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下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763計算機輔助設(shè)計的簡要歷史買文檔送全套圖紙 扣扣 414951605在我們講述 CAD 的基本理論之前,先說說他的簡史是比較合適的。CAD 是計算機時代的產(chǎn)品.它從早期的計算機繪圖系統(tǒng)發(fā)展到現(xiàn)在的交互式計算機圖形學(xué).兩個這樣的系統(tǒng)包括:麻省理工學(xué)院的 Sage Project 及Sketchpad。Sage Project 旨在開發(fā) CRT 顯示器及操作系統(tǒng). Sketchpad 是在 Sage Project 下發(fā)展起來的 .CRT 顯示和光筆輸入用于與系統(tǒng)進行交互操作.CAD 與初次出現(xiàn)的 NC 和 APT(自動編程工具)碰巧同時出世.后來,X-Y 繪圖儀作為計算機繪圖的標(biāo)準(zhǔn)硬拷貝輸出裝置使用,一個有趣的現(xiàn)象是 X-Y 繪圖儀與 NC 鉆床具有相同的基本機構(gòu),除了繪圖筆 NC 機床上的主軸刀具替代之外。開始,CAD 系統(tǒng)僅僅是一個帶有內(nèi)置設(shè)計符號的繪圖編輯器,供用戶使用的幾何元素只有直線、圓弧、以及兩者的組合。自由曲線及其曲面的發(fā)展,如昆氏嵌面、貝塞爾嵌面以及 B-樣條曲線,使 CAD 系統(tǒng)可用于復(fù)雜曲線與曲面設(shè)計。三維 CAD 系統(tǒng)允許設(shè)計者步入三維設(shè)計空間。由于一個三維設(shè)計模型包含了 NC 刀具路徑編程所需的足夠信息,所以能夠開發(fā) CAD 與 NC 之間聯(lián)系的系統(tǒng)。所謂交鑰匙的 CAD/CAM 系統(tǒng)便是根據(jù)這一概念開發(fā)的,并從 20世紀(jì) 70 年代至 80 年代流行起來。20 世紀(jì) 70 年代,三維實體建模的發(fā)明標(biāo)志著 CAD 一個新時代的開始。過去的三維線框模型僅用其邊界來表達一個物體。這在某種意義上是模糊的,一個簡單的模型可能有幾種解釋。同時也無法獲得一個模型的體積信息。實體模型包含完整的信息,因此,它們不僅可用于生成工程圖,而且也可在同一模型上完成工程分析。后來,開發(fā)了許多商業(yè)系統(tǒng)和研究系統(tǒng)。這些系統(tǒng)中相當(dāng)多的是基于 PADL 和 BUILD 系統(tǒng)。盡管它們在表達上是強有力的,但仍然存在許多缺陷。例如,這種系統(tǒng)要有極強的計算能力和內(nèi)存需求,非常規(guī)的物體建模方式以及標(biāo)注公差能力的缺乏,這一切已阻礙了 CAD 應(yīng)用。直到 20 世紀(jì)80 年代中期,實體建模開始介入設(shè)計環(huán)境。今天實體建模的應(yīng)用如同繪圖和線框模型應(yīng)用一樣普遍。在個人計算機上,CAD 已走向大眾化。這種發(fā)展使 CAD 應(yīng)用面廣并且很經(jīng)濟。CAD 原本作為一種工具僅被航空和其它主要工業(yè)企業(yè)使用。諸如AutoCAD、VersaCAD、CADKEY 等個人機 CAD 軟件包的引入,使小型公司乃下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763至個人可以擁有并使用 CAD 系統(tǒng)。到 1988 年為止已銷售 10 萬個以上的 PC CAD 軟件包。今天,基于個人計算機的實體建摸的 PC CAD 易于獲得,并且銷售變得更為普及。由于微型計算機的迅速發(fā)展使得個人計算機能夠承受實體模型需要的大量計算負荷,所以如今許多實體模型在 PC 機上運行,并且作為平臺 已不成為一個問題。隨著標(biāo)準(zhǔn)圖形用戶界面的發(fā)展,CAD 系統(tǒng)可以很容易地從一臺計算機傳送,大多數(shù) CAD 系統(tǒng)都能在不同平臺上運行。在大型計算機、工作臺和基于個人計算機的 CAD 系統(tǒng)之間幾乎沒有區(qū)別。計算機輔助設(shè)計的結(jié)構(gòu)一個 CAD 系統(tǒng)包含三個主要部分:(1)硬件 計算機及輸入/輸出裝置。(2)操作系統(tǒng)軟件。(3)應(yīng)用軟件 CAD 軟件包。硬件主要用于支持軟件功能。在 CAD 系統(tǒng)中使用著種類繁多的硬件。操作系統(tǒng)軟件是 CAD 應(yīng)用軟件與硬件之間的界面。操作系統(tǒng)軟件管理著硬件運行并提供許多諸如創(chuàng)建 和取消操作任務(wù)、控制任務(wù)的進程、在任務(wù)間分配硬件資源、提供通向軟件資源,如文件、編輯器、編譯和應(yīng)用程序的通道等基本功能。這不僅對 CAD 軟件很重要,而且對非 CAD 軟件也很重要。應(yīng)用軟件是 CAD 系統(tǒng)的核心。它由二維和三維建摸、繪圖、工程分析等程序組成。一個 CAD 系統(tǒng)的功能便建立在應(yīng)用軟件中。正是應(yīng)用軟件使一種CAD 軟件包區(qū)別于另一種,通常應(yīng)用軟件是依賴于操作系統(tǒng)的。要把在一個操作系統(tǒng)上運行的 CAD 系統(tǒng)移到另一個操作系統(tǒng)上,并不像編譯軟件那樣微不足道。因此也必須注意操作系統(tǒng)。計算機輔助設(shè)計計算機輔助設(shè)計給了設(shè)計者去嘗試幾個可行的解決方案的能力。通常還需要某些形式的設(shè)計分析計算,而為了這一任務(wù)已經(jīng)編寫了許多程序。計算機為設(shè)計者對所建議的各種結(jié)構(gòu)設(shè)計的分析和為最終設(shè)計準(zhǔn)備正式繪圖提供了強有力的工具。在二維繪圖領(lǐng)域中,計算機方法能夠提供比傳統(tǒng)的紙和筆的方法更有意義、更大成本節(jié)約的優(yōu)點,但是一個 CAD 系統(tǒng)并不僅是一個電子繪圖板。計算機繪圖系統(tǒng)可使設(shè)計者設(shè)計出既快又準(zhǔn)確的圖形,并且很容易修改。在涉及到重復(fù)性工作時,會戲劇性產(chǎn)生復(fù)制產(chǎn)品,因為標(biāo)準(zhǔn)圖形只要一次構(gòu)建成功,就可下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763以從圖庫中取出。剪切和粘貼技術(shù)作為節(jié)約勞動力的輔助工具被使用。當(dāng)幾個分項目設(shè)計人員從事同一個工程時,要建立中心數(shù)據(jù)庫,使得由某一個人繪的細節(jié)圖可以很容易地合并到其它不同的裝配圖中。中心數(shù)據(jù)庫也可作為標(biāo)準(zhǔn)參考零件庫使用。有限元是一項成熟的應(yīng)力分析技術(shù),它多被土木工程和機械工程所采用。它由將結(jié)構(gòu)劃分成有限個的小單元所組成,并計算每一個單元之間的作用力。如果被分割的單元足夠小,就能對一個結(jié)構(gòu)或?qū)嶓w的內(nèi)部應(yīng)力獲得一個好的估計。這些計算機設(shè)計慣用于大型結(jié)構(gòu)物的設(shè)計,諸如船體、橋梁、飛機機身和海面油井平臺。汽車工業(yè)也使用類似的方法來設(shè)計和制造車身。二維繪圖CAD 使多視圖的二維繪圖成為可能,視圖空間可以從微米到米的比例范圍內(nèi)無限變化。它提供給機械設(shè)計師放大的功能,即使在恰當(dāng)配合的裝配零件中最小的零件也能看清楚,設(shè)計程序甚至能自動辨認 CAD 裝配圖中的潛在問題。針對具有不同特征的零件,如運動的或靜止的,在顯示時可以被指定成不同的顏色。為了有利于工程設(shè)計的變化,可使用帶有自動尺寸變化的系統(tǒng)對零件進行尺寸標(biāo)注。三維繪圖隨著三維建模的出現(xiàn),設(shè)計者具有了更多的自由度。他們可以生成三維零件圖并且可以無限制地修改以獲得所需的結(jié)果。通過有限元分析,應(yīng)力加到計算機模型上,并且以圖形化的方式顯示其結(jié)果,在產(chǎn)品物理模型真正產(chǎn)生之前,對設(shè)計中的任何內(nèi)在問題給設(shè)計者一個快速的反饋。三維模型可用線框、曲線或?qū)嶓w方式生成。在線框模型中,直線和圓弧構(gòu)成了模型邊界。結(jié)果是一個可以從任何位置觀察的三維模型,但仍只是一個框架形式。創(chuàng)建曲面猶如在骨架上包上皮。一旦這樣生成后,模型就可以被渲染,使得圖形看上去更逼真。曲面模型普遍用于構(gòu)建板金的展開和重疊以用于制造。實體模型是最復(fù)雜的建模層次,并且用于建立實體模型的程序在一段時期內(nèi)只用在大型計算機上。只有近年來微型計算機才達到這個能力水平,也可以運行復(fù)雜的算法,生成實體模型。計算機“認為”實體模型是一種具有實體質(zhì)量的模型,所以它可被“鉆孔” “加工” “焊接” ,好象它是一個實際的零件。它能夠由任何材料構(gòu)成并呈現(xiàn)其材料特性,因此,能夠進行質(zhì)量計算。下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763計算機輔助繪圖的好處用計算機完成繪圖及設(shè)計任務(wù)的好處是令人難忘的:提高速度、提高準(zhǔn)確性、減少硬拷貝存儲空間及易于恢復(fù)信息、加強信息傳輸能力、改善傳輸質(zhì)量和便于修改。速度工業(yè)用計算機能以平均每秒 3300 萬次完成一項任務(wù);更新的計算機其速度更快。用計算機計算零件的變形量是一個重要功績。當(dāng)理論上的載荷力加到零件上時、通過計算機進行有限元分析或者在監(jiān)視器上顯示一個城市的整體規(guī)劃時,這兩者都是既費時又計算量大的任務(wù)。AutoCAD 軟件可根據(jù)需要多次復(fù)制所需模型的形狀和幾何尺寸,快速自動地進行剖面填充及尺寸標(biāo)注。準(zhǔn)確AutoCAD 程序依靠操作系統(tǒng)及計算機平臺每點具有 14 位的精度。這在用數(shù)學(xué)計算諸如一個圓的線段數(shù)、程序必須圓整線段時是十分重要的。存儲計算機能夠在物理空間中存儲上千幅圖,這空間能夠存儲上百幅手工圖。而且計算機能夠很容易地搜索和找到一幅圖,只要操作者擁有正確的文件名。傳輸由于計算機的數(shù)據(jù)是以電子形式存儲,它能被送到各種位置。最明顯的位置是監(jiān)視器。計算機可以在屏幕上以不同的方式顯示數(shù)據(jù),如圖形,并能方便地將數(shù)據(jù)轉(zhuǎn)換成可讀圖形。這些數(shù)據(jù)也可被傳送給繪圖機,打印出常見的圖紙,通過直接連接到計算機輔助制造機床或由電話線傳到地球的任何地方。你可以不再冒損失或丟失的危險去郵寄圖紙,現(xiàn)在圖紙可以通過電信網(wǎng)立即發(fā)送到目的地。下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763A Brief History of?。茫粒腂efore we present the basics of CAD ,it is appropriate to give a brief history . CAD is a product of the computer era. It originated from early computer graphic systems to the development of interactive computer graphics. Two such systems include the Sage Project at the Massachusetts Institute of Technology (MIT) and Sketchpad. The Sage Project was aimed at developing CRT displays and operating systems. Sketchpad was developed under the Sage Project. A CRT display and light pen input were used to interact with the system. This coincidentally happened at about the same time that NC and APT(Automatically Programmed Tool)first appeared. Later, X-Y plotters were used as the standard hard-copy output device for computer graphics. An interesting note is that an X-Y plotter has the same basic structure as a NC drilling machine except that a pen is substituted for the tool on NC spindle.In the beginning, CAD systems were no more than graphics editor with some built-in design symbols. The geometry available to the user was limited to lines, circular arcs, and the combination of the two. The development of free-form curves and surfaces, such as Coon’s patch, Bezier’s patch, and B-spline, enable a CAD system allow to be used for sophisticated curves and surface design. Three-dimensional CAD system allow a designer to move into the third dimension. Because a three-dimensional model contains enough information for NC cutter-path programming, the linkage between CAD and NC can be developed. So called turnkey CAD/CAM systems were developed based on this concept and became popular in the 1970s and 1980s.The 1970s marked the beginning of a new era in CAD-the invention of three-dimensional solid modeling. In the past, three-dimensional, wire-frame models represented an object only by its bounding edges. They are ambiguous in the sense that several interpretations might be possible for a single model. There is also no way to find the volumetric information of a model. Solid models contain complete 下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763information; therefore, not only can they be used to produce engineering drawing, but engineering analysis can be performed on the same model as well. Later many commercial systems and research systems were developed. Quite a few of these systems were based on the PADL and BUILD systems. Although they are powerful in representation, many deficiencies still exist. For example, such systems have extreme computation and resource (memory) requirements, an unconventional way of modeling object and a lack of tolerance capability have all hindered CAD applications. It was not until the mid-1980s that solid modelers made their way into the design environment. Today, their use is as common as drafting and wire-frame model applications.CAD implementations on personal computers (PCs) have brought CAD to the masses. This development has made CAD available and affordable. CAD originally was a tool used only by aerospace and other major industrial corporation. The introduction of PC CAD packages, such as, AutoCAD, VersaCAD, CADKEY, and so on, has made it possible for small companies and even individuals to own and use CAD systems. By1980, more than 100,000 PC CAD packages had been sold. Today PC-based solid modelers are available and are becoming increasingly popular. Because rapid developments in microcomputers have enabled PCs to carry the heavy computational load necessary for solid modeling, many solid modelers now run on PCs, and the platform has become less of an issue. With the standard graphics user interface (GUI), CAD systems can be ported easily from one computer to another , Most major CAD systems are able to run on a variety of platforms. There is little difference between mainframe, workstation, and PC-based CAD systems.The Architecture of CADA CAD system consists of three major parts:(1)Hardware computer and input/output(I/O)devices.(2)Operating system software.(3)Application software CAD package.Hardware is used to support the software functions. A wide range of hardware is used in CAD systems. The operating system software is the interface between the CAD application software and the hardware. It supervises the operation of the 下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763hardware and provides basics functions such as creating and removing operation tasks, and providing access to software resources such as files, editors, compilers and utility programs. It is important not only for CAD software, but also for non-CAD software.The application software is the heart of a CAD system. It contains of programs that do 2-D and 3-D modeling, drafting, and engineering analysis. The functionality of a CAD system is built into the application software. It is application software that makes one CAD package different form another. Application software is usually operating-system-dependent. To transport a CAD system running in one operating system to another operating system is not as trivial as recompiling the software. Therefore, attention must be given to the operating system as well.Computer Aided DesignComputer aided design gives the designer the ability to experiment with several possible solutions. Usually some forms of design analysis calculations need to be done and many programs have been written for this task. The computer provides the designer with a powerful tool for analyzing proposed designs and for preparing formal drawing of the final design.Two-dimensional drawing is one area in which computer methods can off significant, quantifiable cost advantages over traditional paper and pen methods, but a CAD system is not just an electronic drawing board. Computer drawing systems enable designers to produce fast accurate drawings and easily modify them. Draught productivity rises dramatically when repetitive work is involved, since standard shapes are constructed only once and can be retrieved from a library. Cut and paste techniques are used as labor-saving aids. When several detail drawn by one person can be easily incorporated into different assemble drawing. This central database also serves as a library of standard preferred computers.Finite element is a sophisticated stress analysis technique much used by civil and mechanical engineers. It consists of dividing a structure into small, but finite, components and calculating the force between each element. If the elements are small enough, a good estimate of the internal stresses in a structure or solid body can be obtained. These computer techniques are routinely used in the design of large structure such as ship hulls, bridges, aircraft fuselages and offshore oil rig. The motor 下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763car industry also uses similar methods for design and manufacture of car bodies.Two-dimensional DrawingsCAD makes possible multiview 2D drawing, with an endless possibility of views in range of scales from microns to meters to meters. It gives the mechanical designer the ability to magnify even the smallest of components to ascertain if the assembled components fit properly and even to design programs to identify automatically potential problems in CAD assembly. Parts with different characteristics, such as movable or stationary, can be assigned different colors on the display. Parts can be dimensioned with automatic dimensioning changes, allowing for expedient engineering design changes.Three-Dimensional DrawingsDesigners have even more freedom with the advent of 3D modeling. They can 3D parts and manipulate them in endless variations to achieve the desired results. Through finite element analysis FEA), stress can be applied to a computer model and the results graphically displayed, giving the designer guick feedback on any inherent problems in a design before the creation of a physical prototype.3Dmodels can be created in wire-frame, in surfaces or in solid form. In wire-frame, lines and arcs form edges that generate the model. The result is a 3D form that can be viewed from any location but still only a skeletal form. Creating a surface stretches a skin over the skeleton (Fig.8-1b).Once this is done, the model can be rendered so that it appears more tangible. Surface models are commonly used in the creation of sheet metal developments that can be unfolded for manufacture.Solid models are the most complex level of modeling and while the programs to create them have been available for some time on large mainframe computers, it is only recently that microcomputers have reached a level of power that allows the running of the sophisticated algorithms needed to create solid model(Fig.8-2). The computer “thinks” the solid is sold mass so it can be “drilled”, “machined,”or “welded” as if it were an actual physical part. It can be made out of any material’s characteristics, thereby allowing calculations of mass to be made.CAD’S BenefitsThe benefits of computer use in drafting and design tasks are impressive: 下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763increased speed, greater accuracy, reduction of hardcopy storage space as well as better recall, enhanced communication capabilities, improve quality and easier modification.Speed A person computer used in industry can perform a task at an average rate of 33 million operations per second; newer computer are even faster. This is an important feat when using it to calculate the amount of deflection of a component, when theoretical physical forces are applied to it, through finite element analysis(FEA) or when displaying an entire city plan on a monitor, both of which are time-consuming and calculation-intensive tasks. AutoCAD software can duplicate any geometry as many times as required and can also perform crosshatching and dimensioning automatically and equally as fast.AccuracyThe AutoCAD program has an accuracy of 14 significant digits of precision for each point, depending on the operating system and computer platform. This extremely important when the program must round off numbers during mathematical calculations such as segmenting a circle.StorageThe computer can store thousands of drawings in the physical space that it would take to store hundreds of manual drawings. Also, the computer can search and find a drawing with ease, as long as the operator possesses the correct.Communication Because the computer’s data is stored in an electronic form, it cam be sent to s variety of locations. The first obvious location is the monitor. The computer can display the data on the screen in different forms such as graphics, easily converting the data into readable drawing. The data can also be a plotter to produce the familiar paper drawing, via a direct link to a computer-aided manufacturing (CAD) machine or via telephone to anywhere around the globe. You no longer have to mail drawing, risking damage and loss; they can not be at their destination instantly via the telecommunications network.下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763課題研究擬采用的手段和工作路線]課程設(shè)計方法:1) 獨立思考,繼承和創(chuàng)新設(shè)計時,要認真閱讀參考資料,繼承或借鑒前人的設(shè)計經(jīng)驗和成果,但不地進行改進和創(chuàng)新。能盲目地全盤抄襲,應(yīng)根據(jù)具體的設(shè)計條件和要求,大膽2) 全面考慮 機械零部件地強度、剛度、工藝性、經(jīng)濟性和維護等要求任何零部件的機構(gòu)和尺寸,除去考慮它的強度剛度外,還應(yīng)該綜合考慮零件本身及整個部件的工藝性要求、經(jīng)濟性要求等才能確定。3) 設(shè)計方法通過計算確定零件的基本尺寸,再通過草圖設(shè)計決定其具體結(jié)構(gòu)和尺寸;而有些零件則需先經(jīng)初算和繪草圖,得出初步符合設(shè)計條件的基本結(jié)構(gòu)尺寸,然后再進行必要得計算,根據(jù)計算的結(jié)果,再對結(jié)構(gòu)和尺寸進行修改。4) 使用標(biāo)準(zhǔn)和規(guī)范設(shè)計時應(yīng)盡量使用標(biāo)準(zhǔn)和規(guī)范,這有利于零件的互換性和工藝性,同時也可減少設(shè)計工作量、節(jié)省設(shè)計時間,對于國家標(biāo)準(zhǔn)或部門規(guī)范,一般都要嚴(yán)格遵守和執(zhí)行。設(shè)計中采用標(biāo)準(zhǔn)或規(guī)范的多少,時評價設(shè)計質(zhì)量的一項指標(biāo)。因此,課程設(shè)計中,凡是有標(biāo)準(zhǔn)或規(guī)范的,應(yīng)該盡量采用工作路線:1) 設(shè)計準(zhǔn)備了解設(shè)計任務(wù)書,明確設(shè)計要求、工作條件、設(shè)計內(nèi)容的步驟;通過查閱有關(guān)設(shè)計資料,觀看電教片和參觀實物或模型等,了解設(shè)計對象的性能、結(jié)構(gòu)及工藝性;準(zhǔn)備好設(shè)計需要資料、繪圖工具;擬定設(shè)計計劃等。2) 校核 V 帶及減小噪音的措施擬定和確定工作方案;選擇電機;校核 V 帶。大致分析壓縮機產(chǎn)生噪聲的原因和有效減小噪聲的措施。3) 工作原理草圖設(shè)計繪制工作原理草圖;進行各零部件和結(jié)構(gòu)件設(shè)計。4) 繪制零件工作圖繪出零件的必要視圖;標(biāo)注尺寸、公差及表面粗糙度;編寫技術(shù)要求和標(biāo)題欄等5) 編寫設(shè)計說明書寫明整個設(shè)計的主要計算和一些技術(shù)說明。下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763第一章. 引 言目前,容積式壓縮機的全球年產(chǎn)量為 1.5 億余臺,其中大多數(shù)被應(yīng)用于空氣動力和制冷系統(tǒng)。過去的 30 年間,轉(zhuǎn)子型線的改進使螺桿壓縮機內(nèi)部泄漏徹底減少,同時技術(shù)日益成熟的機床可以將形狀較為復(fù)雜零件的加工公差控制在工程允許的 3μm 以內(nèi),以致傳統(tǒng)的往復(fù)式壓縮機在許多應(yīng)用領(lǐng)域逐步被螺桿壓縮機所替代。人工分析計算的方法是設(shè)計者預(yù)測壓縮機性能的主要手段,并且在此過程中取得了一些技術(shù)上的突破,但其適用范圍和準(zhǔn)確度與現(xiàn)代數(shù)控機床和裝配過程相比卻遜色很多。因此,先進的分析手段增大了技術(shù)創(chuàng)新的可能性,進而提高螺桿壓縮機的性能,降低制造成本,進一步擴大螺桿壓縮機的應(yīng)用范圍。轉(zhuǎn)子型線的改進依然是提高螺桿壓縮機性能最有效的手段,依靠經(jīng)驗確定轉(zhuǎn)子齒型和轉(zhuǎn)子大量采用通用型線的歷史將被逐步完善的先進、合理、高效的轉(zhuǎn)子加工工序所改寫,從而取得良好的應(yīng)用成效。另外,改善的壓縮機內(nèi)部流動模型有助于更好地進行孔口設(shè)計,軸承負荷及其脈動的準(zhǔn)確判定有助于選擇更為合適的軸承。最后,如果可以較為準(zhǔn)確地估計由于壓縮機內(nèi)部溫度及壓力變化引起的轉(zhuǎn)子和機殼的扭轉(zhuǎn)變形,我們就可以在機器的加工過程中采取相應(yīng)的措施以便將溫度及壓力脈動的不良影響降至最小。本文涵蓋了可能引發(fā)螺桿壓縮機技術(shù)創(chuàng)新的最新流動模型與分析方法,以及利用這些手段提高機器性能、擴展應(yīng)用范圍的典型案例。下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763第二章 螺桿壓縮機的介紹一. 發(fā)展歷程20 世紀(jì) 30 年代,瑞典工程師 Alf Lysholm 在對燃氣輪機進行研究時,希望找到一種作回轉(zhuǎn)運動的壓縮機,要求其轉(zhuǎn)速比活塞壓縮機高得多,以便可由燃氣輪機直接驅(qū)動,并且不會發(fā)生喘振。為了達到上述目標(biāo),他發(fā)明了螺桿壓縮機。在理論上,螺桿壓縮機具有他所需要的特點,但由于必須具有非常大的排氣量,才能滿足燃氣輪機工作的要求,螺桿壓縮機并沒有在此領(lǐng)域獲得應(yīng)用。盡管如此,Alf Lysholm 及其所在的瑞典 SRM 公司,對螺桿壓縮機在其它領(lǐng)域的應(yīng)用,繼續(xù)進行了深入的研究。1937 年,Alf Lysholm 在 SRM 公司研制成功了兩類螺桿壓縮機試驗樣機,并取得了令人滿意的測試結(jié)果。1946 年,位于蘇格蘭的英國 James Howden 公司,第一個從瑞典 SRM 公司獲得了生產(chǎn)螺桿壓縮機的許可證。隨后,歐洲、美國和日本的多家公司也陸續(xù)從瑞典 SRM 公司獲得了這種許可證,從事螺桿壓縮機的生產(chǎn)和銷售。最先發(fā)展起來的螺桿壓縮機是無油螺桿壓縮機。1957 年噴油螺桿空氣壓縮機投入了市場應(yīng)用。1961 年又研制成功了噴油螺桿制冷壓縮機和螺桿工藝壓縮機。過隨后持續(xù)的基礎(chǔ)理論研究和產(chǎn)品開發(fā)試驗,通過對轉(zhuǎn)子型線的不斷改進和專用轉(zhuǎn)子加工設(shè)備的開發(fā)成功,螺桿壓縮機的優(yōu)越性能得到了不斷的發(fā)揮。二. 發(fā)展方向螺桿壓縮機廣泛應(yīng)用于礦山、化工、動力、冶金、建筑、機械、制冷等工業(yè)部門,在寬廣的容量和式?jīng)r范圍內(nèi),逐步替代了其它種類的壓縮機,統(tǒng)計數(shù)據(jù)表明,螺桿壓縮機的銷售量已占其它容積式壓縮機銷售量的 80%以上,在所有正在運行的容積式壓縮機中,有 50%的是螺桿壓縮機。今后螺桿壓縮機的市場份額仍將不斷的擴大。為了進一步改善螺桿壓縮機的性能,擴大其應(yīng)用范圍,應(yīng)在以下幾個方面作深入研究。下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 13041397631、 在型線嚙合特性、轉(zhuǎn)子受力變形和受熱膨脹等方面研究的基礎(chǔ)上,創(chuàng)造新的高效型線,以進一步提高螺桿壓縮機的效率。2、 分析噴油對、螺桿壓縮機工作過程中泄漏、換熱和摩擦等方面的影響機理,使噴油參數(shù)的設(shè)計從目前的經(jīng)驗設(shè)計提高到機理設(shè)計和優(yōu)化設(shè)計。3、 研究吸氣和排氣過程的流動特性,在流場分析的基礎(chǔ)上,進一步合理配置吸排氣孔口和相關(guān)連接管道。4、 分析螺壓縮機的噪音產(chǎn)生機理,研究型線設(shè)計和孔口配置等因素對噪聲指標(biāo)的影響,從而更有效的降低噪聲。5、 研究轉(zhuǎn)子螺旋齒面的加工工藝,除研究高精度和同生產(chǎn)率的專用設(shè)備外,還要研究新型少切削和無切削工藝。6、 擴大螺桿壓縮機的參數(shù)范圍,主要應(yīng)向小容積流量、高排氣壓力方向發(fā)展。同時,研究氣量調(diào)節(jié)機構(gòu)與智能控制系統(tǒng),提高調(diào)節(jié)式?jīng)r下壓縮機運轉(zhuǎn)的經(jīng)濟性,進一步擴大螺桿壓縮機的應(yīng)用范圍。三. 螺桿壓縮機的研究意義壓縮機可分二大類,容積式壓縮機和動力式壓縮機。容積式壓縮機又可分往復(fù)式和回轉(zhuǎn)式。本可題研究的是螺桿空氣壓縮機,屬于雙軸壓縮機。螺桿壓縮機-- 是回轉(zhuǎn)容積式壓縮機,在其中兩個帶有螺旋型齒輪的轉(zhuǎn)子相互嚙合,從而將氣體壓縮并排出。用可靠性高的螺桿式壓縮機取代易損件多,可靠性差的活塞式壓縮機,已經(jīng)成為必然趨勢。日本螺桿壓縮機 1976 年僅占 27%,1985 年則上升到 85%。目前西方發(fā)達國家螺桿壓縮機市場占有率為 80%,并保持上升勢頭。螺桿壓縮機具有結(jié)構(gòu)簡單、體積小、沒有易損件、工作可靠、壽命長、維修簡單等優(yōu)點。螺桿壓縮機有雙螺桿與單螺桿兩種。單螺桿壓縮機的發(fā)明比雙螺桿壓縮機晚十幾年,設(shè)計上更趨合理、先進。單螺桿壓縮機克服了雙螺桿壓縮機不平衡、軸承易損的缺點;具有壽命長,噪音低,更加節(jié)能等優(yōu)點。相對其他復(fù)雜回轉(zhuǎn)機械來說,螺桿壓縮機的設(shè)計制造還是比較簡單的。由于螺桿壓縮機的回轉(zhuǎn)運動部件只有兩個轉(zhuǎn)子,所以它可以可靠地高速運轉(zhuǎn)。高精度的轉(zhuǎn)子齒型銑削與磨削加工可以較低的成本將齒間間隙控制在 30~503μm下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763之間。與早期的機器相比,內(nèi)部泄漏已經(jīng)大幅減少??梢?,螺桿壓縮機已經(jīng)成為精密、高效的 機械,并且能夠適用于較大的壓力與排量范圍。因此,容積式壓縮機的大部分市場與應(yīng)用場合已被螺桿壓縮機占據(jù)。螺桿壓縮機的發(fā)展趨勢是在滿足性能要求的前提下,減小機器的尺寸。這就意味著需要在保持較高效率的同時盡可能提高轉(zhuǎn)子齒頂速度。在一般的實驗中,廣泛采用的軸承是滾動軸承,因為與滑動軸承相比,滾動軸承允許更小的間隙。另外,為使吸氣與排氣孔口處的氣流速度降到最低,吸排氣孔口需要開設(shè)得盡可能大。上述這些設(shè)計原則在任何應(yīng)用場合中都是普遍適用的。與先進的轉(zhuǎn)子型線一樣,為了取得螺桿壓縮機設(shè)計的最大進步,能夠?qū)p失降到最低的其他組件的改進也是非常重要的。所以,對轉(zhuǎn)子與機殼之間的間隙進行合理選擇也是很有必要的,尤其是在高壓端。當(dāng)間隙較小時,需要采用較昂貴的優(yōu)質(zhì)軸承,當(dāng)通過預(yù)緊將間隙控制在允許范圍內(nèi)時,可以采用比較廉價的軸承。 螺桿壓縮機尤其是噴油螺桿壓縮機通常在較高壓力差下工作,單級壓比較高,產(chǎn)生的軸向力與徑向力較大。中小型 壓縮機一般采用滾動軸承。由于轉(zhuǎn)子中心距受其一定的影響,為設(shè)計出滿意的產(chǎn)品,滾動軸承的選用及校核也應(yīng)慎重。值得一提的是,近期研發(fā)出的一種摩擦很小的滾動軸承提供了一個不錯的選擇,詳細參見 Meyers[37]。通常在轉(zhuǎn)子的高壓端設(shè)有兩個軸承來分別承受軸向力與徑向力。轉(zhuǎn)子間的接觸力大小取決于它們之間傳遞的扭矩,當(dāng)陰陽轉(zhuǎn)子直接接觸時,接觸力較大。當(dāng)壓縮機的驅(qū)動力矩由陽轉(zhuǎn)子傳送時,接觸力相對較小。倘若將驅(qū)動力矩由陰轉(zhuǎn)子傳送,產(chǎn)生的接觸力非常大,這是不允許的。噴入壓縮機內(nèi)的潤滑油也有潤滑軸承的作用,但是為了盡量減小摩擦損失,軸承的供油與回油系統(tǒng)是獨立的。機體上的噴油孔口開設(shè)在由熱力計算結(jié)果得出的氣體溫度與潤滑油溫度相等的位置,除此之外,噴油孔口應(yīng)位于轉(zhuǎn)子螺旋線上方,這樣,潤滑油可以從陰轉(zhuǎn)子齒頂沿螺旋齒面切線方向進入機體,達到回收所噴入潤滑油的動能的目的。為將吸排氣孔口的流動損失降到最低,螺桿壓縮機還應(yīng)符合以下技術(shù)指標(biāo)。進入壓縮機的氣體的流道應(yīng)盡量避免彎曲,這就要求吸氣孔口要開設(shè)在機殼上,另外,盡量擴大進氣的流通面積從而降低吸氣孔口處的氣體流速。排下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763氣孔口的尺寸主要是由熱力性能所要求的內(nèi)壓力比決定的,還應(yīng)考慮降低排氣流速和降低內(nèi)部、排氣孔口處流動損失的需要。機殼的設(shè)計加工要盡量減小其重量,還應(yīng)配置加強筋以提高高壓下的強度。雖然螺桿壓縮機現(xiàn)在已經(jīng)是一種發(fā)展比較成熟的產(chǎn)品,但由于以計算機建模與數(shù)值分析為主的工程科學(xué)的介入,我們還可以在設(shè)計過程中做出更大的改進,提高效率、減小機器尺寸、降低制造成本等。另外,為了達到最優(yōu)化的設(shè)計,軸承技術(shù)與潤滑的改善也是十分重要的.下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或1304139763下載論文就送你全套 CAD 圖紙,Q 咨詢 414951605 或 1304139763四.螺桿式空壓機原理1.吸氣過程: 螺桿式的進氣側(cè)吸氣口,必須設(shè)計得使壓縮室可以充分吸氣,而螺桿式壓縮機并無進氣與排氣閥組,進氣只靠一調(diào)節(jié)閥的開啟、關(guān)閉調(diào)節(jié),當(dāng)轉(zhuǎn)子轉(zhuǎn)動時,主副轉(zhuǎn)子的齒溝空間在轉(zhuǎn)至進氣端壁開口時,其空間最大,此時轉(zhuǎn)子的齒溝空間與進氣口之自由空氣相通,因在排氣時齒溝之空氣被全數(shù)排出,排氣結(jié)束時,齒溝乃處于真空狀態(tài),當(dāng)轉(zhuǎn)到進氣口時,外界空氣即被吸入,沿軸向流入主副轉(zhuǎn)子的齒溝內(nèi)。當(dāng)空氣充滿整個齒溝時,轉(zhuǎn)子之進氣側(cè)端面轉(zhuǎn)離了機殼之進氣口,在齒溝間的空氣即被封閉。 2、封閉及輸送過程: 主副兩轉(zhuǎn)子在吸氣結(jié)束時,其主副轉(zhuǎn)子齒峰會與機殼閉封,此時空氣在齒溝內(nèi)閉封不再外流,即[封閉過程]。兩轉(zhuǎn)子繼續(xù)轉(zhuǎn)動,其齒峰與- 1.請仔細閱讀文檔,確保文檔完整性,對于不預(yù)覽、不比對內(nèi)容而直接下載帶來的問題本站不予受理。
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