K09-轉向器殼體鉆孔夾具設計

資源目錄里展示的全都有，所見即所得。下載后全都有,請放心下載。原稿可自行編輯修改=【QQ：401339828 或11970985 有疑問可加】 轉向器殼體鉆孔夾具設計 摘 要 方向盤也被稱為轉向，轉向器，轉向系統(tǒng)，這是最重要的部分。它的主要作用是增加傳遞到轉向力，并在沿垂直于輸送臂的變化的轉向力。該結構的轉向形式可分為幾種類型。歷史上曾有過許多形式的轉向，現在比較常用的齒輪齒條，蝸桿曲柄指銷式，循環(huán)球-齒條齒扇式，循環(huán)球式曲柄手指，蝸輪式等。 本文轉向器殼體鉆井工藝和夾具設計。分水器外殼的孔中，形狀精度和位置精度要求的尺寸精度非常高，并且反過來殼體相交的重合氣缸布置成當在組合處理中，需要更準確和合理定位的殼體。并逐漸整個殼體的部件的固定和準確定位，實現了鉆孔的定位精度所要求的定位精度。 關鍵詞：轉向器 殼體 定位精度 夾具設計 Steering shell drilling fixture design Summary Steering is also called steering system, steering system, which is the most important part of the steering. Its role is to: increase the propagation direction of the steering wheel to change the power transmission and power steering linkage. Form of the steering structure can be divided into several types. Historically, there have been many forms of steering, there are currently more commonly used rack and pinion, worm crank the pin, recirculating ball - Fan-rack gear, recirculating ball crank pin and worm-type and so on. The main purpose of this system is to study the recirculating ball steering gear. This article discusses the recirculating ball steering gear housing bore and fixture design. Steering shell hole dimensional accuracy, shape accuracy and location accuracy requirements are very high, and the shell is a combination of two overlapping cross cylinder, and the arrangement process, the need for housing is more accurate, reasonable position. The housing member and the step of the overall behavior of the exact positioning, positioning accuracy of the correct positioning step to achieve the desired accuracy of drilling. Keywords：steering gear case positioning accuracy fixture design目錄 目錄 3 第一章 緒論 4 1.1 夾具的工作原理 4 1.2夾具的分類 4 1.3機床夾具的發(fā)展趨勢 4 1.4 本章小結 5 第二章 轉向器殼體鉆夾具的設計選擇 5 2.1 轉向器殼體的分析 6 2.2 機床的選擇 6 2.3 鉆床夾具的選擇 7 2.4 選擇鉆模板 7 2.5 鉆套的選擇 8 2.6 鉆套導引孔尺寸和公差的確定 9 2.7 鉆套高度選擇和鉆套與工件距離 9 第三章 工件在夾具中的定位 10 3.1 工件定位的基本原理 10 3.2 確定定位方案 10 3.3 定位元件的選擇與設計 11 4.4 導向元件的選擇 12 第四章 定位誤差的分析與計算 14 4.1 定位誤差 14 4.2 定位誤差的組成及計算方法 14 第五章 工件的夾緊 15 5.2 夾緊力的計算 15 參考文獻 17 致謝 18 第一章 緒論 1.1 夾具的工作原理 1 工件加工對準夾具的準確位置。它是由位于相應的面部表面與夾具接觸工件的定位元件的定位，有或取向來實現。 2 夾具在機床上應確保適當和準確的位置和方向固定結構，并確保相對于夾具和機床連接表面之間，從而確保相對夾具表面切割機移動到的面部的準確位置的工件的定位元件形成一個精確的表面幾何形狀，它達到了面向定位基準線所需的各等精密加工作業(yè)時的位置。 3 使刀具定位元件相關的確切位置，從而確保加工的工件定位基準位置大小的表面上的刀具相對定位面的調整。 1.2夾具的分類 根據不同類型的機床，夾具和固定裝置可分為車床夾具，銑床夾具，鉆夾具。通過不同的電源裝置采用，可分為手動夾具，氣動夾具等。 1.3機床夾具的發(fā)展趨勢 1．高精確度 與加工精度的提高，為了降低定位誤差，提高加工精度，制造精密的夾具苛求。 ± 5μm的精密定位夾具高音調的準確性，夾具支撐面達到0.01mm/300mm ，高平行度0.01mm/500mm 。德國demmeler （戴美樂）制造的長4米，寬2米的孔系列組合焊接夾具平臺， 5μm以下，它的高錯誤的定位是± 0.03毫米􀌔平行度和垂直度老虎鉗鉗安裝重復精度高達± 5μm的：瑞士EROWA重復柔性夾具定位精度可達2 ? 5μm的。精密夾具及固定裝置已提高到微米級，世界知名的夾具制造公司都是精密機械制造企業(yè)。事實上，為了滿足不同行業(yè)和經濟發(fā)展的需要，與文件夾不同型號和不同檔次的精度標準供選擇。 2高效 為了提高機器的生產效率。雙面，四片夾緊裝置和越來越多的產品。為了減少作業(yè)的安裝時間，各種自動定心夾緊臺鉗，杠桿夾緊，凸輪夾緊，氣動和液壓夾緊，以便快速夾緊功能前移。新的電控永磁夾具，加緊和只有1到2秒松開工件，夾具結構簡化為多臺機器，多方位，多部分的過程創(chuàng)造了條件。為了縮短機器上安裝和調整夾具的時間，瑞典3R夾具在短短一分鐘內完成安裝和校準電火花加工夾具。一分鐘之內，美國杰根斯（詹金斯）的球鎖裝夾系統(tǒng)將能夠找到并鎖定在機床工作臺上的夾具，球鎖裝夾系統(tǒng)用于柔性生產線更換夾具，起到停機時間提高生產效率的效果。 3模塊，所述組合 組合夾具元件是一個組合的基礎。省工，省時􀌑物質，能量，體現在創(chuàng)新的夾具系統(tǒng)中先進的。模擬演練切割工藝，既為用戶提供正確，合理的固定裝置及零部件配套項目，也是積累經驗，了解市場需求，不斷改進和完善夾具系統(tǒng)。 4 適用 ，經濟 夾具的通用性直接影響經濟。模塊化，組合夾具系統(tǒng)，一次性投資比較大，只有夾具系統(tǒng)的可重構性，可重構性和可擴展性的特點，以及應用范圍廣，通用性好，夾具利用率，更快的投資回報率，以反映經濟性好。強大的功能元素，使得夾具通用性好，簡潔的組件，配套成本低，經濟實用的應用程序具有推廣價值。 1.4 本章小結 本章的重點是夾具及固定裝置的制造機器，裝置及工作原理的作用及其發(fā)展趨勢的份額的重要作用。 第二章 轉向器殼體鉆夾具的設計選擇 2.1 轉向器殼體的分析 為了安裝需要鉆孔在所述殼體的4 Φ13 HFC方向側的表面上。下面工件。由于沒有現成的裝置可用，這樣流程來設計專用夾具。 2.2 機床的選擇 根據所須加工孔的，四孔的φ13基本尺寸。該機有三種可用的機床，數據如下： 型 號 最大鉆削直徑 主軸端面至工作臺最大距離 工作臺面積 主 軸 孔莫氏錐度號 最大行 程 轉 速 Z518 18 600 350×350 2 145 330-3040 ZQ4015 15 475 250×300 2 100 480-4100 Z535 35 750 450×500 4 225 68-1100 考慮到裝卸和拆卸，和表面積通過對各方面工件的比較，決定采用Z535立式鉆床。 2.3 鉆床夾具的選擇 許多類型的鉆孔夾具，可根據孔的分布可以被加工成： a 固定式鉆模： 在使用過程中，例如一夾具，固定在鉆探工作表面，但一般只用于垂直鉆孔加工時間。 b 回轉式鉆模： 用于處理分布式對在工件上的同一圓周上的相同或平行的孔的徑向孔的周圍。 c 翻轉式鉆模： 沒有這樣的夾具軸和索引方法。在此過程中需要使用一個手翻轉的?？字械闹魈幚淼男×慵讉€方向分布。 d 蓋板式鉆模： 這樣的夾具沒有特定的文件夾中，除了鉆孔模板鉆套，以及所述定位元件和夾緊裝置。在加工過程中，鉆模板為掩護覆蓋同一工件上。 e 滑柱式鉆模： 這是一種常見的可調夾具與升降鉆模板。 根據工件的特殊結構，決定采用蓋板夾具。它的特點是簡單，重量輕，易于清除切屑。對于大型和重型加工工件孔的大小，使用最合適的蓋板夾具。對于小批量，在那里鉆鉸鏈后，立即倒角，而其他進程，使用蓋鉆取模式也很方便。鉆模式每次需要從工件處理，比較麻煩，覆蓋時間，所以不適合大批量生產。 2.4 選擇鉆模板 鉆模板是供安裝鉆套用的。它有一定的剛度和強度，以防止套管和導向精度的影響，位置精度的變形。 常用的有以下幾種： a固定式鉆模板： 直接固定到所述上主體，并且是不可移動的。因此，為了獲得高的定位精度，但不是很方便的裝卸工作件。 b鉸鏈式鉆模板： 鉆孔模板及固定裝置鉸鏈連接。因為必須有在鉸鏈的間隙，所以該鉆孔加工精度的位置不是固定模更低。 c可卸式鉆模板： 當工件裝卸必須鉆去除模板，你應該可以采用可拆卸鉆模板。然而，由于處理鉆孔模板進行比較費時，而較少精密鉆孔的位置，所以一般使用時，其它類型的鉆孔模板是不容易的使用工件進行安裝。 d懸掛式鉆模板： 該鉆模板適合于大量生產的大量的鉆在相同的方向平行的孔，并與多軸驅動器或組合使用的垂直鉆孔機上。 應為工件結構有點獨特，要加工孔的位置精度不高，而且是小量生產。它決定采用可拆卸鉆模板。 2.5 鉆套的選擇 在鉆孔夾具通常是與鉆具對齊設置來實現，處理只需要對齊鉆頭夾持器，定位精度可以通過鉆孔工藝要求來實現。當然，也有增強的工具襯套剛度的影響。 因為這些孔的大小相同于在同一平面上處理不同的位置，它僅需要使用一個襯套。 鉆套的四種形式： a固定式鉆套： 一鉆套入固定式無肩，有肩。肩部主要用于鉆孔模板更薄要保持鉆頭導向套長度時。圓筒形軸套，以H7/r6或H7/n6壓力直接與此特定鉆頭或鉆模板集的缺點，該文件夾是不容易的更換磨損，它主要用于生產小批量加工鉆孔夾具或螺距和球場高精度小孔。為了防止切屑進入鉆孔設置鉆頭套筒的上端和下端應稍突出鉆孔模板為宜，通常不大于鉆孔模板更小。。 b可換鉆套： 可互換的襯套的實際功能和一個固定的軸襯，如在較大數量時，它可以被磨損后立即更換。避免穿鉆模板，鉆套不直接安裝在鉆模板或一個特定的文件夾但H6/G5 H7/G6或與襯套孔，具有防旋轉螺釘以防止摩擦處理當用工具解除工具，芯片和鉆孔的鉆套護套產生旋轉作用或回縮，并夾在襯套或鉆模板與特定的使用H7/n6或H7/r6 。 c 快換鉆套： 快速變化的位持有人受到相同的孔中使用的多個加工步驟。因為在這個過程中，這反過來需要更換，取下鉆套，以適應不同的切削工具的需求，宜采用快換鉆套。 d 特殊鉆套： 根據在順序的具體情況而設計，以補充組標準鉆頭性能不足。 通過比較，結合工件結構，決定采用固定鉆套的A型無肩鉆套。（數量為四個） 2.6 鉆套導引孔尺寸和公差的確定 設置的選擇標準鉆孔結構時，引導襯套孔的尺寸和公差需要根據以下原則確定： 1）導套基本尺寸鉆孔直徑應等于最大極限尺寸指南工具，以防止卡住而死亡 2）并與導向孔刀具的鉆頭套筒，軸應根據選擇系統(tǒng)中，因為這些工具的結構和尺寸已經標準化。 3）刀具和導向套筒之間的鉆孔應確保有一定的配合間隙，以防止堵塞。根據所選刀具的類型和精度要求導孔公差引導，鉆孔和擴孔選F7，F8 ;原油相比G7選舉;精度被選擇比G6 。 4）標準鉆孔的最大尺寸被處理的基本尺寸，鉆導向孔的基本尺寸和孔的加工公差的相同的基本尺寸取F7 。 5）如果工具不開機的切削部分，但與導柱部分，可以按與H7/f7 ， H7/g6 ，或H6/g5選擇相應的孔基礎。 故鉆套導引孔以便在相同的一套基本的基本尺寸和孔的加工公差的大小取F7。 2.7 鉆套高度選擇和鉆套與工件距離 1．鉆套高度 是由鉆頭套筒的精度，工件材料，孔的加工精度，工具壽命，其表面形狀因子的高度確定。的± 0.25毫米間距或自由公差尺寸精度鉆，鉆套的高度取H=（1.5～2.5）d。鉆套內徑采用基軸制F8的公差。所以H=（1.5～2.5）d=（1.5～2.5）×13=19.5～32.5mm 加工IT6～IT7級精度，孔距在12mm以上的孔或加工工件孔距精度要求在±0.10～±0.15mm時，鉆套的高度取H=（2.5～3.5）d鉆套內徑采用基軸制G7的公差。 H=（2.5～2）d=（2.5～3.5）×13=32.5～45.5mm 由于該零件加工孔精度不怎么高，故鉆套高度取27mm. 2．鉆套與工件的距離 工件和鉆頭套筒留有一定距離h之間，如果h過大傾斜量增加，使得鉆頭夾持器是不是一個很好的指導。 h過小，則切屑排出困難，不僅提高了工件的表面粗糙度，鉆頭有時會斷裂。 H值可按下面經驗公式選?。? 加工鑄鐵、黃銅時，h=（0.3～0.7）d； 加工鋼件時，h=（0.7～1.5）d； 由于工件是鑄鐵，故取 h=（0.3～0.7）d=（0.3～0.7）×13=3.9～9.1mm取7.5mm。 第三章 工件在夾具中的定位 3.1 工件定位的基本原理 1．六點定位原理 工件定位性質是使工件占據在夾具中一個確定的位置。這個位置可以通過將支持相應的限制，獲得自由的程度來確定。在空間中的對象有六個自由度笛卡爾坐標。這種自由沿三個相互垂直的軸線的運動，以及圍繞旋轉自由度的三個軸 2．完全定位與不完全定位 如果僅基于所述臺階部的自由限制了加工要求，而另一度，而不會限制所述工件的自由而沒有占據一個唯一的位置確定，但是這個步驟不影響加工要求不完全清楚，此時定位。應該使用或不完全定位完全定位主要是由加工要求的方法測定。 3．欠定位與過定位 由于定位裝置的程度的工件的定位限制自由的實際數目，該過程是小于的自由度，通過限制所述處理要求是必要的數目。因此，由于結果的定位將導致自由和應該限制限制是并非不合理現象，這并不能保證該程序規(guī)定的處理要求。定位兩個或多個點的支持與限制的自由反復，這種現象稱為過度重復定位的定位。 4．定位支承點的配置 在六個定位，定位的支持點的配置，定位精度和穩(wěn)定性很大。 3.2 確定定位方案 根據上述被處理部和各個表面的特殊結構。具體方案如下： 工件應該限制的自由：X，移動在Y方向上的自由， X，Y， Z方向的轉動自由度 2） a以已加工的底面為基準面，限制 X ，Y方向的轉動自由度，Z方向的移動自由度。 b 以中間孔套入一根長芯軸，限制X， Y方向的轉動和移動自由度。 c 以后面的已加工的孔為基準套入一定位軸，限制Z 方向的自由度。 所以出現了重復定位的情況。但由于是采用已加工面為基準，所以對該定位方案是合理的。 3.3 定位元件的選擇與設計 工件在夾具中位置的確定，主要是通過各種類型的定位元件實現的。一般的定位元件有： 1） 平面定位元件：固定支承、可調支承、自位支承、輔助支承。 固定支承：支承點的位置固定不變的定位元件。如各種固定支承釘。 可調支承：支承點的位置可調節(jié)的定位元件。如可擰動的螺釘。 自位支承：支承本身在定位過程中所處的位置，隨工件定位基準面的變化而自動與之適應，其作用相當于一個固定支承，只限制一個自由度。由于增加了與定位基準面接觸的點數，故可提高工件的安裝剛性和穩(wěn)定性。適用于工件以粗基準定位或剛性不足的場合。 輔助支承：這類支承只起提高工件支承剛性或起輔助作用的定位元件而不起定位作用。 2） 圓孔表面定位元件 這類定位元件常用于圓孔表面。一般定位元件有：定位銷、剛性心軸、錐度心軸等。 3） 外圓表面定位元件 這類定位元件常用于外圓表面定位。一般有：定位套、支承板、V型塊等。 定位套對工件外圓表面主要實現定心定位；支承板實現對外圓表面的支承定位；V型塊則實現對外圓表面的定心對中定位。 4 ）錐面定位元件 主要用于加工軸類零件或某些要求精度定心的零件時，以工件上的錐孔作為定位基準?？商岣吖ぜS向的定位精度。 根據工件在工件孔，類似于懸臂的向下的力，鉆頭的一部分，扭轉力矩和重力的力和作用時引起的鉆孔的工件的平面結構的特殊性。工件通過重力下垂的作用，而使從所述定位元件將工件定位基準。同時，也使工件的振動，從而導致損害的工具，最終影響加工質量。根據這一特點，決定采用輔助支持。在工件的下部可能需要的孔的輔助支持。在第一預定位置，然后在主重新定位和所有的接觸元件的準確定位的夾緊力的作用下。所述支撐構件是球形的支柱?？紤]四個孔被加工，并且孔的位置不是對稱的，該分布是大的，所以使用兩個這樣的柱子。 這樣的支柱，具體如上圖。 對于工件的后部，由于采用了一個定位軸，所以要保證定位軸的定位。決定一端用定位螺釘，一端用壓緊螺釘。 4.4 導向元件的選擇 行動導向元件被用來確定刀具與工件的相對位置時，刀具導向作用正確播放。時也定位元件都可以使用。這些元素包括各種鉆模板，鉆套，鉸鏈蓋和引導支持等 1）鉆模板 我們已經選擇了可拆卸鉆模板。但是普通的可拆卸鉆模板還不能滿足我們的加工孔的要求，所以要另外設計。因為孔是兩套并行處理孔不對稱的。的分析表明，它們與中間孔之間的垂直連接成164°角。為了確保加工的精度，鉆模板可以被設計成三角形花鍵連接，花鍵齒的中心線164 °角，只是垂直的設計寬度的形式。花鍵與拉削或鉆孔加工，熱處理后的方法用于提高定心面的磨削精度。三角形與外花鍵齒銑機，熱處理后的磨削方法也可用于改善定心表面的精度和側翼，具體設計如下： 三角花鍵 根據Dg=32 查表6-74內花鍵弧齒槽寬和外花鍵弧齒厚偏差取m=2 齒數：z=14 模數：m=2 分度圓：df=dg-2(0.6+ξ)m=32-2(0.6+0.1)×2=29.2mm 齒頂圓直徑：dd= df+2(0.4+ξ)m=29.2+2(0.4+0.1)m=31.2mm 齒根圓直徑: dg=df -2(0.6-ξ)m=29.2-2(0.6-0.1)×2=26.6mm 公稱圓：D=df +2×(0.4+ξ)m=29.2+2×（0.4+0.1）×2=31.2mm 內花鍵齒根圓弧起始點直徑：dq=(z+1.1)m=(14+1.1)2=30.2mm 內花鍵齒槽寬：s=(π/2+2ξtanα)=(3.14/2+tan45°×2×0.1)=3.54 內花鍵齒槽角：β=90°-203°/z=90°-203°/14=76.5° 外花鍵基圓:dj=df+2×(0.4+ξ)m=29.2+2×(0.4+0.1)×2=31.2mm 內花鍵齒根高：h"1=(0.6+ξ)× m=(0.6+0.1)×2=1.4 內花鍵齒頂高：h′1=(0.4-ξ)×m=(0.4-0.1)×2=0.6 外花鍵齒根高：h"=(0.4+ξ)m=(0.4+0.1)×2=1 外花鍵齒頂高：h′=(0.6-ξ)m=(0.6-0.1)×2=1 內花鍵齒頂圓直徑：Dg=df+2×(0.6+ξ)m=29.2+2(0.6+0.1)×2= 32 分度圓周節(jié)：t=πm=3.14×2=6.28 內外表面光潔度的粗糙度必須在3.2～1.6之間。 而芯軸也就設計如下圖： 第四章 定位誤差的分析與計算 4.1 定位誤差 定位誤差是由于一個過程取向所造成的步長（通常指的是加工表面的距離的步長的基礎上），或者處理錯誤的位置的要求是不允許的。的定位方案，通過分析其可能的定位誤差，只要大于約1/3至1/5的工件的公差的尺寸或位置減計算。這個取向的程序，通常被認為是能滿足精密加工工藝的要求。 工件在夾具中的位置是由定位件確定的，一旦工件的定位面時，與定位部件或夾具的整體接觸，該位置將決定工件。然而，對于一個數的工件，由于每個工件的表面是介于約彼此在尺寸和位置上的差在容許范圍內。是鉗和相應的定位元件本身之間的大小和位置公差。因此，工件的定位雖然，被定位于特定的表面的每個元素將具有自己的位置變動量，造成了步長大小，并且處理錯誤的位置的要求。 4.2 定位誤差的組成及計算方法 定位誤差是加工調整法，該法只允許因定位所造成的進程大小或位置的要求，盡最大可能的變化過程中工件的數量。該定位誤差由基準誤差占主導地位，并引用沒有重合誤差兩部分組成。因此，在夾具的設計中，定位方案的任何一個，由多個定位工件，直接計算的參考步驟的最大波動范圍的兩個極限位置，該定位誤差為定位程序。 孔的工件的最大直徑和當所述定位銷O1O2, O1相對于上述圓筒狀工件和工件的尺寸，最小步長Hmin的最高位置時的相對位置OO2針的定位銷的最低條件沿O2工件的幾何形狀，以最大升力的底部位置的上述圓筒狀工件的最大尺寸下，定位誤差的過程，此時，我們可以看到的H在工件定位銷孔的直徑的大小和最大的最小條件的直徑中，當相對于定位銷O1O2 O1在最高位置與上述圓筒狀工件小時的尺寸工件時，最小步長Hmin的，當相對于定位銷OO2向下沿O2外側的工件的底部位置的工件圓的最大大小，則處理大小為最大揚程時，定位誤差在這個時間步長大小H被稱為： δ定位 =A1A2=Hmax–Hmin=O1O2+1/2d-1/2(d-Td)=O1O2 +1/2Td 根據定位誤差產生的原因也可按定位誤差的組成進行計算： δ定位=δ位置+δ不重=O1O2 +1/2Td 在工件的裝夾配合當中，由于芯軸與工件采用的是H7/k6過渡配合，故認為O1O2基本為0。所以： δ定位=0.5Td 即為芯軸公差的一半。 第五章 工件的夾緊 5.2 夾緊力的計算 1）夾緊力的方向 由于在整個加工過程是以工件底面為準，鉆模板壓在上面，所以上面可以用螺母直接夾緊。 根據材料的磨損和耐用度標準8-37位查表孔尺寸： 后刀面最大磨損極限：0.5～0.8mm，T=3600 刀具切削速度： V=27.91/51.62=0.52 m/s 表10-3中鉆切削速度的計算公式： Cv=14.7 Zv=0.25 Yv=0.55 m=0.125 f=0.3mm/r 查表10-4 鉆削時軸向力，扭距和功率的計算公式 F=9.81×42.7×13×0.3×1=3471.57N M=9.81×0.021×13×0.3×1 =13.29N·m Pm=2Mv/d=2×13.29/13 =2.04k N F =Fw，簡化FW朝向中心,芯軸的軸向力Fw和旋轉力矩T ,當鉆削在如圖的孔時力矩最大,故計算這一個便可: T =FwL=3471.5×157=545000N·mm 預緊力: Fp= kuF/uc=1.2×3471.57/0.15=27800N 根據芯軸許用應力驗算公式芯軸: 表11-6,螺釘,螺柱和螺母的力學性能等級 = [σ]=σs/s=480/1.5=320 MP D=4×1.3×2.78×10000/3.14×320=12mm 考慮到安全性螺母M14。由于橫向負荷，在這里不作計算。 參考文獻 1.機床夾具零部件 第一機械工業(yè)部機床研究所 1966 2.吳克堅主編 機械原理 高等教育出版社 1990 3.吳宗澤主編 機械設計高等教育出版社 1991 4.吳可想主編 機械設計及其自動化 2008 5.李明亞主編 機床夾具設計 1993 6.李偉主編 機械設計手冊 1993 7.機床夾具設計手冊 上?？茖W技術出版社 1990 8.機床夾具 上?？茖W技術出版社 1991 9.機床夾具及良具設計 白海清主編 2013 致謝 也許是時間的流逝是客觀的，但時光流逝純粹是主觀感覺。當我終于從考公務員，找工作，畢業(yè)設計釋放的壓力之下解脫出來，長嘆一聲，我突然明白了，原來已經在過去的四年里，到了告別的時候。一念至此，居然在恍惚中，所謂的流年，想必就是這么憂郁。但之后的失落感，總是有話說。大學四年，生活其實很簡單，但一次又一次的一些閱讀，寫作和考試。如果生命作為秀場的這個單調的循環(huán)，我只是提供了一個安靜的演員。雖然沒有什么精彩的臺詞，但這個詞是幕即將告一段落這個時期。但不管有多么的差勁的演員，不管有多少觀眾觀眾，哪怕只是說給自己聽，在他的謝幕也永遠感謝一些人，這些人幫助他走上舞臺，成功或不那么成功的表現。我在這里首先要感謝我的論文指導教授 – 樊十全老師。從本論文的開題，數據查詢，修改定稿沒有他的努力，不知道會以何種面目出現。我很榮幸有這樣的老師，他是值得我感敬和尊重。我感謝工學院所有的學生和精彩的度過大學四年的人生的2010農業(yè)機械化及其自動化類的同學。感謝學院的所有老師，你讓我終身難忘。感謝所有關心，鼓勵和支持我的家人，親戚和朋友。 18 Robotics and Computer-Integrated Manufacturing 21 (2005) 368378Locating completeness evaluation and revision in fixture planH. Song?, Y. RongCAM Lab, Department of Mechanical Engineering, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609, USAReceived 14 September 2004; received in revised form 9 November 2004; accepted 10 November 2004AbstractGeometry constraint is one of the most important considerations in fixture design. Analytical formulation of deterministiclocation has been well developed. However, how to analyze and revise a non-deterministic locating scheme during the process ofactual fixture design practice has not been thoroughly studied. In this paper, a methodology to characterize fixturing systemsgeometry constraint status with focus on under-constraint is proposed. An under-constraint status, if it exists, can be recognizedwith given locating scheme. All un-constrained motions of a workpiece in an under-constraint status can be automatically identified.This assists the designer to improve deficit locating scheme and provides guidelines for revision to eventually achieve deterministiclocating.r 2005 Elsevier Ltd. All rights reserved.Keywords: Fixture design; Geometry constraint; Deterministic locating; Under-constrained; Over-constrained1. IntroductionA fixture is a mechanism used in manufacturing operations to hold a workpiece firmly in position. Being a crucialstep in process planning for machining parts, fixture design needs to ensure the positional accuracy and dimensionalaccuracy of a workpiece. In general, 3-2-1 principle is the most widely used guiding principle for developing a locationscheme. V-block and pin-hole locating principles are also commonly used.A location scheme for a machining fixture must satisfy a number of requirements. The most basic requirement is thatit must provide deterministic location for the workpiece 1. This notion states that a locator scheme producesdeterministic location when the workpiece cannot move without losing contact with at least one locator. This has beenone of the most fundamental guidelines for fixture design and studied by many researchers. Concerning geometryconstraint status, a workpiece under any locating scheme falls into one of the following three categories:1. Well-constrained (deterministic): The workpiece is mated at a unique position when six locators are made to contactthe workpiece surface.2. Under-constrained: The six degrees of freedom of workpiece are not fully constrained.3. Over-constrained: The six degrees of freedom of workpiece are constrained by more than six locators.In 1985, Asada and By 1 proposed full rank Jacobian matrix of constraint equations as a criterion and formed thebasis of analytical investigations for deterministic locating that followed. Chou et al. 2 formulated the deterministiclocating problem using screw theory in 1989. It is concluded that the locating wrenches matrix needs to be full rank toachieve deterministic location. This method has been adopted by numerous studies as well. Wang et al. 3 consideredARTICLE IN PRESS front matter r 2005 Elsevier Ltd. All rights reserved.doi:10.1016/j.rcim.2004.11.012?Corresponding author. Tel.: +15088316092; fax: +15088316412.E-mail address: hsongwpi.edu (H. Song).locatorworkpiece contact area effects instead of applying point contact. They introduced a contact matrix andpointed out that two contact bodies should not have equal but opposite curvature at contacting point. Carlson 4suggested that a linear approximation may not be sufficient for some applications such as non-prismatic surfaces ornon-small relative errors. He proposed a second-order Taylor expansion which also takes locator error interaction intoaccount. Marin and Ferreira 5 applied Chous formulation on 3-2-1 location and formulated several easy-to-followplanning rules. Despite the numerous analytical studies on deterministic location, less attention was paid to analyzenon-deterministic location.In the Asada and Bys formulation, they assumed frictionless and point contact between fixturing elements andworkpiece. The desired location is q*, at which a workpiece is to be positioned and piecewisely differentiable surfacefunction is gi(as shown in Fig. 1).The surface function is defined as giq? 0: To be deterministic, there should be a unique solution for the followingequation set for all locators.giq 0;i 1;2;.;n,(1)where n is the number of locators and q x0;y0;z0;y0;f0;c0? represents the position and orientation of theworkpiece.Only considering the vicinity of desired location q?; where q q? Dq; Asada and By showed thatgiq giq? hiDq,(2)where hiis the Jacobian matrix of geometry functions, as shown by the matrix in Eq. (3). The deterministic locatingrequirement can be satisfied if the Jacobian matrix has full rank, which makes the Eq. (2) to have only one solutionq q?:rankqg1qx0qg1qy0qg1qz0qg1qy0qg1qf0qg1qc0:qgiqx0qgiqy0qgiqz0qgiqy0qgiqf0qgiqc0:qgnqx0qgnqy0qgnqz0qgnqy0qgnqf0qgnqc026666666664377777777758:9=; 6.(3)Upon given a 3-2-1 locating scheme, the rank of a Jacobian matrix for constraint equations tells the constraint statusas shown in Table 1. If the rank is less than six, the workpiece is under-constrained, i.e., there exists at least one freemotion of the workpiece that is not constrained by locators. If the matrix has full rank but the locating scheme hasmore than six locators, the workpiece is over-constrained, which indicates there exists at least one locator such that itcan be removed without affecting the geometry constrain status of the workpiece.For locating a model other than 3-2-1, datum frame can be established to extract equivalent locating points. Hu 6has developed a systematic approach for this purpose. Hence, this criterion can be applied to all locating schemes.ARTICLE IN PRESSX Y Z O X Y Z O (x0,y0,z0) gi UCS WCS Workpiece Fig. 1. Fixturing system model.H. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378369Kang et al. 7 followed these methods and implemented them to develop a geometry constraint analysis module intheir automated computer-aided fixture design verification system. Their CAFDV system can calculate the Jacobianmatrix and its rank to determine locating completeness. It can also analyze the workpiece displacement and sensitivityto locating error.Xiong et al. 8 presented an approach to check the rank of locating matrix WL(see Appendix). They also intro-duced left/right generalized inverse of the locating matrix to analyze the geometric errors of workpiece. It hasbeen shown that the position and orientation errors DX of the workpiece and the position errors Dr of locators arerelated as follows:Well-constrained :DX WLDr,(4)Over-constrained :DX WTLWL?1WTLDr,(5)Under-constrained :DX WTLWLWTL?1Dr I6?6? WTLWLWTL?1WLl,(6)where l is an arbitrary vector.They further introduced several indexes derived from those matrixes to evaluate locator configurations, followed byoptimization through constrained nonlinear programming. Their analytical study, however, does not concern therevision of non-deterministic locating. Currently, there is no systematic study on how to deal with a fixture design thatfailed to provide deterministic location.2. Locating completeness evaluationIf deterministic location is not achieved by designed fixturing system, it is as important for designers to knowwhat the constraint status is and how to improve the design. If the fixturing system is over-constrained, informa-tion about the unnecessary locators is desired. While under-constrained occurs, the knowledge about all the un-constrained motions of a workpiece may guide designers to select additional locators and/or revise the locatingscheme more efficiently. A general strategy to characterize geometry constraint status of a locating scheme is describedin Fig. 2.In this paper, the rank of locating matrix is exerted to evaluate geometry constraint status (see Appendixfor derivation of locating matrix). The deterministic locating requires six locators that provide full rank locatingmatrix WL:As shown in Fig. 3, for given locator number n; locating normal vector ai;bi;ci? and locating position xi;yi;zi? foreach locator, i 1;2;.;n; the n ? 6 locating matrix can be determined as follows:WLa1b1c1c1y1? b1z1a1z1? c1x1b1x1? a1y1:aibiciciyi? biziaizi? cixibixi? aiyi:anbncncnyn? bnznanzn? cnxnbnxn? anyn2666666437777775.(7)When rankWL 6 and n 6; the workpiece is well-constrained.When rankWL 6 and n46; the workpiece is over-constrained. This means there are n ? 6 unnecessary locatorsin the locating scheme. The workpiece will be well-constrained without the presence of those n ? 6 locators. Themathematical representation for this status is that there are n ? 6 row vectors in locating matrix that can be expressedas linear combinations of the other six row vectors. The locators corresponding to that six row vectors consist oneARTICLE IN PRESSTable 1RankNumber of locatorsStatuso 6Under-constrained 6 6Well-constrained 646Over-constrainedH. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378370locating scheme that provides deterministic location. The developed algorithm uses the following approach todetermine the unnecessary locators:1. Find all the combination of n ? 6 locators.2. For each combination, remove that n ? 6 locators from locating scheme.3. Recalculate the rank of locating matrix for the left six locators.4. If the rank remains unchanged, the removed n ? 6 locators are responsible for over-constrained status.This method may yield multi-solutions and require designer to determine which set of unnecessary locators shouldbe removed for the best locating performance.When rankWLo6; the workpiece is under-constrained.3. Algorithm development and implementationThe algorithm to be developed here will dedicate to provide information on un-constrained motions of theworkpiece in under-constrained status. Suppose there are n locators, the relationship between a workpieces position/ARTICLE IN PRESSFig. 2. Geometry constraint status characterization.X Z Y (a1,b1,c1) 2,b2,c2) (x1,y1,z1) (x2,y2,z2) (ai,bi,ci) (xi,yi,zi) (aFig. 3. A simplified locating scheme.H. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378371orientation errors and locator errors can be expressed as follows:DX DxDyDzaxayaz2666666666437777777775w11:w1i:w1nw21:w2i:w2nw31:w3i:w3nw41:w4i:w4nw51:w5i:w5nw61:w6i:w6n2666666666437777777775?Dr1:Dri:Drn2666666437777775,(8)where Dx;Dy;Dz;ax;ay;azare displacement along x, y, z axis and rotation about x, y, z axis, respectively. Driisgeometric error of the ith locator. wijis defined by right generalized inverse of the locating matrix Wr WTLWLWTL?15.To identify all the un-constrained motions of the workpiece, V dxi;dyi;dzi;daxi;dayi;dazi? is introduced such thatV DX 0.(9)Since rankDXo6; there must exist non-zero V that satisfies Eq. (9). Each non-zero solution of V represents an un-constrained motion. Each term of V represents a component of that motion. For example, 0;0;0;3;0;0? says that therotation about x-axis is not constrained. 0;1;1;0;0;0? means that the workpiece can move along the direction given byvector 0;1;1?: There could be infinite solutions. The solution space, however, can be constructed by 6 ? rankWLbasic solutions. Following analysis is dedicated to find out the basic solutions.From Eqs. (8) and (9)VX dxDx dyDy dzDz daxDax dayDay dazDaz dxXni1w1iDri dyXni1w2iDri dzXni1w3iDri daxXni1w4iDri dayXni1w5iDri dazXni1w6iDriXni1Vw1i;w2i;w3i;w4i;w5i;w6i?TDri 0.10Eq. (10) holds for 8Driif and only if Eq. (11) is true for 8i1pipn:Vw1i;w2i;w3i;w4i;w5i;w6i?T 0.(11)Eq. (11) illustrates the dependency relationships among row vectors of Wr: In special cases, say, all w1jequal to zero,V has an obvious solution 1, 0, 0, 0, 0, 0, indicating displacement along the x-axis is not constrained. This is easy tounderstand because Dx 0 in this case, implying that the corresponding position error of the workpiece is notdependent of any locator errors. Hence, the associated motion is not constrained by locators. Moreover, a combinedmotion is not constrained if one of the elements in DX can be expressed as linear combination of other elements. Forinstance, 9w1ja0;w2ja0; w1j ?w2jfor 8j: In this scenario, the workpiece cannot move along x- or y-axis. However, itcan move along the diagonal line between x- and y-axis defined by vector 1, 1, 0.To find solutions for general cases, the following strategy was developed:1. Eliminate dependent row(s) from locating matrix. Let r rank WL; n number of locator. If ron; create a vectorin n ? r dimension space U u1:uj:un?rhi1pjpn ? r; 1pujpn: Select ujin the way that rankWL r still holds after setting all the terms of all the ujth row(s) equal to zero. Set r ? 6 modified locating matrixWLMa1b1c1c1y1? b1z1a1z1? c1x1b1x1? a1y1:aibiciciyi? biziaizi? cixibixi? aiyi:anbncncnyn? bnznanzn? cnxnbnxn? anyn2666666437777775r?6,where i 1;2;:;niauj:ARTICLE IN PRESSH. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 3683783722. Compute the 6 ? n right generalized inverse of the modified locating matrixWr WTLMWLMWTLM?1w11:w1i:w1rw21:w2i:w2rw31:w3i:w3rw41:w4i:w4rw51:w5i:w5rw61:w6i:w6r26666666664377777777756?r3. Trim Wrdown to a r ? rfull rank matrix Wrm: r rankWLo6: Construct a 6 ? r dimension vector Q q1:qj:q6?rhi1pjp6 ? r; 1pqjpn: Select qjin the way that rankWr r still holds after setting all theterms of all the qjth row(s) equal to zero. Set r ? r modified inverse matrixWrmw11:w1i:w1r:wl1:wli:wlr:w61:w6i:w6r26666664377777756?6,where l 1;2;:;6 laqj:4. Normalize the free motion space. Suppose V V1;V2;V3;V4;V5;V6? is one of the basic solutions of Eq. (10) withall six terms undetermined. Select a term qkfrom vector Q1pkp6 ? r: SetVqk ?1;Vqj 0 j 1;2;:;6 ? r;jak;(5. Calculated undetermined terms of V: V is also a solution of Eq. (11). The r undetermined terms can be found asfollows.v1:vs:v62666666437777775wqk1:wqki:wqkr2666666437777775?w11:w1i:w1r:wl1:wli:wlr:w61:w6i:w6r2666666437777775?1,where s 1;2;:;6saqj;saqk;l 1;2;:;6 laqj:6. Repeat step 4 (select another term from Q) and step 5 until all 6 ? r basic solutions have been determined.Based on this algorithm, a C+ program was developed to identify the under-constrained status and un-constrained motions.Example 1. In a surface grinding operation, a workpiece is located on a fixture system as shown in Fig. 4. The normalvector and position of each locator are as follows:L1:0, 0, 10, 1, 3, 00,L2:0, 0, 10, 3, 3, 00,L3:0, 0, 10, 2, 1, 00,L4:0, 1, 00, 3, 0, 20,L5:0, 1, 00, 1, 0, 20.Consequently, the locating matrix is determined.WL0013?100013?300011?20010?203010?2012666666437777775.ARTICLE IN PRESSH. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378373This locating system provides under-constrained positioning since rankWL 5o6: The program then calculatesthe right generalized inverse of the locating matrix.Wr000000:50:5?1?0:51:50:75?1:251:5000:250:25?0:5000:5?0:50000000:5?0:526666666643777777775.The first row is recognized as a dependent row because removal of this row does not affect rank of the matrix. Theother five rows are independent rows. A linear combination of the independent rows is found according therequirement in step 5 of the procedure for under-constrained status. The solution for this special case is obvious that allthe coefficients are zero. Hence, the un-constrained motion of workpiece can be determined as V ?1; 0; 0; 0; 0; 0?:This indicates that the workpiece can move along x direction. Based on this result, an additional locator should beemployed to constraint displacement of workpiece along x-axis.Example 2. Fig. 5 shows a knuckle with 3-2-1 locating system. The normal vector and position of each locator in thisinitial design are as follows:L1:0, 1, 00, 896, ?877, ?5150,L2:0, 1, 00, 1060, ?875, ?3780,L3:0, 1, 00, 1010, ?959, ?6120,L4:0.9955, ?0.0349, 0.0880, 977, ?902, ?6240,L5:0.9955, ?0.0349, 0.0880, 977, ?866, ?6240,L6:0.088, 0.017, ?0.9960, 1034, ?864, ?3590.The locating matrix of this configuration isWL010515:000:8960010378:001:0600010612:001:01000:9955?0:03490:0880?101:2445?707:26640:86380:9955?0:03490:0880?98:0728?707:26640:82800:08800:0170?0:9960866:6257998:24660:093626666666643777777775,rankWL 5o6 reveals that the workpiece is under-constrained. It is found that one of the first five rows can beremoved without varying the rank of locating matrix. Suppose the first row, i.e., locator L1is removed from WL; theARTICLE IN PRESSXZYL3L4L5L2L1Fig. 4. Under-constrained locating scheme.H. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378374modified locating matrix turns intoWLM010378:001:0600010612:001:01000:9955?0:03490:0880?101:2445?707:26640:86380:9955?0:03490:0880?98:0728?707:26640:82800:08800:0170?0:996866:6257998:24660:09362666666437777775.The right generalized inverse of the modified locating matrix isWr1:8768?1:8607?20:666521:37160:49953:0551?2:0551?32:444832:44480?1:09561:086212:0648?12:4764?0:2916?0:00440:00440:0061?0:006100:0025?0:00250:0065?0:00690:0007?0:00040:00040:0284?0:0284026666666643777777775.The program checked the dependent row and found every row is dependent on other five rows. Without losinggenerality, the first row is regarded as dependent row. The 5 ? 5 modified inverse matrix isWrm3:0551?2:0551?32:444832:44480?1:09561:086212:0648?12:4764?0:2916?0:00440:00440:0061?0:006100:0025?0:00250:0065?0:00690:0007?0:00040:00040:0284?0:028402666666437777775.The undetermined solution is V ?1; v2; v3; v4; v5; v6?:To calculate the five undetermined terms of V according to step 5,1:8768?1:8607?20:666521:37160:499526666666643777777775T?3:0551?2:0551?32:444832:44480?1:09561:086212:0648?12:4764?0:2916?0:00440:00440:0061?0:006100:0025?0:00250:0065?0:00690:0007?0:00040:00040:0284?0:0284026666666643777777775?1 0; ?1:713; ?0:0432; ?0:0706; 0:04?.Substituting this result into the undetermined solution yields V ?1;0; ?1:713; ?0:0432; ?0:0706; 0:04?ARTICLE IN PRESSFig. 5. Knuckle 610 (modified from real design).H. Song, Y. Rong / Robotics and Computer-Integrated Manufacturing 21 (2005) 368378375This vector represents a free motion defined by the combination of a displacement along ?1, 0, ?1.713 directioncombined and a rotation about ?0.0432, ?0.0706, 0.04. To revise this locating configuration, another locator shouldbe added to constrain this free motion of the workpiece, assuming locator L1was removed in step 1. The program canalso calculate the free motions of the workpiece if a locator other than L1was removed in step 1. This provides morerevision options for designer.4. SummaryDeterministic location is an important requirement for fixture locating scheme design. Analytical criterion fordeterministic status has been well established. To further study non-deterministic status, an algorithm for checking thegeometry constraint status has been developed. This algorithm can identify an under-constrained status and indicatethe un-constrained motions of workpiece. It can also recognize an over-constrained status and unnecessary locators.The output information can assist designer to analyze and improve an existing locating scheme.Appendix. Locating matrixConsider a general workpiece as shown in Fig. 6. Choose reference frame fWg fixed to the workpiece. Let fGg andfLig be the global frame and the ith locator frame fixed relative to it. We haveFiXw;Hw;rwi fiXli;Hli;rli,(12)where Xw2 3?1and Hw2 3?1(Xli2 3?1and Hli2 3?1) are the position and orientation of the workpiece(the ith locator) in the global frame fGg; rwi2 3?1(rli2 3?1) is the position of the ith contact point between theworkpiece and the ith locator in the workpiece frame fWg (the ith locator frame fLig).Assume that DXw2 3?1(DHw2 3?1) and Drwi2 3?1are the deviations of the position Xw2 3?1(orientationHw2 3?1) of the workpiece and the position of the ith contact point rwi2 3?1; respectively. Then we have the actualcontact on the wor