GB1103113A - Improvements in and relating to the manufacture of corrugated metal tubes or bellows - Google Patents

Abstract

1,103,113. Corrugating tubes. J. H. MILLAR. 8 Sept., 1964 [12 Sept., 1963], No. 36032/63. Headings B3A, B3E and B3Q. A method of corrugating a metal tube 4 comprises surrounding the tube with two dies 6, 8 having an internal recess 16, 20 of the same width, when closed, as the desired corrugation, expanding the tube in the die-recess by internal pressure to form a corrugation, releasing the internal pressure somewhat, withdrawing the die 8 longitudinally and then forcibly re-closing or " kicking " the die 8 against die 6 to set the corrugation to its final form. The internal pressure may be applied hydraulically or, as shown, by a plug 36 of rubber compressed against the end of a mandrel 2 by a member 38 drawn endwise by a rod 42 passing through the mandrel. In a preliminary operation, Fig. 2, die 8 is adjusted endwise by an hydraulic motor 22 above or below the dies and a lever 26 to space the co-operating parts 16, 20 of the recess formed in the end of die 8 and in an internal shoulder in die 6. In this position the rod 42 is operated by an hydraulic motor 40 to expand the tube. The die 8 is then moved endwise into engagement with the shoulder in die 12 and the plug further compressed to form the corrugation. Reduction of the compressive force on the plug 36 follows and withdrawal of the die 8, allowing the corrugation to spring back. The die 8 is then struck back against the shoulder in die 12 to set the corrugation. Stops (not shown) for the rod 42 correspond to full and partial compression of plug 36. Sectional dies; feeds.-Die 12 is in two sections which may be separated by a motor operating a toggle linkage or, as shown, by a pair of hydraulic motors 18. The dies are then moved along the tube by an hydraulic motor 32 and a toggle mechanism (not shown) before being re-engaged with the tube, the last corrugation entering a recess 14 in die 12. Return movement of the dies by motor 32 feeds the tube along the mandrel 2 by an amount equal to the pitch of the corrugations.