| As an important part of shield machine,cutter head component is a thick plate welding process product with complex structure.In recent years,with the rapid development of China's rail transit industry,the market demand for shield machine and its cutter head components is increasing.At present,the manual welding of cutter head parts is inefficient and the quality is difficult to be guaranteed,and the automatic welding production is seldom used in practice,this paper designs and develops the welding robot workstation of cutter head components according to the provincial key research and development project of Jinan Heavy Industry Co.,Ltd."the welding robot system of shield machine super thick plate complex large structure parts".The main work of this paper is as follows:1.Overall design of mechanical structure of welding workstation.According to the design requirements and work flow of the cutter head parts changed from manual welding to robot welding,the hardware scheme is studied and developed.The hardware system of 11 DOF welding workstation,which combines 6-DOF arc welding robot,2-DOF U-type positioner and 3-DOF rotating boom,gives the overall layout of the welding workstation.2.Welding scheme design of welding workstation.According to the welding quality requirements of cutter head components,the welding process is selected.MAG welding is used to realize multi-layer and multi pass welding of thick plate.Through the research of welding supporting equipment and DeviceNet communication,the welding process sequence is reasonably planned to ensure the reliable welding quality.3.Design of control system for welding workstation.Combined with the concept of DCS,a complete set of hardware,software and upper human-computer interface scheme for the control system of welding workstation is designed:Taking SIEMENS S7-1200PLC as the controller,the communication architecture of the control system is planned and configured,studies the I/O point distribution and electrical schematic diagram of welding workstation,the control programs of PLC and robot end are compiled,the design of HMI and PC interface is completed.4.Vision based welding adaptive control of welding workstation.The welding adaptive control studied in this paper is a compound control which combines the closed-loop weld sensing and open-loop weld bead planning.Firstly,an accurate mathematical model of welding sensor based on active vision technology is established;Secondly,in order to obtain 3D coordinates of welding feature points,aline structured light stereo vision algorithm based on inverse PNP problem is proposed by studying the algorithm of direct linear transformation of PNP problem.The algorithm can realize the solution from 2D image coordinates of welding vision to 3D wiki coordinates of robot without the aid of calibration tools.At the same time,three specific implementation ways to improve the accuracy of the algorithm are given;Thirdly,an adaptive control strategy of weld bead planning is studied and put forward to realize the adaptive control of layered welding of cutter head components;Finally,the algorithm of welding feature point recognition based on slope method is optimized to improve the accuracy of welding adaptive control.The welding robot workstation of cutter head component realizes the automatic welding of thick plate represented by cutter head component.After long-term operation and repeated tests,the welding workstation designed in this paper has passed the internal acceptance of the enterprise:the overall operation is stable,the welding quality is reliable,and the user feedback is good,which is expected to be put into production in the near future. |
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