Lucas, Brian Ronald
| 1. | A tong having at least one active jaw holder (24) and at least one passive jaw holder (10), characterized in that said passive jaw holder (10) can be moved to different positions to accommodate pipes (20) of differ¬ ing diameters. |
| 2. | A tong as claimed in Claim 1, characterized in that said passive jaw holder (10) is connected to a drive member (13) in a manner such that rotation of said drive member in one sense urges said jaw holder in one direc¬ tion whilst rotation of said drive member in the oppo¬ site sense urges said jaw holder in the opposite direc¬ tion. |
| 3. | A tong as claimed in Claim 2, characterized in that said drive member (13) comprises a threaded shaft (13) and said passive jaw holder (10) is provided with an internally threaded bore (12) which engages said thread¬ ed shaft (13). |
| 4. | A tong as claimed in Claim 1, 2 or 3, wherein said tong is a power tong (1) having a housing (2) and a rotary (3) rotatably mounted therein. |
| 5. | A power tong as claimed in Claim 4, when appended to Claim 2 or 3, wherein the drive member (13) is ar¬ ranged to act between the rotary (3) and the jaw holder (10). |
| 6. | A power tong as claimed in Claim 4 or 5, wherein including an actuator (16, 18) mounted on said housing (2) and actuable to advance a member (17) into engage¬ ment with the drive member (13) and to rotate the same until the jaw holder (10) is in the desired position. |
| 7. | A power tong as claimed in Claim 6, including a sensor to inhibit actuation of said actuator (16, 18) when not aligned with said drive member (13). |
| 8. | A power tong as claimed in Claim 6 or 7, including a sensor to inhibit rotation of said drive member (13) until drivingly engaged with said actuator (16, 18). |
| 9. | A power tong as claimed in Claim 6, wherein said actuator (16, 18) is connected to a computer and is responsive to signals therefrom. |
| 10. | A tong as claimed in Claim 1, 2 or 3, or a power tong as claimed in any one of Claims 4 to 9, including two or more passive jaw holders each of which can be moved to different positions to accommodate pipes of differing diameters. |
| 11. | A tong as claimed in Claim 1, 2, 3 or 10, or a power tong as claimed in any one of Claims 4 to 9 or 10, wherein at least one (10') of said active jaw holder (24) and said passive jaw holder (10) includes a stud (30) which projects outwardly from said jaw holder (10*) and is provided with a bore (31) lined with a sleeve (32) of resilient material, and a jaw (7') is provided which is mounted on said jaw holder (10') by a member (34) which extends through said jaw (7' ) and said resilient sleeve (32). |
Tongs are used in the drilling industry for grip¬ ping and rotating pipes. Generally, the pipes are gripped between one or more passive jaws and one or more active jaws which can be urged against the pipe.
Normally, the radial position of the passive jaw(s) is fixed and consequently these jaws and/or their jaw holders must be changed to accommodate pipes of differ- ent diameters.
According to the present invention there is provid¬ ed a tong having at least one active jaw holder and at least one passive jaw holder, characterized in that said passive jaw holder can be moved to different positions to accommodate pipes of differing diameters.
Preferably, said passive jaw holder is connected to a drive member in a manner such that rotation of said drive member in one sense urges said jaw holder in one direction whilst rotation of said drive member in the opposite sense urges said jaw holder in the opposite direction.
Advantageously, said drive member comprises a threaded shaft, and said passive jaw holder is provided with an internally threaded bore which engages said threaded shaft.
The tong may be a back-up tong, which is simply used for holding a pipe stationary, or a power tong, which is used for rotating the pipe.
When the tong is a power tong having a housing and a rotary rotatably mounted therein, the jaw holder is preferably mounted in the rotary and the threaded shaft is arranged to act between the rotary and the jaw hold¬ er.
In such an embodiment the threaded shaft may be rotated by, for example a screwdriver or a socket driv-
er. In a preferred embodiment an actuator is mounted on the housing and, when actuated, advances a member into engagement with the drive member and rotates the same until the jaw holder is in the desired position. The member is subsequently retracted to allow the rotary to rotate with respect to the housing.
If desired, a sensor may be provided to inhibit actuation of said actuator when not aligned with said drive member. A sensor may also be provided to inhibit rotation of said drive member until drivingly engaged with said actuator.
Normally, two or more passive jaw holders will be present each of which will preferably be adjustable by its own actuator.
Preferably, the or each actuator is computer con¬ trolled so that when the diameter of a pipe to be gripped is entered into the computer the passive jaw(s) are advanced to the desired position. Once the passive jaw(s) are in position the pipe is pressed against them by advancing one or more active jaw(s) against the pipe. This can be achieved mechani¬ cally or hydraulically as described and claimed in our co-pending application No of even date.
Advantageously, at least one of said active j aw holder and said passive jaw holder includes a stud which projects outwardly from said jaw holder and is provided with a bore lined with a sleeve of resilient material, and a j aw is provided which is mounted on said j aw holder by a member which extends through said j aw and said resilient sleeve.
This arrangement enables the jaw to be correctly aligned with the surface of a pipe.
For a better understanding of the invention refer¬ ence will now be made, by way of example, to the accom¬ panying drawings in which:-
Figure 1 is a partially cut-away plan view of a power tong in accordance with the invention;
Figure 2 is a plan view of a jaw mounted on an alternative jaw holder; and
Figure 3 is a cross-section taken along line III- III of Figure 2. Referring to Figure 1, there is shown a power tong which is generally identified by reference numeral 1. The power tong 1 comprises a housing 2 in which is mounted a rotary 3 rotatable by an hydraulic motor 4 acting through a gear train (not shown) including gear wheels 5 and 6.
The rotary 3 is provided with two passive jaws 7 and 8 and an active jaw 9.
Passive jaw 7 is held in a jaw holder 10 which is slidably mounted in a recess 11 in the rotary 3. The jaw holder 10 is provided with a threaded bore 12 which engages corresponding threads in a threaded shaft 13. The threaded shaft 13 has a plate 14 which bears against the inner wall of the rotary 3 and a drive spindle 15 which is provided with a socket (not shown). An hydraulic actuator 16 is mounted on the housing 2 and is provided with a drive shaft 17 which can be advanced radially into engagement with the socket in the drive spindle 15.
The hydraulic actuator 16 can also be driven to rotate drive shaft 17 by a required number of turns. When drive shaft 17 is rotated in one sense jaw holder 10 moves radially inwardly whilst when drive shaft 17 is rotated in the opposite sense jaw holder 10 moves radi¬ ally outwardly. The jaw 8 is associated with a similar positioning
arrangement which is controlled by hydraulic actuator 18. At the commencement of a screwing operation jaws 7 and 8 are fully retracted and gate 19 is opened. Power tong 1 is then advanced until pipe 20 enters the opening left by the gate 19 and occupies the position shown in the Figure. The diameter of pipe 20 has already been supplied to a control computer (not shown) and when the pipe 20 reaches the position shown gate 19 is closed and hydraulic actuators 16 and 18 are actuated to advance the jaws 7 and 8 into the positions shown. Hydraulic actuators 16 and 18 are then deactivated and their drive shafts retracted under the influence of springs (not show ).
The active jaw 9 is then pressed against the pipe 20 with the desired pressure by introducing hydraulic fluid into twin voids 21 between fixed pistons 22 and respective cylinders 23 formed in an active jaw holder
24 carrying jaw 9.
Once the jaws 7, 8 and 9 have fully gripped the pipe 20, the rotary 2 and pipe 20 can be rotated in unison.
It will be appreciated that the position of jaws 7 and 8 can be rapidly adjusted to suit a variety of pipes of different diameters. Various modifications to the arrangement described are envisaged, for example the diameter of pipe 20 may automatically be measured as it enters the power tong 1 and the position of passive jaws 7 and 8 adjusted auto¬ matically. If desired sensors may be provided to ensure that drive shaft 17 is not advanced until the socket in drive spindle 15 is aligned therewith. A sensor may also be provided to inhibit rotation of the drive shaft 17 until it is fully inserted in the socket. A position sensor may also be provided to independently monitor the posi-
tion of the passive jaws 7 and 8 feeding this information to the computer for making any necessary corrections.
Whilst the threaded bore 12 is preferably provided in the jaw holder 10 it will be appreciated that a threaded shaft could be mounted on the jaw holder and the threaded shaft 13 could be replaced by a rotatable member having a threaded bore to receive the threaded shaft on the jaw holder.
If desired, the jaws may be formed as an integral part of their jaw holders.
Figures 2 and 3 show a jaw 7' which is resiliently mounted in jaw holder 10'.
In particular, a stud 30 having a bore 31 is screwed into the jaw holder 10'. The bore 31 is lined with a sleeve 32 of resilient material. The jaw 7' has a central recess 33 which receives the free end of the stud 30. The jaw 7* is retained by a socket screw 34 which has a shank 35 and a tip 36 which threadedly engages the sleeve 32. Resilient material 37, 38 is also placed as shown. The sleeve 32 of resilient material together with the resilient material 37, 38 enables the jaw 7' to make limited movements relative to the jaw holder 10' so that it can become properly aligned with the pipe being gripped. It will be appreciated that, as an alternative, the socket screw 34 could threadedly engage the jaw 7' and the free end portion of the socket screw 34 extend into the resilient sleeve 32. In such an embodiment the free end portion of the socket screw 32 would preferably be thread free.
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