WO2001083170A1

WO2001083170A1 - Method and arrangement for adjusting the percussion energy in a percussion drilling apparatus

Info

Publication number: WO2001083170A1
Application number: PCT/FI2001/000396
Authority: WO
Inventors: Pekka Salmi
Original assignee: Oy Robit Rocktools Ltd
Priority date: 2000-04-28
Filing date: 2001-04-25
Publication date: 2001-11-08
Also published as: FI121622B; AU2001256395A1; FI20001003A; FI20001003A0

Abstract

The invention relates to an arrangement and a method for guiding drilling in a drilling machine, whose hammer gear, fitted in a frame (1), comprises a percussion piston (2) which reciprocates in the axial direction (X) and, to perform drilling, continually strikes a percussion point (11) in a drill shank (3) fitted in the frame (1). To guide the stroke transmitted to the drill shank (3) and to control the percussion energy in different drilling situations, the operating position of the hammer gear (2) in relation to said percussion point (11) is changed by moving said hammer gear in the axial direction (X). The percussion piston (2) is at least partly fitted within a tubular sleeve (10), movable in the axial direction, wherein the functional position of said hammer gear is changed by moving said sleeve (10) in relation to the frame (1).

Description

Method and arrangement for adjusting ttie percussion energy in a percussion drilling apparatus.

A method and an arrangement in a percussion drilling apparatus

The invention relates to a method according to the preamble of claim 1 for the control of drilling in a drilling machine. The invention also relates to an arrangement in a drilling machine according to the preamble of claim 6.

In rock drilling, jamming of the drilling equipment may occur in a known manner at the stage of drilling a cleavage or a crush in the rock or when the drill bit and the drill rods are pulled out of the ready drill hole. The frame of a rock drilling machine is provided with a drill shank, to which the drill rod with extension rods is fixed and which is continually struck by the percussion piston during the drilling. At the same time, the drill shank can also be rotated by an apparatus fitted in the drilling machine. In a lifting motion, the drill shank is simultaneously moved farther from the percussion piston and away from the so-called percussion point. The drill shank is movable in relation to the percussion piston in the frame so that the stroke is transmitted to the drill rod and further to the drill bit. However, the drilling device can be released by continuing the percussions when the drill shank is lifted by means of a separate transfer apparatus fitted in the frame, wherein the vibration caused by the percussion releases the drill bit. One lifting device equipped with pistons is presented in patent publication FI 102202 B, to which corresponds application publication WO 98/42481 , and a movable drill shank is presented in patent publication US 4,582,145. The drill shank can also be equipped with damping elements, as presented for example in patent publication US 5,002,136. Also, to release a jammed drilling device, an apparatus according to patent publication US 4,718,500 is known, in which the pressure of an external liquid accumulator is increased by the effect of a percussion piston. The pressure will then cause a percussion of the drill shank backwards towards the percussion piston. By means of the percussion, the jammed drilling device can be released.

A problem with prior art transfer devices for drill shanks is their complexity, which causes problems e.g. in the mounting and in the sealings. Another problem is that jamming situations and, for example, rock qualities vary, wherein the percussion energy transferred to the drill shank and further to the drill rod during the releasing should also be controllable in a way as optimal as possible. It is difficult to arrange the damping, the lifting motion and the return stroke simultaneously in the drill shank.

The aim of the invention is to present a method and an arrangement in a percussion drilling device, particularly in a rock drilling machine, whereby the above-mentioned problems can be avoided. To attain this purpose, the method according to the invention is primarily charac- terized in what will be presented in the characterizing part of claim 1. The arrangement in a drilling machine according to the invention is primarily characterized in what will be presented in the characterizing part of the appended claim 6.

An important principle in the invention is that the reciprocating percussion piston is fitted in the frame of the drilling machine in such a way that its position in relation to the percussion point can be changed. The percussion piston is preferably fitted in a sleeve which is moved in relation to the frame of the drilling device, preferably by means of the pressure of a pressurized medium. To achieve a compact structure, said sleeve is provided with the necessary surfaces which are subjected to the pressure effect of the pressurized medium, and the sleeve is used as a kind of a piston. Between the frame and the sleeve, the necessary displacements are formed for the pressurized medium.

One very important feature of the invention is, in a jamming situation, to store the percussion energy directed in the normal drilling direction and to return it as a backwards percussion movement of the drill shank used as a tool, wherein percussion movements are possible when feeding upwards. According to an advantageous embodiment, the drilling device is provided with a spring element operating without external control and storing the percussion energy by compression. The arrangement is particularly useful in connection with a hammer gear with an adjustable operating position, to achieve optimal drilling in different drilling situations. Such drilling situations include starting, when a small energy consumption is required, normal drilling, cleavage and crushing situations, and jamming of the drill rod.

The invention can be used to considerably simplify the positioning of different devices related to the drill shank. Another considerable advantage of the controllable hammer gear is the possibility to optimize the drilling procedure also when drilling forward and particularly when starting the drilling. Simultaneously with moving the sleeve, the position of the damping device of the percussion piston in relation to the percussion point is also adjusted, wherein a desired part of the percussion force can be directed to be damped. This is particularly useful when drilling different rock qualities or when considering, for example, the qualities of the drill rod or the drill bit.

By means of the invention, it is possible to eliminate separate devices for lifting the drill shank. When pulling the jammed drilling equipment backwards, the drill shank is moved farther away from the percussion piston within the frame, and even beyond the percussion, but by moving the hammer gear in the same direction, the percussion movement can be continued to release the drill rods. By means of the invention, the percussion piston can be moved farther and away from the percussion point also in a normal situation. The hammer gear, with its sleeve and channelling, forms an easily replaceable cartridge-like unit. In the invention, the transfer is directed to the hammer gear and its operating position.

The invention will be described in more detail by means of an advantageous embodiment with reference to the appended drawings, in which

Fig. 1 a shows the rear part of a drilling device in a cross-sectional view seen from the side, when the drill shank is pushed forward and the hammer gear, with its sleeve, is transferred backwards,

Fig. 1 b shows the front part of the drilling device of Fig. 1 a, Fig. 2a shows the rear part of the drilling device of Fig. 1 in a cross- sectional view seen from the side, when the drill shank is pushed forward and the hammer gear, with its sleeve, is transferred forwards, and

Fig. 2b shows the front part of the drilling device of Fig. 2a.

Figures 1a and 1b show a drilling device according to a preferred embodiment of the invention, particularly a drilling machine used for rock drilling. The front and rear parts of the drilling machine are divided into Fig. 1a and Fig. 1b, respectively. The drilling device is substantially rotationally symmetrical with respect to its longitudinal axis X, and the spaces for a pressurized medium are substantially annular. The drilling device comprises a frame 1 consisting of a rear frame 1 a and a front frame 1b, connected to each other. The drilling machine also comprises a separate head part 1c in the front frame 1b. A rod-like percussion piston 2 reciprocates within the frame 1 and strikes, at its end 2a on the side of a drill shank 3, continually the rear end 3a of the rod-like drill shank 3. Further, drill rods and a drill bit are connected to the opposite end, i.e. the front end 3b, of the drill shank 3 used as a tool, in a way known as such. The percussion energy is transmitted by them to the material to be drilled, for example a rock.

A rotating bushing 4 is fitted around the rear end 3a of the drill shank, and its outer surface is provided with an axial cogging 4a. A cogged wheel 5a of a rotating device 5 is arranged in functional contact with the cogging 4a and is arranged to rotate the drill shank 3 around the longitudinal axis X at a given speed, when necessary. The rotating device 5 comprises, for example, a motor fitted in the frame 1 and driven by a pressurized medium, to rotate the cogged wheel 5a around its axis Y. An external cogging 3c formed in the drill shank 3 is interlaced with the internal cogging 4b of the rotating bushing 4. The drill shank 3 and the rotating bushing 4 rotate together at the same speed, but the movement of the drill shank 3 with respect to the rotating bushing 4 in the direction of the axis X is allowed, thanks to the axial coggings 3c and 4b. The reciprocating motion of the percussion piston 2 is produced by the pressurized medium which is supplied to the percussion piston 2 via channels provided in the frame 1. The pressurized medium, for example a hydraulic fluid, enters an inlet channel 6, and the force of its pressure has an effect on an annular surface 2b formed on the percussion piston 2. The force effect of the pressure moves the percussion piston 2 forward. In the reverse stroke, the medium exits via a backward channel 7. The reciprocating percussion movement is produced in a way known as such, for example by valve means (not shown in the figures) coupled to the pressure supply, coupled to the frame 1 by means of hoses or tubes. The valves can also be integrated and fixed in the frame 1. The channels 6, 7 and 8 are led (not shown in the figures) to the end or the sides of the frame 1 by drillings. The reverse stroke is produced by means of pressurized medium supplied to a channel 8, the pressure being effected on the annular surface 2c of the percussion piston 2. The force effect of the pressure moves the percussion piston 2 backward. The channels 6, 7 and 8 are annular around the sleeve 10. It should be mentioned that the annular surface can consist of several designed, arch-like surfaces. The arched surface primarily refers to the surface of the sleeve in general, which is subjected to the force effect of the pressurized medium and which is preferably annular and centrally placed on the axis X.

In connection with the annular surface 2c there is also an annular space 9 in which the pressurized medium acts as a damping cushion when the percussion piston 2 strikes to the end of its travelling length. The space 9 is formed between the percussion piston and the sleeve 10. The pressurized medium compressed in the space 9 decelerates the percussion piston 2 and receives its motion energy. Pressurized medium is discharged from the space 9 via an opening between the percussion piston 2 and the sleeve 10, and finally from a sealing opening to the channel 8. When the front end 2a of the percussion piston 2 strikes the rear end 3a of the drill shank which determines the so-called percussion point 11 , at least part of the effect of the stroke is received by the pressurized medium in the space 9 or by the drill shank. As a result, the position of the percussion piston 2 in relation to the percussion point 11 , as well as their position in relation to the damping or the space 9, constitute an important functional factor in view of optimization of the drilling.

As shown in Figs. 1a and 1b, the percussion piston 2 is fitted within the sleeve 10 which is movable with respect to the frame 1 and in which the percussion piston 2 then effects its reciprocating percussion movement. Furthermore, the sleeve 10 is provided with a damping space 9 as an annular and step-shaped surface. For example, to facilitate the mounting of the bushing fitted around the rear end 2d of the percussion piston, in connection with the channels 6 and 7, the sleeve structure 10 consists of at least two tubular parts 10a and 10b fitted one after the other. The percussion piston 2 extends through the part 10a, and the part 10b also covers the rear end 2d of the percussion piston. The sleeve 10 is movably fitted in the cylindrical space of the frame 1. To secure the mounting of the parts of the sleeve 10, e.g. their placement centrally on the axis X, and to facilitate the manufacture of the cylinder surfaces as well as to mount the percussion piston 2 with its sleeve 10 in an integrated piece, the parts 10a and 10b are fitted inside the tubular sleeve part 10c. In the presented embodiment, the percussion piston 2 protrudes from the sleeve 10, at least at its front end 2a. The cylindrical surfaces between the sleeve 10c and the frame 1 are further used as bearing surfaces. The parts 10a, 10b and 10c move together, connected to each other. The parts 10a, 10b and 10c can also form a single integrated piece. A channel 6a leading to the percussion piston 2 is formed through the sleeve 10, for example a radial drilling which is arranged to remain in a continuous contact with the channel 6 even in different positions of the sleeve 10. Correspondingly, channels 7a and 8a are arranged in connection with the channels 7 and 8, respectively.

To move the sleeve 10, it is provided with opposite annular surfaces 10d and 10e which are subjected to the force effect of the pressurized medium. The counterforce is produced by means of counter surfaces of the frame 1 or parts fixed to it. Through a channelling 12a in the frame 1 , for example a longitudinal drilling, pressurized medium is led to the annular space 12, wherein the sleeve 10 moves, together with the reciprocating percussion piston 2, backwards to the position shown in Figs. 1a, 1b. At the same time, medium is discharged from the space 13. The sleeve 10 is used as a kind of a piston, and the spaces 12, 13 are used as variable displacements, between which the sleeve 10 moves with the percussion piston. The sleeve 10 moves forward to the position of Figs. 2a and 2b, when medium is led through a channelling 13a in the frame 1 , for example a longitudinal drilling, into the space 13, wherein the sleeve 10 moves forward with the percussion piston 2. At the same time, medium is discharged from the space 12. The channellings are led, for example, to connectors on the rear surface 1d of the frame. The control can be performed by valve means, for example a directional valve, controlled by a required control system in a desired way, for example electrically. The valve 10 can also be locked in an intermediate position by closing both the spaces 12 and 13 by the valve means, or by maintaining the position by the valve means in another way. In this context, it is also feasible that the position of the sleeve 10 is measured by sensor means. The control is performed on the basis of the desired optimization and the position data. The details of the control circuit and the valve means are obvious as such for anyone skilled in the art, to be implemented on the basis of the above description, and in this context, it is possible to apply controls known as such. In its simplest form, the sleeve 10 has only the positions shown in Figs. 1a, 1b and 2a, 2b.

The hammer gear, comprising at least the percussion piston 2, with its sleeve 10, channels 6a, 7a, 8a, and damping 9, forms an easily replaceable cartridge-like unit. The more detailed structure of the percussion piston 2 may, naturally, vary, and the number of bushing structures related to it, as well as the number of valves and valve channellings can vary according to how the percussion piston 2 is controlled, for example, in the stroke and reverse directions. The structure of the sleeve 10 is not limited solely to the presented channellings, but it may also comprise other channellings to control the pressurized medium between the valve means and the percussion piston. The sleeve 10 may comprise several annular surfaces, if necessary.

When pulling back the jammed drilling device, the drill shank 3 is placed in the position of Fig. 1 b, in which its shoulder surface 3d is supported against a bushing 14 and further from the percussion piston 2. The travelling distance of the drill shank 3 is typically about 1 to 2 mm in a percussion situation. In the position of the sleeve 10 shown in Figs. 1a, 1b, the stroke would not extend to the percussion point 11 because of damping of the space 9, for which reason the sleeve 10 is moved to the position of Figs. 2a, 2b. The possible travelling distance of the sleeve 10 is about 20 mm or more. It is thus possible to hit the percussion point 11. The annular bushing 14, placed around the drill shank 3 and in front of the shoulder surface 3d, is, in turn, supported to a spring element 15 in front of it. In an advantageous embodiment, the spring element 15 consists of several annular cup springs placed against each other. Further, the spring element 15 is supported at its front part to the frame 1. The frame 1 is, around the drill shank 3, also provided with a scavenging device 16, known as such.

The spring element 15, operating without external control, stores the percussion energy by compressing against the frame 1 in the direction of the axis X. The percussion energy is stored as potential energy in the spring element, because, in a jamming situation, the drill bit cannot strike forward into the material to be drilled. The spring element 15 returns the percussion energy by returning backwards to its original dimension, wherein it simultaneously strikes and moves the drill shank 3 by means of the bushing 14. Thus, the drill bit strikes backwards, simultaneously releasing the drilling equipment which was jammed by drilling. When drilling forwards, the drill shank 3 is, in turn, supported at its shoulder surface 3e to the rotating bushing 4 and is placed at a determined distance from the bushing 14. In this situation, the percussion force transmitted to the drill shank 3 can be controlled by changing the position of the reciprocating percussion piston 2 by means of the sleeve 10. In some drilling situations, such as misses, the spring element 15 is used as a damper and stops the drill shank 3. The cup springs of the spring element 15 are selected to have a high spring constant, wherein even a short movement of the drill shank 3 will produce a force which is as great as possible, for a short reverse stroke. This is best achieved by means of cup springs. The mechanical spring element 15, which, to store percussion energy, is changed in its dimensions when subjected to a force, particularly cup springs, have the advantage of independence of an external energy supply or control. Compared to control by pressurized medium, the solution does not involve problems with sealing, which would relate to high pressure strokes in connection with compression of the fluid or impurity of the hydraulic fluid.

The spring element 15 and the bushing 14 are fitted within a tubular sleeve 17 which is, in turn, fitted between the parts 1b and 1c in a stationary manner. The drill shank 3 extends through the spring element 15, the bushing 14 and the sleeve 17, fitted centrally on the axis X. The step on the inner surface of the sleeve 17 restricts the reverse movement of the bushing 14. The space 12 is limited to a tubular bearing bushing 18 which is placed around the end 2a and partly also between the frame 1 and the sleeve 10, particularly the part 10a. Alternatively, the frame 1 can be provided with a ridge-like step to form a space 12 and to form an annular surface for the counterforce. For the mounting, the frame 1 is cut in parts 1a and 1b at the rotating sleeve 4, and also in parts 1 b and 1 c at the spring element 15. Between the sleeve 10 and the percussion piston 2, particularly in connection with the different channels, annular sealings are provided to eliminate leakages. Annular sealings are also provided between the sleeve 10 and the frame 1 to eliminate leaks between the different channels and the different spaces.

The present invention is not limited solely to the above-presented advantageous embodiments used as examples, but it can be modified within the scope of the appended claims. In this context, drilling machines refer particularly to rock drilling devices and also grinding devices, in whose hammer gears the method and arrangement can also be applied. The position of the percussion piston 2 in relation to the percussion point 11 can also be changed by adjusting the distance between the frame parts 1a and 1b, wherein the sleeve 10 is formed by the frame 1 itself. The frame part and the hammer gear are thus transferred together. The device can still be provided with the presented cartridge-like hammer gear with the sleeve 10, but it does not need to move in relation to the frame 1a, but only in relation to the frame around the drill shank. The drill shank 3 and the percussion piston 2 are thus fitted in the frame part 1 b and the frame part 1 a, respectively. The distance is adjusted, for example, by means of axial hydraulic pistons, which are fitted around the axis X in the frame 1 in an annular manner. However, a most compact and more precisely adjustable drilling device can be achieved by using the above- presented sleeve. Also the sleeve 10 can be moved by means of one or more pistons and, if necessary, by means of other pistons in the opposite direction, which pistons are arranged to be effective between the frame 1 and the sleeve 10 in the axial direction. However, the most compact device with the simplest construction is achieved by forming the functions in the sleeve itself. Furthermore, it is obvious that the hammer gear can be constructed without the above-presented rotating device.

Claims

Claims:

1. A method for controlling drilling in a drilling machine, whose hammer gear, fitted in a frame (1), comprises at least a percussion piston (2) which reciprocates in the axial direction (X) and, to perform drilling, continually strikes a percussion point (11) in a drill shank (3) fitted in the frame (1), and means (9) for restricting and damping the movement of the percussion piston (2), characterized in that to control the stroke transmitted to the drill shank (3) and to control the percussion energy in different drilling situations and positions of the drill shank (3), the operating position of the hammer gear (2) in relation to said percussion point (11) is changed by moving said hammer gear in the axial direction (X).

2. A method according to claim 1 , characterized in that at the same time, the operating position of the hammer gear (2) in relation to said frame (1) is also changed accordingly.

3. A method according to claim 1 or 2, characterized in that the percussion piston (2), at least partly, and said means (9) are fitted within a tubular sleeve (10), movable in the axial direction, wherein the operating position of said hammer gear is changed by moving said sleeve (10) in relation to the frame (1 ).

4. A method according to any of the claims 1 to 3, characterized in that the hammer gear (2) is brought closer to the drill shank (3) while the drilling machine is pulled backwards, wherein it is possible to strike the percussion point (11) by means of the percussion piston (2), to release the jammed drilling equipment.

5. A method according to claim 4, characterized in that the percussion energy of the percussion piston (2) is stored in a spring element (5) compressed by means of the drill shank (3), from which spring element it is immediately returned to a reverse stroke of the drill shank (3) as the spring element (5) is returned.

6. An arrangement for a drilling machine, which comprises a hammer gear to be fitted in the frame (1) of the drilling machine, comprising at least a percussion piston (2) which reciprocates in the axial direction (X) and, to perform drilling, is arranged to continually strike a percussion point (11) in a drill shank (3) fitted in the frame (1), and means (9) for restricting and damping the movement of the percussion piston (2), characterized in that to control the stroke transmitted to the drill shank (3) and to control the percussion energy in different drilling situations and positions of the drill shank (3), the operating position of the hammer gear (2) in relation to said percussion point (11) is arranged to be changed in such a way that said hammer gear is arranged to be moved in the axial direction (X).

7. An arrangement according to claim 6, characterized in that at the same time, the functional position of the hammer gear (2) in relation to said frame (1) is also arranged to be changed accordingly.

8. An arrangement according to claim 6 or 7, characterized in that the percussion energy of the percussion piston (2) is arranged to be stored in a spring element (5) compressed by means of the drill shank (3), from which spring element it can be immediately returned to a reverse stroke of the drill shank (3) as the spring element (5) is returned.

9. An arrangement according to claim 8, characterized in that the spring element (5) comprises two or more transverse centrally fitted cup springs of the drill shank (3) which are arranged to be compressed by tensioning when the drill shank (3) moves forward in the axial direction (X).

10. An arrangement according to any of the claims 6 to 9, characterized in that the percussion piston (2) is at least partly fitted within a tubular sleeve (10), movable in the axial direction (X), wherein said operating position of the hammer gear is arranged to be changed by moving said sleeve (10) in relation to the frame (1).

11. An arrangement according to claim 10, characterized in that the sleeve (10) is also provided with said means (9) for restricting and damping the movement of the percussion piston (2), wherein the operating position of said means in relation to said frame (1) is changed accordingly.

12. An arrangement according to claim 10 or 11 , characterized in that channellings (6a, 7a, 8a) are fitted through the sleeve (10) to produce a reciprocating motion of the percussion piston (2), which channels are arranged to joint corresponding channels (6, 7, 8) in the frame (1) also when the sleeve (10) is moving.

13. An arrangement according to any of the claims 10 to 12, characterized in that the sleeve (10) is provided with at least a first annular surface (10e) to move the sleeve by an effective force of a pressurized medium, and that the sleeve (10) is also provided with at least a second annular surface (10d) for moving the sleeve in the reverse direction by the force effect of the pressurized medium.

14. An arrangement according to any of the claims 10 to 13, characterized in that the sleeve (10) comprises a tubular outer bushing (10c) which is fitted, in a sealed and movable manner, in a cylindrical space formed in the frame (1), and an inner bushing consisting of two or more tubular parts (10a, 10b) placed one after the other, inside which the percussion piston (2) is fitted in a sealed and movable manner.