In testing temperature rise of A. C. arc welder, it has been conventionally accepted to load the welder with fall load current, with secondary terminals being directly short circuited. Under this condition, the position of moving core or moving coil, as the case may be, is different from their normal full load working position, in which case secondary terminal voltage is not zero, but is the sum of arc voltage and voltage drop along the welding cable. Difference of position of moving core or coil causes diffence in distribution of leakage flux, which in turn results difference in stray load loss, and also it may cause difference in ventilating effect of the winding. These effects, individually or combined, will ultimately affect the temperature rise of the winding. In this respect it is desirable to load welders with secondary resistance, that gives the secondary terminal voltage of same r. m. s. value as actual arc voltage, but this is rather infeasible from the practical point of view. In this paper we propose to replace the secondary load resistance with reactor, and the effect is fully discussed. In this case moving core or coil is pre-adjusted to the position at which rated full load current can be delivered at rated primary voltage and at rated secondary output voltage of narmally loaded condition, and the secondary current is adjusted to rated full load value by changing the reactance or impedance connected to the secondary terminals. By doing so, we can reproduce the same ventilating condition, together with same copper loss and stray load as normal full load condition. But, secondary terminal voltage becomes somewhat lower, and flux interlinking with the secondary winding becomes correspondingly lower, than resistance loaded condition. (Fig. 5) Iron loss of arc welder is, however, usually small as compared to the sum of copper loss and stray load loss, therfore small difference of the core loss due to the above mentioned slight. change of flux density of the core just below the secondary winding, can be neglected, and we can get almost same result of temperature rise. Necessary secondary load reactance can be obtained easily by making loop or coil of several turns with secondary lead wire, and its reactance value can be adjusted by changing the shape of coil or its number of turns.
The arc welded properties of killed steel plates containing 0.02-0.12 per cent of titanium have been examined. In the manual welding of Vee joints of the plates 12 mm in thickness, the hardnesses of areas of mother plates adjacent to the weld metals were almost the same, however the impact values of the welded titanium steel plate at room temperature and at 0°C were excellent compared with the rimming steel of the same thickness or the killed steel, which contained no titanium. The high speed automatic arc welding of the square butt joints of these plates was carried out under the conditions in which the weld crack was easy to happen. No cracks occurred in the titanium steel and good impact values were obtained in deposit metal and second part as compared with other kinds of steels provided in this experiment.
By measuring the deformations due to welding & removing of the externai restraint respectively in each member of the special H-form test specimen which is kept under external restraint, the author determined the magnitude of the welding residual stress in these members, and then performed tension tests on the small test specimens made of each member of the large one above mentioned. Finally, resulting from repeated tensile static load. the strength & deformation of two different kinds of the H-form test specimen (AB & SS 41 Steel) were measured. From these measured results. the author investigated experimentally the effects of the welding residual stress due to the external restraint upon the strength & deformation of the steel structure. It was cleared that those effects depend upon the mechanical properties of materials.