JPS5839629B2 - power tongs - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power wrenches, and more particularly to power tongs for use in make-up and breakout operations of threaded connections between adjacent tubular members.

More particularly, the present invention relates to a mechanism for firmly and uniformly engaging the grasping element of an open power tong to a tube so that the tube rotates smoothly about its axis.

BACKGROUND OF THE INVENTION Tubular members used in the oil field, such as drill pipes and casings, are utilized in sections that are joined together at their ends using threaded fittings.

The power tongs described here are used for make-up and play-out operations on these threaded fittings, and are used to firmly grasp one tubular member and pull it against the adjacent member. It is driven by rotation.

Tongs having such functionality in the industry are described in U.S. Pat. ing.

The camming action normally used to bring the gripping element or die into contact with the tube often misaligns the tube with respect to the center of rotation of the tongs.

That is, the tube is often not driven in rotation about its axis.

This mismatch and the resulting vibrations place severe limitations on the rotational speed that can be applied to the tube, and in extreme cases can compromise the safety of the tube or tongs and the operator.

There is therefore a strong need for power tongs for pipes that have means for firmly and uniformly engaging the pipe so that the pipe rotates smoothly about its axis.

In accordance with the present invention, a new tube power tong is provided having a tube grasping assembly for holding the tube concentrically with a rotating gear.

In some embodiments, the tongs include a frame having a throat at a distal end, a mouth adapted to be aligned with the throat, and a power-driven rotary gear rotatably mounted on the frame. and a pair of jaws that are mounted on both sides of the center line of the tongs so that they can swing, and whose swing fulcrum is located behind the center of rotation of the rotating gear, and a pair of jaws that are attached to each jaw. a cam follower, a tube gripping element supported by the jaws, and at least one pair of opposing cam surfaces provided on the inner surface of the rotary gear, the paired cam surfaces being configured to cooperate; Therefore, when the cam follower is performing a cam action at a point on the opposing cam surface, the jaws are positioned so that the axis of the tube piece held between the jaws coincides with the center of the rotating gear. It consists of a cam surface that is

According to the invention, the inner surface of the gear is formed by a means for rotationally driven around a central gear axis by a suitable drive system and a central opening for enclosing a tube piece to be gripped for rotational purposes. a central aperture that aligns with the tong aperture during tube installation and removal, and at least a pair of diametrically spaced and opposed cam surfaces on the inner surface of the rotary gear; The cam surfaces are asymmetrical with respect to the diameter connecting the cam surfaces, so that the angle at which each cam follower travels along the two opposing cam surfaces during make-up and breakout operations is A new rotary gear is also provided, characterized in that it consists of a cam surface, in which the difference in the cam surface is adapted to be compensated for.

Therefore, a first feature of the invention is to provide a firm and uniform engagement of the gripping element against the tube in order to prevent dangerous vibrations by smoothly rotating the tube about its axis. It is an object of the present invention to provide a power tongs having a means for

This feature is achieved by providing opposed cam surfaces with different curvatures to compensate for the angular differences when the cam followers travel along their respective cam surfaces during make-up and break amp operations. be done.

These and other features and advantages of the invention will become apparent from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings.

Referring now to the drawings, and in particular to FIG. 1, a perspective view of an apertured power tong 10 constructed in accordance with the present invention is shown.

Tong 10 has a frame 12 consisting of an upper surface and a lower surface connected by side walls.

The upper and lower surfaces include upper and lower cage plates 14.16 that pivotally support the jaws described below.

Frame 12 defines a front throat 18 for receiving the tube piece.

When the tube piece is centrally located inside the frame during operation, the throat 18 is closed by means of a swingably mounted door member 20.22, as is well known to those skilled in the art.

The tube grasping assembly will now be described with reference to FIGS. 1-3.

A rotary gear 30 is mounted inside the frame 12 so as to be rotatable relative to the frame.

Since the rotating gear 30 has teeth (not shown) on its outer periphery, as is well known to those skilled in the art,
For example, it is driven by a plurality of pinion gears.

The pinion gear is, for example, U.S. Patent No. 2,879,680.
It is driven by a hydraulic drive such as that described in No.

The inner surface of the rotary gear 30 has camming means consisting of a curved camming surface 70, 7L72, 73 for pressing the tube gripping element into contact with the tube.

In the illustrated embodiment, the tube gripping element has dies 36, 37, 38, 39 mounted on a pair of swingably mounted jaws 44, 46.

The jaws are pushed toward the tube by cam followers consisting of jaw rollers 50, 52 rotatably mounted on the jaws by pins 56,58.

The rollers 50,52 are attached to the cam surface 70 on the inner surface of the rotating gear 30.
, 71, 72, 73.

The jaws are swingably mounted at points P and P' near the rear of the tongs.

The rear die 36, 38 is located near the pivot point, so that even when a tube piece, e.g. tube piece 59, is inserted into the tongs, the rearward movement of the tube piece, as shown in FIG. It is stopped by 36.38.

The front dies 37 and 39 are located in front of a horizontal straight line X (FIG. 2) passing through the axis of the rotary gear 30 and perpendicular to the center line CL of the throat.

Therefore, when the jaws are pushed toward the tube into the grasping position, as shown in FIG. It will be grasped on the front side and the rear side of straight line X.

Stated another way, it is preferred that the die grasp the tube in each of the four quadrants separated by lines X and CL.

The rear dies 36, 38 are close to the pivot points P, P' of the jaws and therefore move only slightly during the gripping operation.

However, when the cam is actuated, the attitude angle of the rear dies 36, 3B changes sufficiently so that the dies contact the tube at the correct engagement angle.

As previously mentioned, the present invention is designed to allow the die to grip the tube so that it is centered on the rotating gear, thereby providing relatively smooth and safe rotation of the tube during make-up and breakout operations. It mainly concerns improved means of.

The improvements of the present invention will be more easily understood by first analyzing the conventional tube grasping assembly shown in FIGS. 4 and 5.

According to the illustrated conventional scheme, the cam surfaces on the inner surface of rotating gear 30' are arranged in opposing cam surface pairs 60, 62 and 6.
Consists of L63.

Cam surfaces 60 and 63 form part of a circle having a center at point C on straight line X.

Cam surfaces 61 and 62 form part of a circle having its center at point C on straight line X.

The radii of the four cam arcs are equal.

Therefore, the curvature of the opposing cam pairs operating during a make-up or breakout operation is equal.

As previously mentioned, when using a symmetrical tube gripping assembly such as that shown in FIG. No.

In other words, the jaws must be rotated by the same angle about their respective pivot points when grasping the tube.

However, as shown in FIG. 5, when the tube is grasped according to the conventional method, the axis of the tube is not at the center of the rotating gear.

This allows opposing cam surfaces, such as cam surfaces 60 and 62, to have different "angles of attack" (a) on each jaw roller.
This is due to the fact that the opposite jaw rollers 50', 52' are pressed against the tube by different amounts of movement due to the "ngle of attack" action.

This phenomenon may be best understood by visualizing the movement of opposing cam surfaces, such as cam surfaces 60 and 62, during a normal makeup application.

At the start of the operation, the jaw rollers 50', 52' are in neutral recesses on both sides of the rotating gear.

When the rotary gear begins to move, for example, clockwise, toward the pre-engaged position shown in FIG. moving away from the dynamic fulcrum P', so that the rollers act at different effective cam pitches.

The jaw rollers 50', 52' are therefore forced toward the tube at different speeds due to the different effective pitches of the cam surfaces.

During the next breakout operation, the other pair of opposing cam surfaces, cam surfaces 61 and 63, act in a similar manner and the tube will be gripped off-center.

The angular travel of jaws 44', 46' is shown in FIG.

In FIG. 5, the initial positions of the centers of the jaw rollers 50', 52' are indicated by crosses.

As shown, jaw 44' moves by an angle Y about its pivot point P, and jaw 46' moves by an angle Z about its pivot point P'.

Because angle Y is somewhat larger than angle Z, tube 59 is gripped in a slightly off-center position as shown in FIG.

In FIG. 5, the reference letter M represents the center of rotation of the rotary gear 30, and the letter N represents the axis of the tube.

As explained below, the purpose of the invention is to bring points M and N closer together.

According to the apparatus of the invention illustrated in FIGS. 2 and 3,
Opposing cam surface pairs, namely pair 70° 72 and pair 71
, 73 do not have the same curvature.

As best shown in FIG. 2, cam surfaces 70 and 73 consist of portions of circles having equal radius R2, each centered at a point A, A'' on line X.

The cam surfaces 71 and 72 are cut out from a part of a circle having the same radius R3, and their centers are at a point B offset from the straight line X.
It's in B'.

In the illustrated embodiment, radius R3 is significantly smaller than radius R2.

In an example of a rotating gear for use with a 7-5/8 inch (194++ m) tongue, the nominal radius of the rotating gear R4 is 68/8 inches (162 mm), R2 is 5.26 inches (134 mm), and R3 is 5. .06 inch (129mm)
, and points B and B' are offset from straight line X by a distance of approximately 0.40 inches (10 mm).

The operation of the illustrated tube grasping assembly will be best understood by reference to FIGS. 2 and 3.

In FIG. 2, the jaw rollers 50.52 are in the intermediate recess as the tube is moved into position to be received by the tongs and contact the rear die 36,38.

As the rotary gear rotates clockwise to the tube gripping position shown in FIG. 3, the jaw rollers 50,52 run along their respective cam surfaces 71.73 and push the die into gripping contact with the tube.

Since the cam surface 71 is moving toward the pivot point P of the jaw 44, the cam effect of this cam surface is compared with that of the opposing cam surface, if both cam surfaces are the same. , the cam effect becomes somewhat weaker.

However, as shown in FIGS. 2 and 3, the curvature of the cam surface 71 is larger than that of the cam 73, so the jaw roller 50
52 will run along a cam of equal effective pitch, so that jaw 44 approaches the grasping position of FIG. 3 at the same speed as jaw 46.

As shown in FIG. 3, while moving from the neutral position to the engaged position, both jaws 50, 52 again travel by U,
For this reason, the rotation center M of the rotary gear coincides with the axis N of the tube.

The general idea of the invention is to use only one tong for a wide range of pipe diameters from drill pipe to casing.

To achieve this flexibility, each tong is provided with several pairs of jaws for each size of tube to be grasped.

FIG. 6 shows the same power tong gripping assembly as shown in FIGS. 2 and 3, but with dies 136, 137, 138 instead of jaws 44, 46 adapted to grip a smaller tube 160. 144 and 146 with a .138 diameter are shown installed.

The rotating gear 30 remains unchanged.

The jaws can be replaced by removing the jaw retaining bolts at pivot points P and P'.

In accordance with the invention, each pair of jaws, such as jaws 144
, 146 are preferably constructed so that the jaw rollers are always at approximately the same point on the cam surface when the die grips the tube that fits the die.

By doing so, the improved camming surface of the present invention provides the advantages described above no matter what size jaws are used on the tongs.

The position of the jaw rollers on the cam surface when gripping the tube will change if the tube is too small or too large.

However, when the diameter of the tube is within a reasonable tolerance, the cam surface is long enough that the jaw rollers will not move at any point on the cam surface, whether the tube is too small or too large. It is understood in the state that it is.

Therefore, the jaw roller has a certain length, e.g.
A grasp condition occurs at any point in the length range of ~3 inches (between 51 and 76 inches).

The term "cam surface area" that has been used so far refers to this range of constant length that is expected when gripping cam action occurs.

The adjacent area on the inner surface of the rotating gear may be curved or have any other shape as long as it smoothly moves the cam follower (jaw roller) to the cam surface; It refers only to the length range in which the gripping cam action occurs between the node and the inner surface of the rotating gear.

Opposing jaws 44, 46 are displaced by an equal distance (i.e. rotated by an equal angle of rotation about points P, P' whenever the jaw rollers are located at any point on the cam surface). It is desirable that

Regardless of the shape chosen for the cam surface on the rotating gear 30, the opposing cam surface has a unique shape that causes the opposing jaws to move toward the tube at the same speed. Exist against.

This corresponds to the normal state of symmetry with respect to the straight line CL, that is, the jaws have the same size and shape, the dies are the same, and the swing supports P and P' are in a mirror position relationship with respect to the straight line CL. This applies when you are in a situation where you are.

However, even if the cam surface is not strictly symmetrical with respect to the straight line CL, there is a unique shape that exhibits the advantages of the present invention with respect to the opposing cam surfaces.

However, the shape will be different from the shape if symmetry exists.

The precise cam mechanism illustrated in FIGS. 2 and 3 is merely an example.

It is also possible to devise other cam shapes.

Importantly, the opposing cam surfaces are cooperating so that when the cam followers (jaw rollers) are at two points along the opposing cam surfaces, The opposing jaws are adapted to move so that the tube gripped therebetween is centered within the rotating gear.

In the normal case of symmetry about the straight line CL, the jaws rotate by the same angle of rotation about their respective pivot points whenever the jaw rollers are on the cam surface.

Although the invention has been described in connection with one embodiment, many modifications are possible without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an aperture-type power tong constructed in accordance with the present invention. FIG. 2 is a plan view of the tong tube gripping assembly of the present invention, comprising jaws, jaw rollers, gripping dies, and the inner surface of a rotating gear, with the jaws open and in a neutral position for receiving the tube; (This is true. Figure 3 is a diagram similar to Figure 2, showing the state in which the tube is firmly held by the tube gripping assembly IJ (thereby, the axis of the tube is aligned with the center of the rotating gear). FIG. 4 is a view similar to FIG. 2, showing a representative conventional curved pipe grasping assembly. FIG. 5 shows the conventional assembly shown in FIG. Fig. 6 shows a tube grasping assembly of the present invention in which large jaws are used to grasp relatively small diameter tubes. 10... Power Tongs, 12... Frame,
14... Upper cage plate, 16... Lower cage plate, 18... Front throat, 30...
・Rotating gear, 36, 37° 3B, 39, 136, 13
7,138. and 139...Dice 44,
46, 144 and 146... Jaw 50 and 52... Jaw roller, 70, 71, 72
and 73...cam surface.

Claims (1)

[Scope of Claims] 1. A power tong of the open type, which has a frame having a throat at its tip, a mouth aligned with the throat, and is rotatably mounted on the frame. A power-driven rotary gear, a pair of jaws located on both sides of the center line of the tongs so as to be able to swing, and whose rocking fulcrum is located behind the center of rotation of the rotary gear; a cam follower associated with the jaw, a tube gripping element supported by the jaw, and at least one pair of opposing cam surfaces provided on the inner surface of the rotating gear;
The paired cam surfaces are shaped to cooperate so that when the cam followers are camming at points on the opposing cam surfaces, the tube piece gripped between the jaws is and a cam surface on which the jaw is positioned such that its center coincides with the rotating gear, and at least one pair of the opposing cam surfaces lie on a straight line X that is perpendicular to the center line of the throat and passes through the center of the rotating gear. a first cam surface formed by a portion of a first circle having a center at , the center being at a position offset from the straight line X on the opposite side with respect to the centerline of the throat and having a radius smaller than the first circle; and a second cam surface formed by a portion of a second circle. 2. the pair of jaws pivot about a fulcrum located symmetrically with respect to the centerline of the tongs, and the jaws and the tube gripping element associated with the jaws are of substantially the same shape and size and are opposed; The cam surfaces are cooperating so that when the cam followers are camming at points on the opposing cam surfaces, the opposing jaws are directed toward the tube piece by substantially the same angle. The power tongs according to claim 1, which is adapted to swing toward. 2. A power tong according to claim 1, wherein there are 32 pairs of opposing cam surfaces, the first pair for joint make-up operations and the second pair for joint breakout operations. 4. A frame having a throat for receiving the tube, a rotating gear mounted on the frame, means for driving the rotating gear one rotation, and on the inner surface of the rotating gear comprising two pairs of opposing cam surfaces. cam means provided, a pair of pivotally mounted jaws supporting a die adapted to engage the outer surface of the tube, and a pair of swingably mounted jaws running over the cam surface to engage the die against the tube piece; A power tong of the type having a cam follower associated with each jaw adapted to urge into engagement, each pair of opposing cam surfaces diametrically spaced and opposed and cooperating. first and second cam surfaces having a shape, the first cam surface being formed by a portion of a first circle having a center on a straight line X perpendicular to the centerline of the throat and passing through the center of the rotating gear; and the second cam surface is formed by a portion of a second circle whose center is offset from straight line X on the opposite side with respect to the centerline of the throat and has a smaller radius than the first circle. Power tongs characterized by: 5. Power tongs of the type having pivotable opposed jaws which are brought into gripping engagement with the tube piece by the action of a cam follower adapted to run on a cam surface provided on the inner surface of the rotary gear. a rotary gear used in the invention, having means for being driven in rotation about a central gear axis by a suitable drive train, and a central opening surrounding a rotatably gripped tube piece and forming the inner surface of the gear. , an aperture aligned with the tong aperture during tube loading and unloading, and at least one pair of diametrically spaced and opposed cam surfaces on the inner surface of the rotary gear, the first and second opposed cam surfaces being disposed on the inner surface of the rotary gear. one of the cam surfaces is defined by a first circular portion having a center on a straight line X passing through the center of the rotating gear and perpendicular to the centerline of the throat; a cam surface is defined by a portion of a second circle having a smaller radius than the first circle, the center of the second circle being located on an opposite side of the centerline of the throat and extending from the straight line; and at least one pair of cam surfaces offset from the X.