Method of making heat transfer pipe

May 14, 1940. j. w. brown, jr 2,201,024

METHOD OF MAKING HEAT TRANSFER FIFE

Filed June 7, 1938

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ATTORNEYS

Patented May 14, 1940

2,201,024

UNITED STATES PATENT OFFICE

2,201,024 METHOD OF MAKING HEAT TRANSFER PIPE

John W. Brown, Jr., Lakewood, Ohio

Application June 7, 1938, Serial No. 212,285

Claims.

This invention relates to improvements in heat transfer pipes and method of making same. The invention has to do with a heat radiating or absorbing unit consisting of a pipe upon which 5 are cast fin sections that completely enclose the pipe and are connected to each other by fluidtight joints formed in the casting operation. In this manner the pipe is protected against the action of moisture, gases or the like. Preferably 10 the fln sections are formed of a non-ferrous metal, not subject to rapid oxidation, such for example as aluminum, while the pipe itself is usually iron or steel and when left partially unprotected, as has been the case heretofore, is sub15 ject to rapid deterioration because of rust.

One of the objects of the invention therefore is the production of protected pipe units having heat radiating or absorbing fins, and the exclusion of moisture from the joints between ad20 jacent sections of the unit,

Other objects and features of novelty will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illus25 trated in the accompanying drawing, in which

Fig. 1 is a central longitudinal section of a fragment of a pipe unit embodying the invention.

Fig. 2 is a cross section taken substantially on a line 2—2 of Fig. 1.

>() Figs. 3 and 4 are sectional detail views, similar to Fig. 1, showing modifications of the invention.

In carrying out the invention', as for instance in making an expansion unit for a refrigerating plant, a length of pipe 10 of suitable dimensions .,5 forms the trunk of the article. Seamless steel tubing is a suitable material for this purpose. This pipe is to be provided with spaced heat transferring flns formed preferably, although not necessarily, of a metal having high heat con49 ductivity, aluminum for example.

The fins, shown at 11 in the drawing, appear as a series of disks intersecting the pipe at right angles. They are in fact annular flanges however, which taper outwardly in cross section, and 45 are cast integral with cylindrical hubs that surround and grip the pipe tightly. Each fln section also has a neck on the side of the flange opposite the hub. In the drawing the hub is marked 12, 12 and 12 in Figs. 1, 3 and 4, re50 spectively, and the neck in the same figures is marked 13, 13' and 13”. These parts are somewhat differently formed in the different modifications, but essentially they are the same, the neck being relatively short and of smaller ex55 teinal diameter than the hub, the latter ex(Cl. 22—203) tending along the pipe to the next fin section and overlapping the neck of that section.

The fin sections, each consisting of a hub, a neck and at least one flange, are cast one at a time in place on the pipe, preferably by the die 5 casting method. In other words, one section is cast on the pipe, the die opened and the pipe with its cast section moved along, when the die is again closed and the next fln section cast, a short time interval being allowed to intervene in order to 10 permit the finished casting to cool somewhat and contract tightly against the pipe and against the neck of the preceding section.

An important feature of the invention is the provision of the neck together with the casting of 15 the hub of the succeeding section around this neck, so that when the hub cools it will contract around the neck of the preceding section and form a joint that is fluid-tight.

It is to be understood, of course, that each sec- 20 tion as cast, instead of including a single flange may comprise two or more flanges.

By following the procedure above outlined the fen ous metal pipe 10 is completely enclosed in a non-ferrous metal jacket, and the succeeding sec- 25 tions of this jacket are so connected together that it is impossible for moisture to enter between them and cause deterioration of the pipe. The method also accomplishes the manufacture of heat transfer pipes of high efficiency at a rela- 30 tively low cost and without machine work of any kind.