Sensor arrangement and method for measuring contact feed force of a feed beam

Abstract

Sensor arrangement (1) and method for measuring contact feed force between a rock face (100) and a feed beam (5) of a mining or construction rig (50), which rig (50) comprises a boom (4) on which the feed beam (5) is arranged and which feed beam (5) is arranged to shuttle an object (40) back and forth along a feeding direction (Z) of the feed beam (5). The feed beam (5) comprises a rock engaging dowel (20c) at its first end (5a), for engaging the rock face (100), to stabilize the feed beam (5) during operation of the rig (50), wherein the sensor arrangement (1) comprises at least one force sensor, arranged to sense forces applied to the dowel (20c), wherein the at least one force sensor is arranged at the dowel (20c).

Description

SENSOR ARRANGEMENT AND METHOD FOR MEASURING CONTACT FEED FORCE OF A FEED BEAMTechnical field

[0001] The present disclosure relates to a sensor arrangement for measuring contact feed force between a rock face of a rock to be drilled and a feed beam of a mining or construction rig. It further relates to a method for handling forces acting on a rock engaging dowel of a feed beam of a mining or construction rig. Preferably, the sensor arrangement and the method concern a drill arrangement within mining industry.Background

[0002] For example, within mining and rock excavation industry, the mining or construction rigs often carry tools like drills, feed beams, rock hammers, bolting equipment and the like, which are arranged on a boom of the mining or construction rig. The feed beam may be arranged to shuttle an object, like a drill feed, which feeds the drill rod or rock bolts during drilling / bolting. During drilling as well as during other types of processes where the boom and the feed beam are used to engage some tool with the rock / rock face, some kind of counterforce needs to be built up, to be able to for example drill the rock. To handle this counterforce and to create a grip with the rock face, a rock engaging dowel is arranged at the front end of the feed beam. The dowel may be a plate-like pad with some extension in a dowel plane or a “sharp” like a peg or spike and the dowel may also comprise a so-called stinger, which is an extendable and retractable beam, arranged on the boom, wherein the dowel may be arranged at the front end of the stinger. By engaging the dowel with the rock face and then apply a pressure on the dowel, in direction to the rock face, a counterforce is built up. For example, if a counterforce of 1 .0 kN is needed, the operator (or the system) applies a pressure slightly larger, for example 1.1 kN in the feeding direction of the feed beam. The dowel may have a pivotal connection to the feed beam, such that the dowel may adjust a bit to the rock surface, since the rock surface often not is flat. When engaging the dowel with the rock face, the operatortries to apply the dowel such that the extension direction (feeding direction) of the feed beam is as close to a normal direction of the rock face. This is normally performed “manually” and is based on experience of the operator. In reality, the rock face almost never is flat, and it is not easy to make sure that the wanted counterforce is applied in a normal direction to the rock face, which also is aligned with the feeding direction of the feed beam. Thus, the counterforce applied to the dowel may have force vectors in several directions, not only (or at all) in the normal direction, i.e. along the feeding direction of the feed beam the stinger direction, wherein a wanted counterforce of 1 .1 kN in the feeding direction, may be much lower, due to perpendicular or any other side forces. This may lead to so- called “dowel release”, where the dowel slips du to high side forces and a too low force in the feeding directions. Dowel release during operation of the mining or construction rig must be avoided and there is a high demand of a reliable detection of dowel release, to enable robust drilling or bolting operation, especially during automation of the operation. Today, the detection of dowel release is only handled through reading the hydraulic pressure changes in hydraulic cylinders facilitating the operation of the feed beam and / or the stinger, on which the dowel is attached to. This solution is unreliable, and a different method is requested. Furthermore, a dowel release detection only detects the symptom of the issue. The root of the dowel release is high perpendicular forces I side forces acting on the dowel and coming from the boom and feeder. High dowel engagement forces (especially perpendicular forces) are also the root cause for high wear on boom and feeder components.

[0003] In prior art solutions, the dowel release thus happens, and to solve the dowel release, a new angle or position of the dowel is needed, and the boom and feed beam must be reorientated by the operator (or system). This is of course time consuming and might be needed to perform several times during operation of the rig. Since remotely operated mining and construction rigs drill are more and more used, arrangements to solve problems that may occur, must be possible to handle remotely. Thus, there is a need of taking care of the problem of dowel release.Summary

[0004] It is an object of the disclosure to address at least some of the problems and issues outlined above.

[0005] According to one aspect, a sensor arrangement for measuring contact feed force between a feed beam and a rock face of a rock to be drilled is disclosed. The sensor arrangement is arranged for a mining or construction rig and the mining and / or construction rig comprises a boom, arranged on the mining or construction rig, a feed beam, which is arranged on the boom, and which feed beam is arranged to shuttle an object along a longitudinal axis of the feed beam in a feeding direction or a direction opposite to the feeding direction. The object may for example be a drill arrangement or the like. The rig further comprises a rock engaging dowel, which is arranged for engaging the rock face, to stabilize the feed beam during operation of the rig. Typically, during operation, the rig / feed beam has to provide a counterforce to for example the drill operation, to enable a steady pressure on the drill during drilling as well as a steady holding of the drill at the same position. Otherwise, the drill might bounce around on the rock face which is an unwanted behavior. The dowel is arranged at a first end of the feed beam and the dowel has an extension in a dowel plane, that is at least a small or a bigger extension, which may be perpendicular to the feed beam, but may also have other extensions (for example an extension with an angle relative the feed beam. The dowel also is defined by having a normal which is a perpendicular direction relative the dowel plane. The sensor arrangement comprises at least one force sensor, which is arranged to sense forces applied to the dowel, wherein the at least one force sensor is arranged at the dowel.

[0006] By such sensor arrangement, it is possible to measure and register forces in any direction, which forces impact the dowel in any direction, for example along the dowel plane, in the normal direction to the dowel plane, or in any other direction, wherein the knowledge of the forces in all directions acting on the dowel may be used to avoid the so-called dowel release. For example, if high side forces impact the dowel (high forces relative the force in the normal direction), there is high risk of dowel release, and this information may be used in different ways tohandle the situation. The information may be evaluated as force vectors and actions taken the outcome of the force vector information. Referring to the example in the background, where the counterforce applied to the dowel may have force vectors in several directions, and a wanted counterforce of 1.1 kN in the feeding direction of the feed beam is set as a demand for a drilling operation by the drill rig, the counterforce in the feeding direction may be sensed and registered as much lower, due to perpendicular or any other side forces. The risk of dowel release may be stated as high, and one option to solve or minimize the risk of dowel release could be to just increase the pressure in the normal direction to the dowel plane, for example by increase pressure towards the rock face by the feed beam.

[0007] According to a disclosure, the at least one force sensor is arranged to sense forces applied to the dowel at least in one of the normal direction and directions parallel with the dowel plane. This means that simpler and thereby cheaper sensors may be used, compared to a sensor which is able to sense forces in any direction.

[0008] According to a disclosure, the at least one force sensor is a three-axial force sensor arranged to sense the forces at least in the directions parallel with the dowel plane and in the normal direction to the dowel plane.

[0009] According to a disclosure, the at least one force sensor is a first force sensor, a second force sensor and a third force sensor, wherein the force sensors are arranged spaced apart in the dowel plane of the dowel. Preferably, the sensors are arranged symmetrically relative a centre of the dowel plane. By using at least three sensors spaced apart in the dowel plane, any forces acting on the dowel may be sensed since the spacing of the sensors in the plane provides the function of sensing different pressures on the respective sensors in the plane which gives information about both side forces and forces in the normal direction to the dowel plane.

[0010] According to a disclosure, the first, second and third force sensors each are arranged to sense a force in the normal direction to the dowel plane of thedowel. This means that the sensors are positioned in the normal direction to the dowel plane and spaced apart, wherein the sensors may be cost-effective 1-axis sensors, but still sensing both forces in the normal direction and by the spacing of the sensors, differences between the forces which indicates side forces.Preferably, the sensors are arranged symmetrically relative a centre of the dowel plane.

[0011] According to a disclosure, the first, second and third force sensors are arranged to sense forces in mutually different directions. This means that the sensors may be arranged spaced apart and in different direction relative each other. Preferably, the sensors are arranged symmetrically relative a centre of the dowel plane.

[0012] According to a disclosure, the first, second and third force sensors each are arranged with an angle relative to the the normal direction of the dowel plane of the dowel, such that imaginary axes of the force sensors cross each other at a common intersection point. Preferably, the sensors are arranged symmetrically relative a centre of the dowel plane.

[0013] According to a disclosure, the the common intersection point is arranged at the dowel.

[0014] According to a disclosure, the first, second and third force sensors each is a one-axial force sensor, which is a cost-effective way of sensing forces applied to the dowel.

[0015] According to a disclosure, the rig further comprises a stinger, which is arranged on the boom, and the stinger comprises a first end and an opposite second end, wherein the first end comprises the rock engaging dowel. The stinger extends in a stinger direction from its first end to its second end, and the stinger further comprises a first actuator, arranged for extending and retracting the stinger such that a distance between the first end and the second end may be changed. By such a stinger, the feed beam can be remained in its position, wherein the pressure on the dowel in the normal direction of the dowel may be increased bymeans of the stinger. Normally, the normal direction of the dowel plane is the same as the feed beam direction and the stinger direction, or at least a direction close to the normal direction of the dowel, if the dowel has an angle relative the feed beam / stinger direction. Thus, the pressure in the normal direction of the dowel plane increases if the stinger is expanded by the actuator, which saves time since rearranging the feed beam (and / or the complete rig) to increase the pressure and avoid dowel release, takes a lot more time.

[0016] According to a disclosure, the rig further comprises a drill feed, arranged for drilling the hole in the rock, and arranged on the feed beam. The sensor arrangement is particularly well suited for a drill rig with a drill feed, since dowel release during drilling is dangerous and costly, for example since the drill may be jammed in the hole or be broken, if a sudden dowel release happens. This is also dangerous if the rig is maneuvered by a person (operator) on site.2

[0017] According to a disclosure, the rig further comprises a control unit, communicatively connected to the at least one force sensor, wherein the control unit is arranged to determine a compression force acting on the dowel in at least the normal direction of the dowel, based on the forces sensed by the at least one force sensor. Of course, the control unit may be arranged to determine compression forces acting on the dowel in any direction, but the main purpose may be to make sure that the pressure (counterforce) acting on the dowel in the normal direction to the dowel plane is high enough to avoid dowel release and to apply enough pressure towards the rock face during operation of the rig.

[0018] According to a disclosure, the control unit further is arranged to determine a first sideway acting force acting on the dowel in an X-direction and a second sideway acting force acting on the dowel in an Y-direction, wherein the X- direction, the Y-direction and the normal direction are perpendicular to each other. Thus, the forces along the dowel plane and perpendicular to the dowel plane may be monitored and acted on by means of the control unit, for taking further actions on the results.

[0019] According to a disclosure, the control unit further is arranged to trigger adjustment of direction of the feed beam in relation to the sensed forces.

[0020] According to a disclosure, the at least one force sensor is fixedly arranged between the first end of the stinger and the dowel.

[0021] According to an aspect, a method for handling forces acting on a rock engaging dowel of a feed beam of a mining or construction rig, according to any of the preceding embodiments, is disclosed. The method comprises:- bringing the rock engaging dowel of the feed beam into contact with a rock face,- sensing forces applied to the dowel in at least in one of the dowel planes or in the normal direction to the dowel plane.

[0022] By such a method, it is possible to measure and register forces impacting the dowel in at least one direction, wherein the knowledge may be used to avoid dowel release.

[0023] According to a disclosure, after the step of sensing forces applied to the dowel, the method further comprises:- increasing the force applied to the dowel in the normal direction to the dowel plane. This to apply the wanted pressure to create the expected / wanted counterforce of the dowel or if there is risk of dowel release.

[0024] According to a disclosure, the method further comprises:- determining a compression force acting on the dowel in at least a normal direction to the dowel plane of the dowel, based on the forces applied to the dowel and sensed by the at least one force sensor. This to apply the wanted pressure to create the expected / wanted counterforce of the dowel or if there is risk of dowel release.

[0025] According to a disclosure, the method further comprises:- adjusting the direction of the feed beam in relation to the rock face, based on the determined compression force in the normal direction to the dowel plane of the dowel, to avoid dowel release.

[0026] According to a disclosure, when the rig comprises a stinger, and after the step of determining the compression force in the normal direction to the dowel plane of the dowel, the method further comprises:- extending the stinger for increasing the compression force applied to the dowel.

[0027] According to a disclosure, the method further comprises:- determining a first sideway acting force acting on the dowel in an X-direction and a second sideway acting force acting on the dowel in an Y-direction, wherein the X-direction, the Y-direction and the normal direction to the dowel plane, are perpendicular to each other, based on the forces applied to the dowel and sensed by the force sensor,- minimizing any determined first and second sideway acting forces acting on the dowel by adjusting the orientation of the feed beam in relation to the rock face, based on determined first and / or second sideway acting forces.

[0028] According to a disclosure, wherein the minimizing of any determined first and second sideway acting forces comprises minimizing until at least one of the first and second sideway acting forces is below a first threshold value.

[0029] According to a disclosure, wherein if any determined first and second sideway acting forces are above a second threshold value, repeat the steps from the step of applying the rock engaging dowel to a rock face by the feed beam and / or the stinger.

[0030] According to a disclosure, wherein the first threshold value is smaller than second threshold value.

[0031] Further possible features and benefits of this solution will become apparent from the detailed description below.Brief description of drawings

[0032] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

[0033] Fig. 1 shows a side view of a mining rig during operation in a mine shaft, which rig comprises a boom and a feed beam.

[0034] Fig. 2 shows an isometric view of a rock engaging dowel arranged at a first end of the feed beam of the rig, which dowel is arranged for engaging a rock face, for stabilizing the feed beam during operation of the rig.

[0035] Fig. 3 shows an isometric view of an embodiment of the feed beam of the rig in Fig. 1 .

[0036] Fig. 4a-b show a side view and a top view of the dowel of Fig. 2, according one embodiment of the invention.

[0037] Fig. 5a-b show a side view and a top view of the dowel of Fig. 2, according to another embodiment of the invention.

[0038] Fig. 6a-b show a side view and a top view of the dowel of Fig. 2, according to yet another embodiment of the invention.

[0039] Fig. 7 shows a flow chart of a method according to the invention.Detailed description

[0040] In the following, different examples of. The method disclosed herein may be realized in many different forms and should not be construed as being limited to the examples set forth herein. Like numbers in the drawings refer to like elements throughout.

[0041] Fig. 1 shows a side view of a mining rig or construction rig 50 during operation in a mine shaft. The rig comprises a boom 4 arranged on the rig 50, and a feed beam 5, which is arranged on the boom 4. The feed beam 5 comprises a first end 5a and an opposite second end 5b. The feed beam 5 is arranged to shuttle an object (see Fig. 3) along a longitudinal axis of the feed beam 5 in a feeding direction Z or a direction opposite to the feeding direction Z. The first end 5a of the feed beam 5 comprises a rock engaging dowel 20c, which is arranged forengaging a rock face 100 of a rock which is to be drilled, to stabilize the feed beam 5 during operation of the rig 50.

[0042] Fig. 2 shows an isometric view of the rock engaging dowel 20c, when arranged at the first end 5a of the feed beam 5 of the rig, and which dowel 20c is pressed towards the rock face 100 for creating a pressure force, wherein the feed beam 5 is stabilized during operation of the rig 50. Thus, a counterforce F is created and the counterforce F presses towards the dowel. A rock face 100 seldom is flat and “perfect”, but instead rough and often angled relative a dowel plane XY of the dowel 20c. As exemplified in the figure, the counterforce F is in this case angled relative the extension of the dowel plane XY, wherein side forces in any directions A, B, C, as well as forces with a normal direction N to the dowel plane XY occurs. If the side forces are too large it may lead to so-called dowel release, wherein the dowel 20c loosens the “grip”, due to that friction forces between the dowel 20c and the rock face 100 are exceeded by too large side forces. In prior art solutions, an operator or the system, which controls the rig 50, estimates how large the pressure force along the normal direction N, towards the rock face 100, is needed for performing the rig operation (for example drilling).This is done without knowing if high side forces occurs and how large the pressure force along the normal direction N, towards the rock face 100, actually is. If the rock face 100 is uneven, the pressure force may be “spread out”, so to speak. To avoid this and to be able to measure and control the pressure force in the normal direction N, towards the rock face 100, as well as the size of the side forces, the rig comprises a sensor arrangement (not visible). The sensor arrangement 1 comprises at least one force sensor, (not visible), which is arranged to sense forces applied to the dowel 20c, wherein the at least one force sensor is arranged at the dowel 20c.

[0043] Fig. 3 shows an isometric view of an embodiment of the feed beam 5 of rig 50, seen from the first end 5a of the feed beam 5, which first end 5a is a front end of the feed beam 5. Opposite the first end 5a is the second end 5b arranged, and as mentioned above, the feed beam 5 is arranged to shuttle at least one object 40 back and forth along the longitudinal axis of the feed beam 5, which is inthe feeding direction Z and the opposite direction the feeding direction Z. The first end 5a of the feed beam 5 comprises the rock engaging dowel 20c, which in this embodiment is arranged as a pad, with an extension perpendicular to the longitudinal axis direction (the feeding direction Z) of the feed beam 5. Preferably, the dowel 20c is made of rubber. The dowel 20c may be arranged directly to the first end 5a of the feed beam 5, either totally fixed or with some kind of pivotable fixation to the first end 5a, such that the dowel 20c may tilt a bit in one or two dimensions relative the feed beam 5. In the embodiment showed in Fig. 3, a so- called stinger 20 is arranged on the feed beam 5. The stinger 20 is arranged below the feed beam 5 and extends along the feed beam 5 and the stinger 20 comprises a first end 20a and an opposite second end 20b, wherein the first end 20a comprises the rock engaging dowel 20c. The stinger 20 thus extends in a stinger direction from its first end 20a to its second end 20b, and the stinger 20 further comprises a first actuator (not visible), arranged for extending and retracting the stinger 20 such that a distance between the first end 20a and the second end 20b may be changed. By that, the pressure force towards the rock face 100 may be changed not only by pressing the boom 4 with the feed beam 5 towards the rock face 100, but also by extending or retracting the stinger 20, by means of the actuator. This means that the pressure force can be changed without rearranging the boom 41 the feed beam 5, which saves time. The rig further comprises a drill feed 10, which is arranged for drilling the hole in the rock, and the drill feed 10 is arranged on the feed beam 5 and may also be arranged on the feed beam 5 such that it may be shuttled back and forth along the longitudinal axis of the feed beam 5.

[0044] As indicated with force vectors (arrows) in the figure, the counter pressure force F from the rock face, created by the pressure force with the dowel 20c on the rock face 100, may have an angled direction relative the feed beam 5, why the angled force may be sensed by the force sensor (not visible) of the sensor arrangement. Since the force sensor / sensors is / are arranged on the dowel 20c and may sense the counter force F acting on the dowel in any direction, this information may be used to evaluate and calculate a compression force FN acting on the dowel 20c in the normal direction N of the dowel 20c as well as side forcesFX, FY acting on the dowel 20c in the dowel plane XY. The rig may further comprise a control unit (not visible), which is communicatively connected to the force sensor, and the control unit is arranged to determine the compression force FN acting on the dowel 20c in the normal direction N of the dowel 20c, as well as a first sideway acting force FX, acting on the dowel 20c in an X-direction X, and a second sideway acting force FY, acting on the dowel 20c in an Y-direction Y. The X-direction X, the Y-direction Y and the normal direction N are perpendicular to each other, and he first and second directions X, Y may be upward and sideward directions along relative the feed beam 5, which is as said directions along the dowel plane XY. The compression forces are thus determined based on the forces sensed by the at least one force sensor. By this information, the side forces FX, FY (if any) may be minimized to avoid dowel release and also the actual compression force FN acting on the dowel 20c in the normal direction N may be determined, wherein the correct pressure may be applied to create a correct pressure force during for example the drill operation performed by the rig 50.

[0045] Fig. 4a shows a side view and Fig. 4b shows a top view of the dowel 20c of Fig. 2, according one embodiment of the invention. As may be seen, the dowel 20c is arranged as a pad (preferably made of rubber) with a certain thickness int the normal direction N. The dowel 20c comprises according to this preferred embodiment, a first force sensor 31 , a second force sensor 32 and a third force sensor 33, which each are arranged to sense a force in the normal direction N to the dowel plane XY of the dowel 20c. The force sensors 31 , 32, 33 are in this case one-axial force sensors each arranged to sense forces along their extension, and the force sensors are arranged spaced apart perpendicular to the dowel plane XY of the dowel 20c (i.e. arranged along the normal direction N). By position the force sensors 31 , 32, 33 spaced apart, any angled counter force F, may be sensed and re-calculated (determined) to the compression force FN acting on the dowel 20c in the normal direction N and the first sideway acting force FX, acting on the dowel 20c in the X-direction X, and the second sideway acting force FY, acting on the dowel 20c in the Y-direction Y. Differences in the pressure forces F1 , F2, F3 of the respective sensor 31 , 32, 33 are used to determine the compression force FN and side forces FX, FY acting on the dowel 20c, in the same way as described above.The respective sensor 31 , 32, 33 preferably extends from the pad-like front part of the dowel 20c to a fixation plate 20d (or the like), which is attached to the stinger 20 or the feed beam 5, depending on if the rig 50 comprises the stinger 20 or if the dowel 20c is attached directly to the first end 5a of the feed beam 5.

[0046] Fig. 5a shows a side view and Fig. 5b shows a top view of the dowel 20c, with an alternative embodiment of arranging the force sensors compared to Figs. 4a-b. The dowel 20c comprises according to this preferred embodiment, that the first, second and third force sensors 31 , 32, 33, each are arranged with an angle relative to the normal direction N of the dowel plane XY of the dowel 20c, such that imaginary axes of the force sensors 31 , 32, 33 cross each other at a common intersection point p, which in this case imaginary may be seen as a point at a distance from and in front of the front surface of the dowel 20c. This means, more or less, that the force sensors 31 , 32, 33 are symmetrically arranged around a centre of the pad-like part of the dowel 20c, and are angled outwards, in direction towards a periphery of the fixation plate 20d, in direction away from the front surface of the dowel 20c towards the feed beam 5 (not visible). Also in this embodiment, the force sensors 31 , 32, 33 are one-axial force sensors and by their angled arrangement, they are arranged to sense forces in mutually different directions A, B, C relative each other. The size of the respective force, F1 , in the A-direction, F2 in the B-direction and F3 in the C-direction, together with the angle of the sensors 31 , 32, 33 relative the dowel plane XY (or the normal N) as well as the distance between the sensors 31 , 32, 33 are used to determine the compression force FN and side forces FX, FY acting on the dowel 20c. In Fig. 5a, the sensors are angled outwardly, in direction from the rock engaging surface of the dowel 20c towards the feed beam 5, but it is understood that the first, second and third force sensors 31 , 32, 33 may be angled in the opposite way, i.e. inwardly, wherein the common intersection point p imaginary may be seen as a point at a distance from and behind the front surface of the dowel 20c, at the “feed beam side”.

[0047] Fig. 6a shows a side view and Fig. 6b shows a top view of the dowel 20c, with yet another alternative embodiment of arranging the force sensors comparedto Figs. 4a-b and Figs. 5a-b. The dowel 20c comprises according to this preferred embodiment, that the first, second and third force sensors 31 , 32, 33, each are arranged with an angle relative to the normal direction N of the dowel plane XY of the dowel 20c, such that imaginary axes of the force sensors 31 , 32, 33 cross each other at a common intersection point p, which in this case is arranged at the dowel 20c, which means that they are not spaced apart in the dowel plane XY. This means that the size of the respective force, F1 , in the A-direction, F2 in the B- direction and F3 in the C-direction, together with the angle of the sensors 31 , 32, 33 relative the dowel plane XY (or the normal N) are used to determine the compression force FN and side forces FX, FY acting on the dowel 20c. In the shown embodiment, the first, second and third sensor 31 , 32, 33 are angled outwardly, but it is understood that the first, second and third force sensors 31 , 32, 33 may be angled in the opposite way, i.e. inwardly.

[0048] Fig. 7 shows a flow chart of a method for handling forces acting on a rock engaging dowel 20c of a feed beam 5 of a mining or construction rig 50 according to the invention. The method comprises bringing 101 the rock engaging dowel 20c of the feed beam 5 into contact with a rock face 100, and then sensing 102 forces applied to the dowel 20c in at least in one of the dowel plane XY or in the normal direction N to the dowel plane XY. In the simplest form, only the normal force FN, normal to the dowel plane, or side forces FX, FY, or all three forces FN, FX, FY acting on the dowel 20c are sensed after the contact between the dowel 20c and the rock face 100 is established. After this information is achieved, any action necessary may follow, for example repositioning, apply higher pressure, or just start an operation if the normal counter pressure FN seems high enough and / or if the side forces FX, FY are low.

[0049] The method may further comprise, after the step of sensing 102 forces applied to the dowel 20c, increasing 103 the force applied to the dowel 20c in the normal direction N to the dowel plane XY. This step may be used if the counter pressure in the normal direction FN of the dowel 20c initially is too low compared to a predetermined value, for example if a determined counter pressure of 1 .0 kN is estimated to be enough for a drilling operation, the counter pressure in thenormal direction FN might be determined to 1.1 kN. If the counter pressure in the normal direction FN of the dowel 20c initially is sensed as too low, this step may be needed, before actually evaluating (determining) the actual / real forces applied in the normal direction N and the sideways direction X, Y. The step may be performed by for example adjust the boom 4, the feed beam 5 or the stinger 20, depending on the rig arrangement and the situation.

[0050] The method may further comprise determining 104 a compression force FN acting on the dowel 20c in at least a normal direction N to the dowel plane XY of the dowel 20c, based on the forces applied to the dowel 20c and sensed by the at least one force sensor. For example, if the side forces FX, FY might be overcome by increased normal pressure force FN, which may be sensed and calculated depending on force vector analysis, the normal pressure force FN is increased. The steps bringing 101 , sensing 102, increasing 103 and determining 104 may be iterative, until the counter pressure forces FN, FX, FY are the determined (for example within certain limits).

[0051] The method may further comprise adjusting 110 the direction of the feed beam 5 in relation to the rock face 100, based on the determined compression force FN in the normal direction N to the dowel plane XY of the dowel 20c. Also, this step may be iterative together with the steps of bringing 101 , sensing 102, increasing 103 and determining 104.

[0052] If the feed beam 5 of the rig 50 comprises a stinger 20, the method further may comprise, after the step of determining 104 the compression force FN in the normal direction N to the dowel plane XY of the dowel 20c, extending 105 the stinger 20 for increasing 103 the compression force FN applied to the dowel 20c. This is positive since it is time consuming to rearrange the boom 4 and / or the feed beam 5, wherein increasing the pressure by means of extending (or retracting) the stinger 20 by an actuator, is a fast way of adjusting the pressure.

[0053] Since dowel release is a problem of prior art solutions, the method is directed to solve this in an even deeper lever, wherein the method further may comprise determining 106 a first sideway acting force FX acting on the dowel 20cin an X-direction X and a second sideway acting force FY acting on the dowel 20c in an Y-direction Y, based on the forces applied to the dowel 20c and sensed by the force sensor / sensors. The X-direction X, the Y-direction Y and the normal direction N to the dowel plane XY are perpendicular to each other. When the side forces FX, FY have been determined 106, a step follows of minimizing 107 any determined first and second sideway acting forces FX, FY acting on the dowel 20c by adjusting 111 the orientation of the feed beam 5 in relation to the rock face, based on determined first and / or second sideway acting forces FX, FY. The minimizing 107 of any determined first and second sideway acting forces FX, FY may comprise minimizing 107 until at least one of the first and second sideway acting forces FX, FY is below a first threshold value FI M. The method may also comprise, if any determined first and second sideway acting forces FX, FY are above a second threshold value F2iimit, repeating the method from the beginning (the step of applying 101 the rock engaging dowel 20c to a rock face by the feed beam 5 and / or the stinger 20). As understood, the first threshold value FI M is smaller than second threshold value F2iimit.

[0054] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the abovedescribed embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

CLAIMS1 . A sensor arrangement (1 ), for measuring contact feed force between a rock face (100) of a rock to be drilled and a feed beam (5) of a mining or construction rig (50), the rig (50) comprising:- a boom (4), arranged on the mining or construction rig (50),- the feed beam (5), arranged on the boom (4), and which feed beam (5) is arranged to shuttle an object (40) along a longitudinal axis of the feed beam (5) in a feeding direction (Z) or a direction opposite to the feeding direction (Z),- a rock engaging dowel (20c) for engaging the rock face (100) to stabilize the feed beam (5) during operation of the rig (50), wherein the dowel (20c) is arranged at a first end (5a) of the feed beam (5) and the dowel (20c) has an extension in a dowel plane (XY) with a normal direction (N) to the dowel plane (XY), wherein the sensor arrangement (1 ) comprising:- at least one force sensor, arranged to sense forces applied to the dowel (20c), wherein the at least one force sensor is arranged at the dowel (20c).

2. Sensor arrangement (1 ) according to claim 1 , wherein the at least one force sensor is arranged to sense forces applied to the dowel (20c) at least in one of the normal direction (N) and directions parallel with the dowel plane (XY).

3. Sensor arrangement (1) according to claim 1 or 2, wherein the at least one force sensor is a three-axial force sensor arranged to sense the forces in the directions parallel with the dowel plane (XY) and in the normal direction (Z) to the dowel plane (XY).

4. Sensor arrangement (1) according to claim 1 or 2, wherein the at least one force sensor is a first force sensor (31 ), a second force sensor (32) and a third force sensor (33), wherein the force sensors (31 , 32, 33) are arranged spaced apart in the dowel plane (XY) of the dowel (20c).

5. Sensor arrangement (1) according to claim 4, wherein the first, second and third force sensors (31 , 32, 33) each are arranged to sense a force in the normal direction (N) to the dowel plane (XY) of the dowel (20c).

6. Sensor arrangement (1) according to claim 4, wherein the first, second and third force sensors (31 , 32, 33) are arranged to sense forces in mutually different directions (A, B, C).

7. Sensor arrangement (1) according to claim 6, wherein the first, second and third force sensors (31 , 32, 33) each are arranged with an angle relative to the normal direction (N) of the dowel plane (XY) of the dowel (20c), such that imaginary axes of the first, second and third force sensors (31 , 32, 33) cross each other at a common intersection point (p).

8. Sensor arrangement (1 ) according to claim 7, wherein the common intersection point (p) is arranged at the dowel (20c).

9. Sensor arrangement (1 ) according to any of claims 4 - 8, wherein the first, second and third force sensors (31 , 32, 33) each is a one-axial force sensor.

10. Sensor arrangement (1 ) according to any of the preceding claims, wherein the rig (50) further comprising:- a stinger (20) arranged on the feed beam (5), the stinger (20) comprising a first end (20a) and an opposite second end (20b), wherein the first end (20a) comprises the rock engaging dowel (20c), wherein the stinger (20) extends in a stinger direction from its first end (20a) to its second end (20b), wherein the stinger (20) further comprises a first actuator, arranged for extending and retracting the stinger (20) such that a distance between the first end (20a) and the second end (20b) may be changed.11 . Sensor arrangement (1 ) according to any of the preceding claims, wherein the rig (50) further comprising:- a drill feed (10), arranged for drilling the hole in the rock, and arranged on the feed beam (5).

12. Sensor arrangement (1 ) according to any of the preceding claims, wherein the rig (50) further comprising:- a control unit, communicatively connected to the at least one force sensor, the control unit being arranged to determine a compression force (FN) acting on thedowel (20c) in at least the normal direction (N) of the dowel (20c), based on the forces sensed by the at least one force sensor.

13. Sensor arrangement (1 ) according to claim 12, wherein the control unit further is arranged to determine a first sideway acting force (FX) acting on the dowel (20c) in an X-direction (X) and a second sideway acting force (FY) acting on the dowel (20c) in an Y-direction (Y), wherein the X-direction (X), the Y-direction (Y) and the normal direction (N) are perpendicular to each other.

14. Sensor arrangement (1 ) according to any of claims 12 - 13, wherein the control unit further is arranged to trigger adjustment of direction of the feed beam (5) in relation to the sensed forces.

15. Sensor arrangement (1 ) according to any of claims 10 - 14, wherein the at least one force sensor is fixedly arranged between the first end (20a) of the stinger (20) and the dowel (20c).

16. Method for handling forces acting on a rock engaging dowel (20c) of a feed beam (5) of a mining or construction rig (50) according to any of claims 1-14, the method comprising:- bringing (101 ) the rock engaging dowel (20c) of the feed beam (5) into contact with a rock face (100),- sensing (102) forces applied to the dowel (20c) in at least one of the dowel plane (XY) or the normal direction (N) to the dowel plane (XY).

17. Method according to claim 16, wherein, after the step of sensing (102) forces applied to the dowel (20c), the method further comprising:- increasing (103) the force applied to the dowel (20c) in the normal direction (N) to the dowel plane (XY).

18. Method according to claim 16 or 17, wherein the method further comprising:- determining (104) a compression force (FN) acting on the dowel (20c) in at least a normal direction (N) to the dowel plane (XY) of the dowel (20c), based on the forces applied to the dowel (20c) and sensed by the at least one force sensor.

19. Method according to claim 18, wherein the method further comprising:- adjusting (110) the direction of the feed beam (5) in relation to the rock face, based on the determined compression force (FN) in the normal direction (N) to the dowel plane (XY) of the dowel (20c).

20. Method according to any of claims 18 or 19, when dependent on any of claims 9 - 14, wherein, after the step of determining (104) the compression force (FN) in the normal direction (N) to the dowel plane (XY) of the dowel (20c), the method further comprising:- extending (105) the stinger (20) for increasing (103) the compression force (FN) applied to the dowel (20c).21 . Method according to claim any of claims 16 - 20 when dependent on any of claims 3 - 15, the method further comprising:- determining (106) a first sideway acting force (FX) acting on the dowel (20c) in an X-direction (X) and a second sideway acting force (FY) acting on the dowel (20c) in an Y-direction (Y), wherein the X-direction (X), the Y-direction (Y) and the normal direction (N) to the dowel plane (XY), are perpendicular to each other, based on the forces applied to the dowel (20c) and sensed by the force sensor,- minimizing (107) any determined first and second sideway acting forces (FX, FY) acting on the dowel (20c) by adjusting (111 ) the orientation of the feed beam (5) in relation to the rock face, based on determined first and / or second sideway acting forces (FX, FY).

22. Method according to claim 21 , wherein the minimizing (107) of any determined first and second sideway acting forces (FX, FY) comprises minimizing until at least one of the first and second sideway acting forces (FX, FY) is below a first threshold value (F1 limit).

23. Method according to claim 21 , wherein if any determined first and second sideway acting forces (FX, FY) are above a second threshold value (F2iimit), the method comprises repeating the steps of the method.

24. Method according to claims 22 and 23, wherein the first threshold value (F1 limit) is smaller than second threshold value (F2iimit).

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