HK1155788B - Tricam axial extension to provide gripping tool with improved operational range and capacity - Google Patents

Description

Three-cam axial extension providing improved operating range and capability for gripping tools

Technical Field

The present invention is intended to relate to applications where tubulars or pipe strings must be gripped, operated and lifted with tools that are connected to a drive head or reaction frame to be able to transfer axial and torsional loads to and from the gripped pipe section. The present invention relates to slips (slips) in the field of earth boring, well construction, and well servicing with drilling and workover rigs, and more particularly slips on rigs that use top drives (top drives), and is applied to tubular running tools that are connected to top drives for gripping a proximal section of a tubular string being fitted into, used in, or removed from a wellbore. Such a tubular running tool supports various functions necessary or beneficial for these operations including: quick-engage and release, lift, propel, rotate, and pressurized fluid flows into and out of the tubing string. The present invention provides a linkage (linkage) for extending or improving the grip range of such a tubular running tool.

Background

Until recently, power tongs (power tongs) were a permanent method for running casing strings or pipe strings into and out of oil wells in conjunction with a drill rig hoist system. This power tong method allows such a pipe string, consisting of pipe segments or joints having mating threaded ends, to be made up relatively efficiently by bolting the mating threaded ends together (make-up), forming a threaded connection between successive pipe segments as they are added to the pipe string being installed in the wellbore or, conversely, being removed or disassembled (breakout). However, this power tong method cannot simultaneously support other beneficial functions, such as rotating, pushing, or fluid filling after a pipe segment is added to or removed from the pipe string and while the pipe string is being lowered or raised within the wellbore. The typical deployment of tubulars with tongs also requires personnel deployment at relatively high risk locations, such as on the drill floor or even above the drill floor, on so-called "stabbing tables".

The advent of drilling rigs equipped with top drives has enabled a new method of laying tubulars, particularly casing tubulars, in which the top drive is equipped with a so-called "top drive tubular running tool" to grip and possibly seal between adjacent pipe sections and a top drive drill shaft. (it should be understood that the term top drive drill shaft is generally referred to herein as including such drive string components that may be attached thereto, effectively acting as the distal end of the drill shaft extension) various devices have therefore been developed that generally accomplish the purpose of "top drive casing running". The use of these devices in combination with a top drive allows the casing string to be lifted, rotated, advanced and filled with drilling fluid while being laid, thus eliminating the limitations associated with power tongs. At the same time, the automated operation of the gripping mechanism combined with the inherent advantages of the top drive reduces the level of human intervention required for the process of laying with power tongs and thus improves safety.

In addition, in order to operate and run casing using a top drive tubular running tool, the weight of the pipe string must be transferred from the top drive to the support when an adjacent or active pipe section is added to or removed from an otherwise assembled pipe string. Typically, this function is provided by a "ring wedge clamp" axial load actuated gripping device which utilizes "slips" or jaws which are placed within a hollow "slip bowl" through which the casing is laid, wherein the slip bowl has a frustoconical bore of decreasing diameter in the downward direction and is supported within or on the rig floor. The slips, which act as annular wedges between the pipe segment at the proximal end of the pipe string and the frustoconical inner surface of the slip bowl, then tractively grip the pipe, but slide or move downwardly and radially inwardly on the inner surface of the slip bowl as the weight of the pipe string is transferred to the gripper. Thus, the radial force between the slips and the pipe body is self-excited or self-energized axial load, i.e., there is a positive feedback loop taking into account the independent variable of tractive capacity and the independent variable of string gravity, where the string gravity independent variable is actively fed back to control the radial gripping force, which acts monotonically to control the dependent variable of tractive capacity or resistance to slip. Similarly, make-up and break-out torques applied to the live pipe sections must also be reacted out of the near end of the pipe string being made-up. This function is typically provided by tongs having a gripper that engages the adjacent pipe segment and an arm that is connected to the rig structure by a link, such as a chain or cable, to prevent rotation and thus react torque that is not otherwise reacted by the slips in the slip bowl. Also, the clamping force of such pliers is typically self-energizing or "self-powered" by positive feedback from the applied torque load.

In summary, the gripping tool of PCT patent application CA2006/00710 and us national phase application 11/912,665 may be broadly summarized as a gripping tool comprising a body assembly having a load adapter connected to transfer an axial load to the remainder of the body, or body, the load adapter being adapted to be structurally connected to one of a drive head or reaction frame, and a gripping assembly supported by the body and having a gripper surface, the gripping assembly being provided with actuating means to move or move radially from a retracted position to an engaged position to engage the gripper surface radially tractively with either of an inner surface or an outer surface of a workpiece in response to relative axial movement or axial travel of the body in at least one direction relative to the gripper surface. A linkage is provided to act between the body assembly and the clamp assembly upon relative rotation of the load adapter relative to the clamp surface for at least one stroke, causing relative radial movement of the body relative to the clamp assembly to move the clamp assembly from the retracted position to the engaged position in dependence on the action of the actuating means.

Thus, this clamping tool utilizes a mechanically actuated clamp mechanism to generate a clamping force in response to axial loads or axial stroke actuation of the clamp assembly, which occur with or independent of externally applied axial and torque loads in the form of applied right or left hand torque, which are carried throughout the tool from the load adapter of the body assembly to the clamp surface of the clamp assembly in pulling engagement with the workpiece.

It will be apparent that the utility of this or other similar gripping tools is related to a range of workpiece sizes, typically expressed as the minimum and maximum diameters of the tubular workpiece that can be accommodated between the fully retracted and fully extended clamp surface positions of a given gripping tool, i.e., the radial dimension and radial travel of the gripping surface. The utility of a given gripping tool can be improved if it can accommodate a greater range of workpiece sizes. The present invention is directed to meeting this need for larger radial dimensions and radial travel that are beneficial in applications such as are often encountered when adjusting a gripping tool to lay oilfield tubulars.

Disclosure of Invention

According to one broad aspect of the present invention, an expansion linkage is provided for use with a gripping tool having a gripping surface supported by movable gripping elements to support expansion of the radial stroke and workpiece size that a given gripping gripper can accommodate. This includes a three cam linkage having a cam pair supporting actuation of axial travel by bi-directional rotation and an additional cam linkage to correlate radial travel of the tool holder surface to axial travel.

The three-cam linkage includes:

a drive cam body;

an intermediate cam body;

a driven cam body;

a pair of drive cams acting between the drive cam body and the intermediate cam body; and

a pair of driven cams acting between the intermediate cam body and the driven cam body.

Preferably, the drive cam pair is arranged to be active only with respect to rotation in a first direction of rotation and the driven cam pair is arranged to be active only with respect to rotation in a second direction of rotation, the division of the bi-directional rotary actuation onto the two cam pairs contributing to a greater axial stroke and associated radial stroke for the clamp surface than would be the case if a single cam pair were used in the bi-directional rotary actuated linkage.

Drawings

These and other features of the present invention will become more apparent from the following description with reference to the accompanying drawings, which are for illustrative purposes only and are not intended to limit the scope of the invention in any way to the specific embodiments or embodiments shown. Wherein:

FIG. 1 is a simplified form, partially cut-away, isometric view of a dual-axis, bi-rotation (bi-rotation) actuated external clamp tubular running tool provided with a single cam-to-base configuration cam structure showing right-hand torque applied;

FIG. 2A is a schematic diagram in two-dimensional illustration of the single cam pair basic deployment cam configuration shown in FIG. 1, illustrating the application of right-hand torque;

FIG. 2B is a schematic illustration of the cam structure of FIG. 2A in two-dimensional diagrammatic form showing a left-hand torque applied;

FIG. 3 is a schematic diagram of a three-cam configuration in two-dimensional diagrammatic form, with no torque applied;

FIG. 4A is a schematic diagram of the three-cam configuration of FIG. 3 in two-dimensional diagrammatic form showing right-hand torque applied;

FIG. 4B is a schematic diagram of the three-cam configuration of FIG. 3 in two-dimensional diagrammatic form showing the application of left-hand torque;

FIG. 4C is a schematic illustration in two-dimensional diagrammatic form of the three-cam configuration of FIG. 3 showing axial tension applied in the gripping tool;

FIG. 5A is a schematic diagram of a three-cam configuration with a dog advance cam pair in two-dimensional diagrammatic form showing left hand torque applied;

FIG. 5B is a schematic illustration, in two-dimensional diagrammatic form, of the three-cam configuration of FIG. 5A with a dog advance cam pair showing a small amount of right-hand direction rotation prior to dog advance to a neutral position;

FIG. 5C is a schematic illustration, in two-dimensional diagrammatic form, of the three-cam configuration of FIG. 5A with a dog advance cam pair, showing right-hand torque applied;

FIG. 6A is a schematic illustration in two-dimensional diagrammatic form of the three-cam configuration of FIG. 3 with the latch shown in the latched position;

FIG. 6B is a schematic illustration in two-dimensional diagrammatic form of the three-cam structure of FIG. 3 with the latch shown with right-hand torque applied and the latch disengaged;

FIG. 6C is a schematic illustration in two-dimensional diagrammatic form of the three-cam structure of FIG. 3 with the latch disengaged and a left-hand torque applied;

FIG. 7A is a schematic view of the three-cam structure of FIG. 3 with a lock having locking capability in a two-dimensional pictorial form, shown in a locked position;

FIG. 7B is a schematic view of the three-cam configuration of FIG. 3 with a lock having locking capability in a two-dimensional pictorial form showing a right-hand torque being applied and the latch being disengaged;

FIG. 7C is a schematic view of the three-cam configuration of FIG. 3 with a lock having locking capability in a two-dimensional pictorial form showing the latch disengaged and a left-hand torque applied;

FIG. 7D is a schematic diagram of the three-cam configuration of FIG. 3 with a lock having locking capability in a two-dimensional pictorial format showing the latch disengaged and compression applied due to engagement at the driven cam pair;

FIG. 7E is a schematic view of the three-cam configuration of FIG. 3 with a lock having locking capability in a two-dimensional pictorial form showing the latches disengaged and compression applied by engagement of the drive cam pair;

FIG. 7F is a schematic view of the three-cam configuration of FIG. 3 with a lock having locking capability in a two-dimensional pictorial format showing the latch locked and a right-hand torque applied;

FIG. 8 is an external view of a tubular running tool having a three-cam configuration, shown in a locked position;

FIG. 9 is a cross-sectional view of a tubular running tool having a three-cam configuration shown in a locked position within the proximal end of the workpiece;

FIG. 10A is an exterior view of the three-cam configuration shown in the locked position;

FIG. 10B is a cross-sectional view of the three-cam configuration shown in the locked position;

FIG. 11A is an exterior view of a portion of the latch assembly including the drive cam body, the lock ring and the catch, shown in the locked position;

FIG. 11B is an isometric partial cross-sectional view of a portion of the latch assembly including the driven cam body, the locking ring and the catch, with the assembly shown disengaged;

FIG. 11C is an exterior view of a portion of the latch assembly including the drive cam body, the lock ring and the catch, showing the assembly disengaged;

FIG. 12A is an external view of a three-cam configuration showing right-hand torque applied;

FIG. 12B is a cross-sectional view of a three-cam configuration showing right-hand torque applied;

FIG. 13A is an exterior view of the three-cam configuration showing the latch disengaged and a left hand torque applied;

fig. 13B is a cross-sectional view of the three-cam configuration showing the latch disengaged and a left-hand torque applied.

Detailed Description

General principles

The clamping tool described in PCT patent application CA2006/00710 consists of three main interacting parts or assemblies: 1) a body assembly, 2) a clamping assembly supported by the body assembly, and 3) a linkage acting between the body assembly and the clamping assembly. The body assembly generally provides a structural association of the tool components and includes a load adapter by which loads from the drive head or reaction frame are transferred to or from the remainder of the body assembly or main body. The clamp assembly has a clamp surface, the clamp assembly being supported by the body of the body assembly and being provided with means for radially and tractively engaging the workpiece and the clamp surface in response to relative axial movement or axial movement to move or move the clamp surface from the retracted position to the engaged position. Thus, the clamping assembly acts as an axial load or axial stroke actuated clamp element.

The body is coaxially positioned relative to the workpiece to form an annular space within which an axial stroke actuated clamping assembly is positioned and attached to the body. The clamp surfaces of the clamping assembly are adapted to engage the workpiece in conforming, circumferentially distributed and diametrically opposed, traction. Means to radially displace the clamp surface carried by the clamping assembly is arranged to relate the relative axial displacement or axial stroke of the clamp surface relative to the workpiece in at least one axial direction to a radial displacement or radial stroke and then to generate the associated axial force and the collective opposing radial force such that the radial clamping force on the clamp surface is capable of reacting the applied axial load and torque to the workpiece, wherein the distributed radial clamping force is reacted internally, the apparatus comprising an axial load actuated clamp mechanism wherein the axial load is carried between the drive head or reaction frame and the workpiece; the load adapter, body and clamp elements typically act in series.

A linkage acting between the body assembly and the clamp assembly is adapted to link relative rotation between the load adapter and the clamp surface to axial movement of the clamp assembly and thus radial movement of the clamp surface. An axial load actuated clamp mechanism is thus provided to allow relative rotation between one or both of the axial load bearing interfaces between the load adapter and the main body or between the main body and the clamp element, wherein the relative rotation is limited by at least one rotationally actuated linkage that links the relative rotation between the load adapter and the clamp surface to the axial movement of the clamp element and thus the radial movement of the clamp surface. The linkage may be arranged to provide this relationship between rotation and axial movement in a variety of ways, for example by means of a pivoting linkage arm or rocker body acting between the body assembly and the clamp assembly, but may also be provided in the form of a pair of cams acting between the clamp element and at least one of the main body or the load transfer adapter to readily accommodate and transmit axial and torque loads, resulting or tending to result in rotation, and to promote the generation of radial clamping forces. In a preferred embodiment, the cam pairs with contact surfaces, normally acting in the manner of a cam and cam follower, are arranged to relate their combined relative rotation in at least one direction to the axial movement of the clamp element in a direction tending to tighten the clamp, so that the axial stroke has the same effect as and acts in conjunction with the axial stroke caused by the axial load carried by the clamp element. The application of relative rotation between the drive head or reaction frame and the clamp surface in contact with the workpiece in at least one direction causes radial travel or radial displacement of the clamp surface into engagement with the workpiece, followed by associated axial torque and radial force, such that radial clamping force on the clamp surface can react torque to the workpiece, the apparatus comprising a torque load actuation, such that in combination with said axial load actuation, the clamp mechanism is self-energizing in response to a biaxial combined load in at least one axial direction and at least one tangential or torque direction.

Moreover, according to the teachings of PCT patent application CA2006/00710, the cam assembly can be used in the various devices summarized in table 1, wherein the relative axial movement induced between the driving and driven cams by those assemblies providing the "cam" function in table 1 is related to the relative rotation imparted; the relationship between them depends on the local pitch or helix angle acting on the mating pair of cams. Here, this action must be bidirectional (including right-hand and left-hand actuation) and is provided by a cam assembly consisting of a single pair of cams, shown schematically in said fig. 11B (showing cams used in the base or arrangement 1 configuration of table 1 that may be present in an external gripping tool) as saw-tooth profiles between the mating profile ends of substantially cylindrical and coaxially aligned rigid bodies, reproduced here as fig. 1, fig. 1 showing cam assembly 1 with drive cam 2 and follower cam 3 providing a single pair of cams 4, shown applying right-hand rotation. For ease of illustration herein, we use the convention of "driving" and "driven" cams to provide reference to the relative motion and forces described. These should not be construed as limiting so that the described cam systems may generally be reversed with respect to one another.

Referring now to fig. 2A, the cam assembly 1 is schematically illustrated in a two-dimensional representation, wherein the axial and tangential directions are represented as ordinate and abscissa, respectively, in the representation provided in fig. 2A. Thus, the tangential position represents the circumferential position and the tangential movement represents the rotation. The cam pair 4 is represented by a mating right handed multi-line helical load surface 5 and left handed helical load surface 6, where the load surface 5 is shown as a two-line helical load surface having an intermediate helix angle and the load surface 6 is shown as having a relatively shallow helix angle, i.e. the left handed helical load surface 6 is less pitched than the helical load surface 5, where the intersection of the helical load surfaces 5 and 6 forms a point or apex 7. It will be apparent that as the relative rotation increases in the right hand direction, the left hand helical load surfaces 6 engage, the tangential contact length "C" of engagement decreases and the relative axial spacing "Z" (axial stroke) between the drive and idler cams increases until an extreme position is reached, further rotation causing the apexes to move past each other. Since the cam pair must also transmit the load, the extreme position occurs in practice when the contact length is not sufficient to take up the necessary load to allow the total displacement represented by the vector R shown in the figure, where the axial component of R is equal to Z, i.e. the axial stroke. Referring now to fig. 2B, this same limit is illustrated for the cam assembly 1, which shows a left hand rotation being applied to the driving cam body 2 relative to the follower cam body 3, resulting in the right hand helical load surface 5 being active, where the total displacement is represented by the vector L. The axial travel and load capacity (indicated by dimensions Z and C in fig. 2A and 2B, respectively) of such a bi-directional rotating single-cam pair is therefore limited, particularly when combined with other competing design variables, such as preferred pitch or helix angles for controlling left-hand and right-hand directional actuation, as is evident by comparing the cam pairs 4 in fig. 2A and 2B in the case of right-hand and left-hand rotation, respectively. While this single cam pair arrangement providing axial travel in relation to applied relative bi-directional rotation provides substantial utility, in some applications greater travel and load capacity is also desirable.

It is an object of the present invention to provide a device to reduce or effectively eliminate this limitation of the inherent operating range and capacity of a bidirectional single cam pair, and therefore, such a device may be adapted for use with any linkage referred to as a "cam" in table 1 of PCT CA 2006/00710. Referring now to fig. 3, the improved cam structure of the present invention (also shown in schematic two-dimensional pictorial form, wherein the axial and tangential directions are respectively shown as ordinate and abscissa) provides a triple cam assembly 10 having a driving cam body 12, a follower cam body 13, and at least one intermediate cam body 14 to act between the driving cam body 12 and the follower cam body 13; the triple cam assembly 10 is therefore referred to as a triple cam configuration. A pair of drive cams 15 is provided to act between the drive and intermediate cams 12 and 14 and a pair of driven cams 16 is provided to act between the intermediate and driven cams 14 and 13. The pair of drive cams 15 consists of mating stop dogs 17, the mating stop dogs 17 being defined by mating dog stop surfaces 18 of a relatively steep helix angle (shown here as vertical) and mating helical dog ramp surfaces 19 of a relatively shallow left hand helix angle, wherein the mating helical dog ramp surfaces 19 also continue to act with mating load threads 20. The driven cam pair 16 is comprised of mating load ramps 21, the mating load ramps 21 being defined by a relatively steep helix angle mating sloped stop surface 22 (shown here as vertical) and a right hand mating helical load sloped surface 23, shown here as having a moderate helix angle (similar to the helix angle of the right hand helical load surface 5 described for the cam pair 4 of fig. 1).

Referring now to fig. 4A, the triple cam assembly 10 is shown imparting a certain right hand direction rotation causing relative displacement of the drive cam pair 15 initially to cause disengagement of the stop surfaces 18 and, upon sufficient rotation, also the stop inclined surfaces 19 so that the load is fully carried by the mating load threads 20 within the displacement or range represented by vector R. It is now apparent that in the case of right hand rotation, the axial travel and load capacity of the load cam pair 15 is not limited to the available contact length of the helical stop inclined surface 19, but is limited only by the load thread 20, which load thread 20 can be readily configured to provide sufficient engagement length and strength to provide virtually infinite axial travel for sufficient strength, effectively eliminating these limitations for design purposes. In fact, the stopper sloping surface 19 is redundant and does not need to engage at all.

Still referring to fig. 4A, the helix angle of the load ramp 21 and the sloped stop surface 22 defining the driven cam pair 16 is selected relative to the helix angle of the load threads 20, and other variables such as the coefficient of friction will be apparent to those skilled in the art such that no displacement of the driven cam pair 16 occurs under either an advancing or retracting right hand rotation.

Referring now to fig. 4B, the cam assembly 10 is shown imparting left-hand rotation to the driving cam body 12 relative to the follower cam body 13. In this example, the driven cam pair 16 acts and functions in a similar manner to that already described with respect to the drive cam pair 15, with the load ramp spiraling in the opposite direction. Application of a left hand rotation to the drive cam body 12 causes the inclined stop surfaces 22 to separate and the associated sliding contact on the helical load surfaces 23 causes the intermediate cam body 14 and the drive cam body 12 to move axially upwardly relative to the driven cam body 13, providing displacement within the range indicated by the vector L. The axial and left-hand torque loads carried by the tri-cam assembly 10 are reacted by the drive cam pair 15, wherein by selecting the helix angle and position on the contacting dog stop surfaces 18, the stop dogs 17 can be arranged to control the manner in which the loads are reacted by the drive cam pair 15, for controlling stress and preventing the tendency of torsional loads to thread the intermediate cam body 14 onto the drive cam body 12 due to the connection of the intermediate cam body 14 and the drive cam body 12 by the load threads 20, i.e., thread friction locking in the form of nuts and bolts. Also, similar to the behavior already described for right hand rotation, the helix angle of the load ramp 21 is selected relative to the helix angle of the load threads 20 so that the drive cam pair 15 is not displaced by either advancing or retracting left hand rotation.

As is now apparent, the three-cam assembly 10 provides two cam pairs (drive cam pair 15 and driven cam pair 16): in the case of rotation in the right-hand direction, the first cam pair is active and provides axial travel, while the second cam pair is stationary; and in the case of left hand rotation, the second cam pair is active and provides axial travel, while the first cam pair is stationary.

Comparing the displacement vectors R & L between fig. 2A &2B and 4A and 4B respectively, it is illustrated that with a three-cam configuration 10, the driving and driven cam pairs 15 and 16 (fig. 4A & B) can achieve a greater axial stroke in both right-hand and left-hand rotation than with a single two-way cam pair 4 (fig. 2A & B) for comparable geometric parameters.

Referring again to fig. 4B, assuming load threads 20 are employed in the drive cam pair 15 as disclosed above, it is now apparent that load threads may be provided to act in conjunction with a mating helical load surface 23 to increase stroke and load capacity; in certain applications that may occur with a tubular running tool, however, it is advantageous to allow free separation of the driving and driven cam bodies 12 and 13, which is allowed in the configuration shown in fig. 4C, where the intermediate cam body 14 remains engaged to the driving cam body 12 by the load threads 20, but not so engaged to the driven cam body 13 to allow free separation thereof, which may be required in order to ensure clamp actuation with axial loads applied without simultaneous rotation when the three-cam assembly 10 is used in the base (configuration 1) configuration of a clamping tool as shown in fig. 1.

As an intermediate structure (not shown), when load threads for connecting the driven cam body 13 and the intermediate cam body 14 are required, a certain degree of similar freedom for axial separation is also required, and the load threads may be provided with a large thread clearance (backlash). It will be apparent to those skilled in the art that for a single thread, this clearance is limited only by the pitch minus the required thread thickness so that a large free axial spacing can be achieved for applications that can accommodate relatively larger pitches, i.e., for applications that do not require a shallow (low) helix angle.

As an additional intermediate structure (not shown), the two cam pairs may be arranged such that the stopper inclined surface is continuous with the load thread (with little clearance) and thus referred to as a four cam structure (not shown). The four-cam arrangement is provided with a fourth cam member that is constrained to allow axial movement but not rotational movement relative to the idler cam and is rigidly connected to the jaw assembly such that upon release of the latch, the cam assembly maintains the ability to move freely axially to engage the workpiece under the biasing load. This arrangement is beneficial if a greater stroke is required than can be accommodated on a three-cam arrangement, particularly as limited by the driven cam pair arrangement.

Referring again to fig. 4B, it can be seen that the sum of the axial height and strength capability of the stop dogs 17 is related to the pitch or helix angle selected for the mating load threads 20 (and similarly the dog inclined surfaces 19) so that it is more difficult to ensure sufficient strength to react left hand torsional loads for applications where a shallow thread helix angle is advantageous, which is achieved by the stop dogs 17 having an associated smaller axial height. For these applications, it is another object of the present invention to provide an apparatus that overcomes this limitation by replacing the intermediate cam body 14 in the tri-cam assembly 10 with an intermediate cam assembly 30 that acts between the driving cam body 12 and the driven cam body 13, reference now being made to fig. 5A. The intermediate cam assembly 30 is comprised of complementary stop dog advance rings 31 and intermediate cam tubes 32, wherein a pair of stop dog advance cams 33 are provided to act between the stop dog rings 31 and the intermediate cam tubes 32. The dog advance cam pair 33 has an advance ramp surface 34 and an advance catch surface 35. In general, the intermediate cam assembly 30 functions in the same manner as the intermediate cam 14 in both right-hand and left-hand rotation applications, and this has been described for the three cam assembly 10 with respect to fig. 4A and 4B. Now comparing fig. 4B and 5A, the role of the dog advance ring 31 in a left hand torque application is evident, wherein the left hand torque causes the dog advance ring 31 to move up the advance ramp surface 34, fully engaging the dog stop surfaces 18, so that the engagement height of the dog stop surfaces 18 is thus set greater when the dog advance ring structure is used. It will also be apparent that the helix angle of the advance ramp surfaces is selected in combination with the helix angle of the stop surfaces 18 to induce full engagement of the stop surfaces 18 as shown in the left hand rotation application and, as such, the engagement length of the advance ramp surfaces 34 is relatedly provided with sufficient strength to support the loads reacted through the stop surfaces 18. Referring now to fig. 5B, which shows the three-cam assembly 30 in a moderate right-hand direction rotation application, the stop dog advance ring 31 is shown fully slid under the advance ramp surface 34 (with the cam pair 33 in the fully retracted position), which can be moved by being variously induced as follows: previous contact with the dog sloped surface 19 under a right hand direction rotational application (where the helix angle of the dog sloped surface 19 is selected in combination with the helix angle of the advance catch surface 34 to guide this movement); gravity; or a biasing spring (not shown) applies a retraction force against the intermediate cam tube 32. In this position, the cam pair 15 is arranged so that the stop surfaces 18 have a degree of overlap which is large enough to "catch" when left hand rotation is applied but "overtly" in an additional right hand direction rotation application, resulting in additional axial travel under the constraint of the load thread 20 as shown in FIG. 5C.

Referring now to fig. 4C, in certain applications it is desirable to constrain the allowed free axial spacing between the driving and driven cam bodies 12 and 13 by providing a latch, particularly for supporting the insertion and removal of a fully mechanical gripping tool as described in PCT CA 2006/00710. It is therefore another object of the present invention to provide a latch operating with a triple cam configuration supporting the locking of the driving cam body 12 to the driven cam body 13, as schematically illustrated in fig. 6A, wherein the latch 40 is shown in two-dimensional representation with the triple cam 10, wherein the radial plane of appearance of the features of the latch 40 is generally different from the radial plane of appearance of the features of the triple cam 10. The locking ring 41 is a generally tubular body that mates with the driven cam body 13 and is coaxially mounted on the driven cam body 13, the locking ring 41 having a right-hand helical groove 42, and a mating locking tab 43 disposed within the helical groove 42, wherein the locking tab 43 is rigidly connected to the driven cam body 13, the arrangement constraining the locking ring 41 to move only between axially extended and retracted positions relative to the driven cam body 13, the travel of the latch being defined along a helical path defined by the length of the helical groove 42 selected relative to the length of the locking tab 43. A pair of latch cams 47 is provided to act between the locking ring 41 and the drive cam body 12 and is defined by a generally mating contoured latch hook 44, the height of the latch hook 44 being selected to be slightly less than the selected latch stroke, and the latch hook 44 having a rear surface 45. The locking hooks 44 are shown in their engaged position in fig. 6A and are therefore arranged to prevent axial separation of the driving cam body 12 and the driven cam body 13, wherein axial loads that might otherwise act to separate are reacted from the driving cam body 12 through the locking hooks 44 to the locking ring 41 and to the locking splines 43 constrained by the helical grooves 42, and from the locking splines 43 to the driven cam body 13 to which the locking splines 43 are attached. However, in a right-hand direction rotation application, referring to FIG. 6B, the locking hook 44 tends to disengage and the locking ring 41 is allowed to freely retract by the key 43 in the right-hand helical groove 42, wherein retraction may be induced in various forms as follows: gravity; a biasing spring 46 acting between the lock ring 41 and the driven cam body 13; or with contact of the hook rear surface 45 after sufficient rotation, the helix angle of the mating hook rear surface 45 is selected relative to the helix angle of the flutes 42 to induce the retractive force. In a left hand rotation, with the cam pair 16 mated as shown in fig. 6B, i.e., no axial spacing, sufficient engagement of the latch hook 44 is provided to re-lock the hook 44. However, if the drive cam body 12 is first raised, resulting in an axial spacing sufficient to prevent engagement of the shackle 44, and then left hand rotation is applied, referring now to fig. 6C, re-locking is prevented and the cam pair 16 acts to cause axial movement.

As illustrated and described with respect to fig. 6A through 6C, the cam assembly operating sequence from the locked position can be described in the following two steps:

1. putting down tool (put into work)

2. To the right (disengaging the latch and engaging the drive cam pair)

Wherein in order to uncouple (join) by engaging the pair of driven cams with the present tool, two further steps are required:

3. pick-up tool

4. To left (joint driven cam pair)

The operating procedure for disengaging the tool from the workpiece is also very simple and requires two or three steps from assembling or disassembling the bevel, as follows:

1. setting-down tool

2. To the left (retract clamp assembly and engage latch)

Wherein, in order to lock the tool from the idler cam, an additional step is required of:

1a. screw to the right to engage the drive cam pair and then continue to step 1.

Because of the simple operating procedure, sufficient left-hand torque may be unexpectedly or unexpectedly induced while applying rotation and compression on the tool to engage the latch, and if these conditions occur frequently enough, an unacceptable risk of unintended locking and thus disengagement of the clamp assembly from the workpiece may occur. In these applications, it may also be desirable to prevent inadvertent engagement of the latch when it is desired to constrain the allowed free axial spacing between the driving and driven cam bodies by providing the latch, particularly to support insertion and removal of a fully mechanical gripping tool. To achieve this object, it is a further object of the present invention to provide a latch mechanism that operates in conjunction with the three-cam and latch arrangement of fig. 4 and 6A-6C, respectively. Another preferred embodiment of the invention is illustrated in a two-dimensional schematic and described with respect to fig. 7A to 7F. This embodiment is an integral internal mechanical lock designed to introduce a locking function in the cam assembly of fig. 6A-6C. The operating sequence of the cam assembly equipped with the lock can be described in the following six steps:

1. putting down tool (put into work)

2. To the right (disengaging lock bolt)

3. Pick-up tool (unlocking hook)

4. To left (joint driven cam pair)

5. Put down tool (compression spring)

6. To the right (joint lock, joint driving cam pair, and clamping workpiece)

When additional steps are required to disconnect the coupling, the following is performed:

7. to the left (engage the driven cam pair and grab the workpiece)

The operating procedure for disengaging the lock and locking the tool in the assembled position further comprises the steps of:

1. setting-down tool (guarantee joint drive cam pair)

2. To the left (break away the cage and unlock the tool)

3. Pick-up tool (allowing latch to bounce)

4. To the right (returning to the driving cam pair)

5. Setting-down tool (set-down to engage driving cam pair)

6. To the left (retracting the clamp assembly and locking the tool)

If starting from the engagement of the driven-cam pair, an additional step is required, as follows:

1a. to the right to engage the pair of drive cams and then continue to step 1.

As is evident from the above description of the procedure, the additional step reduces the risk of accidental disengagement by increasing the operational complexity.

Referring now to fig. 7A, a three-cam configuration with an integral mechanical latch is shown in schematic two-dimensional diagrammatic form, with the latch shown engaged. The tri-cam assembly with lock has a driving cam body 12, a follower cam body 13, an intermediate cam body 14, and a latch 40. A pair of latch cams 47 is provided for acting between the latch body 41 and the drive cam body 12 and is defined by a substantially mating contoured latch hook 44. The latch hook profile (profile)45 of the latch body 41 includes a latch stop 61 on a top surface 62, and the latch hook profile 45 of the drive cam body 12 has a generally mating latch stop slot 63 on a bottom surface 64 and a latch stop slot on a top surface 69. The angle of the lock stop surfaces 65 and 66, in combination with the angle of the lock stop slot surfaces 67 and 68 and the geometry of the keyway 42, are selected to facilitate engagement of the lock, disengagement of the lock and removal of the latch body during assembly. The keyway 42 of the latch body 41 and the key 43 rigidly attached to the idler cam 13 have a pair of latch surfaces 70 consisting of generally mating locking surfaces 71 and 72. The angles of latch surfaces 71 and 72 are selected in combination with the angle of load threads 20 to eliminate accidental release of the latch due to vibration and to reduce uncertainty in the position of latch stop 61 engaging the tip of latch hook profile 45 of drive cam body 12. The idler cam 13 has a limited travel, pre-stressed compression spring 73, but when the latch 40 is disengaged, the biasing spring 46 drives the surface 74 and the latch body 41 contacts the spring stop 75. The spring rate and pre-stress of the compression spring 73 are selected in combination with the spring rate and pre-stress of the biasing spring 46 so that the spring 73 is not compressed beyond the initial pre-stressed position under the load of the biasing spring 46 and any additional loads including the weight of the components.

Referring now to fig. 7B, the cam assembly of fig. 7A is shown in schematic two-dimensional diagrammatic form with the latch disengaged and the latch hook surfaces in face-to-face contact, with the compression spring 73 remaining fully extended and in contact with the latch body 41 such that the hook surfaces of the latch hook profiles 45 overlap and slidingly engage. The key 43 is placed within the helical portion 77 of the keyway 42 so that a right hand rotation will cause the shackle profile to disengage and a left hand rotation will cause the latch body 41 to helically slide over the keyway 42 and engage the shackle of the shackle profile 45, placing the assembly in the position shown in fig. 7A by extending the biasing spring 46.

Referring now to fig. 7C, the cam assembly of fig. 7A is schematically illustrated in schematic two-dimensional diagrammatic form showing the latches disengaged and in a left-hand torque application, the helical load ramp surfaces 23 of the idler cam pair 16 engaged, and the helical stop ramp surfaces 19 of the drive cam pair 15 engaged with the mating stop surfaces 18.

Referring now to FIG. 7D, the cam assembly of FIG. 7A is schematically illustrated in a schematic two-dimensional representation, shown under a compressive load after the idler cam pair 16 is engaged. All mating surfaces of the drive cam pair 15 and the driven cam pair 16 are engaged and the cam assembly 10 is under compression. Surface 74 of latch body 41 engages spring stop 75 and compression spring 73 is compressed beyond the pre-stressed position. The key 43 is disposed within the helical portion 77 of the keyway 42. The lock stop 61 engages in the lock stop groove 63. Application of a right hand rotation to the drive cam will move the latch body 41 into the locked position by engaging surfaces 71 and 72 of the latch pair 70.

Referring now to fig. 7E, the cam assembly of fig. 7A is shown schematically in schematic two-dimensional illustration showing the latch 40 locked, while the drive cam 12 and latch body 41 are placed in an unlocked position by application of left-hand rotation relative to the idler cam 13. The tip of the latch profile 45 of the drive cam 12 is slidingly engaged on the surface 65 of the lock stop 61 and left hand rotation along the drive cam pitch will result in similar movement of the latch body 41 relative to the idler cam 13 and intermediate cam 14, whereupon positive axial movement of the drive cam 12 will result in the key 43 moving from the locking portion 76 of the keyway 42 into the helical portion 77.

Reference is now made to fig. 7F, which schematically illustrates the cam assembly of fig. 7A in a two-dimensional pictorial form, shown locked and imparting a right-hand direction rotation on the drive cam 12 relative to the idler cam 13 and the intermediate cam 14. As shown, it will be appreciated that in the locked position, the drive and driven cam pairs 15, 16 may be active.

It is now apparent that the overall mechanical lock arrangement of the present invention is well suited to prevent accidental locking of the three-cam arrangement of the present invention, since the likelihood of accidental occurrence of the additional steps required in the locking sequence is reduced.

It should be understood that the latch may be locked by a number of means including, but not limited to, mechanical and hydraulic.

Other structures for locking between the driving cam body 12 and the driven cam body 13 may be similarly provided. One such arrangement (not shown) biases locking ring 41 in the normally extended position. Under a right hand rotation, the locking ring 41 tends to push the locking hook 44 out of engagement. The shackle is shaped and distributed to prevent partial engagement in an intermediate rotational position (within one revolution or less) which would prevent left hand rotation; without this resistance, left hand rotation would occur because the pitch of the load threads 20 and the selected height of the shackle 44 would allow left hand rotation.

It is now apparent that the locking three-cam arrangement of the present invention is well suited to support the provision of additional radial travel, which may be advantageous for an external gripping tool such as that shown in fig. 1, where, for example, it is desirable to typically grip a connecting tube having a range of sizes below the connector (coupling).

Three-cam structure of internal clamping (internal clamp) tubular running tool

Referring to fig. 8-13B, a preferred embodiment of an improved gripping tool, referred to herein as an "internal clamp tubular running tool having a three-cam configuration", is now described. Referring now to FIG. 8, there is shown an external view of a preferred embodiment tubular running tool, generally designated by the reference numeral 100 and shown in a locked configuration, having a body assembly 110 and a clamp element assembly 120.

Referring now to FIG. 9, a cross-sectional view of the tubular running tool 100 is shown in a locked configuration, positioned within and co-radially (co-radially) with the proximal end 101 of the workpiece 102. The tubular running tool 100 is arranged to be connected at its upper end 105 to the distal end of a top drive drill spindle or a column part of such a drive that may be attached thereto, by means of a load adapter 112 (not shown in the figures) integrated to the mandrel 130, so that the mandrel 130 serves as the main body of the running tool 100. The load adapter 112 is generally axisymmetric and made of a suitably stiff material. It has an upper end 121, the upper end 121 being provided with an internal thread 122 adapted to be sealingly connected to the drill shaft of the top drive, an internal through hole 123 continuous with the mandrel 130.

Still referring to FIG. 9, the tubular running tool 100 has a body assembly 110, the body assembly 110 being comprised of an elongated generally cylindrical mandrel 130, the mandrel 130 having an upper end 131, a lower end 132 having an outer frustoconical surface 133, and an internal bore 136. The mandrel 130 has a body thread (body thread)134 and a key element 135 at an upper end 131. The tubular running tool 100 is provided with a locking ring 140, the locking ring 140 having a key portion 142 at a lower end 141. Locking ring 140 is shown here as having a generally tubular outer sleeve 184 that is positioned outside of and mates with load adapter 112, wherein outer sleeve 184 is provided to protect load adapter 112 from damage by pliers. The mandrel 130 supports an inner axially actuated clamp assembly 120, the clamp assembly 120 having an elongated and generally cylindrical lower end 109 that is inserted and coaxially located within the upper abutment end 101 of the tubular workpiece 102. The clamp assembly 120 is comprised of a cage 144, the cage 144 having an upper end 145 and a lower end 146, and having a threaded member 147 at the lower end 146, having an axial retention slot 148, and a plurality of radially oriented windows 149 arranged around the circumference at the lower end 146, with the jaws 160 disposed within the windows 149. The generally elongated pawl 160 has an upper end 161, a lower end 162, an inner surface 163, an outer clamp surface 164 and parallel side surfaces (not shown), the pawl 160 having a plurality of frustoconical contact surfaces 166 on the inner surface 163 that engage a mating frustoconical surface 133 of the spindle 130 to form the sliding interface 114 to provide radial travel to the pawl 160 in response to axial actuation.

Still referring to fig. 9, the tubular running tool 100 has bi-directional rotation to effect axial stroke actuation of the tri-cam locking linkage 200, the linkage 200 generally being provided with a tri-cam configuration and including a driving cam body 220, a driven cam body 260 and an intermediate cam body 240. The linkage 200 acts between the spindle 130 and the clamp assembly 120 and is contained within a housing assembly 180, the housing assembly 180 including driven and drive cam housings 181 and 182. The three-cam locking linkage 200 functions and is generally arranged as previously described with respect to the schematic illustrations 3-4C and 6A-6C.

Referring now to fig. 10A, the linkage 200 is shown in a locked configuration, wherein the assembly is provided with a drive cam body 220 having an upper end 222. Referring to fig. 10B, a cross-sectional view of the tri-cam assembly 200 is shown in a locked configuration, the tri-cam assembly 200 having a drive cam body 220, the drive cam body 220 having a lower end 223, an outer surface 224 and an inner surface 225, and one or more torque lugs 226 (eight shown here) at an upper end 222. The inner surface 225 of the drive cam body 220 has a threaded element 227 at the upper end 222 and a sealing element 228 at the lower end 223. Referring again to FIG. 9, the body threads 134 on the mandrel 130 threadably engage the threaded element 227 on the drive cam body 220, while the sealing element 228 sealingly engages the outer surface of the mandrel 130. The key portion 142 of the locking ring 140 engages a torque transmitting protrusion (not visible in this cross-sectional view, but represented by reference numeral 226 in figure 10B) on the drive cam body 220 and a key element 135 on the spindle 130 so that the drive cam body 220 is structurally and rigidly attached to the spindle 130 and prevented from moving axially and circumferentially relative to the spindle 130. Referring again to fig. 10B, a bottom surface 229 of the drive cam body 220 includes a plurality of latch hooks 230. The outer surface 224 of the drive cam body 220 includes a plurality of load threads 231 at a lower end 223. The load thread 231 is substantially composed of a push thread (push thread) having a load flank (loadflight) 233 and a stab flank (stab flank) 234. The drive cam body 220 has a sealing element 236 on the outer surface 224 at the upper end 222. Referring again to fig. 10A, the drive cam body 220 has a stop surface 232 and a stop ramp surface 237 on the outer surface 224 of the upper end 222 that are located on a downwardly facing shoulder 296.

Still referring to fig. 10A, an intermediate cam body 240 having an upper end 241, a lower end 242, an inner surface (not shown), and an outer surface 244 has one or more stop surfaces 245 (three are shown here) at the upper end 241 that engage the stop surfaces 232 at the upper end 222 of the drive cam body 220 to collectively form a pair of stop surfaces 255. Also at the upper end 241 of the intermediate cam body 240 are one or more (here shown as three) stop inclined surfaces 256 that cooperate and slidably engage the stop inclined surfaces 237 of the drive cam body 220 to collectively form a pair of stop inclined surfaces 257. Still referring to fig. 10B, the intermediate cam body 240 has load threads 246 (shown here as a multiple thread form with a thread lead that matches the helical pitch of the stop sloped surface 256) on an inner surface 243 at an upper end 241, which threads are configured as stab threads having a load flank 247 and a stab flank 248, and that mate with and slidingly engage the load threads 231 of the drive cam body 220 to form a load thread pair 268, which load thread pair 268 in combination with the stop and stop sloped surface pairs 255 and 257 together form a drive cam pair 249. Referring now to fig. 10A, the intermediate cam body 240 has one or more (here shown as six) helical load ramp surfaces 250 disposed radially adjacent and in common with an equal number of stop load surfaces 251 on the lower end 242.

Still referring to fig. 10A, the driven cam body 260 having an upper end 261, a lower end 262 and an outer surface 263 has a plurality of helical load ramp surfaces 265 disposed radially adjacent and in common with a stop load surface 266 on the upper end 261, the helical load ramp surfaces 265 and stop load surfaces 266 of the driven cam body 260 cooperating with and slidably engaging the helical load ramp surfaces 250 and stop load surfaces 251 of the intermediate cam body 240 to collectively form a driven cam pair 267. Referring now to fig. 10B, the driven cam body 260 has one or more torque transmitting projections 269, twelve (12) in this example, on the bottom surface 270 of the lower end 262. Referring now to fig. 9, the torque transfer projections 269 of the driven cam body 260 mate with the torque transfer projections 143 on the upper end 145 of the cage 144 and, in this embodiment, are bolted together at bolt holes 297 (bolts not shown) to structurally and rigidly attach the driven cam body 260 to the cage 144. Still referring to fig. 10B, on the inner surface 264 of the lower end 262 of the follower cam body 260 is a sealing element 273 and an upwardly facing shoulder 274, while on the outer surface 263 of the lower end 262 is a sealing element 275.

Still referring to FIG. 10B, the cam assembly 200 has a lock ring 300 of generally tubular shape having an upper end 301, a lower end 302, and an inner surface 303. Referring now to FIG. 11, showing the assembly of drive cam body 220, lock ring 300 and lock key 290, lock ring 300 has a plurality of helical lock key slots 305 (six shown here) that may be evenly spaced circumferentially on outer surface 304. Keyway 305 has an inner surface 306, a load surface 307, and helical sliding cam surfaces 309 and 310. Inner surface 306 of lock keyway 305 has pin clearance slots 308 that extend to inner surface 303 of lock ring 300. Still referring to fig. 10B, at the lower end 302 of the locking collar 300, on the inner surface 303 is an upwardly facing shoulder 315. At the upper end 301 of lock ring 300, top surface 312 has a plurality of locking hooks 313. The latch hooks 313 on the locking ring 300 cooperate with the latch hooks 230 on the bottom surface 229 of the driving cam body 220 to collectively form a latch hook pair 314, the latch hooks 230 and 313 being selected to prevent relative axial separation of the driven cam body 260 relative to the driving cam body 220 when the latch hook pair 314 is engaged.

Still referring to FIG. 11A, lock ring 300 is assembled with lock key 290 inside lock key slot 305. Referring now to fig. 11B, a partial cutaway view of a partial cam assembly is shown including the follower cam body 260, the catch 300, the lock pin 337, the catch 290, and the spring elements 346 and 349, with the lock pin 337 and the latch tab 338 (not shown in this view) rigidly attached to the follower cam body 260 and extending therethrough to slidably engage the shear pin hole 291 in the catch 290. Referring now to fig. 10A, the radially oriented locking pin 337 and the radially oriented latch protrusion 338, which are not aligned in the same radial plane as the locking pin 337, cooperate to constrain movement of the locking key 290 relative to the driven cam body 260. In this way, the lock ring 300 is constrained such that the amount of helical movement thereof relative to the driven cam body 260 is defined by the relative axial length difference between the lock key 290 and the lock key slot 305, see fig. 11A. Referring to fig. 11B, the inboard end 339 of the lock pin 337 extends through the clearance slot 308 of the lock key slot 305 and slidingly engages the retaining ring pin hole 323 in the retaining ring 320 and cooperatively constrains the movement of the retaining ring 320 relative to the driven cam body 260. Still referring to fig. 11A, because load surface 293 of assembled locking key 290 and load surface 307 of lock ring 300 collectively form load surface pair 315, the locked axial load is transferred from drive cam body 220 (not visible in this view) to lock ring 300 through load surface pair 315. The helical slide cam surfaces 296 and 297 of the catch 290 and the helical cam surfaces 309 and 310 of the catch 300 cooperate to form helical slide cam pairs 317 and 318, respectively, such that the cam pairs 318 or 317, respectively, are engaged when the catch 290 is moved up or down relative to the catch 300. Referring now to FIG. 11C, there is shown a partial assembly comprising drive cam 220, lock ring 300 and catch 290, shown in the initial right hand direction rotation of drive cam 220, lock ring 300 tending to be pushed down to the following position: the hook pairs 314 still overlap slightly to facilitate re-locking under left hand rotation, as described with respect to fig. 6B, but do not interfere in subsequent right hand rotation, resulting in axial travel being constrained by movement along the load threads 231.

Still referring to FIG. 10B, the triple cam assembly 200 may have spring elements 346, in this example, coil springs located inside the check ring 300 and acting in compression between the spring retaining ring 320 and the check ring 300, such that the spring elements 346 typically work in conjunction with gravity and act to bias the check ring 300 in an axially downward position.

Still referring to fig. 9, the three-cam assembly 200 is located inside a cam housing assembly 180, the housing assembly 180 being comprised of an idler cam housing 181 rigidly attached to an idler cam 260 and in sealing engagement with a sealing element 275, and a drive cam housing 182 rigidly attached to a drive cam 220 and in sealing engagement with a sealing element 236, the housing assembly 180 providing a sealed cam cavity 183 allowing pressurized gas to be added to the cavity 183 to act as a spring which, upon disengagement of a latch 295, tends to force the clamp assembly 120 into engagement with the workpiece 102.

Referring now to FIG. 10A, an exterior view of the tri-cam assembly 200 is shown in a locked position with the driving cam body 220, the follower cam body 260 at a minimum axial spacing such that the driving cam pair (not shown), the dog stop surface pair 255 and the dog ramp surface pair 257 of the driving and intermediate cam bodies 220 and 240, respectively, are engaged and the follower cam pair 267 of the intermediate and follower cam bodies 240 and 260, respectively, are engaged. Referring now to FIG. 10B, which shows a cross-sectional view of triple cam assembly 200 in the locked configuration providing locking ring 300, latch 295 is located inside triple cam assembly 200 and is disposed radially therewith, and has been described previously with respect to FIGS. 6A-6C. The latch 295 provides a means for preventing the free axial separation of the driving and driven cam bodies 220 and 260, respectively.

Referring now to FIG. 12A, an exterior view of the tri-cam assembly 200 is shown with the drive cam pair 249 engaged and the drive cam body 220 having rotated two-thirds of a turn relative to the idler cam body 260 and the intermediate cam body 240 in a right-hand torque application. The pair of stop load surfaces 268 and the pair of driven cams 267 are engaged to react axial and torque loads between the driven and intermediate cam bodies 260 and 240, respectively. Referring now to FIG. 12B, a cross-sectional view of the triple cam assembly 200 is shown in a right-hand torque application as previously described with respect to FIG. 12A. Latch 295 has been disengaged and shackle 300 is in a downward position as biased by gravity (in this direction) and spring element 346 so that lower end 302 of shackle 300 is engaged on spring element 349. Spring element 349 is a relatively stiff spring, in this example, a stack of Belleville washers consisting of three Belleville washers arranged in parallel and preloaded in compression so that the combined force of the biasing element acting on lock ring 300 is small relative to the preload of spring element 349, as is the position of spring element 349 and thus the axial position of lock ring 300 biased downward. The function of the spring element 349 is to prevent overloading of the latch hook 314 in the event of a compressive load on the triple cam assembly 200 when only a limited pair of latch hooks 314 are engaged. The left hand helical drive cam pair 255, in this example in the form of a six-line American zigzag push thread, allows rotation resulting in an axial stroke of more than one full revolution, which is greater than would be possible with a single pair of bidirectional rotary cams as described in relation to fig. 2A and 2B.

Referring now to fig. 13A, an external view of tri-cam assembly 200 is shown with latches 295 disengaged and tri-cam assembly 200 in a left-handed torque application, with idler cam pair 267 engaged and driving and intermediate cam bodies 220 and 240, respectively, undergoing a relatively small amount of rotation relative to idler cam body 260. The pair of stop surfaces 255 and the pair of helical stop ramp surfaces 257 have engaged to react axial and torque loads between the drive cam body 220 and the intermediate cam body 240. Referring now to FIG. 13B, a cross-sectional view of triple cam assembly 200 is shown with latch 295 disengaged and triple cam assembly 200 in a left-hand torque application with lock ring 300 in a downward position such that lower end 302 of lock ring 300 is in contact with spring element 349. To move the tri-cam assembly 200 from the locked configuration as previously described with respect to fig. 12A and 12B to the configuration shown in fig. 13A and 13B, it is necessary to first apply a right-hand torque to disengage the latch 295 and then apply sufficient axial displacement to move the latch hooks 314 out of the overlapping (see fig. 11C) range so that the idler cam pairs 267 will engage without interference from the latch hooks 314 under the application of a left-hand torque. Still referring to fig. 9, the axial travel required to move the lock hook 314 out of engagement is set to fall within the dead travel of the tool, i.e., the axial travel required prior to possible engagement of the clamp assembly 120 and the workpiece 102. The right hand helical driven cam pair 267, in this example a six-line ramp, provides axial travel and torque loading under left hand rotation at some intermediate cam angle and also provides free axial separation of the intermediate and driven cam bodies 240 and 260, respectively, if the latch 295 is disengaged, allowing axial travel of the clamping tool 100 to act on the clamped workpiece 102 under the applied axial load independent of the rotation.

In this patent application, the word "comprising" is used in a non-limiting sense to mean that something following the word is included, but nothing not specifically mentioned is excluded. The indefinite article "a" or "an" does not exclude the possibility that more than one of the element is present, unless the context clearly requires one and only one of the elements.

It will be apparent to those skilled in the art that modifications may be made to the illustrated embodiments without departing from the spirit and scope of the invention as defined in the following claims.

Claims (8)

1. In a gripping tool having a gripper surface carried by a movable gripper element and a linkage to move the gripper surface radially from a retracted position to an extended position, the improvement comprising:

the linkage includes a three-cam linkage and a further cam linkage, the three-cam linkage comprising:

a drive cam body receiving a rotational input tending to advance a rotational motion;

an intermediate cam body that solely receives rotational input from the drive cam body;

a driven cam body that solely receives a rotational input from the intermediate cam body;

a pair of drive cams acting between the drive cam body and an intermediate cam body such that rotational input from the drive cam body is transmitted through the pair of drive cams to the intermediate cam body;

a pair of driven cams acting between the intermediate cam body and the driven cam body such that rotational input from the intermediate cam body is transmitted to the driven cam body through the pair of driven cams,

wherein the cam pair supports actuation of axial travel by bi-directional rotation and the additional cam linkage relates radial travel to axial travel of the clamp surface.

2. The improvement of claim 1, wherein the pair of drive cams is arranged to be active only so that axial travel is related to rotation in a first direction of rotation, and the pair of driven cams is arranged to be active only so that axial travel is related to rotation in a second direction of rotation, the splitting of bi-directional rotary actuation onto the two cam pairs facilitating greater axial travel and associated radial travel for the clamp surface than if a single cam pair were used in a bi-directional rotary actuated linkage.

3. The improvement of claim 1, wherein the triple cam linkage is provided with a latch that when engaged prevents axial stroke actuation of the triple cam linkage.

4. The improvement of claim 3, wherein the three-cam linkage is provided with a mechanical lock that prevents the latch from engaging when the mechanical lock is actuated.

5. The improvement of claim 1, wherein the gripping tool has a load adapter rigidly secured to the drive cam body.

6. The improvement of claim 5, wherein the pair of drive cams is arranged to be active only so that axial travel is related to rotation in a first direction of rotation, and the pair of driven cams is arranged to be active only so that axial travel is related to rotation in a second direction of rotation, the splitting of bi-directional rotary actuation onto the two cam pairs facilitating greater axial travel and associated radial travel for the clamp surface than if a single cam pair were used in a bi-directional rotary actuated linkage.

7. The improvement of claim 5, wherein the triple cam linkage is provided with a latch that when engaged prevents axial stroke actuation of the triple cam linkage.

8. The improvement of claim 7, wherein the three-cam linkage is provided with a mechanical lock that prevents the latch from engaging when the mechanical lock is actuated.