机械工程英语46-58课中英对照翻译 施平编.docx

46课Computer-aided design（CAD）involves the use of computers to create design drawings and product models. Computer-aided design is usually associated with interactive computer graphics（known as a CAD system）.计算机辅助设计(CAD)涉及到电脑的使用来创建设计图纸和产品模型。计算机辅助设计通常是与交互式计算机图形学(称为CAD系统)。Computer-aided design systems are powerful tools and are used in the mechanical design and geometric modeling of products and components计算机辅助设计系统是强大的工具,用于产品的机械设计和几何建模和组件In CAD，the drawing board is replaced by electronic input and output devices. When using a CAD system，the designer can conceptualize the object to be designed more easily on the Graphics screen and can consider alternative designs or modify a particular design quickly to meet the necessary design requirements or changes.在CAD图纸被电子输入和输出设备。当使用CAD系统中,设计人员可以概念化设计的对象更容易在图形屏幕上,可以考虑替代设计或修改一个特定设计迅速满足必要的设计要求或更改。The designer can then subject the design to a variety of engineering analyses and can identify potential problems （such as an excessive load or deflection）. The speed and accuracy of such analyses far surpass what is available from traditional methods.设计师可以设计各种各样的工程分析和可以识别潜在的问题(如过度负荷或偏转)。这种分析的速度和准确度远远超过可以从传统的方法是什么。Draft productivity rises dramatically. When something is drawn once，it never has to be drawn again.草案生产率大幅上升。当有了一次,它从来没有再画。it can be retrieved from a library ,and can be duplicated, stretched, sized, and changed in many ways without having to be redrawn。Cut and paste techniques are used as labor-saving aids.它可以从库检索,可以复制,拉伸,大小,改变在许多方面不用redrawn.Cut粘贴技术用作省力艾滋病。CAD makes possible multiview 2D drawings ，and the drawings can be reproduced in different levels of reduction and enlargement.CAD使可能的多视图2 d图纸,图纸可以复制在不同程度的减少和扩大。It gives the mechanical engineer the ability to magnify even the smallest of components to ascertain if assembled components fit properly.它让机械工程师的能力放大甚至最小的组件来确定如果组装组件配合得当。Parts with different characteristics，such as movable or stationary ，can be assigned different colors on the display.部分具有不同特点,如移动或静止不动的,可以指定不同的颜色显示。Designers have even more freedom with the advent of 3-D parts and manipulate them in endless variations to achieve the desired results.设计师有更多自由随着3 d部分和操纵他们无穷无尽的变化来获得期望的结果。Through finite element analysis ，stresses can be applied to be 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.通过有限元分析,压力可以被应用到一个计算机模型,结果以图形方式显示出来,给设计师提供快速反馈任何固有的问题在设计物理原型的创建。In addition to the designs geometric and dimensional features，other information （such as a list of materials，specification ，and manufacturing instructions）is stored in the CAD database. Using such information ,the designer can then analyze the economics of alternative designs.除了设计的几何和空间特性,其他信息(如材料的清单,规范,和生产指令)存储在CAD数据库。使用这些信息,设计师可以分析替代的经济设计。Computer-aided manufacturing(CAM) involves the uses of computers and computer technology to assist in all the phases of manufacturing a product，including process and production planning，machining，scheduling，management ，and quality control. Computer-aided design and computer-aided manufacturing are often combined into CAD/CAM systems.计算机辅助制造(CAM)涉及计算机和计算机技术的使用,协助生产一个产品的所有阶段,包括过程和生产计划、加工、调度、管理和质量控制。计算机辅助设计和计算机辅助制造通常结合到CAD / CAM系统。This combination allow the transfer of information from the design stage into the stage of of planning for the manufacture of a product，without the need to reenter the data on part geometry manually.这种组合允许转让信息从设计阶段的阶段,规划产品的生产,而不需要手动重新输入数据部分几何。The database developed during CAD is stored； then it is processed further，by CAM，into the necessary data and instructions for operating and controlling production machinery，material-handling equipment，and automated testing and inspection for product quality.在CAD开发的数据库存储;然后进一步处理,通过凸轮,到所需的数据和指令操作和控制生产机械、设备来源,自动化测试和检验产品质量。In machining operations，an important feature of CAD/CAM is its capability to describe the tool path for various operations，such as NC turning，milling，and drilling.在加工操作中,CAD / CAM的一个重要特性是其能力来描述刀具轨迹的各种操作,如数控车削、铣削和钻孔。The instructions （programs）are computer generated，and they can be modified by the programmer to optimize the tool path .计算机生成的指令(程序),他们可以由程序员修改优化刀具轨迹。The engineer or technician can then display and visually check the tool path for possible tool collisions with fixtures or other interferences. The tool path can be modified at any time，to accommodate other part shapes to be machined.工程师或技术员可以显示和视觉检查刀具轨迹的可能的工具与设备碰撞或其他干扰。工具路径随时可以修改,以适应其他部分形状加工。Some typical applications of CAD/CAM are：（a）programming for NC，CNC，and industrial robots；（b）design of tools and fixtures and EDM electodes；（c）quality control and inspection，for instance，coordinate-measuring machines programmed on a CAD/CAM workstation；（d）process planning and scheduling ；and（e）plant layout.一些典型的CAD / CAM的应用是:(a)为数控编程,数控,和工业机器人;(b)设计的工具和夹具和EDM electodes;(c)质量控制和检查,例如,坐标测量机CAD / CAM工作站程序;(d)工艺规划和调度;(e)工厂的布局。The emergence of CAD/CAM has had a major impact on manufacturing，by standardizing product development and by reducing design effort，tryout，and prototype work；it has made possible significantly reduced costs and improved productivity.CAD / CAM的出现已经对生产产生重大影响,通过标准化产品开发和减少设计工作,调试,和原型工作;它可能显著降低成本和提高生产力。The two-engine Boeing 777 passenger airplane，for example, was designed completed by computer（paperless design ）. The plane is constructed directly from the CAD/CAM software developed（an enhanced CATIA system）and no prototypes or mockups were built ，such as were required for previous models.双引擎的波音777客机,例如,设计完成的计算机(无纸化设计)。飞机构造直接从开发的CAD / CAM软件(一个增强的CATIA系统)和任何原型和模型建立,如需要以前的模型。48课Process planning is the determination of how a particular part will be manufactured in the shop. It consists of breaking manufacturing process for the part into small steps，and then determining the optimum method of achieving that manufacturing step. This includes determining the type of manufacturing process to use ，as well as the machining parameters for that particular process. It also includes determining a sequence of operations for the individual manufacturing actions that attempts to optimize a combination measure of manufacturing time and cost.工艺设计是确定如何制造一个特定部分的商店。它包括生产过程的部分分解成小步骤,然后确定最优方法制造的实现步骤。这包括确定生产过程使用的类型,以及加工参数对这个特定的过程。它还包括确定个人的操作序列生产行动,试图优化相结合的制造时间和成本。The essence of the process planning task can be reduced to five basic steps. First，the required operations must be determined by examining the design data and employing basic machining data （such as that square parts cannot be made on lathes ）.流程规划任务的本质可以概括为五个基本步骤。首先,所需的操作必须由检查设计数据和使用基本的加工数据(如广场部分不能在车床)。Second，the machines required for each operations must be determined. This selection depends on knowledge of machine factors，such as availability，machining rate ，size，power，and torque.第二,必须确定每个所需的机器操作。这个选择取决于机器的知识因素,如可用性、加工速度、大小、功率和扭矩。Third，the required tools for each identified machine must be determined.第三,必须确定每个确定机所需的工具。Fourth，the optimum cutting parameters for each selected tool must be determined. These parameters include feed rate ，cutting rate ，depth of cut，and so forth. This determination depends on design data, such as material and surface roughness specifications，and on tool-cutting behavior.第四,最优切削参数为每个选定的工具必须确定。这些参数包括加料速度、切削速度、深度减少,等等。这决心取决于设计数据,材料和表面粗糙度等规范,tool-cutting行为。Finally，an optimal combination of these manufacturing process must be determined. The optimum is the process plan that minimizes some measure of manufacturing time and cost. This provide a detailed plan for the economical manufacture of the part.最后,必须确定这些生产过程的最优组合。最优过程计划,最大限度地减少一定的制造时间和成本。这提供了一个详细的计划经济生产的部分。Traditionally process planning is performed manually by highly experienced process planners who possess an in-depth knowledge of the manufacturing process involved and the capabilities of the shop floor facilities. Because of the experience factor involved in process planning and in the absence of standardization of the process, conventional process planning has largely been subjective. Moreover，this activity is highly labor intensive. Rather than carrying out an exhaustive analysis and arriving at optimum values which could be time consuming，process planners often tend to play safe by using conservative values and this situation would invariably lead to no-optimal utilization of the manufacturing facilities and longer lead times.传统工艺设计是由经验丰富的手动执行过程计划拥有深入的知识生产过程和车间设备的功能。因为经验因素参与过程的计划和在缺乏标准化的过程中,传统的工艺设计在很大程度上是主观的。此外,这个活动是高度劳动密集型的。而不是进行详尽的分析和到达最优值可以耗费时间,过程规划者往往玩安全使用保守的价值观,这种情况总是会导致no-optimal生产设施的利用率和较长的交货期。The need for shorter lead times，satisfying varied customer demands on the product variety and the optimum use of manufacturing facilities prompted research organizations and industries to automate many functions in the manufacturing process. Harnessing the power of the computer is extremely advantageous in process planning since vast amount of data needs to be used for making the right decision for planning the manufacturing operations.需要更短的交货期,满足不同客户需求的产品种类和生产设备的最佳使用促使研究组织和工业自动化生产过程的许多功能。利用计算机的力量是极其有利的过程规划以来,大量的数据需要用于制造业务的计划做出正确的决定。Computer-aided process planning（CAPP）involves the use of computers to automate this process. The design data would typically be the finished part design file from the CAD system . As part of the realization of the gains of CIM，the CAM process are designed to start with this CAD design file as their input. This insures a continuity of information flow from design engineering to manufacturing engineering. It also provides an exactly accurate and well-structured form of input to manufacturing with no additional cost to design engineering . It is this well-structured input that allows for the use of computer-aided processes in manufacturing engineering.计算机辅助工艺规划(CAPP)涉及到电脑的使用自动化这个过程。设计数据通常是完成部分设计文件从CAD系统。作为实现的收益的一部分CIM,凸轮设计过程开始与这个计算机辅助设计文件作为输入。这确保连续性信息流从工程设计到制造工程。它还提供了一个完全准确、结构形式的输入制造没有额外成本设计工程。正是这种结构良好的输入允许使用计算机辅助制造工程流程。There are two basic approaches to computer-aided process planning ，i.e. variant or generative，which are briefly discussed below.计算机辅助工艺设计有两种基本方法,即。变体或生成,下面简要讨论。The first of these is variant or retrieval method. In this method，the computer makes a search through its store of number of standard or partially completed process plans that have been previously developed by human planners. Using the current design data supplied by the CAD system，it searches for a plan that was based on a part of similar design. This search can make effective use of group technology design coding to simplify the search for similar code numbers，and hence for similar part designs. This original plan is then modified or completed by the human planners to suit the exact requirements of the current part design. The use of a computer and group technology to search for the most similar past design，and to retrieve the process plan for that design ，significantly reduces the work required of the process planners. Their task becomes one of modifying the exist plan to suit the particular dimensions of the current part. They are required to perform the entire process planning method only in the case of a completely new part design.第一个是变体或检索方法。在这种方法中,计算机搜索的商店数量的标准或部分完成过程的计划,已经被人类以前开发的规划者。使用当前设计CAD系统提供的数据,搜索一个计划,是基于类似的设计的一部分。这个搜索可以有效利用成组技术设计编码简化搜索相似的代码数量,从而为类似的部分设计。这个原计划然后修改或完成人类的规划者,以适应当前的确切需求部分的设计。使用计算机和组技术来寻找最相似的设计,和检索流程规划设计,显著减少所需的工作流程的规划者。他们的任务成为修改计划以适应当前的特定维度存在的部分。他们只需要执行整个过程规划方法的一个全新的部分设计。The second method of computerized process planning is the generative method. In this method，a process plan is automatically generated on the basis of the same logical procedures that would be followed by a traditional process planners in making that particular part. However，the generative method is complex because it must contain comprehensive and detailed information of the part shape and dimensions ；process capabilities；selection of the manufacturing methods ，machinery ，and tools；and the sequence of operations to be performed.计算机化工艺规划的第二个方法是生成方法。在这种方法中,一个过程的计划的基础上自动生成相同的逻辑程序,紧随其后的是一个传统工艺规划师在这个特定的部分。然而,生成方法是复杂的,因为它必须包含全面和详细的信息部分的形状和尺寸,过程能力;制造方法的选择,机械,工具,操作的顺序被执行。The generative method is capable of creating a new plan instead of having to use and modify an existing plan（as the variant method must）. Although generally used less commonly than the variant method，this method has such advantages as （a）flexibility and consistency for the process planning for new parts and （b） higher overall planning quality.生成方法能够创建一个新计划而不是使用和修改现有计划(如变异方法必须)。虽然通常使用一般低于变异方法,该方法具有灵活性(a)和一致性的过程规划新部件和(b)质量更高的总体规划。50课Today, computer numerical control machine tools are widely used in manufacturing enterprises. Computer numerical control is the automated control of machine tools by a computer and computer program.今天,计算机数控机床广泛应用于制造企业。计算机数控机床的自动控制是计算机和计算机程序。The CNC machines still perform essentially the same functions as manually operated machine tools，but movements of the machine tool are controlled electronically rather than by hand. CNC machine tools can produce the same parts over and over again with very little variation. They can run day and night，week after week，without getting tired. These are obvious advantages over manually operated machine tools，which need a great deal of human interaction in order to do anything.数控机器仍执行相同的函数作为手动机床,但机床控制电子的运动,而不是用手。数控机床可以产生相同的部分,一次又一次变化很少。他们可以日夜不停地运转,一周又一周,没有累了。这些明显的优势在手动机床,需要大量的人工交互为了做任何事。A CNC machine tool differs from a manually operated machine tool only in respect to the specialized components that make up the CNC system. The CNC system can be further divided into three subsystems：control，drive，and feedback. All of these subsystems must work together to form a complete CNC system.数控机床不同于一个手动机床只有在尊重专业的组件构成的数控系统。数控系统可以进一步分为三个子系统:控制、驱动,和反馈。所有这些子系统必须共同努力,形成一个完整的数控系统。1. control system1。控制系统The centerpiece of the CNC system is the control. Technically the control is called the machine control unit（MCU），but the most common names used in recent years are controller，control unit，or just plain control. This is the computer that stores and reads the program and tells the other components what to do.数控系统控制的核心。技术控制称为机控制单元(MCU),但近年来最常用的名字是控制器,控制单元,或者就是简单的控制。这是计算机存储和读取程序,告诉其他组件该做什么。2. Drive system.2。驱动系统。The drive system is comprised of screws and motors that will finally turn the part program into motion. The first component of typical drive system is a high-precision lead screw called a ball screw（Fig.50.1）. Eliminating backlash in a ball screw is very important for two reasons. First，high-precision positioning can not be achieved if the table is free to move slightly when it is supposed to be stationary. Second，materials can be climb-cut safely if the backlash has been eliminated. Climb cutting is usually the most desirable method for machining on a CNC machine.螺丝和汽车的传动系统是由部分程序,最终将变成运动。第一个组件的典型的驱动系统是一种高精度丝杠称为滚珠丝杆(Fig.50.1)。消除反应在滚珠螺杆是非常重要的两个原因。首先,不能实现高精度定位如果表是免费的移动略当它应该是固定的。第二,材料可以安全地同向如果反弹已经消除。爬上切割通常是最可取的方法在数控加工机器。Drive motors are the second specialized component in the drive system. The turning of the motor will turn the ball screw to directly cause the machining table to move. Several types of electric motors are used on CNC control systems，and hydraulic motors are also occasionally used.驱动电机驱动系统中的第二专业组件。电动机的转动将滚珠螺杆直接导致加工表。几种类型的电机是用在数控控制系统和液压马达也偶尔使用。The simplest type of electric motor used in CNC positioning systems is the stepper motor（sometimes called a stepping motor）. A stepper motors rotates a fixed number of degrees when it receives an electrical pulse and then stops until another pulse is received. The stepping characteristic makes stepper motors easy to control.最简单的类型的电动机用于数控定位系统是步进电机(有时称为步进电机)。步进电机旋转固定数量的度当它收到一个电脉冲,然后停止,直到接收到一个脉冲。步进特性使步进电机容易控制。It is more common to use servomotors in CNC systems today. Servomotors operated in a smooth ，continuous motionnot like the discrete movements of the stepper motors. This smooth motion leads to highly desirable machining characteristics，but they are also difficult to control. Specialized hardware controls and feedback systems are needed to control and drive these motors. Alternating current（AC）servomotors are currently the standard choice for industrial CNC machine tools.这是今天使用伺服电机在数控系统中更为普遍。伺服电机运行在一个光滑、连续的活动,如离散运动的步进电机。这光滑的运动导致高度理想的加工特点,但他们也难以控制。需要专门的硬件控制和反馈系统控制和驱动这些汽车。交流电伺服电机目前工业数控机床的标准选择。3. Feedback System3。反馈系统The function of a feedback system is to provide the control with information about the status of the motion control system，which is described in Figure 50.2.反馈系统的功能是为控制提供运动控制系统的状态信息,如图50.2所示。The control can compare the desired condition to the actual condition and make corrections. The most obvious information to be fed back to the control on a CNC machine控制可以比较所需的条件的实际条件和改正。最明显的信息反馈给控制数控机器上tool is the position of the table and the velocity of the motors. Other information may also be fed back that is not directly related to motion control，such as the temperature of the motor and the load on the spindlethis information protects the machine from damage.工具的位置表和汽车的速度。其他信息也可以反馈,不是直接关系到运动控制,如电动机的温度和负载spindle-this信息保护机器免受损坏。There are two main types of control systems：open-loop and closed-loop. An open-loop system does not have any device to determine if the instructions were carried out. For example，in an open-loop system，the control could give instructions to turn the motor 10 revolutions. However，no information can come back to the control to tell it if it actually turned。All the control knows is that it delivered the instructions. Open-loop control is not used for critical systems，but it is a good choice for inexpensive motion control systems in which accuracy and reliability are not critical.主要有两种类型的控制系统:开环和闭环。一个开环系统没有任何设备来确定指令进行。例如,在一个开环系统,控制可以给指令将电动机10革命。然而,任何信息可以回到控制告诉它,如果它实际上turned.All控制知道是它的指示交付。开环控制不用于关键系统,但这是一个不错的选择廉价的运动控制系统的精度和可靠性并不是最关键的。Closed-loop feedback uses external sensors to verify that certain conditions have been met. Of course，position and velocity feedback is of primary impo