| 摘要 |
<p>Longitudinal corrugations are formed on a strip (12) of metal sheet by successive passages between counterposed corrugating barrels (20, 22) having alternated, circumferential ridges (24, 26) on their outer surfaces. The opposite, longitudinal lips (12a, 12b) of the strip (12) are bent in opposite directions, then the strip (12) of metal sheet is coiled into a helical shape, whereby the opposite, longitudinal lips (12a, 12b) overlap laterally. Before the opposite, longitudinal lips (12a, 12b) are crimped together between counterposed crimping rollers (38, 39), a rubber gasket (42) is fitted to one of the opposite longitudinal lips (12b). The gasket has a bent profile capable of embracing the longitudinal lip at least partially, whereby the material of the gasket (42), by effect of the crimping pressure, is reduced in thickness and deformed plastically at least in certain areas (12'a, 12"a, 12'b, 12"b) of the longitudinal lips (12a, 12b) which are biased against each other by the crimping action.</p> |
