US2319216A - Tube expander - Google Patents

Description

E. A. DEWALD TUBE EXPANDER May 18, 1943 Filed June 18, 1940 INVENTOR ATTORNEYS) C Q Q Q Q Q Q Patented May 18, 1943 UNITED STATES PATENT OFFICE.

I TUBE EXPANDED 'Edward A. Dewald, Massillon, Ohio, assignor, by

usignmc meme l Jersey ntl, to The Babcock & Wilcox Newark, N. 3., a corporation of New Application June 18, 1940, semi No. 341,080

. with a preferred embodiment thereof, illustrated This invention relates to pull-type tube expanders of the sort chiefly used to expand boiler and heat exchanger tubes into drums and tube sheets, and, in particular, to improved actuating means for such expanders.

The object of this invention generally is to provide a tube expanding tool in which simplicity of structure and operation is combined with easy adaptability to different jobs. A particular ob-.

iect of my'invention is to provide a complete apparatus having these qualities suited to carry out the method of tube expanding described and claimed in the co-pending application of Maxto higher temperatures and pressures. The resulting demand for heavier walls and smaller diameters in the tubes and greater thickness in the tube sheets presented a tube expanding prob- "lem' which the conventional tools and methods of the prior art were unable to solve.

I am aware that a number of diflerent actuating mechanisms for such expanders have been recently disclosed, particularly in my co-pending applications Serial Nos. 298,345 and 301,092, flled Oct. 25, 1939, now Patent No. 2,275,614, and the above mentioned application of Maxwell. The

subject matter of the present invention is an improvement over these previously known actuating devices for pull-type expanders particularly in providing a simpler and more fool-proof device of outstanding flexibility of application both in the factory and in the fleld.

In general, I provide a hydraulically operated expander in which the expanding operation and the resetting of the expander is controlled by a. simple two-position valve, the necessary differential movement beween the taper pin and the expander head being automatically obtained. The means for accomplishing this automatic positioning of the parts of the expander proper are wholly outside ofthe hydraulic portion of the device, making for simplicity. The means provided for adjusting the device for diilerent jobs are likewise wholly outside of its hydraulic portions, making for freedomfrom leaks.

The invention will be'desc'rlbed in connection tion in a heat exchanger tube just prior to the commencement of .the expanding operation;

. Fig. 2 is an enlarged view of a portion of Fig. 1 showing the mechanism of my invention which prevents the rearward movement of the expander head before it has been fully expanded in its original position; and

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 2.

In the following detailed descriptions of the structure and operation of my invention the terms "inner and outer" shall be taken to mean in a direction into and out of, respectively, the tube to be expanded into the tube sheet when the expander is in working position.

Taking up structure first and referring to the drawing, my complete device includes a supply pipe I and return pipe 2 by which fluid under pressure to operate the expander is brought to and from the hydraulic portions thereof. l and 2 are connected to the inlets I and 34 of the cylinder 9 by means of the pipes i and 6 through the valve 3. This valve is actuated by the handle 4 which has only two working positions and is the only control used in the operation of my invention. In one position valve 3 connects pipe I to pipe 5 and pipe I to pipe 6;. in the other, pipe I to pipe 8 and pipe 2 to pipe 5.

The hydraulic mechanism of the device comprises a cylinder 9 having an outer head 3 through which the fluid port I communicates with the outer face ll of the piston II and an inner head 32 through which the fluidport 34 communicates with the inner face I3 of the piston ID. The piston rod I 5 passes through the inner cylinder head 32, leakage around it being prevented by a pressure seal comprising the U- shapedleather ring 36 held in place by the T- shaped metal ring 38 which is secured in a suitable annular recess in the head 32 by the screws 31. A number of holes 33 through the metal ring 33 provide a passage from the channeled face of the U-ring 36 to the inside of the cylinder 9. By means of this passage hydraulic pressure in the cylinder 9 is communicated'to the channel of the U-ring 38, thus providing a pressure-seal around the piston rod l5. This piston rod is threaded at its outer end into the double acting piston III, the inner and outer faces II and I3 of which are sealed'by the cup leathers I2 and u.

v The inner head 32 carries the horn 35 remov- Pipes.

ably afiixed to it by the set screw -33. This horn 33 surrounds the piston rod II which carries the connector sleeve I! on its outer end. The horn 35 serves as a bearing for the sleeve l1 and is of suillcient length to permit that sleeve to have a free travel equal to the stroke of the piston 13 between the inner cylinder head 32 and the steel balls 29 set in the inner end Portion of the horn itself.

The structure at the inner end of the horn 35 is of great importance in my invention and is shown enlarged in Figs. 2 and 3; The sleeve ll, threaded onto the piston rod l5, as shown at It, connects the taper pinv IQ of the expander proper to the piston Ill. The inner end of the sleeve I1 is recessed as shown at 40 to permit it to clear the steel balls 29. These balls are inserted in the holes 4|, here shown four in number. which are drilled radially in the walls of the horn 35 equidistant from its inner end. The diameter of the holes 4| is reduced at the bottoms thereof so as to prevent the balls 29 from passing through them but is kept sufficiently great to permit a substantial part of the balls 29 to protrude past the inside surface of the horn 33. The balls 29 are resiliently held in the bottoms of the holes 4| by the fingers 28 of the slit cylinder spring 21 fixed around the outside of the horn 35.

The outer end of the expander tube 24. carries the guide collar 23 threaded around it. This guide collar 23 is of slightly less outside diameter than the inside diameter of the horn 3.3,which serves as a bearing for it. At the extreme inner end of the horn 35 the horn cup 30 is removably afllxed by the set screw 3|. The set screw 3| bears against the collar 42 on the outer end of horn cu 33, this collar having an outside diameter proper to secure a snug fit inside the horn 35 and an inside diameter sufficient amply to the collar 42 serves as a stop limiting the inward travel of the expander tube 24 by abutment against the piston guide 23.

The expander proper in the embodiment il1ustrated, consists of the expander tube 24 carrying at its inner end the longitudinally split expander head 25 and the taper pin l9 carrying on the threaded portion 22 at its inner end the adjustable stop 2|. While I have illustrated my invention by a device employing this specific expander, it is to be understood that other pull-type ex-l panders may be used, for example, with a diagonally slit expander head or with a single or double split-ring expander head.

Taking up the operation of my invention, when the device has been placed in the position shown in Fig. 1, with the expander head inside the heat exchanger tube 23 which is to be expanded into the tube sheet. the handle 40f the valve 3 is turned to connect pipe I to pipe 3 and pipe 3 to pipe 2, admitting fluid under pressure to the inner face i3 of the piston Ill and permitting fluid in cylinder 3 outside the outer face ll of the piston ll tobe discharged.

The pressure of this fluid on the forward face a I 3 of the piston In forces this piston rearward in the cylinder 3. The piston 10 draws with it, by means of the piston rod l3 threaded into it, the taper pin 13. The rearward motion of the pin l3, by wedge action of its tapered portion 20, operates to expand the slotted head 23' of the expander tube 24. This expansion continues until the adjustable stop 2| on the end of the .clear the expander tube 24. The outerend of v taper pin it comes into contact with the forward face of the head 23. The expander tube 24 is prevented from moving rearward-during the expanding of its split head 23 by the resistance of the four steel ball 29 to the rearward motion of the piston guide 23 into which the expander tube 24 is threaded. These balls thus act upon the expander tube as stops or retarders. The pressure of the fingers 23 of the slit cylinder spring 21 is such that the resistance which the balls 29 offer to the rearward motion of. the piston guide 23 is greater than the rearward force exerted on the expander tube 24 by the wedging action of the tapered portion 23 of the withdrawing pin l3, but by no means as great as the force exerted by .the piston 13.

Thus, the tube 23 is expanded into the tube sheet at the point to which the expander head 25 reaches when the horn cup 33 is in position against the outer end of the tube 23. After the expander head 25 of the expander tube 24 has been fully expanded as described, the withdrawing of the taper pin l9 continues by reason of continued rearward motion of the piston i3 and the guide piston 23 forces open the steel balls 29. The now fully expanded head 23 passes rearward through the boiler tube 23 seating it securely the entire depth of the tube sheet. The

whole tool is then withdrawn from the tube 23.

To reset the tool for exp nding mother tube of the same diameter into a tube sheet of the same thickness it is merely necessary to turn the handle 4 of the valve 3 to the position connecting supply pipe I to pipe 3 and discharge pipe 2 to pipe 3. Fluid pressure then forces piston l3 forward and discharges the fluid in cylinder 9 the inner face l3 of the piston. The motion of piston ll carrie piston. rod is and taper pin l8 forward moving the expander tube 24 by contact between the inner face of the connector sleeve I1 and the outer face of the guide collar 23 until the moving parts of the tool are again in the position shown in Fig; 1. The forward motion of the piston l0 pushes t e piston guide 23 past the balls 29 which drop into the recess 43 at the inner end of the connector I'I without any attention from the operator. Thus the entire cycle of operation is completed and the proper differential motion of the parts of the expander proper automatically secured by a simple two-position control.

When it is desired to adapt the tool for use with boiler tube of different diameter. it is only necessary to remove horn 33 by means of set screw 33 which holds it to the inner head 32 of cylinder 3, substitute a different expander proper, taper pin II and expander tube 24, and adifl'erent horn cup 33, all adapted to the new diameter, and reassemble the device. I

The substitution of one expander mechanism for another is readily made by changing the connector I! for one adapted, at its inner end to receive the outer threaded portion ll of the new taper pin and by changing the piston guide 23 for one adapted to receive the threads of the new expander tube. The outside diameter of the piston guide 23 and connector l'l remain the same A particular advantage of my invention is that it provides a complete flexibility of range for the device without requiring any adjustment of, or interference with, the hydraulic portions of the actuating mechanism. Thus, when the cup leathers i2 and H of the piston l and the piston rod sealing leather 36 in the inner head 32 of the cylinder 9 are properly and satisfactorily fitted to give fluid tight joints, they are never disturbed by adjustments made to adapt the device from Job to job.

Moreover, the structure of the hydraulic portion of the device is extremely simple. The complexity which might beintroduced by the necessity of delaying the withdrawal of the expander tube 24 until the wedge 20 has fully expanded its head is entirely obviated by the employment of the steel balls 29 and spring 21. This feature of my invention provides a fully automatic means of securing the requiredrelative position of expander tube 24 and taper pin 19 at all steps of the operation of the tool, both in expanding and in resetting.

It is to be understood that my invention is not limited to the details of construction illustrated and described, but includes all embodiments falling within the scope of the appended claims. In these claims, the meaning to be given to inner and outer and related terms is the same as that already defined and used in the foregoing specification.

I claim:

1. In apparatus for expanding and drawing a portion of a tube disposed in a tube seat formed in a wall of a pressure device, a mandrel having a tapered portion, an expansible tube drawing head mounted for relative longitudinal movement on the mandrel, a stop on the mandrel adjacent the larger end of said tapered portion, means for pulling the mandrel out of the tube after it has been so moved as to position the retracted head within the tube and at a position well beyond the outer end of the tube seat, and an automatically releasable retarder including spring pressed elements normally positioned in the path of movement of a retarder engaging element moving with the head and preventing said head from moving with the mandrel while said stop is approaching the head, the release of said retarder being produced when the longitudinal force of the moving mandrel against the expander head overcomes the head retarding forces of the spring pressed elements of the retarder.

2. In apparatus for expanding and drawing a portion of a tube disposed in a tube seat formed in a wall of a pressure device, a mandrel having a tapered portion, an expansible tube drawing head mounted for relative longitudinal movement on the mandrel, a stop on the mandrel adjacent the larger end of said tapered portion, means for pulling the mandrel out of the tube after it has been so moved as to position the retracted head within the tube and at a position well beyond the outer end of the tube seat, and an automatically releasable retarder including spring pressed elements normally positioned in the path of movement of the head or a retarder engaging element moving therewith and preventing said head from moving with the mandrel while said stop is approaching the head, said spring pressed elements being structurally and functionally separate from said pulling means, the release of said retarder being produced when the longitudinal force of the moving mandrel against the expander head overcomes the head retarding forces of the spring pressed elements of the retarder.

3. In apparatus for expanding and drawing a part of a tube disposed in a tube seat formed in a wall of a pressure device, a mandrel having a portion tapered downwardly toward the adjacent end of the tube, an expansible tube drawing head mounted for relative longitudinal movement on the mandrel, a stop on the mandrel adjacent the larger end of said tapered portion, an operator pulling the mandrel out of the tube after the mandrel has been moved so as to position the retracted head within the tube and at a position well beyond the outer end of the tube seat, a retarder separate from the operator and including an element normally positioned in the path of movement of the head or a retarder engaging element moving therewith to prevent the head from moving with the mandrel until the head is efi'ectively expanded, and means releasably mounting the retarder so that its release is effected when the longitudinal force of the mandrel against the expander head reaches a predetermined value.

EDWARD A. DEWALD.

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