WO1984000120A1

WO1984000120A1 - Tube expander

Info

Publication number: WO1984000120A1
Application number: PCT/AU1983/000083
Authority: WO
Inventors: Wlodzimierz Rast
Original assignee: Rast Patent Mfg Pty
Priority date: 1982-07-01
Filing date: 1983-06-27
Publication date: 1984-01-19
Also published as: EP0112853A4; EP0112853A1; JPS59501197A

Abstract

A tube expander of the type using an expansion die (11) comprised of segments (11A and 11B) for insertion into the end of a tube (20) to expand the diameter of the end of the tube (20) which is characterized by the insertion of the expansion die (11), which has a forward end (18), into the end of the tube (20) with the forward end (18) situated at the innermost part of the required expansion, expanding the forward end (18) of the expansion die (11) to produce a circular ridge (21) in the tube (20) and then pulling the expansion die (11) towards the end of the tube (20) to expand the tube (20) along a required length thereof, the reaction to the pulling procedure being taken by having the end of the tube (20) resting against a reaction face (7) on radially movable jaws (2) situated in a head (1), the head (1) being stationary in relation to the expansion die (11), the expansion die (11) being expanded and moved by a pull rod (8).

Description

"TUBE EXPANDER"

This invention relates to a tube expander and in particular it relates to a tube expander which can be used to expand a portion of a tube, preferably the end, to allow joining of the ends of two coaxially placed tubes and in particular it relates to an expander which can expand tubes of hard material such as hard drawn copper but which will be usable on soft copper tubing and other materials as well.

There are on record many forms of tube expander but the most general form are those in which a series of jaws are mounted to expand radially about an axis so that when they are inserted into a tube at its end the expansion of the jaws will stretch the material of the tube to increase its end diameter by the required amount, such as generally by the thickness of the wall of the tube to allow joining of two tubes by sliding the end of one tube into the expanded end of the other tube. Such devices are open to the objection that they cannot effectively work on tubes of hard material and inevitably tend simply to split the tube rather than expand it. See Australian Patent No. 426,882.

Another disadvantage referred to in the above Australian Patent is the area over which the jaws operate to expand the tube which requires a considerable force to be exerted on the handles of a tube expander of this form, and various attempts have been made to ease the force which must be applied, particularly those tube expanders which are for hand use. Among the methods of lowering the required force on the handles of these devices is one in which the arrangement is such that the jaws are moved in successive stages so that on the first operation of the handles a partial expansion of the tube only results and on further operation of the handles the tube is further expanded.

Attempts have been made to reduce this pressure by using an arrangement other than the normal cam operating on a drift, but as stated earlier, even if the required force can be exerted to expand the tube, the system of expanding jaws does not work with hard drawn tubing because the material splits rather than uniform expansion taking place around the perimeter of the tube. See International Application No. PCT/AU80/00038.

Because of the problems which exist with radially expanding jaws it has been proposed to expand a tube by driving in a former such as a ball for the required distance but this results in a problem in holding the tube against the relatively high force which is exerted to move the tube axially as the expansion takes place, and the types of grips which must be used to hold the tube against axial displacement in such a case tend to damage the wall of the tube if sufficient hold exists. Therefore this form of apparatus has not been successful because of the damage which occurs to the tubes adjacent to the area, or at the area, where expansion is taking place. The object of the present invention is to overcome the problems referred to above and to provide a tube expander which is relatively easy to operate so far as operating pressures are concerned and which will operate on harder material tubes without splitting and further will not damage the tube itself due to the need to hold it in grips against heavy axial forces applied during the expansion.

The objects are achieved according to this invention by expanding the tube over the area defined for the expansion by commencing expansion remote from the tube expander and causing expansion linearly towards the expander, the device preferably consisting of an expansion die in segmented form which can be moved into the end of a tube to the distance over which the tube is to be expanded and is then expanded outwardly to make contact with the tube and expand the tube by radial pressure at a circular area, the expansion die being then moved towards the tube expander to progressively expand the tube.

In this device the end of the tube which is being expanded is simply resting against the expander itself so that the tube need not be otherwise gripped, although guide means can be provided if required, whereby, because the tube is progressively expanded linearly towards the expander, the force required is considerably less than by some other methods and also splitting of the tube does not generally occur because of the relatively circular contact only at the area of the expansion die remote of the end of the tube. Because the pull is toward the expander the tube does not need to be firmly gripped as the expansion die pulls the tube firmly to the expander to provide the necessary reaction force.

The device can be constructed in various ways but according to a simple arrangement the expander can be of a similar form to the hand operated expanders used at the present time in which a head forms part of one handle and another handle is pivoted to the head to allow manipulation of a pull rod extending through the head, the head having jaws shaped to allow a tube of the required diameter to be engaged therein with faces against which the end of the tube rests, the pull rod having at its extremity a tapered portion and a flange and having, arranged to slide on the tapered portion, the expansion die which can be of segmented form by having longitudinally formed segments with the remote end of the expansion die given a fairly short radius and the die sloping back to a retaining ring for the sections of the die so that this expansion die can be pulled down onto the smaller part of the tapered portion on the pull rod as the pull rod is moved forwardly to position the expansion die at the locality where the inner end of the expansion is to occur, and by then moving the pull rod back the expansion die is forced outwardly as the sections of the die move on the taper to cause an annular outward expansion of the tube at this locality, but when full expansion has been reached continued pull on the pull rod causes the expansion die to move along the tube which has its end against the face on the jaws of the head until the expansion has been effected linearly to the end of the tube. The method of expanding a selected end part of a tube comprises:

(a) Inserting an expansion die into the tube to the further end of the area to be expanded remote from a head supporting the expansion die,

(b) engaging the end of the tube against a reaction face of the head,

(c) causing the expansion die to expand to the diameter of the required expansion, and (d) pulling the expanded die towards the reaction face to progressively continue the expansion to that end of the tube engaged on the reaction face.

The invention is characterised in that the expansion die is supported by a head and is arranged to be positioned in a tube through one end thereof to engage the inner surface of the tube at least remotely of the end of the tube, means being provided to expand the forward inserted end of the expansion die to effect an annular expansion of the tube at the forward end portion of the expansion die, means being also provided to pull the expansion die toward the head to progessively expand the end portion of the tube, means being provided on the head to engage the end of the tube being expanded to hold the tube against axial movement during the linear expansion action.

The tube expander according to the preferred form of this invention thus comprises a head having an aperture therethrough, a pull rod extending through the aperture, an expansion die positioned on a forward part of the pull rod, means to urge the expansion die forward on the pull rod, means to limit the forward movement of the expansion die on the pull rod, means on the pull rod to expand the expansion die when urged forward on the pull rod, means to pull back the pull rod in relation to the head, and a face on the head to engage the end of a tube to be expanded.

In order however that the nature of the invention will be fully appreciated an embodiment thereof will now be described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of the tube expander with the pull rod retracted.

FIG. 2 is a similar view with the pull rod moved forward as when commencing a tube expansion.

FIG. 3 Is a view of the tool as in FIG. 2 but to an enlarged scale, showing the tool sectioned on planes normal one to the other.

FIG. 4 is a plan of the expansion die, with part of the pull rod shown, the spring being section.

FIG. 5 is a longitudinal sectional view of the head and jaws and the expansion die mounted on the pull rod with a tube being pushed into position to be engaged by the jaws.

FIG. 6 is a view similar to FIG. 5 but showing the tube pushed forward and engaged in the jaws with its end against the face of the jaws and with the pull rod pushed forward into the tube to position the expansion die at the location where the expansion of the tube is to commence. FIG. 7 is again a similar view to FIGS. 5 and 6 but showing the pull rod actuated to expand the expansion die, with the flange positioned against the end of the expansion die in readiness to commence a traverse along the tube, and

FIG. 8 is a similar view but showing the expansion of the tube completed and showing the expansion die pulled back to the position where the tube is released from the expansion die and is releasable from the jaws.

Referring now particularly to the drawings, the head 1 has on it radially movable jaws 2 confined between a face 3 of the head 1 and a face 4 of a keeper 5 which is engaged on the head 1.

The jaws 2 have a recess '6 at their inner ends and a reaction face 7 against which the end of a tube to be expanded rests, this reacton face 7 being adapted to take the axial force generated on the tube during the operation of the expansion die and thus forming the means for holding the tube without having to use any form of gripping device engaging the outside of the tube remote from the end as has been the practice heretofore.

The pull rod 8 has at its end a tapered portion 9 and a flange 10.

The expansion die 11 consists of a first and a second series of longitudinally divided segments 11A and 11B grouped about the pull rod 8 and held together by a ring 12 engaging circumferential grooves In the segments 11A and 11B of the expansion die 11. The forward end of the expansion die 11 has an annular surface 14 which defines the expansion required at the end of the tube, a sloping surface 15 forming a lead to the annular surface 14, the surface of the expansion die 11 sloping inwards from the annular surface 14 to provide an expansion lead 16.

The inner surface 17 of the expansion die is shaped so that the expansion die 11 engages the tapered portion 9 of the pull rod 8 at the forward end 18 of the segments 11A and 11B of the expansion die, while the rear end 19 of the expansion die 11 rests on the pull rod 8 so that the segments 11A and 11B of the expansion die 11 can tilt to cause the forward ends 18 of the segments 11A and 11B to expand outwardly under action of the tapered portion 9, while retaining the rear end 19 in contact with the pull rod 8.

The surface 14, together with the expansion lead 16, serve to expand the tube 20 when the pull rod 8 is moved rearwardly from the position shown in FIG. 6 to that shown in FIG. 7, at which stage the tube has an annular expansion 21 remote from its end.

At the rear end of the expansion die 11 is a spring 23 confined between the rear end of the expansion die 11 and a collar 24 which, in the illustrations, is shown as welded to the pull rod 8 but can be adjustable along the pull rod 8 by threading the pull rod and the collar 24 or by provided grub screws or the like to lock the collar 24 in position on the pull rod 8 at the position where the required force of the spring 23 is achieved to urge the expansion die 11 forward. The reason for using segments 11A and 11B of different form is to ensure that the expansion die 11 will form a true circular surface which will expand the tube without draw marks caused through gaps between the segments . The segments 11A are the main segments of the device but intermediate segments 11B fit between the main segments 11A and are tapered and angled such that the segments 11A and 11B can have a certain amount of longitudinal movement between them to complete a circle at the annular surface 14 and moreover to have the edges of the segments 11A and 11B at an angle to the line of the draw to ensure that the expansion of a tube takes place in true circular form without forming fins on the inside of the expanded portion. The angular interengagement is on the lines 11C, that is at the annular surfaces 14.

To allow accommodation of the one group of segments 11A in relation to the other group of segments 11B the circumferential grooves in which the retaining ring 12 is accommodated are longer in the segments 11A than in the segments 11B so that when the device is pushed into a tube preparatory to expanding the end of the tube the segments can all accommodate themselves correctly in relation to the inner face of the tube, but when the initial expansion takes place which occurs because of the friction between the annular surface 14 of the segments and the inside of the tube 20 to be expanded all segments 11A and 11B will be pushed outward in the position they have assumed. When however the flange 10 on the end of the pull rod 8 contacts the end 18 of the segments 11A and the segments 11B and all segments are then moved together under control of the flange 10 which holds the expansion uniform during the draw of the expansion die 11 rearwardly in the tube to the end of the completed expansion. The grooves are designated 25.

Referring to the operation of the device, It will be seen from FIG. 6 that the pull rod 8 with its tapered portion 9 and flange 10 is encircled at its forward portion by the segments 11A and 11B of the expansion die 11 and these segments 11A are free to move at the forward end 18 of the expansion die 11 under control of the tapered portion 9 of the pull rod 8, and when It is required to expand a tube 20, the tube is pushed in the direction of the head 1 as shown in FIG. 5 and because of the sloping surface 15 on the segments 11A and 11B of the expansion die 11 will cause the segments 11A and 11B of the expansion die 11 to move inward generally radially at their forward end provided the pull rod 8 is projected forwardly a sufficient distance to bring the end 18 of the segments 11A and 11B of the expansion die 11 into the position shown in FIG. 6.

At this stage the annular surface 14 engages the inner face of the tube 20 and slides along the tube 20 as the pull rod 8 is advanced, the spring 23 being compressed at this stage to ensure that contact of the inside of the tube 20 by the annular surface 14 is retained as the pull rod 8 is advanced to the position shown in FIG. 6.

FIG. 6 shows how the end of the tube 20 is engaged in the jaws 2 which are urged Inwards by a spring circlip 26 to have the shoulders 27 of the recess 6 on the jaws 2 engage the tube 20 and to have the end of the tube 20 engage the reaction face 7 on the jaws 2 to take the thrust.

If the pull rod 8 is now pulled back in the direction of the arrow in FIG. 6, the forward ends 18 of the segments 11A and 11B of the expansion die 11 will be forced outwards as shown in FIG. 7, the flange 10 limiting the outward movement of these ends 18 of the segments 11A and 11B of the expansion die 11 to the amount of expansion required on the tube 20.

During the movement of the pull rod 8 from the position shown in FIG. 6 to the position shown in FIG. 7 the expansion die 11 does not move axially but the forward end of the expansion die segments 11A and 11B move out to expand the effective diameter of the end of the expansion die 11 forming the annular expansion 21 to give a circumferential ridge. When pull continues the expansion die 11 is moved forward with the pull rod 8 to the position shown in FIG. 8, this movement forming the expanded portion 30 required on the tube 20.

As this end of the tube 20 is expanded the jaws 2 move outward against pressure of the spring circlip 26 to still accommodate the expanded end of the tube. At this stage the tube 20 can be removed as the expanding action is complete.

The movement between the head 1 and the pull rod 8 can be obtained by any suitable actuating members such as a pair of levers 32 and 33 , the lever 32 being connected to the body 29 which supports the head and the other lever 33 pivoted to the body 29 and having a connection (not shown) to the pull rod 8. In place of levers it Is possible to use a hydraulic mechanism which can readily be applied between the pull rod and the head.

The form of the expansion die can of course be varied and instead of it being formed of separate segments it can take the form of an expanding ring with a rounded outer perimeter, that is rounded in cross-section, the purpose of the expansion die being to move outwardly and form an outwardly pressed circular ridge and to then move the expansion die axially in the tube while the end of the tube is held against the reaction face of the head to progressively linearly expand the tube.

Not only does this allow the tube to be expanded with a lesser force but it avoids the splitting of the tube because the expansion takes place only at a small circular area and moves forward linearly, again operating only on a small area at any time.

The device can be made with interchangeable heads to take different sizes of tube or the taper on the pull rod can be provided with adjusting means which allow the expansion die to have limited movement only on the taper of the rod such as by moving an end rim or collar axially along the pull rod or alternatively the expansion die itself can be attached to means which limit its outward movement on the taper to thereby determine its starting diameter and such adjustment can be indexed to allow the tool to be used on tubes of different size by appropriately positioning the control means for the position of the expansion die on the taper.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. The method of expanding a selected end part of a tube which comprises:

(a) Inserting an expansion die into a tube to the further end of the area to be expanded remote from a head supporting the said expansion die,

(b) engaging the end of the tube against a reaction face on the said head,

(c) causing the said expansion die to expand to the diameter of the required expansion, and

(d) pulling the expansion die towards the said reaction face to progressively continue the expansion to that end of the tube engaged on the said reaction face.

2. The method of claim 1 further characterised by the steps of engaging the end of the tube to be expanded in radially movable jaws on the said head, and urging the said jaws inward to engage the periphery of the end of the said tube, said reaction face being formed on said jaws to engage the said end of the said tube.

3. The method of claim 1 or 2 further characterised by the steps of urging a series of segments forming the said expansion die axially on a tapered pull rod to expand the said expansion die, but causing the said segments to move back against the urging means when inserting the said expansion die into the said tube whereby to cause the said segments to move forwardly in contact with the internal face of the said tube when inserting the said expansion die In the said tube.

4. A tube expander comprising a body having a head supporting an expansion die and having means to actuate the expansion die to expand a portion of said tube when placed over the said die characterised in that the said expansion die is supported by the said head and is arranged to be positioned in a tube through one end thereof to engage the inner surface of the said tube remotely of the said end of the tube and has an expansion lead, means to expand the forward Inserted end of the said expansion die to effect an annular expansion of the tube at the forward end portion of said expansion die, means to pull the said expansion die towards the said head to progressively expand the said tube by means of the said expansion lead, and means on the said head to engage the end of the tube being expanded to hold the said tube against axial movement during the linear expansion action.

5. A tube expander according to claim 4 characterised in that the said expansion die comprises a series of segments held together at a rear end but expandable at a forward end.

6. A tube expander according to claim 5 characterised in that the said expansion die comprises two series of segments having at the forward ends interengaging sloping surfaces at an annular surface which engages the said tube to expand same, one said series of segments being longitudinally movable one to the other to maintain a relatively continuous annular surface.

7. A tube expander according to claim 4 characterised in that the said means to engage the end of the tube to hold the tube against draw reaction comprises a reaction surface on radially movable jaws carried on the said head .

8. A tube expander comprising a die arranged to expand an end portion of a tube by movement of the die relative to the tube and including means to actuate the die to cause the expansion of the tube, characterised by

(a) an expansion die adapted to be inserted into the tube through an end of the tube to be expanded,

(b) a body and head supporting the said expansion die to project from the said head Into the said tube,

(c) a reaction face on the said head to engage the end of the tube to be expanded when the said expansion die is advanced to project into the said tube ,

(d) means to exert an expansion force on the said die to expand the end of the die in the said tube remote from the said reaction face,

(e) means to limit expansion of the expansion die when the said expansion force is exerted, and

(f) means to pull the expansion die toward the said head and through the end of the tube which engages the said reaction face, whereby the said die first expands the said tube at the further part of the said expansion and then progressively expands the die by axial movement to the end of the tube.

9. A tube expander according to claim 8 wherein the expansion die comprises segments having an annular surface at the forward expansion end to engage the inside surface of the tube and has a forward inward sloping surface and a rearward inward expansion lead extending from the said annular surface.

10. A tube expander comprising a body having a head supporting an expansion die and having means to actuate the expansion die to expand a portion of the said tube when placed over the said die characterised by a pull rod extending through an aperture in the said head, an expansion die positioned over a forward portion of the said pull rod, means to urge the expansion die forward on the said pull rod, means to limit the forward movement of the expansion die on the said pull rod, means on the said pull rod to expand the said expansion die when urged forward on the said pull rod, means to pull back the said pull rod In relation to the said expansion die, and a reaction face on the said head to engage the end of said tube to be expanded.

11. A tube expander according to claim 10 characterised by jaws arranged about the said pull rod and supported by the said head to be radially movable thereon, means to urge the said jaws inwards, a recess on each said jaw adapted to engage the end of a said tube to be expanded, the said reaction face being positioned on the said jaws within the said recess.

12. A tube expander according to claim 10 or 11 characterised by a series of segments forming the said expansion die and arranged about the said pull rod, and by a tapered portion on the forward end portion of the said pull rod expanding to the said forward end of the said pull rod, and by a flange at the forward end of the said pull rod, said segments of the said expansion die engaging the said tapered portion at a forward end portion and the said pull rod at a rear end portion.

13. A tube expander according to claim 10 or 11 characterised by a first series of segments forming the said expansion die and arranged about the said pull rod, and a second series of segments disposed between the said first series of segments, a retaining ring engaging a groove at a rear end portion in each said segment, said grooves in one said series of segments being wider to allow limited longitudinal movement of one said series of segments in relation to the other said series of segments, each said segment having part of an annular surface on its end portion remote from the said retaining ring positioned to be pressed against the inner surface of the tube to be expanded, the said series of segments being angled in relation to the direction of movement of the said expansion die where they contact at the said annular surface.

14. A tube expander according to claim 10 or 11 characterised in that the said means to expand the said expansion die comprise a pull rod having a forward end projectable through the said aperture in the said head and tapered at its forward end portion to an increased diameter and having a flange at the said forward end, the said expansion die comprising a first series of segments arranged about the said pull rod, and a second series of segments between the said first pair of segments, a retaining ring encircling the said segments at a rear end portion and engaging a groove in each said segment to longitudinally confine the said segments, said rear end portion of each segment engaging the said pull rod, a forward portion of each said segment engaging the said tapered portion of said pull rod, and angled interengaging faces on the said first and second series of segments at an annular surface positioned to engage the inside of a tube when the said expansion die is inserted in a tube.

15 . A method of expanding tubes substantially as described and illustrated.

16. Means for expanding the ends of tubes constructed and operating substantially as described and illustrated.