模架集成式粉末精密压制成形设备的设计与研究

发布时间：2019-01-30 12:31

【摘要】：在粉末冶金生产实践中，装备水平是制约产品密度和精度的重要因素。针对目前国内粉末成形装备中存在的结构复杂、体积较大，设备成本较高等不足之处；本文提出的研究目标是：研制一种粉末精密成形专用设备，集成上二下三模架，通过集成的油缸驱动，结合闭环控制，能成形高精度、高密度且密度分布均匀的复杂粉末冶金零件。本文为研制出新型粉末精密成形设备提出了集成模架设计方案，它实现压机与模架集成化设计，使得设备结构简单，调试方便，能最大限度发挥粉末成形专用设备的特点，提高成形精度，降低设备价格。针对模架集成式粉末成形设备设计，首先对粉末压制过程中粉末的本构模型进行力学建模，提出一种更符合实验结果的的粉末材料流动应力模型，获得压制过程的载荷；并以此为基础，通过数值模拟方法，研究在典型粉末冶金零件的压制成形过程中,压制载荷对粉末精密成形设备的影响，实现对设备结构设计方案校核；并针对模架集成式粉末精密成形设备的特点设计制造液压系统，综合压机本体和液压系统设计制造配套的控制系统，编制控制软件，并实现了样机研制，并取得以下研究成果：首先要取得压制过程设备的载荷，通过对粉末压制过程中粉末力学模型进行研究，推导出椭球形粉末屈服准则，以实现粉末压制过程的数值模拟，分别模拟计算粉末压制过程的载荷－行程曲线，通过实验和模拟的载荷－行程曲线的对比，分析粉末压制过程中流动应力的变化。结合粉末进行压制实验，对结果进行分析、整理，考虑了Doraivelu的流动应力模型对δ(ρ)的量纲分析，提出用于模架集成式粉末成形设备设计的流动应力模型。采用该模型模拟圆柱试样的压制过程，计算粉末压制的载荷-行程曲线,实验结果表明，该模型更贴近粉末力学行为。采用该模型计算粉末压坯的相对密度分布,与实验值比较,表明该模型模拟的结果较为可靠。采用上述流动应力模型，模拟了典型零件的粉末压制过程，为下一步模架集成式粉末成形设备成形加载提供基础数据。基于多体动力学数值模拟方法，建立了模架集成式粉末成形设备整机接触分析的有限元计算模型，进行了粉末成形设备整机结构强度与刚度分析，得出了整机及其各子结构的变形和应力分布云图，从变形云图中可以得出，各个模板的最大变形挠度均在安全范围之内。将各子结构的最大应力值与其材料的屈服极限进行比较后，可知各零件仍处于弹性变形范围之内，没有发生屈服；计算结果对于结构优化设计具有理论指导作用。对模架集成式粉末成形设备进行模态分析，得到各阶固有频率及对应的固有振型。提取前10阶固有频率及对应的固有振型。设备模态分析计算结果表明，设备的各阶模态频率之间没有重叠，不会产生共振，各阶模态的变形趋势小；从计算结果来看，可以看出整机的固有频率对整机振动的影响，显示出了整机各部分结构振动的强弱分布以及抗振薄弱区，为减少模架集成式粉末成形设备振动和噪声提供了可靠的依据，为成形设备结构动力学优化设计提供了必要的依据。对模架集成式粉末成形设备的液压及控制系统进行研究，液压传动回路中使用插装阀回路、电液比例阀，与光栅尺、压力传感器构成控制回路，实现每个冲头都能独立进行精确的连续轨迹控制，在压制各台面之间高度差别大的多台面零件时，能够使各冲头在压制过程中保持近乎一致的高度变化速率，以较高的工作效率和较高的成形精度压制出密度均匀的粉末零件。成功研制了模架集成式粉末成形设备样机，并成功实现典型零件加工试制，设备满足设计要求，所提出的用于模架与粉末成形设备相集成的设计方案改变传统设备的结构，能最大限度发挥粉末成形专用设备的特点，并形成自主知识产权。该设备的模架由对称分布的集成油缸驱动，独立控制多个模冲实现上二、下三多台面复杂零件的压制。采用光栅尺、传感器和液压系统组合，，检测模冲位置和压力，能进行精确闭环控制，设备精度达到±0.03mm。
[Abstract]:In the production practice of powder metallurgy, the equipment level is an important factor to restrict the density and precision of the product. aiming at the defects of complex structure, large volume, high equipment cost and the like existing in the present domestic powder forming equipment, the aim of the invention is to develop a special equipment for powder precision forming, the invention can be used for forming complex powder metallurgy parts with high precision, high density and uniform density distribution. In this paper, a new type of powder precision forming equipment is designed, and the integrated design of the press and the die base is realized, so that the equipment is simple in structure and convenient to debug, and the characteristics of the special equipment for powder forming can be played to the maximum extent, the forming precision is improved, and the price of the equipment is reduced. The invention aims at the equipment design of an integrated powder forming device of a die frame, firstly, carrying out mechanical modeling on the structure model of the powder in the powder pressing process, and providing a powder material flow stress model which is more in line with the experimental results, and obtaining the load of the pressing process; and based on the model, the numerical simulation side In this paper, the influence of the pressing load on the powder precision forming equipment is studied in the process of pressing and forming of the typical powder metallurgy parts, and the design scheme of the equipment is checked; and the hydraulic system is designed for the characteristics of the integrated powder precision forming equipment of the die frame. The control system for the design and manufacture of the main body and the hydraulic system of the system, the integrated press body and the hydraulic system is designed, the control software is developed, and the development of the prototype is realized, and the following research is made: The method comprises the following steps of: firstly, obtaining the load of the pressing process equipment, and feeding the powder mechanical model in the powder pressing process; In this paper, the yield criterion of the ellipsoidal powder is derived, the numerical simulation of the powder pressing process is realized, the load-stroke curve of the powder pressing process is simulated respectively, and the flow stress in the powder pressing process is analyzed by the comparison of the experiment and the simulated load-stroke curve. In this paper, the results are analyzed and sorted, and the dimensional analysis of the flow stress model of the Dvortexu is taken into account, and the flow of the integrated powder forming equipment for the die set is put forward. The force model is used to simulate the pressing process of the cylindrical sample, and the load-stroke curve of the powder pressing is calculated. The experimental results show that the model is closer to the powder. The relative density distribution of the powder compact is calculated by using the model, and the simulation results are compared with the experimental values. The flow stress model is adopted, the powder pressing process of a typical part is simulated, and the forming and loading lifting of the integrated powder forming equipment of the next step is provided. Based on the multi-body dynamics numerical simulation method, the finite element calculation model of the contact analysis of the integrated powder forming equipment of the die set is established, and the structural strength and the rigidity analysis of the whole machine of the powder forming equipment are analyzed, and the deformation of the whole machine and the sub-structures of the whole machine is obtained. and the maximum deformation deflection of each template is In the safe range, the maximum stress value of each sub-structure is compared with the yield limit of the material, so that the parts are still in the elastic deformation range, and the yield is not generated; and the calculation result is good for the structural optimization design. The mode analysis is carried out on the integrated powder forming equipment of the die set to obtain the inherent frequency of each order. rate and corresponding natural mode. The first 10-order intrinsic frequency is extracted The results of the modal analysis of the equipment show that there is no overlap between the modal frequencies of the equipment, the resonance is not generated, the deformation trend of each mode is small, and the inherent frequency of the whole machine can be seen from the calculation results. The influence of the rate on the vibration of the whole machine shows the strong and weak distribution of the vibration of each part of the whole machine and the weak area of the anti-vibration, and provides a reliable basis for reducing the vibration and noise of the integrated powder forming equipment of the die set, and the structure dynamics of the forming equipment is optimized. The necessary basis is provided. The hydraulic and control system of the integrated powder forming equipment of the formwork is studied. The hydraulic transmission circuit uses the plug-in valve circuit, the electro-hydraulic proportional valve, the pressure sensor and the pressure sensor to form the control loop, so that each punch can be independent. the precise continuous track control is carried out, and when the multi-table part with large height difference is pressed between the pressing surfaces, the punch can keep a nearly uniform height change rate in the pressing process, and the high working efficiency and the higher forming precision pressure can be achieved. The powder parts with uniform density were manufactured successfully. The prototype of the integrated powder forming equipment of the die set was successfully developed, and the typical part processing and trial production were successfully realized. The equipment met the design requirements, and the proposed method was used for the integration of the die set and the powder forming equipment. The design scheme changes the structure of the traditional equipment, and can give full play to the special equipment for powder forming. The mould base of the equipment is driven by an integrated oil cylinder with a symmetrical distribution, and an accurate closed-loop control can be carried out by adopting a combination of a grating ruler, a sensor and a hydraulic system, detecting the position and the pressure of the die,
【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TF37

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