Development of a robot for orbital welding

Abstract

Purpose -This work demonstrates the development of a robot, which was designed for the orbital welding of pipes. Design/methodology/approach -The robot consists of a small car pressed against the pipe by means of chains, which are used by the robot to move around it. To provide all necessary torch movements, the robot must have four degrees of freedom: torch travel speed, stick-out, torch angle and lateral motion. Thus, using a look-up table-which was specially designed to this application-it is possible to follow the optimal parameters (voltage, current, welding speed, torch angle and stick-out) for each welding position (flat, vertical and overhead). Findings -The robotization of the orbital welding process brings enhancement in the final product quality, considerable increase of repeatability, reduction of rework and reduction of the weld execution time. At the very least, the robot is capable to reproduce the weld bead of the best human welder, through the use of the same paramenters contained in a table. Practical implications -The use of this robot in welding with GMAW proved to be extremely viable. It was shown that the bead shape did not suffer great variations from one welding postion to another, thanks to the use of a gradual change of parameters. Originality/value -Although, by RIA definition the devices for the orbital welding shown in literature up to now are not robots, the developed device can be called a robot due to its capability of being completely programmable and automatically carrying through all welding activities.

A survey of platform designs for portable robotic welding in large scale structures

“…Lima II et al at the Universidade Federal de Minas Gerais, Brazil, [41] developed an orbital welding robot that is capable of moving around a pipe by the means of a pair of chains surrounding the pipe tightly ( fig. 11 right).…”

Closed-form solution for direct and inverse kinematic models of a parallel manipulator for robotic orbital welding

“…The proposal to create a robotic manipulator for orbital welding of metallic pipes in Lima II et al [9] was initially aimed at productivity: enhancement in the final product quality, increase in repeatability, reduction of rework and reduction of the weld execution time, in comparison with the traditional in-loco manual operations. The challenging aspect of these operations is that each welding bead is created using four different welding positions around the tube perimeter: flat, descendant vertical, overhead and ascendant vertical positions (Fig.…”

“…The initial concept of Lima et al [9] was a non-anthropomorphic serial robot with 4 degrees of freedom (DOF). The first DOF was provided by a car pressed against the pipe through chains, which were used by the robot to move around the pipe, making the translation movement, similar to tractor-on-track orbital welding system.…”

Human behaviour capturing in manual tungsten inert gas welding for intelligent automation

“…3 Most of the existing welding robots (such as spot welding robots) perform pre-programmed tasks in assembly lines which have less variation within the parts and the process. 4,5 Such operations do not require much intelligence and adaptability as the decisions can be pre-programmed. However, applications such as welding of aerospace components involve complex three-dimensional (3D) shaped components and require considerable real-time attention to any minor process variation.…”