GB2074629A

GB2074629A - Drilling rod system for a sinking drilling tool

Info

Publication number: GB2074629A
Application number: GB8105154A
Authority: GB
Original assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Current assignee: Salzgitter Maschinen und Anlagen AG; Salzgitter Maschinen AG
Priority date: 1980-04-24
Filing date: 1981-02-18
Publication date: 1981-11-04
Also published as: GB2074629B; SE8100631L; AT371562B; ES265238Y; ATA44681A; ES265238U; DE3015695A1; FR2481358A1

Abstract

A drilling rod system for a borehole comprises an outer pipe (6), an intermediate pipe (19), and an inner pipe (28). A driving medium is fed to the drilling tool through the passage (34) within the inner pipe, and is returned after use through the passage (29) between the inner and intermediate pipes. A flushing medium is supplied to the tool through the passage (20) between the intermediate and outer pipes. The three pipes (6, 19, 28) are held fixedly spaced from one another by spacers along their length, e.g. studs (16) held in a cage (13) between outer pipe (6) and intermediate pipe (19), and protuberances (30) between intermediate pipe (19) and inner pipe (28). Spacer plates or balls may alternatively be used. <IMAGE>

Description

SPECIFICATION Drilling rod system for a sinking drilling tool This invention relates to a drilling rod system for a sinking drilling tool, for example a sinking drilling hammer or a sinking drilling turbine, arranged to travel within a borehole, the system comprising an outer pipe, two conduits arranged within the outer pipe, and three passages within -the outer pipe, with a driving medium being fed to the drilling tool through one of the passages and being returned again after utilisation through a second of the passages, and with a flushing medium being fed to the drilling tool through the third passage.

One known unitary drilling rod of this type (West German published patent application 1091507) is used for the connection of a pneumatic sinking impact hammer. Within the outer pipe is arranged an intermediate pipe, creating an annular outer passage therebetween, and within the intermediate pipe there is an inner pipe, creating an annular intermediate passage therebetween, and the inner pipe encloses an inner passage. The outer pipe is joined on the one hand to a take-off shaft of a rotary drilling machine which remains outside the borehole and on the other hand to the pneumatic impact hammer. The inner passage carries pressurised air to the impact hammer, the annular outer passage takes away the used air, and the annular intermediate passage carries flushing fluid to the working region.The removal of the flushing medium and of the drillings takes place between the outer pipe and the wall of the borehole. The passages are respectively connected by means of a plate equipped with ports to connecting bores of the take-off shaft and of the impact hammer. From each plate there extends a ring which positions the inner pipe and the intermediate pipe relative to one another and relative to the outer pipe. Neither the inner pipe nor the intermediate pipe is supported or positioned over their remaining length, so that the working length of the drilling rod is limited and its weight is comparatively high on account of the thickness of the walls needed for the inner pipe and intermediate pipe in order that they shali have sufficient strength.

It is an object of the present invention to provide a drilling rod system, possibly made up from a number of extension drilling rods, which has sufficient strength but which is comparatively light, and in which above all the conduits are maintained at least approximately spaced constantly from one another and from the outer pipe and in which, consequently, symmetrical flow conditions in the drilling rod system can be ensured.

This is achieved in accordance with the present invention in that the outer pipe and the two conduits are held each respectively spaced from one another by spacing means distributed along their length.

The reduced wall thickness of the two conduits which is thus made possible creates a larger flow cross-section for the same external diameter of the drilling rod system in a most desirable way.

The relative positioning of the conduits and of the outer pipe is ensured over the whole length of the drilling rod system. The assembly of the individual drilling rods or of the extension drilling rods is considerably simplified. The flushing medium and the drillings can here also be extracted through the annular space between the outer pipe and the wall of the borehole.

According to one preferred embodiment of the invention the two conduits are formed as an intermediate pipe and as an inner conduit arranged within the intermediate pipe. Preferably, the inner conduit likewise consists of a pipe.

According to a further preferred embodiment of the invention, the spacing means acting between the intermediate pipe and the inner conduit comprise local protuberances formed in the material of the intermediate pipe. By using an intermediate pipe with a comparatively thin wall thickness these protuberances can be produced with little cost and with a high degree of accuracy.

No separate and additional spacing elements are then necessary to achieve the relative positioning of the intermediate pipe and of the inner conduit.

In the assembly process, the inner conduit can be simply and quickly inserted into the intermediate pipa.

According to another preferred embodiment of the invention, the spacing means acting between the outer pipe and the intermediate pipe comprise elements held in position by a cage. These elements can be manufactured for example from a polyamide material, and the cage can be tubular and made from steel sheet or polyvinylchloride.

A particularly simple assembly with secure positioning can be achieved if, in accordance with a preferred feature of the invention, each of these elements is formed in the manner of a stopper having one part of comparatively small crosssectional surface area which extends from the outside in through a hole in the cage and into contact with the intermediate pipe.

According to another embodiment of the invention each of these elements is formed as a ball. In this case, as well as having a simple assembly, the fluid flow conditions within the drilling rod system are comparatively favourable.

Particularly low manufacturing costs are encountered if, according to another preferred embodiment of the invention, the spacing means acting between the outer pipe and the intermediate pipe are formed as bodies, for example balls or conical elements, held in position by depressions in the intermediate pipe. The concave depressions defined by the rear surface of the aforementioned protuberances of the intermediate pipe can serve for this purpose for example.

According to another preferred embodiment of the invention, the two conduits may be formed as pipes extending parallel to one another.

A preferred embodiment of the invention has the spacing means comprising a plurality of axially spaced plates equipped with axial ports. Each plate can be secured either to the associated intermediate pipe, or to the associated inner conduit, or to the two parallel pipes, as the case may be. Each plate may also be provided with a projecting lug which is arranged to engage in a recess of an adjacent pipe so that in this way the plates are positioned correctly in the axial direction.

Especially favourable weight ratios can be achieved if, according to another preferred embodiment of the invention, the inner conduit is formed as a hose. The hose can be made resistant to compression as required.

In yet another embodiment of the invention a socket is provided at the one end of the drilling rod or at one end of each extension drilling rod of the drilling rod system on the end of each of the two conduits, and a spigot carrying the corresponding conduits of an adjacent extension drilling rod or of a terminating element is sealingly inserted into the socket. Such terminating elements can be for example a connector head with passageways for the driving medium and for the flushing medium for the sinking drilling tool The joint can in every case be effected by a tapered screw connection with the adjacent outer pipe of the drilling rod system. This ensures a simple, quick and reliable coupling to either of the parts of the drilling rod system to one another and to the terminating elements.

According to a preferred embodiment of the invention, in which the conduits are coaxial pipes, an inner socket of the inner conduit is arranged within and spaced from an intermediate socket of the intermediate pipe, and an annular passage between the outer pipe and the intermediate pipe is connected by way of ports in a wall of the intermediate socket with a corresponding annular passage of an adjacent extension drilling rod or of the terminating element.

In yet a further embodiment of the invention, where the two conduits are formed as parallel pipes, they may be fitted with sockets which are connected to a common socket member rotatably inserted into the outer pipe, such that the passage between the parallel pipes and the outer pipe is connected to the corresponding passage of an adjacent extension drilling rod or of the terminating element by means of ports in that socket member.

Although for the purpose of describing the invention reference is made herein to the use of three passages within the outer pipe, the invention is also applicable with equal validity to a drilling rod system in which more than three passages extend through this outer pipe.

In order that the invention may be fully understood, a number of embodiments of drilling rod system in accordance with the invention will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a side view, turned through 900; of a hammer drill located in a borehole and fitted with extension drilling rods; Figs. 2 to 4 together make up a longitudinal sectional view through one of the extension drilling rods shown in Fig. 1, on an enlarged scale; Fig. 5 is a sectional view taken along the line V-V in Fig. 3; Fig. 6 is a cross-sectional view through half of a further embodiment of extension drilling rdd; Figs. 7 and 8 are cross-sectional views, respectively showing two quarters of further embodiments of extension drilling rod;; Fig. 9 is a longitudinal sectional view through a socket end of yet another embodiment of extension drilling rod; Fig. 10 is a longitudinal sectional view through the spigot end of the extension drilling rod shown in Fig. 9; Fig. 11 is a sectional view taken along the line Xl-Xl in Fig. 9; Fig. 12 is a sectional view taken along the line Xll-XIl in Fig. 9; Fig. 1 3 is a longitudinal sectional view through a part of a joint between two further embodiments of extension drilling rod; Fig. 14 4 is a longitudinal sectional view through a part of a joint between two more extension drilling rods; and, Fig. 1 5 is a sectional view taken along the line XV-XV in Fig. 14.

Fig. 1 is a representation, turned through 900, of a hydraulic earth-drilling hammer 2 positioned in a borehole 1 and having an extension drilling rod assembly 3, comprising extension drilling rods 4 and 5, secured to it.

Figs. 2 to 5 show individual features of the extension drilling rod 4.

As shown in Fig. 2, a terminating socket 7 having a tapering internal screw-thread 8 is welded into the end of an outer pipe 6 of the extension drilling rod 4. As is shown in Fig. 4, a terminating spigot 9 with a complementary tapering external screw-thread 10 is welded into the opposite end of the outer pipe 6. Between the internal end face 11 of the terminating socket 7 (Fig. 2) and the internal end face 12 of the terminating spigot 9 there extends a cage 13 formed as a thin-walled steel tube which is provided with apertures 14 (Fig. 3 and Fig. 5) through which the smaller diameter portion 1 5 of a stepped plug-like stud element 1 6 projects. The larger diameter portion 1 7 of the stud element 1 6 lies on the outside of the cage 13 and has a rounded top which constitutes a contact surface resting against the internal wall surface 1 8 of the outer pipe 6.

An intermediate pipe 19 is contacted by the free end face of the smaller diameter portion 1 5 of the stud elements 1 6. The stud elements 1 6 thus serve as distance pieces and define an outer annular passage 20 between the internal wall surface 18 of the outer pipe 6 and the intermediate pipe 1 9. The annular outer channel 20 is connected with the ambient surroundings at the one end by way of an annular chamber 21 in the terminating socket 7 and at the other end by way of a number of circumferentially spaced bores 22, an annular groove 23 and an annular chamber 24 in the terminating spigot 9.

The left-hand end of the intermediate pipe 1 9 projects outwardly beyond the end of the terminating socket 7, as can be seen from Fig. 2.

Fig. 4 shows, inter alia, an intermediate pipe 19' of the adjacent extension drilling rod 5, whose left-hand end, sealed by a sealing ring 25, is inserted into an intermediate socket 26 of the 'terminating spigot 9. As shown in Fig. 3 this intermediate socket 26 is welded to the right hand end of the intermediate pipe 1 9.

As can also be seen from Fig. 3, the cage 13 is also perforated by a number of holes 27 which permit a practically unhindered fluid flow exchange to enable the complete filling of the annular outer passage 20 on both sides of the cage 1 3. These holes 27 are provided in sufficient number and with an appropriate distribution to achieve this.

Within the intermediate pipes 1 9, 1 9' are arranged respective inner pipes 28 and 28'.

Respective annular inner passages 29 and 29' are thereby defined between the intermediate pipes 19, 19' and the inner pipes 28, 28'. For this purpose protuberances 30, 30' are formed in the material of the intermediate pipes 19, 19' projecting inwardly and acting as spacing elements holding the intermediate pipes away from the inner pipes. As is shown in Figs. 2 and 4, the left-hand end of each inner pipe 28, 28' projects to the left beyond the left-hand end of the associated intermediate pipe 1 9, 1 9', Fig. 4 shows how the left-hand end of the inner pipe 28', sealed by a sealing ring 31, is introduced into an inner socket 32 positioned within and spaced from the intermediate socket 26.Again as shown in Fig. 4, the right-hand end of the inner pipe 28 is welded to the inner socket 32. The annular inner passage 29 is in permanent fluid communication with the annular inner passage 29' by way of an annular chamber 33 which is defined between the intermediate socket 26 and the inner socket 32.

The respective inner pipes 28, 28' enclose inner passages 34, 34' which, as shown in Fig. 4, are permanently in communication one with another by way of a chamber 35 within the inner socket 32.

The inner pipe 28' is likewise a part of the extension drilling rod 5. For simplification of the drawing the terminating socket of the extension drilling rod 5 which corresponds to the terminating socket 7 shown in Fig. 2 has been omitted from Fig. 4.

Hydraulic fluid under pressure is supplied to the inner passages 34,34' for the driving of the drilling hammer 2 and for the control of its impact mechanism. This hydraulic fluid flows back through the annular inner passages 29, 29' after it has performed its work function. A flushing medium, for example air or water or a mixture of air and water, is supplied through the annular outer passage 20 to a drilling tool 36 (Fig. 1) of the drilling hammer 2. The flushing medium and the drillings are carried out through an annular gap 37 between the wall of the borehole 1 on the one hand and the drilling hammer 2 and the extension drilling rod 3 on the other hand. Fig. 2 includes arrows indicating the respective directions of flow for greater clarity.

In the subsequent description of the other Figures of the drawings those elements which correspond to elements shown in Figs. 1 to 4 are indicated by the same reference numbers.

As can be seen from Fig. 6, between the outer pipe 6 and the intermediate pipe 1 9 there is provided a disc 38 which serves as a spacing element, which extends perpendicular to the longitudinal axis of the extension drilling rod 4, and which is provided with axial ports 39 distributed around its circumference. The disc 38 has a radially inwardly projecting lug 40 which engages in a recess of the intermediate pipe 1 9, this recess being provided by the reverse side of one of the protuberances 30. By means of this lug 40 the disc 38 is secured in place in the axial direction. Depending upon the length of the extension drilling rod 4 a greater or lesser number of such discs 38 may be provided axially spaced from one another along the length of the rod. The flushing medium can pass through the ports 39 practicaily unhindered.The disc 38 is made of a resilient material, so that the projecting lug 40 initially slides along the outside of the intermediate pipe 1 9 in a resiliently doubled-back state, until, when it reaches the desired axial position, it snaps into place in the recess 41 of the intermediate pipe 19.

In the upper and lower halves of Fig. 7 one can see respectively different types of spacer. In the upper half of Fig. 7 the spacing elements are formed as balls 42 which are positioned in contact with the internal wall surface 1 8 of the outer pipe 6 and which are held in position by the recesses 41 in the intermediate pipe 1 9. For example, one can have four such balls 42 equally spaced around the circumference, corresponding to the stopper like stud elements 1 6 shown in Fig. 5.

The lower half of Fig. 7 shows the use of substantially conical bodies 43 instead of balls 42.

Each of these conical bodies 43 has a rounded apex which is seated in one of the recesses 41 in the intermediate pipe 1 9 and a rounded cylindrical external surface which is rounded to match the internal wall surface 1 8 of the outer pipe 6 and which rests against this internal wall surface.

Again, in Figure 8, the upper and lower halves of the drawing illustrate different forms of spacing element. In each of these embodiments spacing elements in the form of balls 44 are used which lie outside the intermediate pipe 1 9 and which contact the internal wall surface 1 8 of the outer pipe 6. In the upper half of Fig. 8 the balls 44 are maintained in position by a cage 45 of plastics material which extends approximately down the centre of the annular outer passage 20. In the lower half of Fig. 8 the positioning of the balls 44 is effected by a tubular cage 1 46 of plastics material which lies in contact with the intermediate pipe 19. In both cases holes are provided in the cages 45, 46 to receive and seat the balls 44.Moreover, in the case of the cage 45, further holes 27 are provided through the cage to permit the passage of the flushing medium.

In the embodiment shown in Figs. 9 to 12 two pipes 47, 47' and 48,48' are arranged parallel to each other and parallel to the outer pipes 6, 6', and within the outer pipes 6, 6' of the extension drilling rods 4, 5. As shown in Fig. 9, the pipes 47, 48 are welded adjacent to their right-hand ends to a socket member 49 which is set rotatably into the outer pipe 6. The pipes 47,47' and 48, 48' are seated within and guided through spacing elements here formed as plates or discs 50, and are secured to these discs, for example by welding. One such disc 50 is shown in Fig. 9.The discs 50 are supported for rotary movement against the internal wall surface 1 8, 1 8' of the outer pipes 6, 6'. As shown in Figs. 9 and 11, the discs 50 have axial ports 39 for the passage of that medium which flows in the passages 51, 51' between the pipes 47, 48 and 47', 48' and the outer pipes 6, 6'.

The socket member 49 is also provided with bores 54 and 55 in the right-hand end face 56 and in alignment with the respective pipes 47 and 48.

The bores 54, 55 are fitted with internal circumferential sealing rings 52 and 53 respectively. The socket member 49 is also provided with ports 57 which provide for fluid communication between the passages 51 and 51'.

As can be seen from Fig. 10, the left-hand ends of the pipes 47', 48' are fixed in a support member 58 which is freely rotatably mounted in the outer pipe 6' and has ports 59 therethrough which connect the ports 57 and the passage 51 with the passage 51'. This communication is aided by an annular groove 60 in the outer pipe 6' which, as is shown by the chain-dotted line indicating the fitted end position of the end face 56 of the socket member 49, remains free even when outer pipe 6' is joined to outer pipe 6. In this position the ends of the pipes 47', 48' which are shown as the left-hand ends in Fig. 10 are sealingly fitted into the bores 54, 55 in the socket member 49.

The pipes 48', 48 can serve for example for the supply of the hydraulic pressurised fluid and the pipes 47, 47' for its return, while the passages 51 51 carry the flushing medium, these flows being indicated by the arrows in Fig. 10.

In the embodiment shown in Fig. 13, the internal conduits are formed as hoses 61, 61'. The right-hand end of the hose 61 as shown in Fig. 1 3 is secured by means of a clamp fitting 62 to the socket 32, while the left-hand end of the hose 61' as shown in Fig. 13 is connected by means of a clamp fitting 63' to a spigot 64' which, as is shown in Fig. 13, fits into the inner socket 32. The outer parts of the clamp fittings 62, 63' contact the internal surfaces of the intermediate pipes 19, 19' and include axial ports or passageways 65, 66' for the particular medium flowing in the annular inner passages 29, 29'.

The spacing elements acting between the intermediate pipes 1 9, 19' and the outer pipes 6, 6' are formed as annular discs 67 which are secured to the intermediate pipes 1 9, 19' and are provided with axial passageways 68 for the medium flowing in the annular outer passages 20, 20'. Also a spigot 69' for the left-hand end of the intermediate pipe 19' as shown in Fig. 1 3 is equipped with such axial passageways 701f According to the embodiment shown in Figs. 14 and 15, spacing elements are provided acting between the inner pipes 28, 28' and the intermediate pipes 1 9, 19' and these are formed as discs 71,71' fitted to the inner pipes 28,28'.

These discs 71, 71' contact the intermediate pipes 19, 19' and are provided with axial passageways 72, 72' for the medium flowing in the annular inner passages 29, 29'.

Fig. 15 shows one each of the annular discs 67' and 71', each with the appropriate axial passageways 68' and 72'.

Claims

1. A drilling rod system for a sinking drilling tool arranged to travel within a borehole, the system comprising an outer pipe, two conduits arranged within the outer pipe, three passages within the outer pipe, with a driving medium being fed to the drilling tool through one of the passages and being returned again after utilisation through a second of the passages, and with a flushing medium being supplied to the drilling tool through the third of the passages, in which the outer pipe and the two conduits are held each respectively spaced from one another by spacing means distributed along their length.

2. A drilling rod system according to claim 1, in which the two conduits are formed as an intermediate pipe and as an inner conduit arranged within the intermediate pipe.

3. A drilling rod system according to claim 2, in which the spacing means effective between the intermediate pipe and the inner conduit comprise protuberances formed locally from the material of the intermediate pipe.

4. A drilling rod system according to claim 2 or 3, in which the spacing means acting between the outer pipe and the intermediate pipe comprise elements held in position by means of a cage.

5. A drilling rod system according to claim 4, in which each of said spacing elements comprises a stopper-like stud having a first portion of lesser corss-sectional surface area which extends radially inwardly through a hole in the cage and into contact with the intermediate pipe.

6. A drilling rod system according to claim 4, in which each of said spacing elements is a ball.

7. A drilling rod system according to claim 2 or 3, in which the spacing means acting between the outer pipe and the intermediate pipe are formed as elements, for example balls or conical members, which are held in position by depressions in the intermediate pipe.

8. A drilling rod system according to claim 1, in which the two conduits are formed as parallel pipes.

9. A drilling rod system according to any preceding claim, in which said spacing means comprises a plurality of plates equipped with axial ports and spaced along the length of the drilling rod system.

10. A drilling rod system according to claim 9, in which each plate is secured to one or both of the conduits.

11. A drilling rod system according to claim 9, in which each plate has a projecting lug engageable in a recess of an adjacent pipe.

12. A drilling rod system according to any of claims 2 to 7 or any of claims 9 to 11 when dependent on any of claims 2 to 7, in which the inner conduit is formed as a hose.

1 3. A drilling rod system according to any preceding claim, in which a socket is arranged at the one end of the drilling rod or at one end of each extension drilling rod of the drilling rod system on the end of each of said two conduits, and in which a spigot carrying the corresponding conduits of an adjacent extension drilling rod or a terminating element is sealingly inserted into said socket.

14. A drilling rod system according to claim 13, in which the conduits are coaxial pipes, in which an inner socket of the inner conduit is arranged within and spaced from an intermediate socket of the intermediate pipe, and in which an annular passage between the outer pipe and the intermediate pipe is connected by means of ports in a wall of the intermediate socket with a corresponding annular passage of an adjacent extension drilling rod or of the terminating element.

1 5. A drilling rod system according to claim 14, in which a sealing region of the inner socket is arranged axially spaced from the sealing region of the intermediate socket.

1 6. A drilling rod system according to claim 13, in which the two conduits are formed as parallel pipes having sockets which are joined to a common socket member rotatably inserted into the outer pipe, in which the passage between the parallel pipes and the outer pipe is connected to the corresponding passage of an adjacent extension drilling rod or of the terminating element by means of ports in the socket member, and in which the spacing means are rotatable within the outer pipe.

17. A drilling rod system substantially as hereinbefore described with reference to the accompanying drawings.