摘要
立柱为液压机主要受力部件,起着支撑液压机本体以及为活动横梁导向的作用,由于加工偏载效应、活动横梁横向偏摆运动、液压系统冲击等复合作用,将引起立柱局部瞬态附加应力明显偏大,影响液压机本体结构安全。由于液压机现场环境恶劣,早期立柱应力检测系统均未运行多久即失效,目前国内没有长期可靠运行的液压机立柱应力监测系统。
本文以300MN模锻液压机为研究对象,主要对上一代电涡流式立柱应力检测系统进行了实验测试分析,总结其失效的主要原因,在此基础上,提出了一种数字式液压机立柱应力在线监测方案,并完成了系统总体方案、结构、电气以及软件的设计；系统通过检测立柱受载时的微变形来计算立柱承受的应力,采用数字式微位移传感器为检测核心元件,所有传感器通过一条RS485总线相连,实现了应力信号的数字化采集与传输,提高了系统的抗干扰能力；基于现场总线技术实现与300MN液压机操作系统融合,实现了立柱应力的实时监测、数据归档以及传感器状态监测等功能；使用LS-DYNA软件对300MN模锻液压机进行了有限元接触分析,得出不同模间距下活动横梁偏移对立柱附加应力的影响规律,采用数据拟合的方法得出了立柱附加应力估算公式,可实现立柱附加应力的实时估算,具有工程应用价值；对系统记录的数据进行了分析,验证了附加应力计算公式,得出了300MN模锻液压机立柱应力变化规律。
系统自2009年底成功在300MN模锻液压机上试运行,系统试运行一年多来未出现任何故障,具有较高的可靠性,实现了液压机立柱应力长期可靠监测。所提出的附加应力估算公式可实现立柱附加应力的实时估算,为液压机应力预警提供了技术支撑,对液压机力学规律的进一步研究奠定了基础,为大型液压机的设计提供借鉴和参考。
As the main force components of the hydraulic press, the columns support the body of hydraulic press and guide for the moving beam. The combined effects of processing partial loading, horizontal deflection of the moving beam and the impact of the hydraulic system would cause columns'local transient additional stress significantly increased and affect the safety of the body structure. The early column stress detection systems were all failed by running only a shot time because of the hostile site environment of the hydraulic press. At present, there hasn't been any long-term and reliable columns'stress monitoring system of the hydraulic press in the country.
In this paper, the 300MN die forging hydraulic press was choused as the research object. The experiment of eddy-current columns'stress detecting system was tested to identify the main failure reasons of the previous generation. And on this basis, a program of digital hydraulic columns' stress online monitoring system was proposed. The overall system plan, structural design, electrical system design and software design were all been completed. The system calculated the columns stress by detecting the micro-deformation of the column when loaded. The digital micro-displacement sensors were used as the core components, and all sensors were connected to a RS485 bus, so both the signal acquisition and transmission were digitizing, which improved the capacity of anti-jamming of the system. Based on the filedbus, the columns'stress monitoring system integrated with the 300MN die forging hydraulic press operating system, had the functions of real-time columns'stress monitoring, data archiving, and sensor condition monitoring. The finite element contact analysis of 300MN die forging hydraulic press was did by LS-DYNA to analyze the influence on columns'additional stress with different mode spacing caused by the horizontal offset of moving beam. Columns'additional stress estimation formula was concluded using the method of data fitting, which can estimate the columns'additional stress real-time. It has the engineering value. The data recorded by the system was analyzed to verify the columns'additional stress estimation formula. The change rule of 300MN die forging hydraulic press columns'stress was summed up.
The columns'stress online monitoring system has been trial ran on the 300MN die forging hydraulic press since the end of the year 2009. There has not any breakdown during the system operation time, so the system has high reliability, it can realize long-term reliable monitoring of the columns'stress of hydraulic press. The estimation formula proposed can estimate the columns'additional stress real-time, which provide d technical support for early warning of hydraulic press'stress. The research of this paper laid the foundation of hydraulic press'mechanical laws for further research and provided reference for the design of huge hydraulic press.
引文
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