WO2011138306A1

WO2011138306A1 - Radially expandable assembly and use thereof

Info

Publication number: WO2011138306A1
Application number: PCT/EP2011/057012
Authority: WO
Inventors: Cedric Terence Cooke
Original assignee: Cedric Terence Cooke
Priority date: 2010-05-04
Filing date: 2011-05-03
Publication date: 2011-11-10
Also published as: GB201007326D0; GB2477361A; GB2477361B

Abstract

A radially expandable assembly comprises a first elongate member (3, 27, 55, 83), a second elongate member (1, 29, 59, 93) movable in an axial direction relative to the first member, one of the first and second members being provided with a substantially conical surface (11, 41, 63), and a radially expandable and contractable component (17, 45, 67, 95). The radially expandable and contractable component comprises a plurality of part-cylindrical members (19, 47, 69, 97, 103) which together extend substantially in a circle and are provided with a resilient member (21, 21', 21", 49, 71, 99, 109) biasing the part-cylindrical members radially inwardly. Consequently, movement in a first direction of the member provided with the substantially conical surface (11, 41, 63) causes the surface to engage with a radially inner surface of the radially expandable component (17, 45, 67, 95) so as to move the part-cylindrical members (19, 47, 69, 97, 103) radially outwardly beyond a periphery of an outer of the first and second members and movement in a second direction causes the part-cylindrical members to contract radially inwardly under the biasing effect of the resilient member (21, 21', 21", 49, 71, 99, 109) such that the part-cylindrical members do not extend outwardly beyond the periphery of the outer of the first and second members.

Description

RADIALLY EXPANDABLE ASSEMBLY AND USE THEREOF

The present assembly relates to a radially expandable assembly and to the use thereof, for example as a blind fixing bolt and/or as a drill.

Blind fixing bolts are known, for example for fixing to hollow sections, tubes and regions where access is available from one side only.

Blind fixing bolts include bolts sold under the Registered Trade Mark “Hollo-Bolt” which comprises a metal sleeve arranged around the threaded portion of a bolt, the sleeve being provided with slits extending part of the length of the sleeve from the free end thereof. An internally threaded conical member is arranged on the end of the threaded portion of the bolt. In use, the bolt, including the sleeve and the conical member, is inserted into or through an aperture in a part to which the bolt is to be secured. The bolt is then rotated relative to the conical member (for example, as a result of friction between the conical member and the sleeve) which causes the conical member to move in the axial direction of the bolt and to be drawn into the sleeve. Such axial movement of the conical member into the sleeve causes the sleeve to deform and to expand so as to be retained in the part. A radially outwardly extending collar is provided at that end adjacent to the head of the bolt that is external of the part and a rubber washer may be provided between the collar and the sleeve. The disadvantages of such a bolt are that a large diameter hole is required to accommodate the sleeve and the conical member in addition to the shank of the bolt and that the bolt can only be used once. Moreover, where the bolt passes through more than one layer, it is not capable of pulling the layers together.

Another blind fixing bolt is known as the Mola Peg bolt and comprises a bolt member having a threaded portion with a hexagonal nut mounted thereon and a cylindrical portion formed with one or more slits extending from a free end thereof. An axial hole is formed through the bolt member and a cylindrical pin is provided in the axial hole, the pin extending axially outwardly of the bolt member for securing the bolt in place. The axial hole is profiled such that its radial dimension in the region of the free end of the cylindrical portion is less than in the threaded portion. In this way, when the bolt is inserted into a hole or aperture in a part, the free end of the pin can be struck with a hammer or other impact device to move the pin axially towards the cylindrical portion. Movement of the pin causes the cylindrical portion to expand radially and to prevent the bolt being removed from the part. The disadvantages of such a bolt is that the pin can fall out, reducing the tensile strength of the fastening and the bolt can only be used once.

A further blind fixing bolt is known as the Blind Bolt and comprises a bolt member having a threaded portion and a substantially cylindrical portion. The cylindrical portion is formed with an axially extending diametral slit within which an anchor is pivotably mounted. The head of the threaded portion is formed with a slot for receiving a screw driver so as to be able to rotate the bolt member and the bolt member is formed with an axially extending peripheral slot for the insertion of a tool for causing the anchor to pivot in order to be able to release the bolt. A hexagonal or other nut is threaded onto the bolt member and a collar is provided beneath the nut. The bolt is used by orienting the bolt member such that the anchor is not deployed and inserting the bolt member into a hole or aperture in a part and then twisting the bolt member so as to cause the anchor to deploy. The nut can then be tightened as required. The bolt can be removed by loosening the nut and twisting the bolt member such that the anchor is able to be retracted. A tool is then inserted along the axial slot in order to retract the anchor. Although the bolt can be removed and re-used, it has the disadvantage that it is essential to fit the bolt correctly otherwise the anchor will not deploy, or will not deploy fully. Moreover, the axial slot weakens the bolt member and the dimensions of the anchor are constrained such that the bolt is only able to withstand low loads.

It is therefore an object of the present invention to overcome, or at least ameliorate, the abovementioned disadvantages.

According to the present invention there is provided a radially expandable assembly comprising a first elongate member, a second elongate member movable in an axial direction relative to the first member, one of the first and second members being provided with a substantially conical surface, and a radially expandable and contractable component comprising a plurality of part-cylindrical members which together extend substantially in a circle and are provided with a resilient member biasing the part-cylindrical members radially inwardly, whereby movement in a first direction of the member provided with the substantially conical surface causes the surface to engage with a radially inner surface of the radially expandable component so as to move the part-cylindrical members radially outwardly beyond a periphery of an outer of the first and second members and movement in a second direction causes the part-cylindrical members to contract radially inwardly under the biasing effect of the resilient member such that the part-cylindrical members do not extend outwardly beyond the periphery of the outer of the first and second members.

The part-cylindrical members may be biased by a plurality of resilient members. The resilient member or members may be provided within the part-cylindrical members in the form of at least one compression spring or at least one tension spring. Alternatively, the resilient member or members may be provided within a circumferential recess provided in a radially outwardly facing surface of the part-cylindrical members. As a further alternative, the resilient member or members may be provided on a radially recessed region at one or each axial end of the part-cylindrical members. The part-cylindrical members may be provided with a radially inwardly extending portion engaging with a recess formed in one of the first and second members.

A radial member may be provided for guiding the part-cylindrical members. The radial member may comprise a radially inwardly extending portion provided on each of the part-cylindrical members, the radially inwardly extending portion engaging with a recess formed in one of the first and second members.

The substantially conical surface may be provided on a substantially cylindrical sleeve forming the first member threaded on to a substantially cylindrical threaded member forming the second member. The radially expandable and contractable component may be positioned between the conical surface of the cylindrical sleeve and an enlarged head of the second member. The cylindrical sleeve may be formed with a radially outwardly extending flange at an end thereof remote from the conical surface. The flange may be formed integrally with the remainder of the sleeve or may be formed as a separate component and secured to the remainder of the sleeve. Where the flange is formed as a separate component, it may be formed with a cylindrical recess for accommodating a part of the axial extent of the remainder of the sleeve. A nut or the like may be threaded onto the cylindrical threaded member for engaging with the flange. The end of the cylindrical threaded member may be provided with means, such as a pair of substantially parallel surfaces, for receiving means for rotating the threaded member.

As an alternative, the nut may be threaded onto the substantially cylindrical sleeve and an end of the sleeve remote from the conical surface may be provided with means, such as a pair of substantially parallel surfaces, for receiving means for rotating the sleeve.

In an alternative embodiment, the radially expandable and contractable component may be provided within an annular recess formed in a first member, the first member being formed with an axial bore within which the second member is axially movable relative to the first member, the second member being provided with the conical surface at an end thereof substantially within the first member. The second member may be axially movable by way of a threaded engagement with the first member. The part-cylindrical members may be provided with radially inwardly extending portions which extend through a recess formed in the first member and into the bore thereof for engagement with the conical surface of the second member. The first member may be externally threaded and a nut or the like may be threaded onto the first member. A washer may be provided on the first member between the nut and the radially expandable component. The second member may be provided at the end thereof remote from the conical surface with means for receiving means for rotating the second member. The first member may be provided with a smooth outer surface along part of the length thereof, for example in a region adjacent to the radially expandable component. In such a case, the washer may be provided with a cylindrical recess for accommodating part of the axial extent of the smooth outer surface of the first member.

According to another alternative, the radially expandable and contractable component may be provided within a recess formed in the first member, the first member being formed with an axial bore within which the second member is axially movable relative to the first member, the second member being provided with the conical surface at an end thereof substantially within the first member. The second member may be axially movable by way of threaded engagement with the first member. The part-cylindrical members may be provided with radially inwardly extending portions which extend through a recess formed in the first member and into the bore thereof for engagement with the conical surface of the second member. Alternatively, the part-cylindrical members may be hinged to the first member. A radially outer surface of the part-cylindrical members is provided with an abrasive material, such as diamond.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a longitudinal cross-sectional view of one embodiment of a radially expandable assembly according to the present invention in a first configuration;

Figure 2 is a longitudinal cross-sectional view of the radially expandable assembly of Figure 1 in a second configuration;

Figure 3 is an end view of the radially expandable assembly of Figures 1 and 2;

Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 1;

Figure 5 is a cross-sectional view corresponding to Figure 4 of the radially expandable assembly of Figure 2;

Figure 6 is a cross-sectional view of a modification of the embodiment of Figures 1 to 5;

Figure 7 is a longitudinal cross-sectional view of another embodiment of a radially expandable assembly according to the present invention in a first configuration;

Figure 8 is a longitudinal cross-sectional view of the radially expandable assembly of Figure 7 in a second configuration;

Figure 9 is an end view of the radially expandable assembly of Figures 7 and 8;

Figure 10 is a longitudinal cross-sectional view of a further embodiment of a radially expandable assembly according to the present invention in a first configuration;

Figure 11 is a longitudinal cross-sectional view of the radially expandable assembly of Figure 10 in a second configuration;

Figure 12 is an end view of the radially expandable assembly of Figures 10 and 11;

Figure 13 is a cross-sectional view taken along the line XIII-XIII in Figure 10;

Figure 14 is a cross-sectional view corresponding to Figure 13 of the radially expandable assembly of Figure 11;

Figure 15 is a cross-sectional view showing a modification of Figure 11;

Figure 16 is a cross-sectional view showing a modification of part of Figure 15;

Figure 17 is a cross-sectional view illustrating a modification of part of the radially expandable assembly according to the present invention;

Figure 18 is a cross-sectional view illustrating an alternative modification of part of the radially expandable assembly according to the present invention;

Figures 19, 20 and 21 are views of a further embodiment of a radially expandable assembly which can be used for cutting an annular recess; and

Figure 22 is a partial view showing a modification of the radially expandable assembly of Figures 19, 20 and 21.

The radially expandable assembly shown in Figures 1 to 5 comprises a bolt member 1 which is externally threaded to receive an operating member 3 and a hexagonal nut 5 or like threaded fastening member. The free end of the bolt member 1 is formed with a pair of flat surfaces 7 (Figure 3) for receiving a spanner or the like for controlling rotation of the bolt member. As an alternative to flat surfaces, the free end of the bolt member may be provided with a slot for receiving a screwdriver or with another recess for use with a complementary tool. The operating member 3 comprises a sleeve portion 9 provided with a conical portion 11 at that end remote from the flat surfaces 7 and with a radially extending flange 13 at that end adjacent to the flat surfaces. The flange 13 may be integral with the sleeve portion 9 or may be a separate component secured to the sleeve portion.

That end of the bolt member 1 opposite the flat surfaces 7 extends beyond the conical portion 11 of the operating member 3 and is formed with an enlarged head 15, the head having a greater radial dimension for example corresponding substantially to the diameter of the sleeve portion 9 of the operating member 3.

Arranged between the conical portion 11 and the head 15 is a radially expandable and contractable component 17 which comprises a plurality of part-cylindrical members 19, two being shown in the figures, which are retained around the shaft of the bolt member 1 and/or the conical portion 11 by a plurality of resilient members 21. As illustrated in Figures 1 to 5, the resilient members 21 are in the form of circumferential resilient members, but the resilient members may take other forms as will be explained hereinafter. Typically, the part-cylindrical members 19 in combination extend substantially in a circle. Each part-cylindrical member 19 is formed with a circumferential recess 23 with a circumferential flange 25 to each side of the recess. The resilient members 21 extend around the circumference of the combined part-cylindrical members 19 within the recess 23 between the flanges 25 so as to urge the part-cylindrical members radially inwardly against the surface of the bolt member 1 and/or the conical portion 11 and cause the part-cylindrical members to contract radially inwardly such that the part-cylindrical members do not extend outwardly beyond the periphery of the head 15 of the bolt member 1. The resilient members 21 may, for example, comprise one or more helically wound spring members which are in the form of a circle and/or one or more elastomeric members.

In use of the radially expandable assembly shown in Figures 1 to 5, the assembly is chosen to have a sufficient length such that the head 15 and part-cylindrical members 19 extend through a hole in one or more parts to which the assembly is to be secured. The bolt member 1 is rotated relative to the operating member 3 using the flat surfaces 7 and a suitable tool such as a spanner so as to move the head 15 away from the conical portion 11 and to allow the part-cylindrical members 19 to contract radially under the influence of the resilient members 21 to allow the head and the sleeve portion 9 of the operating member 3 to pass through the hole. This arrangement is shown in Figures 1 and 4.

When the radially expandable assembly has been inserted into the hole with the part-cylindrical members 19 and the head 15 emerging at the other side of the hole, the bolt member 1 is rotated relative to the operating member 3 again using the flat surfaces 7 and a suitable tool so as to draw the head 15 towards the conical portion 11. This causes the part-cylindrical members 19 to ride up onto the conical portion 11 which causes the part-cylindrical members to move radially outwardly as shown in Figures 2 and 5. Once this has been completed, the hexagonal nut 5 can be tightened to draw the head 15 towards the rear side of the hole such that the part-cylindrical members 19 bear on one side thereof against the rear side of the part or parts to which the assembly is to be secured and on the other side thereof against the head 15 of the bolt member 1. Where two or more parts are to be secured together the part-circumferential members 19 and the nut 5 draw the parts together.

Thus, the radially expandable assembly of the present invention, when in the form of an expandable bolt assembly, can be deployed in the manner described above. It can also be removed simply by reversing the steps, the resilient members 21 serving to cause the part-cylindrical members 19 to contract radially so as to allow the bolt assembly to be removed.

Such an expandable bolt assembly is primarily used for box-section parts, but can be used wherever access to the rear of the bolt assembly is not possible or at least not convenient. Such an expandable bolt assembly can also be used for fixing into concrete in which an undercut recess has been formed.

A further use of the radially expandable assembly is as part of a bearing puller. In this case the assembly is inserted into and partly through the bearing, with the nut 5 bearing against a support member which spans the bearing to be removed. The part-cylindrical members 19 are expanded radially so as to engage behind the bearing and the nut 5 is tightened to draw the bearing from its housing.

If desired, radial movement of the part-cylindrical members may be guided by providing the members with a radially inwardly extending pin, peg or plate which is received in a recess formed in the bolt member 1.

The radially expandable assembly shown in Figure 6 is similar to that shown in Figures 1 to 5 but is adapted to variable thicknesses in the parts to be secured. As shown in Figure 6, the flange 13 is formed with a recess to receive a part of the sleeve portion 9, so reducing the overall length of the operating member 3. To cater for variable thicknesses of the parts to be secured, as illustrated the flange 13 has been recessed. Alternatively, the axial length of the sleeve portion 9 can be reduced to a minimum and one or more spacers or a compression spring may be employed. Alternatively, the part-cylindrical members 19 may be drawn towards the parts to be secured, thus compensating for varying thicknesses. Either way, the flange 13 and the part-cylindrical members 19 can be drawn tightly against the parts to be secured.

The radially expandable assembly shown in Figures 7 to 9 comprises an outer bolt member 27 and an inner bolt member 29. The outer bolt member is externally threaded to receive a hexagonal nut 31 or like threaded fastening member and is internally threaded to receive the externally threaded inner bolt member 29. The free end of the outer bolt member 27 is formed with a pair of flat surfaces 33 for receiving a spanner or the like for controlling rotation of the outer bolt member and the free end of the inner bolt member 29 is formed with a pair of flat surfaces 35 for receiving a spanner or the like for controlling rotation of the inner bolt member. A washer 37 is provided adjacent to the nut 31.

That end of the outer bolt member 27 opposite the flat surfaces 33 is formed with a cylindrical shoulder 39 and a conical surface 41 extending in an axial direction away from the end formed with the flat surfaces 33.

That end of the inner bolt member 29 opposite the flat surfaces 35 extends beyond the conical surface 41 of the outer bolt member 27 and is formed with an enlarged head 43, the head having a greater radial dimension for example corresponding substantially to the diameter of the shoulder 39 of the outer bolt member 27.

Arranged between the conical surface 41 and the head 43 is a radially expandable and contractable component 45 which comprises a plurality of part-cylindrical members 47, two being shown in the figures which are retained around the shaft of the inner bolt member 29 and/or the conical surface 41 by one or more circumferential resilient members 49. Typically, the part-cylindrical members 47 in combination extend substantially in a circle. Each part-cylindrical member 47 is formed with a circumferential recess 51 with a circumferential flange 53 to each side of the recess. The resilient members 49 extend around the circumference of the combined part-cylindrical members 47 within the recess 51 between the flanges 53 so as to urge the part-cylindrical members radially inwardly against the surface of the bolt member 1 and/or the conical portion 11 and cause the part-cylindrical members to contract radially inwardly such that the part-cylindrical members do not extend outwardly beyond the periphery of the head 15 of the bolt member 1. The resilient members 49 may, for example, comprise one or more helically wound spring members which are in the form of a circle and/or one or more elastomeric members.

The radially expandable assembly of Figures 7 to 9 is used in substantially the same manner as that shown in Figures 1 to 5, but due to the outer larger threaded member 27 is self-adjusting for varying thicknesses of the parts to be secured.

Although the expandable member has been described in Figures 1 to 9 in relation to the

conical surface

11, 41 being provided on the sleeve portion 9 or bolt member 27, it is equally possible to provide the conical surface on the bolt member 7, 29 adjacent to the enlarged head 15, 43 (but facing in the opposite direction) and to draw the conical surface between the part-

cylindrical members

19, 47 instead of drawing the part-cylindrical members onto the conical surface.

The radially expandable assembly shown in Figures 10 to 14 comprises a bolt member 55 which is externally threaded to receive a hexagonal nut 57 or like threaded fastening member and which is internally threaded to receive an operating member 59. The free end of the bolt member 55 is formed with a pair of flat surfaces 61 (Figure 12) for receiving a spanner or the like for controlling rotation of the bolt member. The operating member 59 is provided at the free end thereof with a profiled, for example hexagonal, recess for receiving a tool for controlling rotation of the operating member relative to the bolt member 55. The other end of the operating member 59, within the bolt member, is formed with a conical surface 63. A washer 65 is provided on the bolt member adjacent to the hexagonal nut 57.

A circumferential recess is provided adjacent to that end of the bolt member 55 opposite the flat surfaces 61 and arranged within the circumferential recess is a radially expandable and contractable component 67 which comprises a plurality of part-cylindrical members 69, two being shown in the figures, which are retained around the shaft of the bolt member 55 within the circumferential recess by a plurality of circumferential resilient members 71. Typically, the part-cylindrical members 69 in combination extend substantially in a circle. Each part-cylindrical member 69 is formed with a circumferential recess 73 with a circumferential flange 75 to each side of the recess. The resilient members 71 extend around the circumference of the combined part-cylindrical members 69 within the recess 73 between the flanges 75 so as to urge the part-cylindrical members radially inwardly against the surface of the bolt member 55 and cause the part-cylindrical members to contract radially inwardly such that the part-cylindrical members do not extend outwardly beyond the periphery of the head of the bolt member 55. The resilient members 71 may, for example, comprise one or more helically wound spring members which are in the form of a circle and/or one or more elastomeric members.

As shown in Figures 12 and 13, radial movement of the part-cylindrical members 69 is guided by providing each member 69 with a radially inwardly extending pin 77 (or peg or plate) which is received in a recess formed in the bolt member 55.

In use of the radially expandable assembly shown in Figures 10 to 14, the assembly is chosen to have a sufficient length such that the part-cylindrical members 69 extend through a hole in one or more parts to which the assembly is to be secured. The operating member 59 is rotated relative to the bolt member 55 using the flat surfaces 61, the recess in the end of the operating member and suitable tools so as to move the conical surface 63 of the operating member 59 away from the radially expandable and contractable component 67 and to allow the part-cylindrical members 69 to contract radially under the influence of the resilient members 71 to allow radially expandable assembly to pass through the hole. This arrangement is shown in Figures 10 and 13.

When the radially expandable assembly has been inserted into the hole with the part-cylindrical members 69 emerging at the other side of the hole, the operating member 59 is rotated relative to the bolt member 55 again using the flat surfaces 61 and the recess in the end of the operating member together with suitable tools so as to move the conical surface 63 at the end of the operating member 59 between the part-cylindrical members 69. The operating member 59 has a greater diameter than the internal diameter of the part-cylindrical members 69 and therefore causes the part-cylindrical members 69 to ride up the conical surface 63 and onto the shaft of the operating member 59 which causes the part-cylindrical members to move radially outwardly as shown in Figures 11 and 14. Once this has been completed, the hexagonal nut 57 can be tightened to draw the part-cylindrical members 69 towards the rear side of the hole such that the part-cylindrical members 69 bear on one side thereof against the rear side of the part or parts to which the assembly is to be secured and on the other side thereof against the recess formed in the bolt member 55. Where two or more parts are to be secured together the part-circumferential members 69 and the hexagonal nut 57 draw the parts together.

Figure 15 is similar to Figure 11 except that the shank of the bolt member 55 is formed with a smooth surface 79 in a region adjacent to the radially expandable component 67. Figure 16 is a modification of Figure 15 for the situation in which the axial length of the smooth surface 79 exceeds the thickness of the part or parts through which the radially expandable assembly passes. In this case, the washer 65 is formed with a cylindrical recess 81 to accommodate an end portion of the smooth surface 79. Alternatively, the smooth surface 79 region of the bolt member 55 can be reduced in length and adjustment for varying thicknesses of the parts to be secured can be achieved by providing one or more spacers or a compression spring.

Although the expandable and contractable member has been described in Figures 10 to 16 in relation to the conical surface 63 being provided on the operating member 59 such that the conical surface is pushed between the part-cylindrical members 69, it is equally possible to provide the conical surface on the operating member facing in the opposite direction as an expanding cone rather than a contracting cone and to draw the conical surface between the part-cylindrical members 69 instead of drawing the part-cylindrical members onto the conical surface.

In the embodiments of Figures 10 to 16, that part of the bolt member 55 that passes through the parts to be secured need not be cylindrical, but could be, for example, square or hexagonal or any other convenient configuration to key with holes of complementary configuration formed through the parts to be secured.

Figure 17 shows a modification in which the circumferential resilient members have been replaced by resilient members in the form of compression springs 21’. The part-cylindrical members 19 have been modified such that they partially overlap and compress the springs 21’ as the members 19 expand. The springs then expand as they urge the part-cylindrical members back towards a contracted configuration.

Figure 18 shows a modification in which the circumferential resilient members have been replaced by resilient members in the form of tension springs 21”. As the part-cylindrical members 19 expand the springs 21" are stretched and the tension in the springs increases. The springs 21” then contract as they draw the part-cylindrical members back towards a contracted configuration.

Figures 19 to 21 show an embodiment of a radially expandable assembly which is adapted for cutting an annular recess in a bore. The bore can be formed in a layer of concrete or like material into which a bolt incorporating a radially expandable assembly is to be secured. Such a bolt may be in the form described herein. It is a straightforward matter to form a cylindrical bore, but significantly more difficult to form an annular recess which is capable of anchoring a bolt having a radially expandable assembly.

The radially expandable assembly shown in Figures 19 to 21 comprises a cylindrical member 83 which is formed with a reduced diameter portion 85 at a free end thereof for engaging with a drill chuck (shown in dashed lines) or the like. The reduced diameter portion need not be cylindrical and may have any suitable cross section for engaging the drill chuck. That end of the cylindrical member opposite the reduced diameter portion 85 is formed with an annular recess 87, with a flange 89 consequently being provided at the end of the cylindrical member 83. A cylindrical bore 91 is formed along the entire length of the axis of the cylindrical member 83 and an operating pin 93 having a conical end is slidably mounted in the bore 91 for axial movement.

Arranged within the annular recess 87 is a radially expandable and contractable component 95 which comprises a plurality of part-cylindrical members 97, two being shown in the figures, which are retained within the recess 87 by a plurality of circumferential resilient members 99 which are positioned within regions of reduced diameter placed either side of a central region of full diameter. Typically, the part-cylindrical members 97 in combination extend substantially in a circle. Each part-cylindrical member 97 is formed with a radially inwardly extending element 101, such as a pin, peg or plate, which engages in a radial bore formed in the cylindrical member 83 within the region of the annular recess 87, the element 101 extending into the cylindrical bore 91. Consequently, as the operating pin 93 is moved axially towards the elements 101, the elements 101 and therefore the part-cylindrical members 97 are moved radially outwardly by the conical end surface of the pin 93 against the biasing force of the resilient members 99, and as the operating pin 93 is moved axially away from the elements 101, the elements 101 and therefore the part-cylindrical members 97 are able to move radially inwardly under the biasing force of the resilient members 99. All or part of the radially outer surfaces of the part-cylindrical members 97 are formed of, coated with, or otherwise incorporate a hard material, for example, provided with a diamond or tungsten carbide coating, so as to abrade or cut the internal surface of a bore within which the radially expandable assembly is positioned in order to form an undercut region, the maximum depth of the undercut region being determined by the radius of the operating pin 93. The reduced diameter portions of the part-cylindrical members 97 ensure that the resilient members 99 do not protrude radially beyond the diameter of the cylindrical member 83 and are therefore not damaged by the wall of the bore in which the undercut region is being formed.

Figure 22 shows a modification of the radially expandable assembly of Figures 19, 20 and 21 in which the part-cylindrical members 103 are pivotally mounted to the cylindrical member 83 at one axial end 105 of the part-cylindrical members and are formed with a curved or otherwise profiled surface 107 which engages with the conical end of operating pin 93 so as to cause the part-cylindrical members to pivot and to urge the free ends thereof radially outwardly. A resilient member in the form of a tension spring 109 draws the part-cylindrical members 103 radially inwardly when the operating pin 93 is withdrawn.

Claims

A radially expandable assembly comprising a first elongate member (3, 27, 55, 83), a second elongate member (1, 29, 59, 93) movable in an axial direction relative to the first member, one of the first and second members being provided with a substantially conical surface (11, 41, 63), and a radially expandable and contractable component (17, 45, 67, 95) comprising a plurality of part-cylindrical members (19, 47, 69, 97, 103) which together extend substantially in a circle and are provided with a resilient member (21, 21’, 21”, 49, 71, 99, 109) biasing the part-cylindrical members radially inwardly, whereby movement in a first direction of the member provided with the substantially conical surface (11, 41, 63) causes the surface to engage with a radially inner surface of the radially expandable component (17, 45, 67, 95) so as to move the part-cylindrical members (19, 47, 69, 97, 103) radially outwardly beyond a periphery of an outer of the first and second members and movement in a second direction causes the part-cylindrical members to contract radially inwardly under the biasing effect of the resilient member (21, 21’, 21”, 49, 71, 99, 109) such that the part-cylindrical members do not extend outwardly beyond the periphery of the outer of the first and second members.
An assembly as claimed in claim 1, wherein the part-cylindrical members (19, 47, 69, 97, 103) are biased by a plurality of resilient members (21, 21’, 21”, 49, 71, 99, 109).
An assembly as claimed in claim 1 or 2, wherein the resilient member or members (21, 49, 71, 99, 109) is or are provided within the part-cylindrical members (19, 47, 69, 97, 103) in the form of at least one compression spring (21’).
An assembly as claimed in claim 1 or 2, wherein the resilient member or members (21, 49, 71, 99, 109) is or are provided within the part-cylindrical members (19, 47, 69, 97, 103) in the form of at least one tension spring (21”).
An assembly as claimed in claim 1 or 2, wherein the resilient member or members (21, 49, 71, 99) is or are provided within a circumferential recess (23, 51, 73) provided in a radially outwardly facing surface of the part-cylindrical members (19, 47, 69, 97).
An assembly as claimed in claim 1 or 2, wherein the resilient member or members (21, 21’, 21”, 49, 71, 99, 109) is or are provided on a radially recessed region at one or each axial end of the part-cylindrical members (19, 47, 69, 97).
An assembly as claimed in any preceding claim, wherein a radial member (77, 101) is provided for guiding the part-cylindrical members (19, 47, 69, 97).
An assembly as claimed in claim 7, wherein the radial member (77, 101) comprises a radially inwardly extending portion provided on each of the part-cylindrical members (19, 47, 69, 97), the radially inwardly extending portion engaging with a recess formed in one of the first and second members (1, 3, 27, 29, 55, 59, 83, 93).
An assembly as claimed in any preceding claim, wherein the substantially conical surface (11, 41, 63) is provided on a substantially cylindrical sleeve (9, 27) forming the first member (3) threaded on to a substantially cylindrical threaded member forming the second member (1, 29).
An assembly as claimed in claim 9, wherein the radially expandable and contractable component (17, 45) is positioned between the conical surface (11, 41) of the cylindrical sleeve (9, 27) and an enlarged head (15, 43) of the second member (1, 29).
An assembly as claimed in claim 9 or 10, wherein the cylindrical sleeve (9) is formed with a radially outwardly extending flange (13) at an end thereof remote from the conical surface (11).
An assembly as claimed in claim 11, wherein the flange (13) is formed integrally with the remainder of the sleeve (9).
An assembly as claimed in claim 11, wherein the flange (13) is formed as a separate component and secured to the remainder of the sleeve (9).
An assembly as claimed in claim 13, wherein the flange (13) is formed with a cylindrical recess for accommodating a part of the axial extent of the remainder of the sleeve (9).
An assembly as claimed in any one of claims 11 to 14, wherein a nut is threaded onto the cylindrical threaded member (1) for engaging with the flange (13).
An assembly as claimed in any one of claims 9 to 15, wherein the end of the cylindrical threaded member (1, 29) is provided with means (7, 35) for receiving means for rotating the threaded member.
An assembly as claimed in claim 16, wherein the end of the cylindrical threaded member (1, 29) is provided with a pair of substantially parallel surfaces (7, 35) for receiving means for rotating the threaded member.
An assembly as claimed in any one of claims 8 to 14, wherein a nut (31) is threaded onto the substantially cylindrical sleeve (9, 27) and an end of the sleeve remote from the conical surface (11, 41) is provided with means (33) for receiving means for rotating the sleeve.
An assembly as claimed in claim 18, wherein the receiving means comprises a pair of substantially parallel surfaces (33).
An assembly as claimed in any one of claims 1 to 8, wherein the radially expandable and contractable component (67) is provided within an annular recess formed in the first member (55), the first member being formed with an axial bore within which the second member (59) is axially movable relative to the first member, the second member being provided with the conical surface (63) at an end thereof substantially within the first member.
An assembly as claimed in claim 20, wherein the second member (59) is axially movable by way of threaded engagement with the first member (55).
An assembly as claimed in claim 20 or 21, wherein the part-cylindrical members (69) are provided with radially inwardly extending portions (77) which extend through a recess formed in the first member (55) and into the bore thereof for engagement with the conical surface (63) of the second member (59).
An assembly as claimed in claim 20, 21 or 22, wherein the first member (55) is externally threaded and a nut (57) is threaded onto the first member.
An assembly as claimed in claim 23, wherein a washer (65) is provided on the first member (55) between the nut (57) and the radially expandable component (67).
An assembly as claimed in any one of claims 20 to 24, wherein the second member (59) is provided at the end thereof remote from the conical surface (63) with means for receiving means for rotating the second member.
An assembly as claimed in any one of claims 20 to 25, wherein the first member (55) is provided with a smooth outer surface (79) along part of the length thereof.
An assembly as claimed in claim 26, wherein the first member (55) is provided with the smooth outer surface (79) in a region adjacent to the radially expandable component (67).
An assembly as claimed in claim 26 or 27 when dependent on claim 24 or any claim dependent thereon, wherein the washer (65) is provided with a cylindrical recess for accommodating part of the axial extent of the smooth outer surface (79) of the first member (55).
An assembly as claimed in any one of claims 1 to 8, wherein the radially expandable and contractable component (95) is provided within a recess formed in the first member (83), the first member being formed with an axial bore (91) within which the second member (93) is axially movable relative to the first member, the second member being provided with the conical surface at an end thereof substantially within the first member.
An assembly as claimed in claim 29, wherein the second member (93) is axially movable by way of threaded engagement with the first member (83).
An assembly as claimed in claim 29 or 30, wherein the part-cylindrical members (97) are provided with radially inwardly extending portions (101) which extend through a recess formed in the first member (83) and into the bore thereof for engagement with the conical surface of the second member (93).
An assembly as claimed in claim 29 or 30, wherein the part-cylindrical members (103) are hinged to the first member (83).
An assembly as claimed in any one of claims 29 to 32, wherein a radially outer surface of the part-cylindrical members (97, 103) is provided with an abrasive material.
An assembly as claimed in claim 33, wherein the abrasive material is diamond.