虚拟制造在齿轮生产中的应用外文翻译、中英文翻译、机械类外文文献翻译

外文原文： Application of virtual manufacturing in generation of gears Received: 29 November 2004 / Accepted: 5 May 2005 / Published online: 24 November 2005 Spfinger-Verlag.London Limited 2005 Abstract The manufacturing process of gears is fairly complicated due to the presence of various simultaneous motions of the cutter and the job. In this paper, an attempt is made to generate meaningful design data for spur and helical gears and the corresponding rack form cutter necessary for the manufacturing. Using this information, solid models for the cutter and blank are developed and finally gear-manufacturing processes are simulated in a virtual manufacturing environment. The user has the option to choose between designs and manufacture mode at will. The integrated process may also help to develop an optimized product. For better understanding of the operational principle, an animation facility in the form of a movie is included in the package. Keywords Virtual manufacturing； Animation； Gear generation 1 Introduction A gear is a very common machine element in mechanical engineering applications. However, manufacturing of the gear seems to be fairly complicated even to the person having thorough technical knowledge in the related field. The conventional gear generation processes like forming, shaping, hobbing, etc. are usually represented in two-dimensional sketch. There may be some components that are not adequately described by the two-dimensional approach. In the case of gear generation, it may be difficult to understand the complex geometries and the manufacturing arrangement with the help of 2D models. These limitations can be partially overcome and understanding will be more meaningful if one uses 3D solid models instead. However, the development of the models using 3D solids may not always ensure the clarity of the complex gear generation process unless one uses animation to represent tile motion of the gear blank and the gear cutter. This can be achieved very efficiently with the help of the virtual manufacturing technique. It is a technology to create a virtual environment on the computer screen to simulate the physical world. The knowledge base and expertise gained from the work in the virtual environment enables the user to apply them more meaningfully in real life situations. A host of literature is available on virtual manufacturing in different areas among which some of the recent and important works are referred below. Tesic and Baneljee 1 have worked in the area of rapid prototyping, which is a new technology for design, visualization and verification. Graphical user interfaces, virtual reality technologies, distillation, segregation and auto interpretation are some of the important features of their work. Balyliss et al. 2 dealt with the development of models in a virtual environment using the virtual reality technologies providing an outstanding 3D visualization of the object. In 1994, G.M. Balyliss et al. 3 presented theoretic solid modeling techniques using the VM tools, like VP, MI, (virtual reality manufacturing language) and 3D Sludio Max. They have developed different parts of an automobile and through the special effect of animation imparted all possible motion to the model. The technology is further enhanced by Kiulera 4, who treated product and process modeling as a kernel for the virtual manufacturing environment. In his work, Kimura has incorporated significant modeling issues like representation, representation language, abstraction, standardization, configuration control, etc. Arangarasau and Gadh 5 contributed towards the virtual prototyping that are constructed using simulation of the planned production process using virtual manufacturing on a platform of MAYA,3D Studio Max and VRML, etc. At .Jadavpur University, research work 6, 7 is being carried out to simulate the gear manufacturing processes using A I Ill)CAD and 31) Studio Max as platforms. Software has been developed that helps the design engineers to understand the problems related to spur gear operation and its manufacturing process. A study of the state of tile art and literature review reveal that the scope of virtual manufacturing is wide open for simulating spur gear generation processes. Computer simulation can be very effectively used for viewing along with aiding subsequent analysis of different complicated manufacturing processes using the concept of design centered virtual manufacturing. With this objective in mind, an attempt is made to virtually manufacture spur and helical gears from the blank using a rack cutter. The scope of the work includes the generation of design data for the spur and helical gears and the rack form cutter, the generation of solid models for the cutter and blank, and finally to simulate gear-manufacturing process through animation. The main motivation of the work is to simplify the task of designing, and to study the gear generation process that can be understood by a layman and to present a realistic view of it. All the processes are developed on the platform of the 3D Studio Max, which is one of the most important virtual tools. The software is developed using max-script, an object contained programming language that can be run in 3D Studio Max environment. 2 Description of the software The max-script language is basically an image processor that creates the visual effects in 3D Studio Max. In addition, it can be used for design calculation and subsequent checking. An attempt is made to develop the entire package in modular form so that any further improvement can be implemented easily without affecting the others. The entire work is carried out in a 3D environment. The modular structure of the entire package is presented in Fig. l. The major modules are: input module, gear design module, virtual manufacturing module and special module. A brief description of these modules is mentioned below. 2.1 Input module This module is developed to provide input parameters that are essential for (tie design and development of the spur and helical gears and the corresponding cutters. In order to make the software user friendly, the process of inputting the data is specifically done through an input dialogue-box created by the max-script-language. A sample dialogue box is shown in Fig.2. Some fields have some restrictions like predefined lower or upper limits or predefined steps for increment or decrement. This is done purposively to make the environment more user friendly and to restrict the user from entering invalid data, for example, a user cannot make the number of gear teeth less than 18. 2.2 Gear-design module Before going for the generation of the gears, one should evaluate the various design parameters of the gears to be manufactured based on the input parameters. In order to design a gear pair, the following data are essential. I Rpm at which the gear is running 2. The power being transmitted 3. The transmission ratio of the assembly In addition, users may specify the following operational conditions/parameters: 1. Precision of the gear assembly 2. Pressure angle of the gear 3. Material of the pinion 4. Type of shock load required for the pinion to take up 5. Helix angle in case of helical gear If the user is not satisfied with the output, he can modify the input to obtain desired output. In this module, the entire design procedure for the gears has been treated. The different aspects of design calculations, for example, dynamic load, static load (fatigue load) and the wear load have been calculated in separate programs, and are displayed through the output dialog box. While designing the gear, it has been kept in mind that the gear has to form mesh with that of the rack, so care has been taken to avoid the interference of the mating pair. 2.2.1 Methodology Varieties of gear cutting processes are available and are generally being followed in the industries during their manufacturing. In this paper, Focus is given on gear manufacturing through generation. The underlying principle of gear design is based on the fact that the profiles of a pair of gear teeth bear a definite relationship to each other such that the pair of teeth have a predetermined relative motion and contact at every instant. Therefore, if the relative motion of the profiles and the form of one of them is known, the determination of the form of the other may be regarded as tile problem capable of solution by either graphical or analytical means. The actual production of gear tooth represents a solution to the above problem by mechanical means known as generation. The generation is a method that follows the following principles. 1. A cutting edge (basically a gear with cutting edges) is given a motion. As a result, it is caused to sweep out the surface corresponding to the actual teeth surfaces of the known member of a pair of conjugate gears. 2. A blank is mounted at an appropriate relationship to the cutter. It is given a motion that the finished gear must have relative to that of the cutter. As a result of the simultaneous movement and the cutting action of the cutter, teeth are formed on the blank conjugate to that represented by the cutter. In fact due to the addition of the relative motion, the profile given to the work piece is different from that of the cutter. This differentiates the generating from the forming operation. 2.2.2 Spur gear Generation of spur gear by means of cutter corresponding in form to the mating gear is well known. Cutter may be in the form of a rack. For an involute system of tooth profiles, the cutter corresponding to the rack will have straight sides. The arrangement of such a cutter relative to the blank is shown in Fig. 3. The cutter is adjusted radially with respect to the axis of the work. It is reciprocated so that its edges may sweep out the surface of the teeth of the imaginary rack forming the basis of the design of the tooth profile of the blank. In addition to this reciprocation, the cutter is advanced in the direction of the pitch line and at the same time the work is rotated about its axis at a speed such that it is pitch point has the same linear veloc ity as that of the rack. In other words, the pitch circle of the blank and the pitch line of the rack roll together. In consequence the straight cuttings edges generate the involute profile in the blank. For such a process to be continuous, The length of the cutter should be somewhat longer than the pitch circumference of the work； since this is usually impracticable The cutter is withdrawn from the work after it has advanced a distance equal to all integral number of pitches and return to its starting point， the blank in the meantime remains stationary This is repeated until all the teeth are cut 2.2.3 Helical gear It is well known that a helical involute gear is conjugate to a straight rack having inclined teeth Therefore， the same method described above can be employed to manufacture a helical gear However, the direction of reciprocation of the rack cutter must be inclined to the axis of the blank at all angle equal to the helix angle of the gear The cutter must roll over the blank in a direction similar to that described earlier The simultaneous motion involved and the orientation of the cutter relative to the blank during the cutting operation is shown in Fig.4 2.3 Virtual manufacturing module This module has been divided into two sub sections： (a) cutter generation， and (b) gear generation 2.3.1 Cutter generation In this section of the virtual manufacturing， a solid model of the rack form cutter is developed. This cutter is used in the later stage to animate the gear generation process in the virtual environment The cutter with all its cutting geometry such as rack and clearance angles have been provided Figure 5 exhibits a 3D solid model view of the cutter developed by the software 2.3.2 Gear generation This module is further subdivided into two parts， namely, (i) spur gear generation module，and (ii) helical gear generation module. (i) Spur gear generation In this sub module, spur gear is generated. In order to simulate the actual machining operation, the blank, which is to be used for the generation of spur gear, is bolted on the movable tabletop. The required washer and back-plate are also tied with the same so that it will have a firm support and be ready for the machining purpose. The cutter is positioned at a desired location. Afterwards, the cutter is given requisite motion to generate involute profile tooth. Generation by means of such a tool is called copy-generation. The arrangement of such a cutter relative to the blank is illustrated in the Fig, 6. The kinematics of the gear shaping process involve the following motions. 1. Reciprocation of the cutter 2. Tangential feed of the cutter and rolling of the gear blank 3. The advanced and reliving motion of the gear-blank 4. Radial feed of the cutter 5. Indexing of the gear-blank All of the above input parameters can be entered through tile input dialog box. In the software, provision is made to display the following motions of the system in the animation mode so that the users have the feeling of a virtual environment created in 3D. (ii) Helical gear generation In the case of helical gears, as the cutter reciprocates up and down over the gear blank. It makes a definite angle with the vertical, equal to the helix angle of the cutter (Fig. 7). As a result, a few teeth that are inclined to the axis of the blank will be partially generated on the gear blank at one time. None of the teeth will be complete in first phase following the principle of gear generation . 2.4 Special module One of the major objectives of the software is to simulate the various simultaneous movements involved in a gear generation process. In the special module, additional features are provided for better understanding of the gear generation process. They are (a) camera views (snap shot), (b) camera views (animated), and (c) movie files. 2.4.1 Camera views (snap shot) The software provides the facility to place the camera at different coordinate positions and thus display different camera views of the cutting process. These are the still pictures taken in render form at successive intervals of the machining process. Still pictures of the partially cut pinion along with that of the cutter at every step of cutting is recorded and enable the user to feel the reality in a virtual environment, 2.4.2 Animation and movie Animation is the backbone of virtual manufacturing as it gives life to already created stationary objects, in other words, it simulates the dynamic behavior of different components. In order to create the effect of animation, a series of still pictures are first generated with a little change of position of the objects from the previous one. When these pictures are displayed in proper sequence at successive interval, they create the impression of moving objects. Each of these pictures is known as flame. For the animation, time interval between successive frames is very important. Generally, the human eye can perceive a frame rate between 60 frames per sec (fps) and I0 fps. The illusion of continuous motion as opposed to a fast paced slide show starts to break down under 1 2 fps. So, frame rate is to be kept above this limit. Generally the frame rate for films becomes standardized at 24 fps. In addition, the animator has to decide whether a given motion has to be shot on ones or on twos. For simple motion it is better to shoot on twos in which case each frames would be shot tw ice, making the effective playback rate 12 fps. For a very swift or intricate motion, the frames of shooting on ones are generally recommended to keep continuity. The cutter and the gear blank occupy different positions in each of the frames depending on the kinematics relationship of the cutting process. This is achieved through the max-script programming environment of 3D Studio Max. They are stored in the hard disk as rendered views of the objects so that whenever necessary they can be run efficiently with the help of Windows media player: 2.4.3 Animated camera view The software has the additional facility to pan the camera as the gear generation process is in progress. The procedure is quite simple and is described below in brief. As mentioned in the earlier section, a first snap shot of the machining process is taken with the camera situated at a particular position. The next frame is taken with the camera position shifted a little bit from its original location. This process continues until the camera comes to the pre-determined end position. The number of frames to be created within the interval is decided as per the visual requirement. Each of the frames captures the progressive development of the cutting process, while the camera moves along definite path. When these frames are projected on the screen successively, it creates the effect of panning the camera. This facility is very useful to understand the complex mechanism of the gear generation process. However, setting of camera locations requires a thorough understanding of 3D co-ordinate systems. 3 Results and discussions It is not possible to present all the feature of the software. Some of the salient features are highlighted below. As the cutter reciprocates up and down over the gear blank, a few teeth will be partially generated on the gear blank at a time. None of the teeth will be in complete shape in the first cut following the principle of gear generation. It should be noted that the cutter teeth profile is straight edge whereas, in the case of gear, it has an involute profile. In order to create the impression of cutting, a large number of frames are generated, each one exhibiting a different amount of material removal from the gear blank. The downw ard motion of the cutter is assumed to be the cutting stroke. The requisite depth of cut is introduced by bringing the cutter to the predetermined position above the blank. The gear blank below the cutter is not yet cut. This is one frame and is shown to the viewer. The next frame shows the sequence when the cutter just finishes the cutting motion and a few partial teeth are developed on the blank. The successive frames illustrate the withdrawal of the cutter, its backward movement, indexing of the gear blank, and positioning of the cutter for the next cutting action. When all these frames are shown one after another, the observer will have the impression of virtual manufacturing of the gear. This process continues until all the teeth successively pass on the pitch circumference of the gear-blank. Figures 8, 9 show a few of the frames during the cutting process of spur and helical gears, respectively. The software has the facility of creating movie files in which a user can control projection of frame rates. Therefore, it is very useful for demonstration purpose as well. The user can change the camera view as per his requirement for better understanding of the operational principal. 4 Conclusion A user-friendly software package has been developed that can tackle the problem of gear design and subsequent visualization of the gear generation process in a virtual environment. It also focuses the development of a rack form cutter, which in the later stage is used for the generation of the gear. All the models are developed in a 3D environment. Additional features like camera views, movie files, etc. are incorporated for better understanding of a fairly difficult subject. Provisions are made to enter the input data through dialog box. If there is incorrect data, a warning message is given by the software indicating what step to be followed next. The results of all the design calculation are indicated in the output dialog box. For a designer these values are very useful information. Using the above output, a designer may have an overall idea about the gear to be manufactured. Once the designer is sure about the output results of the design calculation, he can proceed forward for subsequent virtual manufacturing operations. He can also switch between design module and manufacture module at will, thus leading to an optimized product. References 1. 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Delhi, Delhi, 18 19 December, pp 683 688 译文： 虚拟制造在齿轮生产中的应用 摘要 齿轮的制造过程相当的复杂，这归结于各种各样的刀具和工件同时运动的出现。 在本文，为了使直齿圆柱齿轮、斜齿圆柱齿轮以及相应机架形式的车刀成为制造的必需品而产生了有意义的设计数据。 使用这个信息，刀具和毛胚的实体模 型开始发展，并且最后齿轮制造过程应用于虚拟制造环境当中。 用户有权在设计和制造方式之间任意选择。 这个综合过程也有利于开发一个优化产品。 为了对操作原则有更好的理解，动画设施以电影的形式也包含于其中。 关键词 虚拟制造 动画 齿轮滚铣法 1 介绍 在机械制造应用中，齿轮是非常常见的机械零件。然而 , 齿轮制造似乎相当的复杂，甚至对于那些在相关领域有广泛技术知识的人也是如此。常规齿轮滚铣生成过程如铸造、塑造、滚铣等，通常是在二维草图里表示。有些零件可能是由二维模型途径所不能充分描述的。在齿轮滚铣生成情况下，借 助于二维模型可能很难了解复杂的几何形状和制造过程。如果你改为使用 3D 实体模型，这些限制可能会部分地被克服并且更有助于理解。但是 ,除非你使用动画代替齿轮轮胚和刀具的运动，否则使用三维实体模型可能并不总是保证复杂齿轮滚铣生成过程的清晰。在虚拟制造技术的帮助下，这可能非常有效地达到。这种技术是在电脑屏幕上去模仿实际世界而创建的一个虚拟环境。在虚拟环境里获得信息库和专门技术，这使用户更加有意义地应用于现实生活中。 在不同的领域中，虚拟制造被许多文章提到，一些最新并且重要的文章如下：Tesic 和 Baneljee 曾经 致力于快速原型法，这种方法对于设计、可视化、检验是一项新技术。图形用户界面、虚拟现实技术、蒸馏、偏析和自动分析是他们工作的重要对象。 Balyliss et al 处理了模型发展在虚拟环境里使用三维可视化对象的虚拟现实技术 。 1994 年， Balyliss et al 发表了使用 VM 工具设计的实体模型技术理论，如 VRML（虚拟现实制造语言）和 3D Studio Max。他们开发了汽车的不同零件，并且通过动画的特殊效果对模型给予所有可能的运动。这项技术有Kiulera 进一步提高，他把产品模型和过程视为虚拟制造环境的核心 。在他的工作中， Kimura 合并了主要模型的表示法、表示法语言、抽象、标准化、结构控制等等。在 MAYA 平台， 3DStudio Max 和 VRML 等等上面， Arangarasau 和 Gadh致力于虚拟原型，它是对使用虚拟制造的计划生产过程的模拟。在 Jadavpur 大学，研究工作是使用 AUTOCAD 和 3D Studio Max 作为平台去模拟齿轮制造过程完成的。帮助设计师了解关于直齿圆柱齿轮的运动问题和它的制造过程的软件已经开发了。 对文献资料的调查情形表明虚拟制造的范围扩大是为了模仿直齿圆柱齿轮的生成过程。计算机模 拟为了观看变得身份有效，并使用了虚拟制造的集中设计，这有助于不同制造过程的随后分析。有了这个目标，就企图在毛胚上面使用齿条刀具虚拟制造直齿圆柱齿轮和斜齿圆柱齿轮。工作的范围包括直齿和斜齿以及机架形式车刀的设计数据的产生，车刀和毛胚实体模型的产生，以及最后通过动画模拟齿轮的制造过程。 工作的主要目的是简化设计任务和齿轮虚拟制造过程的研究，这样可以是一个外行人所理解，并表现出它的现实意义。所有的过程都是基于 3D Studio Max平台开发的，它是一个非常重要的模拟工具。软件的发展使用最大的脚本，这个对象包括可 以在 3D Studio Max 环境中运行的语法语言。 2 软件的描述 最大的脚本语言基本上是在 3D Studio Max 上面创建一个视觉效应的图像处理机。另外，它可以为设计演算和随后检查所使用。以模块形式开发整个部件，以便使任何的改善在不影响其他部件的情况下都能容易的贯彻。整个工作都是在3D 环境下实现的。整个部件的模块结构在表现如图 1，主要模块是：输入模块、齿轮设计模块、虚拟制造模块和特殊模块。这些模块的一个简要说明叙述如下。 2.1 输入模块 这个模块的发展是提供输入参数，这些参数是设计和发展直齿、斜齿和 相应刀具的基础。为了是软件用户更亲和，输入参数的过程是通过由最大脚本语言创建的输入对话框完成的。例如在图 2 中所表示的对话框。一些领域有一定的限制，如：预定义的上下限、增量或减量步骤的预定义。这样有目的的做法是环境更加的亲和，并且阻止用户输入不合法的数据，例如：用户不能输入齿数少于 18 的齿轮。 2.2 齿轮设计模块 在生成齿轮之前，基于输入参数，你应该评估制造齿轮的各种各样的设计参数。为了设计成对齿轮，以下参数是重要的： 1. 齿轮运行每分钟的转数。 2. 力的转换。 3. 装配的传动比。 此外，用户也可以指定以下操作的 情况 /参数： 1. 齿轮的装配精度。 2. 齿轮的压力角。 3. 小齿轮的材料。 4. 小齿轮所能承受的冲击载荷的类型。 5. 斜齿轮的螺旋角。 如果用户对输出结果不满意，他可以修改输入参数以获得理想的输出结果。在这个模型中，齿轮的整个设计步骤是固定好的。设计计算的不同方面，如动载荷、静载荷（疲劳载荷）和欠载荷在不同程序里已经计算好了，通过输出对话框展示出来。当设计齿轮时，你必须知道齿轮和机架的啮合情况，这样就可以避免一对齿轮啮合的干涉。 2.2.1 方法论 在工厂的加工过程中，各种各样的切齿过程是有用的，并且通常被从事。在本文中， 重点是通过“生成”来说明齿轮的制造。 齿轮设计的根本原则是基于一定的事实，那就是一对齿轮的齿廓具有一定的关系，如：一对轮齿有预定好的相对运动和每一瞬间的接触情况。因此，如果齿廓的相对运动和其中一个的运动形式是已知的，那么另外一个所定义的形式就可以被认为是通过绘画或分析的手段可以解决的问题。齿轮轮廓的实际生成是通过机械方法表示了解决上面问题的一种方法，就是大家所知道的“生成”。生成是根据以下原则的一种方法。 1. 一个切削刃给定一个运动（基本上每个齿轮都有切削刃）。因此，这就是计算一对共轭齿轮已知部分的表面所对应的 实际齿廓表面的原因。 2. 一个“毛胚”装配在一个相对于刀具的合适位置，精加工的齿轮必须相对于刀具有一个给定的运动。作为同时运动和刀具切齿运动的结果，轮齿是在相对于刀具变化的毛胚上形成的。 实际上由于相对运动，工件的给定轮廓是不同于刀具的。这种“生成”不同于“成形”操作。 2.2.2 直齿圆柱齿轮 直齿圆柱齿轮的生成是依靠刀具相对于啮合齿轮的形式，刀具可能是齿条的形式。因为一个齿廓的渐开线规律，就是刀具相对于齿条有直的边。 这样的刀具相对于毛胚的排列如图 3 所示。刀具相对于工件的轴线做径向调整，这种往复运动以至于 它的刀刃可能破坏虚拟齿条的表面，虚拟齿条是根据毛胚齿廓设计的。除了这种往复运动，刀具在节线方向上，并且同时工件以一定的速度相对于轴转动，以至于作为齿条的每个节点都具有一定的线速度。换句话说，毛胚的节圆和齿条的节线重合，因此直的切削刃在毛胚上面形成了渐开线齿形。 这样来说，刀具应该比工件的节圆长点。因为这样是不可能的，所以刀具在前进了等于整个节距的距离并返回起始点之后开始远离工件，同时毛胚是固定的，这个运动不断重复直到所有的轮齿加工完。 2.2.3 斜齿圆柱齿轮 总所周知，斜齿渐开线齿轮有与其共轭的齿条倾斜的 轮齿，因此，采用上面描述的方法同样可以制造一个斜齿圆柱齿轮。然而，齿条刀具的往返方向必须倾斜与毛胚的轴线，这个角度等于齿轮的螺旋角。刀具的转向必须与上面描述的方向一致。与同时动作有关的以及在加工操作时相对于毛胚的刀具方向表四如图4 所示。 2.3 虚拟制造模块 这个模块可以分为 2 个部分：（ a）刀具的生成，（ b）齿轮的生成 2.3.1 刀具的生成 在虚拟制造的这一部分，一个齿条刀具的实体模型正在发展。在虚拟环境中，这个刀具是在后面的步骤中用来模拟动画齿轮的生成过程。刀具和它所有的几何学，例如刀架和后角，图 5 表 示的就是通过软件制作的 3D 实体模型。 2.3.2 齿轮的生成过程 这个模块被细分为 2 部分 （ ）直齿圆柱齿轮滚铣生成模型（ ）斜齿圆柱齿轮滚铣生成模型 （ ）直齿圆柱齿轮滚铣生成模型 在这个小模块里，生成的是直齿。为了模拟实际的机器操作，用来生成直齿圆柱齿轮的毛胚锁定在可移动的桌面上。必须的垫片和支承板都约束在一起，这样不但可以使它有牢靠的支承，而且还为了加工的需要。刀具放置在一个重要位置，然后给予刀具必备的运动去产生渐开线齿廓，这样的生成是依靠一个仿形生成工具，与毛胚相关的刀具排列如图 6 所示。 齿轮成 形过程的运动学包括一下运动： 1. 刀具的往复运动。 2. 刀具的切向进给运动和齿