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1 緒論
機(jī)械手，英文名mechanical hand，是指模仿人手和臂的某些動(dòng)作和功能，用以按固定程序抓取、搬運(yùn)物件或操作工具的自動(dòng)操作裝置。
工業(yè)機(jī)械手即在工業(yè)生產(chǎn)中所使用的機(jī)械手，是一種可編程序的自動(dòng)機(jī)械手。它是在五十年代末出現(xiàn)，近年來(lái)迅速發(fā)展起來(lái)的重要的自動(dòng)化裝置，是實(shí)現(xiàn)冬夜自動(dòng)化的重要手段。目前，在各個(gè)生產(chǎn)領(lǐng)域，為了提高生產(chǎn)效率和產(chǎn)品質(zhì)量，實(shí)現(xiàn)安全生產(chǎn)，都采用了各種不同形式，不同功能的機(jī)械手。由于機(jī)械手的出現(xiàn)，在許多生產(chǎn)工藝中都代替了人工，使工業(yè)自動(dòng)化有了較大的發(fā)展，這不僅大大的提高了勞動(dòng)生產(chǎn)率，改善了勞動(dòng)條件，減輕了工人勞動(dòng)強(qiáng)度，而且使成批生產(chǎn)有了質(zhì)量技術(shù)的保證，就因?yàn)槿绱?，機(jī)械手的設(shè)計(jì)開(kāi)發(fā)成了目前工業(yè)技術(shù)的重要課題。
1.1 研究背景及發(fā)展現(xiàn)狀
機(jī)械手在工業(yè)生產(chǎn)中廣泛的應(yīng)用于機(jī)加工，鍛壓，鑄造，沖壓，焊接，裝配，噴漆，熱處理等各個(gè)行業(yè)，特別是在笨重，高溫有毒，放射性，多粉塵等惡劣危險(xiǎn)的勞動(dòng)環(huán)境中，機(jī)械手由于有顯著的優(yōu)點(diǎn)而備受重視。以下是機(jī)械手在工業(yè)中的幾種典型應(yīng)用:
1.在實(shí)現(xiàn)單機(jī)自動(dòng)化方面
1) 各類半自動(dòng)車床，有自動(dòng)加緊、進(jìn)刀，切削、退刀和松開(kāi)的功能，但仍需人工上下料。裝上機(jī)械手，可實(shí)現(xiàn)全自動(dòng)生產(chǎn)，一人看管多臺(tái)機(jī)床。目前，機(jī)械手在這方面應(yīng)用最多，如上海柴油機(jī)廠的曲拐自動(dòng)車床和座圈自動(dòng)車床機(jī)械手，大連第二機(jī)床廠的自動(dòng)循環(huán)機(jī)械手，沈陽(yáng)仿形車床機(jī)械手，沈陽(yáng)第三機(jī)床廠的Y38滾齒機(jī)械手，青海第二機(jī)床廠的滾銑花鍵機(jī)床機(jī)械手等。由于這方面使用已有成熟的經(jīng)驗(yàn)，國(guó)內(nèi)一些機(jī)床廠已在這類機(jī)床產(chǎn)品出廠時(shí)舊附上機(jī)械手，或?yàn)橛脩糇孕邪惭b機(jī)械手提供條件。
2）注塑機(jī)有加料、合模、成型、分模等自動(dòng)工作循環(huán)，裝上機(jī)械手自動(dòng)裝卸工件，可實(shí)現(xiàn)全自動(dòng)生產(chǎn)。
3）沖床有自動(dòng)上下料沖壓循環(huán)，裝上機(jī)械手上下料，可實(shí)現(xiàn)沖壓生產(chǎn)自動(dòng)化。目前機(jī)械手在沖床上應(yīng)用有兩個(gè)方面：一是160t以上的沖床用機(jī)械手的較多。如沈陽(yáng)低壓開(kāi)關(guān)廠200t沖床磁力起動(dòng)機(jī)殼體下料機(jī)械手；一是用于多工位沖床用作沖壓件工位間步進(jìn)。如上海第二汽車配件廠的燈殼沖壓生產(chǎn)線機(jī)械手等。
2.在鑄、鍛、焊等如處理方面
在鍛造方面，機(jī)械手一般用作加熱爐，鍛壓加床或沖床的上下料和工件的傳送，其中包括多工位沖床的中間傳送。如天津第二鍛造廠研究了JS01通用機(jī)械手用于精鍛機(jī)上下料。
在鑄造方面，機(jī)械手應(yīng)用較多的是在熔模鑄造中，也用于澆鑄，造型，制芯及清理工作。美國(guó)Dochlcn-jarvis工廠是使用工業(yè)機(jī)械手最多的，約12萬(wàn)臺(tái)，主要用于從壓型中取出鑄件，然后用噴氣法清洗鑄件表面，該廠使用機(jī)械手后鑄件質(zhì)量得到了很大提高，穩(wěn)定性增強(qiáng)。
在焊接方面，這種機(jī)械手可分為點(diǎn)焊接機(jī)械手和弧焊接機(jī)械手。對(duì)于點(diǎn)焊接機(jī)械手，其手臂能伸縮，俯仰，回轉(zhuǎn)，手腕能擺動(dòng)，回轉(zhuǎn)，俯仰。至于弧焊接機(jī)械手，它的焊炬能作復(fù)雜三維曲線運(yùn)動(dòng)以調(diào)節(jié)焊接范圍。
3.選裝體零件生產(chǎn)流水線自動(dòng)化方面
采用機(jī)械手在旋轉(zhuǎn)體零件（如軸類、盤類、環(huán)類等）生產(chǎn)流水線上的機(jī)床之間傳送工件能夠提高生產(chǎn)線的自動(dòng)化。國(guó)內(nèi)已建成的這類自動(dòng)線很多，如沈陽(yáng)泵廠的深井泵軸承體加工自動(dòng)線（環(huán)類），大連電機(jī)廠的4號(hào)和5號(hào)電動(dòng)機(jī)軸加工自動(dòng)線（軸類），上海拖拉機(jī)齒輪廠的齒坯加工自動(dòng)線（盤類）等。加工箱體類零件的組合機(jī)床自動(dòng)線，一般采用隨行夾具傳送工件，也有采用機(jī)械手的，如上海動(dòng)力機(jī)廠的汽缸蓋加工自動(dòng)線轉(zhuǎn)為機(jī)械手。
4. 在裝配方面
工業(yè)機(jī)械手在裝配中的應(yīng)用，是近幾年國(guó)內(nèi)外研究和發(fā)展的一個(gè)重要方面，特別是在汽車制造業(yè)的汽車裝配自動(dòng)化和彈藥裝配等危險(xiǎn)作業(yè)上有很大的使用價(jià)值。目前裝配機(jī)械手正由串聯(lián)結(jié)構(gòu)向并聯(lián)結(jié)構(gòu)轉(zhuǎn)換。
1.2 本課題的研究目的及意義
工業(yè)機(jī)械手具有許多人類無(wú)法比擬的特點(diǎn)，滿足了社會(huì)化大生產(chǎn)的需要，其主要優(yōu)點(diǎn)如下：
1. 能代替人從事危險(xiǎn)、有害的操作。只要根據(jù)工作環(huán)境進(jìn)行合理設(shè)置，選擇適當(dāng)?shù)牟牧虾徒Y(jié)構(gòu)。機(jī)械手就可以在異常高溫或低溫、異常壓力和有害氣體、粉塵、放射線作用下，以及沖壓、滅火等危險(xiǎn)環(huán)境中勝任工作。工傷事故多的工種，如沖壓、壓鑄、熱處理、鍛造、噴漆以及有強(qiáng)烈紫外線照射的電弧焊等作業(yè)中，應(yīng)推廣工業(yè)機(jī)械手或機(jī)器人。
2. 能長(zhǎng)時(shí)間工作，不怕疲勞，可以把人從繁重單調(diào)的勞動(dòng)中解放出來(lái)，并能擴(kuò)大和延伸認(rèn)的功能。人在連續(xù)工作幾小時(shí)后，總會(huì)感到疲倦和勞累，而機(jī)械手只要注意維護(hù)、檢修，即能勝任長(zhǎng)時(shí)間的單調(diào)重復(fù)勞動(dòng)。
3. 動(dòng)作準(zhǔn)確，因此可以穩(wěn)定和提高產(chǎn)品的質(zhì)量，同時(shí)又可避免人為的操作失誤。
4. 機(jī)械手特別是通用工業(yè)機(jī)械手的通用性、靈活性好，能較好的適應(yīng)產(chǎn)品品種的不斷變化，以滿足柔性生產(chǎn)的需要。
5. 機(jī)械手能明顯的提高勞動(dòng)生產(chǎn)率和降低成本。
由于機(jī)械手在工業(yè)自動(dòng)化和信息化中發(fā)揮了以上巨大的作用，世界各國(guó)都很重視工業(yè)機(jī)械手的應(yīng)用及發(fā)展，機(jī)械手的應(yīng)用在我國(guó)還處于起步階段，就顯示了許多無(wú)法替代的優(yōu)點(diǎn)，展現(xiàn)了廣闊的應(yīng)用前景。近十幾年來(lái)，機(jī)械手的開(kāi)發(fā)不僅越來(lái)越優(yōu)化，而且涵蓋了許多領(lǐng)域，應(yīng)用的范疇十分廣闊。
成品電動(dòng)機(jī)機(jī)體形狀很復(fù)雜，從毛坯到成品需要很多道加工工序，各道工序及工序之間都要實(shí)現(xiàn)機(jī)體的移位及定位，這些工序如果全靠人工完成將大大增加工人的勞動(dòng)強(qiáng)度，不僅使加工質(zhì)量難以得到保證還增加了勞動(dòng)的危險(xiǎn)性。本課題的研究是為了設(shè)計(jì)出一種電動(dòng)機(jī)機(jī)體加工自動(dòng)線上用的輔助機(jī)械手，該機(jī)械手在機(jī)體加工自動(dòng)線能完成下料，轉(zhuǎn)位和翻轉(zhuǎn)等多種功能，提高生產(chǎn)效率，降低勞動(dòng)強(qiáng)度。
1.3 本課題的研究?jī)?nèi)容
本次設(shè)計(jì)的多功能機(jī)械手用于電動(dòng)機(jī)座加工自動(dòng)線上，主要由手爪、小臂、大臂等組成，具備上料、翻轉(zhuǎn)和轉(zhuǎn)位等多種功能，并按該自動(dòng)線的統(tǒng)一生產(chǎn)節(jié)拍和生產(chǎn)綱領(lǐng)完成以上動(dòng)作。本機(jī)械手為圓柱坐標(biāo)式機(jī)械手，自動(dòng)線圍繞機(jī)體布置，具有大手臂旋轉(zhuǎn)、小手臂伸縮、手指伸縮共2個(gè)自由度。其中大手臂旋轉(zhuǎn)是為了將工件從自動(dòng)線轉(zhuǎn)移到卸料工位上，小臂升降手指伸縮是重復(fù)自由度，目的是擴(kuò)大升降范圍，避免小手臂頻繁升降；驅(qū)動(dòng)方式為液壓驅(qū)動(dòng)，且選用雙聯(lián)葉片泵，系統(tǒng)壓力為2.5MPa，電機(jī)功率為3KW，共有推動(dòng)大臂旋轉(zhuǎn)油缸、小臂升降油缸、、手爪夾緊油缸共3個(gè)液壓缸；定位采用機(jī)械擋塊定位，定位精度為0.5～1mm，采用行程控制系統(tǒng)實(shí)現(xiàn)點(diǎn)位控制。
本機(jī)械手裝置應(yīng)具備如下功能；
1. 具有友好的人機(jī)界面，以保證人機(jī)通訊、人機(jī)互助和人機(jī)協(xié)同工作。
2.能夠自動(dòng)完成系統(tǒng)所要求的動(dòng)作，具有連續(xù)工作、單周期工作、單步工作、自動(dòng)返回原點(diǎn)、手動(dòng)返回原點(diǎn)、手動(dòng)操作等功能。
3.在保證精度的前提下，有一定的容錯(cuò)性。
4.能夠依次對(duì)電動(dòng)機(jī)座完成上料、轉(zhuǎn)位、翻轉(zhuǎn)等輔助加工功能。
5.在保證完成以上功能的前提下具有一定的通用性，使該機(jī)械手在整個(gè)電動(dòng)機(jī)座加工自動(dòng)線都具有一定的適應(yīng)性。
2 機(jī)械手的總體設(shè)計(jì)
2.1 總體方案的比較與選定
2.1.1 各種坐標(biāo)形式機(jī)械手的比較
按坐標(biāo)形式分，機(jī)械手主要有以下四種不同的類型：
1. 直角坐標(biāo)式
2. 圓柱坐標(biāo)式
3. 球坐標(biāo)式
4. 平面多關(guān)節(jié)式
根據(jù)設(shè)計(jì)要求，本課題設(shè)計(jì)的機(jī)械手需要在電動(dòng)機(jī)座加工自動(dòng)線卸料，包括上料，升降，轉(zhuǎn)位，等多種功能。結(jié)合設(shè)計(jì)要求對(duì)各種坐標(biāo)形式的機(jī)械手的優(yōu)缺點(diǎn)作出評(píng)析。
如下：
1. 直角坐標(biāo)式機(jī)械手（如圖2.1）。這種機(jī)械手所有的送放運(yùn)動(dòng)均為直線運(yùn)動(dòng)，結(jié)構(gòu)簡(jiǎn)單，直觀性好，便于實(shí)現(xiàn)一定的精度要求，但本機(jī)械手需要在多個(gè)工位上完成輔助加工功能，故在相同的動(dòng)作范圍內(nèi)其所需要的空間位置大，靈活性差，同時(shí)由于手爪部分移動(dòng)，不利于電液集中配置。
圖2.1 直線坐標(biāo)式機(jī)械手
2. 圓柱坐標(biāo)式機(jī)械手（如圖2.2）。這是一種回轉(zhuǎn)型機(jī)械手，其手臂除了可以伸縮，可以升降外，還可以繞立柱回轉(zhuǎn)。這種機(jī)械手與直角坐標(biāo)式機(jī)械手相比，占地面積小而活動(dòng)范圍大，結(jié)構(gòu)亦比較簡(jiǎn)單，并能達(dá)到較高的定位精度。但是，它的手臂的升降受到機(jī)械手結(jié)構(gòu)的限制，距離地面總有一定的距離，不能從地面抓取物件，因此不能完成上料的工序。
圖2-2 圓柱坐標(biāo)式機(jī)械手
1—手部 2—腕部 3—臂部
3.球坐標(biāo)式機(jī)械手（如圖2.3）。這種機(jī)械手與圓柱坐標(biāo)式機(jī)械手相比，在占有同樣大小的空間情況下，可以擴(kuò)大工作范圍，能將手臂伸向地面抓取物件。其缺點(diǎn)是運(yùn)動(dòng)的直觀性差，結(jié)構(gòu)較復(fù)雜，且臂部有兩個(gè)回轉(zhuǎn)運(yùn)動(dòng)，位置精度誤差較大。
圖2.3 球坐標(biāo)式機(jī)械手
4.多關(guān)節(jié)坐標(biāo)式機(jī)械手（如圖2.4）。這種機(jī)械手可以在以臂部最大伸展長(zhǎng)度為半徑的球體空間范圍內(nèi)任意抓取物件，靈活性大。它與其他坐標(biāo)形式的機(jī)械手相比，所占空間最小。但其運(yùn)動(dòng)直觀性差，臂部前端的位置由多個(gè)回轉(zhuǎn)運(yùn)動(dòng)決定，要達(dá)到較高的運(yùn)動(dòng)精度比較困難，為此必須提高制造精度，因而使設(shè)計(jì)和制造均較為復(fù)雜。
圖2.4 多關(guān)節(jié)坐標(biāo)式機(jī)械手
2.1.2選定的兩個(gè)機(jī)械手方案的概述及比較
根據(jù)本課題的設(shè)計(jì)要求，該機(jī)械手能夠完成上料、升降、轉(zhuǎn)位工件等多種功能，所以，在這里設(shè)計(jì)了四個(gè)機(jī)械手將要到達(dá)并完成輔助加工的工位，依次是：上料工位、升降工位、轉(zhuǎn)位工位、再次轉(zhuǎn)位工位（見(jiàn)圖2.6和2.7）。機(jī)械手在一個(gè)周期內(nèi)的動(dòng)作過(guò)程如下：
一．上料。機(jī)械手在運(yùn)動(dòng)開(kāi)始前面向第一工位。開(kāi)始工作后，機(jī)械手的小手臂的升降缸將手部5下降到取料位置，手部上的定位壓盤正卡在工件已加工完的上端止口及其端面上，同時(shí)，手指伸縮油缸1的活塞桿下端連接著帶圓錐面得推動(dòng)桿6，使內(nèi)撐式手部的三個(gè)手指伸入到工件內(nèi)的空槽中。
二．完成以上動(dòng)作后，機(jī)械手轉(zhuǎn)向第二工位，將工件升起，小手臂2的油缸上升，將工件提起到預(yù)定的高度。
三．接下來(lái)，大手臂回轉(zhuǎn)90度（當(dāng)前輸送帶前進(jìn)到終點(diǎn)發(fā)信）。
四．然后小手臂下降到工件準(zhǔn)確地放到轉(zhuǎn)載裝置前輸送帶的適當(dāng)位置上。
完成一個(gè)周期的動(dòng)作后，機(jī)械手轉(zhuǎn)向第一工位，處于“回到原點(diǎn)”狀態(tài)。這時(shí)，第一工位的專機(jī)已經(jīng)完成加工處于“等候上料”狀態(tài)，機(jī)械手在第一工位再次完成上料后轉(zhuǎn)向第二工位，這時(shí)，在第一工位加工完畢的機(jī)體已經(jīng)順著自動(dòng)線傳至第二工位，機(jī)械手將其轉(zhuǎn)位使其完成第二工位的加工。在連續(xù)工作狀態(tài)中機(jī)械手的動(dòng)作過(guò)程如上所述依次循環(huán)。
總結(jié)上述各種形式的機(jī)械手，在滿足設(shè)計(jì)要求的前提下設(shè)計(jì)出以下兩種方案。
方案一：外形圖及運(yùn)動(dòng)簡(jiǎn)圖如下：
圖2.5 方案一外形圖
圖2.6 方案一運(yùn)動(dòng)簡(jiǎn)圖
這是一種屈伸型機(jī)械手，該機(jī)械手具有與人體上肢相類似的結(jié)構(gòu)。臂部由大臂和小臂兩個(gè)部分組成。除了大臂本身具有回轉(zhuǎn)和俯仰運(yùn)動(dòng)外，小臂相對(duì)于大臂也可以俯仰，通過(guò)大臂和小臂的俯仰來(lái)實(shí)現(xiàn)手臂的伸縮，通過(guò)機(jī)身的回轉(zhuǎn)來(lái)實(shí)現(xiàn)使手臂面向不同的工位。該機(jī)械手有E1-E5（見(jiàn)圖2.6）共5個(gè)自由度，其中：
E1：機(jī)身繞機(jī)座回轉(zhuǎn)
E2：大臂的俯仰
E3：小臂的俯仰
E4：手腕的俯仰
E5：手腕的回轉(zhuǎn)
這種機(jī)械手采用直線式流水線，待加工的電動(dòng)機(jī)座從流水線上依次流A,B,C,D四個(gè)工位，機(jī)械手通過(guò)機(jī)身的回轉(zhuǎn)依次停在四個(gè)工位，分別完成下料、轉(zhuǎn)位、翻轉(zhuǎn)、再次轉(zhuǎn)位四個(gè)輔助加工動(dòng)作。通過(guò)大臂、小臂和手腕的俯仰使機(jī)械手到達(dá)四個(gè)工位點(diǎn)，通過(guò)手腕的俯仰和翻轉(zhuǎn)使手爪能夠有正確的夾持姿態(tài)。
方案二：外形圖及運(yùn)動(dòng)簡(jiǎn)圖如下，見(jiàn)下圖
圖2.8 方案二外形圖
圖2.9 方案二運(yùn)動(dòng)簡(jiǎn)圖
這是一種圓柱坐標(biāo)坐標(biāo)式機(jī)械手。該機(jī)械手由機(jī)座、機(jī)身（即立柱）、大臂、小臂、手腕和手爪組成。有E1-E3共2自由度（立柱升降自由度E2和小臂升降自由度E3是重復(fù)自由度），其中：
E1:大手臂回轉(zhuǎn)
E2:手指伸縮
E3:小手臂升降
本機(jī)械手為圓柱坐標(biāo)式機(jī)械手，自動(dòng)線圍繞機(jī)體布置，具有大手臂旋轉(zhuǎn)、小手臂伸縮、手指伸縮共2個(gè)自由度。其中大手臂旋轉(zhuǎn)是為了將工件從自動(dòng)線轉(zhuǎn)移到卸料工位上，小臂升降手指伸縮是重復(fù)自由度，目的是擴(kuò)大升降范圍，避免小手臂頻繁升降；驅(qū)動(dòng)方式為液壓驅(qū)動(dòng)，且選用雙聯(lián)葉片泵，系統(tǒng)壓力為2.5MPa，電機(jī)功率為3KW，共有推動(dòng)大臂旋轉(zhuǎn)油缸、小臂升降油缸、、手爪夾緊油缸共3個(gè)液壓缸；定位采用機(jī)械擋塊定位，定位精度為0.5～1mm，采用行程控制系統(tǒng)實(shí)現(xiàn)點(diǎn)位控制。
該機(jī)械手的工作流程圖如下：
圖2.10 方案二的工作流程圖
該機(jī)械手由電動(dòng)機(jī)驅(qū)動(dòng)回轉(zhuǎn)缸里的小齒輪，小齒輪通過(guò)與大齒輪嚙合來(lái)驅(qū)動(dòng)大手臂回轉(zhuǎn)；由直動(dòng)式液壓缸推動(dòng)小臂升降；由直動(dòng)式液壓缸推動(dòng)手指夾緊與放松。
在工作中，自動(dòng)流水線環(huán)繞機(jī)座兩旁布置，機(jī)械手在一個(gè)工位完成輔助加工后，縮回手臂，大手臂依次回轉(zhuǎn)到下一工位，伸出手臂完成相應(yīng)的功能。
兩種方案通過(guò)流水線的不同布置都能使手爪到達(dá)指定的工位并且都能夠?qū)崿F(xiàn)所要求的功能，手爪都具有足夠的自由度，能從正確的方位夾持電動(dòng)機(jī)座體。兩種方案都具有電液集中，占地面積小，可以從地面上抓取工件的優(yōu)點(diǎn)。所不同的是：方案一通過(guò)腰部的回轉(zhuǎn)、大臂的俯仰及小臂的俯仰來(lái)使手爪到達(dá)正確的工位，而方案二是通過(guò)大手臂回轉(zhuǎn)、小手臂的升降和手指伸縮來(lái)使手爪到達(dá)正確的工位。
但是，方案一運(yùn)動(dòng)直觀性差，結(jié)構(gòu)復(fù)雜。首先,臂部位置由多個(gè)回轉(zhuǎn)運(yùn)動(dòng)決定，手臂在俯仰時(shí)底部回轉(zhuǎn)角度的誤差容易在手臂端部造成誤差擴(kuò)大，通過(guò)大臂、小臂、手腕的回轉(zhuǎn)誤差累積，最終容易使手爪位置與指定位置有較大偏差。其次，越靠近機(jī)身的俯仰運(yùn)動(dòng)所需要的驅(qū)動(dòng)力越大，使整個(gè)系統(tǒng)各液壓缸工作壓力相差很大，不易配置液壓驅(qū)動(dòng)系統(tǒng)且回轉(zhuǎn)缸出力不大。再次，方案一的手臂有多種屈伸狀態(tài)，則需要很多的定位裝置，而回轉(zhuǎn)液壓缸內(nèi)空間狹小，不宜布置過(guò)多的機(jī)械擋塊。如果改采用連續(xù)軌跡控制的機(jī)械手，成本太高。所以在第二種方案中回轉(zhuǎn)缸里大小齒輪的嚙合來(lái)促使手臂回轉(zhuǎn)，通過(guò)行程擋鐵與形成開(kāi)關(guān)來(lái)實(shí)現(xiàn)對(duì)回轉(zhuǎn)的控制。
綜上所述，本課題采用第二種方案。
1 Introduction
Manipulator, the English name of mechanical hand, is the manpower and arms to imitate certain actions and functions of a fixed procedure for the capture, handling objects or tools of the automatic operation device operation.
Industrial robot that is used in industrial production robot is a programmable robot hand. It is in the late fifties, developed rapidly in recent years the importance of automation equipment, automation is an important means to achieve winter. At present, in all areas of production, in order to improve production efficiency and product quality, to achieve safe production, have used a variety of different forms, different functions of the robot. The emergence of the robot, in many production processes have replaced the manual, the industrial automation has made significant development, which not only greatly improve labor productivity, improved working conditions, reduce labor intensity, but also mass production With the guarantee of quality and technology, because of this, the robot design and development of industrial technology has become an important issue at present.
1.1 Background and Development of
Manipulator in industrial production are widely used in machining, forging, casting, stamping, welding, assembly, painting, heat treatment and other industries, especially in the heavy, high temperature toxic, radioactive, and more dust and other harsh dangerous work environment, the robot Because of significant advantages has been taken seriously. The following is a robot in the typical industrial applications:
1. In the realization of single automation
1) various types of semi-automatic lathes, automatic step, into the knife, cutting knife and release the function back, but still needs manual loading. Fitted with mechanical hand can be realized fully automatic production, one person in more than one machine. Currently, the mechanical hand in this respect the most widely used, such as Shanghai Diesel Engine Plant crank automatic lathes and seat automatic lathe robot, Dalian Second Machine Tool Plant of automatic loop manipulator, Shenyang copying lathe robot, Shenyang Third Machine Tool Plant of Y38 hobbing mechanical hand, the second machine tool plant in Qinghai spline roller milling machine robots. Since this has proven experience in the use of some domestic machine tool plant has been in such an old machine attached to the factory robots, or users themselves provide the conditions for installation of mechanical hand.
2) injection molding machine with feeding, clamping, forming, parting, such as automatic work cycle, fitted with automatic loading and unloading the workpiece manipulator can realize automatic production.
3) Punch press with automatic loading and unloading cycles, fitted with mechanical hand cutting, stamping automation can be realized. The current robot applications in the red bed has two aspects: First, more than 160t mechanical hand with more punch. Such as low-voltage switchgear plant in Shenyang 200t cutting punch shell magnetic starter manipulator; first multi-station presses used for stamping station between the steps. Such as auto parts plant in Shanghai Second lamp shell punch line robots.
2. In casting, forging, welding, etc., such as processing
In forging, the mechanical hand normally used for heating, forging an extra bed or press the up and down the transmission of material and artifacts, including the middle of multi-station transfer presses. Such as Tianjin, the second of the JS01 Forge General manipulator forging machine for loading and unloading.
In casting, the mechanical hand is used more often in the investment casting, also used for casting, molding, core making and clean-up work. U.S. Dochlcn-jarvis plant is the largest use of industrial robots, about 12 million units, mainly used to remove from the pressure-type casting, and then clean the casting surface jet method, the plant after the use of mechanical hand has been greatly improved casting quality, stability enhanced.
In welding terms, this robot can be divided into point arc welding robot and welding robot. For spot welding robot, the arm can stretch, pitch, rotating the wrist to swing, swing, pitch. As for the arc welding robot, and its complex three-dimensional welding torch can be curved to adjust the welding range.
3. Optional Parts production line automation
Hand in the rotating body by mechanical parts (such as axle, disc type, ring type, etc.) on the production line is transferred between parts of machine tools can improve the production line automation. China has built many of these auto lines, such as the deep well pump plant in Shenyang, automatic production line for bearing body (ring type), motor plant in Dalian 4 and 5, automatic production line for the motor shaft (shaft), the Shanghai factory gear blank Tractor Gear automatic production line (disk type) and so on. Processing machine tool box part of the automatic line, commonly used to send the workpiece pallet, there is also the manipulator, such as the Shanghai Power Machinery Factory automatic production line for the cylinder head into the robot.
4. In the assembly area
Industrial machinery in the assembly of hand, is the research and development at home and abroad in recent years, an important aspect, especially in the automotive industry vehicle assembly automation and ammunition assembly is very dangerous to use operationally value. Present assembly structure of the robot by the serial to parallel conversion structure.
1.2 The purpose and significance of the research project
Industrial robots have many human beings can not match the characteristics of large-scale production to meet the needs of society, its main advantages are as follows:
1. Can replace people in dangerous and harmful operations. As long as a reasonable working environment based on set, select the appropriate materials and structures. Robot can in abnormal high or low temperatures, abnormal pressure and harmful gases, dust, radiation, under, and stamping, fire and other dangerous environments the task. Many types of accidents, such as stamping, casting, heat treatment, forging, painting, and a strong ultraviolet radiation of the electric arc welding and other operations, should be the promotion of industrial machinery or robots.
2. Can work long hours, fear of fatigue, can be from the heavy monotonous work of liberation, and to expand and extend the function of recognition. After several hours of continuous work people always feel tired and fatigue, and mechanical hand as long as the attention to maintenance, overhaul, that is, capable of performing repetitive work a long time.
3. Action is accurate, it can stabilize and improve product quality, while avoiding the human operational errors.
4. In particular, general industrial robot manipulator versatility, flexibility, can better adapt to changing product variety to meet the needs of flexible production.
5. Manipulator can significantly improve productivity and reduce costs.
The robot in industrial automation and information technology has played a more significant role in the world attach great importance to industrial robot application and development of robotic applications in China is still in its infancy, it shows a lot of irreplaceable advantages, showing a broad application prospects. Over the last decade, the development of the robot is not only more and more optimized, and it covers many areas, the application scope is very broad.
Product motor body shape is very complex, from rough to finished product requires a lot of channel processing procedures, of the procedures and processes must be achieved between the movement and position of the body, these processes will be done manually if the greatly increased thanks to the labor intensity of workers, not only difficult to ensure the machining quality of labor also increased the risk. Research of this subject is to design a motor body processing aid used in automated robotic line, the robot can automatic production line in the body to complete the next, turn the bit and flip, and other functions, improve productivity and reduce labor intensity.
1.3 The research topic
The multi-functional manipulator designed for automatic processing of the motor seat online, mainly by the gripper, the arm, the arm and other components, with feeding, turning and translocation of other functions, according to the unity of the automatic line takt and production program to complete the above action. The robot is a cylindrical coordinate manipulator, automatic line around the body layout, with a large arm rotation, small arms stretching, fingers stretching a total of 2 degrees of freedom. Rotate the arm of which is to be transferred to the workpiece from the automatic line on the discharge station, the arm movements are repeated finger stretching degrees of freedom, the purpose is to expand the range of movements to avoid frequent movements of small arms; drive for the hydraulic drive, and the selection of double pump, system pressure 2.5MPa, motor power 3KW, there to promote the rotating cylinder arm, arm lift cylinder,, a total of three gripper cylinder clamping hydraulic cylinder; positioning mechanical stop position, positioning accuracy is 0.5 ~ 1mm, stroke control system using control points.
The robotic device should have the following functions;
1. Has a friendly interface, in order to guarantee machine communication, human solidarity and human work together.
2. Can automatically complete the requested action system, with continuous work, single-cycle work, the work of a single-step, automatic return to origin, manual return to origin, manual operation and other functions.
3. In the given accuracy, there is some fault tolerance.
4. To complete the turn on the motor seat, turn the bit, flip and other auxiliary processing functions.
5. In ensuring the completion of the above function under the premise has a certain generality, so that the robot in automatic production line for the seat motor has a certain flexibility.
2 the overall design of the robot
2.1 Comparison of the overall program with the selected
Coordinates in the form of various robotic 2.1.1 Comparison
The form of points by coordinates, the robot has the following four different types:
1. Cartesian Coordinate
2. Cylindrical Coordinate
3. Spherical coordinate type
4. Planar multi-joint type
According to design requirements, the issue needs to design the robot automatic production line for motor discharge seat, including feeding, lifting, transfer, and other features. Coordinate with the design requirements of various forms of mechanical hand to Review the advantages and disadvantages.
As follows:
1. Cartesian coordinate manipulator (Figure 2.1). This mechanical hand movements are all put give linear motion, the structure is simple, intuitive, and easy to achieve a certain degree of accuracy, but the robots need to be completed in a number of station auxiliary processing functions, it is within the same range of motion of its spatial location required for a large, inflexible, and because the gripper part of the move, is not conducive to concentration of electro-hydraulic configuration.
Figure 2.1 Linear coordinate manipulator
2. cylindrical coordinate manipulator (Figure 2.2). This is a transition back to the robot, in addition to its retractable arm that can lift, you can also turn around the column. The Cartesian robot manipulator with compared to the scope of activities covers an area of ??small and large, the structure is also relatively simple and can achieve high positioning accuracy. However, its movements by the robot arm structural limitations, there is always a certain distance from the ground and can not grab the object from the ground, it can not be completed on the material processes.
Figure 2-2 cylindrical coordinate manipulator
1 - Hand 2 - wrist 3 – arm
3. spherical coordinate manipulator (Figure 2.3). The cylindrical coordinate robot manipulator and compared occupy the same space in the case, you can expand the scope of work, the arm extending toward the ground can grab objects. The disadvantage is the poor visual movement, more complex structure, and the arm has two rotary movement, position accuracy errors.
Figure 2.3 The spherical coordinate manipulator
4. multi-joint coordinate manipulator (Figure 2.4). The robot can be extended to the maximum length of arm radius sphere crawl space any objects within, flexibility. It coordinates with other forms of mechanical hand than for the smallest. Intuitive, but its movement is poor, the location of the front arm rotary movement by a number of decisions, the movement to achieve a higher precision is difficult, for the need to improve manufacturing precision, and thus make the design and manufacturing are more complex.
Figure 2.4 Coordinate multi-joint manipulator
2.1.2 The two selected overview of the robot program and comparison
According to the project design requirements, the robot can do the feeding, lifting, transfer jobs and other functions, so here the design of the four mechanical hand to reach and complete auxiliary processing station, in order: feeding station , lift station, transfer station, once again shifted station (see Figure 2.6 and 2.7). Robot moves in a cycle as follows:
One. Feeding. In the beginning of the campaign in front of the robot to the first station. Started work, a small robot arm lifting cylinder 5 will hand down to get material position, hand position on the pressure plate is stuck in the workpiece has been processed and completed the Mouth of the top end surface at the same time, fingers stretching cylinder 1, the lower end of piston rod was connected to the push rod with a conical surface 6, so that the support-type hand three fingers into the empt