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题名: 复杂型腔数控铣削加工路径规划策略及应用研究
其他题名: Complex Pocket NC Milling Tool-path Planning Strategy and Application Study
作者: 张鸣
导师: 刘伟军
分类号: TG506.6
关键词: 型腔 ; 数控加工 ; 轨迹规划 ; 轨迹连接 ; 高速加工 ; 环切轨迹
索取号: TG506.6/Z33/2011
学位专业: 机械电子工程
学位类别: 博士
答辩日期: 2011-04-15
授予单位: 中国科学院沈阳自动化研究所
学位授予地点: 中国科学院沈阳自动化研究所
作者部门: 装备制造技术研究室
中文摘要: 模具加工是机械加工中的常见问题,目前,随着模型表示方法的成熟和CAD技术在模具设计中的广泛应用,模具中出现了大量的自由曲面,客户对模具加工精度的要求也越来越苛刻,有些模具甚至达到了“纳米级加工”的要求。传统的仿形加工已难以满足客户对精度和效率的要求,数控加工已逐渐成为模具加工的主流。但在应用和普及的过程中,其中的一些深层次的问题体现了出来,突出表现在现有轨迹规划方法与机床加工特性之间的矛盾,现有的轨迹规划方法不能充分发掘数控机床在精度和效率上的潜力。一般而言,模具属于型腔类零件,因此,本文将围绕型腔数控加工轨迹规划中的一些深层次问题展开论述,着重解决其中的一些关键技术问题,以期对模具数控加工轨迹规划提供技术支持。本文的主要研究内容和贡献如下: 1.为了解决环的偏置问题,本文详细论述了一种新的环偏置方法,该方法采用边偏置边裁剪的方法消除了局部干涉环,并通过全局求交将偏置环分成了多个子环;在获得子环后,该方法通过环的旋向剔除了全局干涉环,从而获得了有效的偏置环。在全局求交的过程中,涉及到大量的线段求交问题,为了提高求交效率,本文采用栅格分治存储的方法缩小了全局求交的范围。同时,为了解决加工区域的识别问题,本文提出了一种基于节点深度的加工区域识别方法,该方法首先通过边界环之间的关系构建了边界环树,并根据节点的深度信息得出了材料去除区域;在获得材料去除区域后,该方法对材料去除区域的内外边界进行了偏置,并采用平面布尔运算裁剪了内外偏置环,从而有效地识别了加工区域。 2.本文详细地论述了一种环切轨迹规划方法。该方法首先采用偏置裁剪法生了轨迹环,并采用区域树的树型数据结构对轨迹环进行了管理。然后对区域树进行了剖分,实现了对轨迹环的编组。在获得编组的轨迹环后,该方法以插入过渡点和虚过渡点的方式完成了轨迹环的连接,形成了子轨迹。在获得子轨迹后,本文提出了两种全局优化连接策略对子轨迹进行了优化连接。 3.当环切轨迹的重叠率较低时,在拐角处会存在刀具无法覆盖的残留区域,为了有效地去除残留区域,本文提出了一种牙状清角轨迹规划方法,该方法首先识别出了轨迹中的尖角,然后匹配出了尖角中的尖角对,尖角对标明了残留区域的位置。在残留区域的位置确定后,对每一个尖角对,以子尖角的尖点作为初始条件,该方法采用边计算边修正的方法逐步生长出整个牙状清角加工轨迹。由于牙状轨迹在端点处存在折返,不适合高速加工,针对这一弱点,本文提出了一种高速清角加工轨迹规划方法,该方法通过对牙状轨迹的端点进行双圆弧插值,从而发展出了G1连续的加工轨迹。 4.本文对型腔五坐标加工轨迹规划问题进行了初步研究,详细论述了等参数法和等残留法轨迹生成方法。并针对传统3D轨迹连接方法的不足,提出了一种简单有效的轨迹Zigzag连接方法。该方法使用轨迹线网来管理生成的3D轨迹。该方法按连接特征点在环上的位置组建了双循环链表,然后根据表中信息连接了轨迹线,从而形成了轨迹线网。在获得轨迹线网后,通过用户指定的端口在轨迹线网中搜索可用路径,从而形成了子轨迹;另外,为了简化子轨迹间的全局连接,采用了一种简单的方法来代替传统的启发式算法。 5.为了解决义齿单冠的数控加工问题,本文提出了一种用于义齿单冠加工的三坐标数控加工轨迹规划方法。该方法应用了型腔三坐标加工轨迹规划的研究成果,在该轨迹规划方法中,轨迹规划过程被分为粗加工轨迹规划和精加工轨迹规划两个主要步骤。粗加采用截平面法生成。精加工轨迹则采用了截平面法和投影法两种方法生成。针对精加工过程中的干涉调整问题,本文提出了一种高效率的干涉调整方法对精加工轨迹中的干涉刀位点进行了调整,消除了局部干涉,从而生成了无干涉的精加工轨迹。
英文摘要: Mold machining is a common problem in mechanical machining, at present, with the mature of model geometric representation and the wide applications of CAD technology in mold design, massive free-form surfaces crop up in mold. At the same time, more and more harsh precision required by customers, and some mold even reach to the "nano-level processing" requirements. The traditional copying machining has been difficult to sever the customer requirements of accuracy and efficiency; CNC machining has become the mainstream way of mold machining. However, during the application and popularization of CNC machining, some deep-seated problems has surfaced, which especially evident in the current tool-path planning methods confilicts with the machining characteristics of CNC tools. The current tool-path planning methods can not fully exploit the precision and efficiency potential of CNC machine tools .Because the mold is a typical pocket parts, this paper will discuss some deep-seated problems in the pocket tool-path planning and focus on solving some key technical problems to provide the technical support for the mold NC machining. The main research contents and contributions are as follows: 1. In order to solve the offset problem of loop, this paper discusses in detail a new loop offsetting method, which eliminates the local interference by trimming edges and separates the offsetting loop to many sub-loops by global intersection. After getting the sub-loops, this method deletes global interference loops via the loop rotary direction to get valid offsetting loops. This method involves a large scale of line intersection calculation during the process of global intersection. In order to increase intersection efficiency; this method uses grid divided storage strategy to narrow the global intersection scope. Meanwhile, this paper proposes a node level based method to solve the problem of machining region identification. At first, this method constructs the boundary loop tree via the loop relationship matrix and gets material cleaning regions according to the node level in the tree. After obtaining material cleaning regions, this method indentifies machining regions effectively by offsetting internal and external loops of material cleaning regions and then trimming them by using the planar Boolean operation. 2. This paper proposes a contour-paralleled tool-path planning method. At first, this method uses offsetting and trimming method to generate loops and manages them by using the regional tree data structure. Then this method splits the regional tree to group tool-path loops. After getting grouped tool-path loops, this method links tool-path loops by inserting corresponding points and virtual corresponding points to a sub-path. After getting sub-paths, this paper proposes two optimized global linking method to optimize global linking. 3. When the overlapping coefficient of a tool-path is low, the tool cannot cover residual regions around tool-path corners. In order to dispose residual regions effectively, this paper proposes a tusk-like corner clean-up planning method. Firstly, this method indentifies corners in the tool-path and then matches corner pairs in corners; the corner pair indicates the location of residual region. After the location of residual region is determined, for each corner pair,we take the vertex of son corner as initial condition, this method gradually grow the entire tusk-like clear-up path by adjusting tool-path while calculating. Because the tusk-like tool-path exist reentry at the endpoints, it is not suitable for high-speed machining. To overcome this weakness, this paper proposes a high-speed clear-up tool-path planning method, which develops G1 continuity tool-path by interpolating bi-arcs between endpoints of the tusk-like tool-path. 4. This paper conductes preliminary study for mold five-axis machining tool-path planning and discusses the iso-parameter and iso-scallop tool-path planning in detail. For the disadvantage of the conventional 3D tool-path linking method, this paper proposes a simple and effective zigzag linking method. This method employs the tool-path line net (TPL-net) to manage 3D tool-paths. This method constructs a double circular linked list via the feature point location on the loop and link the tool-path line to a TPL-net. After we obtaines the TPL-net, this method gets the sub-paths by finding valid routes in the TPL-net. In addition, in order to simplify the global linking between sub-paths, this method uses a simple method to replace the conventional heuristic algorithm. 5. In order to solve the dental CNC machining problem for a single crown. This paper proposes a tool-path planning method for denture 3-axis machining. This method applies the outcome of previous pocket tool-path planning research, in which we divide the tool-path planning roughing and finishing tool-path planning to two major steps. We generate roughing tool-path planning by using iso-planar method, and finishing path by using iso-planar or projection method. For the problem of interference adjustment, this paper presents an efficient intervention adjusting method that adjusts the interference points in the finishing tool-path to eliminate local interference and produce a non-interference finished tool-path.
语种: 中文
产权排序: 1
内容类型: 学位论文
URI标识: http://ir.sia.cn/handle/173321/9295
Appears in Collections:装备制造技术研究室_学位论文

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Recommended Citation:
张鸣.复杂型腔数控铣削加工路径规划策略及应用研究.[博士学位论文].中国科学院沈阳自动化研究所.2011
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