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1、 機(jī)電一體化的做法 機(jī)電一體化的做法 1 數(shù)控機(jī)床科普知識(shí) 數(shù)字控制機(jī)床是用數(shù)字代碼形式的信息(程序指令)，控制刀具按給定的工作程序、運(yùn)動(dòng)速度和軌跡進(jìn)行自動(dòng)加工的機(jī)床，簡(jiǎn)稱數(shù)控機(jī)床。數(shù)控機(jī)床具有廣泛的適應(yīng)性，加工對(duì)象改變時(shí)只需要改變輸入的程序指令；加工性能比一般自動(dòng)機(jī)床高，可以精確加工復(fù)雜型面，因而適合于加工中小批量、改型頻繁、精度要求高、形狀又較復(fù)雜的工件，并能獲得良好的經(jīng)濟(jì)效果。 隨著數(shù)控技術(shù)的發(fā)展，采用數(shù)控系統(tǒng)的機(jī)床品種日益增多，有車床、銑床、鏜床、鉆床、磨床、齒輪加工機(jī)床和電火花加工機(jī)床等。此外還有能自動(dòng)換刀、一次裝卡進(jìn)行多工序加工的加工中心、車削中心等。 1948

2、年，美國(guó)帕森斯公司接受美國(guó)空軍委托，研制飛機(jī)螺旋槳葉片輪廓樣板的加工設(shè)備。由于樣板形狀復(fù)雜多樣，精度要求高，一般加工設(shè)備難以適應(yīng)，于是提出計(jì)算機(jī)控制機(jī)床的設(shè)想。1949年，該公司在美國(guó)麻省理工學(xué)院伺服機(jī)構(gòu)研究室的協(xié)助下，開始數(shù)控機(jī)床研究，并于1952年試制成功第一臺(tái)由大型立式仿形銑床改裝而成的三坐標(biāo)數(shù)控銑床，不久即開始正式生產(chǎn)。 當(dāng)時(shí)的數(shù)控裝置采用電子管元件，體積龐大，價(jià)格昂貴，只在航空工業(yè)等少數(shù)有特殊需要的部門用來加工復(fù)雜型面零件；1959年，制成了晶體管元件和印刷電路板，使數(shù)控裝置進(jìn)入了第二代，體積縮小，成本有所下降；1960年以后，較為簡(jiǎn)單和經(jīng)濟(jì)的點(diǎn)位控制數(shù)控鉆床，和直線控制數(shù)控銑床得

3、到較快發(fā)展，使數(shù)控機(jī)床在機(jī)械制造業(yè)各部門逐步獲得推廣。 為了保證機(jī)床具有很大的工藝適應(yīng)性能和連續(xù)穩(wěn)定工作的能力，數(shù)控機(jī)床結(jié)構(gòu)設(shè)計(jì)的特點(diǎn)是具有足夠的剛度、精度、抗振性、熱穩(wěn)定性和精度保持性。進(jìn)給系統(tǒng)的機(jī)械傳動(dòng)鏈采用滾珠絲杠、靜壓絲杠和無間隙齒輪副等，以盡量減小反向間隙。機(jī)床采用塑料減摩導(dǎo)軌、滾動(dòng)導(dǎo)軌或靜壓導(dǎo)軌，以提高運(yùn)動(dòng)的平穩(wěn)性并使低速運(yùn)動(dòng)時(shí)不出現(xiàn)爬行現(xiàn)象。 由于采用了寬調(diào)速的進(jìn)給伺服電動(dòng)機(jī)和寬調(diào)速的主軸電動(dòng)機(jī)，可以不用或少用齒輪傳動(dòng)和齒輪變速，這就簡(jiǎn)化了機(jī)床的傳動(dòng)機(jī)構(gòu)。機(jī)床布局便于排屑和工件裝卸，部分?jǐn)?shù)控機(jī)床帶有自動(dòng)排屑器和自動(dòng)工件交換裝置。大部分?jǐn)?shù)控機(jī)床采用具有微處理器的可編程序控制器，

4、以代替強(qiáng)電柜中大量的繼電器，提高了機(jī)床強(qiáng)電控制的可靠性和靈活性。 隨著微電子技術(shù)、計(jì)算機(jī)技術(shù)和軟件技術(shù)的迅速發(fā)展，數(shù)控機(jī)床的控制系統(tǒng)日益趨向于小型化和多功能化，具備完善的自診斷功能；可靠性也大大提高；數(shù)控系統(tǒng)本身將普遍實(shí)現(xiàn)自動(dòng)編程。未來數(shù)控機(jī)床的類型將更加多樣化，多工序集中加工的數(shù)控機(jī)床品種越來越多；激光加工等技術(shù)將應(yīng)用在切削加工機(jī)床上，從而擴(kuò)大多工序集中的工藝范圍；數(shù)控機(jī)床的自動(dòng)化程度更加提高，并具有多種監(jiān)控功能，從而形成一個(gè)柔性制造單元，更加便于納入高度自動(dòng)化的柔性制造系統(tǒng)中。 眾所周知，一部機(jī)器的基本構(gòu)成包括原動(dòng)機(jī)、傳動(dòng)部分、執(zhí)行部分和控制部分。其中傳動(dòng)部分是絕大多數(shù)機(jī)器不可缺少的重

5、要組成部分。從原動(dòng)機(jī)到工作機(jī)部分的變速、改變運(yùn)動(dòng)方向、改變運(yùn)動(dòng)方式、動(dòng)力與運(yùn)動(dòng)的傳遞分配等等功能。都是由傳動(dòng)裝置完成的。在一些機(jī)器中(如機(jī)床、汽車)中傳動(dòng)裝置占整機(jī)的大部分，所以機(jī)器的工作性能和運(yùn)轉(zhuǎn)費(fèi)用在很大程度上取決于傳動(dòng)部分(傳動(dòng)裝置)的優(yōu)劣。因此，為了適應(yīng)市場(chǎng)對(duì)機(jī)械產(chǎn)品的要求，提高傳動(dòng)裝置的設(shè)計(jì)水平具有重要的意義。 長(zhǎng)期以來，我國(guó)在設(shè)計(jì)機(jī)械產(chǎn)品時(shí)，一般沿用傳統(tǒng)的設(shè)計(jì)方法，機(jī)械產(chǎn)品的設(shè)計(jì)是一個(gè)病態(tài)結(jié)構(gòu)的、反復(fù)迭代的復(fù)雜過程，耗費(fèi)設(shè)計(jì)者大量的時(shí)間和精力，因此，無論從設(shè)計(jì)性能和設(shè)計(jì)速度上均遠(yuǎn)遠(yuǎn)滿足不了用戶的要求，形成了先進(jìn)產(chǎn)品要求與落后的設(shè)計(jì)方法上的矛盾。同時(shí)，市場(chǎng)競(jìng)爭(zhēng)的加劇，亦要求產(chǎn)品朝著

6、高質(zhì)量、低成本、短周期的方向發(fā)展RI。目前，機(jī)械中常用傳動(dòng)的設(shè)計(jì)方法常用理論設(shè)計(jì)法。它是根據(jù)現(xiàn)有的科學(xué)技術(shù)理論及實(shí)踐知識(shí)而進(jìn)行的設(shè)計(jì)，所以，常用的設(shè)計(jì)計(jì)算公式多是在某些假設(shè)的條件下進(jìn)行理論推導(dǎo)，再引入一系列的修正系數(shù)，而得到的半理論半經(jīng)驗(yàn)公式。利用這些公式手算時(shí)，需要查一系列的有關(guān)表格或線圖來確定修正系數(shù)和某些參數(shù)，過程煩瑣費(fèi)時(shí):尤其是機(jī)械設(shè)計(jì)是一個(gè)不斷修改、不斷完善的過程。無數(shù)事實(shí)證明，富有經(jīng)驗(yàn)的優(yōu)秀設(shè)計(jì)師往往能比剛出校門、同樣富有才華的設(shè)計(jì)師以較快的速度設(shè)計(jì)出較好的產(chǎn)品來。專家系統(tǒng)技術(shù)能幫助我們實(shí)現(xiàn)專家設(shè)計(jì)經(jīng)驗(yàn)的歸納和利用，使經(jīng)驗(yàn)的繼承和發(fā)展大大超越了“師徒之間”的時(shí)空限制，從而大大推進(jìn)了

7、設(shè)計(jì)質(zhì)量和效率的提高，因而為使傳動(dòng)的設(shè)計(jì)適應(yīng)于產(chǎn)品的市場(chǎng)需求，開發(fā)機(jī)械傳動(dòng)設(shè)計(jì)專家系統(tǒng)，使傳動(dòng)設(shè)計(jì)速度快、計(jì)算準(zhǔn)確、方案優(yōu)化成為必然的趨勢(shì)。 2 介紹 在這個(gè)文件中，機(jī)電一體化采取的是為端銑操作數(shù)控銑床制定一個(gè)數(shù)學(xué)模型，并模擬其行為。數(shù)學(xué)模型的伺服電機(jī)控制XY工作臺(tái)。其它方面的發(fā)展是同提出的為端銑操作的模型整合在一起，MATLAB是用來模擬仿真的。實(shí)驗(yàn)的初衷是建立在XY工作臺(tái)上履行銑削操作。仿真的結(jié)果驗(yàn)證了實(shí)驗(yàn)結(jié)果。這樣的數(shù)學(xué)模型可用于評(píng)價(jià)一個(gè)新的設(shè)計(jì)。因此，一個(gè)新的設(shè)計(jì)在市場(chǎng)上將導(dǎo)致時(shí)間和成本大幅度減少。 日本在20世紀(jì)80年代已經(jīng)介紹了機(jī)電一體化技術(shù)是一個(gè)概念，盡管人民提及任何系

8、統(tǒng)都具有機(jī)械、電氣、電子元件等，例如洗衣機(jī)、復(fù)印機(jī)、數(shù)控機(jī)床等，都具有機(jī)電一體化系統(tǒng)，是一種真正的機(jī)電一體化設(shè)計(jì)原理。在傳統(tǒng)的設(shè)計(jì)方法中，系統(tǒng)的組成部分都有各自的專家來完成。例如：一名機(jī)械工程師設(shè)計(jì)機(jī)械部分，而電機(jī)工程師則設(shè)計(jì)電器元件等等。因?yàn)槊總€(gè)設(shè)計(jì)師都有一定的安全因素要取決于其它無知的領(lǐng)域的合作，從而使整體的價(jià)格變大，且系統(tǒng)變得龐大和昂貴。在機(jī)電一體化的設(shè)計(jì)方法中，整個(gè)系統(tǒng)被認(rèn)為要顧及到各個(gè)部件，無論是機(jī)械、電氣、還是電子設(shè)備。由于整體的安全因素小了，因此，該系統(tǒng)的設(shè)計(jì)尺寸和費(fèi)用減少了。 在這個(gè)文件中，機(jī)電控制的方法以研究數(shù)控機(jī)床為主，在援助過程中新設(shè)計(jì)了一種數(shù)控機(jī)床就座。這項(xiàng)研究需要模

9、型的加工過程。數(shù)控端銑的特點(diǎn)在于以正規(guī)的序列個(gè)別消減，相當(dāng)于每齒的接觸。這些消減多次強(qiáng)烈重疊。都是為了預(yù)知這些瞬時(shí)切削力、機(jī)械理論的運(yùn)用等。在不同刀具的切削點(diǎn)，該力模型的發(fā)展需要工作臺(tái)中的表和刀具作為輸入?yún)?shù)，并給出了瞬時(shí)力作為輸出。機(jī)械傳動(dòng)元件中組成XY工作臺(tái)的電機(jī)軸和滾珠絲杠也要考慮在內(nèi)。在這個(gè)數(shù)學(xué)模型中，在機(jī)械零件的精度方面，由于剛度力學(xué)起著重要的作用，因此，他們也在考慮之列。而該模型中XY工作臺(tái)的伺服電機(jī)則來自于Kataria 和Mehta?？恐@些模型，MATLAB被用于模擬仿真。機(jī)床操作中的附件也需要設(shè)計(jì)和制作，它們附著在已有的XY工作臺(tái)上來驗(yàn)證實(shí)驗(yàn)的仿真結(jié)果。 3 實(shí)驗(yàn)初步成立

10、 在數(shù)控銑床的研究中提出的假定是必須做的。在我們的研究中端銑通過一個(gè)可用的XY工作臺(tái)來實(shí)現(xiàn)。所以一個(gè)框架的設(shè)計(jì)和制作要能夠支持馬達(dá)和主軸。圖1顯示了在試驗(yàn)中幀的設(shè)計(jì)和制作。圖2用相片顯示了一套完整的模型。附件中的主軸以這樣的一種方式來設(shè)計(jì)，其一端與交流感應(yīng)電機(jī)軸連接，并由其帶動(dòng)旋轉(zhuǎn)，而另一端連接在修飾銑刀用的鉆夾頭上。其它組件下次解釋。 3.0 主軸電機(jī) 在生產(chǎn)技術(shù)手冊(cè)中，動(dòng)力所要求的端銑都做了，通過一個(gè)高速鋼刀具動(dòng)力來切削鋁，主軸電機(jī)選定為：220伏特，每分鐘1440轉(zhuǎn)、250瓦特、單三相交流感應(yīng)電動(dòng)機(jī)。 3.1 幀 在立銑結(jié)構(gòu)中，其橫向連接如圖1所示，是起決定性作用的，因

11、為在切削過程中它消減了對(duì)電機(jī)和主軸的彎曲應(yīng)力。這個(gè)環(huán)節(jié)被設(shè)計(jì)為簡(jiǎn)支梁，其橫截面選定為：35毫米*35毫米，3毫米厚，空心。 3.2 刀具夾緊裝置 在實(shí)際的數(shù)控機(jī)床中，設(shè)計(jì)條狀機(jī)械裝置是為了保證刀具。不過為了確保系統(tǒng)簡(jiǎn)單，在這里鉆孔卡盤的改裝是為了持有刀具。 3.3 軸承 軸承安裝于車架上是為了來固定主軸的，來自于主軸上的力主要是彎曲。所以軸承承受徑向力。因此，SKF公司主要選定深溝球軸承6004 3.4 單片機(jī) 該系統(tǒng)的反應(yīng)是通過觀察單片機(jī)上所用的軟件來實(shí)現(xiàn)的，而另一個(gè)DMC軟件是用來溝通控制器卡的。DMC1822是一所兩軸控制器用來控制發(fā)動(dòng)機(jī)沿X軸和Y軸運(yùn)動(dòng)的，無論是軟件還是操作

12、工，在多組脈沖作用下均顯示錯(cuò)誤結(jié)果。電機(jī)轉(zhuǎn)速和轉(zhuǎn)矩的百分比由電動(dòng)機(jī)在任何時(shí)間供給。位置誤差在這里按定義之間的不同來進(jìn)行編輯并取得一定位置。 4 系統(tǒng)模型 數(shù)學(xué)模型的完整建立是由組成伺服控制的XY工作臺(tái)、切削條件等等。也是本節(jié)所要介紹的。XY工作臺(tái)是由裝有PCI插槽的電腦控制的，它的所有的計(jì)算需要工作臺(tái)沿確定的路徑而離開電腦處理器的時(shí)間做其他工作的過程。該軟件是由松下來研究發(fā)展的，以便于在線監(jiān)測(cè)伺服電機(jī)。 該元素的伺服系統(tǒng)包括電機(jī)、驅(qū)動(dòng)器、編碼器和控制器等，并在圖3顯示出來了，而完整的模型在圖4顯示，充分顧及到機(jī)械成分、切削力和剛度。 5 結(jié)果 在仿真的基礎(chǔ)上進(jìn)行模擬輸出如圖4所示，在

13、進(jìn)行的試驗(yàn)中，立銑刀應(yīng)符合以下規(guī)格：高速鋼刀具的直徑為12毫米，螺旋角刀具直徑為30，耙角工具直徑為11，工件材料則包括鋁和有機(jī)玻璃。在實(shí)驗(yàn)中，參數(shù)的不同則視進(jìn)給和切削深度而定。以每分鐘300毫米的進(jìn)給速度和2毫米的切削深度切割圓形槽樣的有機(jī)玻璃塊時(shí)，得出的加工路線如圖5所示。當(dāng)切削直槽時(shí)。錯(cuò)誤也需要衡量，也可能觀察不到太大的變化。所以這種類型對(duì)定位精度和進(jìn)給率可能沒有太大的影響。在切削直槽或圓槽時(shí)。降低進(jìn)給速度來減少誤差。 另一方面，錯(cuò)誤也出自如圖6所示的脈沖模型上，如果切削條件仍然與圖5那樣，則誤差范圍有所變化，他們是相似的。因此，數(shù)學(xué)模型代表著一個(gè)現(xiàn)實(shí)模型應(yīng)用于端銑操作的銑床上。 6

14、 結(jié)論 在本文提出了數(shù)學(xué)模型為端銑操作，這是結(jié)合仿真模型的伺服裝置來控制XY工作臺(tái)的。這是在實(shí)驗(yàn)初建成的，在真正的端銑切削加工中，它們都附著在現(xiàn)有的XY工作臺(tái)上。在編程和完成定位時(shí)，定位誤差是不同的。無論是從仿真模擬還是實(shí)驗(yàn)設(shè)定，都是為了獲得表。結(jié)果配合密切，正如在圖5與圖6所顯示的那樣。因此，在沒有做出真正的原型時(shí)，這樣的一個(gè)數(shù)學(xué)模型是有用的業(yè)績(jī)考核的一種新的設(shè)計(jì)，不過這樣即費(fèi)時(shí)且費(fèi)用昂貴。因此，無論是時(shí)間還是投資上，把一個(gè)新產(chǎn)品投入市場(chǎng)將引起激烈的競(jìng)爭(zhēng)。因此，在設(shè)計(jì)者中機(jī)電一體化的設(shè)計(jì)研究已經(jīng)被越來越多的人所接受。 7 一種新的制造技術(shù)----采用高速銑削 與一些好處的超高速銑削的方

15、法相比，傳統(tǒng)的銑可列為如下：增加切割速度，切割動(dòng)力和芯片體積，改善表面質(zhì)量。由于較低水平負(fù)載的工具和機(jī)床工具的熱量從切削區(qū)傳遞給晶片，是為了減少切削力而確保更好的精度，使工件溫度相對(duì)較低，從而減少了加工時(shí)間和加工費(fèi)用。很多時(shí)候，與傳統(tǒng)方法相比高速加工被認(rèn)為是一種由于高的切割速度而提高了生產(chǎn)率。它很少?gòu)?qiáng)調(diào)提高精度和更好的表面光潔度能提高產(chǎn)品質(zhì)量。 這項(xiàng)研究主要是由赫爾辛基科技大學(xué)和芬蘭的VTT技術(shù)研究中心來證明的，他們?yōu)椴煌愋偷牟牧虾彤a(chǎn)品測(cè)試是否適合高速切削。結(jié)果由HUT和VTT密切合作共同研究工業(yè)狀況來證實(shí)的。這項(xiàng)測(cè)試是對(duì)7200個(gè)垂直型加工中心海事處進(jìn)行研究證實(shí)的。其主軸是裝有深溝球軸承

16、，并能達(dá)到最高時(shí)速每分鐘4500轉(zhuǎn)，功率為5千瓦，X軸和Y軸最大進(jìn)給速度為每分鐘24米，Z軸最大進(jìn)給速度為每分鐘20米，數(shù)值控制選擇的是海德漢跨國(guó)公司的415. 耐磨性的刀具材料已被視為是限制切削速度的最重要的因素，高速鋼和涂層由于他們低的耐磨性已經(jīng)證實(shí)了我們的研究測(cè)試。高切削速度的硬質(zhì)合金的刀具壽命眾所周知是短的。不過，它們可用于加工軟材料，金屬陶瓷是被提供的整理的鋼。像立方氮化硼和聚晶金剛石這種超硬刀具材料，自然是被視為屬于改集團(tuán)的高速加工刀具材料。 該刀具適用于高速銑削，并可分為單銑和多銑。在我們這個(gè)領(lǐng)域的活動(dòng)中，我們的實(shí)驗(yàn)室還包括了制造業(yè)的復(fù)雜工件，如制造模具等。在那個(gè)領(lǐng)域，主要應(yīng)

17、用于固體銑刀。根據(jù)我們的經(jīng)驗(yàn)，高速加工的刀具都具有標(biāo)準(zhǔn)的幾何形狀。 應(yīng)用最廣的高速銑削加工是加工鋼材，因?yàn)樗麄兪窃诠こ讨袘?yīng)用最廣泛的材料。無論是工件中冷點(diǎn)、熱點(diǎn)和塑料模具鋼，它們?cè)谕瓿捎不癄顟B(tài)后會(huì)得到許多鋼材。采用高速銑削也可用于加工淬硬鋼。它通常用于在整理模具溶洞中作代替放電操作。立方氮化硼工具也通常被使用，主要是因?yàn)樗鼈冇泻芏鄡?yōu)點(diǎn)，例如它給出了一個(gè)替代碳化物。 這個(gè)問題涉及到由于缺乏有關(guān)切削參數(shù)為硬質(zhì)材料的參數(shù)方面的知識(shí)，使得超高速銑削鋼已不能勝任工具的耐磨性。刀具材料和刀具幾何形狀的發(fā)展將使之采用高速銑削不同的鋼材的調(diào)查可能履行。甚至在一定的鍛煉條件下使用高合金工具鋼。 Mec

18、hatronics approach 1 CNC machine tools popular science knowledge Digital control machine tools is the digital information in the form of code (programming instructions), the control tool given by the working procedures, velocity and trajectory of the automatic processing machine, or CNC machine t

19、ools. NC machine tool with a wide range of adaptability, processing only when the object changes need to change the procedures for the importation of instruction; processing performance than the general automatic machine tools, precision machining can be complicated surface, thus suitable for proces

20、sing small quantities, modified frequent, high-precision , The shape and the more complicated parts, and access to good economic results. With the development of numerical control technology, the use of CNC machine tools increasing varieties, lathes, milling machines, boring machine, drilling, grin

21、ding machines, machine tools and processing gear EDM machine, and so on. There is also the tool change automatically, with a multi-card processing operations of the processing centres, turning centres and so on. 1948, the United States to accept the U.S. Air Force commissioned by the Parsons Corpor

22、ation, the outline of the development model of aircraft propeller blades of the processing equipment. As example of complex and varied forms, high-precision, difficult to adapt to ordinary processing equipment, therefore proposed the idea of computer-controlled machine tools. 1949, the company in th

23、e U.S. Massachusetts Institute of Technology Research servo institutions, with the assistance of CNC machine tools began research and trial production in 1952 by the first successful large-scale copying of vertical milling machine converted the 3-D CNC milling machine, Soon start production. At tha

24、t time, the NC devices using tube components, size, is expensive, only a few in the aviation industry and other sectors with special needs for processing of complex components; 1959, made a transistor components and printed circuit boards, NC Entered a second-generation devices, reducing size, cost

25、has decreased in 1960 after a relatively simple and economic point of control NC drilling machine, CNC milling machine and line control by rapid development so that the NC machine tools in the machine manufacturing industry Gradually promote the various departments. In order to ensure a great machi

26、ne to process performance and ability to work for stability, structural design of CNC machine tools are characterized by sufficient rigidity, accuracy, anti-vibration, heat and maintain the stability and accuracy. Feed the mechanical transmission systems linked by ball screw, screw and non-static sp

27、ace gear, so as to minimize reverse gap. Machine tools used by motorized plastic rails, rolling or static guide rails to enhance the smooth movement of low-speed and movement when there is no creeping phenomenon. As a result of a wide speed range of feed-speed servo motor and the main motor, you ca

28、n not drive or less used and Gear Shift, which simplifies the machine's drive mechanism. Paixie facilitate the distribution of machine tools and parts handling, with automatic part of NC machine tools and auto parts Paixie exchange device. Most of CNC machine tools used with the microprocessor PLC,

29、strong, to replace the large number of counters in the relay, raising the machine-control, reliability and flexibility. With micro-electronics technology, computer technology and software technology is developing rapidly, the NC machine tool control system at the growing tendency of small-scale and

30、 multi-functional, have improved self-diagnostic features, reliability and greatly improve the system itself will generally NC Automatic programming. The type of CNC machine tools the future will be more diversified, multi-processing operations on the more and more varieties of NC machine tools, las

31、er processing technology will be implemented in cutting machine tools, thereby increasing the number of processes on the scope of the NC machine tool automation Further improve the level and a variety of monitoring, thus forming a flexible manufacturing unit, makes it easy to incorporate highly auto

32、mated flexible manufacturing systems. It is well known, a machine basic constitution including machine, transmission part, and execution part and control section. Transmission part is the overwhelming majority machine essential important constituent. From machine to working machine partial speed ch

33、anges, change heading, change mode of motion, power and movement transmission assignment and so on function. All is completes by the transmission device. In some machines (for example machine, automobile) center the transmission device occupies the entire machine majority, therefore the machine oper

34、ating performance and the operation cost are decided are partial (transmission device) to the transmission the fit and unfit quality in the very great degree. Therefore, in order to adapt the market to the mechanical product request enhances the transmission device the design level to have the vital

35、 significance. Since long ago, our country when design mechanical product, generally continues to use traditional the design method, the mechanical product design is the complex process which a morbid state structure, repeatedly iterates, costs the designer massive time and the energy, therefore,

36、regardless of by far could not satisfy user's request from the design performance and the design speed, has formed the advanced product request and in backwardness design method contradiction. At the same time, market competition intensifying, also requests the product to face, the low cost, and the

37、 short cyclical direction high grade is developing RI. At present, in machinery commonly used transmission design method commonly used theoretical design law. It is the design which carries on according to the existing science and technology theory and the practice knowledge, therefore, the commonly

38、 used design calculation formula are many is carries on the theory inferential reasoning in under certain suppositions conditions, again introduces aeries of correction coefficient, but obtains half theory semi-rational formula. Calculates using these formulas time, needs to look up a series of rela

39、ted forms or the graph determined the correction coefficient and certain parameters, the process is troublesome time-consuming: The machine designing is a process in particular which unceasingly revises, unceasingly consummates. The innumerable facts proved that, the experienced outstanding designer

40、 often could compared to just leave the school gate, the similarly rich talent designer to design a better product by a quicker speed to come. The expert system technology can help us to realize the expert to design the experience the induction and the use, causes the experience the continuation and

41、 development had greatly surmounted” between the priests and disciples" space and time limit, thus greatly advanced the design quality and the efficiency enhancement, thus for causes the transmission the design to adapt in the product market demand, develops the mechanical drive to design the expert

42、 system, quickly causes the transmission design speed, the computation to be accurate, the plan optimizes into the inevitable tendency. 2 INTRODCUTION A mechatronics approach is developing a mathematical model for the end milling operations on a CNC milling machine to simulate its behavior, is

43、 taken up in this paper. The mathematical model of the servomotor controlled XY table, developed elsewhere, is integrated with the proposed model for the end milling operations. Simulations are performed using SIMULINK of MATLAB. An experimental set-up was built to perform end milling operation on a

44、n existing XY table. SIMULINK results are validated with the experimental results. Such mathematical models are useful for evaluation of a new design. Hence, the lead time and cost to bring a new design in the market will be drastically reduced. Mechatronics is a concept introduced in Japan in 1980

45、s. Even though people refer to any system having mechanical, electrical, electronics components, for example, washing machine,photocopiers, CNC machines, etc., as mechatronics systems, truly `mechatronics!ˉ is a design philosophy. In conventional design approach, components of a system are designed

46、by respective experts. For example, a mechanical engineer designs the mechanical components, whereas the electrical engineer designs the electrical components, and so on. Since every designer leaves certain factor of safety (FOS) due to the ignorance of the other fields, the overall FOS is large and

47、 the system becomes bulky and expensive. In mechatronics design approach, the whole system is treated as one by taking care of all the components, be it a mechanical, electrical or electronics. As a result overall factor of safety is small and, hence, the system’s size and cost are reduced. In t

48、his paper, the mechatronics approach to the study of end milling in a CNC machine is taken up to aid the process of new design of a CNC machine table. The study requires the model of the machining process. The characteristics of end milling lies in the regular sequence of individual cuts, correspond

49、ing to each successive tooth engagements. These cuts many times are strongly overlapped. To predict the instantaneous cutting forces, mechanistic theory (Fuh and Hwang, 1997) is used. The force model developed here takes the feed of table and rpm of cutter as input parameters and gives the instantan

50、eous force as output at different cutter flutes locations. Mechanical transmission elements of the XY table comprising of motor axes and ball screws are also considered. Since stiffness of the mechanical elements plays an important role in accuracy of machined parts they are also taken into account

51、in the mathematical model, whereas the models of the PMBLDC servo motors of the XY table are taken from Kataria and Mehta (2001). Based on these models, simulations are performed using SIMULINK of MATLAB. An attachment for the end milling operation is also designed and fabricated, which is attached

52、to the already available XY table for experimental verifications of some of the simulation results. 3 EXPERIMENTAL SET-UP The study of proposed end milling operation is assumed to be done in a CNC milling machine. In our study, end milling was carried out on an available XY table. So a frame was d

53、esigned and fabricated which supports motor and locates the spindle. Figure 1 shows the frame designed and fabricated to carryout the experiments, whereas Fig. 2 shows the photograph of the complete set-up. The spindle of the attachment is designed in such a way that its one end is connected with th

54、e AC induction motor shaft providing rotation, whereas the other end is connected to a drilling chuck which is modified to hold the end mill cutter . Fig. 1 End milling attachment 2.0 Spindle motor . Power requirements for end mill

55、ing are done as per the production technology handbook . Based on the power to cut Aluminum by an HSS tool, spindle motor is selected as: 220V, 1440RPM, 250W, single-phase AC induction motor. 2.1 Frame The horizontal link of the frame in the end mill attachment, as shown in Fig. 1, is the critica

56、l one as it supports the motor and the spindle against bending forces induced during cutting. This link is designed as simple supported beam. Link cross-section is chosen as: 35mm x 35mm, 3mm thickness, hollow. 2.2 Tool holding device In actual CNC milling machines, draw bar mechanism is used t

57、o secure the cutting tool. However, to keep the system simple, here a drilling chuck was modified to serve the purpose of holding the end mill cutter. 2.3 Bearing Bearing is fixed on the frame which houses the spindle. The forces coming on the spindle are predominantly of bending. So, bearings h

58、ave to withstand radial forces. Hence, the SKF deep groove ball bearings 6004 are selected. 2.4 Panaterm The system response was observed by using the software package PANATERM , whereas DMCterm is another software was used to communicate with the Galil DMC1822 controller card (Galil, 2000). D

59、MC1822 is a two-axis controller which controls the PMBLDC motors along X and Y axes. Both the software allow online monitoring of the driver, which show errors in terms of the number of pulses, motor RPM, and torque percentage supplied by the motors at any time instant. The positional errors are de

60、fined here as the difference between the programmed and achieved positions. 3 SYSTEM MODELLING The mathematical model of the complete set-up, comprising of the servo controlled XY table, cutting conditions, etc., is presented in this section. The controller of the XY table is mounted on the PCI

61、 slot of the PC, which does all the calculations necessary to move the table along a pre-determined path leaving computer processor time free to do other jobs. The software package PANATERM developed by Panasonic facilitates the online monitoring of the servomotors. The elements of servo system i

62、ncluding motor, driver, encoder and the controller are modelled and shown in Fig. 3, whereas the complete model is shown in Fig. 4 that takes care of the mechanical elements, cutting forces and stiffness . Fig. 3 Functional elements of the controller.

63、 Fig. 4 Complete SIMULINK (in MATLAB) model. 4 RESULTS Simulations are performed in SIMULINK based on the model shown in Fig. 4 and experiments were conducted using an end milling cutter with the following specifications: HSS tool with straight shank of diameter 12mm; Helix angle of too

64、l 30 ; Rake angle of the tool 11 . Work materials are considered as Aluminum and Perspex (polymethyl methalcralyte). For experiments, the parameters varied are feed and depth of cut. For the cutting of a circular slot on Perspex block at 300mm/min feed rate with 2mm depth of cut, errors obtained fr

65、om PANATERM are shown in Fig. 5. Errors were also measured while cutting straight slot but not much variations were observed. So the type of paths may not have much influence on the positional accuracy, whereas the feed rate has. Lowering the feed rate has reduced the variation of errors during str

66、aight or circular slots. On the hand, errors from the SIMULINK model is shown in Fig. 6, where the cutting conditions remained same as in Fig. 5. Note the range of error variations, which is similar, i.e., +/- .075mm. Hence, the mathematical model represents the a realistic model for the end milling operation on a milling machine. 5 CONCLUSIONS Mathematical model for the end milling operation is proposed in this paper, which is integrated w