AU2005201610A1

AU2005201610A1 - Method and device for engaging a bore

Info

Publication number: AU2005201610A1
Application number: AU2005201610A
Authority: AU
Inventors: Jonathon William Langford; Nicholas John Langford
Original assignee: ALTRUM Pty Ltd
Current assignee: ALTRUM Pty Ltd
Priority date: 2004-04-23
Filing date: 2005-04-18
Publication date: 2005-11-10
Anticipated expiration: 2025-04-18
Also published as: AU2005201610B2

Description

in o oo

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): ALTRUM PTY LTD Invention Title: METHOD AND DEVICE FOR ENGAGING A BORE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 SField of the Invention CThe present invention relates to a method and device for engaging a bore. The present invention also relates to a method and device for forming an anchor in a hard material 00 such as masonry, rock and concrete.

Background of the Invention

NO

In a shell and tube or multi-tube heat exchanger, a bundle of c tubes is used to provide a high surface area for heat exchange. The bundle of tubes is mounted within the shell Ci and supported in an array using a tube sheet. Each tube sheet is provided with a plurality of smooth bore holes arranged to receive the tubes and hold each tube at a fixed distance relative to the other tubes in the bundle.

It is common practice for the holes in the tube sheet to have a diameter that is greater than an outer diameter of the tubes to make it easy to load the tubes into the tube sheet.

To secure the tubes in place once inserted into the holes of the tube sheet, each end of the tube is expanded to match the diameter of the holes so as to create a fluid seal. The tubes may equally be held in position in the tube sheet by welding or brazing after expansion.

From time to time, the tubes in a heat exchanger or boiler need to be replaced due to fouling, corrosion or other forms of damage and prior art methods of removing one or more tubes from the tube bundle exist. One such method is to use a shaft provided with an integral tapered threaded tip known in the art as a "spear". The tapered tip of the spear is screwed into the bore of a tube. An axial pulling force is applied to the shaft to break the tube out of the tube sheet, thereby allowing the tube to be removed.

Another prior art method relies on collapsing the tube by driving a sharp tapered tang in between a tube and the corresponding hole of the tube sheet so as to deform the end H:m gep\rp 6'compete\PS6511 Method and Device for Engaging a Bore.doc 14/04/05 3 of the tube into a profile. In this way, the hold on 8 the expanded or welded expanded tubes is broken allowing the C tube to be pulled out of the tube sheet.

Yet another method of removing tubes from a tube sheet is to 00 cut the tube inside the tube bore so as to reduce the wall thickness of the tube to such an extent that the restraint between the expanded tube and the tube sheet is broken.

\O

Still another method of removing tubes from a tube sheet C involves the use of a hollow shaft that is inserted into the tube to be extracted. The end of the hollow shaft that Cl is furthermost inside the tube is provided with a bifurcated or split end. A drawbar with a tapered conical end is drawn up from the furthermost end of the tube into the split end of the hollow shaft. This causes the split end of the hollow shaft to open. The outside of the hollow shaft is provided with grooves at the split end to grip into the interior of the tube. When sufficient gripping force has been applied, the tube becomes detached. This arrangement suffers from a variety of problems, the most serious of which is that it is extremely difficult to remove the drawbar and shaft from a tube in the event of jamming.

Several other problems exist with these known methods.

When a "spear" is used, the tapered threaded tip must be individually machined to match the diameter of a given tube to be removed. To allow machining of the tapered tip of the shaft, the shaft is typically constructed of a relatively soft steel material. The tapered tip of the "spear" is difficult to consistently harden to a desired quality. The shaft tips that are currently manufactured are thus rapidly blunted especially when cutting into tubes coated internally with hard deposits. When the tip is blunted the entire shaft is routinely scrapped, leading to a high degree of wastage.

H:-\osg\keep\Wec\complee\P565 II- Method and Device for Engaging a Bore doc 14/04/05 4 SBlunting of the tip of the shaft increases the already high amount of torque required to screw the shaft into the tube.

In the event of slippage whilst using a high torque machine wrench, the operator is endangered. To obviate the problems associated with slippage, large fixed machines 00 lacking portability, speed or adaptability are often used.

The efficiency of tube removal is thus greatly reduced.

The alternative to a machine wrench is the impact wrench or NO "rattle gun". These devices transmit a shock vibration to the operator and generate considerable noise, creating strain injury and hearing damage.

C-I There is a need for an alternative method of removing tubes from heat exchanger or boiler tube bundles.

It will be clearly understood that, although prior art use and publications are referred to herein, this reference does not constitute an admission that any of these form a part of the common general knowledge in the art, in Australia or in any other country.

In the statement of invention and description of the invention which follow, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features, but not to preclude the presence or addition of further features in various embodiments of the invention.

Throughout this specification the term "bore" is intended to denote an inside surface of a hollow member such as a pipe or tube; or an inside surface or diameter of a hole in a solid body such as a hole in a block of concrete or body of rock or metal structure.

Summary of the Invention According to a first aspect of the present invention, there is provided a device for engaging a bore comprising: H:Vkoc m\pqecicomplete\PS6511 Method and Device for Engagiag a Bore.doc 14/04/05 5 3 a collet having a first end, a second end, an outer surface, a threaded inner surface, and at least one slot c or split extending between two spaced apart points on the Scollet; and, 5 a tapered member having a first end and a second end, 00 the first end sized to be received within the second end of the collet, the second end of the tapered member having a cross-sectional area greater than the first end of the INO tapered member, the tapered member having an external surface correspondingly threaded to mate with the threaded inner surface of the collet, Swhereby, in use, the first end of the tapered member (1 is positioned within the second end of the collet and thereafter screwed into the collet so as to radially expand the collet bringing the outer surface of the collet into engagement with the bore.

Preferably, the outer surface of the collet comprises a means for gripping the bore. More preferably, the means for gripping the bore is one or more projections arranged to project or bite into the bore. The one or more projections may be sharpened and/or hardened to make it easier for the projections to bite into the bore or to break through any hard deposit that may be present in the bore.

In one embodiment, the means for gripping the bore comprises a plurality of parallel circumferential crests.

In another embodiment, the means for gripping the bore comprises a helical crest a screw thread). The use of a thread is preferred, as this makes removal of the collet from the bore easier, as the collet acts like a self-tapping screw.

Preferably, each crest is hardened to assist in cutting or "forming itself" into the bore.

In one embodiment, a turn of the helical crest has a profile comprising a first flank that faces the first end H:Voq\keepec=coWmpete\P56511 Method and Device for Engaging a Bore.doc 14/04/05 6 V) of the collet and is substantially planar, and a second flank that is concavely curved.

SIn an alternative embodiment, a turn of the helical crest has a profile comprising a first flank and a second flank, 00 where one of the first flank and the second flank lies in a plane that slopes relative to a longitudinal axis of the collet and another of the first and second flanks is INO substantially vertical to the longitudinal axis.

Preferably, the first flanks lies in a plane that slopes downwardly towards the first end of the collet.

Ci Preferably, the inner surface of the collet and the external surface of the tapered member are correspondingly buttress threaded, each buttress thread comprising a sloping face, a substantially vertical face, and a crest between the sloping face and vertical face. Preferably, the sloping faces of the buttress thread of the tapered member slope downwardly towards the second end of the tapered member whereby, in use, the application of an axial pulling force in the direction of the second end of the tapered member causes relative movement between the mating sloping faces of the inner surface of the collet and the outer surface of the tapered member so as to radially expand the collet. It will be recognized that application of an axial force in a reverse direction (ie toward the first end) will lead to a radial contraction of the collet.

Preferably, the external surface of the member tapers naturally outwards in the direction of the second end of the member at an angle of 0.1 to 10 degrees and, more preferably, an angle of 1.5 to 2.5 degrees, to the longitudinal axis of the tapered member.

Preferably, a connector is provided at the second end of the tapered member for connecting the tapered member to a force transmitting member. The force transmitting member may be any apparatus arranged to apply an axial load to the tube engaging device such as a shaft.

H:\osg\kikcp\ppci\complete\P56511 Method and Device for Engaging a Bore.dDc 14/04/05 7 SPreferably, in one embodiment the slot or split comprises a longitudinal slot or split that extends longitudinally Salong the collet.

5 In one embodiment, the split is one of a plurality of 00 longitudinal splits that divide the collet into a corresponding plurality of collet portions.

ND Preferably, the device further comprises a means for holding the collet portions together. In one embodiment the means for holding the collet portions together comprises an elastic member applied to the outer surface of C( the collet. In another embodiment, the means for holding the collet portions together is a circlip or flat clip. In yet another embodiment, the means for holding the collet portions together comprises a layer of flexible adhesive along the longitudinal splits of the collet.

In an alternate embodiment the slot or split comprises a helical split or slot that extends helically through the collet. Preferably in this embodiment the helical split or slot extends between and opens onto the first and second opposite axial ends of the collet. The helical split or slot can be a right hand or a left hand helical split or slot.

According to another aspect of the present invention, there is provided a method of engaging a bore, the method comprising: providing a collet having a first end, a second end, an outer surface, a threaded inner surface, and at least one slot or split extending between two spaced apart points on the collet; inserting a first end of a tapered member into the second end of the collet, the tapered member further comprising a second end with a cross-sectional area greater than the first end of the tapered member, the tapered member having an external surface correspondingly threaded to mate with the threaded inner surface of the collet; H:\rosg\kep\qc icompe\P5651 I Mdhod and Device for Egaging a Bore.doc 14/04/05 8 n positioning at least a portion of a collet into the bore of a tube; and, radially expanding the collet so as to bring the outer Ssurface of the collet into engagement with the bore by 5 screwing the first end of the tapered member into the 00 second end of the collet.

Preferably, the positioning at least a portion of the collet O into the bore occurs prior to inserting the tapered member into the collet. Alternatively, inserting the tapered member into the collet is conducted prior to positioning at Sleast a portion of the collet into the bore and prior (1 expanding the collet.

In another embodiment, expanding the collet is conducted prior to positioning the collet into the bore so as to form an expanded collet. In this scenario, the method further comprises the step of driving the expanded collet into the bore of the tube.

According to another aspect of the invention there is provided a collet comprising: a tubular body having a first end, an axially opposite second end, a threaded inner circumferential surface, a thread formed about an outer circumferential surface, and a helical slot or split extending between two spaced apart points along the tubular body, where one of the points is at the first or second end.

Brief Description of the Drawings The preferred embodiments of the present invention will now the described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates a first preferred embodiment of the present invention showing an isometric view of a collet and a tapered member at the end of a shaft; Figure 2 illustrates a side view of the device of Figure 1 in use after expansion of the collet and engagement H:iosgkeepeci\compete\P56511 I Method and Device for Engaging a Bore.doc 14/04/05 9 tt of a bore; Figure 3 illustrates a second preferred embodiment of the present invention showing an isometric view of a collet Ssplit into collet portions and held together using an elastic member, as well as a tapered member; 00 Figure 4 is a side view of the device of Figure 3 in use after expansion of the collet and engagement of the bore; and, \O Figures 5(c) and 5(d) illustrate alternative configurations of the collet.

SDetailed Description of the Preferred Embodiments of the (Ni Invention Preferred embodiments of the present invention are now described in detail in the context of the removal to a tube from a tube sheet of a boiler or heat exchanger. Here the embodiments engage the bore of the tube. It is to be clearly understood that embodiments of the method and device may equally be employed to engage a tube for inserting, then expanding a tube into a bore hole of a tube sheet or other equipment, in which case the preferred directions described below are reversed. Moreover, embodiments of the invention may be used to engage bores other than those of tubes or pipes, such as a bore formed in a block, or a piece of material such as a rock, concrete block or metal beam or structure. Indeed embodiments of the device may be constructed in the form of a stud or bolt to act as a replacement for an original threaded stud or bolt that is no longer able to threadingly engage its placement hole due to stripped or otherwise damaged thread in that hole. The disclosed embodiments are merely exemplary of the present invention which may be embodied in various forms. The specific structure, method steps, and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention.

H:V\rosgkep\peci\complete\P56511 ii- Method and Device for Engaging a Bore.doc 14/04/05 10 SA first embodiment of the device of the present invention is illustrated in Figures 1 and 2. With reference to Figure 1 there is provided a engaging device 10 comprising Sa collet 12 having a first end 13 for insertion into a bore 22 of a tube 24 and a second opposed end 15. The collet 12 00 has an outer surface 14, a threaded inner surface 16, and at least one split 18 extending along the length of the collet 12 for facilitating expansion of the collet 12. In INO Figure 1, the split 18 is a longitudinal split 18 and extends along the full length of the collet 12. It is to be understood that the longitudinal split 18 need not Sextend along the full length of the collet 12, provided (Ni only that the collet 12 is capable of sufficient expansion to bring the outer surface 14 of the collet 12 into gripping engagement with the bore 22 of a tube 24. As described in the Background section, it is common practice for heat exchanger tubes to have one or both ends expanded to form a seal with the holes in a tube sheet 11.

The tube 24 has an expanded end 27. The expanded inner end 27 of the tube 24 has an included angle of up to 2 degrees.

The collet 12 may be substantially cylindrical or frustoconical with an angle of taper matched to the included angle of the expanded end 27 of the tube 24. The use of a frustoconical collet is understood to improve the gripping force between the expanded collet 12 and the bore 22 of the tube 24. The collet 12 may equally have a parallel outer surface 14, as illustrated in Figure 1, and such a collet is particularly suitable for tubes 24 with expanded ends 27 having small included angles.

The outer surface 14 of the collet 12 is optionally provided with a means 20 for gripping the bore of a tube when the collet 12 is expanded in use inside the tube 24.

In the illustrated embodiment of Figures 1 and 2, the outer surface 14 of the collet 12 is threaded and the thread T 1 provides the means for gripping the bore of the tube The thread T 1 of the outer surface 14 of the collet 12 has a profile in cross-section comprising a plurality of wave- H:\rog\kec\spodiompptc\P565 1 Method and Device Lbr Engaging a Boredoc 14/04/05 11 Sshaped turns 19, each turn 19 comprising a hardened crest 21, a sloping first flank or face 23 and a concavely shaped second flank or face 25 as illustrated in Figure 2, Salthough it should be understood that other shapes can of 5 course be provided, such as, but not limited to, a convex 00 second flank.

The outer surface 14 of the collet 12 may equally be smooth ND with the gripping force exerted on the bore 22 of the tube 24 being provided by frictional resistance, as shown in the embodiment of Figure It is envisaged that the Sgripping force may be enhanced by coating the outer surface (Ni 14 with a high friction coefficient material such as rubber. Alternatively, the outer surface 14 of the collet 12 may be provided with a means for gripping the bore of the tube 20 in the form of a series of circumferential projections 51 and recesses 52, as illustrated in Figure a plurality of hardened or sharpened projections 56, as illustrated in Figure or a helical thread (ie, continuing helical crest T 1 as shown in Figure A thread is preferred, as the thread assists in removal of the collet (by screwing it out), if jammed. It is to be clearly understood that other thread profiles may equally be employed for the turns 19 such as any sharp crested or buttress thread.

The wave-shaped profile of the turns 19 illustrated in Figures 1 and 2 is designed to maximise the biting force of the outer surface 14 of the collet 12 on the bore 22 of the tube 24. To this end, each turn 19 has a positive rake.

The crest 21 of each turn 19 is hardened, typically to a hardness level greater than that of the material of construction of the tube 24. Hardening the crest 21 of the thread Ti assists in them biting into the bore 22 of the tube 24 when the collet 12 is expanded in use. The crests on the thread Ti may equally be sharpened, coated or include embedded hard material suited to sustaining the pressures generated.

H:rogM\kep\spc comp1e\P56511 I Method and Device for Engaging a BoredD 14/04/05 12 n The tube engaging device 10 further comprises a tapered member 30 for facilitating expansion of the collet 12. The tapered member 30 has a first end 32, a second end 34 and San external surface 36 correspondingly threaded to mate 5 with the threaded inner surface 16 of the collet 12. In 00 the illustrated embodiment in Figures 1 and 2, the crosssectional area of the tapered member 30 increases in the direction of the second end 34 of the tapered member with an angle of inclination of the taper in the order of 2 degrees. The included angle could equally be in the range of 1 to 5 degrees, preferably in the range of 1.5 to Sdegrees to the longitudinal angle of the tapered member (1 Moreover, in other applications of embodiments of this invention, for example when used as anchors in hard materials, the angle of the taper may lie within the range of 0.1 to 10 degrees.

Integrally formed with the second end 34 of the tapered member 30 is a connector 31 in the form of a pin 33 for connecting the tapered member 30 to a force transmitting member (not shown) typically a device for transmitting axial force to the tube 24 through the tube engaging device A shaft 40 is provided between the tapered member and the pin 33. It is to be clearly understood that connectors 31 other than the pin 33 may be used for attaching the tapered member to a force transmitting members As is best illustrated in Figure 2, the inner surface 16 of the collet 12 and the external surface 36 of the tapered member 30 of the first preferred embodiment of the present invention are provided with mating buttress threads T 2 and

T

3 respectively. The buttress thread T 3 of the outer surface 36 of the tapered member 30 has a plurality of turns 41, each turn 41 comprising a sloping face 43, a vertical face or flank 45 and a crest 44 between the sloping and vertical faces 43 and 45 respectively. The buttress thread T 2 of the inner surface 16 of the collet 12 has corresponding sloping faces, vertical faces and crests.

H:osgkeep\peci\competew\P565 11 Method and Device for Engaging a Bordoc 14/04/05 13 n The sloping faces 43 of the turns 41 of the thread T 2 of the tapered member 30 are inclined in the direction of the second end 34 of the tapered member 30. In the illustrated Sembodiment, the sloping face 43 has an angle of inclination 5 of between 30 and 60 degrees to the vertical with the 00 vertical face 45 being substantially perpendicular to the longitudinal axis of the collet 12.

IND When a pulling force is applied in the direction of the second end 34 of tapered member 30, a component of the n pulling force is transmitted radially outwardly via the Smating sloping faces 43 of the inner surface 16 of the (Ni collet 12 and the outer surface 36 of the tapered member This use of a "reverse" buttress thread is in complete contra-distinction to the use of a normal buttress thread, where the thrust of the pulling force would be transferred across mating vertical faces of the buttress threads to maximise transfer of the axial component of the pulling force. The reason behind this counter-intuitive use of a reverse buttress thread is that in using this arrangement, some of the axial pulling load is converted to a radial expansion force to further expand the collet 12 and to embed the collet 12 into the bore 22 of the tube 24. The mating sloping surfaces 43 provide a wedging action which also assists in maintaining the grip of the collet 12 on the bore 22 of the tube 24.

In some applications, depending on the relative size of the bore of the tube and the collet, this wedging action alone may suffice to bring the outer surface 14 of the collet 12 into gripping engagement with the bore 22 of the tube 24.

In other words, the collet 12 could be expanded using the tapered member 30 so as to provide a light grip on the bore 22 of the tube 24 whilst relying on the pulling force to cause further expansion of the collet 12. This method is particularly suited for tubes constructed of softer materials such as cupro-nickel, aluminium-bronze or copper.

However use of the collet 12 is not limited only to these or other softer materials. Indeed the collet 12 may be H:\rosjkccp\pewt\compcte\P565 ii- Mlbod ad Device for Engaging a Boredc 14/0405 14 tt used in gripping any ferrous, non ferrous or non metallic materials such as polymers, oxides, carbides, nitrides and borides.

A second preferred embodiment of the device of the present 00 invention is illustrated in Figures 3 and 4 where like reference numerals refer to like parts. In this second embodiment, two longitudinal splits 18 extend along the IND full length of the collet 12 dividing the collet 12 into two collet portions 50. If the collet 12 is provided with additional longitudinal splits 18, the collet will be Sdivided into a corresponding plurality of collet portions.

(1 The use of the collet portions 50 greatly reduces the amount of flexing required of the collet itself and should reduce the torque needed to expand the collet during the step of screwing in the tapered member 30. This is because the torque used to expand the collet is not wasted on deforming the collet itself.

One of the drawbacks of using a plurality of collet portions 50 is that if the portions become separated in use, they may fall into the tube, and this is a particular problem for heat exchangers with vertical tubes. To overcome this potential problem, the collet portions 50 are held together by any suitable means for holding the portion together, such as an adhesive that is capable of expansion or by vulcanising the portions together using an elastomeric compound along the longitudinal splits 18 of the collet 12.

In the illustrated embodiment of Figures 3 and 4, the collet portions 50 are held together using a rubber band, a circlip or a flat clip 56 positioned around the outer surface 14 of the collet 12 at the second end 15 of the collet 12. The rubber band 56 remains in place after insertion of the collet portions 50 into the bore 22 of the tube 24 and provides some frictional resistance against rotation of the collet 12 relative to the tube 24 prior to H:\mrosgq\keep\sp c complete\P56511 Method and Device for Engaging a Bore.doc 14/04/05 15 t engagement of the outer surface 14 of the collet 12 with the bore 22 of the tube 24.

SIn the second embodiment, the tapered member 30 does not include the integral shaft 40 and the connector 31 for 00 connecting the tapered member to a force transmitting member is in the form of a threaded connection i.e. a screw Cthread 35. The means for gripping the bore 22 in the IN second embodiment is the use of a thread T 1 on the outer surface 14 of the collet 12. The thread T 1 in this embodiment has a buttress profile as described above and best seen in Figures 3 and 4. The turns of the mating (1 threads T 2 and T 3 of the inner surface 16 of the collet 12 and the outer surface 36 of the tapered member 30 in the second embodiment have a screw thread which may also, but not prescriptively, include vee-form threads, saw-tooth threads and translating threads of the acme, stub-thread, worm, square thread, Dartelet self-locking and/or sinusoidal forms, including their variants.

The method of engaging a bore is now described in detail with reference to the embodiment of the bore engaging device 10 illustrated in Figures 3 and 4 and in the context of removing a tube 24 from a tube sheet 11. It is to be understood that embodiments of the device may equally be used to expand the end 27 of a tube 24 when inserting tubes into a tube sheet.

The second end 15 of the collet 12 is positioned onto the first end 32 of the tapered member 30 before or after insertion of the collet 12 into at least a portion of the bore 22 of a tube 24. Expansion of the collet 12 to engage the bore 22 of the tube 24 is effected after insertion of the collet 12 into the bore 22 of the tube 24. Once the collet 12 is inserted into the bore 22 of the tube 24, the collet 12 is expanded progressively by screwing the tapered member 30 further towards the first end 13 of the collet 12.

H:rosgpUep\speci:ompete\P565 II Method iand Device for Engaging a Bore.doe 14/04/05 16 n The tapered member 30 may be mechanically coupled to a force transmitting device or an intermediate shaft (not k shown) using the threaded connector 35 provided at the second end 34 of the tapered member 30. The force 5 transmitting device may be any suitable device capable of 00 generating an axial force such as a hydraulic or air cylinder, a mechanical screw, a lever, a cable powered winch, a sliding weight on an impact bar or vibratory INO impact device. The axial load could equally be generated using electro-magnetics or explosive jarring devices.

SWhen the collet 12 has been expanded sufficiently, the (Ni means 20 for engaging the bore of the tube 24 is brought into positive engagement with the bore 22 of the tube 24.

The rubber band 56 assists in restricting rotation of the collet 12 relative to the tube 24, as well as holding the collet portions 50 together. Rotation of the collet 12 relative to the bore 22 of the tube 24 is further restricted as soon as the hardened crests 21 of the turns 19 of the threaded outer surface 14 of the collet 12 become embedded in the bore 22 of the tube 24.

After the bore 22 of the tube 24 has been so engaged, an axial pulling force is applied in the direction of the second ends 34 of tapered member 30 so as to pull the tube 24 from the tube sheet 11. The shaft may be attached to a separate apparatus (not shown) arranged to apply the required axial pulling force to extract the tube 24 from the tube sheet 11.

The axial pulling force is transmitted through the shaft to the tapered member 30 to the collet 12 via the mating sloping faces of the buttress threads T 2 and T 3 respectively.

When sufficient axial pulling force is applied, the expanded end 27 of the tube 24 separates from the tube sheet 11 enabling the tube 24 to be removed. After the tube 24 has been removed, the force transmitting device may H:\rosg\keUep\speci\completeP5651 i Method and Device for Engaging a Bore.doe 14/04/05 17 Sbe unscrewed from the tapered member 30 and the collet portions 50 removed from the extracted tube 24. The collet c 12 may equally be retained on the tapered member 30 for the next use of the device 10. The collet portions 50 may be 5 re-used or discarded if damaged. The thread of the outer 00 surface 36 of the tapered member 30 is protected from damage during use of the tube engaging device 10 allowing the tapered member 30 to be readily re-used to remove or NO insert other tubes.

.*In the embodiments depicted in Figures 1-4, the slot or Ssplit 18 is depicted as extending longitudinally along the (1 length of the collet 12. However in alternative embodiments, for example as depicted in Figures 5(a) and the slot or split can be in the form of a helical slot or split 18. Here, the slot or split extends helically between two points A and B on the collet 12. It is considered most efficacious if these two points lie at the opposite ends 13 and 15 of the collet 12 in which case the helical slot or split 18 will open onto the opposite ends 13 and 15. However, in other embodiments, the helical split 18 may extend between one point on the first end 13 or second end 15, and a second point intermediate the first and second ends 13 and 15. It is envisaged that the helical split 18 will have a pitch greater than that of any thread T 1 and/or

T

3 formed on the collet 12. In the embodiment in Figure the collet 12 is provided with a helical thread T1 on a circumferential surface 14 having a crest that acts as a cutting edge to cut into the bore 22. In this regard, in use, when the member 10 is initially screwed into the collet 12, the collet 12 will spin about its longitudinal axis until it is expanded radially sufficiently so that its outer surface 14 contacts the inside surface of the tube 10. The collet 12 will then turn within member 10 with the thread T 1 effectively cutting a thread into the bore 22.

Forming the helical split 18 to run in a counter sense to the thread T1 results in the collet 12, being self locking as the rotation for removal of the helical split collet applies a torque to the collet 12 causing it to expand ii- Method md Device fbr Eagaging a Boredoc 14/04/05 18 radially thereby increasing grip on bore. This can be of O benefit when the device is used for the purposes of gripping a hole in a material such as for example application as a Srock bolt; or other applications requiring security or 5 tamper proof fixings, or for the threaded hole remediations 00 and the like.

As suggested above, embodiments of the device 10 may be used to form anchors in hard materials such as masonry, rock and

NO

metal, and additionally used as replacement bolts or studs for holes having damaged threads. In both embodiments, the Smethod of operation and physical structure of the device is the same as described above in relation to the embodiments used for extracting tubes in a heat exchanger. In the case of application in holes in hard materials having no threads, eg holes in masonry or rock, the collet 12 is engaged with the tape member 30 but only to the extent so as to not expand the outer diameter of the collet to beyond the inner diameter of the hole into which it is to be inserted; the ensemble of the collet 12 and thread member 30 is then inserted into the hole with the collet 12 first, then the threaded member is turned to effect a radial increase in the diameter of the collet 12 thus gripping the interior surface of the hole in which it is disposed. Likewise, when used for the purposes of say placing a bolt in a hole having a damaged or stripped thread, an identical procedure can be used particularly using a collet 12 of the type having a helical crest (ie helical thread) T 1 In such an embodiment, the thread member 30 would remain engaged with the collet 12 so as to act as the shank of a bolt. Additionally, the connector 33 may be reconfigured to be in the form of a conventional bolt head that extends transversely beyond the shank.

Now that the preferred embodiments of the present invention have been described in detail, it will be apparent that embodiments of the present invention have a number of advantages over the prior art, including: The use of an expanding collet avoids the need to cut a thread as normally required for tube extraction, H:\ros\kcqp\pecicompet\eP565 I Method and Device for Engaging a Bore.doc 14/04/05 19 n thereby eliminating a wasteful, time consuming operation.

The use of an expanding collet greatly reduces the cqtorque required to produce the grip that is needed to remove Sthe tube from its containment hole.

5 The reduction in torque means that lighter, 00 quieter and more portable equipment can be utilised in tube extraction giving less stress to operators.

The reversed buttress thread maintains the O gripping force during extraction.

The collet and tip are exchangeable and removable, thereby reducing parts wastage.

The collet does not need to penetrate deeply to (Ni produce grip thereby reducing the possibility of damage to the tube plate bore.

The collet system is applicable to soft materials.

The design and orientation of the tapered components means that these are self releasing or can be easily removed particularly in the event of failure of a component.

Numerous variations and modifications will suggest themselves to persons skilled in the relevant art, in addition to those already described, without departing from the basic inventive concepts. For example, once the collet is expanded into place, the tapered member could be detached from the shaft and attached to another device capable of generating the required extraction force. In the illustrated embodiments, the tapered member could equally increase in cross-sectional area towards the expanded end of the tube. Using this arrangement, the collet is still positioned on the end of the tapered member having the smaller cross-sectional area. The only difference is that the collet is expanded by pulling the tapered member towards the end with the smaller cross-section by screwing the tapered member anti-clockwise for a right-hand thread. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

H:rosagep\pecicompete\P565 11 Method and Device for Engaging a Bore.do 14/04/05

Claims

2. The device according to claim 1 wherein the outer surface of the collet comprises a means for gripping the bore.
3. The device according to claim 2 wherein the means for gripping the bore is one or more projections arranged to project or bite into the bore.
4. The device according to claim 3 wherein the means for gripping the bore comprises a plurality of parallel circumferential crests. The device according to claim 3 wherein the means for gripping the bore comprises a helical crest.
6. The device according to claim 4 or 5 wherein each crest is hardened to assist in cutting or forming itself into the bore. H:\ros\kep\pccicomplte\P565 11 Method and Device for Engaging a Bore.doc 14/04/05 21 tt 7. The device according to claim 5 or 6 wherein a turn of the helical crest has a profile comprising a first flank that faces the first end of the collet and is Ssubstantially planar, and a second flank that is concavely 5 curved. 00
8. The device according to claim 5 or 6 wherein a turn of the helical crest has a profile comprising a first INO flank and a second flank, where one of the first flank and the second flank lies in a plane that slopes relative to a longitudinal axis of the collet and another of the first and Ssecond flanks is substantially vertical to the longitudinal C( axis.
9. The device according to claim 8 wherein the first flanks lies in a plane that slopes downwardly towards the first end of the collet. The device according to anyone of claims 1 9 wherein the inner surface of the collet and the external surface of the tapered member are buttress threaded, each buttress thread comprising a sloping face, a substantially vertical face, and a crest between the sloping face and vertical face.
11. The device according to claim 10 wherein the sloping faces of the buttress thread of the tapered member slope downwardly towards the second end of the tapered member whereby, in use, the application of an axial pulling force in the direction of the second end of the tapered member causes relative movement between the mating sloping faces of the inner surface of the collet and the outer surface of the tapered member so as to radially expand the collet; and, application of an axial force in the direction of the first end of the tapered member cause relative movement between the mating sloping surfaces of the inner surface of the collet and the outer surface of the tapered member to radially contract the collet. II Method and Device for Engaging a Boredoc 14/04/05 22 n 12. The device according to anyone of claims 1 11 wherein the external surface of the member tapers outwards in the direction of the second end of the member at an Sangle of 0.1 to 10 degrees to the longitudinal axis of the tapered member. 00
13. The device according to anyone of claims 1 11 wherein the external surface of the member tapers outwards INO in the direction of the second end of the member at an axis of the tapered member, at an angle of 1.5 to 2.5 degrees to the longitudinal axis of the tapered member. (1 14. The device according to any one of claims 1 13 wherein a connector is provided at the second end of the tapered member for connecting the tapered member to a force transmitting member. The device according to any one of claims 1 14 wherein the slot or split comprises a longitudinal slot or split that extends longitudinally of the collet.
16. The device according to claim 15 wherein the split is one of a plurality of longitudinal splits that divide the collet into a corresponding plurality of collet portions.
17. The device according to claim 16 further comprising a means for holding the collet portions together.
18. The device according to claim 17 wherein the means for holding the collet portions together comprises an elastic member applied to the outer surface of the collet.
19. The device according to claim 17 wherein the means for holding the collet portions together is a circlip or flat clip. The device according to claim 17 wherein the means H:\rong~eTp\%pc icompIete\?565 I Method and Device for Eaging a Boredc.c 14/04/05 23 for holding the collet portions together comprises a layer Sof flexible adhesive along the longitudinal splits of the Scollet. 00 5 21. The device according to anyone of claims 1 14 wherein the slot or split comprises a helical split or slot that extends helically through the collet.
22. The device according to claim 22 wherein the helical slot or split runs in a counter sense to the helical n crest.
23. A method of engaging a bore, the method comprising: providing a collet having a first end, a second end, an outer surface, a threaded inner surface, and at least one slot or split extending between two spaced apart points on the collet; inserting a first end of a tapered member into the second end of the collet, the tapered member further comprising a second end with a cross-sectional area greater than the first end of the tapered member, the tapered member having an external surface correspondingly threaded to mate with the threaded inner surface of the collet; positioning at least a portion of a collet into the bore of a tube; and, radially expanding the collet so as to bring the outer surface of the collet into engagement with the bore by screwing the first end of the tapered member into the second end of the collet.
24. The method according to claim 23 wherein the positioning at least a portion of the collet into the bore occurs prior to inserting the tapered member into the collet. The method according to claim 23 wherein inserting the tapered member into the collet is conducted prior to positioning at least a portion of the collet into the bore Hrxosg\kcp\spci\compIete\P6511 Method and Device for Engaging a Bore.doc 14/04/05 24 n and prior expanding the collet. S26. The method according to claim 23 wherein expanding the collet is conducted prior to positioning the collet into the bore so as to form an expanded collet. 00
27. A method according to any one of claims 23-26 further comprising maintaining the first end of the tapered INO member in the collet. S28. A method according to any one of claims 23-27 Sfurther comprising providing a shank extending from the (1 second end of the tapered member and head at an end of the shank shaped to facilitate engagement with a torque imparting tool.
29. A collet comprising: a tubular body having a first end, an axially opposite second end, a threaded inner circumferential surface, a thread formed about an outer circumferential surface, and a helical slot or split extending between two spaced apart points along the tubular body, where one of the points is at the first or second end.
30. The collet according to claim 29 wherein one of the points is at the first end and the other point is at the second end.
31. The collet according to claims 29 and 30 wherein the helical slot or split runs in a counter sense to the thread on the outer circumferential surface.
32. A device for engaging a bore substantially as herein described with reference to and as illustrated in the accompanying drawings.
33. A method for engaging a bore substantially as herein described with reference to and as illustrated in the accompanying drawings. H: sg\kep\peci\conete\P5651 I Method and Device for Engaging a Bore.do 14/04/05 25
34. A collet substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 1 8 t h day of April 2005. 00 ALTRUM PTY LTD 0 By Its Patent Attorneys 0 GRIFFITH HACK CI Fellows Institute of Patent and Trade Mark Attorneys of Australia. H:\rosg\keep\speci\complete\P56511 Method and Device for Engaging a Bore.doc 18/04/05