Patent GB-869021-A (GB)
Title: Improvements in or relating to the production of tubular bodies
IPC: B21C37/12
Filed: 1958-01-13
Abstract: 869,021. Making tubes; coiling welding by-fusion; rolling. ECKHARDT, W. Jan. 13, 1958 [Jan. 15, 1957; Aug. 13, 1957], No. 1204/58. Classes 83 (2) and 83 (4). A tube is formed by feeding strip to the inner curved surface of a hollow shaping tool of substantially semi-circular crosssection to coil it helically into tubular form and welding together the adjacent edges of the coiled strip. Strip 1 is fed between one or more pairs of rollers 10 and pairs of edge rollers 11, 12, the distance between the rollers 11, 12 of each pair diminishing slightly towards a coiling tool 2, the pair 11, 12 nearest the tool being a distance apart equal to the smallest permissible width of the strip 1, the strip being of slightly non-uniform width. The rollers 11, 12 thus serve to upset the edges of the strip so that the strip is of constant width as it is fed into the tool 2. The strip 1 is fed over a ribbed guide plate 9 to the tool 2 by driven rollers 15, 15<SP>1</SP>, the upper being loaded by a weight towards the lower. The tool 2, which is in the form of a semicylindrical shell, is secured on a turntable 19 and makes an angle with respect to the advancing strip such that the strip is helically coiled by its engagement with the inner surface of the tool to form a tube 3, which, if the angle is varied during coiling, may be of conical form. The abutting edges of the coiled strip are welded together, at least tack welded, so that the tube 3 leaving the tool 2 is rigid and may be supported by a pair of balls 23 on a slide rest 25 on a turntable 27 adjustable along a frame 30. Such adjustment may be effected by a motor 28, during the coiling operation and while the tube 3 is supported by the balls 23 so that the edges of the coiled strip may be kept pressed together for welding. This adjustment may be effected under the control of microswitches operating the motor 28 in accordance with the width of the strip 1 as it enters the tool 2. Alternatively the slide rest 25 may merely be spring-urged. A table 32 is carried by the slide rest 25 to extend alongside the tube and has slidably mounted thereon a carriage 33 carrying a saw 37 and supporting one or more rubber rollers 34 movable into engagement with the tube 3 so that the carriage 33 moves longitudinally with it and the saw cuts a length of tubing off. The strip 1 is preferably fed to the tool 2 at such an angle that the radius of the tube is less than that of the inner surface of the tool 2. In order that the strip edges may be properly welded together the rollers 11, 12 may form a groove 43, Fig. 7, on one edge of the strip into which the other edge is inserted during coiling. The rollers 11, 12 may alternatively form a tongue 53, Fig. 11, at one edge of the strip and a groove 52 at the other. In this case one roll comprises a grooved member 90, Fig. 16, carried by an annular member 85 rotatable around a shaft 82 carried by a slide 75 adjustable by screw means 76, and the other roll has a ridged member. A ring 89, which may be of abrasive material, carried by the annular member 85 cooperates with a similar ring 91 on an annular member 86 urged downwards by springs 87 to remove scale on the edge of the strip. The other roll is likewise provided with scale removing rings. The rings and rolls may be of a shape to guide superposed strips which overlap laterally and whose edges may be tongued and grooved. An I-sectioned strip 46, Fig. 8, may be used to connect the edges of the coiled strip 1, being fitted on one edge of the strip while it is being fed to the tool 2. The I-strip 46 may have a rib 49, which will project from the outer surface of the formed tube and be secured to the coiled strip 1 by a weld 50. The I-strip 46 may also have a rib which will project from the inner surface of the formed tube and each rib may be provided with a weld at both sides thereof. When the strip 1 is tongued and grooved it may be welded together at its edges by an inner weld 73, Fig. 15, and have an outer weld 72 of greater thickness than the weld 73. The tube may be formed from superposed laterally overlapping strips 54, 55, Fig. 13, one of which may be preheated, secured by welds 60, 63, or from overlapping strips 64, 65, 66, Fig. 14, each preheated to a different temperature, some of the edges of which may be rounded off to facilitate interengagement, secured by welds 70, 71 intersecting one another. The internal welding is effected before the coiled strip 1 has passed beyond tool 2.