US3580028A

US3580028A - Apparatus for producing external integral fins for tubing

Info

Publication number: US3580028A
Application number: US803895*A
Authority: US
Inventors: Frank F Walters
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1968-03-03
Filing date: 1968-03-03
Publication date: 1971-05-25
Anticipated expiration: 1988-05-25

Abstract

An improvement in apparatus for forming axially spaced integral helical fins on a length of tubing, the apparatus including a body member mounted within and interconnected to an outer housing which defines the outer surface of a tube finning head assembly. Journaled within the body member are a plurality of crescentshaped cams which operate a plurality of forming roll assemblies including tool support arbors. Supported on the arbors are a plurality of die means which define axially-spaced peripheral portions with grooves formed therebetween. The body member is made of heat-hardened steel, thereby increasing its wear resistance. The body member may be easily disengaged from the housing thereby expediting and reducing the cost of certain repairs.

Description

United States Patent [72] Inventor Frank F. Walters Syracuse, N.Y. I 21 1 Appl. No. 803,895 [22] Filed Mar. 3, 1968 [45] Patented May 25, 1971 [73] Assignee Carrier Corporation Syracuse, N.Y.

[54] APPARATUS FOR PRODUCING EXTERNAL INTEGRAL FINS FOR TUBING 4 Claims, 4 Drawing Figs.

[52] US. Cl 72/98, 72/100, 72/104 [51] Int. Cl B21h 3/12 [50] Field of Search 72/95, 96, 98, 100, 102,104, 238

[56] H References Cited UNITED STATES PATENTS 2,760,389 8/1956 Hill 72/104 3,296,845 1/1967 Prutton 3,379,042 4/1968 Brown, Sr.

ABSTRACT: An improvement in apparatus for forming axially spaced integral helical fins on a length of tubing, the apparatus including a body member mounted within and interconnected to an outer housing which defines the outer surface of a tube finning head assembly. Joumaled within the body member are a plurality of crescent-shaped cams which operate a plurality of forming roll assemblies including tool support arbors. Supported on the arbors are a plurality of die means which define axially-spaced peripheral portions with grooves formed therebetween. The body member is made of heat-hardened steel, thereby increasing its wear resistance. The body member may be easily disengaged from the housing thereby expediting and reducing the cost of certain repairs.

Patented May 25, 1971 2 Sheets-Sheet 1 INVENTOR. FRANK F. WALTERS.

AT TORNEY.

I Patented May 25, 1971 2 Sheets-Sheet 2 INVENTOR. FRANK E WALTERS.

dad/:

ATTORNEY.

APPARATUS FOR'PRODUCING EXTERNAL INTEGRAL FINS FOR TUBING BACKGROUND OF THE INVENTION This invention relates to the manufacture of integrally finned tubing, and more particularly it relates to an improved tube finning head assembly.

lntegral helical external fins are formed on lengths of tubing by subjecting the tubing to a circumferential rolling pressure radially inward against axially spaced peripheral portions of a tubing to extrude material from the wall of the tubing radially outward to form fins. The apparatus for forming fins on tubing generally include a plurality of forming roll assemblies which are precision spaced about the tube and are mounted to move toward the tube. Each forming roll assembly has die means mounted on a supporting arbor; the die means define axially spaced peripheral portions with grooves therebetween. The die means are commonly discs which are graduated in diameter and width to progressively form fins of the desired size and height.

Preferably, three forming roll assemblies are mounted with their axes essentially parallel to each other but spaced 120 apart. The axes of the roll assemblies are at a slight skew angle in the customary manner so the tube will be advanced through the apparatus and the fins will define a helical path about the tube. Radial movement of the roll assemblies into or out of engagement with the tube being finned is controlled by cams, each of the arbors being mounted in an associated cam. The cams are joumaled within mating bores disposed on the inner surface of a substantially cylindrical member, the outer surface thereof defining the outer periphery of the tube finning head assembly, the cylindrical member forming a housing'for the other components of the assembly. The bores establish the desirable skew angle for the axes of the roll assemblies.

Heretofore, it has been the practice to weld flanges on the opposed ends of a cylindrical pipe to form the housing. Prior to the welding operation, the pipe is machined to form the mating bores previously described above.

Several problems have arisen related to the above-described head assembly. The housing is fabricated from mild steel components to avoid severe problems in the welding operation. As a result, the inner surface of the housing will wear due to the rolling action of the cams thereon. The wearing of the mating bores will change the skew angle at which the axes of the roller assemblies are established. Furthermore, the cams will no longer have a close tolerance fit with their associated mating bores. This in turn will cause concomitant problems including incorrect alignment of the roller assemblies with the tube being finned.

Repairs of the above are costly since they require, in most cases, a complete boring out of the inner surface of the housing and the subsequent relining with metal so the necessary mating bores can be remachined on the inner surface. Alternatively, the cylindrical head assembly is discarded at a substantial monetary loss.

Furthermore, since a head assembly is a substantially heavy piece of equipment, in order to permit its removal from the finning machine, a crane or similar lifting apparatus is required. In addition, many pipes are connected to the outer surface of the head assembly for automatic operation and lubrication of the machinery. These pipes must be disconnected before the head assembly is removed, thereby further increasing the time in which a finning machine is inoperative when repairs, as described above, are being made.

Additionally, advances in the art have produced doublelead fins. The skew angle at which they axes of the roller assemblies are set for "double-lead" finning is approximately twice that of the angle when single-lead" finning is being done. To change from double-lead" to single-lead" or vice versa, an entire new head must be available with the mating bores machined at the proper skew angle. The duplication of head assemblies substantially increases the cost of a tube finning operation. Furthermore, the time in which the changeover fromone head to another can be done is substantially large for the reasons previously explained. Long idle periods for the machinery are very undesirable from a production viewpoint.

The object of the invention herein disclosed'is to alleviate or eliminate the problems discussed hereinabove. A new finning head assembly is described that is substantially easier and inexpensive to repair or to change from "single-lead" operation to double-lead" operation or vice versa. In addition, the present invention will require substantially less repair work since the mating bores on the inner surface of the head assembly will notrequire any repairs for a much longer period of time when compared to the mating bores previously described.

SUMMARY OF THE INVENTION The present invention discloses a new and improved finning head assembly. A body member comprising two substantially cylindrical plates, joined together in spaced apart relationship is mounted within a chamber of a substantially cylindrical member or housing defining the outer periphery of the head assembly. The housing and the body member are joined together so that the body member may be easily disengaged and removed from the housing. The mating bores for the cams previously described are machined on the inner surfaces of the plates of the body member.

As discussed hereinabove, one of the more severe problems associated with the finning head assemblies presently in use is wear of the internal mating'bores. The invention herein disclosed alleviates this problem by constructing the body member from heat-treated steel which hasconsiderably longer wear characteristics when compared to mild steel. By constructing the housing of the head assembly in the manner herein described, heat-treated steel may be thus utilized without introducing difficulties into the fabrication of the housing by welding methods. Only the outer surface of a cylindricalpipe will be welded to opposed end flanges to form the housing for the head assembly; therefore, the body member can be made from the heat-treated steel as is desirable.

The novel construction herein disclosed offers a further advantage since a single head assembly can be adjusted for varied skew angles merely by interchanging a prebored body member with the desired skew angle, for the body member mounted in the housing. This affords a substantial saving in both time and money when compared to the manner in which such a change might be effected with the head assemblies presently in use. i

As previously stated, at present a whole new assembly would have to be placedon the machine whenthe skew angle is to be changed. This would entail the use of lifting equipment, such as a crane, plus the necessity of either maintaining extra head assemblies or keeping the finning machine inoperative while the mating bores in the housing are rebored'to the desirable skew angle. With the improved assembly disclosed herein, the finning machine operator can manually place a new body member into the housing while the housing remains secured to the machine. A preferred embodiment would require merely the removal of a few bolts, and the old body member may be removed and the new member can then be mounted in its place.

The cost of spare body members is approximately one third the cost of the present head assembly housing. Thus, it is- BRIEF DESCRIPTlON OF THE DRAWING FIG. 1 is a perspective view of a head assembly housing now known to the art;

FIG. 2 is an exploded perspective view of the head assemblywhich is the subject of this invention;

FIG. 3 is an end view partially broken away of the novel head assembly mounted on a finning machine (not shown); and

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is diagrammatically represented by FIG. 2, FIG. 3, and FIG. 4 the novel finning head assembly herein disclosed, and for comparison thereto, FIG. 1 represents a finning head housing presently utilized in the art. In referring to the FIGS. like numerals will represent like parts.

Referring now to FIG. 1, there is perspectively shown the finning head housing now used in the art. The housing includes a substantially narrow-mouth cylindrical pipe 11. Welded at opposed ends 12 and 13 of the pipe 11 are flanges l4 and 15. The outer surface 16 of the housing 10 defines the outer periphery of the finning head assembly. Machined on the inner surface of the housing 10 are a plurality of bores 18. The bores 18 are machined at a skew angle for obtaining integral helical fins as desired on a length of tubing. The bores 18 will journal cams (not shown) which will actuate forming roll assemblies (not shown). A plurality of openings 17 are disposed on the flange 14 for receiving joining means for connecting the assembled finning head assembly to the finning machine. Suitable conduits for lubrication (not shown) will be connected to the housing 10 for automatic finning operation.

Now referring to FIGS. 2, 3, and 4, there is diagrammatically shown the novel finning head assembly herein disclosed.

A substantially wide-mouth cylindrical pipe 20 has

flanges

21 and 22 welded at opposed ends 23 and 24, the weldment forming a housing 25 for the finning head assembly. Two substantially

cylindrical plates

26 and 27 joined together in spaced apart relationship form a body member 28 to be disposed within the housing 25. The inner surface of the housing 25 will circumferentially surround the body member 28. The

plates

27 and 26 may be joined together by any wellknown means. As shown, the plates are held together by three

bolts

29, 30, and 31. In addition, a key 32 not only is used to position the

plates

26 and 27 relative to each other, but will also fit within an associated mating groove 33 on the inner surface of the housing 25, thus firmly positioning the body member 28 within the housing 25. Several cap screws 66 axially join the body member 28 to the housing 25. A plurality of bores 34 will be machined on the inner surface of the

plates

26 and 27. The bores 34 are machined at a slight skew angle so that a length of tube will be advanced through the apparatus and the integral fins therein formed will define a helical path about the tube.

A preferred embodiment will have three bores 34 machined as shown.

Mounted within the bores 34 are a plurality of crescentshaped cams 39. The cams 39 extend between the

plates

26 and 27 and are equispaced from each other. Integrally formed with the cam 39 is bearing housing portion 36, circumferentially joumaling bearings 40. Rotatably disposed within the bearing 40 is one end of a shaft 37 of a gear 38. The other end of the shaft 37 is similarly joumaled by bearings within end cap 36a. Gear 38 will cause the fins forming discs to rotate in a manner to be more fully described hereinafter. End cap 36a is connected to the cam 39 by connecting means such as cap screw 41. Thus the gear 38 is prevented from moving axially by the housings 36 and 36a.

Eccentrically joumaled within the cams 39 are an equal number of forming roll assemblies including arbors 42. Although there is only one forming roll assembly shown in FIG. 2, it should be understood that the number of assemblies will not be so limited. A preferred embodiment, as shown by FIG. 3, will have three assemblies. The assemblies 35 are connected to the cams 39 by keys 43. Thus, limited rotation of a cam 39 for a purpose to be later described will cause a corresponding movement in a forming roll assembly 35.

Supported on the arbors 42 are a plurality of die means 44 which define axially spaced peripheral portions with grooves formed therebetween. The die means 44 will be connected to the arbor to rotate therewith. A preferred embodiment has the die means 44 connected to the arbor shaft by key means 46. The key 46 will prevent any rotation of the die means relative to the arbor shaft. Journaling the arbor shaft are a plurality of bearings 47, contained within bearing housings 48 and 48a.

Formed integrally with one end of the arbor shaft is coupling member 49. It is to be understood that such member does not have to be formed integrally with the arbor shaft. The coupling member 49 joins the forming roll assembly to the gear 38. As is best shown in FIG. 4, the coupling member 49 fits into an opening machined into one end of the shaft 37 of the gear 38. The gear 38 will mesh with a main gear (not shown) which is driven by the finning machine motor. Rotation of the main gear will in turn rotate gear 38, thus rotating the forming roll assemblies as required to obtain the helical fin. A holding nut 50 will maintain the die means 44 in their axial positions on the arbor 42. Thrust washers and spacers may be used wherever necessary. The forming roll assemblies will be prevented from moving axially by means which shall be explained hereinafter.

Referring more particularly to FIGS. 3 and 4, there is shown an assembled finning head assembly mounted on a finning machine (not shown).

A control rod 51 (FIG. 3), controlled by means (not shown) such as air, is connected to the finning head assembly via yoke 52 and clevis 53. The control rod 51 acts as the driving means for automatic operation of the head assembly. As will hereinafter become clearer, movement of the control rod 51 will cause a corresponding radial movement of the die means 44 into or out of engagement with the tube stock being finned. Movement of the control rod 51 is transmitted by the yoke 52 and clevis 53 to a ring 54 movably mounted on the outer surface 68 of flange 22 of the housing 25 by cap screws 75. Mounted on ring 54 is a stop block 55 disposed between

adjustable stops

56 and 57 which are mounted on the housing 25. Stop block 55 and

adjustable stops

56 and 57 limit the rotation of the ring 54. Three

dogs

58, 59, and 60 are connected to the ring 54 to rotate therewith, via cam follower 61.

The

dogs

58, 59, and 60 are connected to an associated crescent-shaped

cam

39, 39a, and 39b by means of cap screws 63. It should be understood that the dogs and cams can be connected by any other means that afford easy disconnection when desired.

It is now readily apparent that movement of ring 54 will thereby rotate the earns 39, 39a, and 39b and cause a corresponding radial movement of the arbors 42, 42a, and 42b, eccentrically joumaled within the cams and connected thereto. The cams and their associated operating means thereby engage or disengage the die means 44 mounted on the arbors from the tube disposed radially between the die means.

As noted previously, the arbors and their associated die means are caused to rotate through the actuation of the gear member 38. A recess or relief 64 is made in the surfaces of the cams to accommodate the rotation of the die means.

A cover plate 67 will be connected to the outer surface 68 of flange 22 of the housing 25 by a plurality of cap screws 69. Disposed on the inner surface of plate 67 will be a plurality of angled shims 70. The shims 70 will maintain the

dogs

58, 59, and 60 in axial contact with the body member 28 and will prevent the crescent-shaped cams 39 from moving axially relative to the body member 28.

Retaining member 71 including stop 72 and spring loaded cap screw 73 will maintain the forming roll assemblies 35 in their axial positions within the crescent-shaped cams 39.

If it is desired to change the skew angle at which the bores 34 are machined, the entire housing need not be disengaged from the machine. Pin 74 i.:- removed disconnecting the control rod 51 from the clevis 53. The cover plate 67 is then disconnected from the housing. The dogs, cams, and forming roll assemblies can then be removed as a unit from the assembly. The movable ring 54 is then disconnected from the housing 25 by removing screws 75. Screws 66 are then removed and thebody member 28 is disengaged from the housing 25. A new body member, with the mating bores at the desirable skew angle, can then be inserted into the housing. The remainder of the parts are then reassembled and the finning operation can then continue. It is readily apparent that such an operation can be manually performed at a minimum stoppage in the firming process, thus alleviating the problems discussed hereinbefore.

While I have described and illustrated a preferred embodiment of my invention, it should be understood that my invention is not limited thereto, since it may be otherwise embodied within the scope of the following claims.

I claim:

1. Apparatus for forming axially spaced integral helical fins, said apparatus including a tube finning head assembly comprising:

l. a housing defining the outer surface-of said sembly;

2. a body member mounted within and interconnected to said housing, said body member being easily disconnected from said housing to be removed therefrom;

head as- 3. a plurality of cams joumaled within an equal number of mating bores formed within the inner surface of said body member;

4. a plurality of forming roll assemblies mounted within said cams and operated thereby, said assemblies spaced from one another about a length of tubing and comprising:

a. a plurality of arbors, and

b. supported on said arbors a plurality of die means which define axially spaced peripheral portions with grooves formed .therebetween.

2. Apparatus according to claim 1 wherein three forming roll assemblies are positioned spaced about l20 from each other, said forming roll assemblies being movable toward and away from each other relative to a tube finning station defined therebetween.

3. Apparatus according to claim 1 wherein said body member comprises a plurality of substantially cylindrical plates, located and secured in spaced apart relationship, said plates being interconnected by joining means.

4. Apparatus according to claim 3 wherein said joining means includes means positioning said body member within said housing.

Claims

1. Apparatus for forming axially spaced integral helical fins, said apparatus including a tube finning head assembly comprising: 1. a housing defining the outer surface of said head assembly; 2. a body member mounted within and interconnected to said housing, said body member being easily disconnected from said housing to be removed therefrom; 3. a plurality of cams journaled within an equal number of mating bores formed within the inner surface of said body member; 4. a plurality of forming roll assemblies mounted within said cams and operated thereby, said assemblies spaced from one another about a length of tubing and comprising: a. a plurality of arbors, and b. supported on said arbors a plurality of die means which define axially spaced peripheral portions with grooves formed therebetween.

2. Apparatus according to claim 1 wherein three forming roll assemblies are positioned spaced about 120* from each other, said forming roll assemblies being movable toward and away from each other relative to a tube finning station defined therebetween.

3. a plurality of cams journaled within an equal number of mating bores formed within the inner surface of said body member;

4. a plurality of forming roll assemblies mounted within said cams and operated thereby, said assemblies spaced from one another about a length of tubing and comprising: a. a plurality of arbors, and b. supported on said arbors a plurality of die means which define axially spaced peripheral portions with grooves formed therebetween.