Patent Application
20150308192
The present invention relates to a tensioning device for a chain transmission for movement transfer between a driver device and a slide to be driven by a drive chain along a linear guide of a rock drill rig. The invention also relates to a method for tensioning a chain transmission, a handing device for handling drill string components in a rock drill rig and a rock drill rig.
In a previously known rock drill rig, the rock drilling machine is fastened to a slide being movable to and fro on a feed beam. The transfer of movement from a drive motor to the slide is over a chain transmission which is fastened to the slide.
Because of wear, the drive chain will experience a successive elongation during operation which is the reason for proposals of different arrangements for tensioning the drive chain. Hereby pressing means are previously known that press laterally against a part of the chain with a certain force in order to absorb slack in the drive chain. Another previously known chain tensioning mechanism is comprised of a displacement device for a wheel being arranged in the chain transmission.
An aim of the present invention is to provide a tensioning device as indicated above which comprises a secure and economic further development of tensioning devices for a drive chain in a rock drill rig.
This aim is obtained through the invention in tensioning device as above through a first fastening member for fastening a first end of the drive chain on the slide, and a second fastening member for fastening a second end of the drive chain on a tensioning head which is arranged displaceable in a tension direction of the drive chain on the slide, wherein a spring device is arranged between the tensioning head and the slide for spring loading the tensioning head in the tension direction, and wherein at least one of said first and second fastening members includes adjustment means for adjusting tension in the drive chain.
Hereby it is made possible to provide a desired tension in the chain with simple measures through the combination of said spring device and adjustment device. When these elements are arranged on the slide itself, no particular specialized measures have to be taken that influence the path of the drive chain or the chain transmission itself. The slide can be constructed such that the related elements can be made easy to inspect, adjust and, when required, maintain.
It is preferred that the tensioning head moves on a slide guide being oriented in said tension direction. It is preferred in particular that the slide guide includes two parallel slide rods which pass through bushings being received in the tensioning head.
For i.a. space saving and guiding reasons it is suitable that the spring device includes a pressure spring package arranged around each slide rod. Also other resilient elements are, however, possible to use. Preferably a movement limiter is arranged between the tensioning head and the slide for preventing excessive compression of the spring device.
In a preferred variant of the invention an indirect chain tension sensor is arranged to sense a relative position between the slide and the tensioning head. Through this arrangement a device is realized which in a simple way can verify the presence of adequate drive chain tension.
The indirect chain tension sensor is suitably a sensor from the group: an inductive sensor, a capacitive sensor, a mechanical sensor, a Hall sensor, an optical sensor.
It is preferred that the chain tension sensor is positioned on the slide and that a detectable element intended for detection is positioned on the tensioning head. The reverse positioning is, however, also possible.
According to a preferred aspect of the invention a safety brake is fastened on the slide. This safety brake is in case of chain tension below a determined level arranged to brake the slide through braking engagement with a brake surface extending along the linear guide at for example detected chain tension below a determined level.
It is not excluded that it is possible also to detect a speed of movement of the slide in respect of the linear guide and that a detected speed above a certain level initiate braking of the slide. This can be valuable for increasing safety in case of intact drive chain but failing chain motor or the like.
All together this aspect results in enhanced security for an operator and for other persons in the vicinity of the rig, since the risk of gripping device and drill string components falling are at least considerably reduced.
It is preferred that the security brake is a hydro-mechanical, normally locked clamping brake and that the brake surface is arranged on an elongated brake beam which is arranged adjacent to the linear guide. Hereby the safety brake can be made active at the absence of pressure in a control conduit, resulting in safety, since the brake does not have to be actively controlled for braking.
It shall be noted that tensioning the drive chain is performed in a main direction of the drive chain in the region of the slide, said direction being “tension direction S”. This main direction is parallel to a movement direction of the slide.
In an inventive method for tensioning a chain transmission for movement transfer between a driver device and a slide to be driven by a drive chain along a linear guide of a rock drill rig, a first end of the drive chain is fastened to the slide through a first fastening member, and a second end of the drive chain is fastened through a second fastening member on a tensioning head which is displaced in a tension direction of the drive chain on the slide, wherein the tensioning head is spring loaded in the tension direction through a spring device being arranged between the tensioning head and the slide, and wherein tension in the drive chain is adjusted through adjustment means being included in at least one of said first and second fastening members.
Method features corresponding to the above device features related to variants of the tensioning device are applicable also in respect of variants of the inventive method.
An inventive handling device for handling drill string components in a rock drill rig, wherein the handling device exhibits a linear guide with a slide being displaceable by a chain transmission and a gripping device for drill string components being positioned on the slide is distinguished in that the handling device includes a tensioning device according to the above.
An inventive rock drill rig including a linear guide in the form of a feed beam with a slide being displaceable by a chain transmission and a rock drilling machine being positioned on the slide is distinguished in that the rock drill rig includes a tensioning device according to the above.
The invention will now be described in greater detail by way of embodiments and with reference to the drawings.
The drawings show:
The device for handling drill string components 5 is arranged to handle drill string components being stored in a magazine (not shown) for drill string components close to the rock drill rig and to successively position them in a drill string position of the rock drilling machine 4. The device for handling drill string components 5 is also arranged to successively remove drill string components from the drill string position and place them in said magazine when the drill string is taken out from a bore hole, for example when it is time to replace the drill bit.
In
The device 5 for handling drill string components is attached to the feed beam of a rock drill rig over the first fastening device 13 and a second fastening device 14. The linear guide 6 with supported slide 7 is pivotal in respect of the fastening devices 13 and 14 and to the feed beam by a third rotator 15 around a third rotational axis V3.
The slide 7 is further equipped with a safety brake 16 which co-operates with a brake beam 17 being arranged along the linear guide 6 and being provided with a brake surface on each side. The safety brake 16 is in the shown example a normally locked clamping brake which in unloaded condition clamps on the brake beam 17 such that the slide 7 with associated gripping device 8 is locked in respect of the linear guide for preventing that the slide with the gripping device, possibly with gripped, heavy drill string component, falls to a lowermost position, whereby serious risks for injury on the operator and possible other persons in the vicinity could occur.
The slide also has other means for co-operation with a drive chain, which is indicated with interrupted lines at 18.
This drive chain is driven by a driver device 19 partly being shown in
39 indicates stop lugs for an end position of the slide 7 on the linear guide 6.
In
The first fastening member 24 is in the shown embodiment rigidly fastened to the slide 7 whereas the second fastening member 25 co-operates with the slide 7 over a tensioning arrangement which will be described in the following.
Said second fastening member 25 is most distally provided with engagement means 40 for said drive chain 18. The second fastening member 25 is movable in a tension direction S in respect of the slide 7 which provides a guide 49 allowing a movement in said direction S. On a proximal end, turned inwardly towards the slide 7, the second fastening member is provided with a rod 50, which passes through a movable tensioning head 26.
The tensioning head 26 is movable, likewise in said direction S in respect of the slide 7, through the co-operation of not shown bushings being received in the tensioning head, with a slide guide 29 in the form of two parallel sliding rods 30. The rod 50 protrudes with its proximal end at an opposite end of the tensioning head 26 in respect of the engagement means 40 of the second fastening member 25 and is in this area threaded for the co-operation with one adjustment nut 51 (or more adjustment nuts 51) in order together to form adjustment means 28 for manual adjustment of the tension in the drive chain 18.
The tensioning head 26 is further spring preloaded in a direction in parallel to said tension direction S by way of a spring device 27 being comprised of a two pressure spring packages 31. Each pressure spring package includes in the shown embodiments a pressure spring (only one shown on
Around each pressure spring, which is formed of a cylindrical helix-shaped spring, there is arranged a surrounding sleeve 34 (only one is shown in
35 indicates an indirect chain tension sensor which is rigidly connected to the slide 7 whereas 36 indicates a detectable element being firmly connected to the tensioning head 26.
In case of wear in the chain resulting in chain elongation, the tensioning head 26 will be displaced in said tension direction S in respect of the slide 7, whereby the chain tension sensor 35 will be able to sense absence of proximity to the detectable element 36. Hereby a signal can be emitted over a circuit being connected to the chain tension sensor 35 said circuit and preferably being part of the control system of the rock drill rig.
The signal can be a light or a sound signal or be an electrical signal to a control circuit or the like. The signal can also advantageously be combined with a signal for interruption of hydraulic fluid supply to the above mentioned security brake 16 so as thereby to initiate clamping of the clamping blocks 21 against the brake beam 17 shown in
The same will occur in case of chain breakage, i.e. that the chain tension sensor 35 indicates absence of proximity to the detectable element 36, whereby a warning signal respectively locking of the slide 7 in respect of the linear guide 6 and the brake beam 17 will be initiated.
On
After action of the safety brake, the cause is controlled. Is the reason only insufficient chain tension in spite of faultless drive chain quality, it is normally sufficient to tension the chain. Is the reason that the drive chain is too worn or that it is broken, it has to be replaced.
The invention can be modified within the scope of the following claims. It can thus be arranged that the second fastening member 25 is rigidly connected to the tensioning head 26 whereas the first fastening member includes adjustment means corresponding to the adjustment means 28 on
The adjustment means 28 for manual adjustment of tension in the drive chain 18 can be replaced with motorized adjustment means for adjusting the tension in the drive chain 18. Such motorized adjustment means can be controlled with the aid of signals from an operator but also be automatic and be controlled by signals from a chain tension sensor.
The invention is applicable for a handling device according to the above and also for a chain transmission of a slide for a rock drilling machine in respect of a feed beam of the rock drilling machine.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1251486-5 | Dec 2012 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2013/051583 | 12/20/2013 | WO | 00 |
