Welding Position Research Articles

Weld seam positioning method for structural reinforcement based on 3D point cloud

Abstract Machine vision technology assists welding robot weld positioning, which can significantly improve welding accuracy and efficiency. This paper delves into a 3D point cloud-based positioning technique specifically tailored for structural reinforcement welds, utilizing the high-precision 3D structured light camera to get 3D point cloud data from the surface of the reinforcement structures, subsequently conducting a comprehensive analysis of the weld’s geometric characteristics. When the weld seam position can be directly collected, the side plate plane and the bottom plate plane of the reinforcement can be divided by the random sample consensus method. The weld points with rich curvature characteristics can be quickly and reliably selected according to the plane constraint. When the weld position cannot be measured directly, the prediction of the weld position is realized by extracting the edge of the upper surface of the reinforcing rib in the depth map and combining the plane normal vector of the base plate and the point laser correction vector. The experimental results show that this method can accurately locate the weld seam with high accuracy in both working scenarios.

A Primary Study on the Applicability of Gel-Type Filler Materials to Root Pass Welds of the Thick Plate

Welding generally uses filler material to create deposited weld metal. Filler materials play a significant role in welding by providing the material needed to fill and form the joint. Existing filler materials are limited in the workspace and welding position and need help responding flexibly to welds of complex shapes. This study conducted primary research to develop a gel-type filler material with adhesion and flexibility that can cope with limited workspace and location. We attempted to provide a new approach to welding by mixing metal powder and binder to create a gel-type filler material. Root pass welding of thick plates was performed using a laser heat source. The bead appearance and cross-section of the weld zone were observed according to the type and composition of the metal powder, the binder content, and the method of synthesizing the metal powder. The physical characteristics of the weld were analyzed through observation of the hardness and microstructure of the weld.

Development of automation and monitoring methods for narrow-gap hot-wire laser welding using camera images

AbstractIn this study, an image-based method was developed for hot-wire laser narrow gap welding. The welding process was monitored based on image information processed using semantic segmentation, a method of classifying images by pixel. To control the welding position, an experimental system was configured that automatically follows the welding position by recognizing the position of the welding groove from the image during welding. In monitoring weld defects, a method was developed to predict the lack of fusion occurring on the wall surface using brightness information near the wall surface. For the lack of fusion occurring at the bottom of the groove, a defect detection method was developed by monitoring the molten pool shape using semantic segmentation. Defects were generated by intentionally reducing the laser power, and the defects were monitored from images taken during processing. In the unstable state where the laser power was reduced, the shape in front of the molten pool became unstable, and the occurrence of defects was monitored by capturing the shape change. In conclusion, this research made it possible to control and monitor the welding process with a single camera.

Influence of robot-guide strategies on the geometry of directed energy deposition components

Directed energy deposition (DED) for additive manufacturing applications is commonly realized by the usage of industrial robots. The DED processing end effectors are usually mounted on industrial robot systems and can, therefore, be moved and oriented in up to many degrees of freedom. However, the design of the powder nozzle and the programming of the robot can limit the movement options. For this reason, translational movements, as with conventional 3D printers, are still common today. The end effector is usually guided horizontal over the component surface although welding in position (PA) is preferred in general. It may be necessary to tilt the end effector in order to gain advantages during processing due to the constrained position. This is particularly advantageous for overhang structures and is often realized with the help of a turn-tilt positioning table in combination with an industrial robot. However, this approach is, in some cases, not possible due to geometrical constrains. To extend applications in this direction, advanced methods for slicing the components and programming the robot movements are necessary. The main aspect of this work is the development, testing, and evaluation of a multidimensional DED manufacturing approach. This is tested on a thin-walled component with defined overhang areas and compared with conventional approaches. Different strategies are assessed in terms of the geometrical match of the target geometry. Influences of strategies on the results are evaluated. It can be shown that multidimensional path planning approaches lead to a better match of the target geometry.

Quality evaluation and crack cause analysis of a type B sleeve service welding

Abstract Type B sleeve repair technology is important in service welding repair because the quality of fillet weld directly affects the sealing and bearing capacity of Type B sleeve repair. In this paper, a cover weld crack at 0 o ‘clocks of fillet weld found by non-destructive testing is analyzed. The tensile strength of fillet weld and longitudinal weld is much higher than the technical requirements of X80 steel grade pipe, the welding material belongs to a strong matching state, and its impact toughness value is low. At the same time, the hardness test was carried out at the fillet weld, and the hardness of the tube body at the welding position of the cover was higher than that at other positions, and there was a risk of cracking. The defects were dissected as hot cracks, and the reason was related to the strong matching of the selected welding material. It is suggested that when selecting welding materials for lap fillet welding, it is possible to try to reduce the matching strength level of the weld without affecting the sealing and bearing capacity.

Numerical characterisation of reaction forces’ contribution to initial stiffness in speed-lock beam-to-upright connections

This article presents a detailed numerical model of speed-lock (boltless) beam-to-upright connections in steel storage pallet rack systems. The model is capable of predicting initial stiffness and characterising the reaction forces of connector-to-upright interactions. The study examines nine configurations, combining three types of uprights and three types of beams with a common connector. Initially, experimental tests were conducted using the monotonic cantilever test method according to EN 15512 standard, with initial stiffness calculated using a standardised version of the initial stiffness method. Subsequently, a numerical analysis was developed through a finite element model based on the experimental setup. The model introduces new geometric details, evaluating each impact on behaviour, particularly on initial stiffness. Results show that numerical accuracy improves with detailed components such as inclined tabs, more detailed perforations, and 3D weld modelling. The contribution of reaction forces of connector-to-upright interactions to initial stiffness was analysed, considering the impact of the rotation centre’s position. It was found that a lower rotation centre position reduces the connector-to-upright lateral contact contribution while increasing tab-to-slot interaction contributions. The impact of beam height and beam weld position on initial stiffness was also analysed, with results showing that increasing these variables consistently led to increased initial stiffness. Finally, the rotation centre’s position was shown to evolve throughout the test, redefining the contribution of interactions. It clarified that connector-to-upright lateral interaction and tab1-to-slot1 and tab2-to-slot2 interactions have the highest contributions. This information is valuable for rack manufacturers to improve, optimise, and ensure the safety of their designs.

Deformation behavior of plastic zone at crack tip of 304 stainless steel

AbstractIn this paper, the deformation behavior of plastic zone at crack tip during crack propagation of 304 stainless steel was studied. Firstly, the fatigue crack propagation tests of 304 stainless steel material were carried out. Combined with digital image correlation (DIC) technology, the strain field data of plastic zone at crack tip, the size of plastic zone, and the strain evolution law of crack tip region at different positions were obtained. Then, combined with the theoretical model and the numerical model, the theoretical, numerical, and experimental results were compared to verify the accuracy of the model. Finally, the effects of cyclic loading, specimen thickness, and weld position on plastic zone at crack tip were analyzed. The research results provide a reference for accurately predicting the fatigue crack growth of 304 stainless steel.

Influence of double-pass friction stir welding and blank position on formability of aluminum tailor welded alloy blanks

Influence of double-pass friction stir welding and blank position on formability of aluminum tailor welded alloy blanks

Analysis of Dye-Penetrant Test, Tensile Test, and Bending Test Results of Shielded Metal Arc Welding (SMAW) on Carbon Steel ASTM A106 Grade B Pipes in 6G Welding Position at PPSDM Migas Cepu

Analysis of Dye-Penetrant Test, Tensile Test, and Bending Test Results of Shielded Metal Arc Welding (SMAW) on Carbon Steel ASTM A106 Grade B Pipes in 6G Welding Position at PPSDM Migas Cepu

Research Review and Future Directions of Key Technologies for Welding Robots in the Construction Industry

The rapid development of the construction industry has highlighted the urgent need for enhanced construction efficiency and safety, propelling the development of construction robots to ensure sustainable and intelligent industry advancement. Welding robots, in particular, hold significant promise for application in steel structure construction. However, harsh construction environments, variable construction structures, and complex construction conditions present critical technical challenges for weld position, path, and quality for welding robots. This paper aims to provide a focused review of the key technical difficulties faced by welding robots in the construction industry, starting from the progress in research and applications. The review identifies the current state of welding robot technology, the technical bottlenecks encountered, and the potential solutions to these challenges, offering valuable insights for the research and development of construction robots.

Mewujudkan Pembelajaran Kejuruan yang Nyaman: Implementasi Kaidah Ergonomi dalam Praktek Pengelasan di SMK Negeri 1 Purworejo

Various welding positions and extended durations of welding practice sessions can contribute to Musculoskeletal Disorders (MSDs) complaints among Vocational High School (SMK) students. MSDs encompass conditions that manifest symptoms affecting muscles, nerves, tendons, ligaments, joints, cartilage, and the spinal cord. The implementation of an ergonomic welding table may assist welding operators in working on projects for prolonged periods with a reduced risk of MSDs complaints. This article reports on the community service activities conducted by the Vocational and Mechanical Engineering Education research group at Universitas Sebelas Maret in developing and implementing an ergonomic welding table at SMK Negeri 1 Purworejo. Ergonomic parameters used for reference include the Nordic Body Map (NBM), Rapid Entire Body Assessment (REBA), and Rapid Under Limbs Assessment (RULA). The pre and post experiment analysis indicates a decrease in NBM, REBA, and RULA scores following the implementation of the ergonomic welding table, suggesting the potential for minimizing MSDs complaints.

Automatic welding seam tracking and real-world coordinates identification with machine learning method

In the automatic welding process, the precision of the welding position significantly influences welding quality, relying heavily on the accurate identification of the welding seam. However, in complex and unstructured welding environments, such as those with strong arc lights, welding splashes, and thermal-induced deformations, various disturbances present a significant challenge to identify the welding seam. This paper introduces a cost-effective welding seam tracking model constructed using a laser line and a fixed viewpoint single RGB camera. The model's primary objective is to detect a chain of welding-seam points in both captured images and real-time camera feeds. The paper presents the techniques for camera calibration, laser detection, and the use of artificial intelligence to establish a real-world coordinate frame. The process begins with camera calibration using the OpenCV library to filter noise and undistort images. Subsequently, the thresholding technique is employed for color image segmentation, isolating the laser sensor light on the workpiece. An algorithm is then introduced to detect welding spots. Finally, the image coordinates are converted to world coordinates using two machine learning methods: Random Forest Regression and Gradient Boosting Regression. Experimental demonstrations were conducted at different positions on the object to assess algorithm precision. The results indicate average deviations of 0.83 mm, 0.74 mm, and 0.77 mm for X, Y, and Z coordinates, respectively, which fall below the expected standard deviation of 3 mm. Despite the overall consistency of the program, slight noise from environmental lighting may still exist. In conclusion, the proposed welding seam tracking method and coordinate conversion program have proven effective and cost-efficient, with potential for future improvements.

3D Modelling of Layer-by-Layer Heat and Mass Transfer in Wire Arc Additive Manufacturing

A comprehensive three-dimensional transient computational fluid dynamics (CFD) model was developed to analyze the thermophysical phenomena in the arc wire additive manufacturing (WAAM) process. The model includes droplet impact, gravity, heat and mass transfer, molten metal flow, and solid-liquid phase changes. By integrating the mass, energy, momentum, and volume of fluid (VOF) equations, a layer-by-layer additive process was successfully simulated. The accuracy of the model was validated by comparing the simulation results of single-pass single-layer weld beads at three welding positions with experimental data. The established model was utilized to quantitatively investigate the effects of three crucial welding process parameters–welding direction, droplet transfer frequency, and initial temperature–on the multi-layer cladding process. These findings suggest that the use of opposite welding directions in two adjacent layers can result in a well-distributed overall morphology of the weld bead. Moreover, the high initial droplet temperature enhanced the inclination of the weld bead morphology while decreasing the height of each layer. However, the high droplet transfer frequency caused both the height and width of the weld to increase. This research contributes to explaining the formation mechanism of the multi-layer cladding process and offers insights for improving weld bead morphology. This provides valuable theoretical guidance for the process optimization and control of arc additive manufacturing technology.

Design and manufacturing of Welded Vacuum Testing (WVT) tool

To ensure the quality of welded joints in the hull area, welding testing is very important and must be carried out. But unfortunately, currently the quality testing process of welded joints was still limited to penetrant tests and lime tests. The purpose of this study was to obtain a portable welding testing machine that was able to obtain fairly accurate test results on hull welding defects using a vacuum system. The research method is experimental by involving data collection through field experiments, testing is carried out with the resulting weld defect research subjects and the length of testing time on 1G and 3G position welding. The results of the study by compared tests among Welded Vacuum Testing (WVT) machines, Magnetic Particle tests (MP), and Penetrant Tests (PT). The three experiments detected leaking weld defects, spark sparks, pinholes, overlaps, and undercuts. For test results with machines made, welding defects that were successfully detected were leaks in the 1G position welding workpiece and undercut in the 3G position welding workpiece. Air bubbles at a vacuum pressure of 0.2 bar are detected, meaning that there is a defect in the welded joint. This tool can be used in bilge testing.

Enhancing all-position weldability and weld quality via an innovative laser-GMAW hybrid welding technique with copper liner

The change in welding position results in varied effects of gravity on the weld pool behavior. Conventional welding methods face difficulties when adjusting to welding in different positions. To address these challenges, a novel all-position welding technology, laser-GMAW hybrid welding with copper liner (CL), was introduced. CL serves a dual purpose. First, from flat to vertical welding, it supports the weld pool across various positions, thereby preventing root sagging or burn-through defects at the root of the weld in this range. Second, it facilitates accelerated weld pool solidification and inhibits its downward movement during vertical to overhead welding positions, forming the back continuous reinforcement. To quantitatively analyze the impact of CL on the temperature field during welding, finite element software was employed in this study. Moreover, the study also explored the effects of the size of the forming groove, welding current, and laser power on the weld appearance during overhead welding. As a result, with constant welding parameters, ideal welds with continuous back reinforcement were successfully achieved at five representative positions within the 0–180° range.

A vibration-resistant detection method of weld position and gap for seam tracking of Z-weave GMAW

A vibration-resistant detection method of weld position and gap for seam tracking of Z-weave GMAW

Influence of welding parameters on the formation of U-rib fillet welds in single-sided welding of steel bridge panels

It is difficult to reach the requirement of 80% U-rib weld penetration in the practical application of single-sided welding of steel bridge panels. Meanwhile, full penetration has to be avoided. In this study, efforts are made in order to achieve fillet welds with 80% and above penetration consistently. The effect of welding parameters on the formation of single-sided U-rib fillet welds is investigated. This work has revealed that U-rib fillet weld penetration is presenting an upward trend as the welding current increases under specific welding conditions, and full penetration was observed at the current of 325 A. With the increasing distance between the filler wire and the root of the weld, the U-rib penetration reduces. As the torch angle increases during ship position welding, the U-rib penetration will first increase and then decrease. The weld formation of flat position welding is more stable and the U-rib weld penetration has been significantly improved. The optimum U-rib weld with penetration of 84.8% is achieved under the conditions of flat position welding with 285 A welding current, 44∘ torch angle, and 2[Formula: see text]mm distance between the wire and the root.

Experimental and numerical investigation on the impact response of bolt-ball joints

The densely populated space lattice structure requires reliable performance under impact loads. The bolt-ball joint serves a crucial role in connecting members at various angles, significantly contributing to the overall safety of the structure. However, there is limited literature available on the impact resistance of the bolt-ball joint. In this study, the drop hammer impact test system was employed to conduct impact tests on 11 specimens of bolt-ball joints. Comprehensive records were maintained, including the final deformation states, video recordings of the impact process, and data on impact force, displacement, and strain. Additionally, numerical simulation analysis was conducted to expand the scope of the study. Five failure modes were observed: global bending deformation, bolt fracture, local denting, coupling deformation of local denting and global bending deformation, bolt and tube fracture. When the impact applied at the bolt ball or conical head and steel tube welding positions, the impact process was categorized into three stages: inertia, global bending deformation, and elastic recovery/bolt fracture. When the impact position was the steel tube, coupling deformation and elastic recovery/ bolt and tube fracture were observed. The energy absorption during the impact test was analyzed, revealing a positive correlation between the degree of specimen failure and the proportion of energy absorbed relative to the work done by the impact force. The effects of impact velocity, impact position, bolt dimension and impact angle on the dynamic response of the specimens were thoroughly analyzed.

Active visual continuous seam tracking based on adaptive feature detection and particle filter tracking

Welding seam tracking based on online programming is the future trend of intelligent production. However, most of the existing image processing methods have certain limitations in the adaptability, accuracy, and robustness of weld feature point detection. The online welding method of gas metal arc welding (GMAW) based on active vision sensing is studied in this paper. The Steger sub-pixel detection method is used to guarantee the accuracy of feature point extraction, and a self-adaptive search window and self-adaptive slope extraction are proposed on this basis. The self-adaptive window is generated according to the linear information of the weld area, and the scale factor and range threshold constraint are added to realize the real-time detection of the weld feature information. Screening the center pixel of the laser stripe in the self-adaptive window of the current frame by the initial slope or the self-adaptive slope of the previous frame, the linear information of the weld area is obtained. The self-adaptive slope of the current frame is fitted by the random sampling consistency method, and the pixel margin is retained to adapt to the linear detection of different continuous welds. When arc light and other serious interference make it difficult to obtain weld information, a particle filter is used to make the best prediction of the weld position. Finally, the welding robot platform based on laser vision sensing was built to test various continuous welds of the butt weld, fillet weld, and lap weld. Experimental results show that the detection speed is 27 ms, and the accuracy of detection and tracking can respectively reach 0.03 mm and 0.78 mm, which meets the requirements of weld detection and tracking.

Porosity suppression of nickel-based superalloy by modulated base temperature in laser welding and mechanism analysis

This paper investigates the distribution pattern of welding porosity defects in annular weld seams of superalloy during laser welding. The results reveal that the initial portion of the annular weld seam exhibits a higher density and larger size of porosity defects compared to the ending portion. At a laser power of P = 360 W, the numerical simulation combination showed that the A1 region's average cooling rate is 8.767 × 103 °C/s and the A2 region is 8.151 × 103 °C/s that the thermal conduction effect at the initial welding position leads to an elevation in the base metal temperature in the subsequent unwelded region, thereby reducing the solidification rate of the molten pool in the latter half of the weld seam and effectively decreasing the porosity rate at the weld seam. Furthermore, the study demonstrates that elevating the base metal temperature can effectively modify the cooling rate of the molten pool, thereby influencing the formation of porosity defects. At a laser power of P = 360 W, increasing the base metal temperature to 600 °C reduces the cooling rate of the molten pool from 8.767 × 103 °C/s at a base metal temperature of T = 20 °C to 7.451 × 103 °C/s, leading to a decrease in the porosity rate from 3.357% to 0.022%. At a laser power of P = 672 W, increasing the base metal temperature to 600 °C reduces the cooling rate of the molten pool from 6.781 × 103 °C/s at a base metal temperature of T = 20 °C to 5.056 × 103 °C/s, leading to a decrease in the porosity rate from 8.214% to 0.002%. The increase in laser power brings more heat input, so the solidification rate of the molten pool decreases, but the porosity increases significantly. However, increasing the base temperature can effectively suppress the porosity defects under different laser powers. The research further reveals the relationship between welding porosity rate and cooling conditions, providing a control strategy for achieving low porosity rate welds.