CA2197339C

CA2197339C - A gripping device

Info

Publication number: CA2197339C
Application number: CA002197339A
Authority: CA
Inventors: Ian Alistair Kirk
Original assignee: Downhole Products Ltd
Current assignee: Downhole Products Ltd
Priority date: 1994-08-12
Filing date: 1995-08-10
Publication date: 2006-10-24
Anticipated expiration: 2015-08-10
Also published as: CA2197339A1

Abstract

A gripping device (10) is described which has an inner member (14) and an outer member (12). The inner member has a split (20) which define a first end (b) and a second end (8). A selectively operable device (18) is also included to keep the first and second ends (6, 8) apart to permit the device (10) to be placed around an object (30) and to permit the first and second ends (6, 8) to move towards each other so that the inner member (14) grips the object (30). At least part of an outer face (26) of the inner member (14) interfits with at least a part of an inner face (22) of the outer member (12) in a manner such that when a load is applied to the outer member (12), the inner face (22) of the outer member (12) acts upon the inner member (14) to cause compression of the inner member (14) thereby increasing the grip of the inner member (14) on the object (30). The device (10) is then locked in position on the objet (30) and when the load is removed the action of the outer member (12) on the inner member (14) is reduced thereby decreasing the grip of the inner member (14) on the object (30) and unlocking the device (10) from the object (30).

Description

1.
1 "A Gripping Device"

2 This invention relates to a gripping device.

3 Clamping devices have been used to secure other devices to 4 pipes or tubes. As an alternative to this a ring with screws has also been used. However, the screws of these 6 rings can damage the pipe or tube to which the device is 7 attached. These clamping or ring devices ha~~re a particular 8 application in the oil industry for ~::7ilwell tubes and drill 9 pipes.
According to the present invention there is provided a 11 gripping device having an inner anc~ an outer member, the 12 inner member having a split defining a first and a second 13 end which can move towards one another so that the inner 14 member can grip an object, and in which at least a part of an outer face of the inner member inter.fits with at least a 16 part of an inner face of the outer member in a manner that 17 when a load is applied to the outer member the inner face of 18 the outer member acts upon the inner member to cause 19 compression of the inner member thereby increasing the grip of the inner member on the c.>bject and locking the device in 21 position on the object, and when the load is removed the 22 action of the outer member on the inner member is reduced 23 thereby decreasing the grip of the inner member on the 24 object and unlocking the device on tine object. The gripping device is further characterized by a selectively operable 26 device to keep the first and second ends apart to allow the 27 device to be placed round an object and to allow the first 28 and second ends to move together to drip the object.
29 Preferably, the inner member is a split :ring biased so that the ends of the split ring tend towards one another.

1 Preferably the selectively operable device is a wedging 2 device.
3 Preferably, a screw within a screw the wedging device is 4 thread, the screw thread being in transverse disposition within the slit. The screw may accessed .from an outer be 6 face the outer member to allow the screw to be removed of or 7 placed in the device.

8 Alternatively, the selectively operable device may be a 9 fastening means such as a jubilee type-clip positioned around the inner member.
11 Typically, the device may further include an initiation 12 device which biases the inner face of the inner member 13 against the object to help initiate the grip of the device 14 on the object. The initiation device may be provided by a spring loaded clip which at least partially encircles the 16 outer face of the inner member. In another embodiment, the 17 initiation device may be provided a locking mechanism, such 18 as a cable tie, which encircles the outer face of the inner 19 member and may be tightened to initiate the gripping of the 2 0 devi ce . --~----.--.-....-----.------.......-~.---..-.,----.

WO 96!Q5439 ~ ~ ~ ~A J ~ ~ PCTIGB95l01890 1 in a further alternative embodiment the selectively 2 operable device may be cooperating eccentric formations 3 on the inside of the outer member and the outside of 4 the inner member which cooperate with each other typically, when the outer member is rotated relative to 6 the inner member.
7 In one example of the invention the device may be in 8 the form of a ring which is slid over the object.

Preferably, the inner member is a single part.
11 Alternatively, the inner member may be in two or more 12 parts, to allow the inner member to be placed around 13 the object. The outer member may also be in two or 14 more parts to allow the outer member to be placed round the object with the inner member. The two or more 16 parts may be connected by any suitable means such as 17 pins and/or may be hinged.
18 Preferably, the outer face of the inner member has at 19 least one taper interfitting with an accommodating recess in the inner face of the outer member. This 21 arrangement may allow locking of the device on the 22 object in the direction of the applied load.
23 Alternatively, this arrangement may be such that the 24 device is lockable to the object in one direction and is moveable in an opposite direction.
26 Preferably, the outer member is a ring shape.
27 Preferably, the object is a pipe or tube.
28 Preferably, an inner face of the inner member has a 29 friction surface facilitating the gripping action when the wedging means is removed.

W096d05439 PCTIGB95101890 1 y ~.~5'y 1 Preferably, the outer face of the outer member is 2 suitably formed to permit flow of any material past the 3 device. This may be by providing flutes or spirals in 4 the outer face of the outer member.
Examples of a gripping device in accordance with the , 6 invention will now be described with reference to the 7 accompanying drawings, in which:
8 Fig. 1 is a plan view of a first example of a 9 gripping device;
Fig. 2. is an end view of an outer member of the 11 gripping device of Fig. 1;
12 Fig. 3 is a section through an inner member of the 13 device shown in Figs. 1 and 2;
14 Fig. 4 shows an example, in use, of the device shown in Fig. 1;
16 Fig. 5 shows a second example of a gripping 17 device;
18 Fig. 6 is a cross-sectional view through a third 19 example of a gripping device.
Figs. 1 to 4 show a gripping device generally indicated 21 by reference 10 which has an outer member 12 and an 22 inner member 14.
23 The outer member 12 is of a ring shape and has a recess 24 22 formed within the inner face of the outer member 12.
The recess 22 has inwardly sloping side walls. A screw 26 thread 16 is provided on an outer face 24 of the outer 27 member 12. The screw thread 16 provides an opening for 28 a screw 18 (Fig. 3) to be placed within the outer face 29 of the outer member 12.
The inner member 14 is a split ring with ends 6 and 8 31 and fits Within the outer member 12. The inner member W0 96Ip5439 ~ ~ ~ PCTIGB95I0189p 1 14 has a double tapered outer face 26 and this allows 2 the outer face 26 to interfit within the recess 22 of 3 the outer member 12. A screw thread 17 is provided 4 within the split 20 of the inner member 14 and the 5 screw thread 17 is disposed transversely within the 6 split 20.

7 When the inner member 14 is placed within the outer 8 member 12, the screw thread 17 of the inner member 14 9 is aligned with the screw thread 16 of the outer member 12. The screw 18 is then placed within the device 10 11 through the screw threads 16 and 17. In this position 12 the screw 18 acts as a wedge to keep the ends 6 and 8 13 of the inner member 14 apart. This enables the device 14 10 to be placed round an object such as a pipe or tube and when the device 10 is in a desired position on the 16 pipe or tube the screw 18 is removed to allow the ends 17 6 and 8 of the inner member 14 to move towards one 18 another to cause the inner member 14 to grip the pipe 19 or tube so that the device 10 remains in the desired position on the pipe or tube.
21 When a load is applied to an upper or lower edge of the 22 outer member 12 the shape of the recess 22 causes the 23 outer member 12 to partially move over the tapered 24 outer face 26 of the inner member 14 thereby compressing the inner member against the pipe or tube 26 by causing the ends 6 and 8 of the inner member 14 to 27 move further towards one another. Further movement of 28 the outer member 12 is prevented due to the shape of 29 the recess 22 and the interfitting outer face 26 of the inner member 14 causing compression of the inner member 31 14 against the pipe or tube. This causes the device 10 3Z to lock in position on the pipe or tube.
33 When the load is removed the compression of the inner ' CA 02197339 2006-03-30 1 member 14 against the pipe or tube is reduced so that the inner member 14 grips the pipe or 2 tube but the device 10 is not locked in position on the pipe or tube.

4 The device 10 may be used as shown in Fig. 4 where a load 28 is held in position on a pipe 30 between two gripping devices 32 and 34 each of the type described above.
Any upward 6 or downward force applied to the device 32 or 34 locks the device 32 or 34 in position on ? the pipe and the load 28 remains in position on the pipe.

9 An alternative embodiment is shown in Fig. 5 where a gripping device 40 has a split ring inner member 42 and a ring shape outer member 44. The outer face 41 of the inner member 11 42 has a single taper cooperating with an inner face 46 of the outer member 44. This 12 arrangement allows the device 40 to be locked in position on the pipe 48 when a load is 13 applied in one direction only, in this embodiment the device 40 is locked in position when a 14 load is applied to a lower edge 49 of the outer member 44 (ie when an upward face is applied).

1? Fig. 6 shows a third example of a gripping device 50 in use. The gripping device 50 18 comprises an outer member 51, an inner member 52 and a spring clip 53 located in a recess 19 54 in the radially outer surface of the spring clip 53. As shown in Fig. 6, the device 50 is mounted on the outside of a tubular pipe 55. The device 50 operates in a similar manner to 21 the device 10 shown in Figs 1 to 4.

23 However, the device 50 also includes a spring clip 53 which biases inner surface 56 of the 24 ~~.,~.,~~. ~.~.~~~.~.l.o.. c~ :,.,t.. ......f....E ...:a, .t... ....a..:a..
,.....r ..._ ..rat.. ~_t__~__ WO 96105439 ~ ~ ~ lr ~ ~ ~ PCTIGB95101890 1 55. This biasing action helps to increase the initial 2 gripping force of the inner member 52 on the tubular 55 3 and helps to initiate the gripping action of the device 4 50 so that when a force in the direction of either of arrows 57 or 58 is applied to the outer member 51 of 6 the device 50 movement of inner ring 52 in the 7 corresponding direction of the arrows 57, 58 is 8 minimised or prevented by the biasing action of the 9 spring clip 53 forcing the inner surface 56 within the inner member 52 against the surface of the tubular 55 11 and the tapered faces of the inner and outer members 12 cooperating to force the inner member to grip the 13 tubular 55. This initial gripping action may be 14 further improved by the provision of a friction coating on the surface 56.

16 The advantages of a gripping device according to the 17 invention are that no screws contact the object itself, 18 thereby reducing possible damage to the object. The 19 gripping device can be selected to allow movement of a device held between at least two gripping devices when 21 a force is applied in one direction or to allow no 22 movement of the device due to the locking of the 23 gripping and locking device in both directions of the 24 applied force.
Modifications and improvements may be incorporated 26 without departing from the scope of the invention.

Claims

WE CLAIM:

1. A gripping device having an inner and an outer member, the inner member having a split defining a first and a second end which can move towards one another so that the inner member can grip an object, and in which at least a part of an outer face of the inner member interfits with at least a part of an inner face of true outer member in a manner that when a load is applied to the outer member the inner face of the outer member acts upon the inner member to cause compression of the inner member thereby increasing the grip of the inner member on the object and locking the device in position on the object, and when the load is removed the action of the outer member on the inner member is reduced thereby decreasing the grip of the inner member on the object and unlocking the device on the object, characterised by a selectively operable device to keep said first and second ends apart to allow the device to be placed round an object and to allow the first and second ends to move together to grip the object.

2. A gripping device according to claim 1, wherein the inner member is a split ring biased so that the ends of the split ring are biased towards each other.

3. A gripping device according to claim 1 or claim 2, wherein the selectively operable device comprises a wedging device.

4. A gripping device according to claim 3, wherein the wedging device comprises a screw threaded member.

5. A gripping device according to any one of claims 1 to 4, wherein the device further includes an initiation device to bias the inner face of the inner member against the object to help initiate gripping of the device on the object.

6. A gripping device according to claim 5, wherein the initiation device comprises a spring loaded clip which at least partially encircles the outer face of the inner member.

7. A gripping device according to any one of claims 1 to 6, wherein a friction coating is provided on the inner face of the inner member.

8. A gripping device according to any one of claims 1 to 7, wherein the inner member has a tapered portion on the outer face which co-operates with a corresponding tapered portion on the inner face of the outer member.

9. A gripping device according to any one of claims 1 to 8, wherein the outer face of the inner member has two tapered portions which taper in opposite directions and cooperate with corresponding tapered portions on the inner face of the outer member.

10. A gripping device according to any one of claims 1 to 9, wherein at least a portion of the selectively operable device can be disposed between the first and second ends of the inner member.

11. A gripping device according to any one of claims 1 to 10, wherein the selectively operable device is actuable between a first configuration in which a spacer is located between the ends of the inner member, and a second configuration in which the spacer is removed from between the ends of the inner member.