EP0086701B1 - Drilling device - Google Patents

Abstract

The improvement in the boring devices is adapted to cut grooves or cavities at the bottom of bored holes. It comprises a tool (3) containing a diaphragm (17) forming an expansion chamber to which a liquid under pressure can be supplied for radially displacing cutting elements (24) set with diamonds between a retracted position and a projecting working position. The measurement of the variation of the volume of the liquid under pressure in a chamber (26) enables the radial position of the elements (24) to be known.

Description

The present invention relates to an improvement to drilling devices and is particularly applicable to drilling in the ground, rock or concrete.

Known drilling devices, whether with drill bit, drill bit or drill bit, make it possible to drill holes having a constant section and therefore having a cylindrical inner wall. However, it is often desirable to be able to increase the diameter of the hole at one or more locations remote from the mouth thereof and in particular at the bottom of the hole. Such an increase in diameter, producing a local excavation, is for example useful when it is desired to increase the collection surface of a well bottom, or else when it is simply desired, in holes intended to receive piles, tie rods, dowels, etc., improve the anchoring of the element in the hole.

Tools for increasing the diameter of a well bottom are already known, which tools have a cylindrical shape with elements that can be tilted between a retracted position in which they do not protrude outside the cylindrical wall of the tool and a position emerging in which they emerge from this wall and allow, thanks to the rotation of the tool, to dig a circular groove in the wall of the hole. The tilting of these elements between the retracted position and the emerging position is ensured by means of individual jacks (GB-A-1 602 317) or a central plunger mechanically connected to said elements and whose axial position determines the tilting angle elements.

Such a device is however quite complex and does not lend itself to miniaturization. In addition, the mechanical connection between the elements and the plunger may be subject to jamming or poor distribution of forces. In addition, the tilting element does not work under the same conditions as it tilts, which influences both the characteristics of the work and the geometry of the recess obtained.

It has also already been proposed tools provided with expandable digging elements between a retracted position and an emerging position relative to the generally cylindrical surface of the tool, thanks to a pneumatic actuation. However, such an arrangement also has drawbacks. In particular, it does not allow proper control of the work which is carried out, it should be recalled, out of the sight of the operator.

Finally, US-A-2 334 788 discloses a drilling device which comprises a tool capable of being inserted into and removed from a hole and includes digging elements capable of being moved between a position retracted inside the cylindrical surface of the tool and an emerging position in which the rotation of the tool causes a groove in the wall of the hole to be hollowed out by said elements, which tool has a radially sealed coaxial membrane expandable, on which the digging elements are arranged and whose expansion causes said elements to pass from the retracted position to the emerging position and vice versa.

In this known device, the interior of the membrane communicates permanently with the part of the hole situated below the membrane, which makes it possible either to cause the mud contained in this part of the hole to flow back towards the interior of the membrane, either to expel from the interior of the membrane washing water which is introduced therein by means of pressurization and which then rises between the wall of the hole and the outer surface of the membrane. Because of this construction, it is impossible to control the volume of wash water that enters and leaves the membrane, and therefore the degree of expansion or contraction of the membrane. Ultimately, this construction also does not allow proper control of the work which is performed out of the sight of the operator.

The present invention proposes to remedy the drawbacks mentioned above and relates to a drilling device of the type which comprises a tool capable of being inserted into and removed from a hole and includes digging elements capable of be moved between a retracted position inside the cylindrical surface of the tool and an emerging position in which the rotation of the tool causes a groove in the wall of the hole to be hollowed out by said elements, which tool has a waterproof, radially expandable coaxial membrane on which the digging elements are arranged and the expansion of which causes said elements to pass from the retracted position to the emerging position and vice versa, characterized in that the interior of the membrane is closed, in operation, excluding its communication with a conduit connecting the interior of said membrane to a source of liquid pressurized by appropriate means.

Since the interior of the membrane is closed, the movement of the liquid column between it and the source of pressurized liquid makes it possible to control the degree of expansion or contraction of the membrane and consequently the effective work of the digging elements.

It should be noted that document US-A-2 438 673 describes a device, intended to scrape the internal wall of a casing or a well, in which washing water introduced under pressure into the tool s 'escapes from the base of the tool, by establishing in it a back pressure which tends to push individually scraping tools outwards.

Preferably, the digging elements, produced for example in the form of bars or diamond sectors, are distributed equiangularly around the membrane and these elements are advantageously mounted on metal sectors whose internal wall is in contact with the wall outer of the membrane so that the expansion of the membrane causes a radial displacement of said sectors, and consequently of the digging elements which they support while the retraction of the membrane causes their withdrawal in the retracted position.

Preferably, the body of the tool provides radial guide means for the digging elements and / or for said sectors which support these elements. These guide means can be composed of simple grooves in the cylindrical wall of the tool.

It should however be understood that it is not absolutely essential to have guiding means in this form and the cylindrical wall of the tool may be locally absent at the level of said digging elements.

In a particularly advantageous manner, the membrane, produced for example from an elastomer such as neoprene, can be in the form of a cylindrical jacket, the two ends of which are crimped or clamped suitably between the body of the tool and crimping parts. , one of said crimping parts being provided with a channel for the passage of the liquid between the liquid supply pipe and the interior of the membrane which forms the expansion chamber.

According to an advantageous characteristic of the invention, the device comprises, far from the tool, a liquid chamber in which it is possible to measure either visually or by any other means, the variation in volume of liquid in the chamber which reflects the variation in volume of the membrane and consequently the distance of the radial displacement of the digging elements. It is thus possible at all times to know what is the exact geometrical conformation of the tool and therefore the diameter of the groove being dug. The device can also include a manometer or any pressure indicator making it possible to check if there is no leak, which makes it possible to be sure that the variation in volume of liquid observed does correspond to a radial displacement of the elements of digging.

The means for establishing the pressure may advantageously consist of a compressor, which may preferably be reversible so as to establish, at the end of actuation, a vacuum which causes the retraction of the membrane and, consequently, the withdrawal of the elements of digging.

However, as a variant, this retraction can also be ensured by elastic means, which may possibly be constituted by the elasticity of the membrane or by auxiliary means, making it possible to return the membrane and the digging elements to their initial retracted position when the pressure has decreased sufficiently in the chamber limited by the membrane.

• La figure 1 représente une vue schématique, en coupe selon la ligne I-I de la figure 2, d'un dispositif de forage selon l'invention.
• La figure 2 représente l'outil en position rétractée, en coupe schématique selon la ligne II-Il de la figure 1.
• La figure 3 représente les éléments de la figure 2 à l'état expansé.

Other advantages and characteristics of the invention will appear on reading the following description, given by way of nonlimiting example and referring to the appended drawing in which:

• FIG. 1 represents a schematic view, in section along line II of FIG. 2, of a drilling device according to the invention.
• FIG. 2 represents the tool in the retracted position, in diagrammatic section along line II-II of FIG. 1.
• Figure 3 shows the elements of Figure 2 in the expanded state.

The device according to the invention as described in the example, comprises at the end of an elongated cylindrical rod 1, provided over its entire length with a central passage 2, a tool 3 screwed onto the end of the rod 1, thanks to a thread 4. Upwards the rod 1 continues to a second end by which it is mounted on motor means making it possible to rotate it around its axis, inside a cylindrical hole of slightly larger diameter, previously drilled, and which shows the cylindrical wall 5 and the bottom 6.

The tool 3 itself is presented in a cylindrical outer space having the same diameter as the rod 1, the part of the tool 3 screwed on the rod 1 extending downwards by three arms 7 delimiting between them fe · .tes elongated 8 arranged around a votu '.e interior 9. The three lower ends of the arms 7 have a notched portion 10 which is received in a corresponding groove of an end piece 11, in which it is held by suitable rings. The part 11 has a frustoconical central passage 12 while the tool 3 also has a recess having, towards the volume 9, a frustoconical bearing 13 which tapers downwards.

Inside this passage is screwed a crimping tip 14 thanks to a suitable thread 15, this tip extending by a frustoconical bearing 16 corresponding to the bearing 13. It is thus possible to come crimp or tighten, during screwing of the end-piece 14, a cylindrical elastomer jacket 17, the other end of which is placed around a frustoconical crimping plug 18 which, when it is introduced into the frustoconical passage 12 and advanced downward in this passage thanks to a nut 19 cooperating with its thread 20, makes it possible to tightly crimp the lower end of the membrane formed by the elastomeric jacket 17. The interior 21 of the jacket 17 forms a volume constituting an expansion chamber which is in communication with the passage 2 of the rod 1, thanks to a channel 22 formed in the end piece 14.

Around the jacket 17 are adhered three elongated metal segments 23 on which are fixed and glued digging elements constituted in this case each time by a longitudinal bar forming a diamond sector 24.

At the upper part which emerges from the mouth of the borehole in which the rod is arranged, the end of the rod is preferably connected by a rotating joint, to a conduit for constant volume 25 in communication with the passage 2. The conduit 25 leads to a vertical cylindrical chamber 26 at the upper end of which leads a pipe 27 which, by a valve 28, is connected to a source of air pressure 29 such as '' a compressor or a compressed air tank. A second pipe 30 is connected to a valve 31 to form a vent.

The operation is then as follows: in the absence of air overpressure in the chamber 26, the position of the elastomeric membrane 17 is that shown on the right-hand part of FIG. 1 as well as in FIG. 2. This position is called retracted position and we see that in this position the digging elements 24, which are connected to the membrane 17 via the segments 23, occupy a retracted position in which they do not emerge outside the bulk of the outer cylindrical surface of the tool 3, that is to say outside of the outer surface of the extensions 7. The tool, disposed at the end of the rod 1, can thus be introduced inside a hole whose diameter is very slightly greater than that of the tool and the rod.

It should be understood that the characteristics of the elastic membrane 17 are such that even when the tool is brought into a vertical position at the lower end of the rod 1, the hydrostatic pressure of the liquid contained in the chamber 26, the conduit 25, the passage 2, the channel 22 and the chamber 21, is incapable of exerting a significant deformation of the membrane 17.

Under these conditions, the liquid level is represented by the dashed line 32, most of the chamber 26 then being filled with liquid.

The valve 31 being closed, the valve 28 is then opened and the air pressure in the chamber 26 begins to rise above the liquid surface. This then pushes the liquid towards the chamber 21 where the membrane 17 will then deform by expanding radially outwards, pushing radially outward the segments 23 and the elements 24 which are guided radially by the edges of the extensions 7 which determine the slots 8. If at the same time the rod 1 and the tool 3 rotate around their common axis, it is understood that the digging elements 24, which rotate while rubbing against the wall 5, will dig gradually in this a groove whose cross section corresponds to the part of element 24 which penetrates into the material. In doing so, the liquid level begins to drop in chamber 26.

At a certain moment under the effect of the thrust of the liquid and the digging of the groove, the segments 23 abut against the extensions of the tool 3, so that any further radial expansion is prohibited. This corresponds to the position illustrated on the left in FIG. 1 in which the digging elements 24 are in the extreme emerging position. The chamber 21 then took its maximum volume and the liquid level in the chamber 26 arrived at its lower position represented by 33.

It is clear that, if the position of the level of the liquid in the chamber 26 is identified, for example using a graduation, or by any other means such as a float connected to an indicator system, it is possible to determine the radial outlet distance of the elements 24 from the slots 8, and this at all times during the digging of the groove in the wall 5.

Preferably, the air pressure inside the chamber 26 is constantly displayed by a pressure gauge 34. As long as the pressure gauge 34 displays sufficient pressure, it is certain that there is no leak and that the drop the level of the liquid in the chamber 26 corresponds well to an increase in the value of the volume of the chamber 21 formed by the membrane 17.

When it is desired, at the end of the digging of the groove, bring the digging elements 24 back to their retracted position corresponding to FIG. 2 to allow the extraction of the tool from the hole, the valve 28 is closed and the the valve 31 is opened, which makes it possible to purge the air and thus the elastic return force of the membrane 17 drives the excess liquid out of the chamber 21 towards the chamber 26 in which the liquid level is brought back to its initial position 32. One can then proceed to extract the rod and the tool upwards out of the hole.

As a variant, if the elastic return force of the membrane 17 is insufficient, it is possible to cause the return to the retracted position, for example by means of a spring suitably disposed and which tends to oppose the radial spacing of the segments 23.

In another variant, it is possible to establish a vacuum in the chamber 26 so as to bring the membrane 17 back to its retracted position.

Of course, the invention is subject to various modifications. Thus, instead of providing digging elements 24 in the form of rectilinear bars extending almost over the entire length of the membrane 17, these elements can be replaced by several elements of shorter length axially spaced from one another. Similarly, the section and the profile of the digging elements 24 can vary as desired.

In addition, it is understood that the device according to the invention, which allows the drilling of a groove at the bottom of a hole, can also be arranged to allow drilling the hole itself. It suffices to provide at the lower end of the tool 3, a suitable drilling tool so that the hole is drilled first and then, preferably stopping the descent of the tool, the digging is then carried out. throat through the expansion of the elements 24 from the retracted position to the emerging position.

Furthermore, the digging elements 24 may not be diamond-coated, in particular when they have to work in a soft rock (chalk for example). They can be made up or coated with any suitable abrasive material.

According to another variant, the membrane or sheath 17 can be arranged around a rigid tube; the channel 22 is then placed in communication with a chamber 21, of annular shape, which is between the membrane 17 and the tube in question.

According to yet another variant, the channel 22 comprises two branches, one for supplying the liquid capable of swelling the membrane 17 (as described above) and the other for bringing into the region of the slots 8 a liquid used for cooling the digging elements 24. In the case of the previous variant where the membrane 17 is arranged around a rigid tube, the second branch of the channel 22 opens out at the bottom of such a tube so that the coolant can rise up the along the digging tools 24.

It goes without saying that the pressure supply system has only been shown diagrammatically at the top of FIG. 1. Thus it is possible to provide a stop valve at the bottom of the vertical cylindrical chamber 26, c 'that is to say at the start of the pipe 27, to avoid the phenomena of expansion by hydrostatic pressure which have been reported above. In addition, it is necessary to provide a pressure reducer or a pressure limiter for the air acting on the water, which makes it possible to choose the ideal cutting pressure on the digging elements 25 according to the nature of these elements. 24 and that of the material to be grooved. Anyway, the aforesaid supply system is arranged so as to bring the liquid down towards the tool 1 first with pressure increase until the elements 24 come into contact with the wall 5, then with maintenance of the optimum cutting pressure until the end of work, then allowing the said liquid to rise until the digging elements are released 24.

Claims (9)

1. A drilling device of the type which comprises a tool (3) adapted to be introduced into a hole and to be extracted therefrom and which comprises drilling elements (24) adapted to be displaced between a retracted position inside the cylindrical surface of the tool (3) and an emergent position in which the rotation of the tool (3) causes the drilling of a groove in the wall of the hole by said elements (24), said tool (3) comprising an impervious coaxial diaphragm (17) which is expansible radially and on which the drilling elements (24) are disposed and the expansion of which causes said elements to pass from the retracted position to the emergent position and vice versa, characterised in that the interior (21) of the diaphragm (17) is closed, in operation, excluding its communication with a conduit (22, 2, 25) connecting the interior (21) of said diaphragm (17) to a source (26) of liquid pressurized by means (29).

2. A device as claimed in Claim 1, characterised in that said drilling elements (24) are mounted on metallic sectors (23), the internal walls of which are in contact with the external wall of the diaphragm (17).

3. A device as claimed in either of the Claims 1 or 2, characterised in that the body of the tool (3) provides radial guide means for the displacement of the drilling elements (24).

4. A device as claimed in any one of the Claims 1 to 3, characterised in that said diaphragm (17) is in the form of a cylindrical sleeve, the two ends of which are appropriately crimped or gripped between the body of the tool (3) and crimping or gripping members (14, 18), one of said members (14) being provided with a passage (22) for the passage of the liquid between a liquid feed conduit (2) and the interior of the diaphragm.

5. A device as claimed in Claim 4, characterised in that said members (14,18) have frustoconical surfaces cooperating with corresponding frustoconical surfaces of the tool to clamp the ends of the sleeve (17).

6. A device as claimed in any one of the Claims 1 to 5, characterised in that the body of the tool (3) has longitudinal extensions separated by slots (8), the diaphragm (17) being disposed under said extensions and the drilling elements (24) being displaced through said slots (8). 7. A device as claimed in Claim 6, characterised in that said extensions (7) have a free end (10) which is fixed to an end member (11) forming one end of the tool.

8. A device as claimed in any one of the Claims 1 to 7, characterised in that it comprises, far away from the tool, a chamber of liquid (26) adapted to be pressurized and means for determining the variation in the volume of liquid in the chamber during the radial expansion of the diaphragm (17).

9. A device as claimed in Claim 8, characterised in that it comprises a manometer (34) or a pressure gauge enabling the pressure of the liquid to be measured during the operation of the device.

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