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畢業(yè)設(shè)計(論文)任務(wù)書
機制 專業(yè) 2002 年級
2006 年3 月28 日批準(zhǔn)
專業(yè)負(fù)責(zé)人: 喬 水 明
發(fā)給學(xué)生: 王中蔚 賀 兵
1.畢業(yè)設(shè)計(論文)題目:CA6140機床后托架加工工藝及夾具設(shè)計
2.學(xué)生完成全部任務(wù)期限: 2006 年 6 月 9 日
3.任務(wù)要求：（1）、設(shè)計內(nèi)容：制訂年產(chǎn)5000臺CA6140機床后托架的加工工藝；
（2）、設(shè)計主視圖中的三孔的加工夾具；
（3）、設(shè)計銑底面的夾具；
（4）、設(shè)計俯視圖中4孔的加工夾具；
（5）、提交夾具裝配圖、零件圖、加工工藝卡片、設(shè)計說明書及精度分析等相關(guān)設(shè)計分析結(jié)果。
注意：多人做一題時，設(shè)計方案、內(nèi)容不能相同
4.實驗(調(diào)驗)部分內(nèi)容要求:
（1）、查閱相關(guān)資料，分析所給題目的零件結(jié)構(gòu)工藝性，編排出該零件的合理的加工工藝過程，選擇各加工工序的合理的切削用量，計算各工序的定額，填寫零件的加工工藝卡片；
（2）、完成給定加工面的夾具設(shè)計（須有方案分析比較、優(yōu)選），每套夾具須完成裝配圖1張，夾具主要零、部件2-3張；
（3）、編寫夾具的設(shè)計說明書，字?jǐn)?shù)在15000字以上。
5.文獻(xiàn)查閱及翻譯要求:
（1）、機械加工工藝人員手冊；
（2）、機床家具設(shè)計手冊；
（3）、機床夾具圖冊；
（4）、翻譯有關(guān)機械制造方面10000個字符以上的外文資料，字?jǐn)?shù)不得少于三千。
6.發(fā)出日期: 2006 年 2 月 18 日
指導(dǎo)教師: 盧 宗 彪 (簽名)
完成任務(wù)日期: 2006 年 6 月 9 日
學(xué)生:賀 兵(簽名)
攀枝花學(xué)院本科畢業(yè)設(shè)計（論文） 外語文翻譯
攀枝花學(xué)院本科畢業(yè)設(shè)計（論文）
外文譯文
院 （系）： 機電工程學(xué)院
專 業(yè)： 機械設(shè)計制造及其自動化
姓 名： 賀 兵
學(xué) 號： ZJD02078
指導(dǎo)教師評語：
簽名：
年 月 日
外語文獻(xiàn)翻譯
原文：
3.4.1CAD HARDWARE
Computers
There are two major types of hardware used in a CAD system. Computer and input/output (I/O) devices. In the early days of CAD. Some commercial CAD systems used proprietary computers. Today, nearly all CAD software runs on a general-purpose computer.
Depending on the complexity of the CAD package, it may require a mainframe computer, a minicomputer, or simply a microcomputer. In general, the more functionalities a CAD system provides, the more powerful the computer needed. Three dimensional solid modelers require much more computing than do two-dimensional drafting systems; thus, they need more powerful computers. Systems that integrate engineering analysis or simulation packages generally are more computation-intensive. A powerful computer not only speeds up the response of a CAD system, but also can support multiple users without significant performance degradation.
Several other parameters and components concerning the computer also have to be considered.
CAD HARDWARE
random-access memory (RAM)capacity
permanent disk-storage capacity
special graphics accelerator
tape backups
RAM is the actual physical memory (vs. virtual memory)of a computer. A small memory capacity means slow processing due to frequent swapping between the physical memory and the virtual memory on disk. Because CAD is extremely storage demanding, disk capacity is important. Small disk capacity limits the system to the storage of only a few drawings. CAD is graphics-based and requires tremendous data processing. A graphics accelerator can drastically increase the performance of the system. Another component, the hard disk, is typically the major cost of a computer system. Therefore, it is not cost-justifiable to store all drawings on line on disk. Magnetic tape is still the most economical medium to use for off-line data storage. It is necessary for a CAD system to have a tape backup subsystem.
Currently, all levels of computers are used in CAD systems. Personal computers are used in low-cost,2-D drafting applications, and with the new power of these computers, hey are also being used for some 3-D solid modeling applications. Engineering workstations have been the mainstay in CAD, and are usually a single-user CAD workstation in a network. Minicomputers are used in multiuser CAD systems. Mainframes are used for large multiuser CAD systems to support real time simulation and engineering analysis. Sometimes, in a large corporation, all levels of CAD systems are implemented. All these systems are linked together through a hierarchical computer network.
3.4.2 Input. Output (I/O)Devices
Figure 3.7 shows the typical I/O devices used in a CAD system. Input devices are generally used to transfer information from a human or storage medium to a computer where ”CAD functions” are carried out. A keyboard is the standard input device used to transmit alphanumeric data to the system. Function keypads are also used to make input easier. Joysticks, track balls, and mousse are also used to manipulate a cursor. They can be used to position the graphic cursor(e.g. cross hair)on a monitor and feed back the location of an object on the monitor to the computer. Using these devices allows an operator to address terminal locations to interactively in reaching an accurate position. Mouses have been used extensively with windows and pull-down menus. They are easy to use for pointing; However, using a mouse to trace a curve is not an easy task.
There are three basic approaches to input an existing drawing;(1)model the object on a drawing,(2)digitize the drawing, or (3)scan the object. Digitizing is usually much easier than modeling. A digitizer is a device that translates the X-Y locations on a drawing than modeling. A digitizer is a device that translates the X-Y locations on a drawing into a digital and feeds that signal to a computer. Graphics scanners scan a drawing and convert it to a CAD-system-readable format. Some scanners have built-in character-recognition software that can convert characters on paper into ASCII codes. Another input device is a sketch pad called a graphics tablet. A graphics tablet is a special flat surface on which a user draws with a stylus. The location of the stylus is sent to the computer. The tablet is an absolute coordinate device. It is easy to implement overlay menus on the tablet and pull down menus on the screen to improve the operation. Currently. the tablet is the most popular input device used in CAD other than the keyboard.
The standard output device for CAD is a monitor display. Modern monitor displays are raster-scan display monitors. Similar to a TV monitor, an electron gun(Sony Trinitron uses three guns for three basic colors)sends an electronic beam to the front of the monitor. Easy display dot is called a pixel(picture element).For color displays, each pixel is represented by three closely located dots with red, green , and blue colors. The electronic beam selects the color elements and the intensity of each color element. The resolution of the monitor is determined by the number of different colors or gray scales displayable at each pixel, usually measured in bits, A 1-bit display can turn each pixel either ON or OFF.A gray scale has at least v2 bits. A 1-bit display can turn each pixel either ON or OFF.A gray scale has at least 2 bits which allow three light intensities plus an OFF (2*2).Usually, displays are 4 bits(16 colors),8 bits(256 colors),16 bits(thousands of colors),and 24bits (millions of colors).The electronic beam sweeps the screen from the top to the bottom line by line. Because the dot is lit for only a very short period of time, the sweep must be done very quickly in order not to have a flickering image. The refresh rate is a measure of how many times the monitor is redrawn in one second.
The computer does not draw directly on the monitor. Connecting the computer to the monitor is u-sually a RGB(red, green, blue)cable. Three separate signal lines are connected. On the graphics board in the computer are circuits to generate the analog signals required to drive the monitor. There is also a frame buffer that serves as memory to store the image. Each pixel on the screen has a corresponding address in the frame buffer. The data in the frame buffer are converted into the appropriate analog signal and sent to the monitor at the refresh rate. Separately, the computer writes directly to the frame buffer the image it intends to draw. The greater the display size and number of colors, the more frame buffer is needed. The frame buffer on the graphics board is made of random-access memory(RAM).
The calculator lend support toes to paint the software AutoCAD to make us can be with the sketch that the astonishing speed draw the engineering sketch or machine sketch and other with accuracy to sophisticate. The calculator paints to paint the different place, one of them with handicraft the paintings with out the diagram divide a step proceed of, because of but would sometimes appear the traditional handicraft the painting hour the problem of the impossible emergence. General circumstance bottom, usage the AutoCAD proceeds painting, control the precision painting and not that difficult, but want accurate then need the certain technique out the diagram. Us-
ually paint or outsing diagram to have no to need to change to measure to AutoCAD system worth make the modification with establish, take its the province worth can normal work, but have the special request, must modify the related system to change measure; Too sometimes the request of the diagram paper with make the diagram's way of doing the antinomy, and be to adopt the to make the diagram method to can't attain the request of the diagram paper, will adopt some techniqueiques to modify the related system to change to measure, and can make the calculator draw to attain the request of the diagram paper with output's sketch.
AutoCAD line type establishing of comparison At teaching of process inside would usually run into what this kind of circumstance, while establishing diagram layer, clearly established the point lin eationed, and consequently output to however investigate its reason for the solid lined, and is usually because of the line typed the establishing of comparison is not appropriate and cau-
sable. Should you so establish the comparison of what kind of line type? How to use the line type the comparison in the painting?
Usage AutoCAD painting, besides continuous line type( Continuous), the other line type is all from the solid line segment, blank segment, point series for or text this constituting. On-line type definition document the inside have already defined these line types the segment's standard length, and show on held the act or at print the machine\ painting output, each length and ex-
portation comparison with line type comparison direct proportion. When show or print, the painting boundary that customer that request, this hour establish is out of accordance with the painting boundary of the province difference big, on held the act show or paint output's line type would match the engineering graphics to will pass the changes line type comparison the system the method that change the deal, enlarge or contract all line types each a small segment of length, make the sketch made meet the request. In the Auto CAD, imply the adjustment line type the comparison's order: Overall situation line type comparison factor tie department exportation ratio for line type ratio factor, used foring the control not continuous line type. The Ltscale is right to have the object validity, Celtscale the province for to new object validating, twoly changing the deal w-
orth all for 1.
For use the line type that Auto CAD2002 painting, big part contain three kinds of forms,( such as: Comparison that Center, Center2, Center*2, Dashed, Dashed2, Dashed*2) the first is a half, the third line type for the standard form, the second line type that comparison that the first line type is the first line type of two times, if line type the comparison establish to is not suitable for, and would then make some exportation diagrams the line( such as the point lineation, dotted line...etc.) change into a solid line.
Two, line breadth the count of establishPass by what handicraft painting, its painting with outs the diagram is a synchronous proceeding of, now calculator painting, its painting with outs the diagram divide a step proceeds. Wether draw the construction engineering diagram or machine spare parts diagram, at print control that a work that exportation engineering drawing, the most is a line to print the drawing the breadth, line the type, color, seal a line breadth for, and eachly growing to line type all contain its cowgirl, in the AutoCAD painting process of the old edition, even defined the line type the width, its at see the diagram area can't also display the line type the width's differentiation.( not contain many righteousness lines the Pline)Width for color for can passing the diagram layer or set upping the line coming distinguish analysing the line.What research of current painting tries a, adopt of is this kind of method.But in the AutoCAD2002, add entity that" Lweight"( line type the width establish) order, provided the new function for customer, then make use of the entity characteristic to proceed the control, and establish the line breadth for the sketch, and make use of it can at hold the act to up show with print to output, control the entity's line breadth.2002 versions inside print to establish and can is divided into three part, and for printing machine belong to the sex to establish, print the style to establish respectively and the page establish.
Because of the model of breadth line the space is different from diagram manifestation of space paper result, in the model space therefore the elephant vegetable show, but in the diagram paper the space is then then to print the width to proceed to show, because of but we while drawing ske tch should know at the diagram line that true width established by line breadth of model space, and is not equal with object. When the line breadth is worth to establish to"0", it show with the minimum width( plain breadth of an elephant) on held the act, and the line breadth settle to other worth, then come showing with the worth specific value of plain width and true unit of elephant.
Three, the sketch output the establishing of comparison When we draw sketch that comparison that comparison output the sketch with us hour use different, can make originally text in the sketch that draw word exportation comparison for marking noting waiting in the output's sketch take placing changing, therefore at drawing the sketch before returning the beard make suring the sketch.For guaranteeing the sketch to output our want the literalness size, should when the text word establish usage following formula: The text word draws the high degree the = the text word output high degree* the sketch to output the comparison; The sketch outputs the comparison= output the diagram the length for of length( width)/ diagram.( width)
draw the width of the diagram line to also should consider this point, its to settle the width same as output the width to multiply by with its comparison worth.
From above practice with analyze to can see out, calculator painting and incompletelyresemble handicraft painting so synchronously paint with out diagram, therefore sometimes make with the diagram method can't attain the request of the diagram paper. Some in common use system that this demand we are deep into control the calculator to paint the theories, and can expertly control the operation method to change the deal with establish the technique, and can make the work of our painting more convenient, smooth, consumedly increase to paint the level with paint the efficiency.
譯文：
3.4.1CAD硬件
計算機
兩大主要類型的硬件使用于CAD系統(tǒng)，計算機和輸入/輸出設(shè)備。在CAD的早期，一些商業(yè)的CAD系統(tǒng)使用于專業(yè)計算機。如今，幾乎全部的CAD軟件都運用于普通用途的計算機。
根據(jù)CAD命令的復(fù)雜性，它可能需要一臺大型計算機，一臺迷你型計算機，或僅一臺微型計算機，大體上，CAD系統(tǒng)提供更好的功能性，需要更有強的計算機。三維空間建模比二維線型建模需要更好的計算機；因而，他們需要更有力的計算機。那使成整體分析的系統(tǒng)或一般模擬命令是更多更強的計算。一臺強的計算機不僅加速CAD系統(tǒng)的運行，而且也能支持多個使用者，并不降低使用性能。
幾個其他的參數(shù)和關(guān)于計算機的成分，也不得不被考慮。
隨機存取儲藏器容量
磁帶容量
專用圖形加速器
磁帶裝置
隨機存取儲藏器容量是計算機的實際的物理內(nèi)存（相對，虛擬內(nèi)存）。小的存取容量導(dǎo)致減慢是由于磁盤上的物理內(nèi)存和實際內(nèi)存的頻繁交換。因為，CAD是要求非常大非常多的，磁盤容量是重要的。對只有一些圖畫的儲藏小磁盤片能力極限系統(tǒng)， CAD是以圖形為基礎(chǔ)的并且需要巨大的數(shù)據(jù)處理，一個圖形加速器能大幅增加系統(tǒng)的表現(xiàn)。另外的一個成份 ， 硬盤, 典型地是計算機系統(tǒng)的主要費用。 因此,它不可置疑的儲藏所有線形圖形到硬盤上。 磁帶仍然是為脫機的數(shù)據(jù)儲藏使用的最節(jié)儉的媒體。有一卷音帶后緩子系統(tǒng)對CAD系統(tǒng)是必需的。
現(xiàn)在，所有水平的計算機在CAD系統(tǒng)中被用。 個人計算機被用在廉價的,二維的起草申請中 , 和由于這些計算機的新力量 , 他們也被用作在一些三維建模申請。 工程工作站在CAD中有主要的依靠, 和通常在一個網(wǎng)絡(luò)中是一個單一使用者CAD工作站.迷你計算機在數(shù)字CAD系統(tǒng)中被用。主機作為大的數(shù)字CAD系統(tǒng)是支援仿真模擬和分析。有時，在大的公司中，所有水平的CAD系統(tǒng)被實現(xiàn)。 所有的這些系統(tǒng)通過局域網(wǎng)絡(luò)被一起連接。
3.4.2 輸入/ 輸出 (輸入／輸出) 裝置
圖 3.7 表演在一個CAD系統(tǒng)中被用的典型輸入／輸出裝置。 輸入裝置通常用來轉(zhuǎn)移來自人或儲藏媒體的數(shù)據(jù)到一部計算機 "CAD功能" 在哪里實行。 一個鍵盤是標(biāo)準(zhǔn)的輸入裝置，過去一直送字母與數(shù)字并用的數(shù)據(jù)到系統(tǒng)。 功能按鍵區(qū)也使輸入更容易。 游戲操縱桿,追蹤球，而且鼠標(biāo)也用來操作光標(biāo)。 他們能用來放置一個監(jiān)視器上的繪畫似的光標(biāo) ( 舉例來說十字架頭發(fā)) ，而且回饋對計算機在監(jiān)視器上的目標(biāo)位置。使用這些裝置允許一個操作員交談式在到達(dá)一個正確的位置方面向終端指出位置。操縱桿和追蹤球在CAD系統(tǒng)中不被廣泛運用，由于很難的找到正確的位置。鼠標(biāo)被廣泛地用于窗口和下拉式菜單，他們?yōu)橹赋鍪侨菀资褂玫?然而, 使用一只鼠標(biāo)跟蹤曲線不是一件容易的工作。
有三個基本接近到輸入一幅已存在的圖畫;(1)一幅圖畫上的物體模型 , 數(shù)字化圖畫 , 或 (3) 掃描物體。 數(shù)字化通常比模型容易。一個數(shù)字化是進(jìn)入數(shù)傳信號之內(nèi)在一幅圖畫上翻譯 X- Y 軸位置的裝置和對一部計算機的追蹤信號。 圖形掃描機掃描一幅圖畫而且將它轉(zhuǎn)換成CAD系統(tǒng)可讀格式。 一些掃描機有內(nèi)建的字符識別軟件進(jìn)入美國信息交換標(biāo)準(zhǔn)代碼密碼之內(nèi)在紙上轉(zhuǎn)換字符。 另外的一個輸入裝置是一本手抄簿叫做圖形平板。 一個圖形平板是一個使用者用鐵筆拉出的特別的平面。鐵筆的位置被派遣去計算機。板是一個 同等的裝置。 實現(xiàn)平板上的疊菜單而且實現(xiàn)熒屏上的下拉式菜單改良操作是容易的。 現(xiàn)在，平板是在鍵盤之外的CAD系統(tǒng)中流行的輸入裝置
標(biāo)準(zhǔn)的輸出裝置對CAD監(jiān)視器顯示?，F(xiàn)代監(jiān)視器是試映圖- 掃描炫耀監(jiān)視器類似一個電視監(jiān)視器，一個電子槍 (Sony 單槍三束彩色映像管使用三只槍作為三基本顏色)送電子的光線給監(jiān)視器的前面。 每一個炫耀點叫做一個像素 (照片元素) 為彩色顯示，每個像素三點之間被接近地表現(xiàn)為紅色的，綠色的，和藍(lán)色的顏色。電子的光線選擇彩色元素和每種彩色元素的強度。監(jiān)視器的分辨率被熒屏上炫耀像素的數(shù)量所決定。（像素640*480，1024*1024）
和像素點大?。?4位，32位，等等）。色相和灰度的決議通過不同的色相或灰色刻度決定或開或關(guān)。一個灰色刻度至少2點允許三種強度光加號遠(yuǎn)的（2*2）。通常，閃光是4點（16位色），8點（256位色），16點（數(shù)千位色），和24點（數(shù)百萬色）。電子的光線從頂端到線的底線掃除熒屏。因為被為只有真正的短時段點亮, 掃除一定被非?？斓匾勒枕樞蜃霾灰幸婚W爍圖像。使比率尺寸是監(jiān)視器在一秒內(nèi)閃爍多少次來衡量。
計算機不直接的依賴監(jiān)視器。通常連接計算機到監(jiān)視器是 RGB(紅色的，綠色的,藍(lán)色的) 電纜。 三分開信號線被連接。 在計算機中的圖形是產(chǎn)生類比信號的線路。 也有一個視為記憶儲存圖像的緩沖。 熒屏上的每個像素在構(gòu)成緩沖中有一個相應(yīng)地址。 數(shù)據(jù)在構(gòu)成緩沖中被轉(zhuǎn)換成適當(dāng)?shù)念惐刃盘柌⑶宜徒o監(jiān)視器在那使比率。分開的，計算機直接的寫到構(gòu)成緩沖它想要拉出的像像。顏色的閃耀大小和數(shù)字愈比較很棒, 構(gòu)成緩沖是需要的也愈較多。 圖形上的構(gòu)成緩沖是隨機存取儲藏器（隨機存取儲藏器）
AutoCAD的系統(tǒng)變量
計算機輔助繪圖軟件AutoCAD使我們能以驚人的速度和精度繪制工程圖形或機械圖形以及其它復(fù)雜的圖形。計算機繪圖與手工繪圖不同之處，其中之一是繪圖與出圖是分步進(jìn)行的，因而有時會出現(xiàn)傳統(tǒng)手工繪圖時不可能出現(xiàn)的問題。一般情況下，使用AutoCAD進(jìn)行繪圖，掌握精確繪圖并不太難，而要準(zhǔn)確出圖則需要一定的技巧。通常繪圖或出圖無需對AutoCAD系統(tǒng)變量值作修改和設(shè)置，取其缺省值就能正常工作，但有特殊要求時，就必須修改相關(guān)的系統(tǒng)變量；也有的時候圖紙的要求與作圖的直觀做法相矛盾，當(dāng)采取直觀作圖法無法達(dá)到圖紙的要求時，就要采用一些技巧來修改相關(guān)的系統(tǒng)變量，才能使計算機繪出和輸出的圖形達(dá)到圖紙的要求。
2.1AutoCAD 線型比例的設(shè)置
在教學(xué)的過程中常常會碰到這種情況，在設(shè)置圖層時，明明設(shè)置了點劃線，結(jié)果輸出卻為實線，究其原因，往往是由于線型比例的設(shè)置不恰當(dāng)引起的。那么應(yīng)該設(shè)置什么樣的線型比例？如何在繪圖中使用線型比例？
????使用AutoCAD繪圖，除連續(xù)線型外，其它線型均由實線段、空白段、點或文本所構(gòu)成的系列。在線型定義文件中已定義了這些線型段的標(biāo)準(zhǔn)長度，在屏幕上顯示或在打印機\繪圖儀輸出時，每一小段長度與輸出比例和線型比例成正比。當(dāng)顯示或打印時，用戶設(shè)置的繪圖界限與缺省的繪圖界限差別較大時，在屏幕上顯示或繪圖儀輸出的線型會不符合工程制圖的要求，這時就要通過改變線型比例系統(tǒng)變量的方法，來放大或縮小所有線型的每一小段的長度，使所作圖形符合要求。在Auto CAD中，含有調(diào)整線型比例的命令：全局線型比例因子和局部線型比率因子，用于控制非連續(xù)線型的輸出比率。對所有對象有效，只對新對象有效，兩個變量的缺省值均為1。
????對于用Auto CAD2002繪圖，大部分的線型有三種形式, （如：Center、Center2、Center*2，Dashed、 Dashed2、Dashed*2）第一種為標(biāo)準(zhǔn)形，第二種線型的比例是第一種線型的一半，第三種線型的比例是第一種線型的兩倍，如果線型比例設(shè)置不適合，則會使一些輸出圖線（如點劃線、虛線等）變?yōu)橐粭l實線。
2.2線寬參數(shù)的設(shè)置
????過去手工繪圖，其繪圖和出圖是同步進(jìn)行的，如今計算機繪圖，其繪圖和出圖是分步進(jìn)行的。無論是繪制建筑工程圖還是機械零件圖，在打印輸出工程圖樣時，最主要的一項工作是控制打印圖樣的線寬、線型、顏色、封口，且每種線型都有其相應(yīng)的線寬，在舊版本的AutoCAD繪圖過程中，即使定義了線型寬度，其在視圖區(qū)也不能顯示出線型寬度的區(qū)別（不含多義線）。只能通過圖層或設(shè)定線的顏色來區(qū)分線的寬度。目前繪圖員考證的試題，采用的就是這種方法。而在AutoCAD2002中，新增了”Lweight”（線型寬度設(shè)置）命令，為用戶提供了新的功能，即利用實體特性進(jìn)行控制，為圖形的實體設(shè)置線寬，利用它可以在屏幕上顯示和打印輸出時，控制實體的線寬。2002版中打印設(shè)置可分為三個部分，分別為打印機屬性設(shè)置、打印樣式設(shè)置及頁面設(shè)置。
????由于線寬的模型空間和圖紙空間的顯示效果不同，在模型空間是以象素顯示，而在圖紙空間則是以打印寬度進(jìn)行顯示，因而我們在繪制圖形時應(yīng)認(rèn)識到在模型空間由線寬設(shè)置的圖線，與對象的真實寬度并不相等。當(dāng)線寬值設(shè)為“0”時，它在屏幕上以最小的寬度（一個象素寬）顯示，線寬定為其它值時，則以象素寬度與真實單位值的比值來顯示。
2.3圖形輸出比例的設(shè)置
當(dāng)我們繪制圖形的比例與我們輸出圖形時使用的比例不同時，就會使原來繪制的圖形中的文字標(biāo)注等在輸出的圖形中發(fā)生變化，因此在繪制圖形之前還須確定圖形的輸出比例。為了保證圖形輸出時文字的大小是我們所想要的，應(yīng)在文字建立時使用如下公式：文字繪制高度=文字輸出高度*圖形輸出比例；圖形輸出比例=輸出圖幅的長度（寬度）/圖幅的長度（寬度）。
同理，繪制圖線的寬度也應(yīng)該考慮這點，其給定寬度等于輸出寬度乘以其比例值。
????從以上實踐和分析可看出，計算機繪圖并不完全像手工繪圖那樣同步繪圖和出圖，因此有時用直觀作圖法無法達(dá)到圖紙的要求。這就需要我們深入掌握計算機繪圖理論，并能熟練地掌握一些常用的系統(tǒng)變量的使用方法和設(shè)置技巧，才能使我們的繪圖工作更為便利、順暢，大大地提高繪圖水平和繪圖效率。
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