Background of the invention

[0001] The invention relates to a rock drilling machine that comprises a body, a percussion element arranged inside the body and, further, a drill shank, to which a tool may be attached for breaking rock. A percussion device comprises a percussion element that generates stress pulses through the shank to the tool. Further, the rock drilling machine comprises an axial bearing having one or more pressure medium-operated axial pistons, with which the shank may be pushed in the axial direction relative to the body a predefined travelling length toward the stroke direction. The impact surface of the shank may then be set at a required axial point for receiving stress pulses. The axial piston is operated by pressure medium, whereby it comprises a working pressure surface that is located in a working pressure space belonging to the axial bearing, to which the pressure of the pressure medium may be fed from a feed channel. A force may then be directed to the axial piston in the stroke direction. The field of the invention is defined in more detail in the preamble of the independent claim of the patent application.

[0002] It is known to equip a rock drilling machine with an axial bearing, with which a drill shank belonging to the rock drilling machine may be moved to a planned impact point during drilling. The striking power may then be adjusted by adjusting the position of the drill shank. In addition, the axial bearing may be used to damp the stress pulses reflected back to the rock drilling machine from the rock. The axial bearing is typically positioned in an intermediate flange between the front body and back body of the rock drilling machine. A drawback with the known axial bearings is that the supporting forces caused by the operation of the axial bearing cause unnecessary strain on the structures of the rock drilling machine.

Brief description of the invention

[0003] It is an object of the invention to provide a novel and improved rock drilling machine.

[0004] The rock drilling machine of the invention is characterised in that the axial bearing comprises at least one axial bearing module that comprises at least one axial piston, at least one seal, at least one bearing surface, and a module frame; and that the axial bearing comprises a sleeve-like axial bearing support that is arranged to transmit supporting forces caused by the operation of the axial bearing directly from the axial bearing module to the body of the rock drilling machine.

[0005] The idea of the invention is that the axial bearing of the rock drilling machine comprises one or more axial bearing modules that are detachable and installable in place in a space in the body in one piece. The axial bearing module comprises one or more axial pistons, one or more bearing surfaces, seals, and a module frame. The supporting forces caused by the operation of the axial bearing are transmitted from the axial bearing module to the body of the rock drilling machine by means of a separate sleeve-like axial bearing support.

[0006] The invention provides the advantage that the axial bearing module comprises in one uniform entity all essential components necessary for the operation of the axial bearing. Thus, the axial bearing module may conveniently be detached in one entity and replaced by a new one. Further, worn seals and possibly also bearings may be detached and replaced in a repair shop in good conditions. With the axial bearing support, supporting forces may be transmitted to the body at a point where they will not cause undesired strains to the structures. This way, it is possible to avoid, among other things, problems that are caused by the strain and wear directed to the joint surfaces and the loads directed to joint members, such as tie bolts. The structure of the invention may thus be more robust and stronger than the earlier solutions.

[0007] The idea of an embodiment is that the axial bearing is arranged in a space in the body from the direction of the drill shank, that is, front- loaded. The axial bearing support is then arranged to transmit to the body at least the supporting forces acting in the stroke direction.

[0008] The idea of an embodiment is that the axial bearing is arranged in a space in the body from a direction opposite to the drill shank, that is, breech-loaded. The axial bearing support is then arranged to transmit to the body at least the supporting forces acting in the return direction.

[0009] The idea of an embodiment is that the axial bearing module and axial bearing support are arranged in a space in the body axially one after the other. The axial bearing support then transmits supporting forces to the body at least in the direction opposite to the installation direction.

[0010] The idea of an embodiment is that the axial bearing module is arranged entirely or at least partly inside the axial bearing support. [0011] The idea of an embodiment is that the axial bearing module and axial bearing support form a cartridge that is installable in a space in the body and detachable from it in one entity. The handling of such a cartridge is quick and easy.

[0012] The idea of an embodiment is that the axial bearing support is an elongated sleeve-like piece having along its first end a fastening flange with means for transmitting supporting forces to the body.

[0013] The idea of an embodiment is that the axial bearing support comprises a fastening flange arranged against an end surface at the front end or alternatively at the back end of the body. The fastening flange is also connected to the body with one or more fastening bolts. The fastening flange and bolts transmit supporting forces to the body.

[0014] The idea of an embodiment is that the body of the rock drilling machine is formed of two or more inter-connected body parts. However, the joints between the body parts are not at the axial bearing or under the effect of the supporting forces so that no supporting forces caused by the operation of the axial bearing are directed to the joints. A uniform structure along the axial bearing receives the opposite-direction supporting forces and transmits them onward as necessary.

[0015] The idea of an embodiment is that the axial bearing module is detachable and installable in place in one piece in a space located in the body without needing to dismantle the body parts of the rock drilling machine. Because the body of the rock drilling machine need not be dismantled when installing the axial bearing module, minor maintenance, component replacements, and other repairs of the axial bearing may be done on work site and without needing to detach the rock drilling machine from the feed beam.

[0016] The idea of an embodiment is that the body of the rock drilling machine is one single uniform piece with no joint surfaces. A flushing chamber possibly located at the front end of the body and a back cover or pressure accumulator at the back end are not part of the body. A one-piece body does not have joint surfaces and tie bolts between parts thereof, to which loads could be directed by the supporting forces caused by the axial bearing. A one-body rock drilling machine may thus be stronger and more maintenance- free than before. In addition, it may be lighter and shorter.

[0017] The idea of an embodiment is that the supporting forces of the axial bearing are transmitted to the body part so that the supporting forces do not strain the flushing chamber in the front part of the rock drilling machine. The structure of the flushing chamber then need not be dimensioned on the basis of the supporting forces. The structure of the flushing chamber may therefore be lighter and smaller in size, which facilitates its detachment and installation when changing the drill shank. In addition, extra strain from the supporting forces is not directed to the joint surfaces of the flushing chamber and the flushing chamber remains tight. When the strains directed to the critical front end of the rock drilling machine are reduced, the strength and reliability of the rock drilling machine improve.

[0018] The idea of an embodiment is that the axial bearing module comprises at least one sleeve-like axial piston.

[0019] The idea of an embodiment is that the axial bearing module comprises only one axial piston.

[0020] The idea of an embodiment is that the axial bearing module comprises two axial pistons having different travelling lengths in the axial direction.

[0021] The idea of an embodiment is that the rock drilling machine comprises a percussion device module that is detachable in one piece from the rock drilling machine. The percussion device module comprises a percussion module frame, percussion member, pressure channels, seals, bearing surfaces, and possible bearing housings, or at least some of the above that are required by the operation of the percussion device. Due to the modular structure, the wearing parts of the percussion device are easy and quick to replace. The percussion device module may conveniently be replaced by a new module, and new seals and bearings may be changed to a detached percussion device module in a repair shop in good conditions. Further, it is possible to change into the rock drilling machine percussion device modules having slightly different operations and properties for different applications and work sites.

[0022] The idea of an embodiment is that the rock drilling machine comprises a percussion device module that is arranged entirely or at least partly inside the axial bearing support.

Brief description of the figures

[0023] Some embodiments of the invention are described in greater detail in the attached drawings, in which Figure 1 is a schematic side representation of a rock drilling unit arranged on a drilling boom,

Figure 2 is a schematic sectional representation of a part of the rock drilling machine according to Figure 3,

Figure 3 is a schematic sectional representation of a rock drilling machine equipped with an axial bearing module and axial bearing support,

Figures 4 and 5 are schematic sectional representations of some alternative rock drilling machine constructions, and

Figure 6 is a schematic, sectional and partial representation of a rock drilling machine that is equipped with a breech-loaded percussion device module and axial bearing module.

[0024] In the figures, some embodiments of the invention are shown simplified for the sake of clarity. Similar parts are marked with the same reference numbers in the figures.

Detailed description of some embodiments of the invention

[0025] Figure 1 shows a rock drilling unit 1 that may be arranged on the drilling boom 2 or the like of a rock drilling rig. The rock drilling unit 1 may comprise a feed beam 3, on which a rock drilling machine 5 is arranged and moved by means of a feed device 4. The rock drilling machine 5 may be fastened to a carriage 36 and may be moved in the stroke direction A and return direction B. In addition, the rock drilling machine 5 comprises a percussion device 6 for generating impact pulses to a drill shank 7 and further through a tool 8 to the rock 9. The tool 8 may comprise one or more drill rods and a drill bit. Alternatively, the tool 8 may be an integral rod, in which case a machine member like the drill shank 7 may be thought to be fixedly connected to its rock drilling machine side end. Thus, a drill shank in this patent application may also refer to the back end of an integral rod or the like, on which the axial bearing may act. Further, the rock drilling machine 5 may comprise a rotating device 10 for rotating the drill shank 7 and tool 8 around its longitudinal axis. The drill shank 7 is arranged to transmit impact, rotation and feed forces to the drilling tooling that transmits them on to the rock 9 being drilled.

[0026] The percussion device 6 may comprise a percussion piston that is moved back and forth by means of a pressure medium and is arranged to strike in the stroke direction A the impact surface on the drill shank 7. Instead of the percussion piston, it is possible to use any other percussion mem- ber or element for generating impact pulses. Impact pulses need not necessarily be generated from kinetic energy, but they may also be generated directly from pressure energy, for example. Further, instead of pressure energy, the energy required for generating impact pulses may also be some other energy, such as electric energy. Thus, it may be stated that the structure and operational principle of the percussion device are not essential issues for the invention being discussed.

[0027] Figures 2 and 3 are sectional representations of a rock drilling machine 5. The rock drilling machine 5 may have one body, in other words, it may comprise one single uniform body 11. The body 11 may be a tubular piece with a percussion device 6, axial bearing 18, rotating device gear system 13 and drill shank 7 arranged inside it. The percussion device 6 comprises a percussion member 14 that may be a percussion piston arranged to move in the axial direction back and forth by means of pressure medium, for example, so that the impact surface 15 at the front end of the percussion member 14 is arranged to strike the impact surface 16 at the back end of the drill shank 7. It should be mentioned that in this patent application, the front end of the components of the rock drilling machine 5 refers to the stroke-direction A side end and, correspondingly, the back end of the components refer to the return- direction B side end. Surrounding the drill shank 7, there may be a rotating sleeve 17 belonging to the gear system 13 for transmitting the rotation torque provided by the rotating device 10 to the drill shank 7. The connection between the drill shank 7 and rotating sleeve 17 allows the drill shank 7 to move in the axial direction. An intermediate gear 70 may be positioned between the rotating device 10 and rotating sleeve 17.

[0028] The axial-direction position of the drill shank 7 may be acted on by an axial bearing 18 that may comprise one, two, or more pistons movable in the axial direction. The drill shank 7 may be supported from its rear side by means of a first axial piston 19. The axial piston 19 may be arranged to act on the drill shank 7 directly or through a support sleeve 90. The first piston 19 may be a sleeve-like piece that may be arranged around the percussion member 14. Further, a sleeve-like second axial piston 20 may be positioned around the first piston 19. The pistons 19 and 20 may be moved in the axial direction relative to each other, when pressure fluid pressure is directed into their pressure chambers. The movement of the second piston 20 in the stroke direction A may be dimensioned shorter than that of the first piston 19. The movement of the first piston 19 in the stroke direction A may be dimensioned so that the impact surface 16 of the drill shank may be moved to be in front of the planned impact point, when feed resistance becomes smaller, whereby a damper in connection with the percussion member 14 may reduce the strike force transmitted to the tool 8 when soft rock is drilled, for instance. Further, the common force of the axial pistons 19, 20 in the stroke direction A may be dimensioned to be greater than the feed force. Alternatively, the force effect of one axial piston alone is dimensioned greater than the feed force. With the axial pistons 19, 20, it is possible not only to influence the axial position of the impact point but also dampen the return movement caused by the stress pulses returning from the rock. When the above-mentioned return movement is directed to the axial pistons 19, 20, the pressure fluid releasing from the pressure chambers of the pistons is led through suitable throttle means to provide the damping. As regards the general operational principle and structure of the axial bearing, we refer to what is stated in publications Fl 84 701 , Fl 20 030 016, and US 6 186 246 and declare that the matters stated therein are also included in this patent application.

[0029] In the solution of Figures 2 and 3, the axial bearing 18 comprises an axial bearing module 21 installed inside the body 11 through the front end of the rock drilling machine, that is, the module is front-loaded. The axial bearing module 21 is arranged inside the back part of an elongated and in shape essentially sleeve-like axial bearing support 22. In the front end or along the front end of the axial bearing support 22, there may be a fastening flange 23, shoulder or a corresponding support surface, from which it is fastened to the body 11 , preferably to the end surface of the body. At the back end of the axial bearing support 22, there is a cartridge housing 24, into which a module frame part 25 is arranged; this part, too, being an elongated piece and essentially sleeve-like in shape. In the stroke direction A, the cartridge housing 24 is defined by a shoulder 26, against which the module frame part 25 is arranged. It is also possible that the fixed shoulder 26 is substitute by a replaceable sealing sleeve. The module frame part 25 comprises any necessary pressure medium channels 27 for directing the pressure medium into the working pressure chambers 28 of the axial pistons 19, 20 acting in the stroke direction A. The module frame part 25 forms together with the axial pistons 19, 20, bearings 29, bearing housings, and seals 37 an axial cartridge 30 that is arranged in the cartridge housing 24 before the axial bearing support 22 is arranged in place in the space in the body 11. The axial bearing support 22 and axial cartridge 30 may be conveniently detached as one piece after the flushing chamber 31 , drill shank 7, and rotating sleeve 17 in the front part of the rock drilling machine 5, and the intermediate gear 70 are first detached in front of them. The detachment and installation of the above-mentioned components do not require any special skills or special tools. The body 11 need not be dismantled and, therefore, the rock drilling machine 5 need not be detached from the carriage 36 or the like on the feed beam.

[0030] Supporting forces FA caused by the operation of the axial pistons 19, 20 and acting in the stroke direction are transmitted from the axial cartridge 30 through the axial mating surfaces 81 in the shoulder 26 to the axial bearing support 22 and then on through its fastening flange 23 or the like to the body 11. The fastening flange 23 may be fastened with fastening bolts 32 to the end surface or the like of the body 11. In addition, the fastening bolts 33 or corresponding fastening members of the flushing chamber 31 may participate in fastening the axial bearing support 22.

[0031] Differing from Figures 2 and 3, it is possible to use breech- loading, in which the fastening flange 23 of the axial bearing support 22 is supported against an end surface or the like in the back part of the body 11 , and in which the axial cartridge 30 is at the drill shank 7 side end of the axial bearing support 22.

[0032] Figures 2 and 3 further show that the pressure medium channels 27 leading to the axial bearing 18 may be axial at least at the point of contact 34 between the axial cartridge 30 and body 11. Owing to this, the pressure medium channels 27 may be furnished with axial seals 35 that seal the channels when the axial bearing module 21 is pushed in place inside the body 11.

[0033] The axial cartridge 30 also comprises all other necessary seals 37. When the axial cartridge 30 is replaced, all bearings 29, bearing housings, and seals 37 directly affecting the operation of the axial bearing 18 will also be replaced. Figure 2 shows that between the shoulder 26 and first piston 19, there may be a seal 37a, and between the second module frame part 25 and first piston 19, there may be a seal 37b. The seal 37c of the percussion member 14 may also be arranged at the axial cartridge 30, in which case its replacement, too, may take place at the time of the axial bearing module 21 replacement. It is clear that the axial bearing 18 may also comprise other seals and that the sealing may be arranged otherwise than shown in Figures 2 and 3.

[0034] Figure 2 shows the points, at which the supporting forces caused by the operation of the axial bearing are transmitted to the body 11. The supporting forces FA acting in the stroke direction are transmitted by means of the fastening flange 23 and the supporting forces FB acting in the return direction are transmitted by means of the shoulder 74.

[0035] In some cases, in the embodiment according to Figures 2 and 3, it is also possible to use, instead of a one-piece body 11 , a body made up of two or more body parts, but then the point of contact between the body parts is preferably located so that the supporting forces caused by the operation of the axial bearing 18 will not pass the point of contact between the body parts. Thus, the point of contact should reside outside the section between points FA and FB. This way, it is possible to avoid loading the points of contact and the fastening bolts of the body parts.

[0036] The rock drilling machine shown in Figure 4 comprises a construction similar to that of Figures 2 and 3. However, the difference lies in that the axial bearing module 21 is not entirely inside the axial bearing support 22.

[0037] Figure 4 further shows some special features associated with sealing. The pressure channels 27 extending from the body 11 to the axial bearing module 21 are arranged to cross the point of contact 34 between the module 21 and body 11 in the axial direction, whereby there may be axial seals 35 between the connecting channel sections 27, 27a, and 27b. When the rock drilling machine 5 is pressurised and pressure medium is led from the pressure medium channel 27b to a pressure chamber between the second axial piston 20 and second module frame 25, where there is a pressure surface 47 acting in the return direction B, a force is formed therein that tries to push the second module frame 25 in the return direction B against the body 11 with the result that the axial seals 35 at the point of contact 34 press tightly against the sealing surfaces. Further, between the axial bearing support 22 and the module frame 25, there may be an axial spring member 48 that continuously presses the axial cartridge 30 against the body 11. The axial spring member 48 may be for instance an o-ring or corresponding piece made of compressible elastic material. Alternatively, it may be a metal spring. [0038] Figure 5 shows a rock drilling machine 5, in which a second body part 11 b is arranged against a joint surface 50 in the front part of a basic body, that is, a first body part 11 a. The body parts 11 a and 11 b may be fastened to each other with fastening bolts 51. An axial bearing 18 is positioned at the second body part 11 b. The supporting forces FA and FB caused by the operation of the axial bearing are transmitted to the second body part 11 b and by means of it on to the basic body, that is, the first body part 11a. The second body part 11 b is a uniform piece with no joint surfaces between points FA and FB. The uniform second body part 11 b is therefore capable of receiving the supporting forces FA and FB acting in opposite directions. At the front end of the second body part 11 b, there may be an end surface, flange or corresponding support surface 92, to which the axial bearing support 22 may be supported and fastened with fastening bolts 32. The axial bearing module 21 and axial bearing support 22 are arranged in a space in the second body part 11 b after the flushing chamber 31 and the rotating components of the gear system 13 have been detached. The axial module 21 and axial bearing support 22 may be removed and installed through the front end of the rock drilling machine 5 without needing to open the joint surface 50 between the second body part 11 b and first body part 11 a. In this embodiment, the axial bearing support 22 and axial bearing module 21 are arranged axially one after the other and not within each other as in the previous figures.

[0039] Figure 5 further shows some features associated with sealing. The axial bearing module 21 may be pressed by means of a pretension screw 52 against a joint surface 34 of the second body part 11 b in the return direction B, whereby the axial seals 35a at the connecting points of the axial pressure medium channels 27 and 93 achieve good sealing. The joint surface 50 may also have axial seals 35b that seal the channels 27 and 93 when the body parts 11a and 11 b are pressed against each other by means of fastening bolts 51. Otherwise, the embodiment shown in Figure 5 may comprise features shown in other figures of this patent application.

[0040] Figure 6 shows a rock drilling machine 5 that comprises a breech-loaded axial bearing module 21 , axial bearing support 22, and percussion device module 53. The back end of the body 11 has a space or cartridge housing, to which the axial bearing support 22 is arranged. Further, the axial bearing module 21 and percussion device module 53 are arranged inside the axial bearing support 22. The components 21 , 22, and 53 may be detached and installed after the pressure accumulator 61 belonging to the percussion device 6 is first detached. When there is no pressure accumulator or it is positioned elsewhere, there is instead a back cover or some other drilling machine back component which is then detached to obtain access to the components 21 , 22, and 53. The components 21 , 22, and 53 may thus be installed in the space reserved for them inside the body 11 at the same time from one installation direction.

[0041] The body 11 of the rock drilling machine 5 may be a one-part piece, as shown in Figure 6, or in some cases it may comprise two or more body parts attached to each other with a joint so positioned that the supporting forces caused by the axial bearing 18 will not load the joint. In the section of the back end of the axial bearing support 22, there may be a fastening flange 23, shoulder or corresponding member, with which it may be fastened to the end surface or corresponding fastening surface of the body 11. The supporting forces FB caused by the axial bearing 18 may be transmitted by means of the fastening flange 23 directly to the body 11. The axial bearing module 21 may have in its front part a sealing sleeve 54 that may comprise a seal 37 for sealing the first axial piston 19. Further, the body 11 may have a shoulder 55 which limits the cartridge housing and against which the axial bearing module 21 may be supported in the stroke direction A.

[0042] The percussion device module 53 is arranged inside the back part of the axial bearing support 22, and between the two, there may be the necessary seals. The percussion device module 53 comprises a percussion module frame 56 that may be a sleeve-like elongated piece. In addition, the percussion device module 53 may comprise the required bearings 57, seals 58, pressure medium channels 59, and a percussion member 14. The back part of the percussion device module 53 may have a seal sleeve 60. When the pressure accumulator 61 or back cover has been detached by opening the fastening bolts 80, it is then possible to detach only the percussion module 53, if desired, for replacing the seals of the percussion member 14, for instance. Further, the fastening bolts 32 of the axial bearing support 22 may be opened and the components 21 , 22, and 53 pulled out in one piece from the cartridge housing in the body 11. After this, the sealing sleeve 60 may be detached and the percussion member 14 and percussion device module 53 pulled out of the axial bearing support 22. [0043] The stroke-direction supporting forces FA caused by the operation of the axial bearing 18 are transmitted to the body 11 by means of the shoulder 55, and the return-direction supporting forces FB are transmitted to the body 11 by means of the fastening flange 23, as illustrated in Figure 6.

[0044] It should be mentioned that the module frame may be equipped with a bearing that is made of bearing metal, such as bearing bronze, and arranged in the module frame by welding or casting, for instance. The module frame then does not have an actual bearing housing for the separate bearing member, but it has a type of integrated structure. Further, it is possible to form the required bearing surfaces by using a suitable coating. The bearing surface of the axial bearing module may thus be formed of a separate bearing piece, a slide bearing integrated into the module frame, or a bearing coating.

[0045] In some cases, the features disclosed in this patent application may be used as such, regardless of other features. On the other hand, the features disclosed in this patent application may, when necessary, be combined to form various combinations.

[0046] The drawings and the related description are only intended to illustrate the idea of the invention. The invention may vary in detail within the scope of the claims.