Jiao Xiangdong

Application Study of Edge Detection for Droplet in Laser Enhanced GMAW Welding

Ambient pressure has a certain inhibiting effect on underwater welding droplet transfer and the stability of welding process. Good droplet transfer of underwater welding plays an important role in improving repairing quality of underwater structures. As an additional droplet separating force, laser provides effective means in improving the welding quality. For quantitative analysis and comparison of laser enhanced effect on droplet transfer, a high-speed camera system to shoot the process of welding droplet transfer was designed and by adopting the frequency domain operation, a filter aiming at image processing of welding droplet was also designed to filter the ambient noise and diffraction fringe. Through edge detection algorithm, edges of droplet images were detected, and the size of droplet was computed accurately with welding wire as the reference. At last, droplets’ statues under different welding parameters were compared. The results show that the clear images of GMAW droplet separated from the noise background can be acquired, which makes the high-precision quantitative analysis of laser enhanced effect possible. All of the results lay a foundation for further test of laser enhanced hyperbaric underwater welding.

Welding robot system applied in sub-sea pipeline-installation

Purpose – The aim of this study was to develop a new generation of automatic systems based on cutting-edge design and practical welding physics to minimize downtime caused by defects and machine faults on the barges. Automatic welding has been used frequently on offshore pipeline projects. Design/methodology/approach – An automated welding robot system for sub-sea pipeline installation was constructed. The system utilized the double-car double-torch welding, which is light-weight and compact, suited for offshore applications. Several state-of-the-art technologies were integrated into the control system design, including a heterogeneous network based on EtherCAT technology, network communications based on CANopen, motor synchronization, all-position welding, etc. In addition, the utilization of the CAN bus reduced the number of cable lines and increased the extensibility of the proposed welding robot system. An internal clamp with copper shoes assured a nice root weld and narrow bevel design and the welding efficiency was improved accordingly. Findings – The trial was carried out to verify the rationality and effectiveness of the proposed automated system. The deposition rate of the backing welding could reach 17.78 kg/h; the average time for each welding was 340 s. This system was unique in that it features a dual-torch welding head that allowed for the deposition of one run with twice as much material as a single torch head. The experiment showed that the double-vehicle double-torch mode can greatly improve the welding efficiency of pipeline installation during the welding process. Research limitations/implications – The automated welding robot system will be applied to offshore pipeline projects. Originality/value – This robot is the first submarine pipeline installation welding robot to use a heterogeneous network based on EtherCAT technology. Various aspects of the submarine pipeline installation welding robot’s design and performance were discussed, including mechanical body design, control system design and welding process specification.Purpose – The aim of this study was to develop a new generation of automatic systems based on cutting-edge design and practical welding physics to minimize downtime caused by defects and machine faults on the barges. Automatic welding has been used frequently on offshore pipeline projects. Design/methodology/approach – An automated welding robot system for sub-sea pipeline installation was constructed. The system utilized the double-car double-torch welding, which is light-weight and compact, suited for offshore applications. Several state-of-the-art technologies were integrated into the control system design, including a heterogeneous network based on EtherCAT technology, network communications based on CANopen, motor synchronization, all-position welding, etc. In addition, the utilization of the CAN bus reduced the number of cable lines and increased the extensibility of the proposed welding robot system. An internal clamp with copper shoes assured a nice root weld and narrow bevel design and the weldin...

Development of automatic welding system applied in subsea pipeline laying

In order to explore deep water oil and gas fields in South China Sea area, an automatic welding system applied in subsea pipeline laying has been developed, which has several features such as GMAW process, two welding carriages with dual torch, narrow gap and internal line up clamp fitted with copper backing rings. The welding carriage is specially designed for offshore application, so it is compact and lightweight. The control system of the automatic welding station is constructed on the CANOpen bus and Ethernet technologies, so the flexibility and reliability of the system are greatly improved, and the pipeline welding process also can be monitored remotely.

Numerical simulation onto the preliminary period of Friction Hydro Pillar Processing in Friction Stitch Welding

Numerical simulation technology by Finite Element Method (FEM) based on solid mechanics is adopted to study the contact properties of Friction Hydro Pillar Processing (FHPP) at its preliminary period during the process of Friction Stitch Welding (FSW). The analysis through three dimensional elastoplastic static FEM model indicates that the normal stress on the contact interfaces increases gradually along the radial direction from center to the outside, and the metal stud will become thickening when the applied external load approaches to a certain value. The analysis through three dimensional thermal mechanically coupled FEM model indicates that the temperature on the contact interfaces increases rapidly, but the highest temperature value during the whole process is lower than the melt point of metal involved. As to the normal stress distribution, it is relatively high at the marginal node while relatively low at the central node, and the normal stress will decrease gradually with the elapse of time.

Research on the Control System for Automatic Pipeline Welding Based on CANopen

Automatic weld has been used frequently on pipeline projects. The productivity and reliability are most essential features of the automatic welding system. The welding system based on CANopen consists of welding carriage, master control unit, wire feeding box, welding power and welding station. The positioning system of welding carriage can detect accurately itself angle position so that welding system can weld with mated welding parameters at any position. The welding process parameters at every position are calculated with interpolation, the welding system implements that welding process parameters change continuously. The system has the network function via which the welding task data can be transmitted and the welding process data can be monitored. The system has the self diagnostic function which facilitates maintenance and repairs.