微小孔精密挤压研磨工艺与控制方法研究

发布时间：2018-02-15 20:11

本文关键词： 微小孔挤压研磨模糊控制专家系统模糊神经网络　出处：《上海大学》2016年博士论文　论文类型：学位论文

【摘要】：微小孔零件在众多行业都发挥着重要作用,然而,微小孔零件内部的毛刺和锐利棱角处理不好,对设备的性能将产生很大的影响,甚至会造成恶劣的事故。因此,各行各业针对孔形零件的去毛刺和光整投入了大量的人力物力进行研究,并取得了一定的效果。但是由于微小孔零件要求越来越高,常见的去毛刺方法已难以满足。磨料浆体流采用低粘度、悬浮性和流动性优良的研磨介质对微小孔工件进行加工,可以达到去毛刺和光整的效果。又由于采用隔离和在线测量方法,使加工过程中的流量变化能被实施监测和控制,所以采用磨料浆体流的微小孔精密挤压研磨能够一次加工即得到很高的流量一致性。这是其他去毛刺和光整方法所难以实现的。本文以具有代表性的微小孔零件——针阀体的挤压研磨为例,对流量监测方法、在线实时加工工艺进行了研究,并将智能算法与专家系统结合起来进行加工建模和参数优化。本文根据需求搭建了加工平台,并在该平台上对一些可能的加工工艺的加工结果进行比较,证明了前述各方法的先进性。具体研究成果如下：对微小孔进行精密挤压研磨必要性和可行性进行了分析,研究并指出本系统所用的研磨介质的优越性。根据精密挤压研磨加工的具体要求,分析研究了加工涉及的评价指标和具体参数,为最终的控制实现提供基础。在加工平台建造前采用功率键合图对系统的液压过程进行仿真分析和计算,并采取了增量式PID算法来稳定流量测量处压力,提高了流量控制的精度。针对加工中流量持续变化、流量值小、实时性要求高的特点,从实时性、准确性和数据显示的合理性角度出发,对流量处理算法进行了研究。由于加工时,加工压力会人为改变,故通过数据拟合,在加工中前期采用等效流量计算公式来计算实际流量。分析已有在线加工方法的不足,采用新的加工工艺,构造了在线加工过程基准曲线,并采用双模式联合控制作为在线控制方法,即加工的中前期,采用模糊控制方法进行加工,在加工的末期,采用定压加工的方式,保证加工流量与流量试验台所测量流量的对应,从而使加工质量和效率的得到有效提升。在模糊控制阶段,对流量增速基准值和压力差值采用非线性量化的方法进行模糊化,对流量增速误差和流量增速误差变化率以及输出的压力增量采用变论域方法进行模糊化,为减小计算量,提高运算效率,伸缩因子根据流量增速基准值和压力差值的量化等级得到。由于研磨介质的研磨能力在加工过程中的变化,以及其他加工条件的变化都将导致加工数据会有较大差异,所以本文建立了专家系统,以保存大量的加工数据和积累加工经验,为后续生产服务。本文的专家系统主要讨论加工建模和参数优化方面的工作,对于新的加工情况,专家系统采用正向推理进行参数优化推理,或者采用模糊神经网络和粒子群优化结合的方式进行参数优化,首先对加工过程进行训练和建模,建立多目标优化模型,然后采用粒子群优化算法加载训练模型,给出非劣解作为新的加工参数组合。本文研究了微小孔精密挤压研磨的在线测量方法、在线工艺和控制方法、参数优化以及系统的具体实现,并在各种加工条件下进行了实验分析和比较,证明本论文的理论研究成果能有效提高微小孔挤压研磨的加工精度、加工效率和系统的稳定性。
[Abstract]:Micro hole parts play an important role in many industries, however, the micro hole parts of the internal burr and sharp edges are not handled properly, the performance of the equipment will have a huge impact, and even cause severe accidents. Therefore, all walks of life for hole shaped parts deburring and finishing put a lot of manpower study, and achieved certain results. But due to the requirements of the micro hole parts is more and more high, the common deburring method has been difficult to meet. The abrasive flow with low viscosity, the micro hole processing work piece suspension and flow of fine grinding media, can reach to the effect of deburring and finishing. Because of the use of isolation and online measurement method, the change of flow process can be implemented to monitor and control, so the use of abrasive slurry flow micro hole extrusion grinding to a precision machining to obtain very high The flow of consistency. This is the other deburring and finishing methods are difficult to achieve. The ground is representative of the micro hole parts, needle valve as an example, the traffic monitoring method, online real-time processing technology was studied, and the intelligent algorithm and expert system are combined to process modeling and parameters optimization. This paper built the processing platform according to the demand, and on the platform of processing on some possible processing results are compared, it proves the progressiveness of the above methods. The results are as follows: the micro hole extrusion precision grinding necessity and feasibility analysis, research and points out the superiority of grinding medium by using this system. According to the specific requirements of precision extrusion grinding process, analyzed the evaluation index of processing involved and the specific parameters, provide the basis for the final implementation in the control. The processing platform built before using the power bond graph of hydraulic system simulation analysis and calculation, and take the incremental PID algorithm to stabilize the pressure and flow measurement, improves the flow control accuracy. According to the continuous change in the processing flow, the flow is small, the characteristics of real-time requirement, from real-time, rationality angle accuracy and data display based on flow processing algorithm is studied. The processing time, processing pressure will be artificially changed, therefore, by fitting the data in the process of pre equivalent flow calculation formula to calculate the actual flow. The analysis of the existing problems of online processing methods, the new processing technology, construct the base curve online processing, and the use of double mode combined with online control as control method, namely in the processing stage, the fuzzy control method is used for processing in the processing stage, the constant pressure and The way to ensure the processing flow and the corresponding flow test rig for measuring flow, so as to effectively improve the quality and efficiency of machining. In the fuzzy control of traffic growth stage, the reference value and the pressure difference method was used to quantify the nonlinear fuzzy, the flow rate and flow rate error rate and output error the pressure increment using the variable universe fuzzy method, to reduce the amount of computation, improve the computational efficiency, the expansion factor according to the growth rate of flow and pressure difference between the reference value of the quantization level. Because of the change of grinding medium capacity during processing, change and other processing conditions will lead to processing data will be a big difference so, this paper established the expert system to save a large amount of data processing and the accumulation of experience in processing, for the subsequent production service. This system mainly discuss the construction process Work and optimize the parameters of die for processing new, expert system uses forward reasoning parameter optimization reasoning, or by using the fuzzy neural network and particle swarm optimization with the method of parameter optimization, first training and modeling of the machining process, a multi-objective optimization model is built, then the particle swarm optimization algorithm loading training model and as the new solutions of the processing parameters are given. Combination of non online measurement method is studied in this paper. The micro hole extrusion precision grinding, on-line process and control method, parameter optimization and system implementation, and analyzed and compared under various processing conditions, the processing precision of that research results of this paper can effectively improve the micro hole extrusion grinding, the machining efficiency and stability of the system.

【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG376;TG580.68;TP273

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