【作者】 李波；

【导师】 李明辉；

【作者基本信息】 陕西科技大学 ， 机械电子工程， 2016， 硕士

【摘要】 合模机构是保证成型模具实现可靠启闭动作的关键部件。全电动注塑机合模机构采用伺服电机作为动力源,可以使模板的运动更加高速、平稳和精确,所以它常常被应用于精密制件生产等高端注塑工程领域。本文以全电动注塑机合模机构为研究对象,根据给定的基本参数和运动简图,进行了合模机构的设计,并分析了合模机构的运动特性。再结合有限元技术、现代优化算法,完成了动模板、前模板、拉杆的静力学分析以及前模板的结构优化。主要研究内容如下：(1)合模机构的设计与优化。首先分析了常见类型的合模机构,然后以电动式曲肘连杆合模机构为研究对象,根据肘杆合模机构的运动简图和主要的技术参数,分析了该类机构的运动特性和力学特性；根据原始数据和参数关系,对合模机构进行了基础设计和三维建模,并且在ADAMS软件中对所建立的模型进行了运动学分析,合模机构基本符合慢-快-慢的运动性能；然后分别以机构力放大比(M)最大化、机构总长(L)最小化、行程比(Ms)最大化作为优化目标,建立了合模机构的优化模型,并运用MATLAB中的fmincon函数对合模机构进行了优化设计,最终获得了性能较好的合模机构。(2)合模机构关键零部件的有限元分析。运用Workbench有限元软件对合模机构的动模板进行了静力学分析,并通过结构改进确定出了质量相对较小且变形均匀的模板设计方案；运用Pro/E和Workbench软件对前模板进行了静力学分析和等质量模型结构参数优化,减小了模板应力集中和变形；同时还分析了注塑机拉杆的受力特性,并通过有限元法对螺纹受力和不同螺母形式下拉杆螺纹段受力进行了研究。结果表明：螺纹受力主要集中在前3个螺纹牙。螺纹段采用悬置螺母紧固,有效的将应力分配到其他螺纹上,最大应力减少了9.86%,螺纹整体受力更加均匀,从而验证了悬置螺母在防止拉杆螺纹牙断裂上的有效性。(3)前模板的拓扑优化。在对前模板进行静力学分析的基础上,运用Workbench软件对前模板进行了拓扑优化,并依据得到的伪密度云图,提出了前模板的修改方案。对修改后的模型再次进行静力学分析,结果显示：通过拓扑优化模型质量减小了4.5%,变形减小了13.5%,从而有效的降低了模板耗材使用量,提高了模板刚度。(4)前模板结构参数的多目标优化。依据前模板静力学分析和拓扑优化结果,建立了以前模板质量和变形最小化为优化目标,以中心凸台高度(P2)、加强筋底面深度(P3)、中心凸台外径(P4)为设计变量的前模板多目标优化模型。并分别通过Workbench中的Direct optimization组件与基于神经网络和NSGA-Ⅱ算法的MATLAB编程方法对该优化问题进行了求解,分别得到了前模板在约束条件下的Pareto最优解。优化后前模板的质量和变形都得到了相应的减小,并且在MATLAB中获得的优化结果优于在Workbench中获得的结果。本课题依据所提供的全电动注塑机合模机构参数,完成了合模机构的设计并对整个机构的运动性能和重要零件进行了优化,达到了预期的设计要求,其中的研究思路和研究方法对其它机械的设计研究也具有一定的借鉴意义。更多还原

【Abstract】 A clamping mechanism is the key mechanical structure to ensure mold achieving reliable on-off movement. The clamping mechanism of all-electric injection molding machine takes the servo motor as power source to make the movement of the moving platen more high-speed, stable and accurate. So all-electric injection molding machine is often applied in precision parts production and other high-end injection molding engineering field.This paper takes the clamping mechanism of all-electric injection molding machine as the research object. According to the given basic parameters and movement, this paper gives the design and analysis of movement characteristics for the clamping mechanism. Combined with the finite element technology and the modern optimization algorithms, we complete the statics analysis of moving platen, front platen, pull-rods and front platen structure optimization. The main contents of research are as follows:(1) The design and optimization of clamping mechanism. This paper studies on the regular types of clamping mechanism. Then, taking the electrical toggle type connecting rod clamping mechanism as the research object, we analyze the clamping motion characteristics and mechanical properties based on its sketches and main technical parameters. According to the the original data and the relationships among parameters, we get the basic design and 3D model of clamping mechanism, conduct kinematics analysis with ADAMS on the model and get the result that clamping mechanism accords with the movement of slow-fast-slow performance fundamentally. Then, we select the maximum of the force amplification(M), the minimum of the structure’s length(L) and the maximum of the stroke’s ratio (Ms) as the optimization goal to build the optimal model of clamping mechanism. Finally, the optimization design is carried out on the clamping mechanism by using the fmincon function in MATLAB to obtain good performance of clamping mechanism.(2) The Finite element analysis of key components of the clamping mechanism. The statics analysis is carried out on the moving platen with Workbench finite element software and it determines the design scheme of the relative small-mass and deformation-uniformity template upon the structure improvement. The statics analysis and the structural parameters optimization of equal mass model is also carried out on the front platen through Workbench & Pro/E. And it reduces the stress concentration and deformation of the template. Besides, we analyze the mechanical characteristics of the Pull-rods and study the stress of the screw thread and the screw thread section under different nut by FEM. The result shows that the threaded force is mainly concentrated on the first 3 threads and the screw thread segment using suspended nut fastening allocates the stress distribution to the other threads, which makes the threaded force is more uniform as a whole and decreases the maximum stress by 9.86%. Accordingly, it verifies the effectiveness of the suspension nut on preventing pull-rods thread fracture.(3) The topology optimization of the front platen. Based on the analysis of statics of front platen, the topology optimization is carried out with Workbench. It proposes a modification scheme of the front platen according to the pseudo-density images. After the static analysis of the modified model, the result shows that the mass reduces by 4.5% and the deformation reduces by 13.5% after the topology optimization, which declines the consumable platen materials effectively, improves the platen stiffness.(4) The multi-objective optimization of structural parameters of the front platen. By the static analysis and the topology optimization results, It establishes the multi-objective optimization model of the front platen on the basis of the height(P2), the reinforced bottom depth(P3) and the outside diameter of convex sets of platen center(P4) with the optimized aim of the minimum of front platen’s mass and deformation. The optimization for the front platen is studied by the Direct Optimization components of Workbench and the MATLAB programming method based on neural network and the algorithm NSGA-II. Finally, we get the optimum solution for Pareto of the front platen under the constraint condition. After the optimization, the mass and deformation of the front platen have been reduced accordingly. It is concluded that the optimization result of the front platen based on MATLAB is superior to the result from Workbench.This topic has completed the design of clamping mechanism based on the provided parameters of the clamping mechanism of all-electric injection molding machine. The optimization is also accomplished for athletic performance of entire motion mechanism and important parts. Finally, this paper achieves the expected design requirements and the ideas as well as the methods of the research also have some reference for other machinery’s design research.更多还原