GB1191797A - Method of Reforming Tubular Metal Blanks into Inner-Fin Tubes - Google Patents

Abstract

1,191,797. Swaging; making finned tubes; boring bars. VALLEY METALLURGICAL PROCESSING CO. 15 July, 1968, No. 33709/68. Headings B3A, B3C and B3H. An internally finned heat-exchange tube is formed from a metal tubular blank t by feeding it over a grooved mandrel 68 between the dies of a rotary swager 30. The swager has a pair of opposed dies 50 moved inwards by hammer blocks 52 as the spindle 34 on which the dies are slidably mounted is rotated. The pass between the dies is tapered so that the fin forming into the grooves of the mandrel is progressive. The swaging may completely fill the mandrel grooves 70 with metal. The mandrel 68 is fixed at its rear end to a bracket 74 by nuts 80 which allow rotation thereof. The tube is moved through the swager by a feeding block 86 which abuts the rear of the tube. The block is driven by a motor or by a handle 96. The blank is placed on the mandrel when it is removed from the bracket 74 and the block 86 has a slot to receive the mandrel. The end of the blank is preferably pushed through the swager by the next blank fed by the block. The tube may have one or more longitudinal, or helical fins formed on its inner face. The fins may be formed on one side of the bore, Fig. 14 (not shown), and part of the fins may be removed by a reciprocating cutter (156), Fig. 15 (not shown). The cutter blades (158) are adjustable so as to progressively remove parts of the fins on each pass. The formed tube may be drawn to smooth its outer surface, Fig. 16 (not shown). The cross-section of the tube may be altered by subsequent drawing or rolling, preferably immediately after swaging. The reduction in cross-sectioned area produced by the swaging is within the range substantially 1-6: 1 to 3: 1 and preferably within the range 2: 1 to 3: 1 for complete filling of the grooves with the metal displaced from the blank wall.