US3280851A - Fabricated finned tubing - Google Patents

Description

Oct. 25, 1966 E. P. HABDAS 3,280,851

FABRI CATED FINNED TUBING Filed May 10, 1965 FIGS INVENTOR.

EDW RD P. HABDAS ATTORNE S United States Patent Oflice 3,280,851 Patented Oct. 25, 1966 3,280,851 FABRICATED FINNED TUBING Edward P. Habdas, Dearborn, Mich, assignor to Calumet & Hecla, Inc., Allen Park, Mich., a corporation of Michigan Filed May 10, 1965, Ser. No. 454,587 Claims. (Cl. 138-154) This is a continuation-in-part of applications Serial Nos. 201,511 and 201,515, both filed June 11,1962, now US. Patents Nos. 3,240,177 and 3,240,042. respectively.

The present invention relates to fabricated tubing.

It is an object of the present invention to provide tubing in the form of a continuously wound strip of U-shaped cross-section in which the side flanges of the U have been tapered to diminishing thickness progressively in such a way that the tapered edge flanges cause the strip to wind into a coil.

It is a further object of the present invention to provide a tube from U-shaped strip having a web and edge flanges in which the edge flanges are tapered to diminishing thickness outwardly of the web, and in which the outer surfaces of the flanges are bonded together to form a unitary tubing having an integral flange formed thereon.

It is a further object of the present invention to provide a finned tube in which the fins are produced by bonding together outer edges of laterally extending and tapered flanges to produce a unitary flange which is also tapered to diminishing thickness outwardly of the tube wall.

It is a further object of the present invention to provide finned tubing produced from U-shaped strip having a web and relatively Wide flanges extending outwardly from the web, the flanges being of suflicient height to produce eflicient heat transfer fins, the outer surfaces of adjacent convolutions of the strip being bonded together.

It is a further object of the present invention to provide tubing formed of U-shaped strip having a central web and laterally turned flanges, the flanges being tapered to diminishing thickness outwardly of the web and bonded together, one of the flanges being relatively wide and operative to perform efliciently as a heat transfer fin, the other flange being relatively narrow and bonded throughout its lateral surface area to the portion of the relatively wide flange adjacent the web of the U-strip.

It is a further object of the present invention to provide flexible tubing formed of generally U-shaped strip having a central Web and laterally extending flanges tapered to be of diminishing thickness outwardly of the web, the strip being coiled into a tight helical configuration in which the outer surfaces of the flanges of adjacent convolutions are bonded together in a helical zone extending inwardly from the outer edges of the flanges for a distance substantially less than the full width of the flanges.

It is a further object of the present invention to provide tubing as described in the preceding paragraph in which the portions of the flange intermediate the helically extending bonded zone and the webs diverge.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating preferred embodiments of the invention, Wherein:

FIGURE 1 is a diagrammatic view illustrating a preferred method of producing the tubing disclosed herein.

FIGURE 2 is a sect-ion on the line 22, FIGURE 1.

FIGURE 3 is a section on the line 33, FIGURE 1.

FIGURE 4 is an enlarged section of a portion of FIG. URE 1.

FIGURE 5 is an an enlarged sectional view of a portion of FIGURE 1.

FIGURE 6 is a fragmentary section through a U- shaped strip of different proportion.

FIGURE 7 is a view of the strip shown in FIGURE 6 after its flanges have been tapered.

FIGURE 8 is a fragmentary sectional view of tubing produced from U-shaped strip of the configuration illustrated in FIGURE 7.

FIGURE 9 is a longitudinal sectional view similar to FIGURE 8, showing another embodiment of the invention.

FIGURE 10 is a longitudinal sectional view similar to FIGURE 8, showing yet another embodiment of the present invention.

The present invention includes tubing, preferably metal tubing, of any convenient size, but is particularly useful in the production of relatively large light-walled tubing such for example as is used in irrigation fields. Tubing of this type is generally transported manually from place to place and since it is not subjected to any relatively great internal pressure, it may be relatively thin-walled.

However, it is necessary for tubing of this type to be sufiiciently stiff so as to permit its transportation without alteration of its generally cylindrical configuration.

As seen in FIGURE 1, such tubing is indicated generally at 10 Where it is shown as located on a rotating mandrel 12. The portion of the tubing seen at 10a includes a helical flange, fin or bead 14, the nature and method of production of which will subsequently be described. For the present however, it is to be noted that this continuous helical flange constitutes a stiffening means which renders a substantial length of the tubing selfsupporting, at least sufficiently so as to permit ready transportation. The fin 14 as previously described, may be relatively low or in fact may be flattened down against the tube, as will subsequently be described. Alternatively, it may be relatively high so as to constitute an efficient heat transfer means.

If desired, and as a modification of the tubing as illustrated, the flange, fin 0r bead 14 may be bent over and flattened against the outer cylindrical surface of the tub ing as indicated at 1412, as best illustrated in FIGURE 5. It will of course be apparent that for maximum stiffness the flange 14 should be left to extend generally radially as designated in the zone 10a. Where such stiffness is not required the flange may be bent down as indicated at 1411.

The nature of the tubing is best understood from a description of the method of producing it. As best seen in FIGURE 1, a continuous flat strip 20 is advanced for example from a storage reel, through a forming station designated 21 in which inner forming rolls 22 and 24 are carried by a support 26 and cooperate with outer forming rolls 27 and 28 respectively. The advance of the fiat stock through the forming station 21 results in forming this trip into U-shaped cross-section comprising a central web having edge portions bent upwardly into the indi vidual flanges 30 and 32, as best seen in FIGURE 2. Since the operation carried out at the forming station 21 is essentially a bending operation, it will of course be apparent that the bent up flanges 30 and 32 are of uniform thickness from edge to edge, and that accordingly, the strip 20 as it advances beyond the forming station 21, remains essentially a flat strip.

At a forming station 34, which is directly adjacent the rotating mandrel 12, means are provided for edge thinning or tapering the edge flanges 30 and 32 to the crosssection illustrated at 30a and 32a in FIGURE 3. This tapering operation is accomplished by edge thinning rolls 35 and 36 operating against a stationary anvil 38. It will of course be understood that instead of a solid anvil 38, a block similar to the support 26 provided with inner rolls opposed to the outer rolls 35 ad 36 may be provided.

It is to be noted at this time that the rolling operation performed by the rolls 35 and 36, together with the anvil 38 or inner rolls if preferred, is an operation in which the edge flanges are tapered by rolling them longitudinally in the longitudinal direction of the strip. Elongation of material rolled in one direction takes place substantially completely in the direction of roll and the amount of elongation bears a direct relationship to the amount of reduction in thickness resulting from the rolling operation. Accordingly, the relatively thin outer edges of the flanges become longitudinally elongated as compared to the web of the strip, and this causes the strip as a Whole to tend to coil as seen in FIGURE 1. This coiling of the strip is guided so that the strip coils helically about the mandrel into a tight helical configuration with the outer surfaces of the tapered flanges, or portions thereof,.abutting. Portions of the outer surfaces of the flanges are permanently bonded together as by Welding.

In order to carry out this operation most efficiently, the anvil 38 and the thinning rolls 35 and 36 are located as closely as possible to the zone of tangency between the advancing generally flat strip 20 with the cylindrical surface of the mandrel 12. Thus, referring to FIGURE 1 it will be observed that the rolls 35 and 36 are in alignment with the axis of the mandrel and hence, are not located directly opposite each other across the width of the advancing strip 20. This arrangement tends to form the strip into a helical path and its exact position is determined by engagement with the rotating mandrel.

In FIGURES 1 the roll 36 operates with the anvil 38 to form the right hand flange 32 into the required tapered form illustrated at 32a by direct engagement with opposite sides thereof. The roll 35 however, cooperates with the anvil to receive therebetween not only the flange 30 of the advancing strip, but also the tapered flange 32a, as it advances around to start the second convolution.

Instead of having the roll 35 operate to taper the flange 30 against the anvil 38 through the previously tapered flange 32a as suggested in full lines in FIGURE 1, it may operate in advance of the full line position, as for example in the dotted line position designated 35a, in which case it will impart a taper to the flange 30 to the shape illustrated at 30a, FIGURE 3, prior to engagement of the flange 30a with the flange 32a of the preceding convolution. Roll 36 is then preferably operated in the position illustrated in dotted lines at 36a.

In addition to edge thinning or tapering the flanges 3t) and 32 to the configuration illustrated at 30a and 32a, the anvil 38 and the roll 36 serve as abutment means insuring continuous advance of the helically coiled strip on the rotating mandrel. Since the direction of advance of the strip as it engages the surface of the mandrel is different from the instantaneous direction of movement of the engaged surface of the mandrel, it will of course be apparent that the tube assembly is in effect sliding continuously longitudinally. I

Means are provided for bonding the confronting surfaces of the tapered flanges 30a and 32:: so as to form the helically wound strip into a continuous sealed tube. This means is illustrated in FIGURE 1 as taking the form of a pair of welding electrodes 40 and 42 shaped to press the flanges 30a and 32a into firm contact and to effect a weld by elevating the temperature of the flanges by current passing therethrough. Obviously, the welding action may be controlled by the pressure exerted on the flanges by the electrodes 40 and 42, the angular extent of the electrodes, the Welding current applied to the electrodes, and the rate of advance of the strip 20. It will further be understood that the welding operation as illustrated and described herein is merely one convenient plied by rotating the mandrel and drawing the strip through the rolls 22, 24, 27, 28, and 36. However, since the material may in most cases be relatively thinwalled, it is ordinarily desirable to effect powered rotation of certain of the rollers, particularly the rollers 35 and 36. In some cases the mandrel 12 may be rotated so as to maintain tension in the strip.

While the present invention is particularly applicable to the production of metal tubing for example as aluminum or aluminum alloy tubing, it is apparent that the tubing may be of other metals or of plastic, in which case elements and 42 may simply be heated elements for effecting thermal bonding of the fins.

Referring now to FIGURES 6-8 there is illustrated another embodiment of the invention. In this case a strip is bent to U-shaped configuration so as to comprise .a web 54 and flanges 56 and 58. The flanges 56 and 58 may be rolled longitudinally by mechanism equivalent to that illustrated in FIGURE 1 so as to produce tapered flanges 56a and 58a. This U-shaped cross-sectional tube is coiled around the mandrel in the same manner as dis closed in FIGURE 1, to produce the tubing illustrated at 60 in FIGURE 8 where the tapered flanges 56a and 58a are bonded together throughout their height to produce correspondingly tapered relatively high heat transfer fins 62. -It will be observed that the fins 62 taper substantially uniformly from the base or root to the outer edge thereof. This arrangement provides for maximum utilization of material since the cross-sectional thickness of the fin reduces as the necessity for heat conduction is reduced by the loss of heat from the surface of the fin. More over, the tubing illustrated in FIGURE 8 provides for maximum strength of bond since the bond between the outer surfaces of the edge flanges may occupy a relatively method of effecting a satisfactory bonding of the strip.

If it is desired to eliminate the generally radially outwardly and helically extending fin 14, it may be rolled down to the configuration illustrated at 14b in FIGURE 5 by a flattening roller 50 located adjacent the mandrel 12 in position to engage the flange as it advances.

Advance of the strip onto the mandrel may be accomgreat area. Finally, the construction illustrated in FIG- URE 8 is of great utility in that the tapered flanges in addition to serving as eflicient heat transfer fins, constitute structural portions of the tubing giving the tubing mechaical strength without requiring a wall thickness in excess of that required to withstand anticipated pressure difi'erenges between fluid within the .tube and outside of the tu e.

Referring now to FIGURE 9 there is illustrated yet another embodiment of the invention in which the tube 64 is formed from strip having a web 66, a relatively high tapered edge flange 68, and a relatively narrow edge flange 70. The outer surface of .the flange 70 is welded or otherwise bonded to that portion of the outer surface of the flange 68 adjacent to the web- 66. With this arrangement most eflicient utilization of material is employed since the relatively high flange 68 forming the fin may be designed for most eflicient heat transfer, Whereas the bond between adjacent convolutions requires only the relatively low or narrow flange 70 for satisfactory integrity of the tubing.

'In FIGURE 10 there is illustrated yet another embodiment of the invention which is characterized particularly in flexibility of the completed product. In this case the tubing 72 is formed of a generally U-shaped strip which when coiled has an inner relatively narrow web 74, outwardly diverging flange port-ions 76 terminating in outer edge portions 78 adapted to abut in surface to surface engagement as illustrated. The outer edge portions of the flanges or fins are suitably bonded together and the inwardly diverging flange portions provide substantial lateral and some longitudinal flexibility or stretchability of the compieted tube.

The drawings and the foregoing specification eonstitute a description of the improved fabricated finned tubing and apparatus for making the same in such full, clear, concise and exact terms as to enable any person skilled in the ant to practice the invention, the scope of which is indicated by the appended claims.

What I claim as my invent-ion is:

1. Thin-walled tubing formed from flexible fiat strip and consisting in its entirety of a single continuous helica-lly wound strip having both edge portions turned to form the strip to substantially U-shaped cross-section having edge flanges extending in the same direction from said strip substantially perpendicular therefrom and radially of the tubing, said flanges being of substantially uniformly tapered thickness from the inner to the outer edge thereof, the outer surfaces of said flanges being substantially fiat surfaces in substantially surfaceto-surface contact and bonded together throughout the area of contact.

2. Tubing as defined in claim 1 in which at least one of said flanges is of a width sufiicient to form an eflFective heat transfer fi-n.

3. Tubing as defined in claim 1 in which both of said flanges are of a Width suflicient to form an efiective heat transfer fin.

4. Tubing as defined in claim 1 in which said flanges are of substantial equal width and taper at their free edges to substantially knife-edges.

5. Tubing as defined in claim 4 in which said flanges are bonded together substantially throughout their entire width several times greater than the thickness of the wall outer surfaces to produce a continuous sealed joint of a thickness of the strip from which the tubing is produced.

References Cited by the Examiner UNITED STATES PATENTS LAV ERNE D. GEIGER, Primary Examiner.

C. HOUCK, Assistant Examiner.

Claims (1)

1. THIN-WALLED TUBING FORMED FROM FLEXIBLE FLAT STRIP AND CONSISTING IN ITS ENTIRETY OF A SINGLE CONTINUOUS HELICALLY WOUND STRIP HAVING BOTH EDGE PORTIONS TURNED TO FORM THE STRIP TO SUBSTANTIALLY U-SHAPED CROSS-SECTION HAVING EDGE FLANGES EXTENDING IN THE SAME DIRECTION FROM SAID STRIP SUBSTANTIALLY PERPENDICULAR THEREFROM AND RADIALLY OF THE TUBING, SAID FLANGES BEING OF SUBSTANTIALLY UNIFORMLY TAPERED THICKNESS FROM THE INNER TO THE OTHER EDGE THEREOF, THE OUTER SURFACES OF SAID FLANGES BEING SUBSTANTIALLY FLAT SURFACES IN SUBSTANTIALLY SURFACE-TO-SURFACE CONTACT AND BONDED TOGETHER THROUGHOUT THE AREA OF CONTACT.

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