半自動液壓專用銑床液壓系統(tǒng)的設計【說明書+CAD】
半自動液壓專用銑床液壓系統(tǒng)的設計【說明書+CAD】,說明書+CAD,半自動液壓專用銑床液壓系統(tǒng)的設計【說明書+CAD】,半自動,液壓,專用,銑床,系統(tǒng),設計,說明書,仿單,cad
設計任務書一、 機床對液壓傳動系統(tǒng)的具體參數(shù)要求液壓缸名稱負載力(N)移動件重力(N)(速度M/min)行程(MM)啟動時間(S)定位夾緊缸運動時間 (S)快進工進快退定位液壓缸20020101夾緊液壓缸400040151進給液壓缸2000150060.356快進工進0.5 30080二.機床類型及動作循環(huán)要求:設計一臺用成型銑刀在工件上加工出成型面的液壓專用銑床,要求機床工作臺一次可安裝兩只工件,并能同時加工。機床工作循環(huán)為:手工上料 按電鈕 自動定位夾緊 工作臺快進 銑削進給 工作臺快退 夾具松開 手工卸料。 編號_畢業(yè)設計(論文)題目:半自動液壓專用銑床液壓系統(tǒng)的設計無錫技師 學院(系) 數(shù)控 專業(yè)學 號: 23 學生姓名: 張鵬 指導教師: 孫亞波 (職稱: ) 范峰 (職稱: ) 年 月設計任務書一、 機床對液壓傳動系統(tǒng)的具體參數(shù)要求液壓缸名稱負載力(N)移動件重力(N)(速度M/min)行程(MM)啟動時間(S)定位夾緊缸運動時間 (S)快進工進快退定位液壓缸20020101夾緊液壓缸400040151進給液壓缸2000150060.356快進工進0.5 30080二.機床類型及動作循環(huán)要求:設計一臺用成型銑刀在工件上加工出成型面的液壓專用銑床,要求機床工作臺一次可安裝兩只工件,并能同時加工。機床工作循環(huán)為:手工上料 按電鈕 自動定位夾緊 工作臺快進 銑削進給 工作臺快退 夾具松開 手工卸料。摘 要 本次畢業(yè)設計的是半自動液壓專用銑床的液壓設計,專用銑床是根據(jù)工件加工需要,以液壓傳動為基礎(chǔ),配以少量專用部件組成的一種機床。在生產(chǎn)中液壓專用銑床有著較大實用性,可以以液壓傳動的大小產(chǎn)生不同性質(zhì)的銑床。此次設計主要是將自己所學的知識結(jié)合輔助材料運用到設計中,尤其是一些計算、繪圖等細小方面。在設計過程中最主要的是圖紙的繪制,這不僅可以清楚的將所設計的內(nèi)容完整的顯示出來,還能看出所學知識是否已完全掌握了。 整個主要設計過程分成六個部分:參數(shù)的選擇、方案的制定、圖卡的編制、專用銑床的設計、液壓系統(tǒng)的設計以及最后有關(guān)的驗算。主體部分基本在圖的編制和液壓系統(tǒng)的設計兩部分中完成的。 工序分為:手工上料 按電鈕 自動定位夾緊 工作臺快進 銑削進給 工作臺快退 夾具松開 手工卸料。 關(guān)鍵詞:銑削進給,液壓傳動,夾具目 錄第一章、緒論 -1 1.1設計目的-11.2設計內(nèi)容及要求1.2.1機床類型及動作循環(huán)要求 1.2.2機床對液壓傳動系統(tǒng)的具體參數(shù)要求第二章、液壓系統(tǒng)的設計 2.1 液壓系統(tǒng)的設計與計算 2.1.1分析工況及設計要求,繪制液壓系統(tǒng)草圖 2.1.2液壓缸的負載計算2.1.3確定系統(tǒng)的工作壓力2.1.4確定液壓缸的幾何參數(shù)2.2 確定液壓泵規(guī)格和電動機功率及型號2.2.1確定液壓泵規(guī)格2.2.2確定油液的壓力 2.3 確定各類控制閥2.4確定油箱容積與結(jié)構(gòu) 2.5選取液壓油第三章、液壓缸及液壓裝置的結(jié)構(gòu)設計 3.1確定液壓缸的結(jié)構(gòu)形式 3.2計算液壓缸主要零件的強度和鋼度3.3完成液壓缸的結(jié)構(gòu)設計和部分零件圖。第四章、管路系統(tǒng)壓力損失的計算第五章、系統(tǒng)熱平衡計算與油箱容積的計算第六章、結(jié)論致謝參考文獻附錄附錄A 液壓元件的規(guī)格附錄B 液壓系統(tǒng)圖第一章 緒論1.1設計目的畢業(yè)設計是培養(yǎng)學生綜合運用所學的基礎(chǔ)理論和專業(yè)理論知識,獨立解決機床設計問題的能力的一個重要的實踐性教學環(huán)節(jié)。因此,通過設計應達到下述目的。a初步掌握正確的設計思想和設計的基本方法步驟,鞏固深化和擴大所學的知識,培養(yǎng)理論聯(lián)系實際的工作方法和獨立工作能力。b獲得機床總體設計,結(jié)構(gòu)設計,零件計算,編寫說明書。繪制部件總裝圖(展開圖,裝配圖)和零件工作圖等方面的基本訓練及基本技能。c熟悉有關(guān)標準、規(guī)格、手冊和資料的應用。d對專用機床的夜壓系統(tǒng)初具分析能力和改進設計的能力。1.2設計內(nèi)容及要求1.2.1機床類型及動作循環(huán)要求:設計一臺用成型銑刀在工件上加工出成型面的夜壓專用銑床,要求機床工作臺一次可安裝兩只工件,并能同時加工。機床工作循環(huán)為:手工上料 按電鈕 自動定位夾緊 工作臺快進 銑削進給 工作臺快退 夾具松開 手工卸料。1.2.2機床對液壓傳動系統(tǒng)的具體參數(shù)要求液壓系統(tǒng)參數(shù)圖 液壓缸名稱負載力(N)移動件重力(N)(速度M/min)行程(MM)啟動時間(S)定位夾緊缸運動時間(S)快進工進快退定位液壓缸20020101夾緊液壓缸400040151進給液壓缸2000150060.356快進工進0.530080工作臺采用半導軌,導軌面的靜摩擦系數(shù)f=0.2動摩擦系數(shù)f=.0.1 第二章 設計步驟2.1液壓系統(tǒng)的設計與計算2.1.1分析工況及設計要求,繪制液壓系統(tǒng)草圖機床工況由題可知為: 定位液壓缸 夾緊液壓缸 工作臺進給液壓缸 定 位 夾 松 快進 工進 拔銷 緊 開 按設計要求希望系統(tǒng)結(jié)構(gòu)簡單,工作可靠,估計到系統(tǒng)的功率不會很大,且連續(xù)工作,所以決定采用單個定量泵、非卸荷式供油系統(tǒng).考慮到銑銷時可能有負的負載力產(chǎn)生,故采用回油節(jié)流調(diào)速的方法,為了提高夾緊缸的穩(wěn)定性與可靠性,夾緊系統(tǒng)采用單向閥與蓄能器的保壓回路,并能不用減壓閥,使夾緊油源壓力與系統(tǒng)的調(diào)節(jié)一致,以減少液壓元件的數(shù)量,簡化系統(tǒng)結(jié)構(gòu),定位后通過行程開控制二位四通電磁閥通點工作控制夾緊缸工作,并采用壓力繼電器,發(fā)訊使工作臺液壓工作以簡化電氣發(fā)訊與控制系統(tǒng),提高系統(tǒng)的可靠性.綜合上面考慮,可繪制出液壓系統(tǒng)圖. (見附頁)2.1.2液壓缸的負載計算:(1)定位液壓缸 已知負載力R=200N (慣性力與摩擦力可以忽略不計)(2)夾緊液壓缸已知負載力R=4000N (慣性力與摩擦力可以忽略不計)(3)工作臺液壓缸有效負載力R=200N (已知)慣性力Rm=ma=1500/9.8/(6/60-0)/0.5=30.6N(按等加速處理)摩擦力由液壓缸的密封阻力與滑臺運動的摩擦力組成,當密阻力按5%有效作用力估算時,總的摩擦阻力:Rf=0.05Rw+Fc=0.05*2000+0.2*1500=4000N故負載力:R=Rw+Rm+Rf=2000+30.6+400=2430.6N2.1.3確定系統(tǒng)的工作壓力因為夾緊液壓缸的作用很大,所以可以按其工作負載來選定系統(tǒng)的壓力由設計參考資料可以初定系統(tǒng)的壓力為0.8 1MPa,為使液壓缸體積緊湊,可以取系統(tǒng)的壓力為P1=1.5MPa2.1.4確定夜壓缸的幾何參數(shù)(1) 定位液壓缸的D=考慮到液壓缸的結(jié)構(gòu)與制造的方便性,以及插銷的結(jié)構(gòu)尺寸等因素,參考手冊-可以取D=32mm,d=16mm(2)夾緊液壓缸D=實取D=63mm, d=32mm(3)進給液壓缸因采用雙出桿液壓缸,所以D = 按工作壓力,可以選桿徑d=0.3D代入上上式得:D=一般可取背壓P2=0.5MPa(對低壓系統(tǒng)而言),代入上式有:D=取進給液壓缸系列化的標準尺寸為:D=63mm, d=20mm2.2確定液壓泵規(guī)格和電動機功率及型號2.2.1確定液壓泵規(guī)格(a)確定理論流量定位液壓缸最大的流量:Q1=A1v=D/4L/t=3.140.032/41010/1=8.0410m/s=0.4824L/min 夾緊液壓缸最大流量Q2=A1v=D/4L/t=3.140.063/41510/1=4.6810m/s=2.8L/min因為有兩個夾緊缸同時工作,所以Q2=2 Q2=22.8=5.6L/min進給液壓缸最大流量Q3=A2v=D-d)/4v=3.140.063-0.02)/46=0.0168m/s=1008L/min (b)確定液壓泵流量由于定位,夾緊,進給液壓缸是分時工作的,所以其中液壓缸的最大流量既是系統(tǒng)的最大理論流量,另外考慮到泄漏和益流閥的益流流量,可以取液壓泵流量為系統(tǒng)最大流量的1.1 1.3倍,現(xiàn)取1.2倍計算則有: Q泵=1.2Q3=1.216.8=20.16L/min采用低壓齒輪泵,則可選取CB-B25為系統(tǒng)的供油泵,其額定流量為25L/min,額定壓力為2.5Mpa,額定轉(zhuǎn)速為24.17r/s(1450r/min)(C)確定電動機功率及型號 電動機功率N=PQ/612=2525/6120.8=1.28KW按CB-B*型齒輪泵技術(shù)規(guī)格,查得驅(qū)動電動機功率為1.3KW,或取電動機功率略大一點的交流電機動機型號為JQ2 22 4額定功率為1.5KW,轉(zhuǎn)速為1450r/min2.2.2確定油液的壓力 (a)定位缸油液的壓力已知F=200N D=32mm d=16mm Q=0.4824L/min求:P1因為 F = A1 P = DP=3.14/40.032P1所以P1 = 2.48810Pa (b)夾緊缸油液的壓力已知F=4000N D=63mm d=32mm Q=5.6L/min求:P2因為 F = A1 P =DP=3.14/40.063P1所以P2 = 1.28383510Pa2.3確定各類控制閥系統(tǒng)工作壓力為1.5MPa,油泵額定最高壓力為2.5MPa,所以可以選取額定壓力大于或等于2.5MPa的各種元件,起流量按實際情況分別選取.目前,中低壓系統(tǒng)的液壓元件,多按6.3MPa系列的元件選取,所以可以選取.溢流閥的型號為: Y-25B工作臺液壓缸換向型號為:34D-25BY,快進二位二通電磁閥型號Q 10B;背壓閥型號為:B - 25B定位,夾緊系統(tǒng)的最大流量為2.8L/min,所以可以選取.單向閥型號為I 10B;換向閥型號24D-10B 23D-10B;單向順序閥型號為XI-B10B.蓄能器供油量僅作定位夾緊系統(tǒng)在工作臺快進,工進與快退時,補充泄漏和保持壓力之用,其補油量極其有限,所以可以按各種最小的規(guī)格選取,現(xiàn)取N Q 0.6/10 型膠囊式蓄能器,當P=15%時,其有效補油體積為V=0.07L。濾油器可選用型號為wv -25 - 180J的網(wǎng)式濾油器,過濾精度為180um壓力表可選用 Y 60 型量程6.3MPa的普通精度等級的量表,選用量程較高的壓力表可以避免在系統(tǒng)有壓力沖擊時經(jīng)常損壞,但量程選得過大會使觀察和調(diào)整的精度降低.管道通徑與材料:閥類一徑選定,管道的通徑基本上已經(jīng)決定,既管道的通徑同于閥類進出油口的通徑,只有在有特殊需要時才按管內(nèi)平均要求計算管道通徑.按標準:(1) 通徑25L/min流量處, 選用通徑的管道10L/min流量處, 選用通徑的管道為便于安裝,可以采取紫銅管,擴口接頭安裝方式.(2) 壁厚按強度公式有:p.d/2其中,紫銅的=250kgf/cm2為安全起見,可取P=2.5MPa來計算:122.5 12/2 25 =0.6mm82.5 8/2 25 =0.4mm所以可取12,壁厚1mm和8,壁厚0.8mm的紫銅管,考慮到擴口處管子的強度,壁厚可以略有增加,一般按常用紫銅管的規(guī)格選取即可(對低壓系統(tǒng)而言),對高壓系統(tǒng)必須進行計算。2.4確定油箱容積與結(jié)構(gòu) 因為是低壓系統(tǒng),油箱容積按經(jīng)驗公式計算:油箱容積V= ( )Q現(xiàn)取 V= = = 100L結(jié)構(gòu)可以采用開式,分力,電動機垂直安置式標準油箱。2.5.選取液壓油該系統(tǒng)為一般金屬切削機床液壓傳動,所以在環(huán)境溫度為-之間時,一般可選用號或號機械油。冷天氣用號機械油,熱天氣用號機械油。第三章 液壓缸及液壓裝置的結(jié)構(gòu)設計3.1確定液壓缸的結(jié)構(gòu)形式液壓缸的結(jié)構(gòu)形式是指他的類型,安裝方法,密封形式,緩沖結(jié)構(gòu),排氣等.定位與夾緊液壓缸均采用單出桿,缸體固定形式,為減少缸體與活塞體積,簡化結(jié)構(gòu),采用“”型密封圈;由于行程很短,運動部件質(zhì)量很小,速度也不大,不必考慮緩沖結(jié)構(gòu);排氣螺塞也可以由油塞接頭來代替.工作臺液壓缸采用裝配活塞,雙出桿,缸體固定定形式,采用雙出桿可以使活塞桿在工作時處于受拉伸應力狀態(tài),有利于提高活塞桿的穩(wěn)定性,并且可以減小活塞桿的直徑,活塞上才用單個“”型密封圈,另外,由于工作材料為鑄鐵,加工時粉塵及小片狀或針狀的鐵銷較多,所以有加上了一個防塵圈,夾緊液壓缸的的防塵圈也是鑒于同樣原因安放的.由于機床工作臺作直線進給運動,在運動方向上沒有嚴格的定位要求(這一點與一般鉆銷動頭液壓缸的要求有所區(qū)別),不必采用機構(gòu)??焱耸拢梢圆捎秒姎庑谐涕_關(guān)預先發(fā)訊,使三位四通換向閥切至中位,工作臺停住,避免剛性沖擊;排氣也采用松開油管進油螺塞的方法進行,而不設專門的放棄螺塞。3.2計算液壓缸主要零件的強度和鋼度定位夾緊油缸的內(nèi)油和長度較小,一般可以按厚壁筒強度計算公式來估計必須的厚壁,有公式:=/(-)當額定壓力Pn6.3MPa時,取鋼=b/n=4500/6=750kgf/cm2=75MPaPp = Pn 150% = 2.5 150% =3.75MPa將鋼,Pp的值及定位,夾緊液壓缸的直徑D代入計算公式可得:定3.2/2(-1)0.072cm=0. 72mm夾3.2/2(-1)0.142cm=1. 42mm工作臺液壓缸壁厚用薄壁筒計算公式來求:工 Pp D/2 = 3.75 6.3/2 75 = 0.158cm = 1.58mm從以上計算可以看出,對與小型底壓 ( D 100mm, Pn 2.5MPa ) 液壓缸按強度條件計算出來的缸壁厚度尺寸是很小的,因此,在設計這類液壓鋼事,可以先不計算,而直接按機械結(jié)構(gòu)尺寸的需要,主要是缸體與缸蓋的連接出的尺寸,及考慮到缸體缸度所需的基本厚度尺寸,直接設計制圖,然后進行強度校核.這樣做在一般的情況下,均可滿足強度要求.而對于高壓的液壓缸或鑄鐵材料的缸體、缸壁的強度估算是必要的這樣可以避免結(jié)構(gòu)設計圖的返工和修改。對于缸蓋,活塞桿聯(lián)接件,鑒于與上相同的原因,強度計算一般可以放在結(jié)構(gòu)設計后的強度校核中進行。3.3完成液壓缸的結(jié)構(gòu)設計和部分零件圖。液壓缸的活塞寬度,一般可取b 0.4D ,同時應該考慮密封圈安裝時的必要幾何尺寸,缸蓋應該考慮到進油及加工工藝要求,缸體連接處應考慮必要的導向與支撐的結(jié)構(gòu)尺寸。小型定位, 夾緊傳動液壓缸與傳動液壓缸在結(jié)構(gòu)與安裝方法上不盡相同,總之要使結(jié)構(gòu)設計達到結(jié)構(gòu)簡單、工藝性好、安裝方便、取材便利、強度足夠、要求輸出力、位移和功率,也要能達到設計要求。根據(jù)上述液壓缸的結(jié)構(gòu)特點及內(nèi)徑、桿徑、行程等要求,液壓缸的結(jié)構(gòu)設計(如圖A1)。第四章 管路系統(tǒng)壓力損失的計算由于定位、夾緊、回路在夾緊后的流量幾乎為零,即管路系統(tǒng)的壓力損失,主要應在工作臺液壓缸回路中進行計算。按快進時,最大流量來估計壓力損失 Q3 = 16.8L/ min來考慮(因泵的額定流量Q=25L/min)??倝毫p失 p=p沿+p局其中:p沿-管路中沿程阻力+損失之和p局-管路中局部阻力損失系各閥類元件的阻力之和一般,簡單的低壓金屬切削機床液壓系統(tǒng)中p 值可取(0.10.3) Pn(Pn為系統(tǒng)調(diào)整壓力)。壓力閥調(diào)整壓力的確定:Py=1.1Pn=1.1 * 1.5 =1.65MPa由于系統(tǒng)壓力在初步設計時一般取泵的額定壓力的50%70%目的是為了延長泵的壽命或減少噪音。所以泵源總有一定的壓力儲備,系統(tǒng)的調(diào)整壓力可在試車階段進一步調(diào)節(jié)。順序閥的控制壓力可以選擇為先動液壓缸最大起動壓值的150%200%,而必須比系統(tǒng)調(diào)整壓力低,順序閥的控制壓力可調(diào)節(jié)為0.60.7MPa。壓力蓄電器發(fā)訊時壓力必須比系統(tǒng)額定壓力值稍小一些 ,可調(diào)節(jié)1.41.5MPa。第五章 系統(tǒng)熱平衡計算與油箱容積的計算系統(tǒng)發(fā)熱量可以由功能守恒平均有效功率的概念,本設計中定位夾緊液壓泵功率很小,所以略去不計。第六章 畢業(yè)設計總結(jié)通過此次畢業(yè)設計,使自己有了更深層次地了解了設計液壓系統(tǒng)時的一些方法及過程以及繪制有關(guān)零件時應注意的一些細小環(huán)節(jié)。本次設計不算太好,只可以說大致完成了指導老師所提出的要求,畢竟在設計過程中對一些參數(shù)的選擇上還存在一些不太全面、不合理的選擇(選擇的參數(shù)有些太靠近極限)。在今后遇到類似的情況將重點對待參數(shù)的選擇以及計算。致謝:在整個設計過程中,我始終感覺到指導老師范老師和孫老師那種誨人不倦的高風亮節(jié),這將永遠激勵著我。在我遇到困難的時候,孫老師總是耐心的引導我將困難解決并指出我在設計過程中存在的一些細小的問題以及制圖中存在的問題。在此,我感謝孫老師和范老師在這次畢業(yè)設計中予以我的極大幫助。參考文獻1. 季名善,齊人光主編.液氣壓傳動.上海:機械工業(yè)出版社,20012. 王之櫟,王大康主編.機械設計綜合課程設計.北京: 機械工業(yè)出版社,20033. 胡荊生主編.公差配合與技術(shù)測量基礎(chǔ).北京:中國勞動社會保障出版社.20004. 陳海魁主編.機械制造工藝基礎(chǔ). 北京:中國勞動社會保障出版社.20005. 陳??骶?機械基礎(chǔ). 北京:中國勞動社會保障出版社.20016. 趙家齊主編.機械制造工藝書. 北京: 機械工業(yè)出版社,20007. 孫麗媛主編.機械制造工藝及專用夾具設計指導. 治金工業(yè)出版社,2003液壓元件型號規(guī)格 序 號元 件 名 稱通 過 流 量q(L.min)型 號 規(guī) 格1低壓齒輪泵25CB-B252溢流閥25Y-253單向閥2.8I-10B4單向閥20.16B-25B5三位四通閥2534D-25BY6快進二位二通電磁閥2522D-25B7調(diào)速閥1Q-10B8二位四通換向閥2.824D-10B9單向閥2.8XI-B10B10壓力蓄電器DP1-63B11蓄能器NXQ-0.6/1012電動機JQ2-22-413壓力表Y-6014濾油器25WU-25180J15二位三通換向閥1023D-10B 液 壓 系 統(tǒng) 圖Milling a m ster comprising tool life compared to ball-mills H208514H20852. Ip and Loftus H208515H20852 demon- strated the competency of an inclined end mill machining strategy on 3-axis machines in producing low curvature surfaces. How- surface is decomposed into triangular patches. An occupancy test of the patches is conducted on a triangular-represented unit sphere Downloaded 11 Dec 2009 to 222.190.117.204. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm ever, to machine a surface with large curvature variation, it is necessary to determine a set of machining orientations and carry out multiple 3-axis machining operations in a sequential manner with respect to each of those orientations. Therefore, an effective machinability analysis is of critical importance to the successful implementation of multiple orientation 3-axis machining for cre- ating complex parts. Many researchers have studied machinability analysis and its closely related workpiece setup problem. Most of the approaches are based on visibility, which is essentially line-of-light accessi- bility. Su and Mukerjee H208516H20852 presented a method to determine ma- chinability of polyhedral objects. A convex enclosing object is constructed to make each face of the part orthogonally visible to to generate global visibility. Dhaliwal et al. H2085115H20852 presented a simi- lar approach for computing global accessibility cones for polyhe- dral objects, but with exact mathematical conditions and algo- rithms. Balasubramaniam et al. H2085116H20852 analyzed visibility by using computer hardware H20849graphics cardsH20850. Frank et al. H2085117H20852 analyzed two-dimensional H208492DH20850 global visibility on stereolithography H20849STLH20850 slices and searched the necessary machining orientations for fourth-axis indexable machining by executing a GREEDY search algorithm. All these visibility-based approaches determine the necessary condition for machinability; however, they ignore tool geometry and, therefore, true accessibility H20849machinabilityH20850 is not guaranteed. Figure 1 shows that the accessibility cone H20849H9251,H9252H20850 based on line-of-light visibility cannot guarantee the true accessi- bility using a sized tool in machining a segment ij. Su and Mukerjee H208516H20852 took into account the cutter information by constructing a new part model through offsetting the original part surface by the amount of the cutter radius. Machinability was further guaranteed by checking the topology of this offset part Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received October 13, 2004; final manuscript received August 8, 2005. Review conducted by D.-W. Cho. 454 / Vol. 128, MAY 2006 Copyright 2006 by ASME Transactions of the ASME Ye Li e-mail: yeliiastate.edu Matthew C. Frank Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, IA 50011 Machinability Flat End This paper presents of the strategy determines 3-axis machining operations file geometry from a of the line segments orthogonal to the axis machinability analysis respectively. This machinability analysis for the rapid machining. H20851DOI: 10.1 Keywords: machinability, 1 Introduction Machinability analysis is taking an increasingly important role as complex surfaces are used in the design of a wide variety of parts. Current computer-aided manufacturing H20849CAMH20850 software is readily capable of generating toolpaths given a set of surfaces of a part and a cutting orientation H208493-axis machiningH20850. However, deter- mining the setup orientation can be difficult and moreover, it may be very challenging to determine if the part can be created using machining at all. An appropriate setup orientation can guarantee an effective cutting of the surface, whereas an inappropriate one will leave too much material in certain regions. The advancement of 5-axis computer numerically controlled H20849CNCH20850 milling ma- chines seems to alleviate this situation; however, often the cost and/or difficulty of programming a 5-axis machine have limited their widespread use. Three-axis machines, as economical and technologically mature pieces of equipment, have been paid spe- cial attention with respect to complex surface machining if as- sisted with multisetup devices H20849e.g., a programmable indexerH20850. Suh and Lee H208511H20852 used a 3-axis machine with a rotary-tilt-type indexer to provide an alternative to 5-axis ball end milling. Suh et al. H208512H20852 provided a theoretic basis for machining with additional axes. Recently, Frank et al. H208513H20852 employed a 3-axis milling center with a fourth axis indexer as an effective rapid prototyping ma- chine. End mills have been shown to offer a better match to the part surface geometry, a higher material removal rate, and a longer Analysis for 3-Axis ethod for geometric machinability analysis. The implementation the machinability of a part being processed using a plurality of about a single axis of rotation for setup orientations. Slice eolithography model is used to map machinable ranges to each the polygonal chains of each slice. The slices are taken of rotation, hence, both two- and three-dimensional (2D and 3D) is calculated for perpendicular and oblique tool orientations, approach expands upon earlier work on 2D visibility manufacturing and prototyping of components using CNC 115/1.2137748H20852 tool accessibility, CNC machining, slice geometry the planes of the enclosing object. The part is then considered to be machinable from the normal-vector directions of the enclosing object planes. Later, computational geometry on the sphere was utilized to analyze visibility by Chen and Woo H208517H20852 who performed pioneering work on computational geometry algorithms that could be used for determining workpiece setup and machine selection. Tang et al. H208518H20852 formulated the problem of workpiece orientation as finding the maximum intersection of spherical polygons. Gan et al. H208519H20852 discussed the properties and construction of spherical maps and presented an efficient way to compute a visibility map from a Gaussian map. Chen et al. H2085110H20852 partitioned the sphere by spheri- cally convex polygons to solve the geometric problem of deter- mining an optimal workpiece orientation for 3-, 4-, and 5-axis ball end milling. A visibility map is generated by using the normal vectors of a specified portion of the surface of a part; therefore, it cannot guarantee global accessibility. Yang et al. H2085111H20852 computed visibility cones based on convex hull analysis, instead of relying on visibility maps. Yin et al. H2085112H20852 defined complete visibility and partial visibility, and presented a C-space-based method for com- puting visibility cones.Asculptured surface is approximated by its convex hull H2085111H20852, and the spherical algorithms H208517,13H20852 are used in the approach of Yin H2085112H20852. The convex hull may, in some cases, have a significant deviation from the true surface. Suh and Kang H2085114H20852 constructed a binary spherical map to compute the point vis- ibility cone in order to algebraically solve machining configura- tion problems, including workpiece setup orientation. The part Downloaded 11 Dec 2009 to 222.190.117.204. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm surface. This method is effective for the machinability analysis of a ball end cutter, but not for that of a flat end cutter, because the effective radius of a flat end cutter is variable with the change of tool tilting angle. Haghpassand and Oliver H2085118H20852 and Radzevich and Goodman H2085119H20852 considered both part surface and tool geom- etry. However, tool size was not taken into account because Gaussian mapping does not convey any size information of the part surface and/or the tool. Balasubramaniam et al. H2085116,20H20852 veri- fied tool posture from visibility results by collision detection be- fore interpolating the tool path for 5-axis machining. Over the past years, feature-based technologies have been an active field among the manufacturing research community. Regli H2085121H20852, Regli et al. H2085122H20852, and Gupta and Nau H2085123H20852 discussed feature accessibility and checked it by calculating the feature accessibility volume and testing the intersection of the feature accessibility volume with the part. Gupta and Nau H2085123H20852 recognized all machin- ing operations that could machine the part, generated operation plans, and checked and rated different plans according to design needs. A comprehensive survey paper on manufacturability by Gupta et al. H2085124H20852 reviewed representative feature-based manufac- turability evaluation systems. Shen and Shah H2085125H20852 checked feature accessibility by classifying the feature faces and analyzing the degree of freedom between the removal volume and the work- piece. The MEDIATOR system reported by Gaines et al. H2085126H20852 used the knowledge of manufacturing equipment to identify manufac- turing features on a part model. Accessibility is examined by test- ing the intersection of removal volumes with the part. Faraj H2085127H20852 discussed the accessibility of both 2.5-D positive and negative features. Other researchers presented featured-based approaches to determine workpiece setups H208512831H20852. Although feature-based approaches are capable tools to handle feature-based design, they cannot lend themselves to free-form surfaces where definable features may not exist. In addition, feature-based approaches suggest that all the geometric elements comprising of a feature are treated together as an entity. This actually imposes a constraint to the analysis of a part model. For example, it might be feasible to machine a portion of a part fea- ture in one orientation and then finish the remaining surfaces of the feature in one or more successive orientations. The current problem that this paper addresses is based on a rapid machining strategy proposed by Frank et al. H208513H20852 whereby a part is machined with a plurality of 3-axis machining operations from multiple setup orientations about a single axis of rotation. The strategy is implemented on a 3-axis CNC milling machine with a fourth-axis indexer H20849Fig. 2H20850. Round stock material is fixed between two opposing chucks and rotated between operations us- ing the indexer. For each orientation, all visible surfaces are ma- chined using simple layer-based tool-path planning. By setting the collision offset H20849bH20850H20849shown in the Fig. 2H20850 on each side of the workpiece, the implementation of rapid machining can avoid the risk of collision between tool holders and the holding chucks. The diameter of largest tool H20849D tmax H20850 used to calculate the collision offset H20849bH20850 makes the setting of collision offset for each new part unnecessary. The feature-free nature of this method suggests that Fig. 1 Accessibility based on light ray and a sized tool Journal of Manufacturing Science and Engineering it is unnecessary to have any surface be completely machined in any particular orientation. The goal is to simply machine all sur- faces after all orientations have been completed. The number of rotations required to machine a model is dependent on its geomet- ric complexity. Figure 3 illustrates the process steps for creating a typical complex part using this strategy. Currently, the necessary cutting orientations are determined by 2D visibility maps with tool access restricted to directions or- thogonal to the rotation axis. Cross-sectional slices of the geom- etry from an STL model are used for 2D visibility mapping. The visibility of those slices approximates the visibility of the entire surface of the part along the axis of rotation since the slices are generated orthogonal to that axis. The above literature review sug- gests that existing approaches to machinability cannot calculate the set of orientations for setups such that one can machine all machinable surfaces after all orientations, because either H20849iH20850 2D or three-dimensional H208493DH20850 visibility cones employed by the Fig. 2 Setup for rapid machining Fig. 3 Process steps for rapid machining MAY 2006, Vol. 128 / 455 visibility-based approaches convey no size information of the tool and workpiece and, therefore, cannot guarantee true accessibility; or H20849iiH20850 the feature-based approaches cannot cope with complex geometrically composed of a set of pointsH20850 is the intersection of the machinability of each point belonging to that feature. Similar to the concept of partial visibility H20849PVH20850, partial machinability Downloaded 11 Dec 2009 to 222.190.117.204. Redistribution subject to ASME license or copyright; see http:/www.asme.org/terms/Terms_Use.cfm H20849free-formH20850 surface machining because few traditional features can be identified on parts with free-form surfaces. An effective machinability analysis method is a prerequisite to the successful implementation of multisetup 3-axis end milling in order to achieve the needs of 4- and perhaps 5-axis machining.An effective machinability analysis method will determine, given a machining orientation and an end mill of a particular size, how much of the part surface can be machined with respect to this machining orientation. The focus of this paper is to present a feature-free machinability analysis that can determine the number of setups required to completely machine the surfaces of a part with one-axis-of-rotation setups. The machinability analysis method presented in this paper is unlike any previous work in its completely feature-free treatment of the part geometry. We reduce the surfaces of the part down to simple line segments on the slices; therefore, any CAD model can be exported as an STL file and studied. This approach is done because we are only assuming that the part is machined about one axis of rotation; therefore, it is much simpler to simply analyze the 2D slices rather than 3D surface geometry. The remainder of this paper is organized as follows. In Sec. 2, definitions that are used throughout this paper are presented. Sec- tion 3 discusses the machinability analysis method in further de- tail, and Sec. 4 presents the implementation of the machinability analysis approach. Last, conclusions and future research endeav- ors are provided. 2 Definitions Although previous researchers have defined the concepts of vis- ibility and machinability in their work, similar definitions are pro- vided first in this section to clarify the difference between visibil- ity and machinability. Next, the concepts of tool space H20849TSH20850, obstacle space H20849OSH20850, and machinable range H20849MRH20850 are introduced. A condition to determine the existence of machinability is also derived. The definitions provided in this section are used for the subsequent discussion in the remainder of this paper. Visibility:Apoint p on a surface SH20849pH33528SH20850 is visible by a light ray emanated from an external point q if pqH6023 suffices the condition of pqH6023H33370H20849SpH20850=H9021. Machinability:Apoint p on a surface SH20849pH33528SH20850 is machinable by a certain type and size of tool TH20849CL,H9251H20850 if pH33528TH20849CL,H9251H20850 and TH20849CL,H9251H20850H33370H20849SpH20850=H9021. TH20849CL,H9251H20850 represents the tool sur- face at the cutter location CL, approaching from the orien- tation H9251. By definition, machinability shares the same concept of acces- sibility with visibility, but differs in the sense that machinability takes into account the size and shape of the cutting tool instead of treating it simply as a line of light. Therefore, machinability can guarantee true accessibility, whereas visibility is only a necessary condition of machinability. Hence, the aggregate of orientations satisfying machinability is a subset of that satisfying visibility. In other words, machinability can guarantee visibility, but not vice versa. Unlike the expression of visibility in angular orientations, the bundle of which forms a cone, there are two parameters used to describe machinability. They are the cutter location and the ap- proaching orientation, if the type and size of a cutter are specified. Machinability with respect to an approaching orientation H9251 exists only if there is a cutter location that allows the cutting tool to approach and touch the point p without intersecting any other part surface. Similar to the concept of the visibility of a feature, the machin- ability of a feature H20849a line, a curve, or a patch of surface that is 456 / Vol. 128, MAY 2006 H20849PMH20850 of a feature can also be defined in addition to the concept of complete machinability H20849CMH20850. Partial Machinability: A feature is partially machinable along an orientation H9251 if there exists at least one point on that feature such that no cutter location CL exists for it to suffice the condition of pH33528TH20849CL,H9251H20850 and TH20849CL,H9251H20850H33370H20849S pH20850=H9021. Complete Machinability: A feature is completely machin- able along an orientation H9251 if for each point on that feature at least one cutter location CL can be found to guarantee the condition of pH33528TH20849CL,H9251H20850 and TH20849CL,H9251H20850H33370H20849SpH20850=H9021. Note that Complete Machinability may exist for either a point or a feature, whereas partial machinability exists only for a fea- ture, because a point can only be said to be either machinable or nonmachinable. If machinability exists with respect to an approaching orienta- tion H9251, the number of feasible cutter locations CLs may vary with different points on a surface. Points with more feasible CLs trans- lates to easier machining because the more possible CLs provide more options for tool-path and setup planning. The need to mea- sure the space of cutter locations leads to the concept of tool space. Tool Space: The aggregate of all feasible cutter locations to cut a point p from an orientation H9251 forms a region called tool space, written as TSH20849p,H9251H20850=H20853CL:p H33528TH20849CL,H9251H20850 and TH20849CL,H9251H20850H33370H20849SpH20850=H9021H20854. Tool space of a feature F is the union of the tool space of every point belonging to F; that is, TSH20849FH20850=H20853H33371TSH20849p,H9251H20850:pH33528FH20854. A tool space reaches its maximum value maximum tool space H20849MTSH20850 when there is no obstacle around the geometric entity. Here, we consider the entire part surface except the portion under consider- ation to be obstacles. Thus, the corresponding space for obstacles is defined as obstacle space. Obstacle Space: The aggregate of all unfeasible cutter loca- tions with respect to an orientation H9251 due to the existence of an obstacle i H20849ObiH20850 is called the obstacle space of obstacle i, written as OSH20849i,H9251H20850=H20853CL:TH20849CL,H9251H20850H33370ObiHS11005H9021H20854. The cutter cannot enter the domain of obstacle space because it will gouge into the obstacle. Tool space can be computed by subtracting all the obstacle spaces from maximum tool space. TS= MTS H20858 i OS H208491H20850 If the computed tool space using Eq. H208491H20850 is not empty, then machinability exists; otherwise, the geometric entity is nonma- chinable. The machinability analysis method presented in this pa- per is based on Eq. H208491H20850. Tool space is actually a measure of ma- chinability since it tells the existence of machinability and the magnitude of machinability, if it exists. Once the tool space is determined, the machinable range result- ing from it can be obtained. Machinable Range: The maximum machinable portion of a feature given the tool space is c
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