WO2009007502A1

WO2009007502A1 - Method and apparatus for drilling hole into bedrock

Info

Publication number: WO2009007502A1
Application number: PCT/FI2008/050410
Authority: WO
Inventors: Risto Valkeinen
Original assignee: Sandvik Mining And Construction Oy
Priority date: 2007-07-06
Filing date: 2008-07-04
Publication date: 2009-01-15
Also published as: EP2176492B1; FI20075523L; CN101688432B; KR20100042634A; EP2176492A1; CN101688432A; EP2176492A4; FI20075523A0

Abstract

The invention relates to a method for drilling a hole in a rock with a rock drilling apparatus and to a rock drilling apparatus including a feed beam (1), a rock drill (2) moving along the feed beam (1 ) in the longitudinal direction thereof, a drill rod (3) connected to be rotated by the rock drill (2), a drill bit at the end of the drill rod (3) and a front support (6) locating at the rock-side end of the feed beam (1) and intended for being pushed against the rock during drilling. In the method, at the beginning of the drilling as the drill bit (4) moves in the transverse direction of the feed beam (1) such that the drill rod bends, the feed beam (1) is shifted in relation to the front support (6) in the transverse direction of the feed beam (1). The apparatus includes a transverse shifting device (7) between the front support (6) and the feed beam (1 ), by which the front support (6) and the feed beam (1) may be shifted in relation to one another.

Description

METHOD AND APPARATUS FOR DRILLING HOLE IN BEDROCK

BACKGROUND OF THE INVENTION

[0001] The invention relates to a method for drilling a hole in a rock with a rock drilling apparatus including a feed beam, a rock drill moving along the feed beam in the longitudinal direction thereof, a drill rod connected to be rotated by the rock drill, a drill bit at the end of the drill rod and a front support locating at the rock-side end of the feed beam and intended for being pushed against the rock during drilling, in which method the feed beam of the rock drill is supported during drilling to the rock by pushing the front support of the feed beam against it, whereafter the hole will be drilled.

[0002] The invention further relates to an apparatus for drilling a hole in a rock, the apparatus including a feed beam, a rock drill moving along the feed beam in the longitudinal direction thereof, a drill rod connected to be rotated by the rock drill, a drill bit at the end of the drill rod and a front support locating at the rock-side end of the feed beam and intended for being pushed against the rock during drilling.

[0003] When drilling of a new hole is started on a rock surface, it is fairly common that the drill bit moves laterally to the rock surface. This ensues that, in practice, the hole will be offset from the point intended in the positioning of the rock drilling rig. The reason is that the rock surface is generally inclined or uneven in various ways, and consequently the feed force of the drilling machine, on one hand, and the rotation of the drill bit, on the other hand, generate a force that tends to shift the drill bit laterally. This, in turn, has a consequence that when drilling continues, the drill rod is not in the originally designed drilling direction, but at an angle thereto. Moreover, when the location of the drill bit deviates laterally from the originally designed drilling location, the hole will not be in the designed location. Bending of the drill rod, in turn, strains the drill bit and the drill rod as well as the whole drilling rig, which causes unnecessary wear and shortens the service life of the apparatus.

[0004] From US Patent 4,979,575 is known a solution, in which after preliminary drilling the joints between the boom and the feed beam, and optionally the feed beam in its longitudinal direction are released to move freely in order that the boom and the feed beam may take a substantially strainless position the drill bit still being in the preliminary hole. In this solution the angles between various components and their mutual positions are measured as they rest strainlessly, and after that new directions and positions will be computed in order that the hole would be in a desired location. This is, however, a relatively complicated and time-consuming manner to solve the problem.

BRIEF DESCRIPTION OF THE INVENTION

[0005] The object of the present invention is to provide a method and an apparatus, which allow drilling to be continued, despite a minor lateral shift, in an easy and simple manner without having to redirect the feed beam.

[0006] The method of the invention is characterized in that as the drill bit moves at the beginning of drilling in the transverse direction of the feed beam such that the drill rod bends, the feed beam is shifted in relation to the front support in the transverse direction of the feed beam to the moving direction of the drill bit such that the drill rod becomes substantially straight again. The apparatus of the invention is characterized in that the apparatus includes a transverse shifting device between the front support and the feed beam, by which device the front support and the feed beam may be shifted in relation to one another at least in one direction in the transverse direction of the feed beam.

[0007] The basic idea of the invention is that the drilling support at the front end of the feed beam in the rock drilling rig is connected to the feed beam with a transverse shifting device, wherewith the drilling support may be moved from its normal position in two mutually substantially perpendicular directions transverse to the longitudinal axis of the feed beam, whereby, when preliminary drilling is offset to some extent in the lateral direction from the originally designed location, the feed beam may be shifted in the above- mentioned directions according to the deflection in the direction of the bend such that the feed beam together with the drill rod will be able to rest substantially without strains while substantially maintaining their coaxial direction with the drill bit. Thereafter the drilling support and the feed beam may be locked into place and drilling may continue in the direction of the original hole.

[0008] The invention has an advantage that the hole drilling direction will remain as originally designed just by a simple displacement in the position of the feed beam with respect to the front support. The invention has a further advantage that the solution is simple and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In the following the invention will be described in greater detail in connection with the attached drawings, in which

Figure 1 is a schematic view of a feed beam,

Figures 2a and 2b are schematic views of a shifting device element applicable to the implementation of the invention in the longitudinal and transverse directions of the feed beam, respectively,

Figure 3 is a perspective view of an embodiment of the shifting device,

Figures 4a to 4c show schematically the operation of the invention relative to one shifting direction and

Figure 5 shows schematically a simple solution for measuring the amount of a necessary shift.

DETAILED DESCIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0010] Figure 1 shows schematically a feed beam provided with a transverse shifting device of the invention. It shows a feed beam 1 , on top of which there is a rock drilling machine 2 moving in the longitudinal direction thereof. The feed beam as such and the rock drill and the feeding equipment used for feeding the rock drilling machine are generally well known per se and obvious to a person skilled in the art, and therefore they need not be explained in greater detail. Further, it shows a drill rod 3, at the end of which there is a drill bit 4. At the end of the drilling beam 1 , on the side of the drill bit 4, there is also a front guide 5, wherewith the drill rod is supported during drilling.

[0011] At the front end of the drilling beam 1 there is also a front support 6 that is intended for being pushed against the rock to be drilled and that quite often is a so-called ground peg. The front support 6 is connected to the feed beam 1 with a transverse shifting device 7 whose structure and function will be described later in the text. The feed beam 1 is typically connected to a boom, which is shown in part and which is typically mounted on a drilling base well known per se, not shown. The interconnection of the boom and the feed beam, with the relating actuators, is generally known to a person skilled in the art, and therefore they need not be explained in greater detail.

[0012] Figure 2a shows schematically, seen in the longitudinal direction of the feed beam, one shifting element 7a of the transverse shifting device 7 applicable to the implementation of the invention for mutually shifting the feed beam and the front support in one direction. Figure 2b, in turn, shows the shifting element cut along the line B - B in Figure 2a.

[0013] The shifting element 7a comprises a body consisting of body parts 9a and 9b, which are interconnected with bolts 9c to provide an integral body. A support piece 10 is movably mounted on the body in the transverse direction of the feed beam 1. Between the support piece 10 and the body there is a shifting cylinder 11 , whereby the support piece 10 may be shifted in relation to the body. In the normal position of the shifting element 7a the support piece 10 is advantageously in a position to the body, where it may be shifted substantially the same distance in either direction in its movement direction.

[0014] The body of the shifting element 7a comprises triangular guide grooves whose sliding surfaces are denoted by reference numeral 12. Correspondingly, the support piece 10 comprises edges at an angle that correspond to the grooves in the body and whose sliding surfaces are denoted by reference numeral 13. In this manner the support piece 10 holds in place guided by the grooves in the body, but is able to move in the reciprocating manner in the direction of the arrow shown in Figure 2a by the action of the shifting cylinder 11.

[0015] The structure of a second shifting element 7b is substantially the same as that of the shifting element 7a. The shifting elements 7a and 7b are interconnected successively in the longitudinal direction of the feed beam such that the movement directions of their support pieces are substantially perpendicular to one another and to the longitudinal direction of the feed beam.

[0016] The shifting elements 7a and 7b may be interconnected by connecting their bodies to one another such that their movement directions are transverse to one another. In that case the support pieces, which may move in relation to the bodies and to one another, are connected to the feed beam 1 , and to the front guide 6, respectively. Correspondingly, if the support pieces are interconnected, the bodies that may move in relation to the support pieces and to one another, are connected to the feed beam 1 and to the front guide 6, respectively.

[0017] Figure 3 shows schematically in perspective, how the shifting elements 7a and 7b are interconnected. As it appears from the figure, the bodies of the shifting elements 7a and 7b are at a 90-degree angle to one another and consequently the movement directions of the support pieces 10 are mutually perpendicular.

[0018] Figures 4a to 4c show schematically the operation of the invention relative to one shifting direction. This illustrates, how the invention will be applied when the drill bit is bent only vertically at the beginning of the hole drilling. The front support 6 of the feed beam 1 is supported to the rock 14 and the drilling of the hole is initiated. This is shown in Figure 4a. The figures also show schematically a measuring device 15, which may be utilized in determining the bend of the drill rod. The measuring device is shown in greater detail in Figure 5.

[0019] Figure 4b shows a situation, where, after the drilling has started, the drill bit has shifted downwardly from the starting point, whereby the drill rod 3 has bent. This is illustrated by a broken line 16, which depicts the direction in which the drill rod should run if there were no bending.

[0020] Figure 4c shows a situation, where the feed beam is shifted downwardly in relation to the front support 6, in order that the drill rod 3 could be set as straight as possible for the duration of the drilling and the drilling could be carried out without stressing unnecessarily the drill rod, the drill bit and other drilling equipment. To this effect, the support piece of the shifting member 7b has been shifted upwardly in relation to its body, whereby the body and the feed beam 1 connected thereto have shifted downwardly in relation to the shifting member 7a and the front support 6 such that the drill rod is straight again. If a bend had occurred also in the transverse direction, the support piece of the shifting member 7a would be shifted laterally in an appropriate direction in the corresponding manner so as to straighten out the bend.

[0021] The invention may be implemented with a simple apparatus without any sensors, but the drill operator performs the transverse shifts in a desired manner manually on the basis of a visual perception. However, the invention may be applied by using a separate detector device, which detects a bend of the drill rod in relation to the feed beam, whereby it is more reliable to perform transverse shifts either automatically or by means of a display in front of the drill operator.

[0022] Figure 5 shows schematically a detector device of this kind, which is mounted immovably on the front guide such that in a normal situation the drill rod goes through the detector device. The detector device 15 comprises a body 17 and in the middle thereof, an annular detector 18 surrounding the drill rod 3 and connected to the body 17 of the detector device 15 in the transverse direction thereof to be movable both in vertical and horizontal directions supported by support springs 19. It also comprises sensors 20 that sense if the detector 18 is displaced from its normal position in the direction of both axes. In that case the deflection may be transmitted electrically, for instance, to the display in front of the drill operator, and consequently the drill operator may shift the feed beam in accordance with the display information in the vertical and horizontal directions as desired, until the detector device indicates that the drill rod is straight. Correspondingly, a shift in the horizontal direction to get the feed beam in a correct position is performed in the corresponding manner.

[0023] In the above, in the specification and the drawings describe the invention by way of example only, and the scope of protection is defined in the claims. The shifting device may be assembled in the above-described manner of separate shifting members that are connected to one another and between the feed beam and the front support. The shifting device may also be implemented as a compact whole such that the same body comprises the support pieces and the transfer cylinders of both directions. The body may also be made of a mainly integral part, in which the guide grooves and other necessary elements are machined. Other implementations are also possible within the general knowledge of a person skilled in the art. The guides between the support pieces and the bodies may be different from what is presented above to meet a particular need. Likewise, the position and the mounting of the shifting cylinder may be different. The shape of the support pieces may also vary.

[0024] It is essential that the feed beam comprises, between the front support and the feed beam, a shifting device, by which the position of the feed beam and the front support may be shifted in relation to one another in the direction of two axes that are advantageously mutually perpendicular and transverse to the longitudinal direction of the feed beam, so that after initial drilling the drill rod will be set substantially straight for actual drilling.

Claims

1. A method for drilling a hole in a rock with a rock drilling apparatus including a feed beam (1), a rock drill (2) moving along the feed beam (1) in the longitudinal direction thereof, a drill rod (3) connected to be rotated by the rock drill (2), a drill bit at the end of the drill rod (3) and a front support (6) locating at the rock-side end of the feed beam (1) and intended for being pushed against the rock (16) during drilling, in which method the feed beam (1) of the rock drill (2) is supported during drilling to the rock (16) by pushing the front support (6) of the feed beam (1) against it, whereafter the hole will be drilled, characterized in that as the drill bit (4) moves at the beginning of the drilling in the transverse direction of the feed beam (1) such that the drill rod (3) bends, the feed beam (1) is shifted in relation to the front support (6) in the transverse direction of the feed beam (1) to the moving direction of the drill bit (4) such that the drill rod (3) becomes substantially straight again.

2. The method of claim ^ characterized in that the bend in the drill rod (4) is measured and the feed beam (1) is shifted in relation to the front support (6) on the basis of the measured bend.

3. An apparatus for drilling a hole in a rock, the apparatus including a feed beam (1), a rock drill (2) moving along the feed beam (1) in the longitudinal direction thereof, a drill rod (3) connected to be rotated by the rock drill (2), a drill bit at the end of the drill rod (3) and a front support (6) locating at the rock-side end of the feed beam (1) and intended for being pushed against the rock (16) during drilling, characterized in that the apparatus comprises between the front support (6) and the feed beam (1) a transverse shifting device (7), by which the front support (6) and the feed beam (1) may be shifted in relation to one another at least in one direction in the transversely to the feed beam (1).

4. The apparatus of claim 3, characterized in that the transverse shifting device (7) is arranged to shift the front support (6) and the feed beam (1) in two mutually transverse directions transversely to the feed beam

(D-

5. The apparatus of claim 3 or 4, characterized in that the transverse shifting device (7) comprises a body and with respect to the body two support pieces (10) moving in mutually transverse directions and, for both support pieces (10), a pressure medium cylinder acting between the body and the support piece (10) for moving the support piece (10) in relation to the body.

6. The apparatus of any one of claims 3 to 5, characterized in that the transverse shifting device (7) consists of two shifting members (7a, 7b), both of which comprise a body (9a, 9b), a support piece (10) moving in relation to the body (9a, 9b) and a pressure medium cylinder acting between the body (9a, 9b) and the support piece (10) for moving the support piece (10) and the body (9a, 9b) in relation to one another, and that the shifting members (7a, 7b) are interconnected either by connecting the support pieces (10) to one another or the bodies (9a, 9b) to one another such that the bodies (9a, 9b) or correspondingly the support pieces (10) are able to move in relation to the interconnected parts in a movement direction transverse to one another.

7. The apparatus of any one of claims 3 to 6, characterized in that it comprises a detector device (15) having sensors (20) for sensing a bend in the drill rod (3) in the vertical and horizontal directions of the feed beam (1).

8. The detector device of claim 7, characterized in that it comprises a body (17) having an opening and in the opening of the body (17) an annular detector (18), through which the drill rod (3) passes, that the annular detector (18) is connected to the body (17) by means of springs (19) that are transverse to one another such that it may move in relation to the body (17) and that the sensors (20) are mounted to measure the displacement of the detector (18) from its normal position.