GB2128228A - A rock bolt rotating device - Google Patents

Abstract

A bolt rotating device for a rock bolting equipment, said bolt rotating device comprising a feeding beam, a rotating mechanism (7) supported by the feeding beam, a feeding device for displacing the rotating mechanism in the longitudinal direction of the feeding beam, and a chucking tool (9) parallel to the feeding beam and rotated by the rotating mechanism for rotating a bolt. The chucking tool is mounted in the rotating mechanism displaceably in relation thereto in the longitudinal direction of the feeding beam so that the length of the chucking tool is adjustable. The rotating mechanism is provided with shifting means (23, 24) for moving the chucking tool so that the chucking tool is at its minimum length when the rotating mechanism is positioned at the rear end of the feeding beam and, correspondingly, at its maximum length when said mechanism is positioned at the front end of the feeding beam. <IMAGE>

Description

SPECIFICATION Bolt rotating device for a rock bolting equipment The present invention concerns a bolt rotating device for a rock bolting equipment, said device comprising a feeding beam, -a a rotating mechanism supported by the feeding beam,fora rock bolt, - a feeding device for displacing the rotating mechanism in the longitudinal direction ofthefeeding beam, -a chucking tool provided with a grasping head for the bolt head, parallel to the feeding beam and rotated bythe rotating mechanism, for rotating the bolt, and -a a shifting device for axial displacement of the chucking tool.

Rock bolting equipment of this type is used for installing and fixing of bolts into holes drilled into a rockforsolder bolting and anchor bolting so asto mix the solder material and to tension the bolt in order to reinforce the rock in mines and in spaces blasted into rock.

In prior art, similar rock bolting equipments are known in which the bolt rotating device is provided with a chucking tool of a constant length, mounted on the rotating mechanism rotably but axially undisplaceably. The chucking tool is designed to grasp the head of the rock bolt so that the chucking tool rotated by the rotating mechanism turns the bolt around its axis at the same time asthefeeding device displaces the rotating mechanism and the chucking tool along the feeding beam towards the rock in order to push to bolt into the hole drilled into the rock.

When the rocksurface is inclined or broken,the feeding beam does not always extend right onto the rock surface to be bolted. This is why, in prior art rock bolting equipments, the chucking tool has been made long enough so that it reaches about 100 to 150 mm beyond the front end of the feeding beam, directed towardsthe rock, when the feeding device has moved the rotating mechanism to the front end ofthe feeding beam.

The long chucking tool ofthe rotating mechanism, however, increases the overall length of the rotating mechanism and the bolt. In tunnels of low height, itis therefore necessaryto use short bolts, and, since the necessary bolt length for reinforcing the rock is in proportion to the width of the tunnel, in tunnels of low heighttheboltthereby remainstooshort.

It is an object of the present invention to provide a bolt rotating device for rock bolting equipment, which device avoids the above drawbacks and permits a shortening ofthe length ofthe rotating mechanism without loss of the advantage granted by a long chucking tool. This object is achieved by means of a bolt rotating device in accordance with the invention, which is characterized in -thatthe grasping head ofthe chucking tool is displaceable in relation to the rotating mechanism in the longitudinal direction ofthefeeding beam and -that the rotating mechanism is provided with said displacing device for displacing the grasping head of the chucking tool.

The invention is based on the idea thatthe chucking tool is made as of adjustable length, whereby the length ofthe chucking tool can be alternatively shortened and extended so that, when the rotating mechanism is in its backward position, in which the bolt is inserted into the rotating device, the chucking tool is at its minimum length, and, when the rotating mechanism is located at its forward position, in which the bolt is tensioned againstthe rock surface, the chucking tool is at its maximum length.Owing to the fact that, when the bolt is being inserted into the bolt rotating device, the chucking tool has been adjusted to its minimum length, it is possible to use longer bolts than what would be possible in an identical bolt rotating device which is provided with a chucking tool of a constant length and in which the overall length of the rotating mechanism and ofthe bolt when the bolt is inserted in the rotating device is equal. This is of significance in particular in tunnels of low height.

When the chucking tool has been adjusted to its maximum length, it extends beyondthefeeding beam, in the same manner as a tool of a constant length.

The displaceability of the chucking tool can be accomplished simply by pressure fluid operated and/or mechanical actuating members.

The invention will be described in more detail below with reference to the attached drawings, wherein Figures 1 and 2 illustrate a rock drilling equipment provided with a rock bolting equipmentfromtwo different directions, Figures 3,4 and 5 are schematical views of the principle of operation of the bolt rotating device in accordance with the invention in three different operating positions, Figures 6 and 7 are enlarged partial axial sectional views of the rotating mechanism with the chucking tool in two different positions, Figure 8 is a frontviewofthe rotating mechanism, and Figure 9 is a schematical view of the hydraulic circuit ofthe bolt rotating device.

Figures 1 and 2 show a combination of rock drilling equipment and a rock bolting equipment. The rock drilling equipment A comprises a rotary drilling machine 1 and a feeding beam 2. The rock bolting equipment B comprises a bolt rotating device 3, a bolt cassette 4, and a charging device 5. The equipments are supported buy a system of arms not shown, mounted on a trolley or vehicle.

As its main elements, the bolt rotating device 3 comprises a feeding beam 6, a rotating mechanism 7, a feeding device 8, and a chucking-tool 9. The rotating mechanism 7 is mounted on a sledge 10 supported by the feeding beam. The sledge is fixed to a feeding chain driven by a pressure fluid motor 11, which chain displaces the rotating mechanism along the feeding beam from the backward position shown in Fig. 3 to the front position shown in Fig. 5, and back again.

The rotating mechanism 7 comprises a frame 12, to which a pressurefluid motor 13 is attached. The shaft of the motor drives a cogwheel 15 mounted in the frame by means of bearings 14. This cogwheel is in engagement with an external tooth rim 17 provided on a sleeve-shaped rotating shaft 16. The rotating shaft is mounted by means of bearings 18 in the frame so asto be positioned with its centre axis in parallel to the longitudinal axis ofthe feeding beam. Inside the rotating shaft, a hollow spindle 19 belonging to the chucking tool 9 is fitted so thatthe spindle is capable of sliding axially in relation to the rotating shaft but is locked to revolves along with the rotating shaft. The outer end of the spindle forms a grasping end 20, which is provided with a central hole 21 forthe head of the bolt.

The spindle of the chucking tool is connected, by means of a bolt 22 and a thrust bearing 25, to the piston 24 of a pressure fluid cylinder 23 attached to the frame. Between the spindle and the piston there is a little axial play so that the spindle is capable of revolving in relation to the piston but moves axially along with the piston. The pressure fluid connections ofthe cylinder are denoted with the reference numerals 26 and 27. The pressure fluid connections of the motor 13 are denoted with the reference numerals 28 and 29.

Figures 3 to 5 illustrate the operation of the bolt rotating device in accordance with the invention when fixing material cartridges are used for fastening the bolt: Figure 3 shows a situation in which a hole31 has been drilled into the rock 30 forthe rock bolt and cartridges 32 of fixing material have been pushed to the bottom of the hole by means of the charging device 5. The rock bolt 33 has been inserted into the bolt rotating device 3 so that its head is positioned in the hole 21 ofthe chucking key 9, whereupon the device has been brought into line with the hole in the rock. The chucking tool hasthen been pulled by means ofthe piston of the cylinder 23 to a retracted position inside the rotating shaft 16, in which position the axial dimension D of the rotating mechanism 7 is at a minimum.

Figure 4 shows a situation in which the sledge 10 of the rotating mechanism is shifted along the feeding beam 6 bythefeeding device 8, while the motor 13 of the rotating mechanism rotates the chucking tool 9 by means of the rotating shaft 16. Therefore, the bolt is pushed into the hole in the rockwhile revolving, wherebythe revolving bolt crushes and mixes the fixing material cartridges 32.

Figure 5 shows a situation in which the feeding device 8 has displaced the rotating mechanism 7 to the front end ofthefeeding beam and the piston of the cylinder 23 has pushed the spindle of the chucking key 9 outfrom the rotating shaft 16. The chucking key extendsbeyondthefrontendofthefeeding beam and has pushed the bolt and its washer against the rock surface. In this position, the axial dimension D of the rotating mechanism 7 is at a maximum.

For controlling the rotating mechanism in accordancewith the invention, it is possible to use, e.g., a hydraulic system in accordance with Fig. 9. The direction of rotation ofthefeeding device can be controlled by means of a valve 38. When the valve is in the position in accordance with the figure, the shifting motor 11 displaces the rotating mechanism in the feeding direction. The pressure fluid entering via the valve 38 also passes through a pressure-controlled counter-valve 36to a switching counter-valve 35 and furtherto the shifting cylinder 23 of the chucking tool.

Correspondingly, the direction of rotation of the motor 13 of the bolt rotating mechanism is controlled by means of a valve 39, whereby, when the valve is in the position in accordance with the figure, the rotating mechanism rotates the bolt so that it is tightened into its position. The pressure fluid entering through the valve 39 also passes through a resistance countervalve 37 to the pressure-controlled counter-valve 36 and furtherto the cylinder 23 of the bolt chucking tool.

Atthe beginning of the feed, the pressure rises in the line supplied via valve 38 soonerthan in the line supplied via valve 39, whereby the pressure-controlled counter-valve 36 admits onlythe pressure from the valve 38 to the cylinder23 ofthe chucking tool, which pressure keeps the chucking tool at its shortest length.

Beforethe rotating mechanism 7 reaches the front end ofthefeeding beam, it contacts an impulse cylinder 34 attheend ofthefeeding beam, and by means of the piston of the cylinder pushes the pressure liquid of the cylinder out of the cylinder. The pressurefluid is discharged into the same pressure fluid channel as the pressure fluid passing through the valve 39, wherebythe pressure becomes higherthan the pressure of the pressure fluid passing through the valve 38. Therefore the pressure opens one ofthe channels in the valve 36, wherebythe other channel is closed and the pressure fluid attempts to penetrate into the cylinder 23.Since the pressure fluid from the cylinder 23 cannot escape along any other route, its only route of discharge is ontothe same pressurefluid channel along which the pressure fluid passing from the impulse cylinder 34 attempts to penetrate. Therefore the cylinder operates as a differential cylinder in which the effective feeding area is the difference between the areas of the piston, which is the same as the cross-sectional area of the piston rod. Consequently, when the rotating mechanism proceeds towardsthe front end ofthefeeding beam, the chucking tool moves out of the rotating shaft 16. When the rotating mechanism has reached the front end of the feeding beam, the chucking tool has pushed the rock bolt and its washer againstthe rock surface.

When the bolt is being tightened,the impulse valve can no longer be displaced, whereby a part of the pressurefluid passing through the valve 39 to the rotating motor 13 of the bolt rotating mechanism flows through the resistance counter-valve 37 to the cylinder 23 and pushes the chucking tool along with the nut or head of the rockboltwhich is being tightened.

The drawings and the related description are only supposed to illustrate the idea of the invention. In its details, the bolt rotating device according to the invention mayvarywithin the scope of the claims. In stead of a separate shifting cylinder-piston, the spindle of the chucking tool may itself operate as a piston if appropriately shaped.The lengthening of the chuckingtool maytake place by means of a pressure fluid, and the shortening, e.g., by means of a spring or equivalent. The device for displacing the chucking tool may also be mechanical. Likewise, the controlling of the movement ofthe chucking tool may take place in any way whatsoever suitable for the purpose. The chucking tool in accordance with the invention may also be applied to the installation of such bolts in which rotation is not required during the installation.

The axial dimension D ofthe bolt rotating mechanism may be adjusted by means of a pressure fluid or mechanically, and it may be returned to its minimum length, e.g., by means of a spring or equivalent. The pressure fluid coupling orthe mechanical coupling can be arranged so that it is suitableforthe operation in each particular case.

Claims (5)

1. Bolt rotating device for a rock bolting equipment, said device comprising -a feeding beam (6), -a rotating mechanism (7) supported by the feeding beam,fora rock bolt (33), -a a feeding device (8) fordisplacing the rotating mechanism in the longitudinal direction ofthefeeding beam, -a chucking tool (9) provided with a grasping head (20) forthe bolt head, parallel to the feeding beam and rotated by the rotating mechanism, for rotating the bolt, and -a a shifting device (23) for axial displacementofthe chucking tool, characterized in -thatthe grasping head (20) of the chucking tool (9) is displaceable in relation to the rotating mechanism (7) in the longitudinal direction ofthefeeding beam (6) and -thatthe rotating mechanism (7) is provided with said displacing device (23) for displacing the grasping head (20) ofthe chucking tool (9).

2. Device as claimed in claim 1, wherein the rotating mechanism (7) is provided with a sleeveshaped rotating shaft (16), which is in rotating engagementwith a rotating motor (13), characterized in thatthe chucking tool (9) is provided with a spindle (19), which forms the grasping head (20) and which is mounted insidethe rotating shaft (16) and is axially slidably but non-rotably in engagement with the rotating shaft.

3. Device as claimed in claim 2, characterized in thatthe spindle (19) of the chucking tool (9) is connected rotably but axially stationary with the piston (24) of a pressure fluid cylinder (23), which cylinder is mounted stationarily in the rotating mechanism (7).

4. Device as claimed in claim 2, characterized in thatthe spindle (19) ofthe chucking tool (9) operates as the piston of a pressure fluid cylinderstationarily mounted in the rotating mechanism (7) or as the spindle of a mechanical guide screw.

5. Device as claimed in claim 2, characterized in that the spindle (19) ofthe chucking tool (9) is connected rotably but axially stationary to a mechanical shifting mechanism coupled to the rotating mechanism (7).