EP0324870A1 - Self-steering drill string pipe for rotating drill strings of rock drilling machines - Google Patents

Abstract

In a self-steering drill string pipe (1) for rotating drill strings of rock drilling machines which has an inner drilling shaft (2) with a flushing channel (4), which inner drilling shaft (2) can be connected to the drill string and the drilling tool, and a housing (10) which is mounted on this drilling shaft (2) in such a way as to be rotationally movable about the drilling shaft (2) and on which swing-out control strips (11-14) are arranged on the outside and in which the parts of the hydrostatic drives (24) acting on the control strip as well as the electronic (20) and electric control system are accommodated, the power requirement being produced by the rotary movement during the drilling operation, provision is made according to the invention for an annular space (26) to be present between the drilling shaft (2) and the housing (10), which annular space (26) has a radial connection (27) to the flushing channel of the drilling shaft and is closed off at both ends by one rotary non-return valve (28, 29) each sealing against the borehole flushing fluid, and for the annular space (26) to serve as a tank for the working fluid of the hydraulic system, which working fluid is formed by the borehole flushing fluid.

Description

The invention relates to a self-controlling drill pipe for rotating drill pipes according to the preamble of patent claim 1.

The self-controlling drill pipe according to the invention is arranged behind the drilling tool and generally in the vicinity thereof. Its inner drilling shaft is connected in a rotationally fixed manner, in particular to the deepest drill pipe and to the drilling tool. For example, a drill head equipped with several roller drill bits serves as the drilling tool. As a result, the self-control works immediately behind the free cutting of the drilling tool, whereby the correction of any deviation of the drilling tool from the predefined drilling direction is carried out so quickly that the direction of the drilling practically coincides with the desired direction. The self-control required for this is accommodated with its various systems in the standing housing, which encloses the drilling shaft. On the outside, the housing carries the control strips, which are offset by the same arc angle and pivotally mounted at one end, which, in cooperation with the joint of the borehole, apply the necessary correction forces. In the housing there are recesses in which the measuring device designed as an inclinometer Value transmitter, the system used to drive the control strips, which can swivel out the control strips individually depending on the respective deviations, as well as the control and, if necessary, special electronics which act on a measured value pressure pulse generator, which transmits data to the drilling rig via the borehole flushing . The stator of a generator that generates the electrical energy for the electronics and electrics is also accommodated in the housing.

In general, the chambers are placed one behind the other in radial projections of the standing outer body, which are housed behind the rod-side end mounted and connected to the travel limiter end of the housing connected to the travel limiter. This results in a space-saving arrangement, which pipe rods for bores with a relatively small diameter of e.g. 21.6 cm allows.

In general, the rotating drill pipe, with which the self-controlling drill pipe according to the invention is used, is driven by a drill motor installed outside the drill hole. Rotary drilling Working rock drilling machines produce boreholes sunk from top to bottom, in which the borehole flushing serves to discharge the cuttings removed from the bottom of the borehole with the drilling tool upwards and out of the borehole. Such a flushing can also be operated with water in the device according to the invention with sufficient buoyancy speed in the borehole, but weighted flushing fluids which generate additional buoyancy and are known for this purpose are known as a gel or as a cloudiness with tixotropic properties, for example when bentonite is present. Since gravity supports the discharge of the cuttings from the borehole when drilling from bottom to top, the device according to the invention can also be used for such bores, provided that rinsing liquids are used here, for example, to cool the cutting edges.

The borehole slurry flowing in the area between the pipe string and the borehole joint can be used for the transmission of measured values. Part of the electrical system then serves to hydraulically control the pressure pulse generator, which is mounted in the shaft and changes the cross section of the flushing channel. Here, however, the hydraulic Control of the encoder can be installed in the outer body.

In such self-controlling drill pipes, because of the largely miniaturized hydraulics due to the limited space available in the housing, it is necessary to make high demands on the cleanliness of the hydraulic working fluid and also the mechanical parts, which, like the bearings of the drilling shaft, are particularly sensitive to the ingress of cuttings are to protect.

The invention is based on a known self-controlling drill pipe of the type described at the beginning (Glückauf magazine 120 (1984) No. 13, pp. 819,822). One of the chambers mentioned serves as a tank for the hydraulic working fluid consisting of oil for the hydraulic pumps for the pistons housed behind each control bar in the linkage. The pumps represent the system's pressure generators and are mechanical, ie driven by an eccentric of the drilling shaft. The hydraulic control of the pressure pulse generator requires a series of rotary unions of the drilling shaft in the housing, which are provided with soft seals sealed on the drilling shaft, which seal the working fluid of the hydraulic system, which is under a system pressure of, for example, 100 bar. In the The radial bearings of the drilling shaft are located at the ends of the housing and are supplemented by an axial bearing which is arranged behind the radial bearing on the drilling tool side in the housing. These drilling shaft bearings are designed as roller bearings in order to achieve a smooth shaft in the housing. To protect the drill shaft bearings, rotary seals are attached to the front of the housing, which separate the bearing lubrication from the borehole slurry and relieve the soft seals.

On the one hand, the described construction of these seals is complex and prone to failure due to the large number of their components. On the other hand, the sealing pressure of the rotary seals is not sufficient for the high pressures of the borehole flushing, as are encountered in deep boreholes that have to be sunk over several hundred or even a thousand meters. The sealing rings of the rotary bearings must be insulated. Nevertheless, even at low depths, a wedge of lubricant forms between these surfaces of the rotary seals that rub against each other. Even with the most careful storage, the drilling shaft and the housing execute radial movements, which also act on the surfaces of the rotary seals, which are sealed and lubricated. This will make the finest cuttings from the drill Hole flushing drawn into the lubricant part mentioned. These particles have an abrasive effect on the polished, rubbing surfaces of the rotary seal. As a result, parts of the cuttings get between the drilling shaft and the housing. They destroy the shaft bearings in a short time and also attack the generator, hydraulic pumps and the soft seals of the rotating unions. Damaging or destroying these parts is particularly dangerous because it can result in the loss of oil as a working fluid. The total amount of oil available is very small, so even small oil losses can cause the entire system to fail. In addition, contamination of the oil leads to considerable malfunctions in the downstream hydraulic assemblies of the system.

If such disturbances occur, they take place with changing depths in increasingly shorter periods of time. They can only be removed from the removed device. This requires the entire pipe string to be pulled out of the borehole. The periods of time lost as a result of this and due to the re-insertion of the pipe linkage are not acceptable if their frequency does not match the periods of time, which are necessary for the replacement of worn drilling tools.

The invention has for its object to simplify the structure of the self-control in a self-controlling drill pipe with the features explained above and to ensure that regardless of the pressure of the borehole flushing and thus of the depths drilled holes the service life of the parts important for the system in any case turns out large that it is not less than the service life of the drilling tools.

This object is achieved by the invention with the features of claim 1. Appropriate embodiments are the subject of the dependent claims.

According to the invention, the hydraulic differential pressure which prevails between the drill pipe rinsing in the rinsing channel of the drilling shaft and the borehole rinsing at the respective end of the housing is used as a working medium of the hydraulic system by branching off a partial flow of the rinsing liquid which is largely free of the drilling cuttings and which flows in to prevent contaminated flushing liquid from the borehole into the housing. This differential pressure namely creates a pressure gradient from the annulus into the borehole so that no cuttings can flow back. On the other hand, this pressure drop is relatively small, so that there are also small pressure differences in front of and behind the check valves separating the clean drilling fluid from the contaminated drilling fluid, which considerably simplifies the construction of such valves.

In addition, the invention uses the relatively clean drill pipe drilling as a working fluid hydraulic system of self-control, which u. a. does the necessary work in the drives of the control strips. This enables self-control to be achieved with a simplified hydraulic system, even for very deep bores with correspondingly high hydraulic pressures. The rotary unions described are namely outside under the high hydraulic pressure of the flushing and inside under the system pressure, so that low differential pressures result in deep bores and the soft seals can also be used for this.

It has been found that in spite of the sensitive components of the hydraulic system of self-control, in addition to rinsing from water or gels, tixotropic slurries as working rivers liquid are suitable if they are separated before drilling the borehole and are therefore essentially free of cuttings. All types of irrigation are enriched with parts of the cuttings over the duration of their use in the irrigation circuit. Since, however, according to the invention only a partial flow of the fresh, ie the drill pipe rinse, branches into the annular space, it can be counteracted by dangerous contamination of the hydraulic working fluid. Although the drilling of the borehole in the borehole is still on after pulling the pipe string, the check valve's built-in check valves can also be used to maintain the fluid filling of the annular space, which prevents the penetration of cuttings.

This also makes it possible to include the bearings in the drill pipe irrigation of the annular space and to cool them with this liquid. The check valves mainly act as dirt deflectors on the cuttings of the borehole slurry.

According to the features of claim 2, one also uses the clean drill pipe winding for driving the pulse generator, but generates the required pressure with a pump mechanically derived from the drill pipe. Thereby it is possible to shape the pulses representing the measured values in such a way that they can be read without error by a differential pressure sensor at the mouth of the borehole.

The above-mentioned possibility of using drill pipe rinses contaminated with particles of the cuttings in the manner according to the invention as described above can be realized with the features of claim 3, because suitable filters or filter media are available and provide sufficient service lives so that the regular Removing contaminated filters after pulling the pipe string to replace the drilling tool is sufficient to eliminate this source of interference.

The check valves, which are required at the ends of the housing or the annular space, can be constructed relatively easily. With the features of claim 4, their valve body is formed by a metal ring housed in a standing housing in the groove, which is preloaded, for example, with an annular spring arrangement in the direction of the valve seat, which is axially immovably housed in a groove of the drilling shaft or a drilling shaft flange. Such metal rings are known as seals and for rough operating conditions suitable, such as occur in construction. They are particularly useful as check valves for the purposes of the invention because their spring force is increased by the external pressure of the drilling fluid and because the pressure gradient directed from the inside to the outside ensures that no abrasive particles of the cuttings can get between the mutually projecting surfaces of the metal rings .

• Fig. 1 schematisch und unter Fortlassung der erfindungsgemäßen Einzelheiten eine Gesamtansicht des selbststeuernden Gestängerohres gemäß der Erfindung im Längsschnitt,
• Fig. 2 einen Schnitt längs der Linie II-II der Fig. 1 und
• Fig. 3 schematisch die Ausbildung der Selbst­steuerung gemäß der Erfindung, wobei Teile im Schnitt wiedergegeben und das hydrauli­sche System in Symbolen gezeichnet ist.

The details of the invention are explained below with reference to the drawing; show it

• 1 schematically and omitting the details according to the invention, an overall view of the self-controlling drill pipe according to the invention in longitudinal section,
• Fig. 2 shows a section along the line II-II of Fig. 1 and
• Fig. 3 shows schematically the formation of self-control according to the invention, parts shown in section and the hydraulic system is drawn in symbols.

1, the self-controlling drill pipe, generally designated (1), is provided with a drilling shaft (2) which is screwed to the end of the last drill pipe of a rotating pipe rod via a threaded head (3), which is common in drill pipes of rotary drilling rigs can be. The drilling shaft (2) has a rinsing channel (4) which extends to the other shaft end (5) with an enlarged diameter, which, with its internal thread (6), receives the threaded pin (not shown) of a drilling tool which consists of several tapered rollers fitted with hard metal chisels consists.

The drilling shaft is surrounded by a housing (10). On the outside of the housing are U-shaped profiled control bars (11-14), each offset by a quarter circle, with their angled web ends, as shown at (15) in Fig. 1, pivotally mounted. The housing has projections (16-19) enclosed by the U-profiles of the control strips (11-14), in which chambers are recessed. In the chamber shown at (20) in Fig. 1, the control electronics of the self-control is housed protected. In the chamber (21) below there are crosswise oriented inclinometers which indicate the actual values of the inclination of the drill pipe in the borehole. In the one below Chamber (22) of the drive piston assigned to each control strip is guided. The rotor of a generator (22) generating the electrical energy is connected in a rotationally fixed manner to the drilling shaft (2) and works in a stator which is arranged in a rotationally fixed manner in the housing. A hydraulic pump is housed in the chamber shown at (24), while a hydraulic pulse generator is indicated at (25).

In operation, the control strips (11-14) are swiveled out in accordance with the signals coming from the inclinometers at (21) and thereby hold the drill pipe (1) in the specified drilling direction. The electronics convert the measured values into electrical or hydraulic signals, which are implemented by the directional control valves of the hydraulic system or recorded by the pulse generator. This changes the cross-section of the flushing channel and thus generates differential pressures in the drill pipe drilling, which are read at the mouth of the borehole and converted into digital values.

3, an annular space (26) surrounding the drilling shaft (2) is formed between the drilling shaft (2) and the housing (10). It is connected to the drill pipe flushing by means of a radial shaft bore (27) which extends from the annular space into the flushing channel (4) of the drilling shaft (2).

At both ends, the annular space is sealed with a rotary check valve (28, 29) against the drilling fluid (30) flowing between the housing (10) and the borehole joint (29). The borehole mud contains particles released from the drilling tool, not shown in FIG. 3. Between the two rotary seals (28 and 29) are the radial bearings of the drilling shaft (2), shown schematically at (31 and 32). The axial bearing usually provided is not shown in the illustration in FIG. 3 for reasons of simplification. The dirt filter (33) built into the radial bore (7) is shown next to the bore to show the hydraulic system.

In the hydraulic system of self-control, a hydraulic pump is assigned to each bar. It is driven by an eccentric (34) which is fixed in a rotationally fixed manner on the drilling shaft (2) and acts on a pump piston (36) via a self-bearing ring (35). A radial bore (37) connects the pressure chamber of the pump cylinder with the annular space (26), in which the clean drill pipe flushing is applied. Check valves (37, 38) secure the pressure chamber of the pump. The pump acts on an electrically controlled, spring-loaded 2/3-way valve (39) via which the drive piston mentioned in connection with FIG. 1 acts be suggested, which opposite control strips are assigned as rotary actuators and designated (40 and 41). The hydrostatic system is secured by a bypass line (42) secured by a check valve.

In the middle part of Fig. 3, the pulse generator (25) is shown as a double piston, which is mounted in the drilling shaft (2) in a radially movable manner. The soft seals of the rotary unions (43-45) serve to secure the two hydraulic lines (46 and 47) which act on the piston of the pulse generator. This is done via a 2/3-way valve (48) corresponding to the valve (39), which is acted upon by a spring pressure accumulator (49) with the clean flushing liquid, which is supplied by the hydraulic pressure generator via a branch line (50) and a pressure relief valve (51) is acted upon.

As can also be seen from FIG. 3, the check valves (28, 29) are of uniform design. According to the enlarged representation in FIG. 1, they are each in a radial gap (53, 54) between the end face (55, 56) of the housing (10) and a collar (58, 59) of the drilling shaft (2). Each valve is realized with an axially preloaded slide ring (66), which is seated in a bore (64) in a bore (64) Groove (61) of the housing (10) is housed. The annular surface (62) of a metal ring (63), which is immovably fixed in each collar (58, 59) of the drilling shaft (2) in a groove (67) provided there, serves as the valve seat.

The mutually projecting surfaces of the rings serve as dirt repellants because of the pressure gradient directed from the inside outwards. Due to the wedge shape of the sealing gap, the area ratios of the rings are selected so that the ring areas are lifted off one another from the internal pressure which prevails in the annular space as soon as the internal pressure is greater than the external pressure. Therefore drill pipe flushing can overcome the ring surfaces from the outside, but the backflow is excluded.

Claims (5)

1. Self-regulating drill pipe for rotating drill pipes of rock drilling machines, which has an inner drill shaft (2) with flushing channel (4) which can be connected to the drill pipe and the drilling tool (7) and a housing (10) mounted on the drill shaft (2) so that it can rotate about it, arranged on the swivel-out control strips (11-14) and in which the parts of the hydrostatic drives (40, 41) acting on the control strip, as well as the control electronics (20) and electronics (23) are accommodated, the energy requirement due to the rotary movement is produced during the drilling process, characterized in that between the drilling shaft (2) and the housing (10) there is an annular space (11) which has a radial connection (27) to the flushing channel (4) of the drilling shaft (2) and on both Ends each with a rotary check valve (28, 29) sealing against the drilling fluid, and that the annular space (26) serves as a tank for the drilling fluid flushing formed Working fluid of the hydraulic system is used. 2. Self-controlling drill pipe with a pressure pulse generator, characterized in that the drill pipe flushing is used as the hydraulic working medium of the pressure pulse generator (25), the hydraulic working pressure being derived from the hydraulic system for pivoting out the control strips (11-14). 3. Self-controlling drill pipe according to one of claims 1 or 2, characterized in that the radial connection (27) is a bore (27) extending to the flushing channel, into which a filter (33) is installed, which flushes out the flushing channel (4) the drilling shaft (2) is acted upon. 4. Self-controlling drill pipe according to one of claims 1 to 3, characterized in that the check valves (28, 29) at the ends of the outer tube in a radial gap (53, 54) between the end faces (55, 56) of the housing (10) and a collar (58, 59) of the drilling shaft (2) is accommodated, an axially preloaded slide ring (60) in a groove (61) of the housing (10) as the valve and the annular surface (62) of one in the collar ( 58, 59) of the drilling shaft (2) accommodated, axially fixed metal ring (63). 5. Self-controlling drill pipe according to one of claims 1 to 4, characterized in that the pulse generator (25) via a soft seal (43-45) provided with a rotary union from a pressure accumulator (49) which is acted upon by a hydraulic pressure generator (36) is.

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