GB2265647A - A drive coupling device for a longitudinally displaceable rotatable drive member - Google Patents

Abstract

A drive coupling device for a longitudinally displaceable rotatable drive member (14) having screw threaded connector means for connecting the member (14) to a correspondingly threaded part (11a) of a driven member (11) comprises a longitudinally slidable collar (37) surrounding the driven member (14) and fixed for rotation therewith, the collar being displaceable between a retracted position as shown in which it leaves the said screw threaded portion exposed, and an advanced position in which ft at least partially surrounds the said screw threaded portion (14b) for cooperative engagement with a driven member (11) screw threadedly engaged on the drive member (14). This allows a threaded coupling 11b, 12a to be unscrewed by the drive member without unscrewing the joint between drive member 14 and driven member 11. <IMAGE>

Description

A DRIVE COUPLING DEVICE FOR A LQNGITUDINALLY DISPLACEABLE ROT TABLE DRIVE MEMBER The present invention relates generally to a drive coupling device for a longitudinally displaceable rotatable drive member.

The present invention relates particularly, but not exclusively, to a drive coupling device suitable for coupling and driving the elements of a string of longitudinally coupled members, for example, drill rods or tubes for horizontal or vertical drilling. For this purpose, as is known, individual drill rods must be added sequentially to the drive end of the drill string during drilling, or sequentially removed from the drill string as the drill string is withdrawn from the drilled hole.

This involves repeated coupling and uncoupling of a longitudinally reciprocable rotatable drive member and, since screw coupling is the most practical, requires not only that adjacent drill rods or tubes be screwed together for coupling, but also that take drive member and nearest adjacent drill rod or tube be screwed together to couple the drive member to the drill string for effecting advancing linear motion and rotation about the longitudinal axis of the drill string.In addition to this, upon retraction, it is necessary to be able to unscrew two adjacent screwed couplings and to be able selectively to turn the drive member in a first direction to screw up or tighten the couplings, which presents no particular problems of selection, but also to unscrew either the drive member front the nearest adjacent drill rod or the next adjacent drill rod from the next drill rod in the string (without, by this action, releasing the drive member from the nearest adjacent drill rod) without incurring the risk that the transmission of torque upon reverse rotation may be transmitted through two or more drill members to effect separation of two adjacent members in the string downstream from the said first two (namely the nearest adjacent and next adjacent said drill members) which could plainly result in drill member recovery problems due to inaccessibility.

The drill coupling of the present invention finds equal utility in association with vertical or horizontal drilling apparatus. The latter is described, for example, in British Patent Application No 9118575.1 which describes apparatus for forming an elongate subterranean hole by driving a drill string of connectable rods generally parallel to and beneath the surface of the ground either from a preliminarily formed hole or by first introducing the drill string at an angle in a socalled "surface launch" technique. As described in that earlier specification, the leading drill rod has a drill bit or head having an inclined face and the drill rods of the drill string are continuously rotated whilst being advanced in order to maintain the screw couplings between adjacent drill rods.The position of the drill head or bit is sensed by remote sensing means on the surface, and any deflection from the intended line, for example by contact with harder ground, stones or the like, is corrected by temporarily stopping the rotation with the drill head in a fixed angular orientation such that the said inclined face of the drill head causes a degree of lateral deflection thereof upon forward movement.

According to one aspect of the present invention, therefore, there is provided a drive coupling suitable for use in apparatus for drilling holes by advancing a plurality of longitudinally coupled elongate members by mears of a reciprocating drive member, in which relative rotation in one direction about the longitudinal axis of the said member occurs to release the coupling, and there are provided means for selectively transmitting torque between adjacent said members whereby to allow rotation in both directions without effecting such release.

According to a second aspect of the present invention apparatus for coupling and uncoupling individual members of a string of longitudinally coupled drive transmitting drive rod members may be provided with drive coupling means as defined hereinabove.

A second aspect of the present invention provides a drive coupling for a longitudinally displaceable rotatable drive member having screw threaded connector means for connecting the member to a correspondingly threaded part of a driven member, comprising a collar surrounding the said drive member and engaged thereon so as to be longitudinally displaceable with respect thereto and fixed for rotation therewith, the said collar being displaceable longitudinally of the said drive member between a retracted position in which it leaves the said screw threaded portion exposed and an advanced position in which it at least partially surrounds the said screw threaded portion for cooperative engagement with a driven member screw threadedly engaged on the drive member whereby to permit bi-directional transmission of rotation between the drive member and the driven member without causing relative unscrewing thereof.

In a preferred embodiment of the invention the said longitudinally displaceable rotatable drive member has a generally circular cross section with at least one flat surface at least adjacent one end thereof, by which the said longitudinally displaceable collar is fixed for rotation.

The rotary coupling between the said longitudinally displaceable collar and the said rotatable drive member may be effected by form engagement between a part of the rotatable drive member having a prismatic cross section and a correspondingly shaped prismatic aperture passing through the said collar.

As an example of such form coupling, at least the said part of the said drive member may have a square or hexagonal cross section and the said aperture in the collar may have a correspondingly shaped cross section throughout.

Alternatively, at least part of the said rotatable drive member may have a plurality of longitudinally extending splines engaged in a correspondingly splined aperture passing through the said collar.

As outlined above, the said longitudinally displaceable rotatable member may be a drive member for driving a drive string of rods or tubes, said drive member being linearly reciprocable by drive member reciprocation means.

Preferably there are further provided means for automatically effecting relative displacement of the said collar and the said drive member in the vicinity of one end of the range of reciprocating movement of the said drive member.

Apparatus for advancing a drill string, of which the drive coupling of the present invention may form part, may be further provided with drill member clamp means operable to clamp that drill member to which the drive member is connected, against longitudinal and rotary motion. For consistency, the drill member to which the drive member is connected, about to be connected, or just released from will be referred to as the "nearest" adjacent drill member, and a drill member to which the said first drill member is itself connected, on the end remote from the drive member, will be referred to as the second or next adjacent drill member. Preferably there are two such clamp means longitudinally spaced along the path of the drill string and positioned such that the nearest adjacent drill member and the said next adjacent drill member to which the said nearest adjacent drill member is connectable can both be clamped. The relative positions of the said two clamps are preferably chosen such that the junction between the said nearest adjacent drill member and the said next adjacent drill member can be located between the said two clamps.

Of the said two clamps, that nearest the drive member is preferably pivoted in such a way as to turn a drill member clamped thereby between a first position longitudinally aligned with the said drive member and a second position inclined with respect to the longitudinal direction of the said drive member.

Control of the advancing and rotary movement of the said drive member, and of the clamps and other parts of the apparatus, may be achieved by means of a bank of individual control valves for selective operation of the moveable parts. Alternatively, there may be provided sensors for detecting the relative positions of the moveable parts, and control valves operable to perform predetermined sequences of operations which are undertaken repeatedly when advancing or retracting the drill string. Such sequences of operations will be described hereinbelow in more detail with reference to the specific embodiment illustrated in the drawings.

One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of the major components of a drill advancing apparatus incorporating the drill coupling means of the present invention; Figure 2A is a schematic partly sectional view taken on the line II-II of Figure 1; Figure 2B is a schematic partly sectional view similar to Figure 2A, showing an alternative embodiment; Figure 3 is a schematic side view of the embodiment of Figure 1 shown in a first working position; Figure 4 is a side view similar to that of Figure 3, showing the embodiment in a second working position; and Figure 5 is a side view of the embodiment showing the components in a third working position.

Referring now to the drawings the apparatus shown in illustrated in a highly schematic manner in order to identify only the relative positions and movements of the principal components necessary for understanding the invention. It is understood that in this context supporting frameworks, power supplies, ducting and piping for hydraulic fluid and the like, all of which are well within the purview of the ordinary man skilled in the art to provide in deriving a complete picture of the invention are not shown in order to simplify and for the present description as the novel aspects of the invention. The apparatus illustrated is suitable for driving a horizontal drill string comprising a plurality of drill members or rods indicated 11, 12, 13 in Figure 1.Each drill rod has a generally circular cross section with a short flat face lia, 12a, 13a adjacent one end of the rod. In an alternative embodiment (not illustrated) the flat may be formed over the whole length of the rod.

As another alternative a rod with a hexagonal section may be used as illustrated in Figure 2B. Each drill rod has a screw threaded portion at one end: only one of these is visible in Figure 1, belonging to the rod 11 and identified with the reference lib. In its opposite end from that having the screw threaded portion each rod has a correspondingly threaded axial socket (not shown in any of the drawings) into which a threaded spigot of an adjacent drill rod may be screwed. In the embodiment illustrated it is necessary to align the flats of the drill rods by visual observation before engagement with the other can take place. In another embodiment (not illustrated) the start points of the screw threads are so arranged that when connected to adjacent drill rods are locked with their flats faces substantially flush with one another.

The drill rod 11, which identified hereinabove with "first" or next adjacent drill rod is shown connected to a reciprocable drive member 14, also having a flat face 14a, which is born in a thrust bearing 15 and driven to rotate by a hydraulic or electric motor 16 carried by a frame 17 (shown only schematically in Figure 1) displaceable, parallel to the length of the drill string, by two double-acting multiple-piston linear hydraulic actuators 18, 19 having one piston rod 20, 21 respectively projecting from the left hand end and connected to the frame 17, and two piston rods 22, 23 and 24, 25 respectively projecting from the right hand end (as viewed in Figure 1) and connected to a fixed frame member 26 (again, shown only schematically in Figure 1).

Extension and retraction of the pistons 20-25 within the cylinders 18, 19 can therefore cause displacement of the movable frame 17 and consequently the motor 16, thrust bearing 15 and drive member 14 over a relatively extended range of linear movement parallel to the length of the drill string and exceeding the length of each individual member 11, 12, 13 by a distance which will be discussed in more detail hereinbelow.

The fixed frame member 26 has an aperture 27 through which the appropriate member of the drill string can pass, and adjacent the fixed member 26 are two clamps 28, 29 selectively operable to lock a drill rod passing therethrough against both rotation and longitudinal displacement. Figure 2 illustrates the structure of the clamp 28 in schematic form, showing it with a lower clamp jaw 30, an upper, movable clamp jaw 31 the position of which is controlled by a hydraulic actuator which can be operated to cause the upper jaw 31 to be lowered into contact with the drill rod located between the jaws whereby to fix this securely, and withdrawn to the position shown in Figure 2 in which the drill rod is free to pass between the jaws and to rotate with respect thereto.The clamp 29 has a similar construction but, as shown in Figures 3, 4 and 5, the clamp 28, which is nearer the drive member 14, also has the additional feature that it is mounted as a whole for turning movement about a pivot axis 33 (for example by mounting it between two parallel plates (not illustrated) secured to the frame 26) about which the clamp 28 is turnable by extension and retraction of a clamp inclination control actuator 34 having a piston rod 35 pivotally connected at 36 to the body of the clamp 28. The purpose of the pivoting arrangement will be described in more detail below.

Over the drive member 14 is fitted a slidable collar 37 having a circumferential groove 38 engaged by two pins 39, 40 carried on respective lateral arms 41, 42 mounted for rotation about a transverse pivot 43. Each of the arms 41, 42 is L-shape, as can be seen in Figures 3 to 5.

Only the arm 42 is visible in the latter figures, in which can be seen a transverse foot portion 44 extending generally at right angles to the main limb of the arm 42.

The pivot axis 43 about which the arms 41, 42 are turnable, is connected to a movable frame member 45 (schematically illustrated in Figures 3 to 5) which is fixed in relation to the thrust bearing 15 and motor 16 so as to be movable therewith upon extension and retraction of the main longitudinal displacement actuators 18, 19.

The connection of the pivot axis 43 to the frame member 45 is achieved by means of a coupling which allows relative movement parallel to the drive member axis between the L-shape arms 41, 42 and the movable frame member 45 itself. This is schematically illustrated in the drawings as a slotted coupling between the pivot axis 43 and a longitudinal slot 48 in a side flange 49 depending from the movable frame member 45. The side flange 49 has an abutment 50 at one end engaged by one end of a compression spring 51 extending between the abutment 50 and the arm 42. This allows the arm 42, and consequently the collar 37, to be displaced with respect to the movable frame member 45 and the drive member 14 as will be explained in more detail below.

Beneath the foot 44 of the arm 42 (and correspondingly beneath the foot of the arm 41, which latter cannot be seen in the drawings) is located a ramp 46, and a resilient biasing member, illustrated as a spring 47, urges the arms 41, 42 to rotate, in a clockwise direction as viewed in Figures 3 to 5, with respect to the movable frame member 45. This, as can be seen in Figure 3, causes the collar 37 to be advanced, with respect to the drive member 14, to a position where it covers the threaded end 14b (see Figure 5) of the drive member 14.

In this advanced position, as can be seen in Figure 3, the collar 37 also covers the adjacent end of the first or next adjacent drill rod 11, engaging the flat lla to transmit rotation from the drive member 14 to the drill rod 11 in either direction of rotation without permitting the screw threaded coupling between them to tighten or release.

As the actuators 18, 19 are extended, to move the motor 16, thrust bearing 15 and drive member 14 to the left as viewed in the drawings, this brings the foot 44 of the lever 42 (and the corresponding foot of the lever 41) into engagement with the ramp 46 causing the level 42 to turn in an anticlockwise direction thereby causing the collar 37 to be displaced, with respect to the drive member 14 to the position illustrated in Figure 4.

The apparatus described hereinabove operates as follows: First, as viewed in Figure 1, the drive member 14 has just been connected by screwing to the first or nearest adjacent drill member 11 and is held against rotation and linear displacement by closure of the clamp 28. At the same time the clamp 29 is closed to hold the next adjacent or second drill member 12 against both rotation and linear displacement. Thereafter the clamp 28 is released and the actuators 18, 19 caused to withdraw either the piston rods 20, 21 or the rods 22-25 (or both) to cause displacement of the drive member 14 to the right to cause the threaded spigot llb to enter the threaded socket in the left hand end of the drill rod 12 such that, by rotation of the motor 16 and therefore of the drive member 14 and the first drill rod 11, this latter is caused to be screwed into the end of the second drill rod 12.Thereafter, upon release of the clamp 29, the actuators 18, 19 are caused to retract further thereby driving the drill string as a whole to the right.

As previously described, the motor 16 is continuously rotated during this motion in order to keep the drill string travelling in a straight line. If deflection of the drill tip is required the motor is held stationary in a particular angular orientation whereby to cause the drill string to be deflected as the inclined face of the drill head or tip engages the ground in a fixed orientation. As it approaches the clamp 28 the collar 37 engages the front faces of the jaws 30, 31 and is thereby held against further advancing movement as the drive member 14 is further advanced through the jaws to a position where the junction between the drive member 14 and the first drill rod 11 is between the clamps 28 and 29.In order to reach this position, as will be appreciated from a study of Figure 4, the drive member 14 must be advanced further through the collar 37 than it projects in the position shown in Figure 4. This advancing movement is allowed, however, by the resilient slotted coupling between the pivot axis 43 of the arm 42 (and, of course the arm 41 not visible in Figures 3 to 5) which, with compression of the spring 51, allows relative longitudinal movement between the assembly comprising the drive shaft 14, the thrust bearing 15 and the movable frame member 45 to take place with respect to the arms 41 and 42 and thus the collar 37. In this way the collar 37 is retained in abutment with the front face of the clamp 28 without limiting the advancing movement of the drive rod 14.

Then the clamp 29 is engaged, the direction of rotation of the motor 16 is reversed and the drive member is caused to unscrew from the drill rod 11. Extension of the actuators 18, 19 then takes place to withdraw the drive rod 14 to its further most position to the left and then extension of the actuator 34 causes tilting of the clamp 28 to allow a new "first" rod to be located between the jaws from a convenient position offset from the line of action of the rods. Closure of the clamp 28 on the end of the new drill rod is then followed by retraction of the actuator 34 to swing this drill rod into a position in alignment with the remainder of the drill string and energisation of the motor 16 to cause the drill member 14, advanced by retraction of the actuators 18, 19, to be screwed into the drill rod to again reach the position illustrated in Figure 1.This cycle of operations is repeated, each time moving the whole drill string by the length of the new drill rod until drilling has been performed to the require depth or length.

Thereafter the drill string is withdrawn and each drill rod successively removed in a sequence which will be described hereinbelow with reference to Figures 3 to 5.

Unlike the situation of advancing movement, where the only unscrewing action takes place between the drive rod 14 and the adjacent drill rod 11, clamped by the clamp 29, it is now necessary selectively to release the first drill rod 11 from the second drill rod 12 and then to release the drill member 14 from the first drill rod 11.

As can be seen in Figure 3, the separation of the drill rod 11 from the drill rod 12 takes place after the drive member 14 (and therefore the thrust bearing 15 and motor 16 carried by the frame 17) has been withdrawn to a position such that the junction between the first and second drill rods 11, 12 is between the two clamps 28, 29. In this position the clamp 29 is closed to secure the second drill rod 12 and the clamp 28 is open to allow rotation of the drill rod 11. A collar 37 is still in the advanced position to which it is moved by the spring 47 so that it spans the junction between the drive member 14 and the first drill rod 11 so that upon energisation of the motor 16 in reverse rotation the drive member 14 transmits reverse rotation via the collar 37 to the first drill rod 11. Since the second drill rod 12 is in this position clamped the first drill rod 11 is thus unscrewed from the second drill rod 12. Figure 3 illustrates the relative positions of the components immediately after this unscrewing operation has been completed.

Thereafter, as illustrated in Figure 4, the actuators 18, 19 are extended to move the frame 17, the motor 16, the thrust bearing 15 and the drive member 14 to the left, carrying with it the frame 45 and the levers 42 which, by engagement of the foot 44 on the ramp 46 causes the collar 37 to be displaced with respect to the drive member 14 releasing the engagement with the first drill rod 11. The clamp 28 is then closed, as shown in Figure 4 and further rotation of the motor 16 causes the drive member 14 to be unscrewed from the first drill rod 11.

This is accompanied by a slight further movement to the left of the drive member 14 to withdraw this from engagement with the drill rod 11. Thereafter extension of the actuator 34 causes tilting of the clamp 28 to displace the drill rod 11 to the position shown in Figure 5 in which, upon release of the clamp 28, the drill 11 can be withdrawn. retraction of the actuator 34 then causes the clamp 28 to resume its upright position and retraction of the actuators 18, 19 displaces the drive member 14 through the clamp 28 to a position in which it can engage the drill rod 12 so that forward rotation of the motor 16 causes engagement of the drive member 14 with the drill rod 12. The actuators 18, 19 are then extended to cause withdrawal of the drill string, with the motor 16 still being rotated slowly in the forward to maintain the screwed couplings in engagement. When the junction between the drill rod 12 and the drill rod 13 is located between the clamps 28, 29 the latter is closed and reversed rotation of the motor 16 initiated. In this position the collar 37 is advanced as shown in Figure 3 and the cycle of operations is then repeated until all the drill rods have been withdrawn.

These two cycles of operation can be achieved by selective manual operation of control valves for determining clamping and unclamping of the clamps 28, 29 and the extension and retraction of the actuators 18, 19, 34 as well as selecting the direction of the motor 16.

In another embodiment, not shown, there may be provided appropriate position sensors and timers operating to cause the sequence of appropriate movements to be made cyclically and repetitively without intervention by the operator.

Claims (15)

1. A drive coupling device for apparatus for drilling holes by advancing a plurality of longitudinally coupled elongate members by means of a reciprocating drive member, in which relative rotation in one direction about the longitudinal axis of the said member occurs to release the coupling, and there are provided means for selectively transmitting torque between adjacent said members whereby to allow rotation in both directions without effecting such release.

2. A drive coupling device as claimed in Claim 1 for a longitudinally displaceable rotatable drive member having screw threaded connector means for connecting the member to a correspondingly threaded part of a driven member comprising a collar surrounding the said driven member and engaged thereon so as to be longitudinally displaceable with respect thereto and fixed for rotation therewith, the said collar being displaceable longitudinally of the said drive member between a retracted position in which it leaves the said screw threaded portion exposed, and an advanced position in which it at least partially surrounds the said screw threaded portion for cooperative engagement with a driven member screw threadedly engaged on the drive member whereby to permit bi-directional transmission of rotation between the drive member and the driven member without causing relative unscrewing thereof.

3. A drive coupling device as claimed in Claim 2, in which the said longitudinally displaceable rotatable drive member has a generally circular cross section with at least one longitudinally extending flat surface by which the said longitudinally displaceable collar is fixed for rotation.

4. A drive coupling device as claimed in Claim 2, in which the said longitudinally displaceable rotatable drive member has a generally hexagonal cross section with said longitudinally displaceable collar having a hexagonal internal surface for cooperating engagement therewith by which said collar is fixed for rotation.

5. A drive coupling device as claimed in any of Claims 2 to 4, in which rotary coupling between the said longitudinally displaceable collar and the said rotatable drive member is effected by form engagement between a part of the rotatable drive member having (a prismatic cross section) and a correspondingly shaped (prismatic) aperture passing through the said collar.

6. A drive coupling device as claimed in Claim 1 or Claim 2, in which at least part of the said rotatable drive member has a plurality of longitudinally extending splines engaged in a correspondingly splined aperture passing through the said collar.

7. A drive coupling device as claimed in any preceding claim, in which the said longitudinally displaceable rotatable member is a drive member for driving a drive string of rods or tubes the said drive member being linearly reciprocahle by drive member reciprocation means.

8. A drive coupling device as claimed in any of Claims 1 to 7, in which there are further provided means for automatically effecting relative displacement of the said collar and the said drive member in the vicinity of one end of the range of reciprocating movement of the said drive member.

9. A drive coupling device as claimed in any preceding claim, in which there are further provided drill member clamp means operable to clamp that drill member to which the drive member is connected against longitudinal and rotary motion.

10. A drive coupling device as claimed in Claim 9, in which there are two such clamp means longitudinally spaced along the path of the drive string and positioned such that the said nearest adjacent drill member and the next adjacent drill rod to which the said nearest adjacent drill member is connectable can both be clamped.

11. A drive coupling device as claimed in Claim lo in which the relative positions as of the said two clamps are chosen such that the junction between the said nearest adjacent drill member and the said next adjacent drill member can be located between the said two clamps.

12. A drive coupling device as claimed in Claim 11, in which the clamp nearest the drive member is pivoted whereby to swing a drill rod clamped thereby into an inclined position with respect to the longitudinal direction of the said drive member.

13. A drive coupling device as claimed in any preceding claim, in which there is a bank of individual control valves for selectively operating the movable parts of the device.

14. A drive coupling device as claimed in any preceding claim, in which there are provided sensors for detecting the relative positions of the movable parts, and control valves operable to perform predetermined sequences of operations which are undertaking repeatedly when advancing or retracting the drill string.

15. A drive coupling device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.