夹紧力的反向增量递减规划方法研究

发布时间：2018-05-15 15:06

本文选题：装夹 + 计算机辅助夹具设计　；参考：《南昌航空大学》2015年硕士论文

【摘要】：在加工过程中,工件的装夹是加工工件的必要前提和首要任务。由于受到切削力、切削扭矩等外载的作用,工件将会产生位置移动或转动,甚至飞出机床产生生产事故。因此,工件的装夹稳定性是保证其加工精度的前提,它直接影响工件的加工质量、产品的生产效率以及其制造成本。此外,随着经济的发展,社会对于产品的生产要求越来越高,必须高速度、高质量地完成产品的生产,因此企业就必须最大程度地缩短产品的生产设计周期。计算机辅助夹具设计可以大大缩短夹具设计的时间,随着计算机技术的飞速发展,计算机辅助夹具设计(Computer Aided Fixture Design,CAFD)已成为国内外制造业研究的热点。然而,夹紧力的自动规划却成为阻碍CAFD系统实用化进程的“瓶颈”之一。因此,本论文主要是根据工件装夹方案的力学模型,利用线性规划技术,构建力的存在性和可行性分析模型及其求解方法,实现夹紧力是否有解、是否合理的判断。通过引入夹紧力可行区间的离散化思想,建立夹紧力反向增量递减规划算法。提出的方法不仅能够适用于形状复杂的工件,而且易于编程实现夹紧力的自动化设计,对提高制造水平具有重要的研究价值与现实意义。本论文的主要内容如下:首先,讲述了本论文的研究目的和意义,分析和总结了计算机辅助夹具设计的研究现状和发展动态,介绍本文的研究方法以及创新点。其次,根据工件在装夹布局方案中的受力状态,建立工件在力的单向性约束条件下的静力平衡方程,构建工件的装夹稳定分析模型;在给定装夹元件、重力、加工力的位置与方向,构建了夹紧力的存在性分析方法;针对夹紧力存在的条件下,已知夹紧力大小,构建了力的可行性分析方法。然后,通过引入夹紧力可行区间的离散化思想,建立夹紧力的反向增量递减规划算法。首先根据力的存在性分析方法,判断装夹方案是否具有合理的夹紧力,若无,设计过程结束;若有,根据力的可行性分析方法判断相邻两个夹紧力的可行状态,若相同,按照相同步长增加形成下一个夹紧力,否则以一半步长减小形成下一个夹紧力。如此反复,直至当前步长的绝对值在给定的阈值范围之内,从而确定夹紧力的临界值或临界区间。最后,总结了本文的工作内容,并对以后的研究发展方向进行了描述。
[Abstract]:In the process of machining, the clamping of the workpiece is the necessary prerequisite and the primary task of machining the workpiece. Due to the external loads such as cutting force and cutting torque, the workpiece will move or rotate, and even fly out of the machine to produce production accident. Therefore, the clamping stability of workpiece is the premise to ensure its machining accuracy, which directly affects the quality of workpiece, the production efficiency of product and the manufacturing cost. In addition, with the development of economy, the society has higher and higher requirements for the production of products, and must complete the production of products with high speed and high quality. Therefore, enterprises must shorten the production and design cycle of products to the greatest extent. Computer-aided fixture design can greatly shorten the time of fixture design. With the rapid development of computer technology, Computer-Aided Fixture Design (CAD) has become a hot spot in domestic and foreign manufacturing industry. However, the automatic planning of clamping force has become one of the bottlenecks in the practical process of CAFD system. Therefore, according to the mechanical model of the clamping scheme of workpiece, this paper constructs the existence and feasibility analysis model of the force and its solution method by using the linear programming technology, realizes whether the clamping force has the solution or not and whether the judgment is reasonable. By introducing the discretization idea of feasible interval of clamping force, an inverse incremental decrement programming algorithm of clamping force is established. The proposed method not only can be applied to complicated workpieces, but also can be programmed to realize the automatic design of clamping force. It has important research value and practical significance to improve manufacturing level. The main contents of this paper are as follows: firstly, the purpose and significance of this paper are described, the research status and development trend of computer-aided fixture design are analyzed and summarized, and the research methods and innovations of this paper are introduced. Secondly, according to the stress state of workpiece in clamping layout, the static equilibrium equation of workpiece under unidirectional constraint of force is established, and the stability analysis model of workpiece is constructed. Based on the position and direction of machining force, the existence analysis method of clamping force is constructed, and the feasibility analysis method of clamping force is constructed according to the existence of clamping force. Then, by introducing the discretization idea of feasible interval of clamping force, the reverse incremental decrement programming algorithm of clamping force is established. Firstly, according to the existence analysis method of the force, it is judged whether the clamping scheme has a reasonable clamping force, if not, the design process ends; if there is, the feasible state of the adjacent two clamping forces is judged according to the feasibility analysis method of the force, if the same, The next clamping force is formed by increasing the size of the same step, otherwise, the next clamping force is formed by reducing the step size by half. This is repeated until the absolute value of the current step is within a given threshold to determine the critical value or critical interval of the clamping force. Finally, the work of this paper is summarized, and the future research direction is described.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TP391.7;TG75

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