JP6504110B2 - Jaw for a clamping device and method of fixing the same - Google Patents

Description

  The present invention relates to a jaw for use in a clamping device for clamping a coupling to a steel pipe having a screw at the pipe end (e.g. an oil well pipe etc.) and to a method of fixing it to the key of the clamping device.

  Steel pipes used in wells that mine oil and natural gas (so-called oil wells) are called oil well pipes, and at the oil well pipe manufacturing plant, the coupling is tightened on the pipe end screw (hereinafter referred to as pipe end screw) Shipped in The clamping device used when clamping the coupling in a manufacturing plant for oil well tubes comprises a chuck for holding the oil well pipe (hereinafter referred to as a pipe chuck) and a chuck for holding the coupling (hereinafter referred to as a coupling chuck) The coupling chuck is configured to be rotated and screwed by rotating the coupling chuck while holding the oil well pipe in a predetermined position by the pipe chuck.

  That is, while the clamping is performed, the relative positional relationship between the oil well pipe and the pipe chuck, and the relative positional relationship between the coupling and the coupling chuck are constant. On each chuck, a plurality of jigs (hereinafter referred to as jaws) to be in contact with the oil well pipe and the coupling are fixed to the chuck through a key, and the high strength metal jaws are used for the oil well pipe and the coupling It is configured to be in close contact with and gripped.

  If slippage occurs during tightening of the coupling, it will result in poor tightening, leading to a decrease in the yield of the well. Therefore, in order to prevent slippage, use jaws with claws on the surface of the jaws in close contact with the oil well pipe and coupling (hereinafter referred to as the tightening adhesion surface), and clamp the claws on the oil well pipe and coupling. ing. Therefore, there is a problem that surface defects caused by the jaws are easily generated in the oil well pipe and the coupling.

  In recent years, with regard to petroleum resources, reserves capable of being mined in shallow oil wells (so-called shallow wells) have decreased, and drilling of deep oil wells (so-called deep wells) has been promoted. In deep wells, since oil resources are mined from the deep part which is in a high temperature and corrosive environment, using an oil well pipe or coupling with a surface weir, in addition to the same problems as the above-mentioned shallow wells, There is a fear that corrosion will progress from In a shallow well, there is a risk that workers may be injured by surface defects or cracks may occur from surface defects at the site of oil wells.

In order to solve this problem, techniques for preventing surface defects due to tightening of oil well pipes and couplings are being studied.
For example, a technique of sticking the non-slip tape disclosed in Patent Document 1 on the contact surface of the jaw and performing tightening is being studied. However, if tightening is performed about 200 times, there is a problem that the non-slip tape is broken or peeled off. That is, since it is necessary to replace the non-slip tape every 200 oil well pipes, the productivity of the oil well pipes is lowered.
In addition, although a technology has been developed in which WC (tungsten carbide) is electrodeposited on the tightening adhesion surface for tightening, there is a problem that fine wrinkles are easily generated in oil well pipes and couplings.

Japanese Patent Laid-Open No. 6-206447

  The present invention solves the problems of the prior art and can prevent the surface flaw of the oil well pipe and the coupling when the oil well pipe and the coupling are tightened, and the tightening device has excellent durability. It is an object of the present invention to provide a jaw for and a fixing method for fixing it to a key.

The present inventor uses a softer material than the high-strength metal conventionally used widely as a material of the jaw to study a technique for preventing surface flaws in oil well tubes and couplings. Various jaws made of rubber were manufactured and experiments of tightening of the oil well tube and the coupling were performed. And the urethane rubber jaw is
(A) Fix the jaws provided with arc-shaped tightening contact surfaces that match the outer diameter of the oil well pipe and the outer diameter of the coupling to the keys, and attach the keys to the pipe chuck and the coupling chuck for tightening. By doing so, the clamping contact surface of the jaws adheres to the oil well pipe and the coupling, and it is possible to prevent slippage from occurring during tightening.
(B) Even if the jaws are in close contact during tightening, the jaws are soft, so no surface flaws on the oil well pipe or coupling occur.
(C) Urethane rubber is a material with excellent wear resistance, so the effect of improving the durability of the jaws can be obtained.
(D) By devising means for fixing the jaws to the steel key, it is possible to prevent concentration of stress on the key-jaw junction, which in turn causes the jaws to crack. It has been found to have the advantage of being able to prevent

The present invention has been made based on such findings.
That is, the present invention is a jaw that is attached via a key to a chuck of a clamping device that clamps a pipe end screw of an oil well pipe and a coupling, and grips the oil well pipe or the coupling during clamping. It is a rubber jaw.

  In the jaw of the present invention, a through hole is provided which penetrates from the key fixing surface on the side fixed to the key to the tightening and sealing surface on the side close to the oil well pipe or the coupling. And insert a cylindrical washer shorter than the length of the through hole into the through hole and secure the washer with an adhesive at a position sunk from the tightening contact surface and key fixing surface, and screw the bolt to the inner surface of the washer It is preferable to provide a screw for bolting. Furthermore, it is preferable that the tightening contact surface be curved in a circular arc with the same curvature as the outer diameter of the oil well pipe or coupling, and the tightening contact surface have a plurality of grooves parallel to the center axis of the oil well pipe or coupling. Is preferred.

  The present invention also relates to a method of fixing a jaw for holding the well or the coupling when the well end of the well is tightened with the coupling, to the key attached to the chuck of the clamping device. It is made of urethane rubber and has a through hole penetrating from the key fixing surface on the side fixed to the key to the tightening adhesion surface on the side to be in close contact with the oil well pipe or coupling, and has the same outer diameter as the inner diameter of the through hole. Then insert a cylindrical washer shorter than the length of the through hole into the through hole and secure the washer with an adhesive at a position buried from the tightening contact surface and the key fixing surface, and provide a screw for bolt on the inner surface of the washer This is a method of fixing the jaws by inserting and screwing a bolt from the key fixing surface side, and holding and fixing an L-shaped bent claw of the key between the hexagonal head of the bolt and the key fixing surface.

  According to the present invention, it is possible to prevent the surface flaws of the oil well pipe and the coupling when tightening the oil well pipe and the coupling, and moreover, since the jaw can be used for a long period of time, the industrially significant effect Play.

It is a sectional view showing typically an example which fixes a jaw concerning the present invention to a zipper. It is a sectional view showing typically an example which fixes a jaw concerning the present invention to a zipper.

  FIG. 1 is a cross-sectional view schematically showing an example of fixing a jaw according to the present invention to a chuck. The jaw 1 is made of urethane rubber and has a through hole 4. Urethane rubber is a material excellent in abrasion resistance, and therefore has the effect of enhancing the durability of the jaws. The shape and dimensions of the jaw 1 are not particularly limited, and are appropriately set in accordance with the outer diameter of the oil well pipe or coupling to be clamped, the equipment specification of the clamping device, the configuration of the chuck 2 and the like. In the following, the term "chuck" will be referred to as a generic term for a pipe chuck and a coupling chuck.

The through hole 4 is a surface 1 a of the jaw 1 fixed to the key 3 (hereinafter referred to as a key fixing surface) and a surface 1 b of the jaw 1 contacting the oil well pipe or the coupling (hereinafter referred to as a tightening contact surface). It is provided to penetrate up to.
Even when the tightening contact surface 1b is flat, the urethane rubber jaw 1 is deformed at the time of tightening to be in close contact with the oil well pipe or the coupling, so that it is possible to prevent slippage at the time of tightening. However, the contact area can be sufficiently secured by curving the tight joint surface 1b in an arc shape (see FIG. 1) with the same curvature as the outer diameter of the oil well pipe or coupling, so the oil well pipe or coupling during tightening The adhesion between the two and the jaw 1 is improved.

  A cylindrical washer 5 is inserted into the through hole 4. The inner surface of the washer 5 has a screw (hereinafter referred to as a bolt screw) for screwing a bolt described later, and the outer diameter of the washer 5 is the same as the inner diameter of the through hole 4. Therefore, since the outer surface of the washer 5 and the inner surface of the through hole 4 are in close contact with each other, the jaw 1 can maintain a stable posture. Furthermore, by fixing the washer 5 and the through hole 4 with an adhesive, it is possible to prevent the jaw 1 from falling off during tightening.

The length of the washer 5 is shorter than the length of the through hole 4, and the washer 5 is fixed at a position buried in the through hole 4 so that the washer 5 does not protrude from the key fixing surface 1a and the tightening contact surface 1b. That is, the washer 5 can be prevented from coming into contact with the oil well pipe or the coupling by fixing the washer 5 at a position buried from the tightening contact surface 1b, and thus surface creases are generated in the oil well pipe or the coupling during tightening. Can be prevented. Further, by fixing the washer 5 at a position buried from the key fixing surface 1a, the washer 5 can be prevented from coming into contact with the key 3, and as a result, the jaw 1 can be maintained in a stable posture.
Then, insert the bolt 6 from the key fixing surface 1 a side and screw it with the bolt screw on the inner surface of the washer 5, and between the hexagonal head 6 a of the bolt 6 and the key fixing surface 1 a of the jaw 1, L of the key 3 The jaw 1 is fixed to the key 3 by holding the claw portion 3a bent in a letter shape.

  In this manner, by screwing the bolt 6 to the washer 5 fixed in the through hole 4, it is possible to prevent concentration of stress on the joint between the key 3 and the jaw 1 at the time of tightening. As a result, it is possible to prevent the occurrence of a crack in the jaw 1 from the joint. That is, the effect of enhancing the durability of the jaw 1 can be obtained by distributing the stress generated during tightening.

  With the jaw 1 fixed to the key 3, the end 6b of the bolt 6 on the opposite side to the hexagonal head 6a (hereinafter referred to as bolt end) may protrude from the washer 5, but it protrudes from the tightening contact surface 1b Do not set the length of bolt 6. In other words, the bolt end 6b is tightened and buried from the contact surface 1b, so that the bolt end 6b can be prevented from coming into contact with the oil well pipe or coupling. As a result, surface flaws occur on the oil well pipe or coupling during tightening. You can prevent it. Furthermore, even if the jaw 1 is deformed during tightening, the bolt end 6b is embedded in the washer 5 by using the bolt 6 whose length is set so that the bolt end 6b does not protrude from the washer 5 either. It is possible to prevent the bolt end 6b from coming into contact with the oil well pipe or the coupling.

  The cross section of the key 3 has a trapezoidal shape, and the key 3 and the chuck 2 are fixed (see FIG. 1) by fitting the key 3 into the chuck 2 having a recess of the same shape as the bottom. Thus, the jaw 1 is fixed to the chuck 2 via the key 3.

  FIG. 2 is a cross-sectional view schematically showing an example in which a plurality of grooves 7 are provided in the tightening contact surface 1b of the jaw 1 shown in FIG. The groove 7 is provided parallel to the central axis of the well bore or coupling to be tightened. By providing the groove 7 in this manner, it is possible to increase the friction between the tightening contact surface 1b and the oil well pipe or the coupling, and to control the torque and the rotational speed at the time of tightening with high accuracy. The shape and size of the groove 7 are not particularly limited, and may be set appropriately according to the outer diameter of the oil well pipe and coupling to be tightened, the equipment specification of the tightening device, the configuration of the chuck 2 and the like.

Although the jaw 1 shown in FIG. 2 is also fixed to the chuck 2 through the key 3, its configuration is the same as that of FIG.
The jaw 1 of the present invention can be mounted on either a pipe chuck or a coupling chuck.

  The urethane rubber jaws shown in FIG. 1 were attached to the pipe chuck, and the urethane rubber jaws shown in FIG. 2 were attached to the coupling chuck, and the oil well pipe and the coupling were tightened (500 times). During that time, there was no equipment failure related to the chuck or key, and all the torques and rotational speeds at tightening were within the specified ranges, and the operation was smooth.

  Thereafter, the jaws were removed from the pipe chuck and the coupling chuck, and the surface of the jaws was visually observed to investigate the presence or absence of cracks or defects. As a result, it was confirmed that the jaws of the present invention did not have cracks or fractures and had excellent durability.

  Next, the surfaces of the tightened oil well pipe and the coupling were visually observed to investigate the presence or absence of surface flaws. As a result, no surface wrinkles were observed. That is, it has been confirmed that surface tightening of the oil well pipe and the coupling can be prevented by performing the tightening using the jaw according to the present invention.

1 Joe
1a Key fixed surface
1b Tightening contact surface 2 Chuck 3 key
3a claw 4 through hole 5 washer 6 bolt
6a hex head
6b bolt end 7 groove

Claims (4)

A jaw mounted on a chuck of a clamping device for clamping a well end of an oil well pipe and a coupling via a key and gripping the well or the coupling during the clamping, the jaw being a jaw Ri Do urethane rubber, a through hole penetrating from the keyed surface of the side to be fixed to the key until clamping contact surface on the side in close contact with the oil well pipe or the coupling provided, the same outer and inner diameter of the through hole Inserting a cylindrical washer having a diameter and shorter than the length of the through hole into the through hole and fixing the washer with an adhesive at a position embedded from the tightening contact surface and the key fixing surface; A jaw for a clamping device, comprising a bolt screw for screwing a bolt on the inner surface of the washer . The jaw for a clamping device according to claim 1, wherein the clamping contact surface is curved in an arc shape with the same curvature as the outer diameter of the oil well pipe or the coupling. The jaw for a clamping device according to claim 1 or 2 , further comprising a plurality of grooves parallel to a central axis of the oil well pipe or the coupling on the clamping contact surface. In the fixing method for fixing the well for holding the well or the coupling to the key mounted on the chuck of the clamping device when the well end of the well is clamped to the coupling, urethane rubber is used as the jaw. And a through hole penetrating from the key fixing surface on the side fixed to the key to the tightening adhesion surface on the side well in contact with the oil well pipe or the coupling, and the outer diameter same as the inner diameter of the through hole And inserting a cylindrical washer having a length shorter than the length of the through hole into the through hole and fixing the washer with an adhesive at a position buried from the clamping contact surface and the key fixing surface; A bolt screw is provided on the inner surface of the bolt, and a bolt is inserted and screwed from the key fixing surface side, and the claw bent in an L shape of the key between the hexagonal head of the bolt and the key fixing surface Joe fixing method for the clamping device, characterized in that securing by sandwiching a.

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