Multi-Seam Tracking With a Portable Robotic Welding System in Unstructured Environments

Most welding manufacturing of the heavy industry, such as shipbuilding and construction, is carried out in an unstructured workspace. The term Unstructured indicates the production environment is irregular, changeable and without model. In this case, the changeable workpiece position, workpiece shape, environmental background, and environmental illumination should be carefully considered. Because of such complicated characteristics, the welding is currently being relied on the manual operation, resulting in high cost, low efficiency and quality. This work proposes a portable robotic welding system and a novel seam tracking method. Compared to existing methods, it can cope with more complex general spatial curve weld. Firstly, the tracking pose of the robot is modeled by a proposed dual-sequence tracking strategy. On this basis, the working parameters can be adjusted to avoid robot-workpiece collision around the workpiece corners during the tracking process. By associating the forward direction of the welding torch with the viewpoint direction of the camera, it solves the problem that the weld feature points are prone to be lost in the tracking process by conventional methods. Point cloud registration is adopted to globally locate the multi-segment welds in the workpiece, since the system deployment location is not fixed. Various experiments on single or multiple welds under different environmental conditions show that even if the robot is deployed in different positions, it can reach the starting point of the weld smoothly and accurately track along the welds.

Test and Analysis of TIG-MIG Hybrid Welding Are

A high-speed camera is used to observe the arc starting and arc stabilization process of the TIG-MIG hybrid welding system. Paschen’s law is used to analyze the path of TIG welding arc breakdown under the condition of the conductive channel provided by the MIG welding arc, and the arc starting process of the double arc hybrid welding is determined. The study found that when the electrode spacing is less than 8.5 mm, two molten pools can form a common molten pool after arc initiation of MIG welding; when the spacing is 10 mm, the two molten pools after arc initiation form a “8” shape; When the distance is 12 mm, there is a low temperature zone between the two arcs, which is separated.

Development of a Micro-Habitat Hyperbaric Welding System

The maturation of North Sea platform jackets coupled with high fatigue stresses, fabrication defects, extensive usage, and low-redundancy design eventually result in fatigue cracking. The high sea states in the North Sea further exacerbate the problem. If not closely monitored, fatigue cracks can propagate into and around the circumference of a brace relatively quickly—ultimately leading to brace severance. When confronted with a loss of structural integrity, operators have two options: conduct expensive subsea repairs or decommission the asset. Realising a market gap, DCN Diving has explored alternate repair strategies, leading to the development of the DCN-patent pending µ-Habitat welding system. The µ-Habitat makes it possible to respond quicker, execute subsea repairs faster and guarantee quality at a fraction of the cost of bespoke or modular habitats. Through size reduction, it is possible to reduce the fabrication, production, and handling costs of µ-Habitat. Furthermore, the smaller footprint reduces installation time while simplifying sealing and de-watering offshore, saving time and money. Using a combination of product development facilitators and process improvement methodologies, such as AGILE, SCRUM, and design thinking, reduces the preparation time, making the system incredibly responsive yet flexible. Additionally, using an experienced and dedicated project team in combination with standardised products further minimises the response time to execute a repair. A dry environment, pre-heating, in-process cleaning/grinding, and unrestricted access are fundamental to ensuring high-quality welds. In addition, prototyping, extensive function testing, and mock-ups validate the habitat design before commissioning via factory acceptance testing and mobilisation to guarantee the failsafe performance of the µ-Habitat offshore. The µ-Habitat can play a crucial role in the overall life extension strategy for any offshore structure, ultimately minimising cost, risk and production downtime associated with future subsea repairs.

Three-dimensional integro-differential model of unstationary hydrodynamic process in a liquid-metal pool of underwater arc welding

Wet underwater arc welding is now widely used. At the same time, obtaining high-quality welds with this welding method is an urgent scientific and technical problem due to their saturation with hydrogen and oxygen and the formation of pores. One of the promising directions for solving this issue is the use of an external electromagnetic effect on the liquid metal in the weld pool in order to control the movements of the molten metal flows to improve the degassing processes of welded joints. It is possible to estimate the parameters and efficiency of external electromagnetic influence by means of mathematical modeling of related electromagnetic, hydrodynamic and thermal processes occurring in the welding installation. The article proposes a three-dimensional integro-differential model of a non-stationary hydrodynamic process occurring in the liquid metal of a weld pool in an underwater arc welding system with an external electromagnetic effect. For the equations of hydrodynamics boundary value problems are formed, which, using potential theory, are reduced to a system of integro-differential equations for the vorticity function in the volume of a liquid conductor and a simple vector layer on its surface. For a numerical solution, the resulting system of integro-differential equations is approximated by an algebraic system according to the Krylov-Bogolyubov method. This system of equations makes it possible to determine the velocity field in the liquid metal of the weld pool for any welding modes.

Mixed Reality-Enhanced Intuitive Teleoperation with Hybrid Virtual Fixtures for Intelligent Robotic Welding

This paper presents an integrated scheme based on a mixed reality (MR) and haptic feedback approach for intuitive and immersive teleoperation of robotic welding systems. By incorporating MR technology, the user is fully immersed in a virtual operating space augmented by real-time visual feedback from the robot working space. The proposed robotic tele-welding system features imitative motion mapping from the user’s hand movements to the welding robot motions, and it enables the spatial velocity-based control of the robot tool center point (TCP). The proposed mixed reality virtual fixture (MRVF) integration approach implements hybrid haptic constraints to guide the operator’s hand movements following the conical guidance to effectively align the welding torch for welding and constrain the welding operation within a collision-free area. Onsite welding and tele-welding experiments identify the operational differences between professional and unskilled welders and demonstrate the effectiveness of the proposed MRVF tele-welding framework for novice welders. The MRVF-integrated visual/haptic tele-welding scheme reduced the torch alignment times by 56% and 60% compared to the MRnoVF and baseline cases, with minimized cognitive workload and optimal usability. The MRVF scheme effectively stabilized welders’ hand movements and eliminated undesirable collisions while generating smooth welds.

Exploration of Rotary Friction Welding Technique

Friction welding is a solid-state welding system which welds materials without authentic melting it. This study explores papers of different researchers on the friction welding method and it has been observed that the welding parameters like friction time; friction pressure, forge time and forge pressure highly affect properties of welded joints. The reason for this investigation is to exhort industry and the insightful world regarding advantages of revolving friction welding so the technique may be utilized in an ideal manner.

Dual-robot stud welding system for membrane wall

Purpose The membrane wall is one of the most important components in the boiler industry and numerous studs are welded on its surface. The membrane wall welding still remains a sector intensive in the manual and arduous works. This paper aims to propose a dual-robot system to automatically weld studs on the membrane wall. Design/methodology/approach In this paper, the authors proposed a dual-robot stud welding system for membrane walls. First, the membrane wall is divided into several zones and the welding paths are planned. Then, the pose of the pipes is calculated based on the data measured by light section sensors. The planned paths are compensated by the pose. Finally, the robots weld studs based on the compensated paths. Findings The method effectively eliminates manufacturing errors and welding distortions. The system can weld straight type and L-type membrane walls with high efficiency, high quality and high accuracy. Originality/value The system can weld straight type and L-type membrane walls with high efficiency and high quality. Experiments were performed in a factory to demonstrate the practicability of the method. The dual-robot system with two welding machines has approximately twice the efficiency of the manual welder with only one welding machine. The quality and accuracy of robot welding systems are higher than that of manual welding.

Preliminary Research for Development of MW-TIG Hybrid Welding System

The paper aims to report preliminary researches towards to development of new hybrid welding system by coupling a microwave beam with a TIG torch. The main research was focused on the designing of hybrid system as well as to establish the heating/welding mechanism by coupling two different thermal sources. Therefore, a specific welding chamber was designed taking into consideration the limitations provided by microwave waveguide technical specs, geometrical shape and dimensions of the TIG torch as well as the temperature monitoring during welding process and video surveillance for data recording. A microwave generator with adjustable power from 0 to 1250 W was coupled with a TIG torch and welding power source in order to establish the main parameters for hybrid system. The preliminary researches reported that the MW-TIG hybrid welding could be applied to eutectic joining of materials using low power (up to 600 W) injected from microwave generator as well as low welding current (up to 20 A). The flow of shielding gas have been established initially to 2 l/m. The research related to stabilization of MW-WIG plasma arc have been studied by increasing the flow of shielding gas up to 10 l/m. The results have shown that the microwave generator and TIG torch can be coupled to obtain hybrid-welding process without any matching tuning devices but with risks for damaging the microwave generator. Further researches will be done in order to design auxiliary devices to optimize the hybrid-welding process and to avoid any unwanted plasma arc discharge from welded base materials to microwave generator. In terms of temperature monitoring, an infrared pyrometer has been used. The IR pyrometer was targeted to the base materials in order to be able to measure their temperature without any influences from plasma arc. The results obtained have shown a stable plasma at average microwave power around 400 W even without any TIG current.