GB740518A - Heat exchanger and method and apparatus for making the same - Google Patents

Abstract

740,518. Making heat exchangers. AKTIE-BOLAGET SVENSKA MASKINVERKEN. Nov. 4, 1953 [Nov. 10, 1952], No. 30517/53. Classes 83 (2) and 83 (4). [Also in Group XIII] Electric welding; soldering; bending.-A method of making a heat exchanger comprising a base wall provided with surface extending elements in the shape of pins or wires is characterized in that the elements are simultaneously welded or soldered groupwise with two or more elements in each group in such a manner that all elements within each group are contiguous to one another at the base wall to which they are secured in a common solid joint which is independent of the joints between the other groups and the base wall. Lengths of wire stock 19 carried on reels 10 are fed by driven rollers 11 through a guide 12 and thence to a chuck 13 in which the wires are held. The chuck is moved laterally and the lengths of wires 2 held in the chuck are sheared from the stock. The chuck engages with a ram 14 which advances towards the clamped heatexchanger tube 1 and the wires 2 are forced against the tube and resistance welded as disclosed in Specification 673,721. The chuck may be cooled by fluid circulated therethrough to prevent adhesion of the wires to the chuck. The ram carries a tapered fluted mandrel 15 which engages the group of wires already welded to the tube and bends them to diverge as shown in Fig. 1. Alternatively, the mandrel may be omitted and the wires bent intermediate their ends as in Fig. 2 by rotating the tube 1 until the wires engage a fixed bar. After welding, and preferably when the chuck is being reloaded, the tube 1 is fed axially a distance equal to the distance between the mandrel and the chuck in readiness for the next welding operation. When a row of wire groups have been welded the tube is rotated the required amount to enable the next row to be welded. The groups of wires may be welded to a plane metal sheet if desired. In a modification precut wires 26, Fig. 9, contained in a hopper 25, are intermittently advanced in groups into the chuck 29, 30 by a feeding device 27 and guide 28 in timed relationship with the reciprocation of the chuck. Alternatively, the wire may be soldered by providing the wires or the base wall with a coating of tin or solder and heating the wire groups when pressing them against the base wall and finally cooling the wires or wall to form the joint. Specification 675,604 also is referred to.