The use of pulsed current to control the weld profile and metal transfer in the submerged arc welding process
The main objectives of this study are:-
1 - to construct a wiring connecting system between the
pulsed and direct current units to produce a pulsed
submerged arc weld.
2 - to determine the boundary conditions for the welding
parameters used to control weld profile and metal
transfer during pulsed current submerged arc welding.
3 - to establish a relationship between the pulsed
current frequency and the geometry of the deposited
weld metal, and to apply the results to narrow gap
4 - to design and construct a microprocessor interface
system capable of handling, presenting and storing
The thesis has been divided into three parts as follows:-
Part I The feasibility of pulsed current submerged
arc welding process.
Part II The use of pulsed current to control the
geometry and properties of welding metal.
Part III Computer aided monitoring of the welding
In the first part, a review of relevant information is presented
together with a description of the experimental technique used
in connecting the pulsed and background current units.
In the second part attention is focus sed on the procedure for
identifying the usable zones within which a successful weld can
be obtained. Critical boundary conditions of welding parameters
were established using the combination of pulsed and direct
currents. Having established these boundaries, the effects
of pulsed current frequency on the weld profile and weld metal
properties were investigated and the results used to establish
a practical guide line on narrow gap applications.
In the third part the design and construction of a microprocessor-
based system was designed to monitor the welding
parameters using binary counter, an analogue switch and voltage
to frequency converters which enables real time values of welding
variables to be determined over a period of between 1 - 100
seconds, depending on the memory size of the microprocessor.