Handling: hand and hoist-line implements – Hook – hoistline – or grab type – Locking device
Reexamination Certificate
1999-07-13
2001-08-07
Kramer, Dean J. (Department: 2167)
Handling: hand and hoist-line implements
Hook, hoistline, or grab type
Locking device
C294S119100
Reexamination Certificate
active
06270136
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to oil tools for making and breaking tubular connections used in the oil industry. More particularly it relates to a back-up tong for grasping tubular elements, e.g. pipe, casing or completion tubing in the oil well equipment art.
BACKGROUND TO THE INVENTION
In oil well drilling equipment the coupling and uncoupling, or so-called “making” and “breaking” of the connection on tubular is usually effected by pipe gripping tongs. The lower pipe section is usually gripped and held against rotation by a “back-up” tong and the upper pipe section is usually gripped and rotated by an upper “break-out” or “make-up” tong.
A variety of mechanical arrangements have been employed to advance the jaws within a back-up tong in order for such jaws to engage with and grasp the tubular. In U.S. Pat. No. 4,647,777 three jaws are advanced radially inwardly along linear paths by the direct application of hydraulic pressure to the jaws. In U.S. Pat. No. 4,402,239 a pair of opposed jaws are advanced radially inwardly by hinged linkages connected to a hydraulic cylinder. In U.S. Pat. No. 4,778,742 the jaws are carried on hinged supports and are driven inwardly along arcuate paths by the rotation of the supports under hydraulic pressure. Lastly, in U.S. Pat. No. 4,290,304 a pair of opposed jaws are driven radially inwardly by the rotational advancement of a crescent-shaped wedge carried on a “C”-shaped ring that is turned through gearing linked to a hydraulic motor.
In all of the above cases the mechanical systems transmit a force to the jaws that is dependent on the position and shape of the parts, following a single, fixed force-application schedule. While pipe of slight variations in diameter may be accommodated without a change of parts, if pipe of substantially different diameter is to be grasped, major parts must be changed to adjust the schedule by which the force is applied. This is a separate consideration from that of using interchangeable jaws to provide grasping surfaces that accommodate pipes of differing diameters.
It is an object of this invention to provide a mechanical layout for tongs that accommodates the use of a wedge or combination of wedges to place a gripping apparatus about a tubular surface and apply a gripping force thereto. The ready inter-changeability not only of jaws but also of intermediate components that govern the schedule by which force is applied to pipe with the advance of the jaws within a tong render the invention convenient and advantageous.
The invention in its general form will first be described, and then its implementation in terms of specific embodiments will be detailed with reference to the drawings following hereafter. These embodiments are intended to demonstrate the principle of the invention, and the manner of its implementation. The invention in its broadest and more specific forms will then be further described, and defined, in each of the individual claims which conclude this Specification.
SUMMARY OF THE INVENTION
According to one aspect of the invention a tong for grasping tubular members is provided that includes:
(1) a frame having a central pipe opening with a center region and an entry throat for receiving a tubular member to be grasped;
(2) a thrust-receiving jaw carried by a thrust-receiving jaw support that is attached to the frame for fixing the position of the fixed jaw within the pipe opening;
(3) a displaceable jaw assembly containing a radially displaceable pipe-engaging jaw mounted at the inner jaw end of a jaw carrier shaft for advancement of the jaw into the pipe opening;
(4) a wedge with two face surfaces, one of said face surfaces being positioned against the outer wedge end of the jaw carrier shaft, opposite the jaw end;
(5) a thrusting seat coupled to the frame and contacted by the other of the face surfaces of the wedge; and
(6) a linear actuator anchored at one end to the frame and aligned at its other end to move the wedge forward between the outer wedge end of the jaw carrier shaft and the thrusting seat for advancement of the displaceable jaw radially towards the center of the pipe opening,
whereby activation of said hydraulic actuator for movement of the wedge will advance the jaw carrier shaft and move the displaceable jaw inwardly with respect to the pipe opening to grasp a tubular member contained therein.
To permit the access of pipe to the pipe opening, an entry throat with a gate is provided. The thrust-receiving jaw may be carried by a hinged jaw support connected to the frame which serves as a gate. The hinged jaw support may be swung so as to allow the thrust-receiving jaw to retire and expose the entry throat for pipe to be placed within the pipe opening. With pipe in position within the pipe opening the hinged jaw support may be swung to close the entry throat and position the thrust-receiving jaw so that it is directed towards the pipe or other tubular member that is to be grasped. The hinged jaw support is latched in place during pipe engagement.
The thrust-receiving jaw may be permanently fixed against radial displacement towards and away from the pipe opening. Or it may be adjustable as to its location in order to permit it to occupy a series of fixed positions with respect to the pipe opening. Such adjustable locations may be used to accommodate various ranges of pipes.
The thrust-receiving jaw is preferably adjustable in its radial position with respect to the pipe opening by a screw type adjustable jaw positioning means carried within the hinged jaw support. The jaw positioning means will normally be adjusted so that when the thrust-receiving jaw contacts the pipe, the pipe is approximately centered about the center line of the pipe opening. In this manner, a range of pipe diameters can be accommodated.
As a further feature, the jaw assembly and linear actuator may be rendered repositionable with respect to the frame to permit the accommodation of a larger range of pipe sizes.
The jaw of the displaceable jaw assembly may also be interchangeable to permit substitution of jaws dimensioned to engage with pipes of differing diameters. Further, the wedge may be interchangeable to control the schedule of force being applied by the jaw to pipe.
The jaw assembly includes a jaw carrier shaft that is constrained by guide surfaces carried by the frame to allow the jaw to advance radially towards and away from the pipe opening. The jaw assembly preferably includes means by which the jaw will spontaneously retreat, out of the pipe opening, when the wedge is caused to withdraw under the reverse action of the linear actuator. To provide resilience, a spring means operates to bias the jaw outwardly, away from the pipe opening, to the limit of its marginally permitted displacement with respect to the jaw assembly. This function may be provided through a spring located internally within the jaw carrier shaft. While the prior art has employed a spring attached externally to the jaw and mounted to the outer frame, this new arrangement of the invention avoids exposing the spring to the outside environment, and reduces interference with the operation of the tong.
The jaw assembly and its associated actuator may be displaceable within the body of the tong to allow the tong to accommodate an exceptionally broad range of tubular diameters.
The linear actuator may be in the form of a hydraulic cylinder. Or it may be in the form of a motor and worm gear drive or other equivalent performing apparatus.
The tong of the invention may have a single displaceable jaw or multiple displaceable jaws. When a single jaw is employed, the thrust-receiving jaw may be positioned at the inner side of the pipe opening, facing the throat, and the displaceable jaw may be carried by the hinged jaw support that swings in place across the throat.
Each displaceable jaw will have an associated wedge. However, multiple wedges may be advanced by a single linear actuator.
Normally, a single wedge will be driven by a single linear actuator. However, the wedging action may be arranged to arise through the use of mul
Farr Canada Ltd.
French David J.
Kramer Dean J.
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