0275-氣體渦輪流量計(jì)的設(shè)計(jì)與制造【全套5張CAD圖】

0275-氣體渦輪流量計(jì)的設(shè)計(jì)與制造【全套5張CAD圖】,全套5張CAD圖,氣體,渦輪流量計(jì),設(shè)計(jì),制造,全套,cad 附錄1：中英文翻譯 CAD CAM and Applications A Brief History of CAD Before 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 earl, 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 hap 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, enables a CAD system 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-flame 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 information; 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 w ecessary 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 CAD A 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 hardware and Provides basic functions such as creating and removing operation tasks, ontrolling the progress of tasks, allocating hardware resources among 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 consists 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 the 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 Design Computer 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 drawings of the final design. Two-dimensional drawing is one area in which computer methods can offer 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 Two-Dimensional Drawings CAD makes possible multiview 2D drawings, with an endless possibility of views in a range of scales from microns 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 Drawings Designers have even more freedom with the advent of 3D modeling. They can create 3D parts and manipulate them in endless variations to achieve the desired results. Through finite element analysis (FEA),stresses can be applied to a computer model and the results graphically displayed, giving the designer quick feedback on any inherent problems in a design before the creation of a physical prototype. 3D models can be created in wire-flame, in surfaces or in solid form. In wire-frame, lines and arcs form edges that generate the model(Fig,8-la).The result is a 3D form that can be viewed from any location but is still only a skeletal form. Creating a surface stretches a skin over the skeleton (Fig,8-lb).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 models, The computer thinks the solid model is a solid mass so it can be ”drilled,” ”±m(xù)achined,” or ”welded” as if it were an actual physical part. It can be made out of any material and can take on that material`s characteristics, thereby allowing calculations of mass to be made. CAD`s Benefits The benefits of computer use in drafting and design tasks are impressive: increased speed, greater accuracy, reduction of hardcopy storage space as well as better recall, enhanced communication capabilities, improved quality and easier modification. Speed A personal computer used in industry can perform a task at an average rate of 33 million operations per second; newer computers 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. Accuracy Because the computer`s data is stored in an electronic form, it can be sent to a 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 drawings. The data can also be sent to a plotter to produce the familiar paper drawing, via a direct link to a computer-aided manufacturing(CAM)machine or via telephone to anywhere around the globe. You no longer have to mail drawings, risking damage and loss; they can now be at their destination instantly via the telecommunications network. Quality The computer always retains the data in the form in which it was first created. It can repeat the same output of data continuously without regard to fatigue. Lines will always be crisp and clear, with uniform line weight, and text will always be legible. The computer doesn`t alter its output quality because of a wild weekend or a late night watching the game. Modification The computer data is stored in a format that allows easy modification to any facet of a drawing and gives instant feedback to the user. When something is drawn once, it never has to be drawn again because the object in question can be duplicated, stretched, sized, and changed in many ways without having to be redrawn. Except for the initial cost to purchase a CAD workstation, CAD`s only disadvantage is a small one because it can be so easily overcome. Because the drawing is stored in an electronic format and not a paper format, it is possible to erase a drawing file easily. That`s why it is essential to train yourself in good CAD practices to avoid an accidental erasure. And-although an ounce of prevention truly is worth a pound of cure, there are even ways of unerasing files that are usually Successful if you follow the correct procedures. So relax ! Computer Aided Manufacturing When a design has frozen, manufacturing can begin. Computers have an important role to play in many aspects of production. Numerically controlled (NC) machine tools need a part program to define the components being made; computer techniques exist to assist, and in some cases virtually automate the generation of part programs. Modem shipbuilding fabricates structures from welded steel plates that are cut from a large steel sheet. Computer-controlled flame cutters are often used for this task and the computer is used to calculate the optimum layout of the components to minimize waste metal. Numerically controlled pipe-bending machines are able to operate directly from part programs generated by pipe-routing software. Printed circuit board assembly can also be improved by computer methods. Quality is maintained by computer-controlled automatic test equipment that diagnoses faults in a particular board and rejects defective boards from the assembly line. Computers are used extensively to plot the artwork used to etch printed circuit boards and also to produce part programs for NC drilling machines. One of the most important manufacturing function is stock and production control. If the original design is done on a computer, obtaining lists of material requirements is straightforward. Standard computer data processing methods are employed to organize the work flow and order components when required. Computer Aided Part Programming Part programming software is used to ease programming for CNC machines when a complex part geometry requires calculation of a large number of tool positions. Part programming software is usually incorporated into a family of CAM (Computer Aided Manufacturing) software. Some CAM software is associated with CAD (Computer Aided Design) software into CAD/CAM stations .Then the CAM software can use the CAD files as a source of data, which speeds up the programming process. Part programming software is user-friendly, meaning the programmer does not have to know the computer programming language or its operating system. It uses screen menus to lead the user through the programming process. Data can be entered via the keyboard, the mouse, or the function Keys. Experienced programmers can use built-in macro capabilities and advanced techniques such as a family of parts to become even more productive. ilt-in software with communications capability. Good part programming software is capable of: (1)Establishing the machining parameters and tooling for a particular machine or job. (2)Defining the geometry and tool path. (3)Code generation-enabling the programmer to define what code is to be generated and how it is output to the machines. (4)Communication enabling the programmer to use standard communications protocols or create his or her own. NC Cutter-Path Verification Before a part is machined, the part program needs to be verified. The purposes of verification are orkpiece．A dry cut can detect gross programming mistakes, but not the detailed geometric ones．Another approach is to actually machine a prototype．Typically, a prototype part is machined in wax, machining plastic, wood, foam, or some other soft material．The actual geometry is then measured and compared with the design specification．Because material property is critical in determining the cutting condition，this approach can verify only the geometry． When a part program is generated using a CAD-based system, a graphic output of the cutter path may be produced by the software．By visual inspection，cutter-path abnormalities may be detected． Figure 9-2 shows such an approach in a commercial CAD／CAM system．In an advanced system，a solid model may be used to generate a realistic picture of the workpiece，tool and the finished part． Real-time simulation of the cutting process can be displayed on screen．However, most simulations are purely geometry-based, where the cutting condition is not considered． Computer Aided Process Planning Recent developments in computer-aided process planning have focused on eliminating the process planner from the entire planning function．Computer-aided process planning can reduce some of the decision making required during a planing process．It has the following advantages： (1)It can reduce the skill required of a planner． (2)It can reduce process-planning time． (3)It can reduce both process-planning and manufacturing costs． Procrss planning is the critical bridge between design and manufacturing. Design informantion can be translated into manufacturing language only through process planning. Today,both computer-aided design(CAD)and manufacturing(CAM)have been implemented. Integrating, or bridging, these function requires automated process planning. Group Technology Any new component design needs its own unique identification number, usually the drawing nh drawing number is allocated by a coding system and each digit has meaning. If the code number is known, many of the component features can be deduced without reference to the drawing. Materials Requirement Planning Essentially this is the simple idea of combining the master production schedule with bills of materials to determine exactly the amount of raw materials components, etc., needed. This amount is compared with current stocks and used to calculate orders for new materials. The information is then combined with priority planning to ensure that correct orders go out in the correct sequence. Materials requirement planning(MRP)techniques have been available for some time, but with the advent of computers much more, accurate informationty in stock, unit of measure(feet of tubing, number of screws, etc.)minimum stock level, lead time of purchased or manufactured in-house. Robotics Robots are mechanical arms controlled by computer programs. Changing the program changes the set sequence of movements. The arms are articulated and there are two basic types of joints, revolute and prismatic. Revolute joints involve rotation about an axis and prismatic joints involve a slide of some kind, motion in a straight line (Fig.9-5).Each joint has its own servomotor, velocity and position transducer and is also called a degree of freedom. Different tools or end effectors can be attached to the end of the arm for different applications; for example, mechanical assembly, paint spraying and welding. Computer Integrated Manufacturing Today`S industry compete is in a truly international marketplace. Efficient transportation networks have created a ”world market” in which we participate on a daily basis. For anomers by allowing last-minute engineering-design changes without affecting shipping schedules or altering product quality. Most manufacturing companies look toward CAD,CAM and CIM to provide this flexibility in their manufacturing system. Today, the use of computers in manufacturing is common. Manufacturing system are being designed that not only process parts automatically, but also move the parts form machine to machine and sequence the ordering of operations in the system. Flexible Manufacturing Systems A flexibte manufacturing system, or FMS as they are more commonly known, is a reprogrammable manufacturing system capable of producing a variety of products automatically. Since Henry Ford first introduced and modernized the transfer line, we have been able to perform a variety of manufacturing operations automatically. However, altering these systems to accommodate even minor changes in the product has been quite taxing. Whole machines might have to be introduced to the system while other machined or components are modified or retired to accommodate small changes in a product. In today`s competitive marketplace, it is necessary to accommodate customer changes or the customer will find so (1)Job shop type systems were capable of producing a variety of product, but at a high cost. (2)Transfer lines could produce large volumes of a product at a reasonable cost, but were limited to the production of one, two, or very few different parts. The advent of numerical control(NC)and robotics has provided us with reprogramming capabilities at the machine level with minimum setup time. NC machines and robots provide the basic physical building blocks for reprogrammable manufacturing systems. FMS Equipment In order to meet the requirements of the definition of an FMS, the basic processing in the system must be automated. Because automation must be programmable in order to accommodate a variety of product-processing requirements, easily alterable as well as versatile machines must perform the basic processing. For this reason, CNC turning centers(Fig.9-7),CNC machining centers, automated part inspection system, and robotic workstatio more tools(right-hand turning tools, left-hand turning tools, boring bars, drilling, and so on).The automatic tool changer and storage capabilities of NC machines make them natural choices for material-processing equipment. Parts must also be moved between processing stations automatically. Several different types of material-handling systems are employed to move these parts from station to station. The selection of the type of material-handling system is a function of several system featHres．The material-handling system, first, must be able to accommodate the load and bulk of the part and perhaps the part fixture. Large, heavy parts require large. powerful handling sy. A conveyor or automatic guided vehicle (AGV)system can be expanded to include miles of factory floor. 計(jì)算機(jī)輔助設(shè)計(jì)制造與應(yīng)用 計(jì)算機(jī)輔助設(shè)計(jì)的簡要?dú)v史 在我們講述CAD的基本理論之前，先說說它的簡史是比較合適的。CAD是計(jì)算機(jī)時(shí)代的產(chǎn)品。它從早期的計(jì)算機(jī)繪圖系統(tǒng)發(fā)展到現(xiàn)在的交互式計(jì)算機(jī)圖形學(xué)。兩個(gè)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(jìn)行交互操作。CAD與初次出現(xiàn)的Nc和APT(自動(dòng)編程工具)碰巧同時(shí)問世。后來，x—Y繪圖儀作為計(jì)算機(jī)繪圖的標(biāo)準(zhǔn)硬拷貝輸出裝置使用，一個(gè)有趣的現(xiàn)象是x—Y繪圖儀與Nc鉆床具有相同的基本結(jié)構(gòu)，除了繪圖筆被NC機(jī)床上的主軸刀具替代之外。 20世紀(jì)70年代，三維實(shí)體建模的發(fā)明標(biāo)志著CAD一個(gè)新時(shí)代的開始。過去的三維線框模型僅用其邊界來表達(dá)一個(gè)物體。這在某種意義上是含糊的，一個(gè)簡單的模型可能有幾種解釋。同時(shí)也無法獲得一個(gè)模型的體積信息。實(shí)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(dá)上是強(qiáng)有力的，但仍然存在許多缺陷。例如，這種系統(tǒng)要有極強(qiáng)的計(jì)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的應(yīng)用。直到20世紀(jì)80年代中期，實(shí)體建模開始介人設(shè)計(jì)環(huán)境。今天實(shí)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(gè)人計(jì)算機(jī)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(jì)。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(gè)人機(jī)CAD軟件包的引入，使小型公司乃至個(gè)人可以擁有并使用CAD系統(tǒng)。到1