,andZZ.Thebodycanmovealonganyoftheseaxe;itthereforehasthreefreedomoftranslation.Itcanalsorotateaboutanyofthethreeaxes;itthereforehasthreefreedomsofrotation.Thetotalnumberoffreedomsissix.Whenworkpieceislocated,asmanyofthesefreedomaspossiblemustbeeliminated,toensurethattheoperationisperformedwiththerequiredaccuracy.Accuracyisensurebymachiningsuitablelocationfeatureasearlyaspossible,andusingthemforalllocation,unlessotherconsiderationsmeanthatotherlocationfeaturesmustbeused.Ifnecessary,thenewlocationfeaturesmustbemachinedasaresultoflocationfromtheformerlocationfeature.Successfulfixturedesignsbeginwithalogicalandsystematicplan.Withacompleteanalysisofthefixture'sfunctionalrequirements,veryfewdesignproblemsoccur.Whentheydo,chancesaresomedesignrequirementswereforgottenorunderestimated.Theworkpiece,processing,tooling,andavailablemachinetoolsmayaffecttheextentofplanningneeded.Preliminaryanalysismaytakefromafewhoursuptoseveraldaysformorecomplicatedfixturedesigns.Fixturedesignisafive-stepproblem-solvingprocess.Thefollowingisadetailedanalysisofeachstep.1.DefineRequirementsToinitiatethefixture-designprocess,clearlystatetheproblemtobesolvedorneedstobemet.Statetheserequirementsasbroadlyaspossible,butspecificallyenoughtodefinethescopeofthedesignproject.Thedesignershouldasksomebasicquestions:Isthenewtoolingrequiredforfirst-timeproductionortoimproveexistingproduction?Ifimprovinganexistingjob,isthegoalgreateraccuracy,fastercycletimes,orboth?Isthetoolingintendedforonepartoranentirefamilyofparts?Thetoolingdesignermustdeterminehowmuchfreedomandinputthereisoneachproject.Ifmanychoicesregardingmachinetools,operations,andcuttingtoolshavealreadybeenmade,thedesigner'srolewillhavearelativelynarrowfocus.2.Gather/AnalyzeInformationCollectallrelevantdataandassembleitforevaluation.Themainsourcesofinformationarethepartprint,processsheets,andmachinespecifications.Makesurethatpartdocumentsandrecordsarecurrent.Forexample,verifythattheshopprintisthecurrentrevision,andtheprocessinginformationisup-to-date.Checkwiththedesigndepartmentforpendingpartrevisions.Animportantpartoftheevaluationprocessisnotetaking.Complete,accuratenotesallowdesignerstorecordimportantinformation.Withthesenotes,theyshouldbeabletofillinallitemsonthe"ChecklistforDesignConsideration"Allideas,thoughts,observations,andanyotherdataaboutthepartorfixturearethenavailableforlaterreference.Itisalwaysbettertohavetoomanyideasaboutaparticulardesignthantoofew.Fourcategoriesofdesignconsiderationsneedtobetakenintoaccountatthistime:workpiecespecifications,operationvariables,availabilityofequipment,andpersonnel.Thesecategories,whileseparatelycoveredhere,areactuallyinterdependent.Eachisanintegralpartoftheevaluationphaseandmustbethoroughlythoughtoutbeforebeginningthefixturedesign.Workpiecespecificationsusuallyarethemostimportantfactorsandhavethelargestinfluenceonthefixture'sfinaldesign.Typically,theseconsiderationsincludethesizeandshapeofthepart,theaccuracyrequired,thepropertiesofthepartmaterial,thelocatingandclampingsurfaces,andthesizeoftherun.Operationvariablesincludethetypeofoperationsrequiredtomakethepart,numberofoperationsperformed,sequenceofoperations,inspectionrequirements,andtimerestrictions.Availabilityofequipmentrequiredtomachine,assemble,andinspectapartoftendetermineswhetherthefixtureisdesignedforasinglepartormultipleparts.Aprocessengineersometimesselectstheequipmenttomachinepartsbeforethetoolingdesignerbeginsthedesign.Thetoolingdesignershouldverifywhatequipmentwillbeusedforeachoperation.Personnelconsiderationsdealwiththeenduser,oroperator,oftheequipment.Fixturedesignersshouldputthemselvesinthemachineoperator'sshoesandconsideralltheoperationalscenariostheycan.Designersshouldconsidernotonlycorrectusageofthefixture,butalsopossibleincorrectusage.Theymustask,"Isthereanywayformetohurtmyselfwhileoperatingthisequipment?"Additionalfactorsusuallyconsideredinthiscategoryareoperatorfatigue,efficiency,economyofmotion,andthespeedoftheoperation.Thedesigneralsomustknowandunderstandthegeneralaspectsofdesignsafetyandallappropriategovernmentandcompanysafetyrulesandcodes.3.DevelopSeveralOptionsThisphaseofthefixture-designprocessrequiresthemostcreativity.Atypicalworkpiececanbelocatedandclampedseveraldifferentways.Thenaturaltendencyistothinkofonesolution,thendevelopandrefineitwhileblockingoutother,perhapsbettersolutions.Adesignershouldbrainstormforseveralgoodtoolingalternatives,notjustchooseonepathrightaway.Duringthisphase,thedesigner'sgoalshouldbeaddingoptions,notdiscardingthem.Intheinterestofeconomy,alternativedesignsshouldbedevelopedonlyfarenoughtomakesuretheyarefeasibleandtodoacostestimate.Thedesignerusuallystartswithatleastthreeoptions:permanent,modular,andgeneral-purposeworkholding.Eachoftheseoptionshasmanyclampingandlocatingoptionsofitsown.Themorestandardlocatingandclampingdevicesthatadesignerisfamiliarwith,themorecreativehecanbe.Areasforlocatingapartincludeflatexteriorsurfaces,cylindricalandcurvedexteriorsurfaces,andinternalfeatures(suchasholesandslots).Thechoiceofstandardlocatingdevicesisquiteextensive.Similarly,therearecountlesswaystoclampapart,usingawidearrayofstandardclampingdevices.Forexample,aworkpiececanbeclampedfromthetop,orbygrippingitsoutsideedgeoraninternalsurface.4.ChoosetheBestOptionThefourthphaseofthetool-designprocessisacost/benefitanalysisofdifferenttoolingoptions.Somebenefits,suchasgreateroperatorcomfortandsafety,aredifficulttoexpressindollarsbutarestillimportant.Otherfactors,suchastoolingdurability,aredifficulttoestimate.Inanalyzingfixturecosts,theemphasisisoncomparingonemethodtoanother,ratherthanfindingexactcosts.Estimatesareacceptable.Sometimesthesemethodscomparebothproposedandexistingfixtures,sothat,wherepossible,actualproductiondatacanbeusedinsteadofestimates.Toevaluatethecostofanyworkholdingalternative,firstestimatetheinitialcostofthefixture.Tomakethisestimate,drawanaccuratesketchofthefixture.Numberandlisteachpartandcomponentofthefixtureindividually.Hereitisimportanttohaveanorderlymethodforoutliningthisinformation.5.ImplementtheDesignThefinalphaseofthefixture-designprocessconsistsofturningthechosendesignapproachintoreality.Finaldetailsaredecided,finaldrawingsaremade,andthetoolingisbuiltandtested.Usestandardcomponents.Theeconomiesofstandardizedpartsapplytotoolingcomponentsaswellastomanufacturedproducts.Standard,readilyavailablecomponentsincludeclamps,locators,supports,studs,nuts,pins,andahostofotherelements.Mostdesignerswouldneverthinkofhavingtheshopmakecapscrews,bolts,ornutsforafixture.Likewise,nostandardtoolingcomponentsshouldbemadein-house.Thefirstruleofeconomicdesignis:Neverbuildanycomponentyoucanbuy.Commerciallyavailabletoolingcomponentsaremanufacturedinlargequantitiesformuchgreatereconomy.Inmostcases,thecostofbuyingacomponentislessthan20%ofthecostofmakingit.Laborisusuallythegreatestcostelementinthebuildingofanyfixture.Standardtoolingcomponentsareonewaytocutlaborcosts.Browsethroughcatalogsandmagazinestofindnewproductsandapplicationideastomakedesignssimplerandlessexpensive.Useprefinishedmaterials.Prefinishedandpreformedmaterialsshouldbeusedwherepossibletolowercostsandsimplifyconstruction.Thesematerialsincludeprecision-groundflatstock,drillrod,structuralsections,casttoolingsections,precasttoolingbodies,toolingplates,andotherstandardpreformedmaterials.Includingthesematerialsinadesignbothreducesthedesigntimeandlowersthelaborcost.Keeptolerancesasliberalaspossible.Themostcost-effectivetoolingtoleranceforalocatorisapproximately30%to50%oftheworkpiece'stolerance.Tightertolerancesnormallyaddextracosttothetoolingwithlittlebenefittotheprocess.Wherenecessary,tightertolerancescanbeused,buttightertolerancesdonotnecessarilyresultinabetterfixture,onlyamoreexpensiveone.Simplifytoolingdetails.Elaboratedesignsoftenaddlittleornothingtothefunctionofthefixture.Moreoften,apowerclampcandothesamejobatafractionofthecost.Keepthefunctionandoperationofafixtureassimpleaspossible.Thelikelihoodofbreakdownsandotherproblemsincreaseswithcomplexdesigns.Theseproblemsmultiplywhenmovingpartsareaddedtothedesign.Misalignment,inaccuracy,wear,andmalfunctionscausedbychipsanddebriscancausemanyproblemsinthebestfixturedesigns.Reducingdesigncomplexityalsoreducesmisunderstandingsbetweenthedesignerandthemachineoperator.Wheneverpossible,afixture'sfunctionandoperationshouldbeobvioustotheoperatorwithoutinstructions.Oncesketchesandthebasicfixturedesignhavebeencompleted,finalengineeringdrawings,alsocalledshopprints,areusedinthetoolroomtobuildthefixture.Theeasiestwaytoreducemanualdrawingtimeisbysimplifyingthedrawing.Wordsorsymbolsshouldbeusedinplaceofdrawndetailswherepractical.Allextraorunnecessaryviews,projections,anddetailsshouldbeeliminatedfromthedrawing.Drawingacompleteclampassembly,forexample,addsverylittletothetotaldesign.Simplyshowingthenoseoftheclamp,drawninitsproperrelationtotheworkpieceandlabeledwithitspartnumber,conveysthesameinformationinafractionofthetime.Fordrawingsthatrequiremoredetail,usetracingtemplatestoreducedrawingtime.Thesetemplatesshowmoststandardcomponentsinseveralviews.Ifnecessary,theymaybeenlargedorreducedonacopiertoanyscaleneededforadrawing.Oncethepropertracingtemplateisselected,simplyslipitunderthedrawingsheetandalignitwiththedrawing.Whenthetemplateisproperlypositioned,tapeitdownandtracethecomponentonthedrawingsheet.Tracingtemplatessavedrawingtimeandimprovethequalityofthedrawing.Computersarerapidlyreplacingdrawingboardsasthepreferredtoolforpreparingengineeringdrawings.Almosteveryareaofdesignisaffectedbythecomputer.Computers,fromlargemainframestomicros,arebecomingstandardequipmentinmanydesigndepartments.Usingastandardlibraryindesigningthefixturedramaticallyreducesdrawingtime.Allcomponentsaredrawntofullscaleinavarietyofviews.Scalingdownisbestdoneinthefinaldrawing,notwhenstoringstandard-componentdrawings.Storingalargefixturebaseat1/4scaledoeslittlegood,becauseallcomponentswillhavetobe1/4scaletofitonit.Foreaseofuse,allcomponentsshouldbestoredatfullscale.Eachcomponentcanbecalledupfromthelibraryandplacedonthedrawingwhereitisrequired.Oncedrawingshavebeenthoroughlychecked,thenextstepisactuallybuildingtheactualfixture.Duringthebuildingstage,thedesignershouldmakesurethetoolroompersonnelknowexactlywhatmustbedonewhenmakingthefixture.Byperiodicallycheckingwiththefixturebuilder,thedesignercanhelpeliminateanypossiblemisunderstandingsandspeedthebuildingprocess.Ifthereareanydifficultieswiththedesign,thedesignerandbuilder,workingtogether,cansolvetheproblemswithaminimumoflosttime.MACHINABILITYThemachinabilityofamaterialusuallydefinedintermsoffourfactors:Surfacefinishandintegrityofthemachinedpart;Toollifeobtained;Forceandpowerrequirements;Chipcontrol.Thus,goodmachinabilitygoodsurfacefinishandintegrity,longtoollife,andlowforceAndpowerrequirements.Asforchipcontrol,longandthin(stringy)curedchips,ifnotbrokenup,canseverelyinterferewiththecuttingoperationbybecomingentangledinthecuttingzone.Becauseofthecomplexnatureofcuttingoperations,itisdifficulttoestablishrelationshipsthatquantitativelydefinethemachinabilityofamaterial.Inmanufacturingplants,toollifeandsurfaceroughnessaregenerallyconsideredtobethemostimportantfactorsinmachinability.Althoughnotusedmuchanymore,approximatemachinabilityratingsareavailableintheexamplebelow.MachinabilityOfSteelsBecausesteelsareamongthemostimportantengineeringmaterials(asnotedinChapter5),theirmachinabilityhasbeenstudiedextensively.Themachinabilityofsteelshasbeenmainlyimprovedbyaddingleadandsulfurtoobtainso-calledfree-machiningsteels.ResulfurizedandRephosphorizedsteels.Sulfurinsteelsformsmanganesesulfideinclusions(second-phaseparticles),whichactasstressraisersintheprimaryshearzone.Asaresult,thechipsproducedbreakupeasilyandaresmall;thisimprovesmachinability.Thesize,shape,distribution,andconcentrationoftheseinclusionssignificantlyinfluencemachinability.Elementssuchastelluriumandselenium,whicharebothchemicallysimilartosulfur,actasinclusionmodifiersinresulfurizedsteels.Phosphorusinsteelshastwomajoreffects.Itstrengthenstheferrite,causingincreasedhardness.Hardersteelsresultinbetterchipformationandsurfacefinish.Notethatsoftsteelscanbedifficulttomachine,withbuilt-upedgeformationandpoorsurfacefinish.Thesecondeffectisthatincreasedhardnesscausestheformationofshortchipsinsteadofcontinuousstringyones,therebyimprovingmachinability.LeadedSteels.Ahighpercentageofleadinsteelssolidifiesatthetipofmanganesesulfideinclusions.Innon-resulfurizedgradesofsteel,leadtakestheformofdispersedfineparticles.Leadisinsolubleiniron,copper,andaluminumandtheiralloys.Becauseofitslowshearstrength,therefore,leadactsasasolidlubricantandissmearedoverthetool-chipinterfaceduringcutting.Thisbehaviorhasbeenverifiedbythepresenceofhighconcentrationsofleadonthetool-sidefaceofchipswhenmachiningleadedsteels.Whenthetemperatureissufficientlyhigh-forinstance,athighcuttingspeedsandfeeds—theleadmeltsdirectlyinfrontofthetool,actingasaliquidlubricant.Inadditiontothiseffect,leadlowerstheshearstressintheprimaryshearzone,reducingcuttingforcesandpowerconsumption.Leadcanbeusedineverygradeofsteel,suchas10xx,11xx,12xx,41xx,etc.LeadedsteelsareidentifiedbytheletterLbetweenthesecondandthirdnumerals(forexample,10L45).(Notethatinstainlesssteels,similaruseoftheletterLmeans“l(fā)owcarbon,”aconditionthatimprovestheircorrosionresistance.)However,becauseleadisawell-knowntoxinandapollutant,thereareseriousenvironmentalconcernsaboutitsuseinsteels(estimatedat4500tonsofleadconsumptioneveryyearintheproductionofsteels).Consequently,thereisacontinuingtrendtowardeliminatingtheuseofleadinsteels(lead-freesteels).Bismuthandtinarenowbeinginvestigatedaspossiblesubstitutesforleadinsteels.Calcium-DeoxidizedSteels.Animportantdevelopmentiscalcium-deoxidizedsteels,inwhichoxideflakesofcalciumsilicates(CaSo)areformed.Theseflakes,inturn,reducethestrengthofthesecondaryshearzone,decreasingtool-chipinterfaceandwear.Temperatureiscorrespondinglyreduced.Consequently,thesesteelsproducelesscraterwear,especiallyathighcuttingspeeds.StainlessSteels.Austenitic(300series)steelsaregenerallydifficulttomachine.Chattercanbesproblem,necessitatingmachinetoolswithhighstiffness.However,ferriticstainlesssteels(also300series)havegoodmachinability.