Patent GB-811178-A (GB)
Title: A new or improved method of and apparatus for forming metal tubes
IPC: B21C37/10
Filed: 1955-12-07
Abstract: 811,178. Making tubes; angular bending; swaging; shearing. BLUEMEL BROS. Ltd. (Gerber, W.). Match 5, 1957 [Dec. 7, 1955], No. 35049/56. Classes 83 (2) and 83 (4). A method of forming a thin-walled tube from metal strip without welding or brazing comprises advancing metal strip, bending the strip progressively as it advances to substantially tubular form with the longitudinal edges of the strip in juxtaposed relationship, advancing the strip in tubular form over a mandrel of peripheral diameter corresponding to the desired bore of the tube, while simultaneously subjecting the exterior of the tubular strip to a hammering or swaging operation in such a manner as to bring the interior of the tubular strip into close engagement with the mandrel and at the same time to bring the opposed longitudinal edges of the tubular strip substantially into contact with one another throughout the entire length of the strip so as to form the tube, and subsequently severing the so-formed tube into predetermined lengths. Metal strip 17 is fed by driven rolls 18, off a reel 16, and through a series of freely rotatable forming rolls 19 mounted in a longitudinally adjustable support 20, which rolls progressively bend the strip into tubular form. Thence the tubular strip passes over a mandrel support rod 22 to swaging means which close the opposed longitudinal strip edges over a mandrel 21. The swaging means comprises, Figs. 2, 3, a sleeve 26 rotated about the mandrel 21, carrying a pair of tube closing hammers 28 slidable in opposed radial slots therein and driven inwardly by their contact with freely rotatable rollers 37 spaced around a fixed housing 23. The hammers 28 are grooved on their tube-engaging faces and chamfered at their entry ends. The so-formed tubing 27 then passes to tube cut-off mechanism 42 which includes a housing 43 mounted for longitudinal sliding movement of the machine. A block 44, rotated in the housing 43 by a pulley 48 carries three disc knives 45 in supports 51 slidable in radial grooves 52. The tubing 27 passes through a sleeve 65 axially slidable within a sleeve 62 fast with the block 44 until its forward end engages a pusher element 68 on an arm 69 pivoted to the housing 43. As the housing 43 is thus moved forward, a lever 78, pivoted thereto and engaging a grooved part 66 of the sleeve 65, is rocked, by the engagement of a member 80 on the lever with a fixed cam 82, to move the sleeve 65 back, relative to the sleeve 62, so that an externally tapered chuck 64 thereon closes to grip the tubing 27. A fixed cam 81 is then engaged by a member 79 (not shown) on a lever 59 pivoted to the housing 43 to rock the lever and axially retract a sleeve 57 in the block 44. This rocks levers 54 to move the knives 45 radially inwards to sever the tube. During such cutting operation, the arm 69 has moved up a cam slot 90 so that the pusher element 68 clears the forward end of the tubing 27 and the severed tube is allowed to drop into a shoot 91. On the members 79, 80 leaving the cams 81, 82 the chuck 64 opens and the knives 45 are moved outwardly and the housing 43 is returned by a weight 72a, the members'79, 80 being constructed as pawls swinging back as they pass over the cams. If the chuck 64 fails to disengage the tube the continued forward movement of the arm 69 rocks a lever 95 to operate a switch 97 to stop the machine. The plunger rods of cycle tyre pumps may be made by the apparatus. Specification 662,584, [Group XXIII], is referred to.