GB2165287A - Cutting tool for gallery driving machines - Google Patents

Abstract

A cutting tool for a gallery driving machine has a chisel and a chisel holder (2), in which the chisel holder has a coolant nozzle (3) for spraying the chisel and a coolant duct (4) leading to the coolant nozzle. This coolant duct is subdivided into a mounting bore (4a) for the coolant nozzle (3) and a supply bore (4b), which has a substantially larger cross-section than the mounting bore (4a) and is accessible from outside. A coolant filter (5b) inserted into the supply bore (4b) can therefore have a larger filtration area than a filter (5a) in the mounting bore (4a) so that a relatively fine-meshed filter can be used without risk of blockage. This in turn facilitates the use of a coolant nozzle (3) with a relatively narrow cross-section without risk of blockage, so that the chisel (1) can be sprayed and therefore cooled at a reduced coolant escape rate. The restricted coolant escape no longer interferes with operations in the gallery. <IMAGE>

Description

SPECIFICATION Cutting tool for gallery driving machines This invention relates to a cutting tool for gallery driving machines and the like, having a chisel and a chisel holder, in which the chisel holder has at least one coolant nozzle spraying coolant on the chisel and at least one coolant duct, which leads to the coolant nozzle and has at least one mounting bore for the coolant nozzle and a filter upstream of the coolant nozzle, and a supply bore opening into the mounting bore.

When cutting tools are used either for driving galleries or for cutting seams with hard dirt inclusions, relatively high temperatures are reached in the chisels and can give rise to sparking. Spark formation in such conditions can result in explosions if the rock or seam gives off mine gasses. Temperature control is consequently essential. The known method is to spray a coolant, usually water, over the chisels. Since each chisel must be individually cooled, every chisel holder has a coolant nozzle directed onto the chisel. In order to prevent coolant nozzle blockage, the coolant is supplied to the coolant nozzle under extremely high pressure-pressures of several hundred atmospheres are used-on the one hand, while on the other hand the coolant nozzle has a relatively wide cross-section of diameter at least 0.6 mm and usually even more.Experience demonstrated that similar cross-sections in the coolant nozzles in the known cutting tools lead to early blockage. A filter upstream of the coolant nozzle makes no difference, since it can only be designed as a coarse filter because of its small filtration area; otherwise the filter itself would soon become blocked.

Consequently, relatively large volumes of cooling water are consumed in spraying the chisels. This is disadvantageous on several grounds. In the first place, large volumes of escaping water hinder gallery lining operations near the driving face and it is difficult to keep the gallery floor clean because the rock and coal debris is converted as it were into a sludge. The removal of this sludgy debris is a problem in itself. Moreover, there is a risk that the gallery floor will swell up and interfere with the support linings. Finally, the coolant nozzles can often still become blocked, and every blocked coolant nozzle must be replaced. Apart from the time wastage and costs of interrupting the cutting process, it is very easy to lose the affected nozzle. The same applied to the upstream filter. The invention is intended to avoid these disadvantages.

The object of the invention is to provide a cutting tool for gallery driving machines and the like of the type initially described, in which the filtration area is substantially increased without in any way altering the layout, so that on the one hand the risk of filter blockage is substantially lowered and on the other hand the cross-section of the coolant nozzle is substantially reduced without risk of blockage, satisfactory chisel cooling being thereby attainable at a very much lower coolant through-put than hitherto.

According to the present invention, the supply bore has a substantially larger cross-section than the mounting bore and an access bore at the end remote from the coolant supply inlet, which extends to the surface of the chisel holder, through which access bore a filter having a substantially larger filtration area than the filter in the mounting bore can be inserted, and which access bore can be sealed against the escape of coolant.

The invention arises from the recognition that the filtration area can be increased without necessarily widening the mounting bore-which is impossible by reason of the chisel holder layout-so that a larger filter might by accommodated therein, since the supply bore in the chisel holder can be widened without difficulty and a relatively large filter can be inserted into the widened supply bore. This results in a substantial increase in the filtration area. Moreover, since the filtration area has been increased it becomes impossible to insert relatively fine-meshed and hence efficient filters without the risk of premature filter blockage. Furthermore, a fine-meshed and/or fine filters allow the use of a coolant nozzle having a relatively narrow cross-section, which can be reduced under the invention down to a diameter of 0.2 mm.Consequently, the volume of coolant, more specifically water, escaping from the coolant nozzle to spray the chisel is correspondingly small though still quite adequate to maintain satisfactory chisel cooling and hence spark suppression. The diameter of the supply bore is preferably between two and four times, and more particularly preferably three times greater than the diameter of the mounting bore. The same applies to the inserted filter, so that depending on the geological conditions and operating settings it often suffices to use a single filter in the supply bore and dispense with the filter in the mounting bore.This is particularly the case when in accordance with another preferred feature of the invention two supply bores with inserted filters and access bores are disposed on opposite sides of the shank recess in the chisel holder, communicating at one end with the mounting bore for the coolant nozzle and at the other end with the coolant supply inlet. The filtration area in an embodiment having two supply bores is simply doubled, and moreover because of the very much larger cross-section of the filters fitted in the supply bores-compared with a filter in the mounting bore for the coolant nozzle-the filtration area is many times greater. There is an analogous reduction in the risk of filter blockage in use, even if very much finer, i.e., -finer-meshed, filters are used to permit the reduction in coolant nozzle diameter and corresponding coolant escape rate.

Further preferred features of the invention will now be described. Thus, the access bores can be tapped so that one can screw in the filters and threaded plugs which close off the supply bores, optionally with sealing rings interposed. This facilitates the replacement of filters in the supply bores, without the need to remove and risk losing the coolant nozzle. The filters are preferably constructed as filter gauze plugs in threaded jackets which can be screwed in through the access bores. The term filter gauze plugs refers to short tubular gauze filters closed at one end so that the coolant liquid can only escape through the fine-meshed gauze. The threaded plugs are preferably of the Allen screw type, i.e., screws with an internal hexagon, so that they can be screwed home in the chisel holder without protruding.

The advantages accuring from the invention are to be seen substantially in that it provides a cutting tool for gallery driving machines and the like, in which without altering the layout in any way the filtration area of the coolant fil ters upstream of the coolant nozzle is sub stantially increased. This increase in filtration area facilitates the use of particularly efficient and fine-meshed filters without risk of prema ture blockage. This again facilitates the use of a coolant nozzle of extremely narrow cross section down to a diameter of 0.2 mm in the chisel holder without risk of blockage, so that the escape rate of the coolant, more particu larly water, is substantially reduced yet satis factorily chisel cooling is maintained. The re duction in the coolant escape rate eliminates the obstruction of lining operations at the driv ing face.Moreover, there is no longer any problem in keeping the gallery floor clean. The gallery floor is no longer in danger of swelling up and hence damaging the support lining.

Finally, there is no longer any rock and coal sludge, or rather the remaining sludge can be removed without difficulty, while it is no lon ger necessary to replace coolant nozzles so that they cannot get lost. Filter replacements in the supply bores are no problem.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is an axial secton through the chi sel holder in a cutting tool of the invention; Figure 2 is a plan view of the chisel holder of Fig. 1; Figure 3 is a side elevation of the chisel holder with a cutting tool in place; Figure 4 shows the ringed area of Fig. 1, fitted with a coolant nozzle and on a larger scale; and Figure 5 shows the ringed area of Fig. 2 with a filter in place and on a larger scale.

The Figures show a cutting tool for gallery driving machines and the like having a chisel 1 and a chisel holder 2, in which the chisel holder 2 has at least one coolant nozzle 3 spraying coolant on the chisel 1 and at least one coolant duct 4, which leads to the coolant nozzle 3 and has at least one mounting bore 4a for the coolant nozzle 3 and a filter 5a upstream of the coolant nozzle 3, and a supply bore 4b opening into the mounting bore 4a. The supply bore 4b has a substantially larger cross-section than the mounting bore 4a and an access bore 7 at the end remote from the coolant supply inlet 6. Through the access bore 7, a filter 5b having a substantially larger filtration area than the filter 5a in the mounting bore 4a can be inserted into the supply bore 4b.The diameter of the supply bore 4b is between two and four times, and more particularly preferably three times greater than the diameter of the mounting bore 4a. For example, the diameter of the mounting bore 4a can be 4 mm, while that of the supply bore 4b can be 10 or 15 mm. In fact two supply bores 4b with inserted filters 5b and access bores 7 are disposed on opposite sides of the shank recess 8 in the chisel holder 2, communicating at one end with the mounting bore 4a for the coolant nozzle 3 and at the other end with the coolant supply inlet 6. The mounting bore 4a with the coolant nozzle- 3 is disposed at it were on the face of the chisel holder 2 and directed at a prescribed angle towards the chisel 1. The supply bores 4b are connected by ducts 9 to the mounting bore 4a and run substantially orthogonally to the shank recess 8 and the mounting bore 4a, if one ignores their setting angle.

The access bores 7 have an internal thread into which the filters 5b can be screwed, together with threaded plugs 10 which close off the supply bores 4b, optionally with sealing rings interposed in the access bores 7, which are thereby sealed against the escape of coolant, even at the high working pressures in use. The filters 5a, 5b are constructed as filter gauze plugs with threaded jackets 11. The plugs are short tubular gauze filters 12, closed at one end so that the coolant must pass through them. The threaded plugs 10 are constituted by Allen screws countersunk to the access bores 7.

Claims (7)

1. A cutting tool for gallery driving machines and the like, having a chisel and a chisel holder, in which the chisel holder has at least one coolant nozzle spraying coolant on the chisel and at least one coolant duct, which leads to the coolant nozzle and a filter upstream of the coolant nozzle, and a supply bore opening into the mounting bore, and wherein the supply bore has a substantially larger cross-section than the mouunting bore and an access bore at the end remote from the coolant supply inlet, which extends to the surface of the chisel holder, through which access bore a filter having a substantially larger filtration area than the filter in the mounting bore can be inserted into the supply bore, and which access bore can be sealed against the escape of coolant.

2. A cutting tool as in Claim 1, wherein the diameter of the supply bore is between two and four times, and preferably three times greater than the diameter of the mounting bore.

3. A cutting tool as in Claim 1 or Claim 2, wherein two supply bores with inserted filters and acess bores are disposed on opposite sides of the shank recess in the chisel holder, communicating at one end with the mounting bore for the coolant nozzle and at the other end with the coolant supply inlet.

4. A cutting tool as in Claim 3, wherein the access bores are tapped so that one can screw in the filters and threaded plugs which close off the supply bores, optionally with sealing rings interposed.

5. A cutting tool as in Claim 4, wherein the filters are constructed as filter gauze plugs with threaded jackets.

6. A cutting tool as in Claim 4, wherein the threaded plugs are of the Allen screw type.

7. A cutting tool for gallery driving machines and the like substantially as hereinbefore described and with reference to the accompanying drawings.