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 invention also relates to an axial bearing module. The field of the invention is defined in more detail in the preambles of the independent claims 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 and axial bearing module.

[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; that the outer surface of the module frame is equipped with at least one fixed support member for transmitting the supporting forces caused by the operation of the axial bearing directly from the axial bearing to the body of the rock drilling machine; and that the body of the rock drilling machine is at least at the axial bearing a uniform piece without joint surfaces.

[0005] The axial bearing module of the invention is characterised in that the axial bearing module comprises at least one axial piston, at least one seal, at least one bearing surface, and a module frame; that the axial bearing is a uniform piece that is detachable and installable in place into the rock drilling machine in one piece; and that the module frame is a sleeve-like piece and comprises on its outer rim at least one locking bracket for fastening the axial bearing module independently to the rock drilling machine.

[0006] 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 the 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. Further, the supporting forces caused by the operation of the axial bearing are transmitted directly to the uniform body part of the rock drilling machine by means of at least one locking member in the module frame. Said uniform body part does not have any joint surfaces at the axial bearing.

[0007] 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. 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 the repair shop in good conditions. Because supporting forces are transmitted from the axial bearing module to one uniform body part, there are no joint surfaces at the axial bearing. This way, it is possible to avoid the problems that occurred in the prior-art solutions and were 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.

[0008] The idea of an embodiment is that the body of the rock drilling machine is one single uniform piece with no joint surfaces. A one-piece structure does not have joint surfaces and tie bolts between parts thereof, to which loads are 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. It should be noted that 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.

[0009] 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.

[0010] 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.

[0011] The idea of an embodiment is that the axial bearing module is arranged in place from the front end of the rock drilling machine. Support members in the module frame are then arranged to transmit the axial supporting forces caused by the axial bearing and acting in the stroke direction directly to the body of the rock drilling machine. Thus, the support members transmit at least the supporting forces that are opposite to the installation direction.

[0012] The idea of an embodiment is that the axial bearing module is arranged in place from the back end of the rock drilling machine. Support members in the module frame are then arranged to transmit the axial supporting forces caused by the axial bearing and acting in the return direction directly to the body of the rock drilling machine. Thus, the support members transmit at least the supporting forces that are opposite to the installation direction.

[0013] The idea of an embodiment is that the support members in the module frame are arranged to transmit the supporting forces caused by the axial bearing both in the stroke and return directions.

[0014] The idea of an embodiment is that one or more axial bearing modules are fastened to the body of the rock drilling machine by means of one or more form-locking members. The form-locking member is formed in the module frame.

[0015] The idea of an embodiment is that one or more axial bearing modules are fastened to the body of the rock drilling machine by means of bayonet-fastening.

[0016] The idea of an embodiment is that the module frame of at least one axial bearing module is furnished with at least one support surface, support shoulder, support flange or corresponding member, with which the supporting forces caused by the operation of the axial bearing may be transmitted directly to the body of the rock drilling machine. The support shoulder in the module frame may then transmit the supporting forces in a first direction and the support surface may transmit the supporting forces in a second, opposite direction.

[0017] The idea of an embodiment is that the axial bearing comprises at least two axial bearing modules arranged one after the other in the axial direction. The frame of each module may comprise its own support brackets or the like.

[0018] The idea of an embodiment is that the axial bearing comprises at least two consecutive axial bearing modules, of which the module installed last, that is, the outermost module is arranged to lock the other modules in place in the axial direction. The module frame of the outermost module is furnished with a locking bracket that transmits supporting forces to the body and locks the modules in place.

[0019] The idea of an embodiment is that the outer surface of the module frame is furnished with a thread that is arranged to lock into the body of the rock drilling machine, when the module frame is turned around its centre axis. The thread then acts as a locking member that may transmit at least the supporting forces opposite to the installation direction to the body of the drilling machine.

Brief description of the figures

[0020] 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,

Figures 4 to 7 are schematic, sectional, and perspective representations of the structure of an axial bearing module of the invention and its installation and locking on to the body of a rock drilling machine, and

Figure 8 is a schematic and sectional representation of a rock drilling machine that is equipped with the axial bearing module of Figures 4 to 7.

[0021] 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

[0022] 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.

[0023] 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 member 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.

[0024] The construction and operation of the rock drilling machine and axial bearing are described in general by means of Figures 2 and 3. An embodiment of the invention is shown later in Figures 4 to 8. However, it should be mentioned that the features mentioned in the description of Figures 2 and 3 may also be applied to the solution of the invention as necessary.

[0025] The rock drilling machine 5 shown in Figures 2 and 3 has one body, in other words, it comprises 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.

[0026] 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 pres- sure 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.

[0027] 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.

[0028] Figures 4 to 8 show an alternative axial bearing 18 of the invention that comprises a first axial bearing module 21a and a second axial bearing module 21 b that are arranged consecutively in the axial direction inside the body 11 from one installation direction, in this case from the front end of the rock drilling machine 5, after the flushing chamber 31 , drill shank 7, rotating sleeve 17 and other possible components in front of the axial bearing 18 have been detached. The body 11 that in Figures 4 to 7 is shown only partly for the sake of clarity is at least along the section of the axial bearing 18 a uniform piece with no joint surfaces that the supporting forces caused by the axial bearing 18 could load. As can be seen more clearly in Figure 8, the first axial bearing module 21 a comprises a module frame 38a, axial piston 39a, bearings 40a, bearing housings 41a, and a seal 42a. The first axial bearing module 21 a may be installed in place and detached in one uniform piece. After the first axial bearing module 21 a is pushed in place, the second axial bearing module 21 b may be arranged in the same installation direction in the manner shown in Figure 4. It is also possible to install and remove the axial bearing modules 21a and 21 b together simultaneously. The second axial bearing module 21 b correspondingly comprises a module frame 38b, axial piston 39b, bearing 40b, bearing housing 41 b, and seal 42b. Both axial bearing modules 21 a, 21 b are thus pieces that are easy to handle, detach and install. As can be seen in Figure 4, the module frame 38b of the second axial bearing module 21 b may comprise one or more locking brackets 43 that may be pushed inside openings 44 in the body 11 during installation. When the second axial bearing module 21 b is then turned in the manner shown in Figure 5 around its longitudinal axis at a limited angle, the locking brackets 43 move away from the openings 44 and lock against the locking surfaces or shoulders 65 on the body 11. The fastening of the second axial bearing module 21 b may thus be by bayonet- locking. Naturally, it is also possible to use other fixed form-locks formed on the body or other integral fastening members. The second axial bearing module 21 b also locks the first axial bearing module 21 a in place, whereby the first axial bearing module 21 a need not necessarily be furnished with fastening members, though this is naturally possible. The supporting forces FA and FB caused by the operation of the axial bearing 18 are transmitted by means of the locking bracket 43 or corresponding fastening means and the shoulder 74 directly to the body 11 of the rock drilling machine.

[0029] Figures 6 and 7 show that the rotation of the second axial bearing module 21 b around its longitudinal axis may be prevented with a bearing sleeve 45. The bearing sleeve 45 may comprise axial-direction brackets 46 at the openings 44 in the body 11. When the bearing sleeve 45 is pushed in place in the axial direction, the brackets 46 push into the openings 44 and lock the second axial bearing module 21 b against turning. In the cross-sectional view of Figure 8, this locking arrangement is not visible. The bearing sleeve 45 may comprise a bearing for fitting the rotating sleeve 17 with bearings.

[0030] One embodiment of the axial bearing 18 shown in Figures 4 to 8 may be one with only one axial bearing module 21. Further, another embodiment may comprise one or two axial bearing modules 21 a, 21 b that are mounted in the space in the body 11 through the back end of the rock drilling machine 5, that is, breech-loaded. Further, both axial bearing modules 21 a, 21 b may be equipped with their own locking brackets or corresponding support members for transmitting supporting forces to the body of the rock drilling machine.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.