US2506657A - Formation of tube ends - Google Patents

Description

May 9, 1950 H. N. WEBSTER 2,506,657

FORMATION OF TUBE ENDS Filed June 4, 1947 2 Sheets-Sheet 1 WITNESSES I N V EN TOR:

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FORMATION OF TUBE ENDS Filed June 4, 1947 2 Sheets-Sheet 2 Q as m 1 QL 56 I M I WITNESSES 1 N V EN TOR:

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Patented May 9, 1950 2.506.051 A FORMATION OF TUBE ENDS Henry N. Webster, Sebring, Fla., assignorlo Webster Corporation, Sebring, Fla., a corporation of Florida Application June 4, 1947, Serial No. 752,424

1 Claim. (Cl. 29-156) This invention relates to an improvement in the expansion, working and forming of thin walled tubes and more particularlyto the formml of an expanded end portion thereof.

It is old to expand metallic tube ends by means of a plunger forced within the end. It is also old to couple with the use of such plunger an outside die to coact with the inner operation of the plunger, forming the tube end between the die and plunger. I have found in practice that neither of these methods is effective in working with extruded aluminum tubing having a comparatively thin wall because both of these methods result in numerous failures by splittin or fracture. Of course, the same problem is present with any thin walled pipe manufactured by the extrusion proces in which the metal grain tends to run in an axial direction. There are disadvantages in attempting to obtain strength by thickening the wall of a tube which must be portable and therefore light as in the case ofv a portable section of a movable irrigation pipe line. A thicker tube wall means added weight, the expense of the additional metal and the added difllculty in forming thick walls of the pipe end to particular shapes to form a joint. This problem became particularly acute where it was necessary to first enlarge a thin walled aluminum pipe end and thereafter further work and. shape that enlarged portion of the pipe to form the female element of a pipe Joint.

The object of my invention, therefore, is to provide an effective means for expanding or working the. end of, a thin walled metallic tube manuf'actlired by the extrusion process. Another obj ect of my invention is the provision of means for expanding such tube ends without weakenin or reducing the wall thicknessthereof in the expanded portion. Another object of my invention is the provision of a means for expanding such tube end without subsequent splitting or fracturing. Another object of my invention is the provision of a. means for forming the ends of tubes of the type referred to above into the female elements of a pipe joint without weakening the area at the joint. Still further objects and advantages will become apparent fromthe following detailed description of a preferred form of my invention, reference being had to the' accompanying drawings.

Of these drawings, Fig. 1 is a conventional showin partially in .section of apparatus illustrating the performance of the first stage of the method of my invention.

Fig. 2 is the same as Fig. 1 except that it illusof the tube 6.

2 trates a later stage of the performance of the method of my invention.

Fig. 3 is the same as Figs. 1 and 2 except that it shows a still later stage of the performance of the method of m invention.

Fig. 4 shows a top plan view of apparatus providing a pair of roller dies which may be employed in a combined rolling and spinning operation as required in the final stage of the practice of the method of my invention.

Fig. 5 is a front elevation of-the apparatus of Fig. 4 with parts broken away and shown in section to better disclose important details of the structure and operation thereof.

Fig. 6 is a partial front view of the apparatus of Fig. 5 showing the roller dies at the completion of the combined rolling and spinning operation.

Fig. 7 is a partial end view of the apparatus looking from the right hand side of Fig. 6.

In describing the embodiment of this invention shown in the drawings, a specific terminology will be adopted for the purpose of clarity, but it is to be understood that it is not intended thereby to limit the invention to this detailed description of an illustrative embodiment thereof. Each term adopted is intended to include all equivalents thereof which operate in a substantially similar manner to accomplish a substantially similar resuit.

The practice of the method of my invention involves a plunger I mounted on a hydraulic power means comprehensively designatedas 2, a bracket 3 supporting said power means 2 and mounted on a base or frame member 4, 9. retaining ring 5 manually positioned at the end of the tube 6, a draw-down die 1 receiving an end of the tube 6 supported by a bracket 8 and the base or frame member 4 and a pair of roller dies l0 and II suitably supported and mounted as will be explained in detail later.

The plunger I is formed with a guiding or piloting section IS with an outside diameter equal to or very slightly less than the inside diameter The piloting section l5 should snugly fit inside the tube 6 without substantial expansion thereof and thus function in aligning the plunger l and the tube 5. The section 15 merges with an inclined section l5 which should be formed with a pronounced angle to the horizontal surface of section IS in order to provide a substantial thrust component to transmit an upsetting effect to the tube wall as the plunger l is forced into the tube 6. I have found than an angle of 30 gives' excellent results and provides the necessary thrust component in the direction of the axis of the tube 0. Of course this angle can be decreased provided the angle is sufllcient to effect a substantial thrust component to obtain the upsetting effect on the tube wall. For example, if this angle is so reduced that the plunger I operates primarily in performing a stretching and expanding function the benefits of my invention will not be obtained. The tube end will tend strongly to fracture or split because the force and effect of the die I is expended almost entirely in a radial direction. This is a mere stretching which clearly reduces the wall thickness of the tube 6. The same unsatisfactory resuits are obtained when it is attempted to expand the tube end by hydraulic pressure confined within the tube end and for the same reason. According to my invention the provision of a sharp enough angle to provide a force component exerting an axial thrust within the tube 3 results iri a substantial upsetting effect on the tube wall which increases rather than decreases the wall thickness. In fact I have observed in the practice of my invention an increase of wall thickness of between 2 to thousandths of an inch in thickness. On the other hand, if the angle of section II of the plunger I is too great, failures will develop because of buckling or gathering. It will thus be apparent to those skilled in the art that my invention involves the selection of an angle in section I5 which will provide a flow plane for the metal and at the same time exert a substantial axial thrust force on the tube 6. Section I6 merges into section I1 which receives the metal as it flows up and over section I6. Section I! is the diameter of the inside of the expanded portion and may be as much as 20% greater than the original inside diameter of the tube.

It is very important in view of numerous experiments to promote the longitudinal and easy flow of the metal in the wall of the tube 6 as section is of the plunger I enters the tube 6. It should be remembered in this connection that the grain structure of a tube formed by the extrusion process is inclined to run axially of the tube and my invention thus takes advantage of the existing grain condition. It has been found that the benefits of my invention are not obtained when an outer die of the usual type is provided. Apparently an outerconfining die interferes with the easy flow of metal up the flow plane of section I6 and onto section II of the plunger I. On the other hand, fractures, splitting and undesirable flaring develop when the plunger I is used without outside support at the terminal edge of the tube 6. Therefore, according to my invention, I provide an axially short circular retaining ring 5, recessed at 20 to receive the terminal edge of the tube 6 at its expanded diameter as in Fig. 3. This retaining ring 5 holds the end of the tube 6 without unduly restraining the free flow of the metal up and over the flow plane of section I6 and on to the section I! of the plunger I.

In operation, the retaining ring 5 is manually positioned around the terminal edge of the tube end as shown in Fig. 1 until the flaring edge, of

the. tube 6, developing from the action of the plunger I, is firmly seated in the recess 20 of the retaining ring 5 as in Fig. 2. Fig. 3 shows the retaining ring 5 at the conclusion of the expanding operation. When the plunger I is withdrawn, the ring 5 may easfly be removed by hand, being loosened,.if necessary, by a few taps from a hammer or similar instrument. It will be obvious that the length of the expanded portion of .details are well within the experience of the skilled artisan and have no direct bearing on the description of the method of my invention. The draw down die I is also of a conventional form well known to the art and need not therefore be described in further detail here except to point out the two steps in its functioning.

- This is effected by two spaced elements 22 and 23 which together make up the draw down die I. Element 22 reduces the diameter of the tube 6 and element 23 rounds in the end of the tube 8 as will be seen from Figs. 2 and 3. Clearly, the

length of the reduced section of the tube 3 depends upon the spacing of the elements 22 and 23 by the spacing rods 24. The pressure exerted by the power means 2 in forcing the plunger I into the tube 6 is also transmitted through the length of the tube to effect the functioning of the draw down die I contemporaneously with the formation of the expanded end of the tube 6.

Having now described the expanding stage of the method of my invention, I will next turn to the final forming stage which involves the use of a pair of roller dies consistingof inside roller I II and outside roller I I having cooperating ridges and grooves formed thereon. Inside roller I II is integrally mounted on a power driven shaft 25, the source of power being any conventional type and therefore omitted in the drawing as not pertinent to my invention. The outside roller II is mounted for free rotation on axle member 26 supported by a U-shaped member or yoke 21 with capacity for axial movement. It will be noted from Fig. 5 that the axle member 26 is considerably longer than the width of the roller II and the purpose of this is to allow sufficient free axial movement of the roller II to perform the spinning function as will be described later.

Tne yoke 21 is suspended by means of pivot connection 30 formed in the element 3| integrally mounted on a lever or operating arm 32 by means of nut 33 and lock washer 34 as shown in Fig. 5. It will be observed that a suitable vertical hole is formed in the arm 32 to receive the shank portion of element 3| therethrough. The arm 32 having a handle 39 is pivotally mounted on bracket 35 which is supported on the base or frame 36 in a conventional manner.

Itwill be noted in Figs. 4 and 5 that the tube 6 is positioned at an angle in both the vertical and horizontal plane. This angular positioning is done manually by an operator who holds the free end of the tube 6 during the operation. The purpose of this angularity is two fold: first, to positively hold the expanded end of the tube 6 onto the driven inside roller Ill; and second, to cause the floating outside roller I I to move to its proper operative position for starting the operation of combined rolling and spinning, which is at the extreme right on axle member 26 as shown in Fig. 5. This position is promoted by an oil tracking effect between the tube Ii and the outside roller I I resulting from the angularity referred to above. The pivotal connection 30 permits the outside roller to contact the tube 8 at the two high points of its two ridges regardless of the angularity of tube 6. The inside length of axle member 20 which determines the limits of the axial movement of the outside roller ll within the yoke 21 should be such that the outside roller II in its initial operative contact with tube 6 maintains its proper relation with the inside roller l0. The

points 40 on the tops of the ridges formed on the surface of outside roller l I must be definitely and at all times to the left of the points 41 on the tops of the similar ridges formed on the outside surface of the inside roller l0. -See Fig. 5. Because of this relationship between the rollers II and l I, downward pressure exerted on the outside roller ll will cause the roller II to gradually move axially to the left as grooves are rolled into the tube 8. The pressure exerted on the roller l I is controlled by an operator who exerts downward pressure on the handle 39. This develops a spinning operation through the urging of the metal to the left as well as downwardly. In this way there is an axial molding of the metal in the direction of the grain formation of the tube 6. The grain condition in the tube 8 naturally lends itself to a flow of metal longitudinally of the tube 8 and thus the forming operation works with the natural condition of this grain condition of the metal. At the conclusion of the combined spinning and rolling operation, the rollers I0 and l I appear as in Fig. 6.

While this invention has been described above in considerable detail and certain modifications thereof suggested, it will be apparent to those skilled in the art that various other changes and modifications may be made without departing of a thin walled metallic tube comprising first 6 enlarging the area to be given a corrugated formation to a diameter equal to that of the tops of the external ridges to be formed in said corrugated area, said enlargement being effected by the forcing into the end of the tube of a plunger having an outwardly inclined portion, the angle of said inclination being sufficient to provide an up-setting efiect whereby the wall is not made thinner from the expansive eifect, the end portion of said tube being peripherally supported externally during the operation of said plunger by an axially short retaining ring which exposes without external support a substantial part of the tube portion being enlarged, and thereafter rolling transverse corrugations in said enlarged area of said tube, to the depth of the original diameter of the tube; and, by means of the rolling, simultaneously molding the metal inwardly and longitudinally toward the enlarged end of the tube.

HENRY N. WEBSTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,206,395 Widell Nov. 28, 1916 1,647,447 Hartnett NOV. 1, 1937 2,027,018 Brinkman Jan. '1, 1936 2,072,359 Dobrick Mar. 2, 1937 2,157,252 Visser May 9, 1939 2,241,091 Hood May 6, 1941 2,243,932 Wery June 3, 1941 2,418,312 Michelman Apr. 1, 1947 FOREIGN PATENTS Number Country Date 754,801 France Aug. 28, 1933

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