WO1995022431A1

WO1995022431A1 - Hydraulic apparatus

Info

Publication number: WO1995022431A1
Application number: PCT/GB1995/000270
Authority: WO
Inventors: David John Hughes; Kenneth Douglas Mercer
Original assignee: Hydra-Tight Limited
Priority date: 1994-02-22
Filing date: 1995-02-10
Publication date: 1995-08-24
Also published as: GB2286635A; GB9403375D0

Abstract

Apparatus (20) (Figure 1(a)) for forcing apart apertured bodies, such as separating frictionally interlocked turbine discs (11, 12) which have aligned apertures (1911, 1912) therein, comprises local and remote sleeves (33, 35) which are coupled axially by tie bars (67) and locating transducer (60) which sets their relative positions in the apertures in which they are disposed from one end. Each sleeve has a tapered internal wall (33, 38) and carries a tapered plug (34, 39). The plugs are connected by coaxial control rods (52, 54) to actuation transducer (50) which also serves with the locating transducer (60) to wedge the plugs into their sleeves by forcing them apart axially whilst the sleeves are held with respect to each other by locking transducer (60), causing the sleeves to expand radially into frictional engagement with the apertures. Unlocking transducer (60) permits transducer (50) to force both the wedged plugs and sleeves apart to separate the discs (11 and 12). Transducer (50) is double-acting and reversing its stroke unwedges the plugs from the sleeve permitting their removal from the separated discs. In an alternative embodiment (300, Figure 3(a)) the sleeves may be separated and inserted through opposite ends of a pair of apertures.

Description

Hydraulic Apparatus

This invention relates to forcing apart a pair of bodies by applying a separating force between them, and in particular to apparatus for effecting such separation when the bodies have aligned apertures therein and by which the separating force can be applied to the bodies along the line of the apertures.

It is known, for example, in a gas turbine structure to have a stack of two or more rotor discs which are located with respect to each other by frictionally engaged projections and recesses extending along, and centred on, the axis of rotation of the rotor. Such discs may be further assembled with retaining bolts or tie-bars, threaded through aligned apertures arrayed about, and extending parallel to, said axis of rotation. The periphery of each rotor disc may support an array of relatively fragile alloy turbine blades which make access to the interface between stacked discs, to force them apart by driving wedges in radially, difficult. Furthermore such peripheral blades make attachment of pulling devices to any disc difficult and often permit direct access only to the aperture of one body.

It is also known to force apart a pair of bodies, such as pipes, incorporating flanges which are normally bolted together, to form a joint between the flanged bodies, or bolted to an object such as a valve disposed between the flanged bodies. Such pair of body flanges may also have aligned apertures therein, notwithstanding that the aligned aperture pair may be separated by an intervening non-apertured object. It is known to force apart such flanges by securing relatively displaceable parts to them by inserting components of said parts into the apertures and rotating or screwing them against the aperture walls to effect an interengaging or interference fit therewith, whereby separation of the components is accompanied by separation of the flanges. Such methods risk damage to the flange apertures and are limited in the degree of separating force that can be transmitted by the relatively small extent of interengagement resulting from manual securing. Such known devices for flange separating also require access to both ends of the aligned apertures and have no application to separating frictionally interlocked bodies discussed above.

It is an object of the present invention to provide apparatus for forcing apart a pair of bodies having aligned apertures therein that mitigates disadvantages and limitations of known forcing apparatus.

According to the present invention apparatus for forcing apart a pair of bodies having aligned apertures therein comprises (D a local part having a local sleeve arranged to be disposed in one body in one of the aligned apertures, the local sleeve having a longitudinal axis extending along the aperture and an inner wall tapered over at least part of its axial length and containing a correspondingly tapered local plug, (2) a remote part having a remote sleeve arranged to be disposed in the other body in the other of said aligned apertures in line with the local sleeve, the remote sleeve having a longitudinal axis extending along the aperture and an inner wall tapered over at least part of its axial length and containing a correspondingly tapered remote plug, (3) locating means arranged to dispose said local and remote sleeves in fixed positional relationship with respect to each other in the relatively fixed bodies and move each plug within its respective sleeve to a wedged position at which the sleeve is expanded by the plug into frictional engagement with the aperture and the plug is wedged against further motion along the sleeve, (4) actuation means operable to force the sleeves apart substantially along the line of the apertures to separate the bodies, and (5) release means operable to move the local and remote plugs with respect to their sleeves out of said wedged positions to permit said sleeves to contract from said frictional engagement with the apertures and to permit each sleeve and its plug to be removed from the respective body aperture.

The apparatus may be configured such that the remote part is connected to said local part by way of the locating means and both said parts are arranged to be disposed in, and removed from, contiguous apertures by way of one body, or, alternatively, such that the remote part is separate from the local part and each sleeve, with its associated plug, is arranged to be disposed in, and removed from, its respective aperture by way of an aperture end remote from the other aperture.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:-

Figure 1 (a) is a sectional elevation through a pair of frictionally interlocked bodes to be separated and apparatus in accordance with a first embodiment of the present invention comprising connected local and remote parts operationally disposed in aligned apertures of the bodies from one aperture end thereof, Figure 1 (b) is a schematic sectional elevation through the apparatus of Rgure 1 , illustrating the principal components thereof schematically.

Figures 2(a) to 2(d) are schematic sectional elevations, similar to Figure Kb), of alternative forms of this first embodiment of the invention,

Figure 3(a) is a sectional elevation, in the schematic style of Figure 1 (b), of a second embodiment of the present invention comprising separate local and remote parts disposed in aligned apertures of the bodies from opposite ends thereof, and

Figures 3(b) to 3(f) are schematic sectional elevations similar to Figure 3(a) of alternative forms of the second embodiment of the invention.

Referring to Figure 1 , two bodies 1 1 , 12 comprise part of a stack of such bodies which represent a rotor of a turbine. The rotor, and each body thereof, is symmetrical about an axis of rotation 3 and adjacent bodies are frictionally interlocked at annular faces 14, 15 defined by projections and recesses 17, 18 respectively extending along, and centred on, the axis 13.

Disposed radially outwardly of the frictional interlocking are a plurality of axially extending through- apertures 19 of circular cross-section arrayed about axis 13, only one such aperture being shown in the Figure in relation to each body. At each position about the axis 13, the through apertures are aligned with each other, being designated 19,, and 19₁₂ for bodies 1 1 and 12 and provide, in operation, a means for locating a bolt or stud member (not shown) to secure the bodies together to prevent relative rotational and axial separation.

In order to maintain any particular body, the rotor as a whole is removed from the machine and supported with the axis 13 vertical. Then, each body is lifted from the remaining bodies of the rotor stack by drawing it vertically. In accordance with the present invention, each set of aligned apertures 19 has disposed in relation thereto apparatus indicated generally at 20 for forcing apart the pair of bodies in accordance with a first embodiment of the present invention.

The apparatus 20 comprises a local part, shown generally at 21 , a remote part, shown generally at 22, locating means shown generally at 23, actuation means shown generally at 24 and release means shown generally at 25.

The local part 21 comprises a local sleeve 30 arranged to be disposed in operation in the aperture 19,, of body 1 1 which is accessible, and has a longitudinal axis 31 extending along, and shared with the aperture. The sleeve has a substantially cylindrical external cross-section which conforms to that of the aperture and has an inner wall 32 which for at least part 33 of the axial length is tapered and contains a correspondingly tapered local plug 34.

The remote part 22 comprises a remote sleeve 35 arranged to be operatively disposed in the aperture 19,₂ of body 12 and has a longitudinal axis 36 extending along, and shared with the aperture 19,₂ and axis 31 of the local sleeve. The remote plug has an external cross-section that conforms to that of the aperture 19,₂ and able to pass along aperture 19,, and has an inner wall 37 which, for part 38 of its axial length, is tapered and contains a correspondingly tapered remote plug 39.

The remote plug has a non-tapered extension forming a flange-like abutment means 40 of such radial dimension as to overlie the end of the local sleeve 30.

The local and remote plugs 34 and 39 are tapered in an opposite sense to each other, narrowing in cross-sectional area in an axial direction away from each other. Each of the sleeves 30 and 35 is also slit at at least one location about its periphery by a radial through-aperture extending axially for at least part of the length of the sleeve and including said internally tapered part, as shown for example, at 41. Each plug is movable axially in relation to the containing sleeve such that when moved into the sleeve the tapered surfaces mate and cause the sleeve to expand radially into engagement with the containing aperture which resists further expansion and the plug becomes wedged against further movement.

The locating means 23 connects the remote part to the local part such that both may be inserted into, and removed from, the aperture 19,,, be disposed axially with respect to each other in the interlocked bodies at such positions as to permit separation of the bodies, and be placed into frictional engagement with the aperture walls so that separation of the interlocked bodies can be effected by the actuation means 24 which forces the sleeves apart either directly or by way of the plugs. Before describing the locating means in greater detail it is appropriate to describe the actuation means 24.

The actuation means 24 comprises an actuation linear displacement transducer 50, conveniently abbreviated to actuation LDT, in the form of a hydraulic piston and cylinder arrangement disposed in line with the plugs adjacent the end of the local sleeve remote from the remote sleeve. The transducer has a first transducer element, cylinder body 51 , fixed in relation to the local plug by way of local control rod means 52 comprising a tubular member coaxial with longitudinal axis 31. A second transducer element, piston 53, is axially displaceabie with respect to the cylinder body and is coupled to the remote part 22 by remote control rod means 54 in the form of a single rod extending coaxially along the tubular member 52 in sliding relationship therewith. As shown, the remote control rod is connected to the remote plug 39 at 55 so as to transmit force thereto in both axial directions. The cylinder body 51 includes a supply duct 56 by way of which hydraulic fluid at elevated pressure is supplied to chamber 57, which pressure on the transducer elements displaces them relative to each other in a first axial sense and is transmitted to the plugs to force them apart.

Reverting to the locating means 23, this comprises a locating linear displacement transducer, conveniently abbreviated to locating LDT, 60 in the form of a hydraulic piston and cylinder arrangement disposed adjacent an end flange 30' of the local sleeve remote from the remote sleeve. The transducer has a first transducer element, annular piston 61 , arranged to bear on the sleeve flange in an axial direction, and a second transducer element, annular cylinder body 62, axially displaceable with respect to the piston by pressure in chamber 63 of hydraulic fluid admitted by way of duct 64.

Stop means 65 limits the relative axial displacement of piston and cylinder body and the cylinder body is connected to the remote sleeve by tie means 66 extending axially of the local sleeve. The tie means 66 comprises at least one tie bar 67 contained within the radial thickness of the local sleeve wall, any other tie bars (not shown) being arrayed about the longitudinal axis. If the local sleeve is slit along all or part of its length to flange 30' the tie bars(s) may be disposed to extend along such slit(s).

The annular cylinder body 62 surrounds slidably the local control rod 52 and may offer lateral, or radial, support to the control rods and actuation means 24.

The locating means 23 also includes a further locating LDT, indicated at 68, but which is conveniently provided by the actuation LDT 50.

The further locating LDT thus has its first transducer element, cylinder body 51 , fixed to the local plug 34 by local control rod 52 and its second, axially displaceable transducer element 53 connected to the remote plug by remote control rod 54.

The locating means also includes locking means, valve 69, which is able to be locked to prevent the transducer elements 61 , 62 of the locating LTD 60, and thus the sleeves, from being displaced axially by the forces exerted on the plugs by the further locating LDT, or indeed the actuation means as such, and to be unlocked to permit the elements to be so displaced.

Thus with the local sleeve 30 introduced into aperture 19,, to the extent permitted by flange 30' and with remote sleeve 35 introduced into aperture 19,_2> with the plugs disposed towards each other and out of contact with the tapered sleeve walls, the locating LDT is operated by introducing fluid at elevated pressure into chamber 63 by way of valve 69 to dispose the remote sleeve at such axial position with respect to the local sleeve, limited by stop means 65, that the transducer elements are separated by at least the distance required for forcing apart the bodies 1 1 and 12. The locking means 69 is operated to seal the chamber 63 with the fluid therein such that the elements are unable to be displaced relative to each other axially. The further locating LDT 68 (actuation LDT 50) is operated by introducing hydraulic fluid at elevated pressure into the chamber 57 which forces piston and cylinder body apart axially and also, by way of the control rods, the remote and local plugs. Because the sleeves are locked from axial movement relative to each other the plugs are driven along their respective sleeves to expand the sleeves with such axially separating force that when the sleeves are expanded into frictional engagement with the aperture walls and the plugs, unable to effect further expansion, become wedged against further axial motion.

Notwithstanding that the further locating LDT is also the actuation LDT, the locking means 69 prevents the axial forces exerted on the plugs from acting to separate the sleeves axially.

Thus to effect forcing apart of the bodies, the locking means 69 is unlocked, that is the chamber 63 is vented, permitting the axial force generated by the actuation LDT to act by way of the plugs and expanded sleeves on the bodies to separate them axially. Such separation, and the consequential separation of the sleeves secured in the body apertures, is accommodated by relative displacement of the elements 61 , 62 of the locating LDT and displacement of fluid from chamber 63. Preferably, but not essentially, the fluid in chamber 63 is vented by way of a resistive restrictor (not shown) so that in the event of the frictional interlock between the bodies at 14, 15 breaking suddenly, the fluid in chamber 63 acts as a buffer to retraction of the element and thus dampens any shocks.

Having separated the bodies with the local and remote parts anchored to the bodies, release means 25 is operated to permit their removal.

The release means 25 comprises a release linear displacement transducer, herein referred to as release LDT, which is indicated generally at 69. The release LDT is provided by a hydraulic piston and cylinder arrangement disposed in line with the plugs and conveniently is provided by the actuation LDT 50, the latter comprising a double acting arrangement in which the piston body 51 is arranged to define with piston 53 a further chamber 70 connected to duct 71 by which hydraulic fluid may be supplied or vented.

Operation is effected by supplying fluid at elevated pressure to the chamber 70 such that the piston 53, and remote control rod 54 is displaced axially with respect to the cylinder body 51 at local control rod 52 in an opposite relative directional sense to that of locating or actuation, drawing the plugs toward each other and out of the wedged positions in the respective sleeves whereby the sleeves can retract radially and be removed axially from the apertures.

Preferably, the remote plug 39 is arranged to be displaced from the wedged position in preference to the local plug, possibly by choice of material or length or angle of taper, in a direction towards the local plug such that upon displacement the abutment means 40 abuts the end of the local sleeve and the force exerted between the transducer elements 53 and 51 by the fluid pressure in chamber 70 acts between the local sleeve and its plug to displace the latter from its wedged position. By such arrangement it is possible to apply sufficient pressure to the transducer to release only the remote plug and thereafter to release the pressure in the chamber 70, whereby the body 1 1 containing the local part may be lifted, with the remote part, away from the body 12. For such purpose, and with the local sleeve 30 securely located in aperture 19,, by local plug 34, the release LDT/actuation LDT 50 may be provided with a lifting shackle 72.

Resumed or further fluid pressure in chamber 70 and reaction of the remote plug against the local sleeve displaces the local plug out of its wedging position in the sleeve, permitting the sleeve to contract radially and the local part to be removed from aperture 19,, with the remote part.

It will be appreciated that where such apertures are offset radially from the axis of the bodies along which separation is to be effected, corresponding apparatus located in other apertures about that axis may be operated simultaneously or multiplexed both in relation to locating and actuation means.

It will be appreciated that apparatus as described above and comprising a plurality of functionally interrelated elements may take a number of different forms, and some of these may be described, for convenience and clarity, in relation to a schematic representations.

Figure Kb) shows such a schematic representation of the apparatus 21 of Figure 1 (a), corresponding parts being given the same reference numbers. No additional description is necessary.

Referring to Figure 2(a) which shows schematically a first alternative form 80 of the apparatus 20 in which corresponding components are given corresponding reference numbers, the remote part 22 is connected to the local part 21 by way of locating LDT 60 and tie means 66. The remote sleeve 35 has internally tapered walls portion 38 and correspondingly tapered remote plug 39. The local sleeve has internally tapered wall portion 33 and correspondingly tapered local plug 34. Actuation means 24 comprise a double acting hydraulic actuation linear displacement transducer 50, (corresponding to transducer 50) which is disposed in line with the plugs with the first transducer element, cylinder 51 , formed between the plugs and operatively fixed in relation to the local plug by a local control rod 52,. The second transducer element, piston 53,, is connected to the remote plug 39 by remote control rod 54,.

It will be seen that the actuation LDT may act in exactly the same manner as the transducer 50 in Figures 1 and 2, in comprising also part of the locating means 23 and the release means 25, subject to the supply of hydraulic fluid to the cylinders by way of fluid lines (not shown) extending through the local plug or possible the local sleeve wall.

Figure 2(b) is similar to that of Figure 2(a) but shows a form 90 which differs from the form 80 in that actuation (and release) LDT 50₂ has the cylinder body formed at 51₂ in the body of the local plug, being inherently fixed in relation thereto and with the piston 53₂ connected by remote control rod 54₂ to remote plug 39.

It will be appreciated that in the form 80 or 90, the first transducer element provided by the cylinder body 51 , or 51₂ may be fixed to, or formed in, the remote plug.

In the forms 20, 80 and 90 described above, the local and remote sleeves and plugs are tapered in a sense that the cross-section of one narrows in a direction away from the other such that forcing the plugs apart in order to separate the bodies also increases the wedging between the plugs and their respective sleeves.

It will be appreciated that the locating means, insofar as it functions to dispose and hold the plugs wedged in their sleeves may be separated from the actuation means, as may the release means.

If the locating means is separated from the actuation means in respect of disposing and holding the plugs in their wedged positions, the sense of the tapers in the sleeves and plugs may be reversed, as shown in Figure 2(c) in the further alternative form 100. In this arrangement the remote sleeve 135 and remote plug 139 have a taper which narrows in cross-section towards the local sleeve 133, which likewise has a taper narrowing in cross-section towards the remote sleeve. Locating means 23 comprises a locating LDT 160 having a first transducer element, cylinder body 162, coupled to the remote sleeve by tie means 166 and second transducer element, piston 161 , bearing on the local sleeve. The transducer elements define a fluid chamber 163. The locating means also comprises a further locating LDT 168 in the form of hydraulic piston and cylinder arrangement having a first transducer element, cylinder body 168,, fixed in relation to local plug 134 by local control rod 152 and a second transducer element, piston 168₂, connected to the remote plug by remote control rod 154 and axially displaceable relative to the cylinder body by hydraulic fluid pressure in chamber 168₃. The further locating LDT 168 is a double acting arrangement, the cylinder body and piston also forming transducer elements of a release LDT 125 and defining a fluid chamber 125,. Thus with the sleeves held by the relatively disposed transducer elements 162 and 163 fluid pressure in chamber 168₃ forces the plugs towards each other and into wedged positions within the tapered portions of the sleeves which are then in frictional engagement with the body apertures.

The locating LDT 160 is also double acting and the transducer elements 161 and 162 define a second fluid chamber 157, together comprising an actuation LDT 150.

This transducer has the first element 162 fixed by the tie means to the remote sleeve and the second element 161 is fixed to the local sleeve such that fluid pressure in chamber 157 forces the sleeves axially apart by way of the tie means, the chamber 168₃ being permitted to bleed as the sleeves and their wedged plugs are forced apart.

It will be understood that in the above described forms further variations may be made. For instance where first and second transducer elements are shown defined by hydraulic cylinder body and piston respectively, they may be provided by piston and cylinder body respectively if appropriate.

Also, where the locating means, the locating LDT and further locating LDT, is shown disposed without the local sleeve and acting on one end thereof, if the sleeve is appropriately dimensioned, the locating LDT may be disposed within the local sleeve and bearing on suitably positioned inwardly extending abutment surfaces and additionally or alternatively the any/or all of separate or combined further locating LDT, actuation LDT and release LDT may be disposed within the sleeve.

It will also be understood that any or all of the linear displacement transducers described above may be formed other than as hydraulic piston and cylinder arrangements and numerous equivalents exist within the art. By way of example, Figure 2(d) shows a schematic representation of a fourth alternative form 200 of the apparatus 20 of Figure Kb). The apparatus 200 corresponds to the apparatus 20 in respect of all but the forms of the linear displacement transducers, and all components corresponding to those in apparatus 20 are given like reference numerals.

In the apparatus 200 the locating linear displacement transducer (LDT) 260, corresponding to locating LDT 60, comprises a first transducer element, spring 261 , arranged to bear on a flange 30' of local sleeve 30 and second transducer element, ring 262, which is connected to tie bar 66. The spring is arranged to hold the transducer elements at such distance that they can move together in operation by at least the distance required of the sleeves in separating the bodies.

Locking means 269, in the form of a removable pin or screw, extends between the ring 262 and sleeve flange 30' to inhibit relative movement of the transducer elements, and separation of the sleeves, until desired.

The plugs 36 and 39 are connected to coaxially extending control rods 52 and 54 which terminate in parallel, radially extending flanges 251 and 253 respectively. The flange 251 has arrayed about the axis of the control rod a plurality of holes 254 with threaded bores and the flange 253 has a corresponding plurality of holes 255 with plain bores. A plurality of screws 257 in threaded engagement with holes 254 extend by way of holes 255 to flanged heads 258 which bear on the flange 253.

The flanges 251 , 253 and screws 257, provide further locating LDT 268, rotation of the screws drawing the flanges together and forcing the plugs apart and into their wedged positions within the sleeves to the extent permitted by the locking means 269. The flanges 251 , 253 and screws 257 also provide actuation LDT 250 and, when locking means 269 is unlocked, continued rotation of the screws forces the flanges, and thus the sleeves and bodies, apart.

The flange 253 connected to the remote control rod also contains an array of tapped through-holes 270 which overlie the flange 251 and contain screws 270'. The flange 251 , 253 and screws 270' provide a release LDT. Rotation of the screws 270' causes them to bear upon flange 251 so as to force the flanges apart axially and the plugs towards each other.

The apparatus 200 is exemplary only of the ability to provide the linear displacement transducers by other than hydraulic piston and cylinder means and is open to many variations as to how linear displacement may be effected by providing mechanical means alone or even in combination with a fluid operated transducer.

The forms of apparatus described hereinbefore have the advantage of requiring access to one aperture only of a pair of bodies. Where access is available conveniently to both apertures independently, that is, from opposite ends, an alternative embodiment of apparatus may be employed. Such conditions may be expected in conjunction with flanges if joint in ridges pipes which have to be forced apart temporarily to replace a gasket or seal or some solid, unapertured body such as a valve disposed between the aligned, but not contiguous, apertures.

Referring to Figure 3(a) the apparatus 300 shares many components with the apparatus 20 of Figure Kb) and such components are given like reference numerals. To avoid repetition, the following description will be confined mainly to the differences.

In addition to the local sleeve 30 having a flange 30' to abut the body at the end of its aperture the remote sleeve 35 has a corresponding sleeve flange 35'. Actuation means 24 is provided by actuation LDT 50 connected to local plug 34 by local control rod 52 and coupled to the remote plug 39 by remote control rod 54. The remote control rod terminates in an abutment surface 340 which is adapted to bear on the remote plug and/or sleeve to apply forces in an axial direction away from the local sleeve but is not otherwise connected thereto.

Locating means 23 comprise a local locating linear displacement transducer (LDT) 360, disposed adjacent the flange 30' at the end of the local sleeve remote from the remote sleeve and a remote locating LDT 360- disposed adjacent a flange 35' at the end of the remote sleeve 35, both conveniently comprising annular hydraulic piston and cylinder devices. The local locating LDT 360, has a first transducer element 361 , arranged to bear on the local sleeve in an axial direction and a second transducer element 362,, axially displaceable with respect to the first element in a first directional sense, away from the remote sleeve, connected to the local plug by way of the local control rod 52. The remote locating LDT 360₂ has a first transducer element 361₂ arranged to bear on the remote sleeve in an axial direction and a second transducer element 362₂ axially displaceable with respect to the first element 361 in a first relative directional sense away from the local sleeve to displace the remote plug with respect to the remote sleeve to said wedged position by way of a further remote control rod 354

Operation thus comprises inserting each sleeve with its plug and associated locating LDT into its respective aperture, displacing the elements of the LDT to force the plugs into their wedged positions and lock the sleeves axially with respect to the apertures, and operating the actuation means to apply separating forces to axially force apart the sleeves and thus the apertured bodies. After the bodies have been forced apart, or such forcing relaxed to permits the bodies to return together, release means 325 permit removal of the apparatus.

Conveniently, the release means 25 is provided by the local and remote locating LDTs which are formed as double acting transducers and operable alternatively to displace the first and second transducer elements thereof axially, in a second relative directional sense towards the other sleeve, whereby each second transducer elements 362, and 362₂ are caused to displace each plug with respect to its respective sleeve out of the wedged position therein, permitting the local and remote parts to be separately removed from the body apertures.

As an alternative to the above described form, the local locating LDT may be a single acting transducer but the actuation LDT 50 may be double acting, as described above for apparatus 20, and the remote control rod abutment 340 may be arranged to bear upon the end of local sleeve 30 whereby upon operation of the actuation LDT to affect movement between the control rods in an opposite direction sense to actuation, reaction to the remote control rod abutment 340 bearing on sleeve 30 causes the local plug to be displaced from its wedged position.

It will be appreciated that in this embodiment the actuation means, and where appropriate part of the release means, may be formed between the plugs or in one of the plugs, as shown in schematic Figures 3(b) and 3(c) which correspond to Figures 2(b) and 2(c).

It will also be appreciated that like the first embodiment, this embodiment may also take a form 400, as illustrated in Figure 3(d), in which the local and remote plugs taper in a sense in which they narrow in cross-section towards each other.

Figure 3(d) also serves to illustrate that the form taken by any hydraulic piston and cylinder arranged may be other than the annular forms shown in Figures 3(a) to (c), where there is no requirement to coaxially surround control rods and the like, and may comprise a simple circular piston disposed with a circular cylinder body on the longitudinal axis of the sleeves.

As mentioned above it may be necessary to force apart flanged bodies in which the apertures are aligned but not in communication, and apparatus may take on form 500, as illustrated schematically in Figure 3(e) for use in such circumstances.

The sleeves 30 and 35 are as described for apparatus 300. The locating means and plug tapers may be as apparatus 300 or 400, and are illustrated only insofar as axial displacement creates radial expansion of each sleeve into frictional contact with its respective aperture. Actuation means 25, in the form of actuation LDT 550 is disposed radially offset from the apertures and the bodies containing them. The first transducer element 551 is rigidly coupled to the local sleeve 30, or possibly the local plug by way of the local locating LDT 560,, and the second transducer element 553 is coupled by abutment surface 540 to bear on the remote sleeve 35, or possibly remote plug by way of the remote locating LDT 560₂. Operation of the actuation means forces apart the body flanges to the extent necessary to remove and replace and intervening body.

Clearly, in all the forms described for this embodiment, if the aperture pairs are offset radially from the axis of a body, such as a pipe, and corresponding aperture pairs exist at other locations about that axis, corresponding apparatus may conveniently be disposed in such other apertures and operated simultaneously as in a multiplexed manner to effect substantially forcing apart of the bodies uniformly with respect to such axis. It will also be appreciated that the component parts of this second embodiment of apparatus, particularly the linear displacement transducers, may be formed by mechanical components instead of hydraulic components, as shown for example in Figure 3(f) in apparatus 600.

Each tapered plug 634, 639 has a control rod 652,, 652₂ respectively extending therefrom which has a threaded surface 662,, 662₂ adjacent the end of the sleeve and carries a correspondingly threaded flange 661 ,, 661₂. Each flange is able to be rotated relative to the control rod to bear on the flanged sleeve end to draw the plug into the sleeve and its wedged position thereby comprising with the threaded rod locating means. The local plug 634 and its (local) control rod 652, is hollow and supports a separate remote control rod 654 which terminates in an abutment surface 640 to bear on the remote plug. The local plug is internally threaded at 651 and the remote control rod 654 is correspondingly threaded at 653 such that rotation of the remote control rod applies axial separating force to the two parts. When the bodies are separated or otherwise finished with, the sleeves may be removed by rotating the flanges to clear the sleeves and impacting the control rods to dislodge the plugs from their wedged positions. Alternatively, further abutment surfaces 630 and 635 parallel, and fixed to, the sleeve flanges may be provided and the flanges rotated against these and/or the abutment surface 640 at the end of remote control rod 654 may be of such diameter as to overlie the end of local sleeve 30 such that counter rotation of the rod 654 within the local plug causes the latter to be displaced axially from its wedged position. If such flange rotation is impractical or requires excessive torque, the flanges may be provided with threaded through-apertures and jack screws (shown ghosted at 650') to bear on the sleeve flanges in the manner illustrated in Figure 2(d) to force the flanges away from the sleeve in locating the plugs to their wedged positions and to draw the flanges towards the sleeve to release the plugs from the wedged positions.

Such mechanical form of linear displacement transducers may, of course, be adapted to plugs tapering in either axial direction and/or employed in combination with fluid operated transducers.

Claims

. Apparatus for forcing apart a pair of bodies having aligned aperture therein, the apparatus being characterised by

(1 ) a local part having a local sleeve arranged to be disposed in one body in one of the aligned apertures, the local sleeve having a longitudinal axis extending along the aperture and an inner wall tapered over at least part of its axial length and containing a correspondingly tapered local plug,

(2) a remote part having a remote sleeve arranged to be disposed in the other body in the other of said aligned apertures in line with the local sleeve, the remote sleeve having a longitudinal axis extending along the aperture and an inner wall tapered over at least part of its axial length and containing a correspondingly tapered remote plug,

(3) locating means arranged to dispose said local and remote sleeves in fixed positional relationship with respect to each other in the relatively fixed bodies and move each plug within its respective sleeve to a wedged position at which the sleeve is expanded by the plug into frictional engagement with the aperture and the plug is wedged against further motion along the sleeve,

(4) actuation means operable to force the sleeves apart substantially along the line of the apertures to separate the bodies, and

(5) release means operable to move the local and remote plugs with respect to their sleeves out of said wedged positions to permit said sleeves to contract from said frictional engagement with the apertures and to permit each sleeve and its plug to be removed from the respective body aperture.

2. Apparatus as claimed in claim 1 characterised in that each of the local and remote sleeves is slit at at least one location about its periphery by at least one radial through aperture extending axially for at least part of the length of the sleeve.

3. Apparatus as claimed in claim 1 or claim 2 characterised in that the actuation means comprises an actuation linear displacement transducer (LDT) disposed in line with the plugs, having a first transducer element, operatively fixed in relation to one plug, and a second transducer element, axially displaceable with respect to the first element, coupled to the other part by control rod means.

4. Apparatus as claimed in claim 3 characterised in that the actuation LDT is disposed adjacent the end of the local sleeve remote from the remote sleeve, with said first transducer element operatively fixed to the local plug by local control rod means and said second transducer element coupled to said remote part by way of remote control rod means extending by way of through aperture means in the local plug.

5. Apparatus as claimed in claim 4 characterised in that the local control rod means comprises a tubular member and the remote control rod means comprises a single rod extending coaxially along the tubular member.

6. Apparatus as claimed in any one of the preceding claims characterised in that the local and remote plugs are tapered in an opposite sense to each other and narrowing in cross- sectional area in an axial direction away from each other and the actuation means is operable to force said sleeves apart by applying a separating force to said local and remote plugs.

7. Apparatus as claimed in any one of the preceding claims characterised in that the remote part is connected to said local part by way of the locating means such that both said parts are arranged to be disposed in, and removed from, said apertures by way of the aperture in said one body.

8. Apparatus as claimed in claim 7 characterised in that the locating means comprises a locating linear displacement transducer (LDT), disposed adjacent the end of the local sleeve, remote from the remote sleeve having a first transducer element arranged to bear against the local sleeve in an axial direction and a second transducer element, axially displaceable with respect to the first element, connected to the remote sleeve by way of tie means extending axially of the local sleeve.

9. Apparatus as claimed in claim 8 characterised in that the locating LDT is arranged to locate the remote sleeve axially relative to the local sleeve such that said second transducer element of the locating LDT is held displaced with respect to the first element thereof in a direction away from the remote sleeve by at least the displacement required for forcing apart the bodies and the locating means includes a further locating LDT, having a first transducer element operatively fixed in relation to one plug, and a second element, axially displaceable with respect to the first element, coupled to the other plug, said further locating LDT being operable to displace the plugs axially with respect to each other into their respective sleeves each into said wedged position.

10. Apparatus as claimed in claim 9 characterised in that the locating means includes locking means operable to be locked to prevent the transducer elements of the locating LDT from being displaced axially under force exerted between the plugs and sleeves by the further locating LDT in displacing said plugs to their wedged positions and to be unlocked to permit the elements of the locating LDT to be displaced axially, permitting separation of the wedged plugs and bodies, in response to forces exerted by the actuation means.

1 1. Apparatus as claimed in claim 0 when dependent on any one of claims 3 or 4 characterised in that said further locating LDT comprises said actuation LDT.

12. Apparatus as claimed in any one of claims 9 to 1 1 characterised in that the release means comprises a release linear displacement transducer (LDT) disposed in line with the plugs having a first transducer element, operatively fixed in relation to one plug, and a second transducer element, axially displaceable with respect to the first element, coupled to the other plug by control rod means, said release LDT being operable to displace the plugs with respect to each other such that each plug is displaced axially with respect to its respective sleeve from said wedged position, and in that one plug is arranged to be displaced from a wedged position in preference to the other and in a direction towards said other plug, said one plug including abutment means arranged upon said displacement to abut the sleeve containing said other plug such that the relative displacement force between the transducer elements acts between said other plug and its sleeve to displace the other plug from its wedged position.

13. Apparatus as claimed in claim 12 characterised in that the actuation LDT comprises a double acting transducer operable to displace the first and second transducer elements thereof in one relative directional sense to force the plugs apart and operable alternatively to displace said first and second elements in the opposite relative directional sense to force the plugs towards each other, and said release LDT comprises the actuation LDT.

14. Apparatus as claimed in any one of claims 1 to 6 characterised in that the remote part is separate from the local part, each sleeve, with its associated plug, being arranged to be disposed in and removed from its respective aperture by way of an aperture end remote from the other aperture.