Stress Monitoring System Developed For Hydraulic Press Column And Its Law Of Additional Stress

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.