Study on Tube-Expanding by Drawing of Phosphor Deoxidized Copper Tubes : Fourth Report : Relations between Contact Length and Dimensional Accuracy

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The "tube-expanding" has been known mainly as expanding tube-ends for fixing them on the boiler-plate, using a special end-expander. The process, however, is neither applicable for expanding a tube uniformly along its total length nor applying it for manufacturing composite tube of any kind and no papers reported for such purposes have been found in the literatures. The authors have, so far, reported the results of the "Expand-Drawing", in which a specially prepared plug was inserted in a to-be drawn tube, the former being screwed at the front end of an externally fixed mandrel-rod; the tube was drawn thus over the plug expanding it diametrically. The results of the preceding experiments have been indicating the probability of the configuration-dependence of the plug on the wallthickness scatters of expanded tubes. The results of the new experiments with varying plug-tapers have been as follows. (1) In 15% expanding, with plugs of 6,13 and 20° in taper, the expanding procedure was stabler and the observed circumferential wallthickness scatters were less than those when 30 and 45° were used (no axial scatters observed, however, between the two). (2) In 5% expanding, the circumferential scatters were conspicuously increased other than by 6° in taper. (3) For expanding the tube without lowering the original thickness accuracy of the tube, the ratio of plug contact-length to tube inside-dia. should be kept more than 0.2.
東海大学の論文