Indexing head, bolting unit and method

Abstract

An indexing head, a bolting, head, and a method of providing a rock surface with reinforcing rock bolts. The indexing head (16) is mounted to a front end of a drill feed beam (10) of a drilling unit (5) of a bolting head (4). The indexing head comprises an indexing element (34) provided with a rod clamping tool (36) and a resin feed tool (29). The indexing element can be moved for indexing the rod clamping tool and the resin feed tool selectively on a drilling line (28) .

Description

Background of the invention

[0001] The invention relates to an indexing head for a drilling unit in a rock bolting head and is intended to be utilized when reinforcing rock surfaces.

[0002] The invention further relates to a bolting unit and method.

[0003] The field of the invention is defined more specifically in the preambles of the independent claims.

[0004] In mines, construction sites and at other work areas exists a need to reinforce rock surfaces and to thereby ensure their safety and suitability for the intended purposes. A common method for rock reinforcement is rock bolting. In such reinforcement system several rock bolts are inserted into drilled drill holes and are tensioned. This way rock layers are bonded together so that the risk for collapse is reduced. Prior inserting and tensioning the rock bolt, resin material can be fed into the drilled drill hole for further improving the reinforcement. Typically, the rock bolting is executed by means of a bolting rig comprising a bolting head for drilling the drill holes and for feeding the rock bolts inside the drill holes. The bolting heads comprise indexing devices for moving a drilling unit, a bolting unit and a resin feed means into alignment with the drill holes so that needed reinforcing measures can be executed. However, the present bolting heads have shown to contain some disadvantages.Brief description of the invention

[0005] An object of the invention is to provide a novel and improved indexing head, bolting rig and method for rock reinforcement.

[0006] The indexing head according to the invention is characterized by the characterizing features of a first independent.apparatus claim.

[0007] The bolting rig according to the invention is characterized by the characterizing features of a second independent apparatus claim.

[0008] The method according to the invention is characterized by the charactering features and steps of an independent method claim.

[0009] An idea of the disclosed solution is that a drilling unit of a rock bolting head comprises an indexing head which is capable of executing dual operations, namely handling drill rods and resin feeding. The indexing head is located at a front end part of a drill feed beam of the drilling unit and comprises a rod clamping tool for handling the drill rods by means of a first clamp surface and a second clamp surface. The second clamp surface can be moved by means of a clamping actuator towards the first clamp surface when handling the drill rods. There is also a resin feed tool for feeding resin material into drill holes drilled by means of the drilling unit. The indexing head further comprises an indexing element which is movable by means of at least one indexing actuator in relation to a body of the indexing head. The mentioned first clamp surface of the rod clamping tool and the resin feed tool are both mounted to the indexing element and can be moved together and simultaneously in relation to the body. Thereby, the first clamp surface and the resin feed tool can be indexed selectively to a pre-determined operational position when the indexing actuator is actuated.

[0010] In other words, the indexing head is provided with two tool configurations, the rod clamping tool and the resin feed tool, which can be indexed from their rest positions one at a time to the common operational position. When the shared indexing element is moved, the first clamp surface and the resin feed tool both move simultaneously.

[0011] The operational position is located on a drilling line of a drilling unit when the indexing head is mounted on the drill feed beam. Thus, in this document the operational position means in practice the drilling line. The drilling line is of course in alignment with the drilled drill hole.

[0012] An advantage of the disclosed solution is that moving of the rod clamping tool and the resin feed tool is easy and requires only little space. Further, movement lengths can be short and accurate. The drill feed beam can be kept immovable during the indexing since the indexing movement occurs only in the indexing head. Thus, the drilling line of the drill unit is during the drilling and the resin feed all the time in line with the drill hole.

[0013] According to an embodiment, the indexing head is a separate independent apparatus or unit which is mountable to the drill feed beam. Then the indexing head can be removed and changed when needed and it is also possible to retrofit the indexing head to existing drill feed beams.

[0014] According to an alternative embodiment, the indexing head is constructed to be inseparable part of the drill feed beam.

[0015] According to an embodiment, the second clamp surface of the rod clamping tool is located at the operational position and is movable towards the first clamp surface indexed to the operational position. Then only relatively short movement lengths are needed for the second clamp surface.

[0016] According to an embodiment, the first clamp surface is a first jaw mounted immovably in relation to the indexing element. The second clamp surface is a second jaw and is coupled to the clamping actuator which is located at the operational position. The clamping actuator can move the second jaw towards the first jaw which is indexed to the operational position. Then the first jaw is located opposite to the second jaw.

[0017] In other words, when the clamping actuator is operated, the second jaw can be moved towards the first jaw so that the jaws can grip to the drill rod being on the drilling line i.e., at the operational position. Thereby, movement of the drill rod is prevented and screw-type couplings between extension drill rods can be opened and connected. Thus, the rod clamping tool has gripping capability and a controllable gripping feature.

[0018] According, to an embodiment, the first jaw is at first moved by means of the indexing actuator to the operational position and only thereafter the second jaw is moved towards the first jaw by means of the clamping actuator. Depending on movement length of the second jaw, the jaws can together serve as guiding means or as gripping means for the drill rod. Thus, controlling the clamping actuator, it is possible to select whether the rod clamping device is operating as a guiding device or as a gripper.

[0019] According to an embodiment, the rod clamping tool has two operational features a clamping feature and a guidance feature wherein the operational features are selectable in response to magnitude of movement length of the second clamp surface towards the first clamp surface at the operational position. The clamping actuator is configured to move the second clamp surface a longer distance to press the drill rod being at the operational position against the first clamp surface by means of the second clamp surface for providing the clamping feature and is configured to move the second clamp surface a shorter distance for providing the guidance feature.

[0020] In the guidance feature, the first and second jaws are controlled to be positioned at a short distance from an outer surface of the drill rod located on the drilling line. Then the jaws are not in physical contact with the drill rod and do not prevent rotation and longitudinal movements of the drill rod in relation to the indexing head. However, the jaws which are located close to the drill rod can provide guidance for the drill rod during a drilling phase in case the drill rod is for some reason moving sideways. Thus, the rod clamping tool has guidance capability and a controllable guidance feature.

[0021] According to an embodiment, selection between the clamping feature and the guidance feature can be done by controlling forces of the jaws contacting the outer surface of the drill rod. Thus, the operational features of the rod clamping tool are selectable in response to magnitude of applied force of the second clamp surface towards the first clamp surface at the operational position. Then the clamping actuator can move the second clamp surface with greater force to press against the drill rod and to thereby press the drill rod against the first clamp surface to provide the clamping feature. When the movement of the second clamp surface is done with smaller force then the guidance feature is provided.

[0022] In this embodiment, the guidance feature is provided by pressing the jaws only with limited force against the drill rod so that is still movable, and the drilling can be executed with good guidance.

[0023] According to an embodiment, the first and second jaws may be changeable jaw elements made of wear resistant material, such as hardened steel material. The jaws both comprise contact surfaces with curved shapes corresponding to an outer surface shape of the drill rod. Thus, the jaws may comprise semicircular contact surfaces.

[0024] According to an embodiment, the clamping actuator is a hydraulic cylinder, and the second clamp surface is mounted to a free end of a piston rod of the hydraulic cylinder. Further, the piston rod is oriented towards the operational position, whereby the piston rod can execute linear movement to and from the operational position for moving the second clamp surface to a clamping position and a guiding position in response to movement length of the piston rod. Alternatively, the clamping and guiding features are selected by the force generated by the clamping actuator.

[0025] According to an embodiment, the clamping actuator is a hydraulic cylinder, and it is mounted immovably in relation to the body of the indexing head. Thus, only the piston rod of the cylinder is moved in accordance with the operation of the clamping actuator. Then the disclosed solution may have simple and durable structure.

[0026] According to an alternative embodiment, the clamping actuator may in some applications be mounted also on a moving part and being thereby movable relative to the body of the indexing head.

[0027] According to an embodiment, the clamping actuator may alternatively be a hydraulic or electric motor configured to move the second jaw by means of suitable transmission elements. Further, in some solutions the clamping actuator may also be an electrical linear actuator.

[0028] According to an embodiment, the resin feed tool comprises a feed tube. In other words, the resin material can be fed through a central channel of the feed tube into the drill hole when the resin feed tool is positioned on the drilling line i.e., to the operational position of the indexing head.

[0029] According to an embodiment, resin feed tool is configured to feed resin cartridges into the drill holes. The resin cartridges are filled with one or more resin material, or resin material component, and are covered by means of a cover material. The cartridges can be shot into the drill hole for example by means of pneumatic fluid flow.

[0030] Since a front end of the feed tube is to be placed close to an opening of the drilled hole there is no risk of the cartridges to hit to edges of the drill hole and to be crushed prior being inserted into the drill hole. This way proper feeding of the resin material can be ensured.

[0031] According to an embodiment, resin feed tool is configured to feed bulk form resin material into the drill holes. Then the feed tube is connectable to a supply hose or line through which the bulk type resin material or resin material components can be supplied to the resin feed tool.

[0032] According to an embodiment, the feed tube may be made of rigid material, such as steel.

[0033] According to an embodiment, the resin tube may be a changeable piece which can be changed if being worn or damaged.

[0034] According to an embodiment, the feed tube comprise a first straight section which is parallel with the drilling line, and a second slanted section having angular orientation in relation to the first section. A distal end of the second slanted section may be connected to a feed hose, or corresponding resin material supply line. The second section being oriented angularly sideways provides more space and facilitates the feeding of the resin material to the indexing head.

[0035] According to an embodiment, the resin feed tool may comprise an actuator or a feed device for moving a front end of the feed tube close to an opening of the drill hole. Then the entire feed tube may be moved axially, or alternatively or in addition to, the feed tube be comprise an extendable structure actuated by mean of the actuator. An advantage of this embodiment is that feeding of the resin material to the drill hole is further ensured.

[0036] According to an embodiment the feed tube may be entered by means of the above mentioned actuator partially into the drill hole to a desired point inside the drill hole for feeding the resin material, or it can be inserted up to a bottom of the drill hole.

[0037] According to an embodiment, the indexing actuator is a hydraulic cylinder. An advantage of use of the hydraulic cylinder for moving the indexing element is that the hydraulic cylinders are reliable and inexpensive actuators.

[0038] According to an embodiment, the indexing element is turnable. Then the indexing element together with the rod clamping tool and the resin feed tool can be turned in relation to the body for indexing the rod clamping tool and the resin feed tool simultaneously by means of turning movement generated by the indexing actuator. An advantage, of this solution is that the turning mechanism can be designed to be compact in size and that indexing movements can be relatively short. Thereby operation of the indexing head can be reliable. The structure can also be relatively simple and easy to manufacture.

[0039] According to an embodiment, the indexing element is a cam arranged to be turned around a pivot and in relation to the body by means of the indexing actuator. The cam can be turned by means of a hydraulic cylinder serving as the indexing actuator. Alternatively, the cam can be turned by means of hydraulic motor, or any other suitable hydraulically or electrically operable actuator.

[0040] According to an embodiment, the indexing element together with the rod clamping tool and the resin feed tool are arranged to be linearly movable in relation to the body, whereby the rod clamping tool and the resin feed tool are indexable by means of a linear movement generated by the indexing actuator.

[0041] According to an embodiment, the linearly movable indexing element may be a plate-like piece, a sliding piece, or structure provided with the rod clamping tool and the resin feed tool and being movable along guide surfaces arranged on the body.

[0042] According to an embodiment, the indexing element comprises a thrust surface for pushing a drill rod sideways away from the operational position in response to indexing movement moving the resin feed tool to the operational position. In other words, the trust surface is configured to subject the indexing movement to a distal end portion of the drill rod which is located on the drilling line. This way the drill rod needs not to be pulled backwards on the drill feed beam but instead the front end portion of the drill rod can be bent to side so that sufficient space is provided for moving the resin feed tool to the operational position. The drill rod end gives way to the resin feed tool. An advantage of this drill rod bending feature is that the resin feed tool can be placed to the operational position quickly and without moving the drilling unit or a rock drilling machine. A further advantage is that no separate actuators or pushing devices are needed since the trust surface is arranged to move together with the resin feed tool and utilizes the same indexing actuator.

[0043] According to an embodiment, the disclosed solution relates also to a bolting head for providing a rock surface with reinforcing rock bolts. The bolting head comprises: a frame for supporting the bolting head and being mountable to a boom of a bolting rig; at least one drilling unit for drilling drill holes and comprising a drill feed beam and a rock drilling machine movable on the drill feed beam; at least one bolting unit comprising a bolting feed beam and a bolt feed device for inserting the rock bolts to the drill holes and being movable on the bolting feed beam; resin feed means for feeding resin material to the drilled drill hole; means for handling drill rods mountable to the rock drilling machine; and indexing means for moving the drilling unit and the bolting unit in relation to the frame and for bringing the drilling unit and the bolting unit selectively into an alignment with the drill hole. The bolting head further comprises an indexing head mounted at a distal front end portion of the drill feed beam. The indexing head is in accordance with the features and embodiments disclosed in this document and comprises a rod clamping tool and a resin feed tool both mounted to an indexing element and configured to be indexable by means of at least one indexing actuator selectively to a drilling line.

[0044] An advantage of the disclosed bolting head configuration is that there is no need to move the drilling unit between the drilling and the resin feed measures. Further, when the indexing head has three functions, namely drill rod guidance, drill rod gripping and resin feed, the overall structure of the bolting head may be simpler, compact, reliable, and effective in use.

[0045] According to an embodiment, the bolting head is intended for rock bolting in low profile rock galleries and implements extension rock drilling. Therefore, there is a need for the rod handling tool for handling extension drill rods.

[0046] According to an embodiment, the disclosed solution relates also to a method for providing a rock surface with reinforcing rock bolts. The method comprises: executing a drilling phase comprising drilling drill holes to the rock surface by means of a drilling unit of a bolting head mounted to a rock bolting rig; executing a resin feed phase comprising feeding resin material to the drilled drill holes through a resin feed tool; executing a rock bolt insertion phase comprising inserting rock bolts to the drill holes by means of a bolting unit of the bolting head; keeping a drill feed beam of the drilling unit on the drilling line for the duration of the drilling phase and the resin feed phase; and wherein the drilling phase is executed as an extension drilling and comprises handling of drill rods on a drilling line by means of a rod clamping tool. The method further comprises: implementing a movable indexing element comprising at least one clamp surface of the rod clamping tool and the resin feed tool; moving the indexing element, the clamp surface and the resin feed tool all together by means of a common indexing actuator; and using magnitude of movement length of the indexing element to select which one of the clamp surface and the resin feed tool is positioned on the drilling line.

[0047] According to an embodiment, the method further comprises: providing the indexing element with a first clamp surface and moving a second clamp surface by means of a clamping actuator towards the first clamp surface when the first clamp surface is indexed on the drilling line; clamping the drill rod on the drilling line by pressing the second clamp surface against an outer surface of drill rod whereby the drilling rod is forced against the first clamp surface provided on the indexing element; and providing selectively lateral' guiding for the drill rod on the drilling line by positioning the second clamp surface at a distance from the outer surface of the drill rod, whereby the drill rod is located between the first clamp surface and the second clamp surface without physical contact.

[0048] The above disclosed embodiments may be combined in order to form suitable solutions having those of the above features that are needed.Brief description of the figures

[0049] Some embodiments are described in more detail in the accompanying drawings, in which Figure 1 is a schematic side view of a rock bolting rig provided with a boom and a bolting head, Figure 2 is a schematic diagram showing measures relating to rock reinforcing, Figure 3 is a schematic side view of a bolting head, Figure 4 is a schematic top view of the bolting head disclosed in Figure 3, Figures 5 is a schematic view of a drilling unit of the bolting head, Figures 6 and 7 are schematic views showing an indexing head provided with a turnable indexing element, and Figures 8 and 9 are schematic views showing an indexing head provided with a linearly movable indexing element.

[0050] For the sake of clarity, the figures show some embodiments of the disclosed solution in a simplified manner. In the figures, like reference numerals identify like elements.Detailed description of some embodiments

[0051] Figure 1 discloses a bolting rig 1 comprising a movable carrier 2 and at least one boom 3 mounted on the carrier 2. A bolting head 4 is mounted on the boom 3. The bolting head 4 comprises a drilling unit 5 for drilling drill holes 6 and a bolting unit 7 for inserting rock bolts 8 to the drill holes 6. The drilling unit 5 and the bolting unit 7 are arranged to the bolting head 4 so that they can be indexed. At first the drill hole 6 is drilled by means of the drilling unit 5 comprising a rock drilling machine 9 movable on a drill feed beam 10 and provided with a drill rod 11. When the drilling is completed, resin material can be fed from a resin feed device 12 via resin feed hoses 13 or conduits to the drill hole 6. After the resin feed phase the bolting head 4 is indexed and the bolting unit 7 is moved in alignment with the drill hole 6 so that the rock bolt 8 can be inserted. The bolting unit 7 comprises a bolting feed beam 14 and a bolt feed device 15 movable on the bolting feed beam 14. The bolt feed device can push the rock bolt 8 to the drill hole 6 and can execute pre-tensioning by tightening tensioning screws of the rock bolt 8. Operation and work cycle of the rock bolting rig 1 and its bolting unit 4 can be controlled automatically under control of a control unit CU, or the control can be executed manually or in assistance with the control unit CU.

[0052] Figure 1 further discloses that at a front end of the drill feed beam 10 there is an indexing head 16 which is in accordance with the features disclosed in this document. The indexing head 16 comprises a rod clamping tool for handling drill rods 11 and a resin feed tool which is configured to receive the resin material from the resin feed hose 13. Thus the indexing device 16 is a multifunctional device configured to facilitate the drilling and resin feed measures.

[0053] Figure 2 discloses that rock surface reinforcing 17 comprises a drilling phase 18 which is executed by a drilling unit 5. The drilling may be extension drilling 19 whereby there is not only a need to guide 20 drill rods but also to clamp 21 the drill rods when connecting and uncoupling the drill rods. The drilling unit 5 is also provided with means for executing a resin feed phase 22 for feeding either resin cartridges 23 or bulk type resin 24 into the drilled drill hole. When the drilling phase 18 and the resin feed phase 22 are completed, a rock bolt insertion phase 25 is executed by means of the bolting unit 7 for executing rock bolt feed 26 and tensioning 27 of the rock bolt.

[0054] Figure 3 discloses a bolting head 4 comprising a drilling unit 5, a bolting unit 7, and an indexing head 16 at a front end of a drill feed beam 10. Drilling axis 28 are passing through a rock drilling machine 9 and the indexing head 16. The drilling axis 28 is also called as an operational position of the indexing head 16 wherefore the same reference numeral is used for it. The indexing head 16 comprises a resin feed tool 29 provided with a resin feed tube 30 for receiving feed material and conducting it further to a drill hole on the drilling axis. Rod clamping and guiding means of the indexing head 16 are not visible in Figure 3. There is also a bolt magazine 31 which can store several rock bolts 8. In Figure 3 the magazine 31 is of rotating type but it can alternatively be of linear type. Further, it may also be possible to store extension drill rods to the magazine 31, or alternatively there is another magazine or arrangement for storing the drill rods.

[0055] Figure 4 discloses that the bolting head 4 is provided with indexing means for turning T1 the drilling unit 5 and the bolting unit 7 in relation to a turning joint 32 so that one of the drilling unit 5 and the bolting unit 7 can be moved in alignment with the drill hole.

[0056] Figure 5 shows the drilling unit 5 in one additional view angle. A manipulator 47 or handling arm may be provided for handling drill rods 11 when executing extension drilling.

[0057] Figure 6 shows an indexing head 16 in a clamping position and Figure 7 in a resin feed position.

[0058] The indexing head 16 comprises a body 33 and an indexing element 34 movable by means of an indexing actuator 35 in relation to the body 33. The indexing head 16 further comprises a rod clamping tool 36 for clamping and guiding drill rods 11. The rod clamping tool 36 comprises a first clamp surface 37 and a second clamp surface 38. The second clamp surface 38 is movable by means of a clamping actuator 39 towards the first clamp surface 37. The clamping actuator 39 is a hydraulic cylinder 40. The first clamp surface 37 is mounted to the indexing element 34 and the second clamp surface 38 is mounted to a piston rod 41 of the hydraulic cylinder 40. The clamping actuator 39 is mounted immovably to the body 33 and is located at a pre-determined operation position 28 or drilling line.

[0059] The indexing element 34 is a cam piece turnable T2 around a pivot 42 by means of a hydraulic cylinder 43 serving as the indexing actuator 35. In addition to the first clamp surface 37, which is part of the rod clamping tool 36, the indexing element 34 comprises a resin feed tool 29. The resin feed tool 29 comprises a feed tube 30 which is shown in Figure 6 in a rest position wherein it is not aligned on the operational position 28. Instead, the rod clamping tool 36 is indexed to the operational position 28 wherein the second clamp surface 38 is moved towards the drill rod 11. Depending on movement length of the second clamp surface 38, or magnitude of force generated by the clamping actuator, the rod clamping tool 36 can provide the drill rod 11 lateral guidance or it can grip the drill rod 11. The magnitude of force generated by the clamping actuator can be managed by means of one or more sensors.

[0060] In Figure 7 the hydraulic cylinder 43 serving as the indexing actuator 35 has executed its stroke outwards and has turned the indexing element 34 counterclockwise around the pivot 42. Then the first clamp surface 37 of the rod clamping tool 36 and the resin feed tool 29 are moved together and simultaneously in relation to the body 33. Thus, the first clamp surface 37 and the resin feed tool 29 are indexable by means of the indexing actuator 35 selectively to the operational position 28.

[0061] Stroke management of the hydraulic cylinder 43 can be executed either by reaching each extreme position of the hydraulic piston, or by utilizing specific stoppers that can be adjusted, or by utilizing sensor monitoring for recognizing movement of a piston rod. Other possible control principles can also be implemented.

[0062] The indexing element 34 also comprises a thrust surface 44 for pushing the drill rod 11 away from the operational position 28 when the resin feed tool 29 is indexed to the operational position 28. Then the drill rod 11 is bent by means of the turning movement of the indexing element 34.

[0063] Figure 7 further shows that the first clamp surface 37 may comprise a first jaw 45 and the second clamp surface 38 may comprise a second jaw 46. The jaws 45 and 46 may be changeable pieces and their face surfaces may be shaped to correspond shape of an outer surface of the drill rod 11.

[0064] Figures 8 and 9 discloses an indexing head 16 which differs from the solution disclosed in Figures 6 and 7 in that an indexing element 34 is moved linearly L. Operating principle is the same as in Figures 6 and 7. An indexing actuator 35 which is a hydraulic cylinder 43 is coupled to the indexing element 34 and can execute vertical movement for providing indexing for a rod handling tool 36 and a resin feed tool 29. The indexing element 34 may be a slide piece provided with a first jaw 45 and a feed tube 30. A clamping actuator 39 may be orientated perpendicularly to the linear movement direction L of the indexing element 34 and is arranged to move a second jaw 46.

[0065] In Figure 9 the hydraulic cylinder 43 is retracted and the indexing element 34 is moved downwards. A thrust surface 44 of the indexing element 34 pushes a drill rod 11 away from an operational position 28 and allows the resin feed tube 30 to substitute it. The body 33 may comprise guide surfaces or elements for providing the indexing element 34 guidance for the linear movement L.

[0066] It can be seen that also this linearly moving solution utilizes simple and compact structure. Furthermore, movements of the indexing actuator 35 and the clamping actuator 39 can be short and easy to control.

[0067] The drawings and the related description are only intended to illustrate the idea of the invention. In its details, the invention may vary within the scope of the claims.

Claims

1. An indexing head (16) for a drilling unit (5) in a rock bolting head (4), wherein the indexing head (16) comprises: a body (33) mountable to a front end part of a drill feed beam (10) of the drilling unit (5); a rod clamping tool (36) for handling drill rods (11) connectable to a rock drilling machine (9) of the drilling unit (5) and comprising a first clamp surface (37) and a second clamp surface (38), wherein the second clamp surface (38) is movable by means of a clamping actuator (39) towards the first clamp surface (37); and a resin feed tool (29) for feeding resin material into drill holes (6) drilled by means of the drilling unit (5); characterized in that the indexing head (16) further comprises an indexing element (34) movable by means of at least one indexing actuator (35) in relation to the body (33); the first clamp surface (37) of the rod clamping tool (36) and the resin feed tool (29) are mounted to the indexing element (34) and are movable together and simultaneously in relation to the body (33) whereby the first clamp surface (37) and the resin feed tool (29) are indexable by means of the indexing actuator (35) selectively to a pre-determined operational position (28).

2. The indexing head as claimed in claim 1, characterized in that the second clamp surface (38) is located at the operational position (28) and is movable towards the first clamp surface (37) indexed to the operational position (28).

3. The indexing head as claimed in claim 1 or 2, characterized in that the first clamp surface (37) is a first jaw (45) mounted immovably in relation to the indexing element (34); the second clamp surface (38) is a second jaw (46) coupled to the clamping actuator (39) which is located at the operational position (28); and the clamping actuator (39) is configured to move the second jaw (46) towards the first jaw (45) being indexed to the operational position (28) and being thereby opposite to the second jaw (46) .

4. The indexing head as claimed in any one of the preceding claims 1 - 3, characterized in that the rod clamping tool (36) has two operational features a clamping feature and a guidance feature wherein the operational features are selectable in response to magnitude of movement length of the second clamp surface (38) towards the first clamp surface (37) at the operational position (28); and wherein the clamping actuator (39) is configured to move the second clamp surface (38) a longer distance to press the drill rod (11) being at the operational position (28) against the first clamp surface (37) by means of the second clamp surface (38) for providing the clamping feature and is configured to move the second clamp surface (38) a shorter distance for providing the guidance feature.

5. The indexing head as claimed in any one of the preceding claims 1 - 3, characterized in that the rod clamping tool (36) has two operational features a clamping feature and a guidance feature wherein the operational features are selectable in response to magnitude of applied force of the second clamp surface (38) towards the first clamp surface (37) at the operational position (28); and wherein the clamping actuator (39) is configured to move the second clamp surface (38) with greater force to press the drill rod (11) being at the operational position (28) against the first clamp surface (37) by means of the second clamp surface (38) for providing the clamping feature and is configured to move the second clamp surface (38) with smaller force for providing the guidance feature.

6. The indexing head as claimed in any one of the preceding claims 1 - 5, characterized in that the clamping actuator (39) is a hydraulic cylinder (40) ; the second clamp surface (38) is mounted to a free end of a piston rod (41) of the hydraulic cylinder (40); and the piston rod (41) is oriented towards the operational position (28), whereby the piston rod (41) is configured to execute linear movement to and from the operational position (28) for moving the second clamp surface (38) to a clamping position and a guiding position in response to movement length of the piston rod (41) or force generated by the clamping actuator (39).

7. The indexing head as claimed in claim 6, characterized in that the hydraulic cylinder (40) serving as the clamping actuator (39) is mounted immovably in relation to the body (33) of the indexing head (16) and only the piston rod (41) is movable.

8. The indexing head as claimed in any one of the preceding claims 1 - 7, characterized in that the resin feed tool (29) comprises a feed tube (30).

9. The indexing head as claimed in any one of the preceding claims1 - 8, characterized in that the indexing actuator (35) configured to move the indexing element (34) is a hydraulic cylinder (43).

10. The indexing head as claimed in any one of the preceding claims 1 - 9, characterized in that the indexing element (34) together with the rod clamping tool (36) and the resin feed tool (29) are arranged to be turnable (T2) in relation to the body (33), whereby the rod clamping tool (36) and the resin feed tool (29) are indexable by means of a turning movement generated by the indexing actuator (35).

11. The indexing head as claimed in claim 10, characterized in that the indexing element (34) is a cam arranged to be turned (T2) around a pivot (42) and in relation to the body (33) by means of the indexing actuator (35).

12. The indexing head as claimed in any one of the preceding claims 1 - 9, characterized in that the indexing element (34) together with the rod clamping tool (36) and the resin feed tool (29) are arranged to be linearly movable in relation to the body (33), whereby the rod clamping tool (36) and the resin feed tool (29) are indexable by means of a linear movement (L) generated by the indexing actuator (35).

13. The indexing head as claimed in any one of the preceding claims 1 - 12, characterized in that the indexing element (34) comprises a thrust surface (44) configured to push a drill rod (11) sideways away from the operational position (28) in response to indexing movement moving the resin feed tool (29) to the operational position (28).

14. A bolting head (4) for providing a rock surface with reinforcing rock bolts (8), wherein the bolting head (4) comprises: a frame for supporting the bolting head (4) and being mountable to a boom (3) of a bolting rig (1); at least one drilling unit (5) for drilling drill holes (6) and comprising a drill feed beam (10) and a rock drilling machine (9) movable on the drill feed beam (10); at least one bolting unit (7) comprising a bolting feed beam (14) and a bolt feed device (15) for inserting the rock bolts (8) to the drill holes (6) and being movable on the bolting feed beam (14); resin feed means for feeding resin material to the drilled drill hole (6); means for handling drill rods (11) mountable to the rock drilling machine (9); and indexing means for moving the drilling unit (5) and the bolting unit (7) in relation to the frame and for bringing the drilling unit (5) and the bolting unit (7) selectively into an alignment with the drill hole (6); characterized in that the bolting head (4) further comprises an indexing head (16) mounted at a distal front end portion of the drill feed beam (10); and wherein the indexing head (16) is in accordance with the claims 1 - 13 and comprises a rod clamping tool (36) and a resin feed tool (29) both mounted to an indexing element (34) and configured to be indexable by means of at least one indexing actuator (35) selectively to a drilling line (28).

15. A method for providing a rock surface with reinforcing rock bolts (8), the method comprising: executing a drilling phase (18) comprising drilling drill holes (6) to the rock surface by means of a drilling unit (5) of a bolting head (4) mounted to a rock bolting rig (1); executing a resin feed phase (22) comprising feeding resin material to the drilled drill holes (6) through a resin feed tool (29); executing a rock bolt insertion phase (25) comprising inserting rock bolts (8) to the drill holes (6) by means of a bolting unit (7) of the bolting head (4); keeping a drill feed beam (10) of the drilling unit (5) on the drilling line (28) for the duration of the drilling phase (18) and the resin feed phase (22); and wherein the drilling phase (18) is executed as an extension drilling (19), and comprises handling of drill rods (11) on a drilling line (28) by means of a rod clamping tool (36); characterized by implementing a movable indexing element (34) comprising at least one clamp surface (37) of the rod clamping tool (36) and the resin feed tool (29); moving the indexing element (34), the clamp surface (37) and the resin feed tool (29) all together by means of a common indexing actuator (35); and using magnitude of movement length of the indexing element (35) to select which one of the clamp surface (37) and the resin feed tool (29) is positioned on the drilling line (28).

16. The method as claimed in claim 15, characterized by providing the indexing element (34) with a first clamp surface (37) and moving a second clamp surface (38) by means of a clamping actuator (39) towards the first clamp surface (37) when the first clamp surface (37) is indexed on the drilling line (28); clamping the drill rod (11) on the drilling line (28) by pressing the second clamp surface (38) against an outer surface of drill rod (11) whereby the drill rod (11) is forced against the first clamp surface (37) provided on the indexing element (34); and providing selectively lateral guiding for the drill rod (11) on the drilling line (28) by positioning the second clamp surface (38) at a distance from the outer surface of the drill rod (11), whereby the drill rod (11) is located between the first clamp surface (37) and the second clamp surface (38) without physical contact.

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