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本科生畢業(yè)論文(設計)開題報告
論文題目:三坐標數(shù)控銑床設計
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一. 數(shù)控機床的產(chǎn)生與發(fā)展
科學技術的不斷發(fā)展,對機械產(chǎn)品的質(zhì)量和生產(chǎn)率提出了越來越高要求。機械加工工藝過程的自動化是實現(xiàn)上述要求的最主要的措施之一。它不僅提高產(chǎn)品的質(zhì)量、提高生產(chǎn)效率、降低生產(chǎn)成本、還能夠大大改善工人的勞動條件。
大批量的自動化生產(chǎn)廣泛采用自動機床、組合機床和專用機床以及專用自動生產(chǎn)線,實行多刀、多工位同時加工,以達到高效率和高自動化。但這些都屬于剛性自動化,在面對小批量生產(chǎn)時并不是適用,因為小批量生產(chǎn)需要經(jīng)常變化產(chǎn)品的種類,這就要求生產(chǎn)線具有柔性。而從某種程度上說,數(shù)控機床的出現(xiàn)正是很大的滿足了這一要求。
1952年,美國麻省理工學院成功的研制出一套三坐標聯(lián)動,利用脈動乘法器原理的實驗性數(shù)控系統(tǒng),并把它裝在一臺立式銑床上。當時用的電子元件是電子管,這就是世界上的第一臺數(shù)控機床。1959年,數(shù)控裝置中廣泛采用電子管和印刷電路板,從而跨入數(shù)控的第二代。1965年,出現(xiàn)了小規(guī)模集成電路,由于它體積小、功耗低,使數(shù)控系統(tǒng)的可靠性得以進一步提高,從此數(shù)控發(fā)展到第三代。1970年,在美國芝加哥國際機床展覽會上首次展出的數(shù)控系統(tǒng)采用計算機數(shù)控系統(tǒng)的機床,這便是數(shù)控的第四代。1974年,出現(xiàn)了第五代數(shù)控系統(tǒng)(MNC微處理機控制系統(tǒng))。
我國是從1958年開始研制數(shù)控技術的,一直到60年代中期處于研制、開發(fā)時期。當時,一些高等院校、科研單位研制出實驗樣機,開發(fā)也是從電子管開始的。1965年國內(nèi)開始研制晶體管數(shù)控技術。從70年代開始,數(shù)控技術在車、銑、鉆、鏜、磨、齒輪加工等領域全面展開,數(shù)控加工中心在上海、北京研制成功。在這一時期,數(shù)控線切割機床由于結果簡單、使用方便、價格低廉,在模具加工中得到了推廣。80年代我國數(shù)控機床有了新的發(fā)展。90年代以及接下來主要是向高檔數(shù)控機床發(fā)展
數(shù)控技術是近代發(fā)展起來的一種自動控制技術,是用數(shù)字化信號對機床運動及其加工過程進行控制的一種方法。目前,在工業(yè)發(fā)達國家,無論在國防工業(yè)或民用工業(yè),數(shù)控機床的應用均已相當普遍。數(shù)控機床已不在局限用來加工單件、小批以及形狀復雜的零件。
數(shù)控加工中心機床,它是在一般數(shù)控鏜銑床上加裝刀庫和自動換刀裝置??梢赃B續(xù)地對零件進行各加工面的銑、鉆、鉸、鏜以及攻絲的加工。減少了機床的占地面積,壓縮了半成品的庫存量,減少工序間的輔助時間,有效地提高了生產(chǎn)率。
可以預見,高級自動化技術將進一步證明數(shù)控機床的價值,并且正在更為廣闊的開拓著數(shù)控機床的應用領域。
二. 數(shù)控銑床的工作原理
用數(shù)控銑床加工零件時,首先應編制該零件的加工程序,這是數(shù)控銑床的工作指令。將加工程序輸入數(shù)控裝置,再由數(shù)控裝置控制機床主運動的變速、啟動、停止、進給運動的方向、速度和位移量,以及工件裝夾和冷卻潤滑的開關等動作,使刀具與被加工零件以及其它輔助裝置嚴格按照加工工序規(guī)定的順序、運動軌跡加工出符合要求的零件。
三. 數(shù)控銑床的組成
數(shù)控銑床的組成:機床、數(shù)控裝置、控制介質(zhì)、伺服系統(tǒng)、測量裝置等組成。
機床:三坐標數(shù)控磨床應具有更好的剛性和抗振性,因此床身采用密封式箱型結構,在床身底內(nèi)腔填充泥芯和混凝土等阻尼材料,當發(fā)生振動時,利用阻尼材料之間的相對摩擦耗散振動能量。
數(shù)控裝置:數(shù)控裝置是數(shù)控機床的核心,是高技術密集型產(chǎn)品。它的功能是接受輸入裝置輸入的加工信息,經(jīng)過數(shù)控裝置的系統(tǒng)軟件對代碼進行處理后,輸入相應的指令脈沖,驅(qū)動伺服系統(tǒng),來控制機床的各個運動部件按規(guī)定的要求實現(xiàn)各個運動。
控制介質(zhì):用于記載各種加工信息的載體,以控制機床的運動,實現(xiàn)零件的加工。數(shù)控介質(zhì)有穿孔帶、穿孔卡、磁帶及磁盤等,也可通過通信接口直接輸入所需各種信息。三坐標數(shù)控銑床采用通信接口直接輸入所需各種信息。用鍵盤將加工程序直接鍵入,并且可在數(shù)碼顯示器或CRT顯示器上顯示出來。
伺服系統(tǒng):由伺服電動機和伺服驅(qū)動裝置組成,是數(shù)控系統(tǒng)的執(zhí)行部分。作用是把來自數(shù)控裝置的各種指令轉(zhuǎn)換成機床移動部件的運動速度、運動方向和位移量。伺服系統(tǒng)要求有良好的快速響應性能,進給速度范圍要大,靈敏而準確的跟蹤指令功能和轉(zhuǎn)速,在較大的范圍內(nèi)要求有良好的工作穩(wěn)定性。此數(shù)控銑床的驅(qū)動元件為交流三相異步電動機。
測量裝置:是將床身的實際位置、速度等參數(shù)轉(zhuǎn)換成電信號反饋回數(shù)控裝置。以校核執(zhí)行部件實際運動速度、方向和位移量,并使之與加工指令相一致。
四. 設計題目及技術要求
設計題目是三坐標數(shù)控銑床設計。從總體布局和結構形式,與普通銑床相似,主要還是由床身,主軸箱,刀架,進給系統(tǒng),液壓、冷卻、潤滑系統(tǒng)等部分組成。但是,由于動力源采用了交流伺服電機,控制系統(tǒng)實現(xiàn)了CNC,所以,使得主運動和進給系統(tǒng)機械結構大大簡化。尤其是進給系統(tǒng),與普通銑床的進給系統(tǒng)有質(zhì)的區(qū)別,沒有傳統(tǒng)的進給箱,板箱和掛輪架,而是直接由伺服電機通過滾球絲杠驅(qū)動溜板和刀架,實現(xiàn)進給運動。
主要設計要求:三坐標數(shù)控銑床,進給精度0.01mm,X、Y、Z坐標進給速度2m/min,X、Y、行程300mm,Z行程250mm,工作臺尺寸420×300mm。
五. 數(shù)控銑床各組成部分的分析
1. X、Y工作臺
X、Y工作臺的組成:X、Y工作平臺傳動機構;X向齒輪減速和滾珠絲杠傳動方向(Y向和X向相同);驅(qū)動機構:X、Y向兩個電機。
X、Y工作臺的工作原理:通過控制X、Y向電機驅(qū)動傳動機構,從而帶動X、Y工作平臺沿X、Y向運動。
2. 主軸
主軸部件包括主軸軸承、傳動件和相應的緊固件。主軸的端部是標準的。傳動件如齒輪、帶輪等與一般的機械零件相同。機床主軸部件,三個方向的進給及其它部件滾動軸承,均采用潤滑脂潤滑。
3. 導軌
由運動和承導件組成。運動件:需要做直線運動的零部件。承導件:用于支承并限制運動件,使其只能按給定的要求和規(guī)定的方向作直線運動。設計中可采用滑動導軌,對導軌要求有以下幾點:
(1) 要有一定的導向精度。
(2) 要有良好的耐磨性。
(3) 要有足夠的剛度。
(4) 有減小熱變形影響。
(5) 要使運動輕便平穩(wěn)。
(6) 要有一定的工藝性。
主要用來支承和引導部件沿一定的軋道運動。要求導向精度高,耐磨性能好,足夠的剛度。本設計采用塑料導軌,鑲粘塑料導軌已廣泛用于數(shù)控機床。其摩擦系數(shù)小,且動、靜摩擦差很小,能防止低速爬行現(xiàn)象;耐磨性、抗撕傷能力強;加工性和化學穩(wěn)定性好;工藝簡單,成本底;并有良好的自潤滑性和抗震性。塑料導軌多與淬硬剛導軌相配使用。
滑動導軌間隙的調(diào)整:采相應的用刮、磨結合面或加墊片的方法以獲得相應的間隙;鑲條調(diào)整,這是側向間隙常用的調(diào)整方法,鑲條有直鑲條和斜鑲條兩種。采用矩形導軌,這種導軌的特點是結構簡單,制造、檢驗和修理較易,新導軌制造精度高,但導軌經(jīng)磨損后不能自動補償,導向性不如三角形導軌好。
三坐標數(shù)控銑床采用貼塑導軌,這是一種金屬對塑料的摩擦形式。屬于滑動摩擦導軌,導軌一滑移面上貼有一層抗磨軟帶,導軌的另一滑移面上貼為淬火磨削面,軟帶是以聚四氟乙烯為基材,添加合金粉和高氧化物的高分子復合材料。塑料導軌剛性好、動靜摩擦系數(shù)差值小、耐磨性好、無爬行、抗振性好、化學的穩(wěn)定性好、維護修理方便、經(jīng)濟性好。
塑料導軌和其它導軌相比,有以下特點:
(1) 摩擦系數(shù)低而穩(wěn)定性比鑄鐵導軌低一個數(shù)量級;
(2) 動靜摩擦系數(shù)相近,運動平穩(wěn)性和爬行性能較鑄鐵導軌副好;
(3) 吸收振動具有良好的阻尼性,優(yōu)于接觸剛度較低的滾動導軌和易于飄浮的靜壓導軌;
(4) 耐磨性好,有自身潤滑作用,無潤滑油也能工作,灰塵磨粒的遷入性好;
(5) 化學的穩(wěn)定性好,耐高、低溫、耐強酸強堿、強氟化劑及各種有機溶劑;
(6) 維護修理方便,軟帶磨損后更易更換;
(7) 經(jīng)濟性好、結構簡單、成本低,約為滾動導軌成本的1/120。三成復合材料DU 導軌板成本的1/4。
三個方向的導軌副、滾珠絲杠副由自動間隙潤滑油泵進行定時潤滑,潤滑油泵安裝在立柱側面,通過分油器將潤滑油分送到各潤滑點上。
4. 進給裝置
三坐標數(shù)控銑床的進給運動是數(shù)字控制的直接對象,不論點位控制還是連續(xù)控制,被加工工件的最后坐標精度和輪廓精度都受到進給運動的傳動精度、靈敏度和穩(wěn)定性的影響。為此,要注意以下三點進給運動要求:
(1) 減少運動件的摩擦力。進給系統(tǒng)雖有許多元件,但摩擦阻力主要來自絲杠和導軌。絲杠和導軌結構的滾動化是減少摩擦的重要措施之一。
(2) 提高傳動精度和剛度。在進給系統(tǒng)中滾珠絲杠和支承結構是決定其傳動精度和剛度的主要部件,因此,必須首先保證它們的加工精度。
(3) 減少運動慣量。進給系統(tǒng)中每個元件的慣量對伺服機構的啟動和制動特性都有直接的影響。尤其是處于高速運轉(zhuǎn)的零件,其慣性的影響更大。
5. 滾動絲杠
滾珠絲杠螺母副:在具有螺旋槽的絲杠螺母間裝有滾珠作為中間傳動元件,以減少摩擦。當絲杠與螺母相對運動時,滾珠沿螺旋槽向前滾動,在絲杠上滾過數(shù)圈以后通過回程引導裝置,逐個地又滾回到絲杠與螺母之間,構成一個閉和回路。它的優(yōu)點是:
(1) 摩擦系數(shù)小,傳動效率高,η可達0.92-0.96,所需傳動轉(zhuǎn)矩小。
(2) 靈敏度高,傳動平穩(wěn),不易產(chǎn)生爬行,隨動精度和定位精度高。
(3) 磨損小,壽命長,精度保持性好。
(4) 可通過預緊和間隙消除措施提高軸向剛度和反向精度。
(5) 運動具有可逆性,不僅可以將旋轉(zhuǎn)運動。
6. 進給伺服系統(tǒng)
進給伺服系統(tǒng)的組成:有驅(qū)動控制單元、驅(qū)動元件、機械傳動部件、執(zhí)行件和檢測反饋環(huán)節(jié)等組成。驅(qū)動控制單元和驅(qū)動元件組成伺服驅(qū)動系統(tǒng);檢測元件與反饋電路組成檢測裝置亦稱檢測系統(tǒng)。進給伺服系統(tǒng)中采用的驅(qū)動裝置為直流伺服電機。
7. 微處理器
用來集中控制,分時處理數(shù)控系統(tǒng)的各項任務。單微處理器機構的基本組成包括:微處理器和總線、存儲I/O接口、MDI/CRT接口、位置控制器、PC。微機控制系統(tǒng)的硬件設計主要就是上述幾個部分的具體設計。
六 參考資料
1.數(shù)控機床設計手冊;
2.機械設計手冊;
3.機電傳動控制;
4.標準件手冊。
5. 機電一體化設計手冊
七 進度計劃
第一階段:完成所選課程,完成英文翻譯。
第二階段:完成畢業(yè)設計的總體規(guī)劃,查閱相關資料。
第三階段: 完成X-Y工作臺設計及相關計算。
第四階段: 完成磨頭設計。
第五階段: 完成控制系統(tǒng)設計。
第六階段: 撰寫畢業(yè)設計說明書,出圖,準備答辯。
英 文 翻 譯
INTRODUCTION TO MECHATRONICS
1: What Is "Mechatronics"?
"Michatronics" is a term coined by the Japanese to describe the integration of mechanical
and electronics engineering. The concept may seem to be anything but new ,since we can all
look around us and see a myriad of products that utilize both mechanical and electronic dis-
cipplines. Mechatronics,however ,specifically refers to a multidisciplined ,integrated approach
to product and manufacturing system design .It represents the next generation of machines,
robots ,and smart mechanisms necessary for carrying out work in a variety of environments-
primarily ,factory automation ,office automation ,and home automation as show in Figure 1.
By both implication and application ,mechatronics represents a new level of integration
for advanced manufacturing technology and processes .The intent is to force a multidisciplinary
approach to these syetems as well as to reemphasize the role of process understanding and
control .This mechatronic approach is currently speeding up the already-rapid Japanese process
for trasforming ideas into products .
Currently ,mechatronics describes the Japanese practice of useing fully intefrated teams
of product designers ,manufactring, purchasing, and marketing personnel acting in concert with
each other to design both the product and the manufacturing syestem.
The Japanese recognized that the future in producdtion innovation would belong to those who
learned how to optimize the marriage beween eletronic and mechanical systems.They realized,in
particular ,that the need for this optimizatong would be most intense in application of advanced manufacturing and production systems where artificial intelligence ,expert
systems ,smart robots, and advanced manufacturing technology systems would create the next
generation of tools to be used in the factory of the future.
From the very beginnings of recorded time ,mechanical systems have found their way into every
aspect of our society .Our simplest mechanisms ,such as gears ,pulleys, springs,and wheeles.
have provided the basis for our tools .Our electronics technology,on the other hand ,is completely
twentieth-century ,all of it created within the past 75 years.
Until now ,electronics were included to enhance mechanical systems' performance ,but the
emphasis remained on the mechanical product .There had never been any master plan on how the
integration would be done .In the past ,it had been done on a case -by-case basis .More recently
,however,because of the overwhelming advances in the world of electronics and its capability
to physically simplify mechanical configurations ,the technical community began to reassess
the marriage between these two disciplines.
The most obvious trend in the direction of mechatronic innovation can be observed in the
automobile industry .There was atime when a car was primarily a mechanical marvel with a
few electronic appendages.
First came the starter motor ,and then the generator ,each making the original product a bit
better than it was before .Then came solid-state electronics,and suddenly the mechanical marvel
became an electro-mechanical marvel .Today's machine is controlled by microprocessors ,built by
robots ,and fault-an-alyzed by a computer connected to its "external interface connector".
Automotive mechanical engineers are no longer the masters of their creations.
The process that describes the evolution of the autimibile is somewhat typical of other
productds in our society.Electronics has repeatedly improved the performance of mechanical
systems ,but that innovation has been more by serendipity than by design .And that is the essence
of mechatronica the preplanned application of ,and the efficient integration of,mechanical
and electronics technology to create an optimum product.
A recent U.S. Department of Commerce report entitled "JTECH Panel Report on Mechatronics
in Japan"compared U.S and Japanese research and development trends in specific areas of mechatronics
technology.Except for afew areas ,the technology necessary to accomplish the development of
the next generation of systems embodying the principles of mechatronics is fully within the
technological reach of the Japanede .
Comparisons were made in three categories :basic research ,asvanced development, and product
implementation.Except for machine vision and software ,Japanese basic research was comparable
to the United States,with the Japanese closing in fase on macchine vision system technology.
Japanese artificial intelligence research is falling behind ,primarily because the Japanese do
not consider it an essential ingredient of their future systems ,they appear capable of closing
even that gap,if required .In the advanced development and product implementation areas,Japan
is equal to or better than the United States,and is continuing to pull ahead at this time .
The Department of Commerce report concleuded that Japan is maintaining itsposition and is
in some cases gaining ground over the United States in the application of mechatronics .Their
progress in mechatrinics is important because it addresses the very means for next generation
of data -driven advanced design and manufacturing technology. In fact ,the Department of Commerce
repert cincludes that this has created a regenrative effect on Japan's manufacturing industries.
TO clese the gap ,we will need to go much further than creating new tools .If we accept
the fact that mechanical systems optimally coupled with eletronics components will be the wave
of the future ,then we must also understand that the pipple effect will be felt all the way back
to the university,where we now keep the two disciplines of mechanics and eletronics separated and
allow them to meet only in occasional overview sessions .New curricula must be create fir a new
hybrid engineer a mechatronics engineer .Only then can we be assured that future generations
of product designers and manufactuiing engineers will full seek excellence in these new techniques.
We need to rethink our present day approach of separating our engineering staffs both and
from each other and from the producting engineers .Living together and communicating individual
knowledge will be the key to optimum designs and new product development .
The definition of mechatronics is much more significant than its combined words imply .
It can physically turn engineering and manufacturing upside down. It will change the way we
design and produce the next generating of high technology products.The nation that fully implements
the rediments of mechatronics and vigorousely pursues it will lead the word to a new generation
of technology innovation with all its profound implications.
2.Benefits Of Mechatronics
Mechatronics may sound like utopia to many product and manufacturing managers it is often presented as the solution to nearly all of the problems in manufacturing . In particular ,it promises to increase productivity in the factory dramatically.Design changes are easy with extensive use of mechatronic elements such as CAD; CAP and MIS systems help in scheduling ; and flexible manufacturing systems ,computer-aided design ,and computer –integrated manufacturing equipment cut turnaround time for manufacturing .These subsystems minimize production costs and greatlu increase equipment utilization .Connections from CAE,CAD, and CAM help create designs that are economical to manufacture ;cintrol and communications are improved,with minimal paper flow; and CAM equipment minimizes time loss due to setup and materials handling.
Many companies that make extensive use of computers view their factories as examples of mechateonic concepes, but on close wxamination their integration is horizontal-in the manufacturing area only –or at best includes primarily manufacturing and managemengt .General Electric ,as part of its effort to become a major bendor of factory automation systems ,including its Erie Locomotive Plant, its Scjenectady Steam Turbine Plant, and its Charlottesville Controls Manufacturing Division. The primary benefits of mechatronics, with an emphasis on advanced manufacturing technology and factory automation ,are summarized below.
High Capitial Equipment Utilization
Typically , the throughput for a set of machines in a mechatronics system will be up to three times that for the same machines in a stand-alone job shop environment . The mechatronic system achieves high efficiency by having the computer schedule every part to a machine as soon as it is free , simultaneously moving the part on the automated material handling system and downloading the appropriate computer program to the machine . In addition , the part arrives at a machine already fixtured on a pallet (this is done at a separate work station )so that the machine does not have to wait while the part is set up .
Reduced Capital Equipment Costs
The high utilization of eqipment results in the need for fewer machines in the mechatronic system to do the same work load as in a conventional systenm . Reductions of 3:1 are common when replaceing machining centers in a job-shop situation with a mechatronic system.
Reduced Direct Labor Costs
Since each machine is completely under computer control ,full-time oversight is not repaired . Direct labor can be reduced to the less skilled personnel who fixture and defixture the parts at the work station ,and a machinist to oversee or repair the work stations ,plus the system supervisor . While the fixturing personnel in mechatronic environments require less advanced skills than corresponding workers in conventional factories , labor cost reduction is somewhat offset by the need for computing and other skills which may not be required in traditional workplaces.
Reduced Work-in –Process Inventory and Lead Time
The reduction of work –in-process in a mechatronic system is quite dramatic when compared to a job-shop environment . Reductions of 80 percent have been reported at some installations and may be attributed to a variety of factors which reduce the time a part waits for metal-cutting operations. These factors include concentration of all the equipment required to produce part into a small area ;reduction in the number of fixtures required ;reduction in the number of machines a part must travel through because processes are combined in work cells ; and efficient computer scheduling of parts batched into and within the mechatronic system.
Responsiveness to Changing Production Requirements
A mechatronicsystem has the inherent flexibility to manufacture different products as the demands of the demands of the marketplace change or as engineering design changes are introduced .Furthermore , required spare part production can be mixed into regular runs without significantly disrupting the normal mechatronic system production activities.
Abulity to Maintain Prodution
Many mechatronic system are designed to degrade gracefully when one or more machines fail . This is accomplished by incorporating redundant machining capability and a material handling system that allows failed machines to be bypassed . Thus , throughput is maintained at a reduced rate.
High Product Quality
A sometimes-overlooked advantage of a mechatronic system , especially when compare to machines that have not been federated into a cooperative system , is improve product quality . The basic integration of product design characteristics with production capability ,the high level of automation , the reduction in the munber of fixtures , and greater attention to part/machine alignment all result in a good individual part quality and excellent consistency from one workpiece to another ,further resulting in greatly reduced costs of rework.
Operational Flexibility
Operational flexibility offers a significant increment of enhanced productivity . In some facilities , mechateonic system can run virtually unattended during the second and the third shifts . This nearly “unmanned “ mode of operation is currently the exception rather than the rule . It should , however, become increasingly common as better sensors and computer controls are developed to detect and handle unanticipated problems such as tool breakages and part-flow jams . In this operational mode , inspection ,fixturing , and maintenance can be performed during the first shift .
Capacity Flexibility
With correct planning for available floor space , a mechatronics system can be designed for low production volumes initially ;as demand increase , new machines can be added easily to provide the extra capacity required.
Mechatronic System Elements
This chapter provides a brief introduction to the mechatronic system concept and the system elements required to implement mechatronic technology . The stress is on factory automation ,whiche will serve as the foundation for mechatronic technology integration in office automation and home automation .
System Concept
Mechatronic production systems include all aspects of product design , manufacturing , and plant management , in a coordinated data-driven computer-as-sisted system .But unlike any other process before , they will also include the operationts that are the involed in defining the product a plant is to manufacture .It is precisely here that the Japanese have excelled ,making many American firms take notice and wonder why their share of the market is disappearing.
A close inspection of the process would receal that the Japanese had created new products that were so much attuned to the using public that our statle products lacked luster in the market-place . They created a need for their products and did so by that age-old principle which states, “give the customer what he wants ,not what you think he wants .”
Sharing the design process with customer is an interesting process that , when considered as part of the mechatronic philosophy , becomes the prime mover for everything else that happens in factory automation.
There are three general groups of mechatronic functions , as shown in Figure 2: market needs analysis ,which results in user-oriented product design ; manufacture(both fabrication and assembly ) of products on the factory floor; and enlightened management of factory operations . The three general groups noted above ,stressing the need for inproved design , product manufacturing ,and enlightened management ,are not necessarily mutually exclusive . In fact , the goal of introducing mechatronics into these systems is to break down the barriers between them so that design and manufacturing system are inextricably linded . Howerer , the three categories are useful to frame the discussion , particularly since they correspond to the organization of a typical manufacturing firm.
漢語翻譯
機電一體化概述
1:何為機電一體化
機電一體化是日本人新造的術語,用來描述機械工程與電子工程的結合。機電一體化的念除了是個新的概念之外,還可以看成包含任何東西的概念,因為我們周圍有許許多多的數(shù)不清的產(chǎn)品都是機械和電子技術有機結合的產(chǎn)物。然而機電一體化特別指的是多學科相結合的產(chǎn)品設計和制造系統(tǒng)的方法,他代表著下一代的機器、機器人和靈敏的機械能夠在一系列不同的環(huán)境下進行工作。主要是:工廠自動化、辦公自動化、家庭自動化,如下圖1所示
同時應用機電一體化代表著一個新的層次上的先進生產(chǎn)技術和過程相結合。這就意味著把包含多種學科并且反復強調(diào)的方法應用于那些系統(tǒng),這與把理解和控制放在一個重要的地位上是一樣的。這種機械與電子技術相結合的方法使現(xiàn)今觀念轉(zhuǎn)變已經(jīng)比較快的日本更快的把技術應用于產(chǎn)品之中。
目前,機電一體化闡述了日本人使用充分結合的隊伍的實踐,這一隊伍包括產(chǎn)品設計者、制造人員、采購人員和銷售人員,他們相互一致行動,既設計產(chǎn)品又設計制造系統(tǒng)。
日本人承認在生產(chǎn)革命中未來將屬于知道怎樣使用電子系統(tǒng)和機械系統(tǒng)之間相結合的最好的人們,更特別的是他們意識到這種需要是先進生產(chǎn)技術和制造系統(tǒng)的優(yōu)化是最強烈的,譬如人工智能、專家系統(tǒng)、靈巧機器人。先進的制造系統(tǒng)能夠創(chuàng)造下一代將來能夠在工廠應用的工具。
迄今為止,機械系統(tǒng)已經(jīng)在我們社會各方面廣泛應用且存在,例如我們的一些簡單機械齒輪、彈簧、輪子都是我們?nèi)粘I畹幕竟ぞ摺T诹硪环矫嫖覀兊碾娮蛹夹g在20 世紀已經(jīng)在短短的75年內(nèi)就已經(jīng)相當?shù)陌l(fā)達了。
直到現(xiàn)在,電子技術從屬于機械系統(tǒng),并來增強機械系統(tǒng)的性能。但是重點仍然放在機械產(chǎn)品的生產(chǎn)上,從沒有把機械和電子相互結合。在過去,只是就事論事,最近由于世界上電子技術的不可抵擋的先進性,且能夠?qū)嶋H的簡化機械裝置。機械技術行業(yè)開始將電子技術與機械“聯(lián)姻”。
最直接的機電一體化改革體現(xiàn)在自動化工業(yè)。我們進入了一個嶄新的時代,一輛汽車是只有幾個電子元件就能控制的機器。
首先是起動器馬達,接著出現(xiàn)的是發(fā)電機。每一次都使產(chǎn)品有了新的進步,之后半導體電子元件(由集成塊、晶體管和二極管組成)的出現(xiàn)成為機械行業(yè)的奇跡?,F(xiàn)今的機器是由微處理器控制,由機器人生產(chǎn),故障分析由與外接口連接器連接的電腦控制,自動化機器引擎。電子技術已再三的改善了機械系統(tǒng)的性能。這是機電一體化的精華─機械技術和電子技術預先計劃應用和有效結合以創(chuàng)造一種最佳的產(chǎn)品。
美國貿(mào)易部最近的一篇題為“日本技術規(guī)則委員會關于機電一體化評論”的報告比較了美國和日本在機電一體化技術上的研究和發(fā)展。除了少數(shù)領域外,完成使機電一體化的原理具體化的下一代系統(tǒng)的研制所必須的技術完全在日本人所能及的范圍內(nèi)。
在下列三個方面作了比較:基礎研究、試樣樣品和產(chǎn)品實現(xiàn)三個方面。除了機械視覺系統(tǒng)和軟件系統(tǒng)外,日本的基礎研究與美國的是可以相比的,日本人在機器視覺系統(tǒng)(系統(tǒng)通過傳感、物體識別、圖象分析和解釋來確定物體的方位和形狀的能力,稱為機械視覺系統(tǒng))日本人工智能方面的研究比美國相對落后,主要是日本人不認為人工智能是與他們將來系統(tǒng)結合的關鍵。如果需要的話,他們甚至關閉且不研究人工智能。在試樣試品和產(chǎn)品實現(xiàn)方面,日本與美國持平,甚至超過美國,并在一段時間內(nèi)仍保持領先勢頭。
美國貿(mào)易部的報告總結出:日本仍然保持其地位,在一些情況下,對于機電一體化的應用仍勝于美國。他們在機電一體化方面的進步是非常重要的,因為它是下一代以數(shù)據(jù)為主導的設計及制造技術的重要手段。實際上,美國貿(mào)易部報告的結論會對日本的工業(yè)生產(chǎn)產(chǎn)生更深遠的影響。
為了縮小差距,我們不僅要制造新的工具,而且我們要走的路更遠。如果我們接受電子元件最佳結合的機械系統(tǒng)將是未來的浪潮。這一事實,那么我們一定能理解。這波紋效應一直到大學都能感覺到。在大學里我們把機械學和電子學這兩門學科分離,而且僅在偶然的綜合性課程中允許二者相遇?,F(xiàn)在的課程必須能夠創(chuàng)造新的混合型的工程師──機電一體化工程師。只有這樣,我們才能保證將來下一代的產(chǎn)品設計者和制造工程師將在新的技術領域有出色的表現(xiàn)。
我們必須需要重新思考一下我們現(xiàn)代的劃分我們機電一體化工程師成員的方法,既要彼此互相區(qū)別,而又要與產(chǎn)品工程師相互區(qū)別。居住在一起,個人之間相互交流在產(chǎn)品將產(chǎn)生一種復雜的效應。最大化的相互作用是優(yōu)化設計和新產(chǎn)品開發(fā)的關鍵。
機電一體化的定義的重要性不在于它是詞語的簡單組合,他把工程技術和制造技術相互結合,他會改變我們設計和生產(chǎn)下一代高科技產(chǎn)品的方式,充分為機電一體化提供基礎,并強有利的推行機電一體化的國家將把世界導向一場具有深遠意義的新一代技術革命。
2:機電一體化的優(yōu)勢
機電一體化對于許多產(chǎn)品和制造者聽起來似乎是近乎理想的完美境界,因為機電一體化幾乎能解決生產(chǎn)制造中的所有問題,更特別的是,他很有可能顯著的提高工廠產(chǎn)品的產(chǎn)量。廣泛的利用機電一體化組成部分例如CAD(計算機輔助設計)、CAP(計算機輔助計劃)和MIS(管理信息系統(tǒng))幫助的編制進度。并且柔性制造系統(tǒng)、計算機輔助設計、計算機集成制造設備,可以大大的降低生產(chǎn)制造的工作周期,這子系統(tǒng)降低產(chǎn)品成本和提高設備的利用率,與CAE(計算機輔助工程)、CAD、CAM(計算機輔助制造)相結合的機電一體化能創(chuàng)造更經(jīng)濟的產(chǎn)品,利用控制和聯(lián)絡的提高,降低圖紙數(shù)量,并且CAM設備減少了安裝和控制機器的時間。
許多公司更廣泛的利用計算機把他們的工廠看成是機電一體化構想的試樣點。但是,經(jīng)過嚴密考察后,他們的結合是水平的──只在生產(chǎn)領域──包括主要的生產(chǎn)制造和管理階層。通用電器公司成為工廠汽車系統(tǒng)的主要賣主,已經(jīng)推出其宏偉計劃合并其旗下的數(shù)個公司,包括伊利機車廠、斯克奈塔氣輪機廠、夏洛茨維爾制造分工司。機電一體化的主要優(yōu)勢著重放在先進制造技術和工廠自動化。
機器設備的高利用率
典型的講,一套機電一體化機器設備的生產(chǎn)量是在獨立車間的環(huán)境下、相同的機器條件下的三倍。當機器一空閑下來時,就讓計算機調(diào)度每一個零件到這臺機器,同時在自動材料輸送關系系統(tǒng)中使零件運動,并且把適當?shù)挠嬎銠C程序下行傳輸?shù)竭@臺機器80,這樣就能使機電一體化系統(tǒng)達到很高的效率。另外,已經(jīng)固定在托板上的零件到達機器,以使零件裝卡時機器不必等待──把零件固定在托板上是單獨的工作站上完成的。
降低設備資金消耗
機器設備的高利用率,原因在于在作用同樣工作時機電一體化系統(tǒng)比傳統(tǒng)的機械系統(tǒng)需要更少的機器設備。當利用機電系統(tǒng)代替加工中心時,減少1/3的機器設備是正常的。
降低工人的勞動消耗
因為每一臺機器是完全在計算機控制下不用工人一直盯著工作,直接的減少了機器工人的監(jiān)工或者維修工、零件的檢察員,不太需要有技能的人員。例如在車間夾緊、卸下工件。然而,在機電一體化工作環(huán)境下與傳統(tǒng)的工作車間相比不需要更高的技術。勞動力資金的減少在某種程度上與傳統(tǒng)工作車間不需要的技術是相互抵消的。有計劃調(diào)度在制工件和減少產(chǎn)品設計到投產(chǎn)時間或從定貨到交貨時間。
與單獨車間環(huán)境下相比,利用機電一體化系統(tǒng)在減少在制工件方面是非常顯著的。據(jù)一些車間報道已經(jīng)減少了80%,這些都歸功于減少了定貨到交貨的時間的諸多因素,這些因素包括:全部生產(chǎn)零件所需的設備都集中在一個小的區(qū)域內(nèi);所需夾具的數(shù)量的減少;由于加工工藝被組合在工作單元中而引起的零件所必須通過的機器的數(shù)量的減少;以及分批進入的和已在機電一體化系統(tǒng)中的零件要進行有效的計算機調(diào)度。
對改變的產(chǎn)品的需求快速響應
機電一體化系統(tǒng)對于不同產(chǎn)品的生產(chǎn)需求和市場需求改變或者工程設計改變都有固有的靈活性。更進一步,備用件的需求不會大大擾亂正常的機電一體化系統(tǒng)的生產(chǎn)活動。
生產(chǎn)的可維護性
許多機電一體化系統(tǒng)能夠適度的降低當一個或更多的機器失效后不能正常工作的機率。當某臺機器失效后多余的機器和原材料控制系統(tǒng)使系統(tǒng)繞過失效的機器,因此,生產(chǎn)量始終保持在一個恒定的百分率上。
高的產(chǎn)品質(zhì)量
經(jīng)常性的監(jiān)督機電一體化系統(tǒng),特別是當與沒有與合作系統(tǒng)聯(lián)合的機器系統(tǒng)相比能夠更能提高產(chǎn)品的質(zhì)量,產(chǎn)品設計性能與生產(chǎn)能力的基本結合,高水平的自動化夾具數(shù)量和駐留的機器數(shù)量的減少,設計的更好的永久性夾具,更加注意零件與機器的調(diào)整,所有這些都使單個零件質(zhì)量良好,零件之間有極好的一致性,并且導致返工成本的大大減少。
靈活的控制
靈活的控制能夠顯著的增加產(chǎn)品的產(chǎn)量,在一些設施里,機電一體化系統(tǒng)可以在中班和晚班和無人看管條件下自動運行,這種幾乎無人的操作方式目前是例外的情況,而不是常規(guī),但是他可以變成常規(guī)。如果好的傳感器和計算機能夠控制和解決一些非預期的情況,例如刀具劃傷、零件流動阻滯等等。在這種操作模式下,監(jiān)察、安裝和維修可以在第一班即可完成。
靈活性
由于正確的操作可利用的占地面積的計劃,一個機電一體化系統(tǒng)最初可為低產(chǎn)量而設計。隨著需求的增長,可以容易的增添新機器,以提供需要的附加生產(chǎn)能力。
3: 機電一體化的組成
這一章節(jié)簡要的介紹機電一體化系統(tǒng)的原理,而且講述了需要機電一體化各個組成部分來實現(xiàn)機電一體化工藝技術。 機電一體化系統(tǒng)的 重點應放在 工廠自動化,因為工廠自動化作為機電一體化整體技術中辦公自動化和家庭自動化的基礎。
系統(tǒng)原理
機電一體化產(chǎn)品生產(chǎn)包括產(chǎn)品設計的所有方面,產(chǎn)品的生產(chǎn)制造和與工廠管理部門由數(shù)字化驅(qū)動的相互協(xié)調(diào)的計算機輔助系統(tǒng)。但不同于以往的其他工藝技術,他們還包括與確定工長江要制造的產(chǎn)品有關的工序,這里 恰好是日本人以勝人一籌之處,使得許多美國公司注意并想知道為什么它們(占有)的市場份額正在消失。
一份關于這種工藝的周密調(diào)查講揭示:日本人已創(chuàng)造了非常適合于用戶的新產(chǎn)品,以至我們的陳舊產(chǎn)品在市場上失去了光澤。他們引起了對他們產(chǎn)品的需要,并且是按照那個古老的原則做到這一點的,這個原則是:“給予顧客它所向要的東西,而不是給他認為他鄉(xiāng)要的東西。
與顧客分擔設計過程是一種有趣的過程,當把她作為機電一體化基本原理的一部分考慮時,這一過程為在工廠自動化方面發(fā)生的其他一切事實的動力。
,機電一體化功能一般分為三類:與用戶相關的產(chǎn)品設計的市場分析,在工廠現(xiàn)場的產(chǎn)品的生產(chǎn)制造,開明的工廠經(jīng)營管理。上述三大類功能,既強調(diào)需要改進的設計,產(chǎn)品的制造,開明的管理,不是必然相互排斥的。實際上,把機電一體化引入到這些系統(tǒng)的目的掃除它們之間的壁壘,從而使設計和制造系統(tǒng)能夠自然而然的連接起來,然而這三種功能構成討論是很有好處的,特別,當他們與典型的制造公司對應更能體現(xiàn)其好處。