Abstract:
Welding of pipes and tubes is employed in practically every engineering application. In
Amhara Metal Industry and Machine Technology Development Enterprise (AMIMTDE) pipes,
pressure vessels, and any cylindrical components are welded manually which is slower and
vulnerable to human error, resulting in non-uniform, less-quality, and inconsistent weldments.
This study developed an automated orbital pipe welding system, that automatically holds and
moves the welding gun at constant speed on a circular rail fixed near the pipe joint after
adjusting its arc length automatically to overcome the problems in AMIMTDE. After the
development, this study optimized the welding process parameters (i.e welding current, arc
voltage, welding speed, and arc length) of the automated orbital MIG welding process on
welding AISI 1020 mild steel grade pipe by demonstrating the impact of various input
parameter levels on the tensile strength and hardness of the welded joint. Three levels of
variation were applied to the four input parameters that were chosen. Nine experiments were
carried out using Taguchi's L9 orthogonal array approach. For modeling the orbital pipe MIG
welding process experimental input parameters and response results, an Artificial Neural
Network (ANN) was constructed. During modeling the results indicated that, a 4-9-2 network
trained by Bayesian Regularization (BR) approach was determined to have the greatest
prediction capability, with a mean squared error (MSE) of 5.06e-05. Then this model was taken
to the genetic algorithm (GA) to determine the combination of optimal process parameters that
yields maximum hardness and tensile strength. The feasible optimal process parameter of a
combined artificial neural network and a genetic algorithm (ANN-GA) was identified as
welding current 94.14143 A, welding voltage 23.98961 V, welding speed 31.84924 cm/min,
and arclength 2.766681 mm resulting in maximum tensile strength and hardness of 417.857
MPa and 96.5364 HR respectively. Finally, a confirmation test was conducted with the
optimum parameters. The predicted and confirmation test results percentage error was 1.23 %
for tensile strength and 1.59 % for hardness. Thus, it has been concluded that the confirmation
experimental results are within the acceptable range of percentage error as per the reviewed
literature.
Keywords: Orbital pipe welding, ANN, GA, process parameters optimization, Tensile strength.