Device for guiding the rotation of a drilling tool and associated method

Abstract

A guidance device (10) for the rotation of a drilling tool (12), the device (10) comprising a tubular longitudinal element (34), a drive shaft (20) passing longitudinally through the tubular element (34), the shaft (20) being rotatably mounted in the tubular element (34) to drive the drilling tool (12) in rotation, the guidance device (10) comprising bearings (38) mounted between the tubular element (34) and the shaft (20), each bearing (38) being fixed on at least one mounting region (30) on the shaft (20), characterized in that the bearing (38) comprises at least one spherical roller bearing with a tapered bore (40) and in which, at least in the mounting region (30), the shaft (20) has a taper less than or equal to 1:12 and / or connecting radii greater than 1 / 12th of the outside diameter of the shaft (20).

Description

[0001] The present invention relates to a device for guiding the rotation of a drilling tool, comprising a tubular longitudinal element, a transmission shaft passing longitudinally through the tubular element, the shaft being rotatably mounted in the tubular element to drive the drilling tool in rotation and transmit axial forces to it, the guiding device comprising bearings mounted between the tubular element and the shaft, each bearing being fixed to at least one fixing region on the shaft.

[0002] Such a device is intended for use in drilling in the fields of the oil industry, civil engineering, geothermal energy and more generally in all areas of underground trenchless intervention.

[0003] Such a device is used in all types of drilling, from fully mechanical drilling to drilling incorporating electronic equipment.

[0004] Such a device is intended to form, for example, a non-rotating stabilizer included in a drill string or to be used in a downhole motor with an elbow connection, or in a directional drilling tool.

[0005] Such a device is, for example, configured to guide a drilling tool in rotation and transmit to it the entire force of a drill string. This corresponds to a power transmission through the device. The drill string is controlled by a drive system located on the surface of the excavation.

[0006] WO9964712A1 or FR 2 898 935 discloses a device of the aforementioned type comprising a shaft passing longitudinally through a tubular longitudinal element, the shaft being rotatably mounted in the tubular element. The device comprises a bearing mounted between the tubular element and the shaft, the bearing being fixed on at least one fixing region on the shaft. The bearing forms a pivot, sliding pivot, annular linear or ball joint type connection between the shaft and the element. The bearing is axially locked on the shaft by a shoulder or a groove.

[0007] However, such a device can still be improved. A shaft with such a shoulder has lower fatigue resistance compared to a smooth shaft, particularly in rotary bending due to stress concentrations.

[0008] Furthermore, the cost and manufacturing time of such a shaft can be high, because the manufacture of a shaft with shoulders involves the implementation of a preform before machining the shaft and / or significant material removal by turning a large diameter. These operations are expensive in terms of raw material and machining. The stress concentration coefficients are also increased at discontinuities in the shaft section.

[0009] Furthermore, maintenance can generally only be done from one side, involving the complete disassembly of the device regardless of the extent of the repair.

[0010] An aim of the invention is therefore to obtain a device for guiding the rotation of a drilling tool which has an increased service life, while limiting manufacturing and maintenance costs.

[0011] To this end, the invention relates to a device of the aforementioned type, characterized in that the bearing comprises at least one spherical roller bearing with a tapered bore to form a pivot, sliding pivot, ball joint or annular linear type connection between the tubular element and the shaft, and in which, at least in the fixing region, the shaft has a taper less than or equal to 1:12 and / or connection radii greater than 1 / 12th of the outside diameter of the shaft.

[0012] The guidance device according to the invention may comprise one or more of the following characteristics, taken individually or in any technically possible combination: the shaft comprises a central body and ends projecting axially relative to the central body, the shaft having a diameter variation of less than 5% over the entire central body and advantageously the ends; the shaft comprises at least one annular or helical groove and the bearing comprises at least one split conical ring received on the groove having a bore of complementary shape to the groove and a conical outer surface on which the stop is mounted; the bearing comprises a spacer applied to the fixing zone arranged between the stop and the bearing; the bearing comprises a withdrawal sleeve applied to the fixing region, the withdrawal sleeve having a threaded collar, the spherical roller bearing with a conical bore being secured to the shaft by means of the withdrawal sleeve;the bearing comprises a rotary sealing device comprising an inner part secured to the shaft, the inner part being screwed onto the threaded collar of the dismantling sleeve; the device comprises a removable clamping ring for an element driven in rotation by the shaft or driving the shaft in rotation, at least at one of the ends of the shaft, the bearing comprising a rotary sealing device comprising an inner part secured to the shaft, the bearing being equipped with a shim spacer cancelling the play between the inner part of the rotary sealing device and the removable clamping ring;the shaft is flexible, the tubular element comprising a main body and a housing which can be oriented relative to the main body by bending the shaft, at least one first bearing being arranged between the main body and the shaft, at least one second bearing being arranged between the orientable housing and the shaft, the guide device comprising at least one central bearing comprising an additional bearing ensuring at least one annular linear type connection between the main body and the shaft; the tubular element is rigid in bending.;

[0013] The invention also relates to a method for replacing a bearing of a guide device, the method comprising the following steps: possible disassembly of a rotary sealing device; separation of the bearing from the shaft by possible extraction of a disassembly sleeve from the bearing; movement of the bearing to one end of the shaft by sliding on the shaft without disassembly of the shaft from the tubular element; reassembly of the bearing or a replacement bearing without disassembly of the shaft from the tubular element; separation of the bearing from the shaft possibly by replacing the disassembly sleeve; possible reassembly of the rotary sealing device.

[0014] The invention will be better understood by reading the following description, given solely by way of example and with reference to the appended drawings in which: there Figure 1 is a schematic view in partial section along a median plane of a first device according to the invention arranged for example in a non-rotating stabilizer; the Figure 2 is a partially cutaway perspective view along a median plane of one end of the shaft of the device of the figure 1 equipped with a bearing; and the Figure 3 is a schematic view in partial section along a median plane of a second device according to the invention arranged for example in a directional drilling tool.

[0015] A rotational guidance device 10 according to the invention is used in a well drilling installation.

[0016] The drilling installation comprises a surface installation (not shown). The surface installation rotates and transmits axial forces to a drilling tool 12 by means of a drill string 14, through the guide device 10.

[0017] In all that follows, the terms “upstream” and “downstream” refer to the normal direction of drilling progress.

[0018] The surface installation comprises means for supporting, rotating and transmitting axial forces of the drilling tool 12 and means for circulating a drilling liquid.

[0019] The drill string 14 is rotated by the surface installation. It is formed of a plurality of cylindrical tubes (not shown) transmitting torque and axial forces to the guide device 10. The cylindrical tubes are oriented along a main axis ZZ of the well.

[0020] A first example of a guidance device 10 according to the invention is shown in the figure 1 . Advantageously, in the example of the figure 1 , the device 10 forms a non-rotating stabilizer.

[0021] The guide device 10 comprises a shaft 20 rotated by the drill string 14, a tubular element 34 supporting the rotating shaft 20 and bearings 38 guiding the rotation of the shaft 20 in the tubular element 34 in contact with the wall of the well being drilled.

[0022] The shaft 20 has a central passage 22 and a substantially cylindrical outer surface. The shaft 20 is located in the extension of the drill string 14 and is oriented along the main axis ZZ of the well.

[0023] In this first example, the shaft 20 is rigid and has a high flexural modulus making the guide device 10 not very flexible perpendicular to the ZZ axis. By “rigid”, it is meant that the shaft 20 has a maximum angle of deformation in bending between two bearings of less than 0.1°. In a variant which will be described below, the shaft 20 is flexible and has a minimum angle of deformation in bending between two bearings, greater than 0.2°.

[0024] The shaft 20 comprises a central body 26 having a smooth outer surface and ends 28 projecting axially relative to the central body 26. The ends 28 of the shaft 20 are connected on the one hand to the drill string 14 by an upstream threaded connection 14A and on the other hand to the drilling tool 12 by a downstream threaded connection 12A. The upstream threaded connection 14A and the downstream threaded connection 12A are in particular provided with conical threads and here have a frustoconical shape.

[0025] The shaft 20 comprises fixing regions 30 of the bearings 38 on its outer surface. The fixing regions 30 are in particular located on the central body 26, adjacent to the ends 28 of the shaft 20.

[0026] At least in each attachment region 30, preferably over the entire length of the shaft except for the ends 28, the outer surface of the shaft 20 is substantially cylindrical.

[0027] The shaft 20 has diameter variations of less than 5% between the smallest diameter of the shaft 20 in the fixing region 30 and the largest diameter of the shaft 20 in the same fixing region 30 and advantageously over the entire length of the shaft with the exception of the ends 28 or including the ends 28.

[0028] In addition, at least in each attachment region 30, preferably over the entire length of the shaft 20 except for the ends 28 or including the ends 28, the shaft 20 has a taper less than or equal to 1:12 and / or connection radii greater than 1 / 12 th of the outer diameter of the shaft in the attachment region 30.

[0029] Advantageously, at least in each fixing region 30, preferably over the entire length of the shaft 20 with the exception of the ends 28 or including the ends 28, in projection in any half-plane passing through the main axis ZZ, the outer surface of the shaft 20 is continuously derivable, the outer surface thus not having any slope discontinuity on the projected curve of the outer surface of the shaft 20.

[0030] A binding region 30 is illustrated in figure 2 The fixing regions 30 constitute the region where the bearings 38 are applied.

[0031] In the attachment region 30, the shaft 20 preferably comprises at least one annular or helical groove 32 formed in the outer surface of the shaft 20.

[0032] In reference to the figure 1 , the tubular element 34 defines a central housing and a cylindrical outer surface advantageously equipped with pads to bear on the wall of the well while allowing the drilling mud to circulate. The tubular element 34 is oriented along the main axis ZZ of the well, in the extension of the drill string 14. The tubular element 34 receives the shaft 20 in the central housing along the same orientation axis ZZ.

[0033] The length along the main axis ZZ of the tubular element 34 coincides with the length of the central body 26 of the shaft 20. In the example of the figure 1 , the tubular element 34 is in one piece over its entire length. Advantageously, at least one end 28 of the shaft 20, advantageously the two ends 28 of the shaft 20 protrude on either side relative to the tubular element 34.

[0034] The central housing of the tubular element 34 opens at its ends through axial openings 36.

[0035] The tubular element 34 delimits at its ends annular cavities for housing the bearings 38 between the shaft 20 and the tubular element 34. The annular cavities axially extend the central housing.

[0036] The tubular element 34 is intended to bear against the wall of the drilled well and to remain fixed or substantially fixed in rotation relative to the wall of the well.

[0037] Each bearing 38 forms a pivot, sliding pivot, ball joint or annular linear type connection between the element 34 and the shaft 20. The shaft 20 is driven in rotation by the drill string 14, the tubular element 34 remaining fixed or substantially fixed in rotation around the axis ZZ relative to the wall of the well being drilled by means of the connection formed by the bearings 38.

[0038] An example of a 38-step step is shown in figure 2 .

[0039] The bearing 38 comprises a spherical roller bearing with a tapered bore 40 providing the aforementioned ball joint or annular linear connection.

[0040] The bearing 38 further comprises a rear stop 42 having a cylindrical outer surface and a tapered bore. It further comprises a split tapered ring 44 for mounting the rear stop 42.

[0041] The stop 42 cooperates with the conical ring 44 so that they form an axial stop. The stop 42 is positioned on the shaft 20 in the fixing region 30 axially opposite the end 28 of the shaft 20.

[0042] The conical ring 44 has a central passage complementary to the profile of at least one circular or helical groove of the shaft and a conical outer surface.

[0043] The conical ring 44 is fixedly mounted on the shaft 20 at the annular or helical groove 32. The conical surface of the conical ring 44 is inserted in a complementary manner into the conical bore of the stop 42. The conical ring 44 and the stop 42 are thus in axial coincidence along the main axis ZZ, the stop 42 being fixed in translation along the shaft 20.

[0044] The bearing 38 also comprises a spacer 46 arranged in contact with the stop 42 along the main axis ZZ. The spacer 46 is here a ring connecting the stop 42 with the inner ring of the bearing 40.

[0045] The bearing 40 is a spherical roller bearing with a tapered bore having a cylindrical outer surface and a tapered inner bore. The bearing 40 comprises an inner ring, intended to be driven in rotation together with the shaft 20, an outer ring intended to be fixed in rotation in the housing of the tubular element 34 and barrel-shaped rollers interposed between the inner ring and the outer ring.

[0046] The bearing 38 comprises a dismounting sleeve 48 with a cylindrical inner surface resting on the shaft 20 on which the bearing 40 is mounted. The dismounting sleeve 48 is driven in rotation by the shaft 20. The dismounting sleeve 48 associated with the stop 42 allows the temporary embedding of the inner ring of the bearing 40 relative to the shaft 20.

[0047] The withdrawal sleeve 48 comprises a support skirt 50 for the bearing 40 and a threaded collar 52. The support skirt 50 comprises a conical outer surface on which the bearing 40 is mounted.

[0048] The disassembly sleeve 48 has a cylindrical inner surface fixedly applied to the cylindrical fixing region 30 by axial thrust along the ZZ axis towards the stop 42 during assembly.

[0049] The threaded collar 52 has a threaded cylindrical outer surface. It is here made in one piece with the bearing support skirt 50. The threaded collar 52 is located closer to the end 28 of the shaft 20 than the support skirt 50.

[0050] The bearing 38 further comprises a rotary sealing device 54. The rotary sealing device 54 comprises an inner portion 56 fixed relative to the shaft 20 and an outer portion 58 fixed relative to the tubular element 34, the outer portion 58 being concentric and mounted around the inner portion 56.

[0051] The inner part 56 is advantageously screwed onto the collar 52 of the disassembly sleeve 48.

[0052] The inner part 56 comprises a threaded crown 60 complementary to the thread of the collar 52 of the disassembly sleeve 48.

[0053] The threaded crown 60 is suitable for being screwed onto the thread of the threaded collar 52 of the disassembly sleeve 48. The inner part 56 is thus driven in rotation around the axis ZZ.

[0054] The sealing device 54 further comprises an inner annular seal 62. The inner annular seal 62 is interposed in a sealed manner between the shaft 20 and the inner part 56 around the axis ZZ. The inner annular seal 62 is suitable for being driven in rotation by the shaft 20. The inner part 56 being screwed onto the dismantling sleeve 48, a rotary assembly 64 comprising the inner annular seal 62, the inner part 56, the dismantling sleeve 48, the inner ring of the bearing 40, the stop 42, the conical ring 44 and the spacer 46 is driven integrally in rotation around the axis ZZ by the shaft 20.

[0055] The sealing device 54 comprises an outer annular rotary seal 66. The outer annular seal 66 is placed between the inner part 56 and the outer part 58. The outer annular seal 66 is suitable for allowing rotation of the inner part 56 relative to the outer part 58. The rotary annular seal 66 has a single or double lip or is a KALSI seal.

[0056] The sealing device 54 further comprises an external annular seal 63. The external annular seal 63 is placed between the external part 58 and the tubular element 34. The annular seal 63 is capable of ensuring sealing between the external part 58 and the tubular element 34.

[0057] The bearing 38 also includes a front shim spacer 68 mounted on the shaft 20. The shim spacer 68 is pressed against the inner part 56 of the sealing device 54 along the main axis ZZ and at the threaded connection 12A or 14A of the figure 1 .

[0058] The shim spacer 68 is the part of the bearing 38 closest to the end 28 of the shaft 20 associated with the bearing 38.

[0059] Thanks to the structure which has just been described, the bearings 40 of each bearing 38 can easily be made temporarily integral with the shaft 20 and removed from the latter to be replaced.

[0060] A method of replacing bearings 40 of the guide device 10 will now be described. This method is implemented for bearings 40 in a bearing 38 adjacent to one end 28 of the shaft 20 or for a bearing 38 in contact with a smooth shaft 20 up to one of its ends 28.

[0061] In a first phase, the shim spacer 68 is removed from the sealing device 54.

[0062] Then, the sealing device 54 is dismantled by unscrewing the threaded crown 60 relative to the threaded collar 52 and extracting the outer part 58 of the sealing device 54 from the tubular element 34. The bearing 40 is then directly accessible.

[0063] The dismantling sleeve 48 is extracted by sliding it along the shaft 20 towards the end 28 using a hydraulic extraction tool screwed onto the collar 52 of the dismantling sleeve 48 and bearing on the inner ring of the bearing 40. Then, the bearing 40 is removed.

[0064] Then, a new bearing 40 is reintroduced until it stops against the ring 46. The dismantling sleeve is then pushed axially while bearing on the end 28 of the shaft 20. Finally, the sealing device 54 is mounted, followed by the shim spacer 68.

[0065] The replacement method does not require disassembly of the shaft 20 from the tubular element 34.

[0066] The substantially smooth outer surface of the shaft 20 according to the invention allows easy assembly and disassembly of the bearings 40, the bearings 40 being able to slide along the shaft 20.

[0067] In another embodiment not shown, the shaft 20 has a region 30 having a tapered surface on which the tapered bore of the spherical roller bearing 40 is directly mounted. The tapered region of the shaft 20 axially and radially fixes the bearing 40 relative to the shaft 20 without the use of a withdrawal sleeve 48.

[0068] The sealing device 54 is then adjacent to the bearing 40 without the presence of the threaded collar 52.

[0069] In another embodiment, the conical threads of the ends 28 of the shaft 20 are replaced by cylindrical parts allowing the attachment of shrink-fit connections advantageously with hydraulic control. The bearing 38 advantageously comprises a removable shrink-fit (not shown) as described in FR 2 989 749. The shrink-fit extends between the sealing device 54 and the drilling tool 12 or the drill string 14, around the end 28 of the shaft 20.

[0070] The shim spacer 68 is advantageously present between the sealing device and the hoop, guaranteeing the absence of play between the inner part 56 of the rotary sealing device 54 and the removable tightening hoop.

[0071] The hoop is suitable for temporarily securing an element driven in rotation by the shaft 20 or driving the shaft 20 in rotation.

[0072] The hoop is capable of being activated between a loose configuration and a tightening configuration of the element. It advantageously comprises at least one tightening orifice capable of receiving a fluid for moving the hoop and a plug. The hoop is capable of moving from a loose configuration to its tightening configuration by pumping fluid and possibly by fitting a nut as described in FR 2 989 749.

[0073] In another embodiment, visible on the figure 3 , the guidance device 10 is integrated into a directional drilling tool, as described in FR 2 898 935.

[0074] Unlike Device 10 of the figure 1 , the tubular element 34 comprises a main body 70 and a housing 72 which can be oriented relative to the main body 70 between a straight position visible on the figure 3 and a plurality of inclined positions relative to the main body 70.

[0075] The main body 70 is positioned upstream of the orientable housing 72. The tubular element 34 notably comprises at least one connection located between the main body 70 and the orientable housing 72 along the main axis ZZ.

[0076] The shaft 20 is flexible and passes through the main body 70 and the orientable housing 72 along the main axis ZZ. The maximum bending angle of the shaft 20 is, for example, between 0.5° and 1.5° taken between its ends.

[0077] The guide device 10 comprises a first bearing 38A connecting the main body 70 to the shaft 20 and a second bearing 38B connecting the orientable housing 72 to the shaft 20. The two bearings 38A, 38B are located on the fixing regions 30 near the ends 28 of the shaft 20.

[0078] The guide device 10 also comprises a central bearing 38C between the main body 70 and the shaft 20. The central bearing 38C provides an annular linear type connection between the main body 70 and the shaft 20. The central bearing 38C is arranged near the end of the main body 70 located on the side of the orientable housing 72.

[0079] The central bearing 38C comprises a spherical roller bearing 40 with a tapered bore and a locking ring. The shaft 20 has a tapered bearing surface in this fixing region 30. The bearing 40 is axially locked using the locking ring screwed or pinned onto the shaft 20.

[0080] The use of tapered bore spherical roller bearings 40 makes the rotary connection between the shaft 20 and each of the main body 70 and the steerable housing 72 reliable, even when the shaft 20 is bent and the steerable housing tilts, for example, to perform directional drilling.

[0081] In an embodiment visible on the figures 1 And 3 , the 38B bearing comprises several 40 spherical roller bearings with tapered bores.

[0082] More generally, the device according to the invention 10 comprises a substantially smooth shaft 20, therefore very resistant to fatigue, in particular in rotary bending. Indeed, stress concentrations on the surface of the shaft 20 are avoided since the shaft is devoid of shoulders.

[0083] The calculated lifetime of such a shaft 20 in rotary bending is thus greatly extended, even infinite at 90% reliability, while allowing optimal directional capacity of the system.

[0084] The presence of a substantially smooth outer surface simplifies the machining of the shaft 20 and thus reduces costs and production time.

[0085] The exclusive use of spherical roller bearings 40 with tapered bore makes it possible to obtain robust performance, thanks to their self-aligning capacity, no bending deformation altering the operation of the bearing 40. In addition, no play is possible between the inner rings of the bearings 40 secured to the shaft 20 and the shaft 20.

[0086] In addition, the linear contacts between rollers and rings as well as the large number of rollers allow the 40 bearings to withstand high loads, including in the presence of vibrations as well as good shock resistance.

[0087] 40 bearings with tapered bores are attractive because they are standard and available worldwide, ensuring easy, fast and economical maintenance.

[0088] Additionally, 40 tapered bore spherical roller bearings are typically stabilized at 200°C, ensuring improved reliability during drilling.

[0089] The removable hoop as described in FR 2 989 749 allows the axial locking of the bearing 38 while ensuring the connection between the shaft 20 and the rod string 14 and / or the drilling tool 12.

[0090] The spacer 46 and the shim spacer 68 allow simple adjustments of the position of the parts of the bearings 38 along the main axis ZZ while avoiding precise machining of the parts of the bearing 38, the tubular element 34, and the shaft 20. This also reduces manufacturing and maintenance costs.

[0091] The sealing device 54 associated with the static sealing joints 62 and 63 allow the pressurization of the device 10.

[0092] The replacement of the bearings 40 and the maintenance of the device 10 are therefore simple and easy. The replacement of the bearings 40 can be carried out close to the drilling site and allows for rapid and economical maintenance. In addition, the substantially smooth shaft 20 allows access to both sides of the shaft 20 and the device 10 for maintenance, the tubular element 34 does not need to be disassembled for the replacement of the parts of the bearing 38 located at the ends of the shaft 20.

[0093] In a preferred embodiment, the shaft is rotatably mounted in the tubular element.

[0094] In view of the above, it should be noted that since the shaft is a through shaft, the bearings are not subjected to the axial force transmitted by the drill string 14 to the drilling tool 12 via the shaft 20.

[0095] Likewise, the buckling limit of the shaft 20, due to the drilling forces, is advantageously greater than the maximum axial force transmitted by the drill string 14 to the shaft 20.

[0096] It follows from the above that the maximum bending angle of the shaft 20, for example between 0.5° and 1.5°, is taken between the tangents of its ends.

[0097] As specified above, the device according to the invention 10 comprises a substantially smooth shaft 20, therefore very resistant to fatigue, in particular in rotary bending, in particular because stress concentrations on the surface of the shaft 20 are avoided since the shaft is devoid of shoulders, collars and / or grooves.

[0098] Furthermore, the presence of a substantially smooth outer surface, in addition to simplifying the machining of the shaft 20 and reducing production times as mentioned previously, also makes it possible to reduce the energy required for the production of the shaft 20.

[0099] As shown on the figure 2 , which represents the fixing region 30, but on which the tubular element 34 is not shown, the bearing 38 comprises for example at least one stop having a cylindrical outer surface and a conical inner bore. Preferably, the bearing 38 is filled with degassed oil and is pressurized to allow the pressurization of the device 10.

[0100] Such a guidance device is thus, for example, intended to be used in a directional drilling tool.

Claims

1. A device (10) for guiding a drilling tool (12) in rotation, the device (10) including a tubular longitudinal element (34), a transmission shaft (20) passing longitudinally through the tubular element (34), the shaft (20) being rotatably mounted in the tubular element (34) in order to rotate the drilling tool (12) and to transmit axial forces thereto, the guiding device (10) comprising bearing blocks (38) mounted between the tubular element (34) and the shaft (20), each bearing block (38) being attached to at least one attachment region (30) on the shaft (20), characterized in that the bearing block (38) includes at least one tapered bore ball-joint roller bearing (40) for forming a pivot linkage, a sliding pivot linkage, an ball joint linkage or a linear annular linkage between the tubular element (34) and the shaft (20), and wherein, at least in the attachment region (30), the shaft (20) has a taper less than or equal to 1:12 and / or bend radii greater than 1 / 12th of the outer diameter of the shaft (20).

2. The guiding device (10) according to claim 1, wherein the shaft includes a central body (26) and ends (28) protruding axially from the central body (26), the shaft (20) having a variation of diameter of less than 5% over the entire central body (26) and advantageously the ends (28).

3. The guiding device (10) according to any of the preceding claims, wherein the bearing block (38) includes at least one abutment (42) having a cylindrical outer surface and a tapered inner bore.

4. The guiding device (10) according to claim 3, wherein the shaft (20) includes at least one annular or helical groove (32) and the bearing block (38) includes at least one split tapered ring (44) received on the groove (32) having a bore with a shape matching the groove (32) and a tapered outer surface on which the abutment (42) is mounted.

5. The guiding device (10) according to claim 3 or 4, wherein the bearing block (38) includes a spacer (46) applied over the attachment region (30) arranged between the abutment (42) and the roller bearing (40).

6. The guiding device (10) according to any of the preceding claims, wherein the bearing block (38) includes a disassembly sleeve (48) applied over the attachment region (30), the disassembly sleeve (48) having a threaded collar (52), the tapered bore ball-joint roller bearing (40) being rigidly attached to the shaft (20) by means of the disassembly sleeve (48).

7. The guiding device (10) according to claim 6, wherein the bearing block (38) includes a rotary sealing device (54) comprising an inner part (56) rigidly attached to the shaft (20), the inner part (56) being screwed onto the threaded flange (52) of the disassembly sleeve (48).

8. The guiding device (10) according to any of the preceding claims, wherein the device (10) includes a removable hoop for clamping an element rotated by the shaft (20) or rotating the shaft (20), at least at one of the ends (28) of the shaft (20), the bearing block (38) including a rotary sealing device (54) comprising an inner part (56) rigidly attached to the shaft (20), the bearing block (38) being equipped with a shimming spacer (68) canceling the play between the inner part (56) of the rotary sealing device (54) and the removable hoop clamp.

9. The guiding device (10) according to any of the preceding claims, wherein the shaft (20) is flexible, the tubular element (34) including a main body (70) and a housing (72) which can be swiveled with respect to the main body (70) by bending the shaft (20), at least one first bearing block (38) being arranged between the main body (70) and the shaft (20), and at least one second bearing block (38) being arranged between the swiveling housing (72) and the shaft (20), the guiding device (10) including at least one central bearing block (38C) including an additional roller bearing (40) ensuring at least one annular linear linkage between the main body (70) and the shaft (20).

10. A method for replacing a roller bearing (40) of a guiding device (10) according to any of the preceding claims, the method comprising the following steps: - disassembling, if need be, a rotary sealing device (54); - separation of the roller bearing (40) from the shaft (20) by extraction, if appropriate, of a disassembly sleeve (48) of the bearing block (38); - moving the roller bearing (40) to one end of the shaft (20) by sliding on the shaft (20) without disassembling the shaft (20) of the tubular element (34); - remounting the roller bearing (40) or a replacement roller bearing (40) without disassembling the shaft (20) of the tubular (34) element; - rigidly attaching the roller bearing (40) to the shaft (20), if appropriate by remounting the disassembly sleeve (48); - remounting, if need be, the rotary sealing device (54).

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