Abstract
A hydraulic system is a key subsystem of heavy-duty machine tools with a high failure intensity, the failure of which often causes shutdown of production and economic loss in machining. Therefore, it is necessary to implement failure analysis to identify the weak links of system and improve the reliability. For hydraulic system, there is often an amount of failure data collected in field, which help to calculate the occurrence probability of basic events through fault tree analysis method. However, the data are incomplete and uncertain. To address this issue, this study presents a fault tree analysis methodology. Experts’ opinions are utilized, combined with field data based on the Dempster–Shafer theory and rough set theory to fill the incompleteness and eliminate the uncertainty. For application in a case study, a fault tree of the hydraulic system of heavy-duty machine tools is firstly constructed. Then, the importance analysis is performed to help identify the weak links of hydraulic system. The results show the critical basic events affecting the safety and reliability of a hydraulic system.
Highlights
Heavy-duty CNC machine tools (HCMTs) are responsible for the manufacturing of parts related to major pillar industries and national key projects [1,2,3] in fields of aerospace, marine, hydraulic engineering, metallurgy, energy, rail transit, etc
Among subsystems of HCMT, the hydraulic system plays a key role in the power transmission and control of HCMT [4], the failure frequency of which accounts for the largest proportion [5]
This study aims at making the Fault Tree Analysis (FTA) results accurate for a hydraulic system of HCMT
Summary
Heavy-duty CNC machine tools (HCMTs) are responsible for the manufacturing of parts related to major pillar industries and national key projects [1,2,3] in fields of aerospace, marine, hydraulic engineering, metallurgy, energy, rail transit, etc. Constructed a fault tree for tool storage of machining center on a quantitative level and obtained an importance measure of BEs using failure data. (b) The occurrence probabilities of some BEs are too low so that there is a lack of observed data in some cases, in which it is difficult to determine the occurrence probability in an objective manner The collected failure data are used to preliminarily calculate the frequency of BEs. in dealing with a Type I problem, the weight of each possible BE, which commonly leads to one failure, is evaluated using the Dempster–Shafer evidence theory to correct the probability obtained in the first step.
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