| Industrial arc welding robot is a mechanical-electrical integration system whose mode of motion is predetermined by the procedure. With the development of technology of industrial robots and welding technology progress, there is about more than50%percent in service industry robot applied to various forms of welding processing fields all over the world, according to incomplete statistics. Industrial arc welding robot technology is widely used in automobile, aerospace, ships domains and so on. Therefore, the reliability improvement of the robot operations appears to be particularly important, because variety of uncertainty factors may have influence on the quality of welding in the process of robot welding. That is to say, the research on the reliability of the arc welding robot becomes a very important tend.This thesis analyzes the reliability of the arc welding robot by the means of qualitative and quantitative analysis. Qualitative analysis method includes the FMECA and FTA analysis, while the quantitative analysis mainly focuses on motion reliability analysis. Based on the FMECA analysis of arc welding robot, it gets failure modes and their effects on the one level and the overall. The researcher also analyzes the criticality of all failure modes, and the FMEA and CA analysis tables of typical subsystem will be given. In the FTA analysis, it is aimed to get overall failure and component failure, the logical relationship of them and fault tree by analyzing the arc welding robot with the method of bottom-up modeling. And then the minimum cut of fault tree has been analyzed. Next, the researcher carries out the Monte-Carlo simulation of fault tree of arc welding robot, probability of occurrence of top event, and probability importance and structural importance of key component. In the process of motion reliability, the researcher analyzes end position and posture error of the arc welding robot, on the basis of influence of input error and structure error, aiming to obtain analysis model of reliability. For input error, the transmission chain error of the system under the influence of the clearance has been considered to get transverse distribution of it; and also obtain precision degradation rule by thinking the influence of transmission error. For structure error, effective length model can be used to analyze the impact of the clearance in order to get transverse error distribution, together with precision degradation rule hinge abrasion. Based on the theoretical analysis, the reliability of the arc welding robot combined with influence of the input error and structure error has been analyzed with the method of Monte-Carlo simulation. Finally, the reliability distribution affected by clearance and the reliability degradation has been given respectively with the simulation analysis. |
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