Research And Implementation Of Automatic Welding Machine Control System For Pipe Outer Circle

With the development of society and economy,the construction of oil and gas pipeline has increased rapidly,and the automatic welding technology of large caliber pipeline has developed rapidly.Oil and gas pipeline welding is often carried out in the field environment,and it has high requirements for the portability,welding efficiency and welding quality of the welding equipment.At present,at home and abroad,a series of welding processes such as bottom connecting,filling and face covering are widely carried out by a welding trolley that walks along the circular cross section of the circular pipe.It still has a lot of room for improvement in mechanical structure,operation mode,labor intensity and so on.In this paper,a new control system of pipe outer circle automatic welding machine is put forward.In combination with database technology and cloud computing technology,the welding process parameters and empirical data are uploaded to the cloud.The shared process parameters and experience data not only reduce the welder's labor intensity,but also reduce the dependence on welder's operation experience,which greatly improves the automation level of welding.The control system contain two parts: the one is lower computer and the other is upper computer.The lower computer was designed with STM32 series MCU based on ARM cortex-M4 core.In this paper,step motor and the corresponding mechanical transmission structure are used to hold the welding gun to complete the welding action.The Maclaurin formula is used to design an algorithm to simplify the calculation of the smooth speed of the stepper motor.And it is applied to control the stepper motor based on STM32.The attitude calculation algorithm based on the MPU6050 six axis motion sensor is studied and the design of software and hardware are designed in this paper.It is applied to the detection of the position of the pipe outer circle welding and the automatic control of the position based welding parameters.The process and principle of uC/OS-III's transplantation to STM32 micro controller are studied and used in the software design of the lower computer.The upper computer software is designed with Qt development environment,whitch is a cross platform software development tools.The Qt development architecture is studied,and the upper computer software based on the Windows system is designed.A convenient and easy to use game handle is used as an input device for the operation of the upper computer.The video monitoring system of weld pool is an important part of the intelligent welding machine,its requirements for the shutter and dynamic range of the camera are higher.Structure of special camera for monitoring welding pool and backlight shooting principle are studied in this paper and the principle of spectral filtering for weld pool and welding arc is analyzed.The Shenzhen Helica Electronics Co.Ltd's production HL-3070 welding pool dedicated video camera is used for real-time collection of molten pool video.Then the video would be transferred to the upper computer by Wireless video module.And finally the video is displayed in real-time to the welder.Thus,the labor intensity and ultraviolet radiation damage would be less compared with a close watch of the weld pool.The welding power system is a welding equipment that provides welding energy,wire material and welding protection gas.This paper uses the TDN-3500 series carbon dioxide gas shielded welding power supply system produced by the Beijing Time Welding Company.A simple ModBus master device protocol based on STM32 and a ModBus command frame generation software module based on the upper computer are designed.The adjustment of the current,voltage and start and stop parameters of the welding power supply system is realized by this paper.So that the process parameters of welding can be controlled in real time.At present,the pipeline automatic welding machine system is preliminarily applied to the construction projects of some long distance pipeline and chemical pipeline of the China National Chemical Engineering No.16 Construction Co.,Ltd.The success rate of one time welding is 96%,it meets the requirements of pipeline welding well.