US2857661A - Axial finned tube banding head construction - Google Patents

Description

Oct. 28, 1958 E. BRUEGGER 6 AXIAL FINNED TUBE BANDING HEAD CONSTRUCTION Filed Aug. 30, 1954 4 Sheets-Sheet 1 Fig.1

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ATTORNEYS United States Patent 6 AXIAL FINNED TUBE BANDING IEAD CONSTRUCTION Ernest Bruegger, Canal Fulton, Ohio, assignor to The Grrscom-Russell Company, Massillon, ()hio, a corporation of Delaware Application August 30, 1954, Serial No. 453,022

13 Claims. (Cl. 29-202) My invention relates generally to improvements in devices for securing fin retaining bands on axial finned tubes. More specifically, my invention relates to a device for securing bands around axial finned tubes and at the same time seating the longitudinal fins in efficient heat transfer relationship in the grooves formed in the outer annular periphery of the tube. The axial finned tube banding head of the present invention is preferably for use in assembling the catalyst finned tubing construction described and claimed in my co-pending application, Serial No. 341,767, now Patent No. 2,778,610, issued January 22,1 957, and it is for use in assembling such construction of finned tubing that the present invention will be hereinafter described.

Certain prior constructions of finned tubes have used fins which were cast integrally with the tube, such fins extending axially and longitudinally of the tube. Other prior finned tube constructions have had the fins assembled on the outer peripheral surface of the tube by soldering, welding or brazing, either directly on the outer surface of the tube or in preformed grooves in the tube surface. Still other prior finned tube constructions have included fins which are inserted in preformed grooves in the outer tube surfaces with the fins being locked therein by rolling or beading the groove about the portion of the fin inserted in the groove.

Some of these prior constructions of finned .tubes have been satisfactory where the normal and usual plain surface fins are desired or required. None of these, however, are satisfactory for use with catalyst coated fins because of the damage or contamination of the catalyst coating caused by the necessary cooling mediums or tooling required to accomplish these assemblies.

My co-pending application, Serial No. 341,767, now Patent No. 2,778,610 dated January 22, 1957, discloses a construction of catalyst finned tube which has overcome the difficulties of these prior constructions. This catalyst coated finned tube construction includes axially extending catalyst coated fins received in preformed tapered grooves formed in the outer peripheral surface of a tube with bands spaced longitudinally along the tubing, circumferentially surrounding the outer extremities of the fins and retaining the fins assembled in the tube preformed grooves.

It is, therefore, a general object of the present invention to provide an axial finned tube banding head which completes the assembly of catalyst coated fins in preformed grooves in the outer peripheral surface of tubes and also secures bands circumferentially surrounding the ends of the finds to retain the fins in proper assembly with good heat transfer characteristics between the fins and tube.

It is a primary object of the present invention to provide an axial finned tube banding head which assembles catalyst coated fins and fin bands to tubes without damaging or contaminating the catalyst coating on the fins.

It is a further object of the present invention to provide an axial finned tube banding head which assembles 2,857,661 Patented Oct. 28, 1958 fins and fin bands to tubes in such a way that the fins may be easily removed and replaced when such is required.

It is still a further object of the present invention to provide an axial finned tube banding head which will assemble fins and fin bands to tubes without the necessity of the fins or bands being held to close production tolerances.

It is an additional object of the present invention to provide an axial finned tube banding head which will secure fin bands circumferentially surrounding axial fins mounted on tubes and at the same time will assemble the fins in efiective heat transfer relationship with the tube.

Finally it is an object of the present invention to provide an axial finned tube banding head which will finish assembling axial fins in preformed grooves in the outer peripheral surface of a tube and at the same time secure a band circumferentially surrounding the outer extremities of the fins in a quick and efficient manner with a minimum amount of production cost.

These and other objects are accomplished by the parts, constructions, arrangements, combinations and subcombinations comprising the present invention, the nature of which is set forth in the following general statement, a preferred embodiment of which-illustrative of the best mode in which applicant has contemplated applying the principlesis set forth in the following description and illustrated in the accompanying drawings and which is particularly and distinctly pointed out and set forth in the appended claims forming a part hereof.

The improved axial finned tube banding head construction comprising the present invention may be stated generally as including hold down means retaining a plurality of fins assembled partially received in grooves formed axially in the outer peripheral surface of a tube, tube guide means, fin guide means, primary clamp means, secondary clamp means, extension means on the secondary clamp means for receiving and retaining a fin band circumferentially surrounding the outer extremities of the fins, first pressure means selectively pressing the primary clamp means against the fin band forcing the fin hand against the outer extremities of the fins, and second pressure means selectively pressing the secondary clamp means against the fin band forcing the fin band inwardly etween the fins.

More specifically, the improved axial finned tube banding head construction comprising the present invention may be stated as including an adjustable hold down ring separate from the main banding head assembly retaining a plurality of fins assembled partially received in grooves formed axially in the outer peripheral surface of a tube, radially extending tube guide fingers equally spaced around the tube bearing against the outer peripheral surface of the tube between certain of the fins, a plurality of radially extending fin guide fingers equally spaced around the outer annular periphery of the tube received in the openings between the fins, radially extending primary clamp fingers radially aligned and spaced from the fins, the ends of said primary clamp fingers adjacent the ends of the fins being concave in configuration, radially extending secondary clamp fingers aligned midway between the fins having inner ends convex in configuration, said secondary clamp fingers extending radially inwardly to a diameter substantially greater than the outer diameter to which the fins extend, extension fingers on the inner ends of certain of the secondary clamp fingers extending radially inwardly a greater distance than said secondary clamp fingers for receiving and retaining a fin band circumferentially surrounding the outer extremities of the fins, primary clamp push rod connected to the outer ends of the primary clamp fingers and extending radially outwardly, secondary clamp push rods connected to the outer ends of the secondary clamp fingers and extending radially outwardly, first hydraulic cylinder means connected to the outer ends of the primary clamp push rods selectively forcing the primary clamp fingers against the fin band and the fin hand against the outer extremities of the fins, and second hydraulic cylinder means connected to the outer ends of the secondary clamp push rods selectively forcing the secondary clamp fingers against the fin band and the fin band inwardly between the fins.

By way of example, an embodiment of the improved axial finned tube banding head construction of the present invention is illustrated in the accompanying drawings forming a part hereof, wherein like numerals indicate similar parts throughout the several views, and in which:

Fig. 1 is a side elevation of an axial finned tube assembled with the banding head construction of the present invention;

Fig. 2, an end elevation of the axial finned tube shown in Fig. 1;

Fig. 3, a side elevation of the banding head comprising the present invention having an axial finned tube mounted therein;

Fig. 4, a fragmentary top view, part in elevation and part in section, of the banding head of the present invention;

Fig. 5, a fragmentary side view, part in elevation and part in section, looking in the direction of the arrows -5 in Fig. 4;

Fig. 6, a fragmentary side view, part in elevation and part in section, looking in the direction of the arrows 6-6 in Fig. 4;

Fig. 7, a fragmentary top view of the hold down ring looking in the direction of the arrows 7--7 in Fig. 5;

Fig. 8, a fragmentary top view of the fin guide finger assembly, looking in the direction of the arrows 8-8 in Fig. 6;

Fig. 9, a top elevation of the primary clamp fingers;

Fig. 10, a side elevation of the primary clamp fingers;

Fig. 11, a top elevation of the secondary clamp fingers without the extension fingers;

Fig. 12, a side elevation of the secondary clamp fingers without the extension fingers;

Fig. 13, a top elevation of the secondary clamp fingers with the extension fingers;

Fig. 14, a side elevation of the secondary clamp fingers with the extension fingers; and

Fig. 15, a section view taken transversely through the axial finned tube shown in Fig. 1 with the fins in various stages of assembly.

The axial finned tube banding head construction comprising the present invention includes a fin hold down ring assembly generally indicated at 1, a tube guide assembly generally indicated at 2, a primary and secondary clamp assembly generally indicated at 3, a fin guide assembly generally indicated at 4 and a banding head support assembly generally indicated at 5, as shown in Figs. 3, 4, 7 and 8.

The fin hold down ring assembly generally indicated at 1 includes a hold down ring 6 which has an inner diameter substantially greater than the outer diameter of the finned tube assembly. Openings 7 are formed radially through the hold down ring 6 and extend completely radially through said ring. Openings 7 are equally spaced cireumferentially around the ring 6 and are equal in number to the number of fins on the finned tube assembly.

A threaded portion 8 is formed in each of the openings 7 extending from the outer diameter of the ring 6 inwardly, after which the openings 7 are formed into a straight cylindical portion 9, which portion 9 extends to the inner diameter of the ring 6. Thumb screws 10 are received in each of the threaded portions 8 of the openings 7 which thumb screws terminate at their inner ends in a reduced diameter portion 11, a conical or tapered portion 12 and a spherical or ball portion 13.

The fin seats 14 are received in the cylindrical portion 9 of the openings 7. These fin seats 14 are slidably received in the openings 7 and have a diameter slightly less than the cylindrical portion 9 of the openings 7.

The outer ends of the fin seats 14 engage the ball portions 13 of the thumb screws 11 by mean of transverse slots 15 which are comprised of cylindrical portions 16 and lip portions 17. The cylindrical portions 16 are of a diameter slightly greater than the diameter of the ball portions 13 of the screws 10, while the lip portions 17 extend slightly inwardly towards the conical portions 12 of the screws 10, so that the openings of the slots 15 are slightly less than the outer diameter of the ball portions 13 of the screws 19.

Thus, before the thumb screws 10 and the fin seats 14 are assembled in the hold down ring 6,.the ball portions 13 of the screws 19 are engaged in the cylindrical portions 16 of the transverse slots 15 from either end of said slots. The screws 10 and the fin seats 14 are then assembled in the ring 6. Since the transverse slots 15 are of less width than the outer diameter of the ball portions 13 of the screws 10, due to the lip portions 17, the screws 10 may rotate in reference to the fin seats 14 with the ball portions 13 rotating in the transverse slots 15, but the fin seats 14 must move radially or longitudinally with the screws 10.

The inner ends of the fin seats 14 have transverse slots 18 formed therein. The transverse slots 18 have a width slightly greater than the width of the fins 19 to be assembled to the tube 190, as shown in Fig. 7. Thus, the fin hold down ring assembly 1 may be telescoped over the tube 19a and the fins 19 may be positioned in place. The fin seats 14 may be thereafter engaged with the fins 19 and the screws 10 may be rotated to move the fin seats 14 inwardly to engage the fins 19 in slots 18.

The primary and secondary clamp assembly generally indicated at 3 includes a cylinder ring 20, a clamp guide plate 21, cylinders 22, pistons 23, a primary manifold tube 24, a secondary manifold tube 25, push rods 26, a clamp guide ring portion 27, primary clamp fingers 28 and secondary clamp fingers 29.

The cylinder ring 20 has preferably an outer annular surface 39 and an inner annular surface 31 with a flange portion 32 extending inwardly at the lower edge of the ring 20 from the surface 31 with said flange also having preferably an inner annular surface 33. The clamping cylinders 22 are formed by the preferably circular openings 34 which extend radially inwardly between the outer annular surface 30 and the inner annular surface 31 of the cylinder ring 20.

Cylinders 22 are equally spaced cireumferentially around the cylinder ring 20 and are twice as great in number as the number of fins 19 to be assembled on the tube 19a. The circular cylinder openings 34 have threads formed therein, from the outer annular surface 30 of the cylinder ring 20 inwardly for a portion of their length, and the cylinder plugs 36 are received therein.

Cylinder plugs 36 are generally cylindrical in configuration and have threads 37 formed on their outer annular periphery for the major portion of their length. Thus, the cylinder plugs 36 may be threaded into the outer ends of the cylinders 22 and form a fluid tight seal at the outer end of the cylinder openings 34.

The pistons 23 are mounted in the cylinder openings 34 of the cylinders 22 and are generally cylindrical in configuration. Packing slots 38 are formed circumferentially in the outer annular periphery of the pistons 23 and the piston packings 39 are received therein. Piston paekings 39 are of any usual packing material and form a fluid tight seal against the annular sides of the circular opening 34, so that no fluid may pass by the pistons 23 and out the inner end of the cylinders 22.

The outer end surfaces 40 of the pistons 23 have projections 41 formed centrally therein, extending toward the cyl nder plugs 36. The inner d surfaces 42 of the cylinder plugs 36 also have a similar projection 43 formed centrally therein, extending toward the pistons 23. Thus, when the cylinder plugs 36 are threaded in the cylinder openings 22, and the pistons 23 have moved radially outwardly to their outermost positions, the projections 41 and 43 will abut each other limiting any further outward movement of the pistons 23. This retains the cylinder plugs 36 and the pistons 23 in spaced apart relationship, thereby forming the openings 44.

Primary cylinder entry ports 45 are formed transversely through the top sides of the cylinders 22 in every other cylinder around the circumference of the primary and secondary clamping assembly, and secondary cylinder entry ports 46 are formed similarly through the lower sides of the alternate cylinders. The cylinders that have the entry ports 45 formed through their top sides are used to actuate the primary clamp fingers 28, and the cylinders that have the entry ports 46 formed through their lower sides actuate the secondary clamp fingers 29, as will be hereinafter described. The entry ports 45 form passages between the openings 44 in the cylinders 22 and the inner confines of the primary manifold tube 24, while the entry ports 46 form passages between the openings 44 in the cylinders 22 and the confines of the secondary manifold tube 25.

The primary manifold tube 24 is mounted by preferably welding indicated at 47 to the top surface 48 of the cylinder ring and, as before stated, is connected to the openings 44 in the cylinders 22 through the entry ports 45. The secondary manifold tube is mounted by preferably welding indicated at 49 to the lower surface 50 of the cylinder ring 20, and also, as before stated, is connected to the openings 44 of cylinders 22 through the entry ports 46.

The primary manifold tube 24 and the secondary manifold tube 25 extend circumferentially around the top surface 48 and the lower surface 50 of the cylinder ring 20 to form solid ring-like tube members. The primary manifold tube 24 is provided with hydraulic fluid supply and exhaust connections 51, while the secondary manifold tube 25 is provided with hydraulic fluid supply and exhaust connections 52. Thus, the hydraulic fluid pressures to the manifold tubes 24 and 25 may be separately controlled.

The clamp guide plate 21 abuts and overlaps the flange 32 extending from the lower surface of the cylinder ring 20. This guide plate 21 extends inwardly towards the center of the banding head and has a ring-like configuration. A cutout 53 is formed circumferentially around the lower surface 54 of the guide plate 21 and extends from the outer annular periphery 55 of the guide plate 21 inwardly, as shown in Figs. 5 and 6. The inner annular surface 33 of the flange 32 engages against the inner side 56 of the cutout 53, so that the guide plate 21 abuts the inner surface 33 of the flange 32 at this point, and then extends over and abuts the top surface of the flange 32.

A push rod guide and spring retaining ring 57 is mounted on the top surface 58 of the guide plate 21 and extends from the outer annular periphery 55 of the guide plate 21 inwardly, as shown in Figs. 5 and 6. Retaining ring 57 has spring receiving openings 59 and push rod openings 60 formed radially therethrough equally spaced circumferentially around ring 57 and axially and radially aligned with pistons 23 and cylinders 22.

The spring openings 59 extend from the outer annular periphery 61 of the retaining ring 57 inwardly, and the openings 60 extending from the inner ends or surfaces 62 of the openings 59 inwardly to the inner annular periphery 63 of the retaining ring 57. The openings 59 and 60 are all circular openings with the openings 59 being of substantially greater diameter than the openings 60. Openings 59 also extend partially into the top surface 58 of the guide plate 21, as indicated at 64.

Preferably cap screws 57a, equally spaced at intervals around the circumference of the ring 57, retain the ring 57, the cylinder ring 20 and the clamp guide plate'21 in assembled position. Bolts 57a are received through the flange 32 of the cylinder ring 20, the outer portion of the clamp guide plate 21 and are threaded into the ring 57 as shown in Fig. 5.

The push rod guide and spring retaining ring 65 is mounted on the upper surface 58 of the guide plate 21 and has an inner annular periphery 66 and an outer annular periphery 67. Openings 68 are formed radially through the retaining ring 65 and are equally spaced around the circumference of the retaining ring 65. Openings 68 in the retaining ring 65 are also all in radial and axial alignment with the pistons 23 and the cylinders 22.

The push rods 26 are preferably cylindrical in configuration being circular in cross section and extend from the inner surface 69 of the pistons 23 through the openings 59 and 60 of the retaining ring 57 and the openings 68 in the retaining ring 65. The inner ends of the push rods 26 are spaced from the inner annular periphery 66 of the retaining ring 65. The piston return springs 70 are preferably helical springs and surround the push rods 26 and abut the inner surfaces 69 of the pistons 23 at their outer ends, and are received in the openings 59 and abut the inner surface 62 at their inner ends.

The preferably helical push rod return springs 71 surround the push rods 26 and abut the seat washer 72 at their inner ends, which washer 72 abuts the outer surface67 of the retaining ring 65. A ring of brazing material 73 is fused to the outer periphery of the push rods 26 spaced outwardly from the retaining ring 65 and inwardly from the retaining ring 57. The outer end of the push rod return spring 71 abuts this brazing material 73, thus, retaining the spring 71 between the washer 72 and the braze material ring 73.

Transverse slots 74 are formed on the inner ends of the push rods 26 which slots 74 extend from the inner ends of the push rods 26 outwardly. The fascinating holes 75 are also formed transversely through, and spaced from the ends of the push rods 26, and extend preferably perpendicularly to the transverse sides of the slots 74. The outer ends of the primary clamp fingers 28 are formed of a lesser lateral width, as indicated at 76, from their outermost ends extending inwardly.

The width of the portion 76 is slightly less than the width of the slots 74 so that the portion 76 of the primary clamp fingers 28 may be received in the slots 74 formed in the inner ends of the push rods 26. A transverse opening 77 is formed through the portion 76 in direct alignment with the openings 75 and cotter keys 78 may be received through the openings 75 and the openings 77. Thus, the primary clamp fingers 28 may be pivotally connected to certain of the push rods 26.

The secondary clamp fingers 29 have the same width throughout their lengths, which width is slightly less than the width of the slots 74 in the push rods 26. The outer ends of the secondary clamp fingers 29 may be received engaged in the slots 74 of certain of the push rods 26.

The openings 79 are formed transversely through and spaced from the outer ends of the secondary clamp fingers 29 with these openings 79 being in direct alignment with the openings 75 in the push rods 26. Other cotter keys 78 may be received through the openings 75 in the push rods 26 and the openings 70 in the secondary clamp fingers 29 so that the secondary clamp fingers 29 may be pivotally mounted to certain of the push rods 26.

As before stated, the push rods 26 are of a number equal to twice the number of fins 19 to be assembled to the tube 19a, and the push rods 26 are connected alternately to primary clamp fingers 28 and secondary clamp fingers 29 around the circumference of the banding head. Thus,

7 the primary clamp fingers 28 and the secondary clamp fingers 29 are spaced alternately around the tube 19a.

Primary clamp fingers 28 are connected to push rods 26 in radial alignment with the outer ends of the fins l9 and the secondary clamp fingers 29 are connected to push rods 26 in direct radial alignment with the midpoints between the fins 19. The innermost end surfaces 28a of the primary clamp fingers 28 are concave in configuration as best seen in Figs. 9 and 10, while the innermost end surfaces 29a of the secondary clamp fingers 29 are convex in configuration as best seen in Figs. ll and l2, for purposes to be hereinafter described.

The clamp guide plate 21 is of a greater height extending from its inner end for a distance outwardly, forming a guide ring portion 27. Guide slots 80 and 80a are formed radially through the guide ring portion 27 and extend from the inner annular periphery 81 of the guide plate 21 to the outer annular periphery 82 of the guide ring portion 27.

Slots 80 are in direct radial alignment with the secondary clamp fingers 29 and are of a width slightly greater than the fingers 29. Slots 80a are in direct radial alignment with the primary clamp fingers 28 and are of a width slightly greater than the width of the fingers 28. Slots 80 and 80a extend from the top of the guide ring portion 27 to the top surface 58 of the guide plate 21.

Thus, the inner ends of the primary clamp fingers 28 and the secondary clamp fingers 29 are received in the slots 80a and 80 respectively of the guide ring portion 27. The primary clamp fingers 28 and the secondary clamp fingers 29 extend inwardly to within a distance of the inner annular periphery 81 of the guide ring portion 27 of the guide plate 21 with the exception of certain of the secondary clamp fingers 29b as shown in Figs. 13 and 14.

Preferably about every eighth secondary clamp finger 29b has a band retaining extension 83 formed thereon, extending past the inner annular periphery 81 of the guide ring portion 27 for a distance inwardly from this inner periphery 81. These band retaining extensions 83 are of less height than the secondary clamp fingers 29b so that a band retaining surface 84, and a secondary clamping surface 85 are formed.

The tube guide assembly, generally indicated at 2, includes a clamp finger guide ring portion 86, a tube guide ring mounting portion 87 and tube guide fingers 88. The lower surface 89 of the clamp finger guide ring portion 86 abuts the top surface 90 of the clamp guide ring portion 27 of clamp guide plate 21. The lower surface 89 of the guide ring portion 86 extends outwardly for a distance slightly beyond the outer annular periphery 82 of the clamp guide ring portion 27, after which is formed the lower surface portion 91 on the guide ring portion 86 extending outwardly and spaced from the top surface 58 of the clamp guide plate 21.

The lower surface portion 91 terminates outwardly in a lower surface portion 92 which portion 92 abuts the top surface 58 of the clamp guide plate 21. This surface 92 extends outwardly to the outer annular periphery 93 of the tube guide assembly 2.

The top surface of the guide ring portion 86 includes an upwardly tapered portion 93', a fiat portion 94 and a downwardly tapered portion 95, as shown in Figs. and 6. The downwardly tapered portion 95 terminates inwardly at the inner annular periphery 96 of the guide ring portion 86. Tube guide ring mounting portions 87 extend upwardly from the flat portion 94 and are preferably four in number equally spaced circumferentially around the tube guide assembly 2.

A radially extending groove 97 is formed through each of the spaced mounting portions 87. The tube guide fingers 88 are received in the slots 97, one through each of the mounting portions 87. Pins 98 are received through the mounting portions 87 near their outermost edge and also through the tube guide fingers 88 near their outer ends, thereby pivotally mounting the tube guide fingers 88 in the mounting portions 87.

The slots 97 extend from slightly below the top surface flat portion 94 of the guide ring portion 86 to the top edge 99 of the mounting portion 87. Also, the lower outer corner of the tube guide fingers 88 are slightly radiused as indicated at 100. Thus, the tube guide fingers 88 may be pivoted around the pins 98 so that their inner ends swing in a radius away from the tube 19a.

The guide slots and 80a also extend radially through the clamping finger guide ring portion 86 so that the guide ring portion 86 surrounds and is spaced from the primary clamp fingers 28 and the secondary clamp fingers 29. In this way the clamp fingers may move reciprocally therethrough, but yet, the guide ring portion 86 aids in guiding them.

The tube guide assembly 2 is retained in position abutting the top surface 58 of the clamp guide plate 21 and the top surface of the clamp guide ring portion 27 by preferably bolts 101. Bolts 101 are preferably threaded through the clamp guide ring plate 21 and are positioned at equally spaced intervals circumferentially around the tube guide assembly 2.

Thus, hydraulic fluid may be admitted into the primary manifold tube 24 through the connections 51 and may pass through the primary cylinder entry ports 45. This will force certain of the pistons 23 against the push rods 26 connected to the primary clamp fingers 28 which push rods 26 will move radially inwardly, thereby forcing the primary clamp fingers 28 radially inwardly. As the push rods 26 move radially inwardly, the springs 70 and 71 will be compressed.

As hydraulic fluid is permitted to exhaust from the primary manifold tube 24, the springs 70 will force the pistons 23 radially outwardly until the projections 41 on the pistons 23 abut the projections 43 on the cylinder plugs 36. At the same time, the springs 71 will force the push rods 26 radially outwardly and cause the primary clamp fingers 28 to move radially outwardly.

The results of admitting and exhausting hydraulic fluid to and from the secondary manifold tube 25 are similar, with the exception that the hydraulic fluid enters certain other cylinders 22 through the secondary cylinder entry ports 46, and the secondary clamp fingers 29 will be moved radially inwardly and outwardly.

The fin guide assembly generally indicated at 4 includes a fin guide ring 102, a fin guide projecting portion 103 and fin guide fingers 104, as seen in Figs. 4, 5, 6 and 8. The stop surface 105 of the fin guide ring 102 abuts the lower surface 54 of the clamp guide plate 21 and is mounted thereto by means of preferably bolts 106 equally spaced around the circumference of the fin guide ring 102. Bolts 106 are received in countersunk holes 107 formed parallel to the axis of the fin guide ring 102 with said bolts being threaded into the clamp guide plate 21, retaining the fin guide ring 102 in position.

The inner annular periphery of the fin guide ring 102 is of slightly greater diameter than the inner annular periphery 81 of the clamp guide plate 21 and the clamp guide ring portion 27. The fin guide ring projecting portion 103 extends radially inwardly from the inner periphery 108 of the fin guide ring 102 and is of a height less than the total height of the fin guide ring 102. The inner annular periphery 109 of the portion 103 is of slightly greater diameter than the outside diameter described by the outer extremities of the fins 19 mounted on the tube 19a.

The fin guide fingers 104 extend radially inwardly from the inner periphery 109 of the projecting portion 103. Fingers 104 are equally spaced around the inner periphery 109 of the projecting portion 103, and are of a number equal to the number of fins 19. When in operative position, the fingers 104 project radially inwardly between the fins 19, as best seen in Fig. 4, with the arcuate ends of the fingers 104 spaced from the outer pe- 9 ripheral surface of the tube 19a and with the longitudinal sides 111 slightly spaced from the longitudinal sides of the fins 19.

Thus, the fin guide fingers 104 serve to guide the fins 19 to properly position these fins 19 around the outer peripheral surface of the tube 19a. The fingers 104 do not, however, wedge the fins 19 therebetween and therefore do not damage any catalyst coating or the like that may be on the outer surface of the fins 19.

The main portion of the banding head assembly which includes the tube guide assembly, generally indicated at 2, the primary and secondary clamp assembly, generally indicated at 3 and the fin guide assembly generally indicated at 4 is assembled in working position by means of the banding head support assembly 5. The banding head support assembly is comprised of clamps indicated at 112 and longitudinally extending support members 113.

The support members 113 are preferably steel channel members and are of a sufficient longitudinal length so that the clamp members 112 are supported a sufiicient distance from a horizontal floor surface, thereby supporting the banding head a sufficient distance above a floor, so that the tube 190 may be received centrally therethrough, and the banding head be in proper position to assemble the first band.

The clamp members 112 include longitudinally extending portions 114, top laterally extending portions 115, bottom laterally extending portions 116, top downwardly extending clamp portions 117 and bottom upwardly extending clamp portions 118. The longitudinally extending portions 114 are mounted within the channel shaped support members 113 and abut the inner surface 119 of the support members 113 at their outer surfaces 120.

Portions 114 extend above the upper ends of the support members 113 and the outer ends of the top and bottom laterally extending portions 115 and 116 abut the upper and lower ends of the longitudinally extending portions 114- so that a generally channel shaped member is formed, as best seen in Fig. 6. Also as seen in Fig. 6, the top downwardly extending clamp portions 117 abut the end surfaces at either end of the portions 114 and 115 and extend inwardly the length of the lateral portions 115.

Bottom upwardly extending clamp portions 118 are similar in configuration to clamp portions 117 and are mounted at he bottom portion of the longitudinal portion 114 and abut the ends of the longitudinal portion 114 and the bottom laterally extending portions 115. Clamp portions 118 are, however, positioned extending upwardly instead of downwardly. Arcuate manifold tube engaging slots 121 are formed near the inner ends of the clamp portions 117 and open downwardly, while the arcuate manifold tube engaging slots 122 are formed near the inner ends of the clamp portions 118 and open upwardly.

The clamp members 112 are preferably held in assembled position by the bolts 123, so that the manifold tube engaging slots 121 engage the outer surface of the primary manifold tube 24, and the tube engaging slots 122 engage the secondary manifold tube 25, thereby engaging the manifold tubes 24 and 25 at either end of the clamp members 112, and in this way retaining the banding head in proper position for the banding operation.

The tube 19a which is to have the fins 19 mounted thereon and banded in place, has axially extending grooves 124 formed in its outer peripheral surface at equally spaced intervals around the circumference of the tube with these grooves being of a number equal to the number of fins 19 to be assembled thereon. Grooves 124 preferably have inwardly tapered sides with their bottom widths being greater than their top opening widths and with these bottom widths being less than the widths of the fins 19. Thus, the fins 19 may be received partially in the grooves 124, but pressure is required to force the fins 19 to the bottom of the grooves 124.

The bands 125 to be assembled circumferentially surrounding the outer extermities of the fins 19 and retaining the fins 19 in the grooves 124 may be circular in cross section, but are preferably preformed so as to have a corrugated cross section with the peaks of the corrugations registering with the outer extremities of the fins 19 and with the valleys 127 of the corrugations registering between the outer extremities of the fins 19. The preformed band 125 before assembly have a diameter at the peaks 126 of the corrugations greater than the outer diameter described by the outer extremities of the fins 19 when the fins 19 are partially received in the grooves 124, so that he bands 125 may be slidably received over the partially assembled fins 19 before the assembly operation.

in preparation for the banding operation, the banding head assembly is preferably horizontally supported above a floor surface by means of the support assembly generally indicated at 5, as before described. The tube 190 is received vertically and centrally through the banding head assembly so that it is surrounded by the tube guide assembly 2., the primary and secondary clamping assembly 3 and the fin guide assembly 4, as shown in Fig. 3.

As the tube 1% is received through the banding head,

the tube guide fingers 88 may pivot around the pins 98, so as to allow free movement of the tube 19a therethrough.

A number of preformed corrugated bands 125 are then telescoped over the upper end of the tube 19a, with the number of bands being received thereon being the number to be assembled over the length of one of the tubes 19a. Also, the fin hold-down ring assembly 1 is then telescoped over the upper end of the tube 19a with the ring 6 having the thumb screws 10 threadably retracted so that the fin seats 14 are retracted into the cylindrical opening portions 9 of the ring 6.

The uppermost end of the tube 19a has the threads 128 formed thereon, and the support ring 129 is threadably engaged with the threads 128. The support ring 129 has a U-shaped yoke 139 mounted thereon, which yoke 130 projects upwardly and extends over the upper end of the tube 19a. Thus, with the support ring 129 assembled in place on the upper end of the tube 19a, a hoist means (not shown) may be engaged with the yoke 130 and support the tube 1% in a vertical position at any desired height in relation to the banding head.

The tube 19a, having the axially extending grooves 124 formed in its outer peripheral surface, is positioned vertically so that the primary and secondary clamping assembly 3 i axially aligned with the point on the tube 19a, at which the first band 125, will be assembled thereon. The

tube guide fingers 88 of the tube guide assembly 2 are.

then placed in their horizontal position so that the ends of these guide fingers 88 abut the outer peripheral surface of the tube 19a.

Thus, the tube guide fingers 88 and the fin guide fingers 104 of the fin guide assembly 4 retain the tube 19a in a vertical position so that the longitudinal axis of the tube 19a is perpendicular to the longitudinal axes of the primary and secondary clamp fingers 28 and 29, push rods 26 and pistons 23.

Pins 19, which have preferably been catalyst coated, are then threaded from below the banding head through the fin guide assembly 4 between the fin guide fingers 104 so that their upper ends are spaced from the top of the banding head and their inner extremities are partially received in the tapered grooves 124 in the position shown at 131 in Fig. 15. The preformed corrugated bands 125 that had been previously assembled on the tube 19a, are then telescoped around the outer extremities of the partially assembled fins 19.

The fin hold-down ring assembly 1 is also telescoped over the upper ends of the fins 19 and positioned as shown in Fig. 3. That is, the thumb screws 10 are threaded into the threaded portion 8 of the hold-down ring assembly 1, thereby forcing the fin seats 14 to engage over the outer extremities of the fins 19 by receiving the fins 19 in the slots 18. The fin hold-down ring assembly 1 thereby retains the fins 19 partially assembled in the tapered grooves 124 of the tube 19a prior to the first band 125 being assembled in place.

Next, the tube guide fingers 88 are again pivoted around the pins 98 to allow the first band 25 to move downwardly after which the first band 125 is dropped into engagement with the band retaining su'siazrc 84 cf the band retaining extension 83 formed on certain of the secondary clamp fingers 2%, as best seen in Fig. 5. The band 125 is positioned so that the peaks 126 of the corrugations register with the outer extremities of the fins 19 and the valleys 127 of the corrugations are centrally located between the fins 19. The tube guide fingers 88 are then replaced to their horizontal position abutting the outer peripheral surface of the tube 19a.

o Thereafter, hydraulic fluid is admitted through the primary manifold supply and exhaust connections 51 a any desired pressure into the primary manifold tube 24. The hydraulic fluid under pressure passes from the manifold tube 24, through the primary cylinder entry ports 45 and into the cylinders 22 which are connected to the primary clamp fingers 28. Thus, hydraulic fluid pressure is exerted against the pistons 23 moving the pistons radially inwardly towards the tube 191: and forcing the push rods 26 and the primary clamp fingers 28 radially inwardly.

As the primary clamp fingers 28 move radially inwardly, their concave ends engage the peaks 126 of the corrugated band 125 forcing the peaks 126 against the outer extremities of the fins 19 and causing the fins 19 to be forced to the bottom of the tapered grooves 124 formed in the outer peripheral surface of the tube 19a. Since hydraulic fluid pressure is used, this provides a resilient pressure forcing the primary clamp fingers 28 in wardly so that band 125 and fins 19 will be moved inwardly until a predetermined resistance, substantially equal to this resilient pressure, is exerted radially outwardly by band 125 and fins 19.

After this part of the assembly has taken place, bydraulic fluid under the same or any other desired pressure is admitted through the secondary manifold supply and. exhaust connections 52 into the secondary manifold tube 25. The hydraulic fluid passes from the secondary manifold tube 25, through the secondary cylinder entry ports 46 and into the cylinders 22 that are connected to the secondary clamp fingers 29. This exerts fluid pressure against the pistons 23 that are connected to the secondary clamp fingers 29 and forces the push rods 26 radially'inwardly towards the tube 19a and thereby forces the secondary clamp fingers 29 against the valley portions 127 of the band 125.

The convex ends of the secondary clamp fingers 29 engage the valley portions 127 of the band 125 forcing these valley portions 127 radially inwardly between the sides of the fins 19. This reshapes the corrugated ring 125 so that the peaks 126 of the corrugations firmly and permanently engage the outer extremities of the fins 19. Thus, the fins 19 are totally engaged and seated in the tapered grooves 12 in the position indicated at 132 in Fig. 15, and the corrugated ring 125 is permanently positioned engaged over the outer extremities of the fins 19 as shown in Fig. 2, holding the fins so assembled to the tube.

Again, since hydraulic fluid pressure is used, this provides a resilient pressure forcing the secondary clamp fingers 29 inwardly so that band 125 will be moved inwardly between fins 19 until a predetermined resistance, substantially equal to thi resilient pressure, is exerted radially outwardly by band 125.

The hydraulic fluid under pressure is then exhausted coating on the fins.

from the primary and Secondary manifold tubes 24 and 25 through the supply and exhaust connections 51 and 52, respectively, thereby allowing the hydraulic fluid to flow out of the cylinders 22 through the ports 45 and 46. Thus, fluid pressure is no longer exerted on the pistons 23, allowing the piston return springs 70 to move the pistons 23 radially outwardly away from the tube 190, until the projections 41 on the outer ends 40 of the pistons 23 abut the projections 43 on the inner ends 42 of the cylinder plugs 36. This causes the push rod return springs 7 3 to bear against the brazed rings 73, causing the push rods 26 to move radially outwardly away from the tube 19a, moving the primary and secondary clamp fingers 28 and 2 9 radially outwardly and disengaging them from the band 125.

Since the first band is permanently assembled in place, the tube 19a and the fins 19 are ready to have the second hand assembled in place. This operation is started by raising the tube guide fingers 88 upwardly so that they pivot around the pins 98. The hoist means (not shown) is then raised causing the tube 19a and the fins 19 to move vertically upwardly through the banding head until the primary and secondary clamp fingers 28 and 29 are radially aligned adjacent the point on the tube 19a and fins 19, at which the next band is to be assembled therearound.

A second band 125 is then moved downwardly so that it telescopes over the first band that has been permanently assembled and is received on the band retaining surface 84 of the band retaining extensions 83 formed on certain of the secondary clamp fingers 29b. The tube guide fingers 88 are then pivoted downwardly around the pins 98 so that the ends of the fingers 88 engage the outer peripheral surface of the tube 190. Thus, the tube 19a and the fins 19 are in position and ready for the second banding operation. This second banding operation and subsequent banding operations are performed in the same manner as the first banding operation, until all of the bands 125 have been permanently assembled in their respective positions spaced axially along the fin and tube assembly.

Although the banding head construction has been described and shown with the banding head in a horizontal position and the fins and tubes to be assembled in a vertically extending position, it should be understood that with slight modifications and the proper supports, this banding head construction described herein could be mounted and used in any position, for instance, with the banding head in a vertical position and the tube and fins to be assembled in a horizontal position.

Also, although the banding head construction has been described as using hydraulic pressure to actuate the pistons 23 connected to the primary and secondary clamp fingers 28 and 29, it is possible to substitute pneumatic pressure therefor, the important feature being that it is resilient pressure means. Still further, although the banding operations described herein have been for use with catalyst coated fins, the banding head of the present invention can be used advantageously to assemble many types of fins and tubes through the same general procedure.

Thus, the axial finned tube banding head comprising the present invention, and heretofore described, may be used to quickly and efficiently assemble catalyst coated fins without damaging or contaminating the catalyst Special tools are not required to force the fins into proper assembly and thereby cause damage to the catalyst coating. Nor are cooling liquids required since there is no heat involved in the assembly operation. In this way, damage or contamination of the catalyst coating on the fins is completely eliminated.

Further, by use of the device of the present invention, it is unnecessary to form the fins to close production tolerances. The banding head construction will properly assemble the fins on the tube and retain the fins in such assembly, despite minor variations in radial length of the fins, since the corrugated band is formed around the fins at whatever length they may extend by the resilient pressure means'forcing the band inwardly until a resistance equal to the resilient pressure is met. The width of the fins is somewhat critical, but still may vary slightly because of the wedging action of the tapered grooves into which the fins are assembled.

The quick and efiicient assembly is greatly aided by the end surface configurations of the primary and secondary clamp fingers 28 and 29. The concave end surfaces 28a of the primary clamp fingers 28 bear against the convex peaks 126 of the bands 125 so that the peaks 126 are properly shaped over the outer extremities of the fins 19. The convex end surfaces 29a of the secondary clamp fingers 29 bear against the concave valleys 127 of the corrugated bands 125 so that these valleys 127 will be further shaped in a concave configuration and thereby properly retain the peaks 126 against the outer extremities of the fins 19.

Because the fins 19 are received in tapered grooves 124 of the tube 19a, it is possible by use of the banding head construction comprising the present invention, to finish assemble the tube 19 in the tapered grooves 124 in the same operation that the peaks 126 of the corrugated bands 125 are shaped over the outer extremities of the fins 19. Thus, the time for assembly is greatly decreased resulting in production time and cost being decreased. Further, during this assembly operation, the

fins 19 are placed in efficient heat transfer relationship with the tube 19a since they tightly wedge in the tapered grooves 124.

If at any time, it is necessary to remove the fins 19, such removal may be done with a minimum amount of time and cost and without damage to the tube 19a. It is only necessary to expand bands 125 away from the outer extremities of the fins 19 and thereby loosen and remove the bands 125. The fins 19 may then be quickly removed from their wedged position in the tapered grooves 124 since there is no radial force retaining them in the grooves 124.

Thus, an axial finned tube banding head construction has been provided which completes the assembly of catalyst coated fins in preformed grooves in the outer peripheral surface of tubes and also secure bands circumferentially surrounding the ends of the fins to retain the fins in proper assembly; which assembles catalyst coated fins and fin bands to tubes without damaging or contaminating the catalyst coating on the fins; which assembles fins and fin bands to tubes in such a way that the fins may be easily removed and replaced when such is required; which will assemble fins and fin bands to tubes Without the necessity of the fins or hands being held to close production tolerances; which will secure fin bands circumferentially surrounding axially extending fins mounted on the tubes and at the same time will assemble the fins in effective heat transfer relationship with the tube; and which will finish assembling axial fins in preformed grooves in the outer peripheral surface of a tube and at the same time secure a band circumferentially surrounding the outer extremities of the fins in a quick and efiicient manner with a minimum amount of production cost.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom, be-

cause such words are used for descriptive purposes herein, and are intended to be broadly construed.

Moreover, the embodiment of the improved construction illustrated and described herein is by way of example, and the scope of the present invention is not limited to the exact details of the construction shown.

Having now described the invention, the construction, operation and use of a preferred embodiment thereof,

14 and the advantageous new and useful results obtained thereby, the new and useful construction and reasonable mechanical equivalents thereof obvious to those skilled in the art are set forth in the appended claims.

I claim:

1. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, primary clamp means, secondary clamp means, extension means on certain of the secondary clamp means for receiving and retaining a fin band prior to assembly, and pressure means for pressing the primary clamp means against the fin band forcing the fin hand against the outer extremities of the fins and pressure means for pressing the secondary clamp means against the fin band forcing the fin band inwardly between the fins.

2. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, primary clamp means, secondary clamp means, extension means on certain of the secondary clamp means for receiving and retaining a fin band prior to assembly, first pressure means pressing the primary clamp means against the fin band forcing the fin hand against the outer extremities of the fins, and second pressure means pressing the secondary clamp means against the fin band forcing the fin band inwardly between the fins.

3. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including a tube guide ring circumferentially surrounding the other extremities of the fins, tube guide fingers connected to the tube guide ring extending radially inwardly in relation to the tube between certain of the fins and abutting the outer peripheral surface of the tube, fin guide means, primary clamp means, secondary clamp means, extension means on certain of the secondary clamp means for receiving and retaining a fin band in position prior to assembly, first pressure means pressing the primary clamp means against the fin band forcing the fin hand against the outer extremities of the fins, and second pressure means pressing the secondary clamp means against the fin band forcing the fin band inwardly between the fins.

4. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, a fin guide ring circumferentially surrounding the outer extremities of the fins, fin guide fingers connected to the fin guide ring and extending radially inwardly in relation to the tube between each of the fins, primary clamp means, secondary clamp means, extension means on certain of the secondary clamp means for receiving and retaining a fin band in position prior to assembly, first pressure means pressing the primary clamp means against the fin band forcing the fin hand against the outer extremities of the fins, and second pressure means pressing the secondary clamp means against the fin band forcing the fin band inwardly between the fins.

5. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, reciprocally movable primary clamp fingers extending radially in relation to the tube and having concave inner end surfaces, reciprocally movable secondary clamp fingers extending radially in relation to the tube and having convex inner end surfaces, extension means on certain of the secondary clamp fingers for receiving and retaining a fin band in position prior to assembly, first pressure means pressing the primary clamp fingers against the fin band forcing the fin hand against the outer extremities of the fins, and second pressure means pressing the secondary clamp fingers against the fin band forcing the fin band inwardly between the fins.

6. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, primary clamp means, secondary clamp means, extensions projecting radially inwardly in relation to the tube on certain of the secondary clamp means for receiving and retaining a fin band in position prior to assembly, first pressure means pressing the primary clamp means against the fin band forcing the fin band against the outer extremities of the fins, and second pressure means pressing the secondary clamp means against the fin band forcing the fin band inwardly between the fins.

7. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, reciprocally movable primary clamp fingers extending radially inwardly in relation to the tube, reciprocally movable secondary clamp fingers extending radially inwardly in relation to the tube, extension means on certain of the secondary clamp fingers for receiving and retaining a fin band in position prior to assembly, pressure cylinder means con nected to the primary and secondary clamp fingers for pressing the primary clamp fingers against the fin band forcing the tin band against the outer extremities of the fins and for pressing the secondary clamp fingers against the fin band forcing the fin band inwardly between the fins.

8. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including tube guide means, fin guide means, reciprocally movable primary clamp fingers extending radially inwardly in relation to the tube, reciprocally movable secondary clamp fingers extending radially inwardly in relation to the tube, extension means on certain of the secondary clamp fingers for receiving and retaining a fin band in position prior to assembly, push rods connected to each of the primary and secondary clamp fingers and extending radially in relation to the tube, and pressure cylinders connected to each of the push rods for pressing the push rods connected to the primary clamp fingers radially inwardly pressing the primary clamp fingers against the fin band forcing the fin band against the outer extremities of the fins and for pressing the push rods connected to the secondary clamp fingers radially inwardly pressing the secondary clamp fingers against the fin band forcing the fin band inwardly between the fins.

9. Axial finned tube banding head construction including radially extending tube guide fingers equally spaced circumferentially around the tube bearing against the outer peripheral surface of the tube between certain of the fins, a plurality of radially extending fin guide fingers equally spaced circumferentially around the tube received in the openings between each of the fins, reciprocally movable radially extending primary clamp fingers radially aligned and spaced from the fins, the ends of said primary clamp fingers adjacent the ends of the fins being concave in configuration, reciprocally movable radially extending secondary clamp fingers radially aligned midway between the fins and having inner ends convex in configuration, said secondary clamp fingers extending radially inwardly to a diameter substantially greater than the outer diameter to which the fins extend, extension fingers on the inner ends of certain of the secondary clamp fingers extending radially inwardly a greater distance than said secondary clamp fingers for receiving and retaining a fin band circumferentially surrounding the outer extremities of the fins, primary clamp push rods connected to the outer ends of the primary clamp fingers and extending radially outwardly, secondary clamp push rods connected to the outer ends of the secondary clamp fingers and extending radially outwardly, first hydraulic cylinder means connected to the outer ends of the primary clamp push rods for forcing the primary clamp fingers against the fin band and the fin band against the outer extremities of the fins, and second hydraulic cylinder means connected to the outer ends of the secondary clamp push rods for forcing the secondary clamp fingers against the fin band and the fin band inwardly between the fins.

10. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including reciprocally movable clamp fingers extending radially in relation to the tube and mounted for engagement with at least one fin band positioned surrounding a tube, extension means on certain of the clamp fingers for receiving and retaining a fin band prior to assembly, pressure means for pressing certain of the clamp fingers against a fin band forcing the fin band against the outer extremities of the fins, and pressure means for pressing certain other clamp fingers against the fin band forcing the fin band inwardly between the fins.

11. Axial finned tube banding head construction for assembling bands circumferentially surrounding axiallyextending fins mounted on the outer surface of a tube including a tube guide engageable with the tube for positioning the tube, fin guides positioning the fins on the tube outer surface, clamp means partially engageable with the bands radially outward of the fins and partially engageable with the bands radially outward of spaces between the fins, first resilient pressure means for pressing the part of the clamp means engageable with the bands radially outward of the fins radially inwardly until a predetermined resistance is exerted radially outward by the bands and fins, and second resilient pressure means for pressing the part of the clamp means engageable with the bands radially outward of spaces between the fins radially inwardly until a predetermined resistance is exerted radially outward by the bands.

12. Axial finned tube banding head construction for assembling bands circumferentially surrounding axiallyextending fins mounted on the outer surface of a tube including a tube guide engageable with the tube having the axially extending fins mounted thereon for positioning the tube, retaining means adapted for receiving and retaining a fin band in position surrounding the tube and fins prior to assembly, resilient pressure actuated clamp means partially engageable with the fin band radially outward of the fins for pressing the fin band radially inwardly against the fins until a predetermined resistance is exerted radially outward by the band and fins, and said resilient pressure actuated clamp means also being partially engageable with the fin band radially outward of spaces between the fins for pressing the fin band radially inwardly between the fins until a predetermined resistance is exerted radially outward by the band.

13. Axial finned tube banding head construction for assembling bands circumferentially surrounding axially extending fins mounted on the outer surface of a tube including a tube guide engageable with the tube for positioning the tube, a series of circumferentially spaced radially movable primary clamp members positioned for engagement with at least one fin band at locations on the fin band in substantial radial alignment with the outer extremities of the fins, a series of circumferentially spaced radially movable secondary clamp members positioned for engagement with at least said one fin band at locations on the fin band radially outward of spaces between fins, first resilient pressure means operably connected with the primary clamp members for pressing the primary clamp members against the fin band and forcing the fin band radially inwardly until a predetermined resistance is exerted radially outward by the band and fins, and second resilient pressure means operably connected with the secondary clamp members for pressing the secondary clamp members radially inwardly against the fin band and forcing the fin band radially inwardly between the fins until a predetermined resistance is exerted radially outward by the band.

References Cited in the file of this patent UNITED STATES PATENTS Tevander Nov. 18, 1913 Strong Apr. 19, 1921 Burr July 26, 1932 Fausset et a1. Sept. 25, 1945

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