US1998552A - Manufacture of gilled tubes - Google Patents

Description

April 23, 1935.

R. MAUTSCH MANUFACTURE OF GILLED TUBES Filed April 8, 1935 Patented Apr. 23, 1935 1,998,552.

UNITED STATES PATENT OFFICE 1,998,552 MANUFACTURE OF GILLED TUBES Robert Mautsch, Brussels, Belgium, assignor to Manufacture Generale Metallurgique, Societe Anonyme, Brussels, Belgium, a Belgian com- Application April 8, 1933, Serial No. 665,203 In Belgium April 12, 1932 3 Claims. (01. 113-118) This invention relates to the manufacture of creasing the surface available for heat exchange. gilled tubes of the type used, more particularly, To expand the tubes, I may use any suitable in heat exchange apparatuses. It is well-known means, as hydraulic pressure, or a mandrel either that the efliciency of heat-exchange apparatuses rigid or expansible.-

5 comprising gilled tubes or pipes is largely de- My improved process insures permanent and 5 pendent upon the closeness of the contact beintimate contact between the tube and the gills, tween said tubes and the gills mounted thereupon, the latter acting as powerful springs and being which may be secured in position by various permanently under elastic tension. It is parmeans, as by expanding said tubes, or by welding, ticularly suitable for securing gills on thin for example. It has been proposed to improve walled tubes. I 10 the contact between tubes and gills by combining Gilled tubes according to my invention and a the two said methods, or by providing the gills process for producing the same are illustrated, with collars adapted to enclose a larger area of by way of example, in the accompanying drawsaid tubes, or again by corrugating or puckering ing whereof:

said gills. These various methods however can Fig. 1 is a diagrammatic view of a gilled tube 15 not be entirely relied upon to ensure strength in provided with swellings according to the inventhe assembled unit, the ability of the same to tion;

' withstand long use, or uniform contact between Fig. 2 shows said tube at one stage of its progills and tubes at all points of the latters peduction; I

riphery. Fig. 3 illustrates an alternative method for 20 The object of my invention is to provide tubes forming a e according to the invention; having gills firmly secured thereupon, in close Fig. 4 shows a tube provided with puckered contact therewith, by deforming the metal .of gills.

= said tubes and making use of the resiliency of n t e Variou figures of the drawing, the tube the metal of said gills, under conditions calg n r lly designated y a is provi wi h a plu- 25 culated to ensure therebetween a contact adapted a ity 0 gills designated by Con 0f highly to remain permanent despite oxidation and other resilient metal, said gills being mounted upon phenomena concomitant with the ageing of astube a which is thereupon subjected to internal sembled units. pressure as, for example, by having inserted In accordance with my invention I obtain thereinto a mandrel c whereof the diameter is 30 this result by making the gills of a metal the greater than the outer diameter of said tube. resiliency or the hardness of which has been Upon being moved in the direction indicated by increased, by a mechanical or by a'thermic treatthe arrow (Fig. 2), the mandrel firstly expands ment for example, to such a degree that it is subthe tube at a. W n Passin through the Plane stantially greater than that of the-metal formof the first gill, the mandrel likewise expands 35 ing the tubes, and by causing the expansion of said gill by elastic deformation. After the man,- the tube to tension the metal of the gills sufdrel has passed beyond the gill (position shown ficiently to ensure that, on contracting after rein Fig. 2) the considerable resilient energy stored lease of the pressure applied for expanding the therein is released, and the gill contracts to grip 40 tube, each gill forms a constriction in the tube the tube, while a swelling d is formed between 40 The metal forming the tubes may be rendered said gill and the next in succession. Upon havingductile, for example by an annealing treatment; been thus distorted, the gill possesses suflicient in order to accentuate as much as possible the stored resilient energy to cause it to exert upon difference between the resiliency of the gills and the tube a degree of pressure which is all the the lesser resiliency of the tubes- When the greater that the expansion of the latter has been 45 metal of the tubes is relatively very ductile the more marked.

contraction of the gills may be suflicient to cause As shown in Fig. 1, the finished tube displays their inner edges to embed themselves in the tube a succession of swellings d, separated from each wall. other by constrictions gripped by the gills.

In order that the gills be imparted a great Fig. 8 illustrates the use of an expansible manstiffness and shall not warp under the internal drel e consisting, for example, of a resilient head pressure exerted by the expanded tube, the gills and of a wedge-shaped member I, adapted to be may advantageously be corrugated or puckered; m'oved intermittently and alternately, so that the' the corrugations formed in the gills thus produce head member e may be expanded whenever situa new effect, in addition to the known one of inated between two gills and thereby expand the 55 It is generallyof advantage that the gills be formed of a highly resilient metal, in order that the edges of their holes surrounding the tube should grip the latter firmly and exert permanent pressure thereupon. On the other hand, the metal of the tube must have a degree of ductility sufhcient to cause swellings to be formed therein ciently stiff to remain unwarped by the expansion stresses set up'by the passage of the mandrel. To this end, the use of corrugated or, puckered fins such as illustrated in Fig. 4 is of special advantage, the gill being stifiened by numerous small folds or puckers formed therein, whereby stresses set up by the expansion of the tube are distributed uniformly throughout said gill without causing the same to warp or distort beyond the recuperative capacity of the metal of which it consists.

The process hereinbefore disclosed may of course be applied to tubes having a non circular cross-section or to an assemblage of fins traversed by several tubes, and the constructional embodiment of the invention may be modified in various ways without departure from its scope as'deflned in the appended claims.

I claim:

1. A process of manufacturing gilled tubes, comprising making gills of a metal substantially more resilient than. the metal of the tubes, threading the gills on a tube, passing through said tube a rigid mandrel of such size with re-' spect to the diameters of the tube and of the holes in the gills, that the tube is permanently deformed while the gills are only elastically deformed, thus causing the gills by their subsequent contraction to form constrictions in the tube and exert a predetermined elastic pressure thereon.

2. A process of. manufacturing gilled tubes, comprising forming gills of sheet metal, hardening the metal of said gills, then threading said hardened gills on a tube of relatively ductile metal, the holes in the gills being just large enough to accommodate said tube, passing through said tube a rigid mandrel of such size with respect to the diameter of the tube that the tube is permanently expanded while the gills are elastically deformed, along the whole periphery of their holes, causing the gills to contract, constrict the tube and exert thereon a predetermined elastic pressure.

3. The process of manufacturing gilled tubes comprising treating the gills to make the metal thereof substantially more resilient than the metal of the tube, then. placing a plurality of tract and form constrictions in said tube.

ROBERT MAUTSCH.

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