在现场为优化模具制造工艺铣削仿真外文文献翻译、中英文翻译

附录 1：外文翻译在现场为优化模具制造工艺铣削仿真K. Weinert (2). A. Enselmann, J. Friedhoff 多特蒙德大学，加工技术部，多特蒙德，德国1997 1 月 9 日收到摘要当铣复杂曲面的主要 问题是有限的精度时，是由于铣削刀具变形引起切削力和过程的可靠性欠佳引起的。为提高表面质量，和保持高的过程可靠性，方法之一是基于计算机的参与分析和进给速率适应。而适应进给率的目的是为了使他们发生复杂曲面半精加工，以避免难以忍受的高刀具载荷。使用高效的开发方法，用体积模型来仿真切割过程。而最佳的进给率的计算需要从 3 轴铣削的主要技术方面进行考虑。发达国家提高效率的做法就是一个被证明了的实际例子。关键词：工艺优化，铣削仿真，复杂曲面1 引言成形刀的使用是作为一个广泛的生产技术的必须刀具，例如注塑或模锻。使用强大的 CAD / CAM 系统来作为描述和制造的几何形状表面的成形工具，是完成从设计到制造的最快途径。和侵蚀性技术相比较，制造这种模具的最经济的方式是直接进行铣削加工。经济铣削过程中最重要的先决条件之一是有良好的切削条件。优化铣削功能强大的 CAM 系统所提供的发展是带来显著的刀具寿命，表面质量和经济的加工方面的改善。关于精密加工存在的主要问题：l 由于不同的约定条件，尤其是在半精加工和过程的可靠性差。l 由于切削力切削刀具变形引起的轮廓偏差。出现这些问题，尤其是当使用薄铣刀时。而改善轮廓的质量和工艺可靠性的主要理论方法是：l 适应进给率，使用接触条件的分析.l 轮廓偏差以计算机为基础的轮廓偏差预测和补偿的赔偿有几篇论文，在研讨精度，工艺可靠性和铣削过程所需的时间时，可显著改善切削过程中使用不同的模型来确定切削条件。关键的方面是，所有被称为切削条件的型号。为了 2的三维问题，参与条件被数控路径本身所确定形成，而且是在很宽的范围的。铣复杂曲面时，几乎完全在模具制造业发生，参与条件不断以非常快的速度变化和数控路径来计算这些值一般是不可能的。图 1 轮廓偏差测量与优化策略铣床在本文中，讲述的是铣削过程的模拟方法。此模拟计算对任何特定时间的实际加工零件的几何形状的数控路径进行控制，使人们有可能以验证自动生成数控路径。但是，尤其是，它允许在复杂曲面铣削过程的参与条件下进行必要的值计算。仿真是基于离散量模型和方法，降低了计算机模拟过程需要的时间和内存空间，文献一直作为被忽视的一个方面甚至到现在为止。以下各节描述的轮廓偏差的主要来源，是为适应这种高效的仿真模型为基础的进给率优化铣复杂曲面的方法。2 轮廓偏差的原因现在将讨论铣复杂曲面的一个典型的例子。图 1 所示的工件显示一个典型的几何，通常发生在模具的表面区域。现进行优化铣削路径策略。高倾角值和相对平坦的地区的螺旋铣削领域的圆周铣削表面的精加工。图 2 参与的条件分析使用这些优化的铣削策略，正常回火钢制成的工件被铣削，其中有一个 1600 逻辑模块和模具使用，总轮廓测量的结果显示，平均面积为 0.02 毫米的偏差。而最大偏差，发生在中空成型，达到 0.04 毫米。从这里描述的例子得出的结论，HSC 铣削优化的铣削策略可应用于大部分地区使用的工具，而有长度的且比例不超过 5 ，以获得令人满意的结果。另一方面，如果等高品质更高的要求，尤其是当使用长，最终沉模轻工具，加工的结果并不令人满意。轮廓变形的主要原因是：l 铣削路径偏差，是由于有限的动态的数控机 CA-数控机.l 切削力切削工具，工件和机器的变形。第一个问题提到的 - 由于路径的偏差。是由于机器的有限动态能力 - 可避免使用特殊的控制算法，像前瞻和后仰。轮廓偏差也可能出现由于对切削刀具的变形，工件和机器。而最大的偏差是由刀具的刚度相对较低，尤其是在精铣时，刀具具有高的长度与直径之比。在这方面的另一个问题是不理想，而半精加工过程的可靠性。由于约定条件的变化，刀具负载不是在一个恒定的水平。3 进给速率适应算法一个合适的方法是降低轮廓偏差，同时保持高度工艺可靠性的基础上，分析当前的约定条件的细节。以下各节详细描述了该算法的发展。3.1 预测的约定条件轮廓偏差预测中的第一和最重要的一步是分析的接触条件。这种分析是必须的， 以确定确切的切割芯片体积和之后所产生的横截面为 1 函数的芯片面积。对于这个问题的一个可行的办法是对零件表面的几何表示在任何给定的时间内有一个坚实的建模系统反复的布尔运算。这种方法的缺点是执行这项任务所需的计算数量庞大。因此，它不适合使用这种方法在实践中，因为内部计算的金额将增加在反复应用布尔运算。模拟 3 轴铣削的一般问题可以描述如下：设 W 是在三维空间中的线段集定义一个给定的刀具参考点的路径。此外，让 f 是一个函数，代表刀具。此外，让 f 是一个函数，代表刀具。 f 映射一个二维的坐标系统为负实数的起源左右对称的地区。典型的例子是平面铣刀，球头铣刀，实数 r 代表刀具的大小。在这两种情况下的入刀点是用来作为参考点。目的是为了计算削减到坚实的物质表面 时，刀具的参考点沿路径移动，在 M. 首先，我们假设原料块是在一个合适的坐标系平行管道与坐标 x 反函数 r 多尺度自回归 ， y最小， z 最小和 z 回应矩形。表面可描述为刀具表面上所有点的最低沿路径的每一个位置的刀具，它有除了被截断点所在的地方以外的材料块。F（ X，Y）的精确计算是费时，复杂的，由于复杂的数值不稳定，造成详细几何所产生的表面。一个确切的做法已由川岛5实现，并由惠4开发出这个问题的离散解决方案。背后的分立解决方案的初步设想已描述了若干修改在9,11,12前，惠4 使用这个简单的解决办法，提高使用计算机图形应用程序开发的算法，像扫描转换， 音量分析以避免计算刀具扫地出门。我们已经制定的，与计算机科学系在一起的解决方案，多特蒙德大学，惠4和作者12所使用的方法是一个类似离散的方法。他们采用一个固定的采样平面来计算高度场，即从材料块的上面。和12相反，我们的重点在于减少抽样方法的缺点，也就是已知的简单实现计算机需要相当长的时间和内存空间。这一事实已被忽略，直到现在为止。8中所建议的解决方案的细节描述。图 3 给出了一个例子。工件表面粗铣（ 4200 路径，第 18 号第一个奔腾 PC 上的计算时间。数控路径模拟为 60 兆赫）。图 3 计算所产生表面呈现的图像图 4 截面积和进给率的关系由粗铣数控路径铣削仿真计算显示渲染图像。计算所需的时间计算为 4200 而英特尔电脑计算数控路径这一结果是 18 秒。3.2 适应进给速率的基本方法图 4 中的主要思想是描绘进给速率适配。计算是基于截面积的自动加工中心剪切，从接触条件的分析得出，如上所述。为进给速率适应这一因素被修改两个修正因子，从而为了考虑到切割和倾斜路径的对称性技术的影响。使用的因素是真正的切截面积，无形中增加或减少。稍后将讨论的因素和公式，用来计算校正因子。修改后的截面积计算公式：如果计算截面积模拟通带调制器低于指定值最大的进给率。如果模拟通带调制器所在的最高和最低值（最小 Amod 和最大 Amod）之间，实际进给率直线下降：如果修改后的值，Amod 比 Amodmax 高，则进给率不会进一步降低，也就是说， 它保持尽可能低的水平通过 vfmin 定义。如果发生这种情况，产生一条警告消息，说明事实，说明切割的最大截面面积已超过事实。3.3 对称的参与两个修正因子的定义是要考虑对称性和路径倾斜的切割技术的影响。第一校正因子温度 DGES 框 工程样板的对称性参与的影响（图 5） 。首先对称因素 FVM 计算，左侧（进给方向看）和右侧之间的交叉切截面积的比例确定。他的因子描述的参与情况：无论是在刀尖或只在刀具的圆周对称的参与。对称因子定义为：图 5 校正因子参与对称性的定义在一个完全对称的参与的情况下的因素是设置为 1 （图 1） 。对于因素不断增加的最大的，我尝试介于 1 和可定义的最低值 fsym，最小的值：这种现象的原因是，在与对称的接触在刀尖面积的比较,刀具的圆周参与导致更高的刀具挠度。3.4 铣床方向的影响它是一个技术的事实，明显高于向上指示的路径的情况下，向下指示的切割路径的工具负荷（暴跌切割）是较高的。考虑到一个路径倾向的校正因子定义如下（图6）：在水平对齐的路径的情况下修正系数设置为 1 ，即有不改正。向下对齐的路径， 无形中增加了计算的切截面积，向上指示的路径减小。3.5 加工动力学方面考虑到机器的动态能力（图 7）的进给率计算，实现在适当的位置这是必要的。在这种情况下，必须进行减速的长度计算和新的进给率值必须添加到数控文件在正确的位置。减速的长度被定义为：图 6 定义路径倾斜的校正因子49图 7 减速长度计算用 am，等于最大的减速机。在此表达的第一项是真正的减速造成的动态能力有限的机器和值 D （刀具直径）长度作为一个安全参数。它是用来确保在削减量超过给定值前计算出最佳的进给率。4 算法的应用为了表明发达的铣削进给率的模拟和优化的能力，一个典型几何的一部分已被粉碎。加工的第一步是由 8 毫米直径的球头立铣刀粗铣，使用口袋铣削循环。下一步是使用直径 6 毫米的球头立铣刀进行半精加工铣削。这个加工阶段的路径是走直线的形状。一个问题，往往产生在半精加工这部分，是过程的可靠性低，致使工具损害。铣削切削力这部分记录。在图 8 中，在狭窄的领域的一部分区域可以看出，即一个地区， 仍然主要是机加工的 8 毫米的刀，导致高刀具载荷的影响 6 毫米刀（顶部） 。进行比较，优化进给率（底部）铣时，切削力记录。图 8 显示了相应的力量在 z 方向。约定适应的结果是相对稳定的工具载荷，它在稳定的切削条件下没有高力峰产生和一个令人满意的过程中的可靠性。5 小结铣复杂曲面的主要问题是由于长，薄的铣刀和过程的可靠性欠佳的有限刚度的轮廓偏差。一个雕刻的 3 轴铣削仿真使用适当的方法，同时实现了高的工艺可靠性，减少轮廓偏差。他算法的开发是基于一个高效，离散模型分析参与条件允许的容积计算在给定的时间，以便进给率进行优化，以确保恒定的刀具载荷的切削条件。通过运用这种方法显着改善，准确性和过程的稳定性方面，可以实现铣复杂形，复杂曲面。6 参考图 8 比较传统铣削切割部队（顶部） 和铣削进给速率适应（ 底部）1 Altintas, Y.，1996 年，一般的螺旋立铣刀的力学和动力学模型，在机械工程研究所纪事， 431 :59 -642 Armarego, E.J.A, Wang. J., et. at., 在 1995 年，计算机辅助面铣刀力量允许对牙齿的运行，机械工程研究所 4411 :43- 48 年鉴预测切削模型3 Bieker, R.,1991 年钢模具，数控铣床。 VD-V 出版社，杜塞尔多夫4 Hui, K.C., 1994 年，在图像数控仿真空间应用的固体清扫。计算机视觉， 10:306-3165 Kawashima, Y., Itoh, K. et. al., 1991 年，数控加工核查灵活使用空间划分为基础的实体模型的定量分析方法，计算机视觉， 7:149-1576 Spiewak, S. 1995. 铣切屑厚度的改进模型。史册的“机械工程研究所。4411:39-427 Weinert, K., Enselmann. A., 1995 年。数控功能为 HSC 铣削领域的工具和模具制造，柔性自动化和智能制造（ FAIM ） ，begell 楼公司，纽约， 957-967附录2：外文原文Milling Simulation for Process Optimization in the Field of Die and Mould ManufacturingK. Weinert (2). A. Enselmann, J. FriedhoffUniversity of Dortmund, Department of Machining Technology, Dortmund, Germany Received on January 9. 1997AbstractWhen milling sculptured surfaces the majorproblems are the limited precision due to milling-cutter deflections caused by the cutting force and a unsatisfactory process reliability. One method for improving surface quality while maintaining high process reliability is the computer-based engagement analysis and feed-rate adaptation. The aim of the feed-rate adaptation is to avoid intolerably high tool loads as they occur while semifinishing sculptured surfaces. The method developed uses an efficient, volume model to simulate the cutting process. The calculation of the optimal feed-rate takes the main technological aspects of3- axis milling into account. The efficiency of the approach developed is demonstrated with a practical example.Keywords: Process Optimisation, Milling Simulation, Sculptured Surfaces1 IntroductionThe use of form tools is necessary for a wide range of production technologies, for example injection-moulding or drop-forging. The fastest way from design to manufacturing can be accomplished using powerful CAD/CAM-systems to describe and manufacture the surface geometry of the form-tools. The most economical way to manufacture such moulds is the direct milling process, in comparison with erosive technologies. One of the most important prerequisites for an economical milling process is to have favourable cutting conditions 3.The development of optimised milling functions offered by powerful CAM-systems leads to significant improvements with regard to tool-life, surface quality and economical machining. Two major problems regarding precision machining exist:l Poor process reliability due to varying engagement conditions especially while semi-finishing andl contour deviations caused by cutting-tool deformations due to cutting forces.These problems arise especially when thin milling tools are used. The main theoretical ways of improving contour quality and process reliability are:l Feed-rate adaptation using an analysis of engagement conditions 12 andl contour-deviation compensation by computer-based contour-deviation prediction and compensation 7.Several papers have shown, that accuracy, process reliability and the time required for the milling process can be improved significantly when using different models of the cutting process to determine the cutting conditions l, 7, 121. The crucial aspect is that for all models the cutting conditions have to be known. For 2 and 2 % dimensional problems, the engagement conditions can be determined form the NC paths themselves and are constant over a wide range. When milling sculptured surfaces, which occur almost exclusively in the die and mould manufacturing industry, the engagement conditions constantly vary at a very quick rate and in general it is impossible to calculate these values from the NC paths.Fig. 1 Contour deviations measured when milling with optimised strategiesIn this paper, a method for simulation of the milling process is presented. This simulation calculates the actual geometry of the machined part at any given time during the processing of the NC paths and makes it possible to verify the automatically generated NC paths. But especially, it allows the calculation of the necessary values of the engagement conditions during the milling process of sculptured surfaces. The simulation is based on a discrete volume model and our method diminishes the time and memory space the computer requires for the simulation process, an aspect which has been neglected in the literature up to now. The following sections describe the main sources of contour deviations and a method for optimising the milling of sculptured surfaces by an adaptation of feed-rates based on this efficient simulation model.2 Causes of contour deviationsA typical example of the milling of sculptured surfaces will now be discussed. The workpiece depicted in figure 1 displays a typical geometry with surface regions that commonly occur in moulds and dies. The milling was done by optimised milling path strategies. The finishing of the surfaces was performed by circumferential milling of areas with high inclination values and helicoidal milling of relatively flat areas.Fig. 2 Analysis of engagement conditionsUsing these optimised milling strategies, the workpiece made of normal tempered steel which has a final strength of 1600 Nlmm2 and is used for moulds, was milled directly.The results of the total contour measurement showed a mean area deviation of 0.02 mm. The maximum deviation,which occurred in hollow mouldings, amounted to 0.04 mm.The example described here leads to the conclusion, that the HSC-milling with optimised milling strategies can be applied to most parts using tools having alength-todiameter ratio that does not exceed 5 in order to get satisfactory results. On the other hand, if an even higher contour quality is demanded, especially when using long, thin tools for the final die-sinking, the machining results are not satisfactory.The main causes of contour deformations are:l Milling-path deviations due to the limited dynamic ca pabilities of the NC-machine andl Deformation of cutting tool, workpiece and machine by the cutting forces.The first problem mentioned - path deviations due to. The limited dynamic capabilities of the machine - can be avoided using special control algorithms, like look-ahead andfeed-forward.Contour deviations also occur due to deformations of the cutting-tool, the workpiece and the machine. The biggest deviation is caused by the relatively low stiffness of the cutter, especially in the case of finish-milling, by cutters with a high length-to-diameter ratio.Another problem in this area can be an unsatisfactory process reliability while semi-finishing. Due to changing engagement conditions the tool load is not at a constant level.3 Algorithm for feed-rate adaptationA suitable method for decreasing contour deviations while maintaining a high degree of process reliability is the federate adaptation based on an analysis of the current engagement conditions. The following sections describe in detail the algorithm developed.3.1 Prediction of engagement conditionsThe first and most important step in contour-deviation prediction is the analysis of the engagement conditions. This analysis is necessary to determine the exact cutting chip volume and afterwards the resulting cross-sectional area of the chip as a function of thepressure-angle cp for all positions of the NC-data (Fig. 2). The analysis itself is performed by a simulation of the 3-axis milling process.A possible solution for this problem is the geometric representation of the surface of the part at any given time by repeated Boolean operations in a solid modeling system. The disadvantage of this method is the enormous number of calculations needed to perform this task. Therefore, it is not suitable to use this method in practice because the amount of internal calculations will increase during repeated application of Boolean operations.The general problem of simulation 3 axis milling can be described as follows: Let .W be a set of line segments in 3d space defining the path of the reference point of a given cutter.Furthermore, let f be a function that represents the cutter. f maps a symmetric region around the origin of a 2d coordinate system into negative real numbers. Typical examples areflat-end cutters,and ball-end cutters,The real number r represents the size of the cutter. In both cases the origin is used as the reference point. The aim is to calculate the surface which is cut into the solid material when the reference point of the cutter is moved along the paths in M. First we assume the block of raw material to be a parallel piped rectangle with coordinates xminv .rmar, ymins yma, zmin and zmwr in a suitable coordinate system. The surface can be described as the minimum of all points on the cutter surface at every location of the cutter along the path, which in addition have to be clipped where the points lie outside of the block of material.The exact calculation of F(x. y) is time consuming, complicated and numerically unstable due to the complex, detailed geometry of the resulting surface. An exact approach has been implemented by Kawashima 5. Hui 4 has developed a discrete solution of this problem. The initial idea behind the discrete solution has been described in several modifications before 9, ll, 121. Hui 4 improves on this straightforward solution by using algorithms developed for computer graphics application, like scan conversion, to avoid analytic calculations of the volume swept out by the cutter.The solution we have developed, together with the Department of Computer Science, University of Dortmund, is a discrete approach similar to the methods used by Hui 4 and Yazar 12. Like Yazar 12, we calculate the height field with respect to a fixed sampling plane when looking at the block of material from the top. In contrast to 12, our emphasis lies on diminishing the disadvantages of the sampling approach, i.e. the considerable time and memory space required by the computer for known straightfoward implementations. This fact has been neglected in the literature up to now. The details of the proposed solution are described in 8. An example is given in figure 3. The resulting surface of the workpiece by the simulation of the NC paths for rough milling (4200 paths, 18 s computing time on a Pentium PC. 60 MHz.Fig. 3 Rendered image of the resulting surface calculatedFig. 4 Relation between cross-sectional area and feed-rateas calculated by the milling simulation of the NC paths for rough milling is displayed as a rendered image. The computing time necessary to calculate this result for 4200 NC paths is 18 seconds on a Pentium PC.3.2 Basic method of feed-rate adaptationIn figure 4 the main idea of the feed-rate adaptation is depicted. The calculations are based on the crosssectional area of cut Ach, derived from the analysis of engagement conditions, described above. For feed-rate adaptation this factor is modified by twocorrection factors, in order to take into account the technological influences of symmetry of cut and inclination of path. The factors are used to virtually increase or decrease the real crosssectional area of cut. The factors and the formulas used to calculate the correction factors are discussed later. The modified cross-sectional area is calculated by the formula:If the calculated cross-sectional area Amod is below a specified value the maximum feed-rate is used. If Amod lies between the maximum and minimum values (.4mod,min and Am,d,mm), the actual feed-rate is decreased linearly:If the modified value Amod is higher than Amod,max. The feed-rate will not be further reduced, i.e. it remains on the lowest possible level defined by vjm,. If this occurs, a warning message is generated, indicating the fact that the maximum cross-sectional area of cut has been exceeded.3.3 Symmetry of engagementTo take the technological influences of cutting symmetry and path inclination into account two correction factors are defined. The first correction factor C dGescribes the influence of symmetry of engagement (Figure 5). First a symmetry factor f v m is calculated, defining the ratio between cross sectional area of cut on the left side (viewed infeed-direction) and on the right side. This factor describes the engagement situation: whether it is a symmetrical engagement at the tool tip or only at the circumference of the cutter. The symmetry factor is defined as:Fig. 5 Definition of correction factor for symmetry of engagementIn case of a completely symmetrical engagement the factor dceo is set at 1 (figure 1).The factor is increased continuously to the maximum G G for, symme, try values between 1 and a definable minimum value fsym,min:The reason for this behaviour is that an engagement only at the circumference of the cutter leads to higher cutter deflections in comparison with a symmetrical engagement in the area of the tool tip.3.4 Influence of milling directionIt is a technological fact, that the tool load for downward directed cutting paths (plunge cutting) is remarkably higher than in the case of an upward directed path. To take this into account a correction factor for the path inclinationis defined as follows (figure 6):In the case of a horizontally aligned path the correction factor is set to 1, i.e. there is no correction. Downward aligned paths virtually increase the calculated crosssectional area of cut and upward directed paths decrease it.3.5 Aspects of machining dynamicsIn order to achieve the ca