US2516689A - Bimetal tubing with ferruled ends - Google Patents

Description

July 25, 1950 w. D. FRANCE ETAL 2,516,689

BIMETAL TUBING wm FERRULED Enns Filed sept. 1:5, 1947 1 ,f u L INVENTORS Water D Faancew By 'Maurice SFr-@sieg Patented July 25, 1950 UNITEDl STATES PATENT, OFFICE nuETAL rvmilrmaaumn ENDS i Application September 13, 1947, Serial No. 773,856 4 Claims. (01.138-64)v This invention relates to bimetal or composite tubes for use in heat exchangers or similar devices and to the method of making the same.

An object of this invention is to improve the structure of bimetal tubes that is manufactured for use in installations wherein diierent media are employed, and the tube is made of two different alloys, so as to make that portion of the 'tube corrosive and erosive resistant to the medium to which it is exposed. Specically the invention resides in the manufacture of bimetal tubes in which the outer tube is made to a predetermined length and considerably short of the ends of the inner tube so as to provide projecting ends of the inner tube over which are assembled ierrules or bushings of the same basic alloy as the inner tube, and wherein all parts are mechanically united together into one solid tube by an expanding operation of the inner tube. Another object is to provide as a complete article of manufacture a bimetal tube unit with which metal ferrules are assembled on the tube ends so that the unit can be furnished ready for insertion in the tube plates without trimming and without the need for the user acquiring and handling the ferrules as separate parts.

Another point of this invention is in the method of manufacture wherein it has been discovered that in expanding the inner tube into the outer tube there is a shortening of the overall length of the inner tube.l This will naturally cause some amount of slippage of the inner tube relative to the outer tube and the ferrule adjacent the final expanded end of the tube. To compensate for this condition in the expanding of the inner tube,

Another object of this invention is to provide .an improved method of manufacture for the Fig. l is a longitudinal sectional view of a bimetal or composite tube embodying the invention as it appears in its finished form.

Fig. 2 is an exploded sectional view showing the parts employed in the composite tube and with Lthe end ferrules in position to be received over the exposed ends of the inner tube.

- Fig. 3 is a longitudinalsectional view showingr all the parts of the composite tube in relative assembled position vand with the tube positioned in portions of the apparatus employed for expanding and eiiecting a mechanical bond between the .various parts of the composite tube.

Fig. 4`is a sectional view of the composite tube as it appears vimmediately after the expanding operation.

Fig. 5 is a sectional view of one end of the tube showing it as secured into a hole or opening in a tube sheet or end plate, and

Fig. 6 is a view similar to Fig. 5 and showing a modified form of assembly of the tube -into an end plate.

Referring now to the drawing i'n which like reference numerals designate like parts throughout outer and inner surfaces of the composite tube 1 are to be exposed. p

For many types of heat exchangers to which our composite tube will be applicable, the outer tube i2 will be one of the ferrous alloys while the inner tube yli and end ferrules I3 and It will be one of the non-ferrous alloys. It should be understood, however, that there' are conditions where this selection of alloys for the respective tubes may be reversed, or where both inner and outer tubes may be of either ferrous or non-ferrous alloys having different corrosion resistant properties, and in general the tubes and ferrulesmay be constructed of any material suitable for resisting the particular corrosive action of the fluids or substances to which they are exposed.

The outer tube i2 will be of a predetermined length for reasons that will appear later and which length is considerably less than the length of the inner tube ii. thus allowing for exposed 3 ends I and I 8 over which the end ferrules Il and I4 are telescoped. Fig. 2 shows in a general manner the amount that the ends of the outer tube I2 are removed from the ends of the inner tube II, thus leaving an exposed end I5 at the left end of the inner tube, and an exposed end I6 at the right end of said inner tube. The O. D. and I. D. of the ferrules I3 and I4 are dimensloned to be the same as the 0. D. and I. D. ai the outer tube I2, and the axial length of these ferrules I3 and I4 preferably are somewhat shorter in length than the exposed ends I5 and IG of the inner tube as will be observed in Fig. 3. Also it will be observed that the. positioning of the outer tube I2 to the inner tube II is such that the right exposed end |`6 is o i greater length than the left exposed end I5, for reasons that will be explained Y later.

While Figs. 2 and 3 of the drawingshow the tubes and ierrules to be in spaced relationship relative to each other, it should be understood that in the preliminary stages, the inner tube I I is dimensioned so as to allow for a free sliding i'lt into the outer tube I2 and end ierrules i3 and I4. In general it has been found that in making composite tubes in the order of one inch size, a clearance of .030" between theo. D. of the inner tube and the I. D. of the outer tube and end ferrules is sufficient to produce a free sliding :Bt between the telescoped parts employed to make the composite tube.

The method and the apparatus by which the various parts are united into one single tubular structure or composite tube is shown in Fig. 3. After the various parts that make up the assembled tube are positioned as shown in Fig. 3, the tubing is conveyed to an expanding machine, the essential parts only of which are employedfor the expanding operation being disclosed in said Fig. 3.

This machine comprises in general a die block Il,- With a through opening I8, having a countersink 18a within` which is tted a hardened support ring I9, against which the adjacent end of the inner tube II is adapted to abut during the expanding operation of the inner tube. A plug member 2li of conventional structure is provided on the end of a long pull rod 2| that passes through the entire length of the inner tube and through the opening I8 in die block I'I. The opposite end of the pull rod 2| may be attached to any suitable draw-bench mechanism, not shown, for the purpose of pulling the plug 2II through the inner tube II for expanding the same. The plug 2U is preferably of a double diameter wherein the leading end 22 is of a size to t snugly into the open end of the inner tube I I, while the trailing end 23 is of a size for expanding the inner tube the proper amount into the outer tube I2 and end ferrules i3 and I4 to create a iirm m'echanical bond therebetween, and also giving due the operation of pulling the plug through thev inner tube I for purposes oi.' expanding the same, without necessarily reducing its wall thickness, a shortening of the overall length of said inner tube I I will result. With this physical change of the length of said inner tube Il, but with no change in length of the outer tube I2 and end 1errules I3 and I4 will naturally cause a proportionate amount of axial slippage as between the inner tube II and outer tube I2 and right ferrule I4. This added length at the right exposed end Il is to allow for this reduction in the overall length of the inner tube II, and still leave a portion of the inner tube exposed and projecting beyond the end of the right ferrule I4 upon completion of the expanding-operation, in a manner as shown in Fig. 4.

In compensating for this slippage as between the inner and outer tubes and I2 and right ferrule I4, the exposed end of the right ferrule Il is abutted' against a resilient member, which may be in the form of a iloating ring plate 24 slidably mounted in a bracket 25 attached to the adjacent face of the die block Il, illustrated in Fig. 3. A plurality of sockets 26 may be provided in the adjacent face of the die block I1 and annularly arranged about the-support ring I9. A plurality of coil springs 21 is provided and being individually fitted into eaeh of the sockets 2B with the outer ends of said springs abutted against the inner face of the floating ring plate 24. From this apparatus construction it will be noted that in the method of manufacture of the composite tube ill, the inner tube il is :Erst abutted against a support ring i9, immovably held in the die block Il and then the outer tube I2 and end ferrules I3 and i4 as a imit are abutted against the iioating ring plate 25 that is capable of resiliently giving due to the springs 21. As the expanding plug 20 isV being drawn through the inner tube I in the same into a hrm mechanical bond with the outer tube I2 and end ferrules I3 and I4, the inner tube l! as a result will contract in length and, in e'eet, be drawn inwardly from the right ferrule il and then cause the outer tube i 2 and right ferrule i4 to move to the right carrying the iioatng ring plate 24 therewith against the inuence of the springs 21. When the expanding operation fn completed the resulting composite tube iii will be iinished substantially-as shown in Fig. -igwlth portions of the inner tube II exposed beyond the ends of the assembled ferrules I3 and Il, said ends being designated as |5a and isa. These ends Ia and IGa may subsequently be cut away to the dot-and-dash line 28 (see Fig. 4) so as to bring the ends of the inner tube li iiush with the exposed ends of the ferrules I3 and l5.

Fig. 5 shows one form of installation to which our bimetal ferruled end tubes may be assembled, it being considered suiiicient to show only one end of the tube connection as both ends will be of like construction. The tube Il is assembled to an end plate or tube sheet 29, having an opening 30 of a size to receive the O. D. of the outer tube I2. Within this plate opening 39 are provided a series of annular recesses 3|.

The tube is permanently assembled to the tube sheet or end plate 29 by a suitable tool (not shown) that serves to expand the adjacent open end of the inner tube II as at 32, the expanding force being usually of a character to increase the diameters of the inner tube and the surrounding ferrule and adjacent end of outer tube I2. The expansive force in the inner tube Il should be of a character to cause the material of the outer ferrule to be forced into the annular re- Acesses 3|. In case the outer tube I2 happens to be made from a comparatively hard alloy, such chanicall bond and leak-proof the tubes I and end plates 29.

as steel, it is perceived that only a portion of i this tubing will be expanded into the adjacent unit.

assembling end ferrules at the place where the tube to be assembled into a heat exchanger Also by reason of the fact that it is only neces# sary to remove the short end portions Ia and IBa or the inner tube by a cutting operation to produce the finished tube as shown in Fig. 1, there 1s eliminated the problem of mixed scrap which has heretofore been one of the problems of fabrias shown in Fig. 5. In a composite tube wherein the outer tube I2 is of a harder ferrous material,

experience has taught that the material of this tube will be only partially expanded into the adjacent annular recess 3I surrounding said tube. whereas the end ferrules I3 and I4 beingusually of a non-ferrous and softer material, the material thereof will expand ,into substantially the full depth of the one or more recesses 3| surrounding the same to assure an adequate me- Joint as between In Fig. 6 is shown a modified form of `joint wherein the composite tube Ilia may be secured into an end plate 29@ having a flared opening 26a. In fabricating al composite tube for this. particular installation, the length of the inner tube Ila will be initially predetermined so that when Ithe 'mechanical bond is eiected with the outer. tube and end fer-rules, the exposed ends I5a and I 6a willbe somewhat longer than what would be required for the Fig. 5 installation (it being understood that for the latter installation the inner tube is -cut olf ush with the end ferrules before the installation). The reason that these exposed lengths or ends I-5a and I6a are left longer is because of the difficulty of control in thel expanding operation. By leaving a longer length to the exposed ends I5a and I9a of the inner tube, these lengths can then be cut oil to a predetermined length from the ends of the end ferrules to t the required need ofthe Fig 6 installatlon. In assembling the composite tube Illa in the ilared opening 29a, the inner tube IIa and also the adjacent bushing IIa will be ilrst expanded by a suitable tool in the manner as described in connection with Fig. 5, and then by another suitable tool flared outwardly in the.

manner as shown in Fig.l 6. By reason of the predetermined cut length or exposed end I5a of the inner tube IIa that is exposed beyond the end of the outside tube lila and adjacentferrule I3a, even after the end of the composite tube is expanded by the rst aring operation,

` the exposed end I5a of the inner tube Ila will be of sufilcient length to allow said length Ila to be `further ared over as atv 33 and conceal the exposed end of the flared bushing I 3a, and serve to make a neat jointwith the end plate 29a.

One of the advantages of this invention is' that the entire composite tube I0 can be made and shipped as a unit from the place of manufacture without resorting to'any cutting or milling operations of the tube for the purpose of eating bimetal tubes for the various installations. v

While we have herein described and upon the `drawing shown an illustrative embodiment of the invention and apparatus for producing the same, it is to be understood that the invention is not limited thereto, but may comprehend other constructions and arrangements without departing from the spirit of the invention and details of parts.

What is claimed:

-1. As an article-of manufacture, a bimetal tube comprising an inner tube `of one alloy and an outer tube of a different alloy extending over the greater, part of the length of the innerv tube, the

ends of said inner tube projecting beyond the ends of lthe outer tube, ferrules of an alloy comparable 'tov the inner "tube surrounding the exposed ends of aid inner tube and extending over at least the greater part of the length of said exposed ends, and said tubes and ferrules being mechanically bondedv together as oneintegral tube unit ready for assembly with a heat exchanger or the like.

. 2. .As an articlev of manufacture, a bimetal tube comprising an inner tube of relative soft metal and an outer tube of relatively hard metal extending over the greater part of the length of the inner tube. the ends of said inner tube projecting beyond the outer tube, and ferrules of a metal comparable in hardness to the inner tube. surrounding the exposed ends of said inner tube and extending over atleast the greater part of the length of said exposed ends, said tubes and ferrules being mechanically bonded together as one unit ready for assembly with tube sheets of a heat exchanger or the'lik 3. The bimetal tube dened in claim 1 wherein the inner tube extendsslightly beyond the v ferrules at each end of the finished tube.

4. The bimetal tube defined in claim 1 wherein the.length of the ferrules is the same as the length of the exposed ends of the inner tube.

WALTER D. FRANCE. MAURICE C. PRESLEY.

REFERENCES CITED The following references are of jrecord in the file of this patent:

UNITED STATES PATENTS r2,386,147 als oct. 1e, 1945

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