Patent GB-343453-A (GB)
Title: Improvements in and relating to the manufacture of tubes and particularly tubes for heat transference devices
IPC: B21C37/26
Filed: 1930-04-22
Abstract: 343,453. Making tubes. STILL, W. J., 19, Denbigh Road, West Ealing, London. April 22, 1930, No. 18747/29. [Classes 83 (ii) and 83 (iv).] Angular bending; coiling; corrugating; bending formers; drawing; punching; soldering.-Metal tubes, particularly for heat transference purposes, are made by progressively bending a sheet metal strip while passing over rollers and over a mandrel so as to form a longitudinally butted or overlapped tube, preferably of flat or oval section or with flat sides slightly curved outwards, rotating the tube to wind helically thereon a radiation fin and uniting the edges of the tube by soldering, bending &c. and the fin to the tube. The tube strip, which may consist of noncorrosive metal such as copper or brass and may be turned on one side, is mounted on a drum D, Fig. 4, carried by a member 1 rotated by spur gear 15 and bevel gear from the driving shaft. The strip is drawn by a pair of belts B<1> through a rubber roller 41 and a metal roller 42 held together by a spring 42<a>, thence through a die h for flanging its edges and thence over a series of rolls R<1> on which it is bent by the belts. The belts pass over a series of rollers 59, 58, 24, the axes of which from one end to the other are gradually inclined through 90‹ so as to bring the strip to tubular form. The belts are driven through worm gear 21, 22, Fig. 5, and spur gear carried by the member 1 and engaging a fixed internally toothed circular rack 4. A second pair of narrow belts passing over rollers beneath the rollers 58, 59 and geared thereto, ensure a grip on the strip so as to effect a regular movement. The strip, during bending, passes under rollers 31 and then on to a flat-sided or other mandrel M under rollers 37, 38 where the bend is completed by folding over the lower edges by a die 54<c>, Fig. 6a, carried by a spring-pressed lever 54<d>, a roll 36 carried by a spring-pressed arm 36<a> and rollers 37<a>. The feed of a new strip is first effected by rotating the worm 21 by ratchet mechanism 29, 39. The roller 36 and die 54<a> may be freed from the strip by operating handles 54, 54<a>. The fin strip, which may be of iron and preferably tinned, is wound on the tube T, Fig. 12, by rotation of the mandrel, and may first pass in contact with a grinder, flux container and tinning bath. It may be formed of angular cross-section with corrugated webs S separated by gaps at the edges of the tube by drawing through a pair of corrugating dies e<1>, e<2>, Fig. 2, thence through punches e<5> for forming slots in the vicinity of the parts of the web which are to engage the edges of the mandrel and thence through a groove in an angle-piece on the bracket e<16>, over which the strip is flanged by a lever f<1>. The edges of the flanges of consecutive windings may be abutted in winding, in which case they also are previously tinned. The die e<2> and punch e<5> are carried by a slide e<3> operated by eccentrics on a shaft 3<b>, which is rotated by a chain at twice the speed of the mandrel. The lever f<1> is operated by a cam 3<a> on the shaft 3<b>. The dies &c. are operative when the mandrel is almost in line with the. strip and to compensate for any movement of the strip during this period, the parts are carried by a member e<8> mounted on adjustable rods p<1> s) that it is moved by the strip in bearings p<2>. The member e<8> is returned after operation by a spring e<9> against an adjustable stop e<80>. The finned tube then moves through passages of the same size in the rotary portion 48 of a muffle heated by a gas burner so as to melt the solder. The rotary portion is driven by spur gear from the same shaft as the member 1. The hot gases pass from the chamber 53 through an opening into the rotary portion and then pass into the chamber 49 and out to an induced draught and on through an exhaust port. The temperature may be controlled by a thermostatic regulator operating the gas valve. Air is also drawn in at the other end of the muffle through chamber 48 and passes through the exhaust port so as to cool the solder. The tubes are then cut into lengths by saws &c. The fin may be soldered by feeding a rod of solder to the tube and melting it as the joint advances or the heating may be deferred until the fin and solder wire have been bound on the tube. Cooling may be effected by a water spray instead of air.