A literature review on welding certificate for robotized welding
The higher production of more and more complex products challenges the accurately for manual welding, and increase the time it takes to programme automatic welding systems. The main objective for the article is to see if current regulations and standards are able to accommodate the shift from automatic weld to autonomous welding systems. To do this, the most current and applicable standards have been analysed. Where there is a need for human input I have tried to find research in new systems that is able to assist computer systems in obtaining that information. The findings are that most of the current standards have room to accommodate autonomous systems, given that the correct safety precautions are taken.
Automatic ultrasonic robotic array
A novel, autonomous reconfigurable ultrasonic phased array inspection robot for non-destructive evaluation (NDE) is presented. The robotic system significantly will reduce manual labor over current inspection regimes, as well as enabling inspection of inaccessible/hazardous areas such as those found in the nuclear and petrochemical industries. It will offer three quantitative benefits: improved inspection accuracy, improved safety and reduced inspection costs. The current major innovation is in embedding ultrasonic phased array technology into a small form-factor robotic vehicle, overcoming issues in ultrasonic coupling, miniaturized electronics and robot positioning. This paper presents an overview of the robot specification and system architecture along with details of a specific inspection scenario where the robot is required to inspect a saddle weld found in reheat bifurcation. This weld is formed from the intersection of two 60 mm thick steel pipes with diameters 500 and 300 mm. The robot will be capable of tracking the weld from either pipe, projecting an ultrasonic beam normal to the direction of travel. The design of a 2 MHz, 16 element embedded phased array controller is presented. A timing model of the controller details the throughput required to enable the robot to perform ultrasonic inspection while tracking the weld at 20 mm/s. The paper also considers robot positional estimation. The nature of the inspection prohibits the use of external positioning systems so the system is limited to on-board sensors, namely wheels encoders, a six axis inertial sensor and a surface feature tracking camera. The results section focuses on the characterization of inspection performance, driven in part by the ultrasonic phased array controller and robot positional estimation. A-Scans are presented to show the SNR of each array channel which was approximately 24 dB when measuring the back wall echo. It is shown that ultrasonic scan rate is limited by 802.11g wireless transmission from the robot to the host computer.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.