The present invention relates to an improved pipe clamp according to the introductory portion of the independent claim.

In particular, it relates to such a pipe clamp intended for gripping a drill pipe. Background of the invention

Pipe clamps are used for holding a pipe or a rod in a fixed position while the pipe is treated. The pipe may for example be constituted by a drill pipe and the treatment in question may refer to twisting loose a boring head from the drill pipe. An example of such a pipe clamp is disclosed by DEI 02006039096. The document describes a pipe clamp with two gripping elements that hold the pipe at two pipe portions. One gripping element may be twisted from its nominal position in order to be able to receive bent pipes. The pipe clamp is intended for receiving pipes of a given size, and in order to receive pipes of another diameter, components in the design need to be replaced, which is time consuming and makes the device with accompanying components for replacement complex. The design is generally complex and therefore costly.

An object of the invention is therefore to provide a more simply designed pipe clamp that may receive pipes of varying diametres.

These and other objects are attained by a pipe clamp according to the characterising portion of the independent claim.

Summary of the invention

The invention relates to a pipe clamp intended to grasp and using a holding element 5 hold firm an elongated element 4 with at least a first 1, lal-2, lbl-2 gripping element with a first longitudinal axis, and a second 2, 2al-2 2b 1-2 gripping element with a second longitudinal axis. The first and second gripping elements have a nominal position where a straight, elongated element of even thickness with a main longitudinal axis may be received in the gripping elements. In the nominal position, the first and second longitudinal axes are parallel to the main longitudinal axis. At least a primary gripping element is provided with a device for translating the primary gripping element orthogonally to the main longitudinal axis, and this advantageously makes it possible to hold elongated elements with varying cross sectional sizes in a well defined direction.

In one advantageous embodiment, at least a secondary gripping element is provided with a device for angling the secondary gripping element from the main longitudinal axis. Thus, the pipe clamp may advantageously hold bent elements in a well defined direction. The gripping element may also be provided with a device for translating the gripping element orthogonally from the main longitudinal axis, and also be provided with a device for angling the gripping element from the main longitudinal axis.

In yet another advantageous embodiment at least one gripping element 1, lal-2, lbl-2, 2, 2al-2 2bl-2 is designed to receive the elongated element 4 in V-shaped jaws or in a pair of V-shaped jaws. Between the pair of V-shaped jaws, the gripping element may be provided with a holding element 5 that typically prevents the elongated element 4 from rotation around its axis.

The pipe clamp typically comprises a handle 6-7 for turning a portion of the elongated element 4 around its axis, usually a boring head 8 on a drill pipe. With the longitudinal axis of the drill pipe well defined, the risk that the boring head is forced in a radial direction or that the boring head threads are damaged is minimized.

Brief description of the drawings

Fig. 1 shows an embodiment of a pipe clamp as seen from the short side

Fig. 2 shows the pipe clamp with a drill pipe as seen at angle from the short side

Fig. 3 shows the pipe clamp from its wide side

Fig. 4 shows the pipe clamp from its wide side with a V-block pair raised from its nominal position

Fig. 5 shows the pipe clamp from its wide side with the V-block pair turned from its nominal position Description of a preferred embodiment

The invention refers to a pipe clamp intended for holding a pipe in a fixed position for treatment. A typical application is that the pipe clamp holds a drill pipe in position while a boring head to is twisted loose from the drill pipe. The pipe clamp is used in this way in the disclosed

embodiment. The pipe clamp extends along a longitudinal axis and the pipe is intended to be arranged essentially parallel to the longitudinal axis. The pipe clamp is illustrated from its short side, that is with the observer near the longitudinal axis of the pipe clamp, and from the wide side of the pipe clamp, that is with the observer at the same height as the pipe clamp but along an axis which is perpendicular to the longitudinal axis of the pipe clamp.

Fig. 1 shows an embodiment of a pipe clamp as seen from the short side. The pipe clamp comprises two pairs of V-blocks lal-2, lbl-2, 2al-2 2bl-2, where each V-block is constituted by a pair of jaws angled from each other approximately orthogonally. Each jaw has a serrated surface in order to achieve maximum grip on objects placed in the jaws. The jaws of each pair of V-blocks extend towards a corner of the jaws, and the drill pipe is placed at the bottom of the corner of the jaws. Each pair of V-blocks support the drill pipe at two points and thus controls how the pipe stretches, such that the pipe extends in parallel with the longitudinal axis of the pipe clamp when the pipe clamp is in its resting position. Both pairs of V-blcoks are arranged such that the drill pipe is supported at four points that sits on a straight line which is parallel to the longitudinal direction of the pipe clamp.

Both pairs of V-blocks are arranged on a base 3 that extends in parallel to the longitudinal axis of the pipe clamp. With a drill pipe positioned as close to the bottoms of the V-blocks as possible, it is held in place by elements that are illustrated in the proceeding figure, but that have been eliminated from this figure in order to facilitate understanding. The pipe clamp is also provided with further components that have been eliminated from the figure for the same reason.

Fig. 2 shows the pipe clamp with a drill pipe 4 as seen at angle from the short side. The pipe clamp comprises two V-block pairs 1 , 2 and the drill pipe rests at the bottom of the two V-block pairs. In order to prevent the drill pipe from rotation around its axis, a holding chain 5 at the bottom of the closest V-block pair grasps the drill pipe and thus holds the drill pipe in place. In a corresponding way, a holding chain at the bottom of the furthest V-block pair grasps the drill pipe, but this is blocked from the observers view by the furthest V-block pair 2. With the drill pipe 4 in position in the V-block pairs 1-2 and prevented from rotating by the holding chains 5, the boring head may be twisted loose. The boring head 8 is arranged at the end of the drill pipe and is situated beyond the closest V-block pair 1. A loosening chain 6 is arranged around the boring head 8 and grasps the boring head. Using a hydraulic cylinder the loosening chain 6 may be used to twist the boring head from the drill pipe.

The pipe clamp in the state it is illustrated in figs. 1-2 works well for straight drill pipes of even thickness, but drill pipes often have sections of varying sizes and each section may have a diameter that varies along its extent. If such a drill pipe is placed in the pipe clamp, the pipe clamp will not achieve a good grip on the pipe and the pipe may end up in a tilted position. If the loosening chain 6 is activated using the hydraulic cylinder when the pipe sits in a tilted position in the pipe clamp, loosening of the boring head may be impossible or the threads of the boriung head may be damaged.

Fig. 3 shows the pipe clamp from its wide side with both V-block pairs 1-2 in a nominal position. With the V-block pairs 1-2 in the nominal position, a pipe placed in the V-block pairs is supported from below along the longitudinal axis of the pipe clamp at four different places along its longitudinal extent. The pipe clamp is designed such that its geometrical longitudinal axis coincides with the direction of extend of the pipe, with the pipe clamp in its nominal position. It comes natural to design the pipe clamp this way, but by the longitudinal axis of the pipe clamp is generally meant the longitudinal axis of the pipe, with the pipe clamp in this nominal position.

Fig. 4 shows the pipe clamp from its wide side with the right V-block pair raised from its nominal position. The right V-block pair has thus been translated orthogonally from the longitudinal axis of the pipe clamp. With the V-block pair elevated in this fashion, the pipe clamp may hold in position a pipe with varying pipe diameter along its longitudinal extent. With such an elevation from the nominal position the pipe clamp may grasp a pipe with a smaller diameter at the right V-block pair than at the left V-block pair 2. The left V-block pair may in a corresponding fashion be lowered from its nominal position in order to grasp a pipe with a larger diameter at the right V-block pair 1 than at the left V-block pair 2.

In the presented embodiment, such a translation opportunity is available only at the right V-block pair 1, but versions of the invention are conceivable where translation of both V-block pairs is possible. The drill pipe itself may be intentionally bent or bent as a result of damage. If a bent drill pipe is placed in the pipe clamp, the pipe clamp will get a bad grip on the pipe and the pipe may end up in a tilted state. If the loosening chain 6 is activated using the hydraulic cylinder when the pipe is tilted in the pipe clamp the head will, during loosening of the head, be pushed in a radial direction which may damage the boring head or make loosening of the boring head impossible. In order to grasp bent pipes, it must be possible to angle at least one of the V-block pairs from the nominal state, and this version is described in conjunction with fig. 5. Fig. 5 shows the pipe clamp from its wide side with the right V-block pair 1 maximally angled counter clockwise from its nominal position, which here is approximately 10°. The bent portion of the pipe is positioned between the V-block pairs such that the portions of the pipe that rests in respective V-block pair is straight or nearly straight.

In the disclosed embodiment, the drill pipe is held in position in V-blocks and is held firm in this position by chains. Obviously, the drill pipe may be held in position in differently designed positioning elements and may be held in place in the positioning elements using holding elements other than chains. The pipe clamp may, as described here, be used for grasping a drill pipe, but may obviously be used for grasping other elongated elements. These elongated elements do not have to be hollow pipes, but may be solid and correspondingly, the concept of pipe clamp is in no way intended as a restricted to devices grasping pipes in particular, and the phase is here intended to include clamps that may grasp any type of elongated element.

In the disclosed embodiment, the drill pipe is held in position in two V-block pairs, but in principle the drill pipe may be held in position in more than two V-block pairs and potentially by one V-block pair if the drill pipe receives further support by some other element. The V-blocks do in the disclosed embodiment occur in pairs, which is suitable as each pair gives a well defined direction to the respective pipe section each V-block pair supports and the pipe section may then simply be held down against the V-block pair using for example and holding chain 5 placed between the V-blocks in the V-block pair. In principle there is though nothing preventing the V- block from not being used in pairs.