In-Process Radiography of ARC Weld

In-process nondestructive evaluation of welds is of major importance for automated weld processing. Real-time evaluation of defect formation makes possible on-line rewelding and adjustment of process parameters. Measurements of physical parameters related to weld quality may also give information important for understanding the weld process and for improvements of weld quality. In this study we implement industrial radiography for real-time weld process monitoring and testing. X-ray penetrating radiation is used for volume observation in the welding pool and the heat-affected zone during the weld process. The advantages of such a technique are on-line testing of defect formation in the weld and the study of metal fusion and filler metal-base metal interaction, metal transfer and mass flow in the welding pool. This technique may also be used for post-service real-time remote testing of weld quality. By integrating automatic nondestructive inspection with an automatic process control system, unified manufacturing control and testing procedures can be developed. In this unit approach, the nondestructive system may be included as a part of the sensing system in the feedback loop of the process control. Research and development of such general concepts for remote weld process control using real-time radiography as a vision system was initiated in our laboratory under the sponsorship of the Edison Welding Institute

Система мониторинга для трубосварочного стана

Разработана система мониторинга и контроля сварочного процесса для трубосварочного стана, состоящая из трех подсистем: контроля проплавления с обратной стороны сварочной ванны, контроля формирования сварного шва трубы и слежения за стыком. Рассмотрены построение этих подсистем с использованием системы технического зрения, а также аппаратные и алгоритмические методы минимизации влияния оптических (блики, засветка от сварочной дуги) и механических (царапины, ржавчина, заусенцы) помех. Созданная система обеспечивает высокую точность измерений в режиме реального времени.Welding process monitoring and control system for a pipe welding mill has been developed. The system consists of three subsystems, namely for control of penetration from the reverse side of the weld pool, control of the pipe weld formation and weld following. Design of these subsystems using a technical vision system, as well as hardware and algorithmic methods for minimizing the effect of optical (blinks and flashes due to the welding arc) and mechanical (scratches, rust, burrs) interferences, are considered. The system provides high real-time measurement accuracy

Development of a vision system for TIG welding - a work-in-progress study

The development of a Vision System for TIG Welding has the potential to help realize a real time process monitoring system for joining tasks which require automated welding. A key application of this technique is in the Nuclear Industry; where industrial components require several passes (layers of welding) to achieve robust joints. Through monitoring a welding process such as this in real time, material and time waste could be drastically reduced as faults could be instantly identified. A TIG welding arc is a very intense source of both light and heat, making the creation of a vision system for it challenging. Higher currents result in; brighter TIG welding arcs, higher energy input and deeper and wider weld pools. Nuclear industry applications require deep penetration welding but bright TIG welding arcs can overwhelm the intensity of an auxiliary illumination laser reducing the image clarity of an observing camera system. Thus, a balance between a wide weld bead with clear features applicable to deep penetration but without a brightness level which overwhelms that of the laser must be found. This paper is a Work-in-Progress study of a vision system for TIG welding using an automated TIG welding system and a camera with a laser illumination system. Welding was performed using a Miller Dynasty 350 at 100A with a 3B class laser used to illuminate the weld pool

Vision-aided Monitoring and Control of Thermal Spray, Spray Forming, and Welding Processes

Vision is one of the most powerful forms of non-contact sensing for monitoring and control of manufacturing processes. However, processes involving an arc plasma or flame such as welding or thermal spraying pose particularly challenging problems to conventional vision sensing and processing techniques. The arc or plasma is not typically limited to a single spectral region and thus cannot be easily filtered out optically. This paper presents an innovative vision sensing system that uses intense stroboscopic illumination to overpower the arc light and produce a video image that is free of arc light or glare and dedicated image processing and analysis schemes that can enhance the video images or extract features of interest and produce quantitative process measures which can be used for process monitoring and control. Results of two SBIR programs sponsored by NASA and DOE and focusing on the application of this innovative vision sensing and processing technology to thermal spraying and welding process monitoring and control are discussed

In-Line Monitoring of Laser Welding Using a Smart Vision System

This paper presents a vision system for the in-line monitoring of laser welding. The system is based on a coaxial optical setup purposely chosen to guarantee robust detection of the joints and optimal acquisition of the melt pool region. Two procedures have been developed: The former focuses on keeping the laser head locked to the joint during the welding; the latter monitors the appearance of the keyhole region. The system feedbacks the joint position to the robot used to move the welding laser and monitors the penetration state of the laser. The goal is to achieve a continuous adaptation of the laser parameters (power., speed and focusing) to guarantee the weld quality. The developed algorithms have been designed to optimize the system performance in terms of the elaboration time and of accuracy and robustness of the detection. The overall architecture follows the Industrial Internet of Things approach, where vision is embedded, edge-based analysis is carried out, actuators are directly driven by the vision system, a latency-free transmission architecture allows interconnection as well as the possibility to remotely control multiple delocalized units

Welding torch with arc light reflector

A welding torch arc light reflector is disclosed for welding torches having optical viewing systems. A schematic of a welding torch having an internal coaxial viewing system consisting of a lens which focuses the field of view of the weld scene of the workpiece onto the end of the fiberoptic bundle is provided. The transmitted image of the fiberoptic bundle is provided to a camera lens which focuses it onto a TV sensor array for transmission. To improve the parity of the image of the monitoring system, an arc light reflector is shown fitted to the end of the torch housing or gas cup. The arc light reflector has an internal conical section portion which is polished to serve as a mirror which reflects the bright arc light back onto the darker areas of the weld area and thereby provides a more detailed image for the monitoring system. The novelty of the invention lies in the use of an arc light reflector on welding torches having optical viewing systems

Self-clamping arc light reflector for welding torch

This invention is directed to a coaxial extending metal mirror reflector attached to the electrode housing or gas cup on a welding torch. An electric welding torch with an internal viewing system for robotic welding is provded with an annular arc light reflector to reflect light from the arc back onto the workpiece. The reflector has a vertical split or gap in its surrounding wall to permit the adjacent wall ends forming the split to be sprung open slightly to permit the reflector to be removed or slipped onto the torch housing or gas cup. The upper opening of the reflector is slightly smaller than the torch housing or gas cup and therefore, when placed on the torch housing or gas cup has that springiness to cause it to clamp tightly on the housing or gas cup. The split or gap also serves to permit the feed of weld wire through to the weld area

Task analysis of discrete and continuous skills: a dual methodology approach to human skills capture for automation

There is a growing requirement within the field of intelligent automation for a formal methodology to capture and classify explicit and tacit skills deployed by operators during complex task performance. This paper describes the development of a dual methodology approach which recognises the inherent differences between continuous tasks and discrete tasks and which proposes separate methodologies for each. Both methodologies emphasise capturing operators’ physical, perceptual, and cognitive skills, however, they fundamentally differ in their approach. The continuous task analysis recognises the non-arbitrary nature of operation ordering and that identifying suitable cues for subtask is a vital component of the skill. Discrete task analysis is a more traditional, chronologically ordered methodology and is intended to increase the resolution of skill classification and be practical for assessing complex tasks involving multiple unique subtasks through the use of taxonomy of generic actions for physical, perceptual, and cognitive actions

Process Control of 3D Welding as a Droplet-Based Rapid Prototyping Technique

Three-dimensional welding is investigated as a rapid prototyping technique for the production of real Inetallic parts using gas metal arc welding principles. A high speed machine vision system is used to study the correlation between droplet transfer parameters and resultant weld penetration characteristics. Experimental work is conducted to determine how droplet transfer frequency, droplet size, and number of passes affect the geometrical and Inetallurgical properties ofthe weld penetration. A finite element analysis is performed in order to study what influence additional layering has on the cooling characteristics and resultant penetration profile.Mechanical Engineerin

Simultaneous in-process control of weld pool geometry and heat affected zone based on thermal- optic imaging for welding of steel materials by concentrated energy fluxes

Abstract Robot welding using high power energy flow processes is widely used in the fabrication industry for increasing productivity and enhancing product quality. The application of infrared thermography to the adaptive control of different welding processes is discussed in this paper. Because these processes are difficult to control and automate, the quality of the product can vary over a large range. Therefore temperature gradients need to be controlled directly on-line with a high accuracy. This requires twodimensional temperature monitoring. A thermo-optic camera system can be used in order to investigate the cooling process in the weld seam area as well as in the heat affected zone. It was found that reasonable correlations exist between thermo-optical machine vision and weld seam quality, as far as weld pool geometry and thermal cycle interrogation is concerned