US2173665A - Finned tube construction - Google Patents

Description

Sept. 19, 1939. s E I 2,173,665

FINNED TUBE CONSTRUCTION Original Filed April 20, 1936 3 s s 1 as fififi yum 1 I 2. 53 .36" 34 .34 i .74

E11 E- I INVENTOR.

F/oyc/ J. SI'b/ey BY 9M 3.3%

A TTORNEY.

F. J. SIBLEY FINNED TUBE CONSTRUCTION Sept. 19, 1939.

Original Filed April 20, 1936 3 Sheets$heet 2 INVENTOR. F/oyo/ J- SI'b/ey A TTORNEY.

Sept. 19, 1939. F. .1. SIBLEY I 2,173,665

' FINNED TUBE CONSTRUCTION Original Filed A ril 20, 1956 s Sheets-Sheet s INVENTOR. Floyd J: Sibley BY Q-MAWJ 3.9%

A TTORNEY.

Patented Sept. 19, V 1939 UNITED STATES FINNED TUBE CONSTRUCTION Floyd J. Sibley, Detroit, Mich.

Original application April 20, 1936, Serial No. 75,326. Divided and this application March 2,

1937, Serial No. 128,647

3 Claims My invention pertains to an improved finned tube construction and more particularly to a method of securing a plurality of plates spaced upon a tube for heat exchanging and other purposes, and this patent application is a division of my patent application Serial No. 75,326; filed April 20, 1936, for Finned tube construction.

It is an object of my invention to provide an improved method of assembling and securing w fin plates in spacedrelation upon a tube for heat exchanging and other purposes which provides greater conveniencein assembling, greater mechanical strength, and increased thermal efilciency while eliminating thenecessity of utilizing auxiliary securing means or -material.

It is also an object of my invention to provide an improved method of securing fin plates on a grooved tube comprising diametrically expanding while axially shrinking the tube to firmly abut the bottom of the groove against the inturned edges of the plates and to grip and squeeze the opposite sides of the plates between the side walls of the groove whereby a three-sided thermal conductive joint is provided.

It is a further object of my invention to provide an improved method of assembling and securing apertured fin plates upon a grooved tube which comprises passing the tube through the apertures to dispose the intumed edges into the grooves,

and expanding the tube by means of a sharp edged expander for abutting the bottom oI the groove against the inturned edges of the aper-- tures while clamping the sides of the plates to provide a three-sided joint for supporting the plates.

Another object of my invention is to provide an improved method of assembling fin plates upon tubes which comprises providing in said plates spaced helically edged apertures of alternately right-handed and left-handed conformation, providing in the peripheral surfaces of said tubes helical grooves of alternatelyright-handed and left-handed conformation, rotating said tubes simultaneously in alternative reverse directions, and guiding the hellcally edged apertures of the plates simultaneously into and along said grooves.

The invention itself, however, both as to its construction and as to the method of and apparatus for assembling the same, together with additional objections and advantages thereof, will best be understood from the following description of lficembodiments,,,when read in con- 55 junctidn with mt accompanying drawings, where like reference characters are applied to similar parts throughout and in which:

Fig. l is a side elevational viewot a fin plate pierced and cut to provide helical edged apertures for receivingfour tubular conduits there- 5 through;

Figs. 2 and 3 are sectional views on lines 2-2 and 3--3 thereof;

Fig. 4 is a side elevatlonal view of a tube having a helical groove for receiving and securing a set m of fin plates thereon;

Fig. 5 is asimilar view showing a tube provided with a plurality of spaced helical grooves for securing a plurality of separated sets of mutually engaging fin plates; 15

Fig. 6 is a longitudinal sectional view showing a grooved tube provided with a leader clamped in the end preparatory to assembling the fin plates thereon; I

Fig. 7 is elevation view showing how the fin 20 plates are guided onto the grooved tube;

Fig. 8 is a side elevational view showing a device for rotating a plurality of grooved tubes simultaneously for receiving the fin plates thereon;

Fig. 9 is a longitudinal sectional view showing 25 how the grooved tube is expanded for firmly gripping the assembled fin plates;

Fig. 10 is an elevation view showing the assembly of a set of continuously contacting fin plates clamped upon an expanded tube, a por- 30 tion of which is broken away to show the contacting plate tabs;

Fig. 11 is a similar view showing a tube provided with a plurality of helical grooves supporting a plurality of continuously contacting sets of 5 fin plates in spaced relation;

Fig. 12 is a side elevation view of a difierent, embodiment of a fin plate comprising a helical edged aperture;

Figs. 13 and 14 are sectional views on lines o l3-|3 and -44 thereof;

Fig. 15 is a side elevatlonal view showing such fln plates assembled on a grooved tube before expanding the same;

Fig. 16 is a rear view thereof enlarged;

Fig. 17 is a sectioned elevational view of an embodiment of the invention comprising a tube having annular grooves deformed by expansion and shrinkage to firmly grip and secure plates disposed thereon for constructing multiple disc v cutters, electrical condensers and the like.

Fig. 18 is a side elevational view of another embodiment of fin plate; and

Fig. 19 is an end elevational View thereof. Referring more particularly tov Figs. 1, 2 and 3- which is provided with four circular apertures 3 for mounting on tubular members when the structure is assembled. The fin plate'I is cut through by slits 5 extending between each of the pairs of apertures 3 adjacent the opposite ends of the fin plate to provide flexible tabs or wings I and 9 between the adjacent pairs of apertures. The adjacent pairs of tabs 1 and 9 are bent outwardly from the surface plane of the plate I in opposite directions, one of the tabs I of each pair projecting to the right and the other tab 8 of each pair projecting to the left, as viewed in Fig. '2, thereby distorting the edges of the apertures 3 into a substantially helical or spiral curvature.

The opposite sides of the plate I are also distorted or off-set into displaced substantially parallel planes 6 and 8 to further distort the edges of the apertures 3 and the intermediate portion of the plate to provide a helically edged .aperture which will be a full circle in projection and which will fit freely into and contact fully around a helical groove on a tube. This ofl'-set ar rangement is more clearly shown in Fig. 2, but is also indicated by the shaded portions in Fig. 1. The screw-threaded apertures thus formed are alternateiy right and left handed and any desired number may be conveniently provided in each plate.

The distorted edges of the apertures 3 are also preferably provided with an annular margin II), as shown in Fig. 3, which is substantially parallel to the displaced edges of the plate I. Since the annular margin I0 encircling the apertures will be substantially at right angles to the axis of the tube, on which it will be mounted, it will enter the groove in'the tube very readily. Because of the helical or spiral shape of the'edges of the apertures thus provided in the fin plates, the plates may be secured upon a helical grooved tube and the maximum contact area with the tube is obtained.

The fin plates I may be pre-formed by hand tools and may be made of various shapes and with apertures to accommodate various members and arrangements of the tubes as desired. For mass production the plates may be pre-formed by automatic sheet metal working machinery, in any suitable manner, as by a punch press provided with a suitable die, as will be readily understood.

In the first station the holes are preferably pierced, slightly smaller than the finished hole, and in the second station the cuts may be made between the holes and the plate tabs may be distorted and the holes shaved to the final size. Suitable automatic sheet metal working machinery is well known in the art and does not constitute any part of the applicant's invention.

Because it is only necessary to bend the fin plates I but slightly in accordance with my invention, it is possible to make them of a very hard sheet metal of high density and thermal conductivity as itcomes from'the rolling mills. These plates may be assembled with high pressure engagement to provide good thermal contact.

After the pre-formed fin plates I have been provided with apertures 3, the edges of which are of substantially helical conformation, they may be conveniently and efficiently assembled upon a tube II which, as shown in Fig. 4, has a groove l3 formed, cut, or sawed in any convenient manner around its outer peripheral surface. The groove I3 is preferably of substantially helical conformation either right or left handed. Such a tube may be made of any material which has a suitable modulus of elasticity to take sufficient permanent distortion to be expanded diametrically and shrunk axially in accordance with my invention, for drawing the side walls of the grooves together to grip and hold the fin plates, in a manner to be subsequently set forth. The grooved tube II may be made of any suitable length for supporting the desired number of plates for various applications and installations. For heat exchanging'purposes the grooved tube I is made of a metal of good heat conductivity having high ductility. For example, half hard copper, aluminum, or soft steel are suitable for thisv purpose.

A portion of the outer surface of the tube adjacent each end thereof may be turned down to provide a smooth surface of smaller diameter whereon the ends of the tube may be conveniently connected, in any suitable manner, with the source of heating or cooling or other medium which is to be utilized therein. When it is desired to support a plurality of separate sets of mutually engaging fin plates in spaced relation, the grooved tube II must be provided witha plurality of helical grooves, such as, I3 and I5 spaced thereon, as shown in Fig. 5 for example. It will be understood that more than two grooves maybe thus provided in spaced relation on the tube.

For the purpose of assembling the apertured fin plates I upon a grooved tube II, I provide a leader II which, as shown in Fig. 6, is secured in the end of the tube. For this purpose the leader comprises a guide neck I9 having a shallow helical thread 2| on its outer surface for guiding the fin plates toward a leader head 23. The guide neck I9. and its external thread 2| are of a diameter smaller than the diameter of the apertures 3 pro vided in the fin plates whereby the plates may be readily dropped onto it.. The leader head 23 is of substantially larger diameter than the neck and it is provided with a deep helical groove 25 for receiving the fin plates from the guide neck IS. The inner diameter of the helical groove 25 on the leader head is substantially larger than the neck I 9 ,and is suitable for continuously guiding the fin a tube II, a shaft 21 extends freely through theleader and carries a tapered wedge 29 thereon for spreading a set of split fingers 3| which extend from and are integral with the head 23. For this purpose, two fingers 3| of semi-circular crosssection are sufficient and these are provided at the inner ends with a substantially tapered cam surface 33 for receiving the wedge-like head 29 on the end of the shaft. The shaft 21 is provided with external threads 35 which cooperate with internal threads between the friction fingers 3I adjacent the leader head for drawing .the wedge 29 toward the leader head 23. This spreads the friction fingers 3| apart in snug frictional engagement with the inner surface of the tube II, as shown in Fig. 6. v

The outer end of the leader shaft is provided with a square shank 22 for receiving a suitable wrench or hand-wheel thereon. It will be under stood that anynumber of friction fingers 3| may be utilized to provide snug engagement with the 2,178,065 roughened to provide suitable gripping engagement with the tubes.

When the leader is applied to the end of a tube, it is firmly secured therein by turning the shaft 21 to expand the fingers'il for engaging the tube. The leader is so applied that the end of the large groove 25 in the leader head suitably connects with the end of the fine helical groove I3 in the tube wherein the fin plates are guided onto the tube. Leaders are provided with right or left handed threads to fit the right and left handed grooved tubes.

After the leaders have been properly installed on the ends of a suitable number of the tubes I I, which are arranged alternately with right and left handed grooves, the fin plates I are dropped on over the guide necks I9. By turning the tubes II simultaneously in alternate reverse directions, the leaders are rotated relative. to the fin plates I which are thereby guided forward and enter the deep helical grooves 25 in the leader heads in adjacent relation. By continuing the rotation, the fin plates I are started into the helical grooves I3 of the tubes. The fin plates I, shown in Fig. 1, are thus simultaneously guided upon four grooved tubes II which extend through the four apertures 3 of the plates. The leaders H are then removed from the tubes by turning the shafts 21 in the reverse direction.

For convenience in rotating the tubes Il simuitaneously, I provide the assembling device shown in Fig. 8, which comprises chucks 24 of asuitable size for receiving and gripping the lower ends of the grooved tubes II. The chucks24 are rotatably supported on the upper ends of individual shafts 26 which are vertically joumalled in a base plate 28. The base plate 28 also supports a bearing bracket 30 which has depending end legs 32 secured to the ends of the base plate. 28 in any suitable manner. The shafts 26 rise vertically through the bracket 30 which comprises bearing means therefor.

The shafts 26 carry gears 34, which mesh together for rotating the shafts simultaneously in alternate reverse directions. For driving the shafts 26, a drive shaft 36 is similarly journalled in the base 28 and the bracket 30 and it carries asuitable gear 38 intermeshing with the adjacent one of the series gears 34. The drive shaft 35 may be turned manually, or by any suitable motive means such as the electric motor 40 connected thereto through gears 42 or other suitable speed changing means.

The order in which these steps are performed is immaterial as the tubes I I may be first mounted vertically in the assembling device chucks 24 and the guides I'I thereafter installed in the upper ends of the tubes and the apertured fin plates dropped thereon.

After the set of helically apertured fin plates is assembled on the tubes, the guides are removed from the upper ends of the tubes H by turning their shafts 21 in the reverse direction. On the lower ends of the tubes, the chucks 24 are released and the fin tube assembly is removed. In this manner any desired number of plates may be simultaneously assembled upon any number of grooved tubes.

For gripping and securing the fin plates I I upon the grooved tubes, I collapse the grooves to pinch the plates therein after the plates have been assembled on the tubes. For this purpose, I provide an expander which, as shown in Fig; 9, comprises an elongated stem 4| for extension through the tube II which is to be expanded. An enlarged expander head 43 is provided on the end of the stem and it carries a substantially sharp shoulder 45 extending in annular conformation around the leading edge of the peripheral surface of the head. For best results-the leading shoulder 45 is so sharp and snug that it shaves off any metal which projects into the tube instead of expanding it. A series of friction reducing guide rings 41, comprising ridges extending circumferentially around the outer surface, are spaced axially along the expander head. Also the portion of the stem 4| joining the expander head is provided with a plurality of axially spaced annular guide rings 49.

' To expand the tube II, the expander stem 4| passes freely therethrough, as shown in Fig. 9. The expander head 43 is then drawn through the grooved tube for which purpose force may be ap-' plied in any suitable manner as by mechanical, pneumatic or hydraulic means as will be readily understood. As the expander passes through the tube, the annular guide rings 41 and 49 on the stem and the expander head serve to reduce the frictional losses which would be obtained if fiat contacting surfaces were provided. The shoul-' der 45, which is rather sharp, on the leading edge of the expander head 43 packs or collapses the tube II in the weakest portions under the grooves I3 thereby shrinking the grooves axially. The

leading shoulder 45, being sharp and snug, shaves :off any metal projecting into the tube. The diametrical expansion of the tube instead of expanding the projecting metal also requires additional metal for increasing the diameter some of which is taken from the length of the tube which is thus shrunk or shortened axially. As this takes place the side wallsof the grooves move together. This efiect also augments the 'groove collapsing effect caused by expandingthe tube with my expander.

Thus as the expander is drawn through the tube, the tube is expanded diametrically and shrunk axially and the side walls of the helical grooves are drawn together to pinch or squeeze the edges of the helical apertures of the fin plates mounted thereon, while the bottoms of the helical grooves are expanded diametrically into snug abutting engagements.

After the tubes II have been expanded, the

assembly of a set of continuously contacting fin plates I is clamped together thereon, as shown more clearly in Fig. 10, where a portion of the tube I I is broken away to show the mutually engaging relation provided between the plates. The oppositely disposed plate tabs I and 9 abut the tabs 9 and I respectively projecting from the plates on opposite sides and provide a continuous air fiow engaging surface between the parallel offset portions 6 and 8 of the'plates with sufiicient irregularity to provide eddies for efficient heat transfer. The helical edged apertures provide continuous thermal coupling between the plates and the tube and provide a rigid support around the helical groove from one end of the tube to the other. The fin plates I are supported ll].

axially spaced and substantially parallel relation on the tube. 1 When a plurality of separated sets of spaced fin plates are to be supported each in continuous contacting relation, I provide a tube II such as' It is also possible by a simplified arrangement to obtain a single helical edged aperture in a fin plate, as shown in Figs. 12, 13, and 14. In accordance with this embodiment of my invention,

a fin plate 5| is provided with a single circular aperture 53 and a slit 55 is cut diametrically from one edge of the aperture about one radius distance toward one edge of the plate. The adjacent flexible points 51 and 59 thus provided are bent in opposite directions from the plane 'of the plate, as shown in Flg..13. The portion of the fin plate 5| on the side of the aperture opposite from the slit 51 is deformed into two spaced and substantially parallel planes 60 and 62, as shown more clearly in Fig. 14. The edges of the aperture 53 are thus distorted to substantially helical or spiral conformation. Along the edges of the aperture 53 on opposite sides of the slit 51, "annular portions 54 are flattened or deformed back to positions substantially parallel to the main plane of. the plate 5| whereby they are perpendicular to a supporting tube and freely enter its grooves. Although only a single aperture 53 is shown in the square plate ii, the latter may be of elongated rectangular or other conformation to provide a plurality of such helically edged apertures to receive as many grooved tubes as desired.

Fin plates of this conformation are guided upon and into the helical grooves of tubes, ll similarly to the fin plates previously described. Such an assembly of plates on an unexpanded tube is shown in the enlarged Fig. 15, and a rear view thereof is shown in Fig. 16. After the plates 5| have been assembled on the grooves,

the side walls of the grooves are collapsed together to grip the edges of the plate apertures.

This is accomplished by expanding the tube diametrically and shrinking it axiallyin the manner previouslydescribed whereby the side walls of the groove l3 grip the sides of the edges of -the apertures 53, and the bottom abuts the inturned edges ,andthe plates 5| are firmly secured thereon in efilcient thermal coupled relation.

In accordance with another embodiment, the principle of my invention may be utilized for supporting a plurality of plates 63 such as disk cut-" ters, condenser plates or the like in parallel spaced relation upon a tubular supporting member 64,

as shown in Fig. 17. For this purpose, I provide annular grooves 65 around the tube 64 and spaced axially along the outer surface thereof. The plates 63 have circular apertures of such a size that they fit loosely over the outer diameter of the tube 64. The plates are slipped on over the tube until they rest in their respective grooves i3 "after which the tube is expanded to bring the bottoms of the grooves into snug abutting engagement with the inner edges of the disk aper-' aivaeea tageously made, as shown in Figs. 18 and 19, with the tube receiving apertures 3 arranged in adjacent parallel-rows. To provide a rigid and thermally eflicient relation, the apertures 3 in each row are preferably staggered relative to the apertures in the adjacent rows for receiving tubes which are disposed in similar staggered relations.

Slits 5 are out between adjacent pairs of apertures l, as in the first embodiment of fin plate, shown in' Fig. 1. To make helically edged apertures, the adjacent pairs of plate tabs 1 and I thus provided are bent outwardly in opposite directions and the plate is distorted to provide parallel oii'set portions on opposite sides of the row of apertures. As shown, the offset portion of the fin platebetween the rows 'of apertures 3 provides a continuous aligned surface 69. The portions ll of the plate above and below the rows of apertures are parallel to but ofiset from the intermediate portion, and they are in alignment with each other, as shown in Fig. 19. The plate tabs 1 of each row, which are directed toward each other, are distorted to the left and the tabs l-which are directed away from each other are bent to the left of the plate as shown in Fig. 19.

It will be seen that I have provided a simple .and improved method of and apparatus for assembling and securing a plurality of fin plates upon a grooved tube in spaced apart continuous tube engaging relation in a simple convenient manner which provides improved mechanical strength and increased thermal efilciency while eliminating the necessity for auxiliary fastening accessories and operations.

Aside from the specific embodiment of the invention herein shownand described, it will be understood that various details of the construction may be altered or omitted without departing from the spirit and scope of the invention as disclosed and claimed, and that I do not desire to limit the invention to the exact constructions herein set forth. 7

. I claim:

1. The method of assembling and securing fin plates in spaced relation upon a pair of reversely threaded helically grooved tubes which comprises, providing a pair of spaced tube receiving apertures in each fin plate, slitting each'plate between the pair of apertures and deforming the separated tabs in opposite directions from the plane of the plates for distorting the edges of each pair of apertures to relatively reverse helical conformation, inserting said tubes in spaced relation in said spaced apertures, turning said tubes simultaneously in reverse directions for threading the fin platesupon the tubes, and securing the inturned edges snugly in said grooves.

2. The method of assembling and securing fin plates in spaced relation upon a pair of reversely threaded helically grooved tubes as defined in claim 1, in which the step of securing the inserted edges of the fin plate apertures snugly in the grooves consists in, forcing through each tube a snug fitting expander having a substantially sharp shoulder around the leading edge to shave oil metal bulging into the tube from the bottom of the groove for drawing together the side walls of the grooves to grip the opposite sides of the fin plates adjacent the aperture while expanding the bottom wallsof the grooves to abut the inserted edges of the plate apertures.

3. The method of assembling and securing fin plates in spaced relation upon a pair of reversely threaded helically grooved tubes which consists in, providing a pair of spaced tube receiving aperapertures to relatively reversed helical conformations, oil-setting the portions of the fln platesv on opposite sides of the pairs of apertures to deform the intermediate portion of the plate and make the apertures completely circular in projection, passing said reversely threaded tubes in spaced relation into said pairs of apertures, turning said tubes simultaneously in reverse directions for threading the fin plates evenly upon the threaded 5 tubes, and securing the plates in said grooves.

FLOYD J SIBLEY.

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