GB2066122A

GB2066122A - Sizing a tube end

Info

Publication number: GB2066122A
Application number: GB7943817A
Authority: GB
Original assignee: Vickers Ltd
Current assignee: Vickers Ltd
Priority date: 1979-12-20
Filing date: 1979-12-20
Publication date: 1981-07-08
Also published as: GB2066122B

Abstract

The invention provides an apparatus for sizing the end 9 of a tube. The apparatus comprises two sizing members 7,8 positioned one inside the other so as to provide a ring-like gap between the members. One of the members is an axially split mandrel, while the other is in the form of a die. The end of the tube which is to be sized is positioned within the ring-like gap between the two members, and a wedging member is moved against the axially split mandrel so as to deform the tube end against the die member. The axially split mandrel is preferably the inner 7 of the two sizing members, the outer 8 of the two members being the die. The invention also provides a method of sizing the end of a tube, in which the tube is subjected to a series of sizing treatments in an apparatus of the invention, each successive treatment involving different pairs of sizing members so that at the end of the treatment the tube end is deformed plastically, and not elastically. <IMAGE>

Description

SPECIFICATION Sizing a tube end This invention relates to apparatus for sizing an end of a tube (or the like).

When butt welding tubes together end-to-end, the welding is greatly improved and easier to perform if the mating tube ends (usually circularly cylindrical) have identical outside dimensions and are as accurately shaped (e.g. perfectly round and not oval) as possible.

According to the invention there is provided apparatus for sizing an end of a tube (or the like), comprising two sizing members positioned one inside the other so as to provide a ring-like gap between the members into which the tube end may be inserted around the inner sizing member, one of the sizing members being an axially split mandrel consisting of a cylindrical array of individual sizing segments separated from one another by small gaps between adjacent segments and the other sizing member being constructed as a die, the apparatus further comprising a wedging member which is axially movable relative to and coacts against the axially split mandrel so as to exert a wedging action thereon to bring about a reduction in the width of the ring-like gap and thereby deform the tube end against the die member, and power means operable to effect such axial movement of the wedging member.

Suitably the inner sizing member is the axially split member, the wedging member then consisting of a tapering rod.

Preferably, the two sizing members are removable to enable replacement by different sizing members suitable for sizing a differently dimensioned tube end.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which: Figure 1 is a vertical sectional view through one form of sizing apparatus in accordance with the invention; and Figure 2 is an end view of the apparatus, with sizing die omitted, showing an axially-split sizing mandrel.

Referring to Figures 1 and 2, the sizing apparatus comprises a cylindrical body 1 which is open at its left-hand end in Figure 1 to allow insertion of the various components of the apparatus into the body 1. Towards the other end, a double-acting hydraulic cylinder chamber 2, provided with appropriate inlet and outlet ports, is defined within the cylindrical body, and a piston assembly, consisting of a central rod section 3, a piston 4 within the chamber 2, and a tapering rod 5, is axially slideably supported by a liner 6 mounted within the central regim of the cylindrical body.

Positioned within the open end of the cylindrical body are inner and outer sizing members 7, 8, the inner sizing member being fitted around tapering rod 5 and being radially spaced away from the outer sizing member so as to provide an annular gap between the sizing members, into which the end 9 to be sized of a tube is inserted. The outer sizing member 8 is constructed as a die and is secured within the cylindrical body 1 by means of several shear buttons, one of which is shown at 10, which are a push-in fit. The liner 6 is likewise secured by means of push-in shear buttons such as 11. The inner sizing member is an axially split mandrel consisting of a cylindrical array of individual sizing segments 12 (See Figure 2).Each segment is free to move radially towards and away from the die 8 but its angular position is maintained fixed by an associated key 13, secured within the body 1, which projects into a keyway 14formed in the sizing segment 12. The segments 12 have tapering inner surfaces to conform with the taper provided for the outer surface of the rod 5 and are formed with a shoulder 25 which engages behind the die 8 so as to prevent the segments 12 from becoming separated from the body 1.

In use, with the piston assembly displaced to the right in Figure 1, the tube end 9 is introduced into the annular gap between the sizing members 7, 8 and then hydraulic pressure is introduced into the righthand end of the chamber 2 to displace the piston assembly to the left. As the tapered rod 5 moves axially relative to the sizing segments 12, it exerts a wedging action on these segments due to the interaction between the contacting surfaces, thereby forcibly urging the sizing segments radially towards the die 8. In this way, the tube end is plasticaliy deformed into intimate contact with the inner such face of the die, to provide the required circular shape and dimensioning.Suitably, the taper angle of the interacting surfaces of the rod 5 and sizing segments 12 is about 3 -4 to the axis of the apparatus.

To replace the die 8 and liner sizing member 7 with the same components but having a different size, so as to adapt the apparatus for sizing larger or smaller tube ends, suitable means are provided for the easy release of the tapering rod 5 and die 8. As shown in Figure 1, the tapering rod 5 is a hollow rod fitted around a central rod 15 and secured there by a locking nut 16 and washer engaged on a screwthread formed on the end of the central rod 5, so that the tapering rod can be released by merely removing the locking nut 16. The die 8 is released by removing the shear button 10. If required, the apparatus can be dismantled for servicing purposes by also removing the shear button 11 and withdrawing the liner 6.

Although the disclosed arrangement is preferred, it would be possible in a modification for the die to be a central part surrounded by the sizing segments which would be moved radially inwardly due to the wedging action of an axially moveable cylindrical wedging element surrounding the sizing segments.

To remove any possibility that the tube end deformation may be partly elastic, which could result in a partial return to its undeformed shape after removing the tube from the sizing apparatus, the tube end can be progressively formed above the elastic limit using a succession of different pairs of sizing members.

Claims

1. An apparatus for sizing an end of a tube (or the like), comprising two sizing members positioned one inside the other so as to provide a ring-like gap between the members into which the tube end may be inserted around the inner sizing member, one of the sizing members being an axially split mandrel consisting of a cylindrical array of individual sizing segments separated from one another by small gaps between adjacent segments, and the other sizing member being constructed as a die, the apparatus further comprising a wedging memberwhich is axially movable relative to, and coacts against, the axially split mandrel so as to exert a wedging action thereon to bring about a reduction in the width of the ring-like gap and thereby deform the tube end against the die member, and power means operable to effect such axial movement of the wedging member.

2. An apparatus as claimed in claim 1, wherein the axially split mandrel is the inner sizing member.

3. An apparatus as claimed in claim 2, wherein the wedging member is a tapering rod.

4. An apparatus as claimed in claim 1, 2 or 3, wherein the sizing members are removable from the apparatus to enable replacement by different sizing members suitable for sizing differently dimensioned tube ends.

5. An apparatus as claimed in any preceding claim, wherein the said power means comprises a double-acting hydraulic cylinder which is arranged to act upon the wedging member through a piston assembly.

6. An apparatus as claimed in any preceding claim, wherein each segment of the axially split mandrel is maintained in a fixed angular position by means of a key secured within the body of the apparatus which key projects into a keywayformed in the respective segment of the axially split mandrel.

7. An apparatus as claimed in any preceding claim, wherein the axially split mandrel has a taper angle of 3 to 4 degrees.

8. An apparatus for sizing an end of a tube, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

9. An apparatus as claimed in claim 8, wherein the axially split sizing member is the inner one of the two sizing members.

9. A method of sizing an end of a tube, which comprises repeatedly subjecting the end of the tube to a sizing treatment in an apparatus as claimed in any preceding claim, each successive sizing treat ment using a succession of different pairs of sizing members so as to ensure that the tube end is deformed plastically, and not partly elastically.

New claims or amendments to claims filed on 3 April 1981 New or amended claims:

8. An apparatus for sizing an end of a tube (or the like) comprising a pressure-resistant body within which there are two sizing members positioned one inside the other so as to provide a ring-like gap between the members into which the tube end may be inserted around the inner sizing member, one of the sizing members being split axially and consisting of a cylfndncal array of individual sizing segments separated from one another by small gaps between adjacent segments and the other sizing member being constructed as a die, the apparatus further comprising a wedging member which is axially movable relative to and which coacts against the axially split member so as to exert a wedging action thereon to bring about a reduction in the width of the ring-like gap and thereby to deform the tube end against the die member, and power means operable to effect such axial movement of the wedging member.