EP2252763B1 - Clamping head for an earth-drilling system - Google Patents

Abstract

The invention relates to a clamping head for an earth-drilling system comprising a hollow shaft (3) through which a drill pipe (9) can be guided, wherein a sleeve (1) is arranged coaxially on the hollow shaft (3) in such a way that it can move relative thereto, said sleeve having at least one widening end region (1b), in particular a downwardly widening end region which particularly widens in a conical shape, and wherein at least two clamping jaws (2) which can move radially with respect to the hollow shaft (3) are mounted in the hollow shaft (3) and/or on the sleeve (1), said clamping jaws being provided at their radially outer end with run-on surfaces (2b) interacting with the widening end region (1b), such that the clamping jaws (2) can be pressed radially inward as a result of the end region (1b) sliding over them and form a first clamping mechanism for a drill pipe (9), in particular such that a torque can be transmitted between the hollow shaft (3) and drill pipe (9) as a result of an interaction between the clamping jaws (2) and drill pipe (9), wherein a second clamping mechanism is provided in the hollow shaft (3) and can be used to secure a drill pipe (9) in the axial direction, in particular in order to draw a drill pipe (9) from the ground in the axial direction.

Description

The invention relates to a clamping head for an earth boring system comprising a hollow shaft (3), through which a drill pipe (9) can be guided, and wherein in the hollow shaft (3) at least two radially to the hollow shaft (3) displaceable clamping jaws (2) are mounted and form a first clamping mechanism for a drill pipe (9), wherein in the hollow shaft (3), a second clamping mechanism is provided, by means of which a drill string (9) can be fixed in the axial direction.

Such clamping heads are for example from the US 3915244 known as the closest prior art.

In the prior art, separate devices are still known, by means of which there is the possibility of pulling a drill pipe by means of the Erdbohranlage again from a hole introduced into the ground. In the prior art, it is known devices provided for this purpose, which are also referred to as elevator head, to provide separately to a chuck of the type mentioned in a drilling rig.

Because of this separate arrangement can therefore be raised by means of a Erdbohranlage either only a drill pipe or a drill pipe to be rotated. A superposition of both movements is not possible with the well-known in the art Erdbohranlagen, or requires considerable control effort to tune both heads mentioned above in their movement.

The object of the invention is to provide a clamping head for a Erdbohranlage, with which the possibility is created to make a torque transfer during a lifting movement for lifting a drill string from a wellbore to simultaneously effect a rotation of the drill string during the lifting movement can and thus simplify the lifting of the drill pipe from the ground, as by turning the adhesion between the drill pipe and soil is reduced. It is a further object of the invention to further develop a clamping head such that an operative connection between the first clamping mechanism and the linkage is achieved and preferably also that damage to a drill pipe by the clamping jaws is avoided.

This object is achieved according to the invention by a clamping head of the type mentioned, in which coaxially on the hollow shaft (3) a sleeve (1) is arranged displaceably to this, which has at least one flared end portion (1b) and the clamping jaws (2) their radially outer end with the widening end portion (1 b) cooperating thrust surfaces (2b), so that by pushing the end portion (1b) via the clamping jaws (2) they are radially inwardly pressed.

In this case, the outer movable sleeve with the widening end region is also referred to as a clamping bell due to its external shape design. The flared end region may be here, e.g. be formed cone-shaped, it may be provided that in the usual working position of such a clamping head of the expanding end portion of the sleeve is located at the lower end of this sleeve, so that the displacement of the clamping jaws takes place radially inwardly into the hollow shaft, when the sleeve on the hollow shaft is pushed down and thereby the tapered downwardly expanding end portion is pushed further and further over the ends of the clamping jaws.

The clamping jaws mentioned here can be inserted in corresponding recesses in the hollow shaft, which extend in the radial direction through the hollow shaft wall. The jaws can be attached to both the hollow shaft and the sleeve movable, or on both elements. In one embodiment, the expanding region in the axial direction of the hollow shaft extending elongated holes can pass through the outside of screws, which are screwed at least in the lateral section substantially perpendicular to the contact surfaces of the jaws to a loose connection between jaws and sleeve achieve. Thus, the jaws loosely attached to the particular conically enlarged end portion in the sleeve and can move in the axial direction within the slots relative to the sleeve, so that it can be pushed over the jaws over.

If the clamping jaws are displaced radially inwardly into the hollow shaft with the sleeve, for example by a lowering of the sleeve relative to the hollow shaft, then the inner surfaces of the clamping jaws which apply to a drill string can come into contact with it, whereby an operative connection between clamping jaws and linkage can be achieved. Such a conclusion can exist for example in a force and / or shape and / or frictional engagement. There is thus the possibility of transmitting a torque between the hollow shaft and a drill pipe, that is to achieve a rotation of the drill pipe in the soil in that the hollow shaft is rotated.

It may be provided in a first possible embodiment that the second clamping mechanism as well as the first clamping mechanism can be actuated by moving the sleeve which is displaceable on the hollow shaft. This has e.g. the advantage that only one drive must be present to move the sleeve.

In another alternative embodiment, it can also be provided that the sleeve for actuating the first clamping mechanism by means of a first drive, in particular hydraulic drive relative to the hollow shaft is displaceable and the second clamping mechanism is actuated with a second drive independent of the first drive, in particular both Drives are fixed with one side to a common support element. Thus, both tensioning mechanisms can be operated independently, e.g. in chronological succession or else at the same time, for example by synchronization in a superordinate control unit controlling the drives. The drives can be in both versions, e.g. each comprise at least one, preferably a plurality of evenly distributed in the hollow shaft cylinder-piston units.

Such a clamping head according to both alternatives has the advantage according to the invention that two different clamping mechanisms in the same clamping head are realized, wherein one of the clamping mechanisms can be optimally adapted to transmit a torque between the hollow shaft and drill pipe and the other clamping mechanism can be optimally adapted to optimally transfer an axial force application to the drill string, in particular a force to the drill pipe from the To pull out soil.

Due to the combination of both respective clamping mechanisms in one arrangement, the advantage according to the invention is furthermore achieved that both a lifting movement and a rotary movement can be exerted on the drill string simultaneously with the same clamping head. This can be done in the first alternative e.g. take place without that a special control must be provided, since both movements are coupled together.

In both alternatives, it may be provided according to the invention that the second clamping mechanism comprises at least two clamping elements preferably more clamping elements, for example three to five clamping elements, each clamping element having a radially outer guide surface which cooperates with a guide surface in the interior of the hollow shaft, so that a movement of a clamping element in the axial direction, in particular during a movement of the clamping element in the usual working position of the clamping head down a radial movement, in particular inward is effected. Such a guide surface of a tensioning element may e.g. be formed in the shape of a portion of a truncated cone.

Here, it is provided in the first alternative, as mentioned at the outset, that the individual clamping elements of the second clamping mechanism are moved, if by means of the sleeve arranged on the outside of the hollow shaft, an axial movement is carried out in particular in the usual working position down. For this purpose, a mechanical operative connection between the outer sleeve and inner clamping elements is provided, which may extend, for example, through the wall of the hollow shaft.

It can thus be achieved that by moving the sleeve on the outside of the hollow shaft, the clamping elements arranged in the hollow shaft are carried along in the same direction of movement at least in regions. According to the second alternative, the clamping elements are driven separately.

In both alternatives is effected by a corresponding arrangement of the respective guide surfaces of the hollow shaft and the clamping elements that automatically takes place when moving in the axial direction and moving in the radial direction of the clamping elements, in particular so that they are wrapped around a form-fitting to a hollow shaft of the drill string can.

The kinematic implementation of an axial movement of the clamping elements in a radial movement taking place at the same time can take place, for example, in that the cooperating guide surfaces on clamping element and hollow shaft relative to the center axis of the hollow shaft have a tendency, in particular when viewed in section have an acute angle to this ,

A form fit between the clamping elements and a drill string can be achieved by provided on the clamping elements at their radially inner regions lying contact surfaces, which are adapted to a drill string in terms of their design, for example, to the diameter of a drill string, so that these contact surfaces, for example. have at least one cylindrical portion-shaped surface area and / or may also be adapted to a shoulder which is provided on the drill string, or a step at which the diameter of the drill string changes, in particular in the direction from top to bottom tapers.

Such a taper can be made at the said shoulder or step, for example, by a right-angled step relative to the axis of the drill pipe, or by a conical step or any other shapes. The contact surfaces of the clamping elements thus also have surface areas which are adapted to such a shoulder or step, so that by a positive connection between the clamping elements and a drill string due to the system of the clamping elements on such a shoulder or step an axial lifting force can be exerted on the drill string when the contact surface rests against the shoulder / step, without the clamping elements in the axial direction relative to the drill string slip. The contact surfaces can be arranged on a clamping element preferably at its upper or lower end.

In order to obtain a corresponding guide surface as counter surface for those guide surfaces on the respective clamping element, it may be provided in a preferred embodiment, in particular in both alternatives, that such a guide surface is formed inside the hollow shaft by a radially inwardly projecting annular region whose inner Recess forms a tapered, in particular frusto-conical lateral surface which is arranged coaxially about the center axis of the hollow shaft, in particular wherein said frustoconical surface is tapered downwards in the usual working position of the clamping head. Just by the downward taper is achieved here that during a downward movement of the clamping elements within the clamping head, a displacement of these clamping elements takes place radially inwardly when the guide surface slides on the clamping element on the frusto-conical lateral surface of the ring area along.

The formation of a frustoconical surface on the inner ring portion inside the hollow shaft has manufacturing advantages, since such a frustoconical surface can be achieved in a simple manner by an inner boring of a shaft. For example, this can be made of a solid material, a hollow shaft.

The radially outer guide surfaces of the clamping elements can furthermore be designed as outer conical surface areas corresponding to the frustoconical lateral surface. This results if both the guide surfaces on the clamping elements and those on the projecting annular region are frusto-conical, or form a portion of a frusto-conical lateral surface, that there is only one specific position in which the respective guide surfaces of the clamping element and ring area touching each other in a form-fitting manner, since outside of this particular position, the respective diameters of the individual conical surfaces do not match each other relative to the center axis of the hollow shaft.

It is therefore provided in a preferred embodiment, that the respective guide surfaces of the clamping element and annular region are adapted to each other, that increases the positive connection between these corresponding guide surfaces with increasing positive engagement between the clamping elements and a drill pipe, ie in particular when the clamping elements by the Sleeve down and thus simultaneously pushed inward.

Thus, the second clamping mechanism can be designed so that in the moment when there is optimal positive engagement between the clamping elements and a drill pipe and an optimal positive connection between the corresponding guide surfaces is given. It will be optimally transferred the respective forces between the surfaces in this way while avoiding too high local pressures. Such an embodiment also has the advantage that in a case when there is no positive connection between the clamping element and drill pipe or between the corresponding guide surfaces, these guide surfaces do not rest over their entire surface area but only selectively or linearly to each other, so that the friction between the guide surfaces is reduced in this position of the clamping elements.

The same configuration may also be provided between the guide surfaces on the clamping jaws of the first clamping mechanism and the conically widening end portion of the outer sleeve. All of the above statements regarding the construction of the guide surfaces between the clamping elements of the second clamping mechanism and the frusto-conical lateral surface of the annular region apply analogously to the clamping jaws of the first clamping mechanism and the frustoconical widening end portion of the sleeve.

In another possible embodiment, it may also be provided in both alternatives, that the inner circumferential surface of the downwardly flared frustoconical end portion of the sleeve grooves, in particular from top to bottom extending grooves having a flat groove bottom. It may be this groove bottom directly or indirectly via an intermediate element with flat contact surfaces of the clamping jaws of the first clamping mechanism in operative connection. Compared to frustoconical active surfaces, this design has the advantage that higher forces can be transmitted over the larger areas.

It may be provided that the groove bottom of a groove acts directly on a flat contact surface of a clamping jaw or in a preferred embodiment, that in a groove a guide element is fixed, in which a clamping jaw is guided with its a flat contact surface having end. The entrance to the prior art called leadership by screws and slots can be omitted and transferred in addition to the advantage of leadership to higher forces. Such a guide element acting as an intermediate element may e.g. is formed as a U-profile with undercut profile legs, i. the inner free width between the profile legs is smaller in the upper area than in the lower area near the inner bottom of the U-profile.

The guide can then be formed by in the two side surfaces of a clamping jaw in the region of the stop surface having the end parallel to the plane stop surface formed grooves, which engage provided on a guide element projections, in particular the respective non-undercut portion of the profile legs.

In a further preferred embodiment, it is provided that a clamping element is displaceable in the axial direction on a bolt arranged parallel to the hollow shaft axis, which penetrates a clamping element or a radial outward-pointing projection arranged thereon. This has the advantage that when using a plurality of individual clamping elements, these each have a guide and can only move along this guide in the axial direction in the interior of the hollow shaft. For example, a tilting of the clamping elements is avoided relative to the drill pipe. In order to simultaneously allow in addition to the guided movement in the axial direction that during an axial movement, a radial movement in particular inward is possible, it is preferably provided that such a bolt rests in a recess of the clamping element or its projection mentioned, which in extends in the radial direction, that is formed, for example, in the manner of a slot in the radial direction. Thus, in a movement of a clamping element in the axial direction of this can be performed in the axial direction of the bolt along this, but also simultaneously move perpendicular to the extension of the bolt in the radial direction.

As mentioned above, it is provided according to the invention in a first alternative that the clamping elements are actuated by a movement of the outer sleeve. For this purpose, an operative connection can be provided from the interior of the hollow shaft to the outer sleeve. In a preferred embodiment, the clamping elements are movable by means of an arranged inside the hollow shaft actuator in the axial direction, in particular in the direction of increasing positive engagement relative to the drill string, wherein the actuating element is connected to the externally arranged on the hollow shaft sleeve by at least one radial web, which extends through a recess in the hollow shaft.

In the second alternative, it may be provided that the clamping elements by means of at least one arranged inside the hollow shaft, actuating element in the axial direction, in particular in the direction of increasing positive engagement are movable, wherein the at least one actuating element with a pressure ring surrounding the sleeve by at least one radial web is connected, which extends through a recess in the hollow shaft, in particular wherein the at least one web is movable in a recess in the axial direction of the hollow shaft.

In this case, preferably, the pressure ring have a particular upper tread on which the second drive, in particular hydraulic cylinder of the second drive by means of ball and / or roller bearings is supported. Thus, the hollow shaft and the pressure ring can be rotated relative to a drive.

To make this possible, the first drive or, in the first alternative, the single drive, in particular the hydraulic cylinder of this drive, can be connected to a ring element surrounding the sleeve in the second and in particular also in the first alternative supported in the axial thrust direction via ball and / or roller bearings on the sleeve, in particular wherein the ball and / or roller bearings are enclosed between two surrounding the sleeve collar. The thrust or tensile forces can be transmitted through different bearings on the sleeve, so in particular depending on a bearing or a group of bearings for the overrun phase and the traction phase can be provided.

In both alternative types of drive, it is preferably provided that a recess in the hollow shaft has a longitudinal extent in the axial direction of the hollow shaft, so that upon movement of the sleeve or a pressure ring in the axial direction, a web extending in the radial direction through such a recess in this axial direction within the recess is also movable. Thus, the movement of a sleeve or a pressure ring on the outside of the hollow shaft can be transmitted into the interior of the hollow shaft characterized in that the actuator connected by the webs moves together with the sleeve. The movement of the actuating element can then be transmitted to the clamping elements in various ways, for example, by an actuating element acting directly and directly on a clamping element or else by an actuating element acting indirectly via intermediate-mounted elements on a clamping element, as will be explained later.

It may be provided in a particularly preferred embodiment, regardless of the nature of the action, that an actuating element is annular, wherein the inner recess is provided to surround a drill string and wherein on the ring of this actuating element all clamping elements are movable simultaneously.

Furthermore, it can also be provided that the aforementioned bolts, on which the clamping elements move along, are fastened to the actuating element. For example, a fastening can be effected by means of a screw connection, it likewise being possible for the bolts to be provided in Submerge guide holes which are provided on the annular portion which is formed in the hollow shaft for forming the frusto-conical guide surface area. The bolts are arranged at a distance from the center axis around this, in particular in a uniform angular pitch, as well as the clamping elements movably attached thereto.

In a further preferred embodiment, a clamping element, in particular each clamping element which is provided in the hollow shaft, in the direction of increasing positive engagement and thus in particular in a downward direction relative to the usual working position against a restoring force be displaced.

Such a restoring force may, for example, be exerted by a compression spring, in particular one which is supported on one side, in particular on the underside, on the tensioning element and on the other side, in particular on the top of the annular area mentioned at the outset. In this case, such a compression spring surround a bolt also mentioned above.

Such a restoring force can also be generated by a compression spring whose one end is supported directly or indirectly via a ring on an inner shoulder of the hollow shaft adjacent to the frusto-conical shell surface and whose other end is supported directly or indirectly via a ring on a radially projecting upper region of a clamping element, in particular supported from below.

The movement of the clamping elements in the direction of increasing positive locking against a restoring force has the advantage that the clamping element can be pressed by this restoring force in the axial direction to a realized on a drill string shoulder or step. Thus, this causes that at the moment when the drill string a clamping element relieves this clamping element is pushed out by the restoring force from the positive connection between the guide surfaces, that is pressed, for example, based on the usual working position upwards. As a result, the drill string is released from the clamping elements. Such relief between drill pipe and the clamping element can be achieved, for example, when a drill pipe after the Lifting by means of such a clamping head according to the invention is placed on the ground and the clamping head moves relative to the drill string away from the shoulder of the drill string down in the axial direction of the drill string.

The removal of the clamping elements in the radial direction from a drill pipe to the outside can be further supported in a development that the clamping elements, in particular at its upper end radially inwardly lying, in particular downwardly tapered truncated cone-shaped contact surfaces, by means of which in an operative connection arranged in the hollow shaft corresponding contact surfaces, a clamping element in an upward movement is radially outwardly displaceable, in particular when the respective clamping element moves axially upwards and thereby the respective contact surfaces come into operative connection.

The corresponding abutment surfaces arranged in the hollow shaft can be e.g. be formed by an outer lower frustoconical, in particular downwardly tapering portion of a coaxially mounted in the hollow shaft in the upper region of the tube. This tube may e.g. be attached by an attached ring or collar or webs on the hollow shaft, in particular at its inner upper portion.

In a further preferred embodiment, especially in the case of the first drive alternative, it is provided to make an indirect action of the actuating element on the respective clamping elements by means of at least one compression spring which is provided between the actuating element and each clamping element. This ensures that a force does not act directly between the actuating and clamping element, but that the force is applied in each case by the compression spring. This has the additional advantage that over a certain predetermined axial movement path substantially always the same force is exerted on the clamping element, which results from the spring constant of the compression spring in dependence on the compression travel.

It may be provided that such a compression spring is arranged directly between the actuating element and the clamping element or in a particular preferred embodiment, that such a compression spring between an actuating element and an intermediate element, for example an intermediate ring is arranged, which lies between the actuating element and the clamping element. In turn, all clamping elements can be contacted simultaneously via such an intermediate ring. Accordingly, spring elements can be arranged between the mutually facing annular surfaces of the intermediate ring and the actuating element, for example preferably at the positions at which the aforementioned bolts can extend from the actuating element through the intermediate ring and the clamping elements. For example, each of these springs can surround a bolt.

Such an embodiment according to the invention has the particular advantage that in the first drive alternative, a sleeve in the axial direction is movable relative to the hollow shaft, wherein initially by the indirect action of the actuating element on the compression springs, the clamping elements are movable into a positive connection with a drill string, said after Achieving this positive connection between the actuating element and clamping elements or actuator and intermediate ring an axial range of motion remains.

This axial movement range results here essentially by the fact that the compression springs are not fully compressed when the positive locking is reached. Accordingly, there remains an axial range of motion which is given by the compression of the compression springs obtained in positive engagement up to the maximum possible compression of the compression springs, for example when their turns abut one another or a separate stop is provided. The design of the clamping head according to the invention can therefore be such that due to this remaining range of motion even with existing positive connection between the clamping elements and the drill string, the outer sleeve in this given range of motion can be moved in the axial direction, until a decision between the clamping jaws of the first clamping device and the drill pipe is created. This conclusion can be given for example by a force and / or shape and / or frictional engagement between the jaws of the first clamping device and the drill pipe.

It is thus in the first alternative drive at a movement of the sleeve in particular based on the usual working position in the axial direction down initially achieved a positive connection for axial fixing of the drill string with the second clamping mechanism and after this is achieved, by moving on the sleeve of the operative closure between the jaws of the first tensioning device and the drill pipe to thereby transmit a torque can.

In both drive alternatives, it may further be provided that at the lower end of the downwardly widening, in particular conically widening end portion of the sleeve a particular perforated ring member is arranged which receives in its inner free diameter, the hollow shaft and which with an upstanding collar the Encompasses end area. This achieves a stabilization of the sleeve, which otherwise tends to spread when applying the compressive forces on the jaws. This spreading can be prevented by the stabilizing ring element.

Thus, such an inventive clamping head when lifting the drill string in addition to the tensile forces exerted from the soil out at the same time allows the pipe linkage to rotate due to the ability to transmit torque and so reduce the adhesion between the drill pipe and soil, which greatly simplifies the lifting process. In this case, the clamping jaws of the first clamping mechanism, e.g. have a surface design of cooperating with a drill string surface, which produce a good operative conclusion. For example, the surface may have a structuring and / or preferably a coating which acts as a friction lining. Such a coating may e.g. the activity-enhancing particles, e.g. Sand, diamonds etc. So the force can be introduced over a large area in the drill pipe, whereby local damage fails.

In reverse movement of the sleeve, ie based on a normal working position from bottom to top dissolves in the first alternative drive thus in reverse order first the effective connection between the jaws and the drill pipe in which case when the drill string in the chuck hangs the Positive engagement between the clamping elements of the second clamping device and the drill pipe initially maintained, since the drill pipe rests on his shoulder / stage, which was described at the beginning with its weight on the clamping elements and thus now this instead of the sleeve / actuator via the drill pipe in the axial direction downwards and thus loaded in the direction of gravity, so that the positive locking remains self-locking.

Only as mentioned in the beginning, in the case when the drill pipe relieves the clamping elements, for example, placed on the ground, the clamping head lowers relative to the drill string, whereby the positive connection between the drill string or the shoulder and the clamping elements is repealed and the clamping elements the spring load to be moved in the axial direction upwards and thus release the drill pipe. In the case of the second drive alternative, the separate drive is to be actuated in order to produce or release the positive locking of the clamping elements.

In the device according to the invention, it is preferably provided in both drive alternatives to arrange the second clamping mechanism relative to a usual working position of the clamping head above said first clamping mechanism. It is also possible to reverse this arrangement.

Figur 1

eine Schnittdarstellung durch einen erfindungsgemäßen Spannkopf der ersten Antriebsalternative

Figur 2

eine Ausschnittdarstellung mit der Federanordnung nach Figur 1

Figur 3

eine perspektivische Ansicht eines Spannkopfes der zweiten Antriebsalternative

Figur 4

eine Schnittdarstellung des Spannkopfes nach Figur 3

Figur 5

eine Darstellung eines Spannelements

Figur 6

die alleinige Darstellung der Hohlwelle

Figur 7

die alleinige Darstellung der Hülse

Figur 8

die alleinige Darstellung eine Spannbacke des ersten Spannmechanismus

Figur 9 und 10

die Darstellung eines Führungselementes zum Führen einer Spannbacke gemäß Figur 8

A preferred embodiment of the invention is shown in the following figures. Show it:

FIG. 1

a sectional view through a clamping head according to the invention the first alternative drive

FIG. 2

a detail view with the spring arrangement according to FIG. 1

FIG. 3

a perspective view of a clamping head of the second drive alternative

FIG. 4

a sectional view of the chuck after FIG. 3

FIG. 5

an illustration of a clamping element

FIG. 6

the sole representation of the hollow shaft

FIG. 7

the sole representation of the sleeve

FIG. 8

the sole representation of a jaw of the first clamping mechanism

FIGS. 9 and 10

the representation of a guide element for guiding a jaw according to FIG. 8

The FIG. 1 shows a side sectional view of a clamping head according to the invention of the type generally described in the first drive alternatives. Visible here is a hollow shaft 3, on the coaxial and axially movable sleeve 1 is arranged, the lower end portion widens conically in the present embodiment down.

In the hollow shaft radial recesses 3d are provided in the vicinity of the lower end, pass through the clamping jaws 2 in the radial direction, which can enter into an operative conclusion with their inner surfaces 2a a form fit, force or frictional engagement with a drill string 9, if this Clamping jaws 2 are radially displaced maximally inwards. The areas 2a may be e.g. have a toothed surface.

In order to achieve this radial inward displacement, the clamping jaws 2 radially outward contact surfaces 2b, which are formed corresponding to the inner conical surface 1b of the lower end portion of the sleeve. Here, the adjustment of the corresponding surface areas may be such that they enter into a maximum positive fit, although the effective connection between the radially inner surfaces 2a and the drill string is given, so substantially the sleeve 1 is also shifted maximum down.

A second clamping mechanism can also be seen in the interior of the hollow shaft above the clamping jaws 2, which for example comprises a plurality of, in particular four, clamping elements 4 which are arranged coaxially to the center axis 10 of the drill pipe 9 or the hollow shaft 3 and have radially inwardly lying contact surfaces 4b , which are designed to form-fitting to the Drill 9 and its shoulder 9a to be applied. At this shoulder 9a, the drill string 9 tapers from top to bottom, in this case conical / conical.

The clamping elements 4 further have radially outer guide surfaces 4a, which are arranged at an acute angle to the center axis relative to this sectional view and which are further formed corresponding to guide surfaces 3a in the interior of the hollow shaft 3. These guide surfaces 3a inside the hollow shaft 3 can here be formed in the form of an annular region 3b which extends radially inward from the Hohlwellenwandung the hollow shaft 3 and having a coaxial to the center axis recess which is frusto-conical and tapers towards the bottom. Here, the corresponding guide surfaces 4a and 3a on the clamping elements and the annular portion 3b of the hollow shaft 3 are adapted to each other that at the maximum fit shown here between the clamping elements 4 and the drill string 9 and a best fit between the radially outer guide surfaces 4a of the clamping elements and the inner frusto-conical surface portion 3a of the annular region 3b results.

It can also be seen here that the clamping elements 4 have in their upper region a projection 4c pointing radially outwards, through which guide pins 6 pass. Through these guide pins, the clamping elements are guided in the axial direction and held their position, further provided in said radial projections 4c of the clamping elements 4 here in the radial direction slots are provided so that in an axial movement of the clamping elements 4 from top to bottom and the Guide between the surfaces 3a and 4a at the same time the clamping elements 4 can be moved radially inward in the game of said slots.

Visible is here in particular with reference to the FIG. 2 a special spring construction in which the respective clamping elements 4 are displaced against a spring force which is used up by so-called opening springs 7 downwards in the direction of increasing positive engagement between the clamping element and the drill pipe become. In this case, the opening springs 7 are supported between the radial projections 4c of the clamping elements 4 and the annular region 3b, for which purpose the cattle region 3b has a blind bore.

It can be seen in this construction further that an actuating element 5 is provided as a driver for the clamping elements 4, which is formed substantially annular and surrounds the drill string 9 and which is connected by webs through recesses 3 c with the outer sleeve 1. Between the actuating element 5 and the clamping elements 4, an intermediate ring 5a is further arranged here, which simultaneously contacts all the clamping elements 4 from above.

Between the intermediate ring 5a and the actuating element 5, a so-called closing compression spring 8 is arranged, which is provided to indirectly transmit the movement of the actuating element 5 with the sleeve 1 via the spring 8 to the intermediate ring 5a and thus to the clamping elements 4. Thus, the clamping elements 4 are pressed by the spring forces acting through the compression springs 8 in the axial direction down in the direction of increasing positive engagement, but not by the forces on the sleeve, for example with a hydraulic drive device or with the sleeve on the jaws. 2 be exercised. It is here in particular from the FIG. 2 Also seen that when reaching maximum fit between clamping jaws 4 and linkage 9, as is the FIG. 1 shows a gap 10 between actuator 5 and intermediate ring 5a remains. This gap 10 provides a range of motion, in which the sleeve 1, even if maximum positive engagement between the clamping elements 4 and the drill string 9 is achieved, can be moved even further down, so the jaws 2 with maximum force on the drill string 9 to press. It thus causes first the drill string 9 is fixed in the axial direction due to the contact between the shoulder 9a and the clamping elements 4 and the continued also by the effective connection between the clamping jaws 2 and the drill string 9, a torque on this by a rotation of the hollow shaft 3 can be transmitted. Thus, when lifting the drill string 9 this can also be rotated at the same time, which simplifies the lifting process.

The FIGS. 3 and 4 show a clamping head of the second alternative according to the invention, in which separate actuators, here hydraulic cylinder-piston units are used for actuating the first and second clamping mechanism. In the following, essentially only the Figures 1 and 2 not provided or not mentioned features described.

The sleeve 1 has here above the flared portion 1b two spaced collars 1c and 1d, of which the collar 1c is integral with the sleeve 1 and the collar 1 d is formed by a screw-on the sleeve ring. Both collars enclose bearings 11a and 11b, bearing a downward force (thrust) with bearings 11a and an upward force (traction) with bearing 11b on the sleeve. This force is introduced by means of a surrounding the sleeve 1 ring member 12 through the bearings in the sleeve. Thus, the sleeve 1 can be rotated with the hollow shaft 3, wherein the coupled with the first drive ring member 12 is stopped unrotated. The first drive is hereby constituted by the cylinder-piston assemblies 13 which are mounted on the ring member 12 e.g. are attached to the piston rod and have a uniform angular distribution around the ring member around.

The second drive also comprises cylinder-piston assemblies 14 with uniform angular distribution around the chuck, which introduce the force generated on ball and / or roller bearings 15 on a running surface 16a of a pressure ring 16, by the not shown here recesses 17 in the hollow shaft. 3 is connected by webs with an annular actuating element 5, so that the movement of the pressure ring 16 is transmitted to the interior of the hollow shaft 3.

Here, the actuating element 5 acts directly from above on the clamping elements 4, in particular on the upper radially outwardly projecting edge 4c. The clamping element 4 used here is in the FIG. 5 shown in detail with the with Figures 1 and 2 matching reference numerals.

Compared to the execution Figures 1 and 2 Here, a clamping element 4 still has a contact surface 4d on the inner upper portion, which has the shape of a portion of a truncated cone and cooperates with corresponding here Stop surfaces 17a at the frustoconical lower end of a tube 17 that is coaxially mounted in the hollow shaft 3 via the ring member 17b and a drill string 9 surrounds.

The FIG. 4 further shows a compression spring mechanism 18 for applying force to the clamping element 4 in the opening direction. Here, a spring is inserted between two rings, wherein the lower ring rests against an inner shoulder above the frusto-conical inner lateral surface 3a of the hollow shaft 3 and the upper ring at the bottom of the projecting portion 4c of a clamping element. Here, the spring mechanism is shown for the sake of clarity in the compressed position, but the clamping elements 4 in the pushed-up position.

The FIGS. 3 and 4 show beyond that at the top of the hollow shaft 3, a flange 3e is arranged, which is connected by means of a clamping ring 19 with the corresponding flange 20 of a rotary drive to rotate the hollow shaft 3 and sleeve 1 relative to a support element, not shown here, on which both drives and 14 are attached.

At the bottom of the hollow shaft 3 is a funnel-shaped insertion piece 21 to facilitate the insertion of the drill string 9. This insertion piece 21 may be removably disposed below in the hollow shaft 3.

At the lower end of the downwardly widening portion 1 b of the sleeve 1, a stabilizing ring 22 is arranged, which surrounds the sleeve below with its upstanding outer collar and thus prevents spreading of the sleeve 1 under load.

The FIGS. 6 and 7 show the hollow shaft 3 and the sleeve 1 as separate components. In FIG. 7 can be seen in the sleeve 1 that this in the preferred embodiment, groove 23 in the inner frusto-conical surface 1 b, which extend from top to bottom and have a uniform angular pitch. The grooves 23 have plane groove bases, in which the guide elements 24 according to FIGS. 9 and 10 can be used.

These guide elements 24 have the shape of a U-profile with a planar inner base 24a and profile legs 24b which protrude inwardly at the outer region with a step, so that the guide element 24 forms an undercut groove. Here, the height of the guide elements 24 can decrease in relation to the subsequent positioning in a groove 23 ach upwards.

The guide element 24 forms a rail guide for a respective clamping jaw 2 of the first clamping mechanism, which has on its two sides in each case a groove 2c, which runs parallel to the surface thereof near the contact surface 2b which is planned here. In the groove 2c, the non-undercut portion 24c of each profile leg 24b of a guide element 24 einliegen, whereby the clamping jaw 2 is guided in the sleeve safely. In this case, the plane contact surface 2b bears against the planar inner base 24a, in particular so that large forces can be transmitted.

With regard to all embodiments, it should be noted that the technical features mentioned in connection with an embodiment can not only be used or are used in the specific embodiment, but also in the other embodiments. All disclosed technical features of this description of the invention and the figures are to be classified as essential to the invention and can be combined with each other or used alone. It is understood throughout the disclosure with the mention that a feature may be provided or a method step can be performed also an embodiment of the invention in which the feature in question is provided or a respective method step is performed.

Claims (15)

1. Clamping head for a drilling rig, comprising a hollow shaft (3), through which a drill pipe (9) can be fed, and wherein at least two clamping jaws (2) which can be displaced radially in relation to the hollow shaft (3) are mounted in the hollow shaft (3) and form a first clamping mechanism for a drill pipe (9), wherein a second clamping mechanism is provided in the hollow shaft (3), by means of which a drill pipe (9) can be fixed in an axial direction, characterised in that a sleeve (1) is arranged coaxially on the hollow shaft (3) in such a way that it can move relative thereto, said sleeve having at least one widening end region (1b) and the clamping jaws (2) being provided at their radially outer end with stop faces (2b) interacting with the widening end region (1b), such that the clamping jaws (2) can be pressed radially inward as a result of the end region (1b) sliding over them.
2. Clamping head according to claim 1, characterised in that the second clamping mechanism can be actuated through the movement of the sleeve (1) or the sleeve (1) can be displaced relative to the hollow shaft (3) in order to actuate the first clamping mechanism by means of a first drive (13) and the second clamping mechanism can be actuated by means of a second drive (14) which is independent of the first drive (13), wherein both drives (13, 14) are fixed to a common mounting element.
3. Clamping head according to one of the preceding claims, characterised in that the second clamping mechanism comprises at least two clamping elements (4), wherein each clamping element (4) comprises a radially outer guide surface (4a) which interacts with a guide surface (3a) on the inside of the hollow shaft (3), so that through a movement of a clamping element (4) in an axial direction, in particular downwards, a radial movement, in particular inwards, can be effected and the clamping elements (4) each possess radially inward-lying, in particular conical contact surfaces (4b), by means of which these can be brought into diametrical contact, in a positive-fitting manner, with a drill pipe (9), in particular with a shoulder/step (9a) formed on a drill pipe (9).
4. Clamping head according to claim 3, characterised in that a guide surface (3a) is formed on the inside of the hollow shaft (3) through an annular region (3b) projecting radially inward, the inner opening of which forms a narrowing, in particular conically narrowing lateral surface (3a) which is arranged coaxially around the central axis (10) of the hollow shaft (3), in particular which narrows downwards, wherein the radially outer guide surfaces (4a) of the clamping elements (4) are designed as outer conical surface areas corresponding to said conical lateral surface (3a), in particular wherein the positive fit between the corresponding guide surfaces (3a, 4a) increases with an increasing positive fit between the clamping elements (4) and a drill pipe (9).
5. Clamping head according to claims 3 to 4, characterised in that a clamping element (4) is displaceable in an axial direction on a bolt (6) arranged parallel to the axis of the hollow shaft (10), in particular wherein the bolt (6) lies in an opening, extending in a radial direction, in the clamping element (4) or a radial projection (4c) arranged thereon.
6. Clamping head according to claim 5, characterised in that the clamping elements (4) can be moved in an axial direction, in particular in the direction of increasing positive fit, by means of an, in particular annular, actuating element (5) arranged on the inside of the hollow shaft (3), wherein the actuating element (5) is connected with the sleeve (1) by means of at least one radial web which extends through an opening (3c) in the hollow shaft (3), in particular wherein the at least one web is movable within an opening (3c) in the axial direction of the hollow shaft (3).
7. Clamping head according to claim 6, characterised in that the bolts (6) are fixed to the actuating element (5), in particular wherein the bolts (6) descend into guide bores in the annular region (3b).
8. Clamping head according to one of claims 4, 6 or 7, characterised in that a clamping element (4) is displaceable in the direction of increasing positive fit against a resisting force, in particular a force applied through a pressure spring (7).
9. Clamping head according to one of the claims 6 or 7, characterised in that the actuating element (5) acts indirectly via at least one pressure spring (8) on a clamping element (4), in particular wherein the pressure springs (8) are arranged between an actuating element (5) and an intermediate ring (5a) and the intermediate ring (5a) contacts all clamping elements (4) simultaneously.
10. Clamping head according to claim 9, characterised in that the sleeve (1) can be moved in an axial direction relative to the hollow shaft (3), wherein the clamping elements (4) can first be moved into a positive fit with a drill pipe (9) through the indirect action of the actuating element (5) via pressure springs (8) and after achieving this positive fit between actuating element (5) and clamping elements (4) or between the actuating element (5) and an intermediate ring (5a) an axial movement range (10) remains, in particular through a play in the pressure springs (8), wherein an interlock, in particular a force-locking and/or form-locking and/or frictional connection between the clamping jaws (2) of the first clamping device and a drill pipe (9) can be effected through a further axial movement within this movement range (10).
11. Clamping head according to claim 4, characterised in that the clamping elements (4) can be moved in an axial direction, in particular in the direction of increasing positive fit, by means of at least one, in particular annular, actuating element (5) arranged on the inside of the hollow shaft (3), wherein the at least one actuating element (5) is connected with a pressure ring surrounding the sleeve (1) via at least one radial web, which extends through an opening (3c) in the hollow shaft (3), in particular wherein the at least one web is moveable within an opening (3c) in an axial direction of the hollow shaft (3) and wherein the pressure ring (16) possesses an, in particular upper, running surface on which the second drive (14), in particular hydraulic cylinders (14) of the second drive, is supported by means of ball and/or roller bearings (15).
12. Clamping head according to one of claims 2, 3, 4 or 11, characterised in that the first drive (13), in particular hydraulic cylinders (13) of the first drive are connected with a ring element (12) surrounding the sleeve (1), which is supported on the sleeve (1), in both an axial direction of tension and an axial direction of thrust, by means of ball and/or roller bearings (11a, 11b), in particular wherein the ball and/or roller bearings (11a, 11b) are enclosed between two collars (1c, 1d) surrounding the sleeve (1).
13. Clamping head according to one of claims 3 or 11, characterised in that the clamping elements (4) possess, in particular on their upper ends, radially inward-facing, in particular downwardly-narrowing stop faces (4d) in the form of conical sections, by means of which, in an operative connection with corresponding stop faces (17a) arranged in the hollow shaft (3), a clamping element (4) is displaceable radially outwards during an upwards movement and the corresponding stop faces (17a) arranged in the hollow shaft (3) are formed through a tube (17) fixed coaxially in the upper region of the hollow shaft (3), said tube possessing an external lower conical section (17a).
14. Clamping head according to one of the claims 1 to 4, or 11 to 13, characterised in that an, in particular, perforated ring element (22) is arranged at the lower end of the widening, in particular conically widening end region (1b) of the sleeve (1) which receives the hollow shaft (3) in its inner free diameter and which embraces the end region with an upwardly projecting collar.
15. Clamping head according to one of the preceding claims, characterised in that the inner lateral surface of the downwardly-widening, in particular conical end region (1b) of the sleeve (1) is provided with grooves (23), in particular grooves (23) running from above to below with a planar base, in particular which are operatively connected, directly or indirectly via an intermediate element (24), with planar stop faces (2b) of the clamping jaws (2) of the first clamping mechanism, wherein a guide element (24) is fixed in a groove (23) in which a clamping jaw (2) guided by its end possessing a planar stop face (2b), lies, in particular wherein a guide element (24) is designed as a U-profile with undercut profile arms (24b) and wherein the guide is formed through grooves (2c) formed in the two lateral surfaces of a clamping jaw (2) in the region of the end possessing the stop face (2b), running parallel to the planar stop face, into which projections (24c) formed on a guide element (24), in particular the non-undercut part (24c) of the profile arms (24b) engage.

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