DESIGN AND CONSTRUCTION OF ARC WELDING MACHINE

ABSTRACT

This project is titled the designing and construction of an electric A.C arc welding machine. Arc Welding Machine of 220 Volts and output voltage of 25 volts. A core type step-down transformer and choke are essential as the voltage or the arc is usually between 50 and 100volts. The choke is necessary to displace the phase relationship of the voltage and current so that the heat of the arc may be maintained by ensuring that zero points of current and voltage are as far apart as possible. This welding machine is able to deliver a current 30Amps at voltage of 220 volts, the transformer is mounted on a rectangular metal frame and its enclosed by a case which has opening at a regular internal order to provide air for the cooling of the transformer. A double insulation technique is employed for better protection from electric shock and short circuit in the machine or when working in moist environment. An all-purpose electrode holder is connected across one or the output terminal of the transformer so that various size of electrode can be held properly. After the transformer had been constructed, the primary terminals were connected to source of supply. Then the secondary terminal was connected to the welding circuit, as a source of supply, with the aid of welding cable, by which one of the terminal was connected to the ground clamp and the other to the electrode holder. A.C. Electric Arc Welding Machine uses alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, and/or slag. The aim of this work is to design and construct an electric welding arc that can be used to weld metals.