GB2077325A - Mining unit - Google Patents

Abstract

The mining unit for coal mining combines, according to the invention, has a frontal disc which is cup-shaped and its longitudinal section consists of a flat ring (13) on the periphery and an arcuate area (25) narrowing towards a hub (1) in the direction towards the rear edge of the unit. The disclosed invention can be applied especially for mining of a wet coal bed in coal mines. <IMAGE>

Description

SPECIFICATION Mining unit The present invention relates to a mining unit for a mining coal combine, comprising a hub for mounting the unit on the transmission shaft of the cbmbine, on which there are at least two coaxially arranged screw flights whose outer edges are provided with coal mining cutters, and having a frontal disc with cutters fixed on its perimeter.

The mining unit known from the Polish Patent No. 56,286 has screw flights arranged on a cylindrical hub, said panels being armed with mining cutters on its perimeter. Thus, the mining unit has, in principle, the outline of a cylinder.

From the side facing the coal being mined it is provided with a frontal disc having a circular profile and provided with mining cutters on its perimeter. in the frontal disc it has cut-outs connecting the space in front of said disc with spaces between the screw flights. Through the cut-outs the winning from in front of the frontal disc passes to spaces between the screw flights and is transported by the flights along the axis of the mining unit towards the body of the combine wherein it is poured onto a longwall conveyor.

The mining unit known from the German Patent Specification No. 1,349,873 is a worm-type unit.

It has a frontal plate in the form of a cone whose base is directed towards the body of coal. On the periphery of the conical base of the frontal plate mining cutters are arranged. Screw flights which are also armed on their periphery with mining cutters, are spread along the whole hub of the unit only to the conical surface of the frontal plate.

Thus, the interior of the frontal plate, as seen from the front i.e. the nearer side of the body of coal and looking towards the combine, is hollow, and during mining it is filled with crushed coal.

The mining unit known from Polish Patent Specification No. 93,244 has, iike the unit known from the cited German Patent Specification No.

1,349,873, a hub with screw flights on it.

Moreover, it has frontal panels arranged between screw flights. The frontal panels form a circular profile on the perimeter, whereas along the axis of the unit they form a conical surface directed with its base end (the larger diameter end) towards the body of coal. The peripheries of the frontal panel and screw flights are provided with mining cutters. The screw flights do not partition completely the section of the space between adjacent screw flights but they leave free a part of said section closer to the axis of rotation of the unit. This achieves communication between the interior of the cone formed of frontal panels and the spaces between the screw flights, and in this way the winning from the face of the unit arrives between the screw flights.The flights reach as far as the front of the unit, in other words they penetrate the conical frontal plate, which is conducive to transporting of the winning from the front of the unit to behind the conical plate and then towards the longwall conveyor.

The drawback of the mining unit according to Polish Patent No. 56,285 resides in the high frictional resistances of the mining unit against the body of coal, which is caused by the flat frontal plate. Besides, lumps of mined coal get in between the body of coal and the frontal plate, which increases frictional resistance by the operation of crushing the coal lumps. Although the frontal plate has holes or recesses through which the winning passes to arrive between transporting flights of the unit, the dimensions of these holes are too small to remove the winning effectively from in front of the frontal plate. Increasing the size of said holes is impossible over their determined area, since this would cause weakening of the structure of the mining unit.

The mining unit according to the German Patent No. 1,349,873 does not rub its frontal plate against the body of coal, due to the conical form of said plate. However, during mining, the interior of the cone is filled with lumps of coal, which as a result of the rotary motion of the unit and rubbing of the winning are crushed to small pieces. This drawback is caused by a lack of holes in the frontal conical plate, through which the winning could pass to arrive between the screw flights to be transported onto a longwall conveyor.

The above mentioned drawbacks are not present in the mining unit known from Polish Patent No. 93,244; nevertheless, its operation shows an imperfection resulting from a rather small space between flights, as said space is reduced in the front part of the unit by the conical frontal plate penetrating said space. In the region where the screw flights meet the surface of the conical frontal plate a small space is formed between a flight into which space two streams of winning fall. One stream is that of the coal mined by the cutters arranged on the outer edges of the flights; the other stream of the winning comes from the space from in front of the frontal plate through holes in said plate in between the flights.

This hinders the transport of coal towards the longwall conveyor and results in crushing the winning into excessively small lumps.

Transporting the coal away from these diminished spaces is performed so ineffecfively that after a certain time of operation of the unit, especially in wet coal, the winning is totally immobilized by clogging of said space. Efficiency of operation of the mining unit is subject to further and considerable change for the worse.

The object of the present invention is to avoid the drawbacks discussed in the presentation of the known solutions.

Accordingly, the present invention provides a mining unit for a coal mining combine, comprising a hub for mounting the unit on the transmission shaft of the combine, at least two co-axially arranged screw flights on the hub and provided on their outer edges with cutters, the hub including a frontal disc with cutters on its perimeter, wherein the frontal disc has a cup-shaped longitudinal section, and consists of a flat ring at the rim of the cup periphery and an arcuate region behind the rim narrowing towards the hub in the rearward direction along the mining unit.The cup-shape of the frontal disc is achieved due to the fact that the disc is made of panels attached between screw flights and bent backwards arcuately with the convexity directed to the axis of rotation of the unit, whereby particular panels of the frontal plate are attached to one of the screw panels only on its part, so that from the side of the hub an opening is left which connects the space between screw flights and the interior of the cup-shaped frontal disc.

The invention is shown by way of example with reference to the accompanying drawings in which FIGURE 1 is the view of the unit from the side of the frontal plate; FIGURE 2 is a sectional view of the unit taken on section line A-A in Figure 1; FIGURE 3 is a perspective view of the unit seen in the direction shown by the arrow W of Figure 1; FIGURE 4 is a schematic illustration of a longitudinal sectional view (i.e. taken on a longitudinal plane passing through the axis of rotation of the unit); FIGURE 5 is a perspective view of a form of the unit having panels of the frontal plate which do not reach the hub; FIGURE 6 is a longitudinal section through the unit shown in Figure 5; and FIGURE 7 is a longitudinal section of a form of the unit having an inverted cup-shaped frontal plate.

The mining unit has a hub 1 directed with its front end 19 towards the body of coal 20 being mined. On the hub 1 are helical flights 2 which are spread over the whole length of the hub 1. In one embodiment of the invention the unit has three helical flights 2 whose front edges 1 5 reach the frant base 19 of the hub 1. The outer edges 21 of helical flights 2 form a cylindrical profile of the unit and are armed with cutters 22 fixed in holders 23 which are coupled to the flights 2 by means of, for example, welds. The drawing shows only one holder 23 and one cutter 22 on a helical flight 2 but there is in fact a bigger number of cutters 22 on each helical flight 2. The flights are directed in accordance with the direction of working rotation of the mining unit.

The frontal disc 3 is divided by the helical flights 2 into parts 3a situated between flights 2 so that the number of parts 3a of the frontal disc 3 corresponds to the number of flights 2. A part 3a is formed of a fragment of a flat ring 1 3 which forms a circular edge 12. The holders 23 are attached to the ring 13 and have the cutters 22 fixed thereto. Figures 1 and 2 show one of many holders 23 and its cutter 22 on a flight 2. The holders 23 are mounted so that particular cutters 22 are inclined in relation to one another, due to which they cut out in the body of coal a groove wider than the width of the edge 12 (Figure 5). A part 3a has an area 25 or 25a having a radius of curvature R and directed with the convexity inwards towards the hub 1 of the unit.The ring 1 3 and area 25, 25a form an integral whole, and the ring 13 is tangent to the area 25 or 25a. The part 3a is fixed to the slight 2 along its whole inner edge 11 (Figure 3) on the side of the flight 2, which is opposite to the direction of rotation of the unit. To the neighbouring flight 2 the part 3a is fixed on the side of the flight 2 turned in the direction of rotation of the unit. The part 3a is connected to the flight 2 along the edge 6 only in the upper part in the region of the ring 13 and in a part of the area 25 or 25a because a part of the area 25 or 25a is cut away to leave an opening 10 which is limited by an edge 9 passing in the space 8 between flights 2. Through openings 10 mined coal from the interior of the frontal disc 3 gets into the space 8 between flights 2. Parts 3a of the frontal disc 3 are limited by an edge 5 from the side of the combine.The edge 5 meets the hub 1 when the area 25a is provided or is situated above the hub 1, if the part 3a has the area 25. The latter solution is applied in working units having larger outer diameters. The mining unit can be complete with scrapers 4 situated inside the frontal disc 3 and connected with the hub 1 along the edge 16, with the part 3a along the edge 17, and with the flight 2 along the edge 1 5. The scrapers 4 are situated so that they do not cover up openings 10 and are inclined towards the openings 10 so that from the side of flights 2 they are fixed in the region of the edge 1 5. In mining units designed for especially brittle coals, the parts 3A are bent with a radius R and turned with the convexity in the direction of the axis of rotation of the unit. In this embodiment the hub 1 reaches only the edge 5 of the part 3a, as shown in Figure 7.Due to this an enlarged space for crushed winning is formed at the front of the mining unit.

The mining unit is set in rotary motion, and at the same time it advances along the heading together with the combine. In arm-type combines the mining unit can perform movements transverse in relation to the floor; however, these transverse movements are not, in principle, working movements but only movements serving for setting the unit at an appropriate height depending on the height of the coal bed. The rotary and translatory motions of the working unit cause the cutters 22 t6 cut into the body of coal 20 and to break off the coal therefrom. Coal mined by those cutters 22 situated on edges 21 of the flights 2 falls down to the space 8 and is transported away therefrom in the direction of a longwall conveyor due to the helical arrangement of the flights 2.

Coal mined by the cutters 22 arranged on the edge 12 of the frontal plate 3 also falls into the space 8, such that the direction of falling is that of the coal mined by cutters 22 deflected towards the spaces 8. On the other hand, the coal mined by those cutters 22 fixed on the edge 12, but deflected towards the body of coal 20, falls into the space between the body of coal 20 and the frontal disc 3. In this space the winning is displaced by scrapers 4 towards the openings 10 through which it gets to the space 8 between flights 2 and is transported onto a longwall conveyor.

Claims (8)

1. A mining unit for coal mining combine, comprising a hub for mounting the unit on the transmission shaft of the combine, at least two coaxially arranged screw flights on the hub and provided on their outer edges with cutters, the hub including a frontal disc with cutters on its perimeter, wherein the frontal disc has a cupshaped longitudinal section, and consists of a flat ring at the rim of the cup periphery and an arcuate region behind the rim narrowing towards the hub in the rearward direction along the mining unit.

2. A mining unit according to claim 1, wherein the frontal disc consists of a number of parts equal to the number of screw flights whereby one such part partially covers a space between two adjacent flights and partially forms an opening connecting the region behind the frontal disc with the said space between the screw flights.

3. A mining unit according to claim 2, wherein the said parts of the frontal disc are fixed to the screw flights along side edges, and from their side nearer the rear edge of the mining unit they leave a free space above the hub along a skew edge.

4. A mining unit according to claim 2, wherein said parts of the frontal disc have side edges fixed to the screw flights and another edge fixed to the hub.

5. A mining unit according to claim 3 or 4, including scrapers extending from the front of the mining unit, which are fixed between an associated hub and screw flight and to the associated said part of the frontal disc.

6. A mining unit according to claim 2 or 3, wherein the arcuate area of the said part of the frontal disc has its concave side facing radially inwardly towards the hub, and is connected to the hub along an edge of the said part.

7. A mining unit according to any one of the preceding claims wherein the said arcuate region of the longitudinal cross-section of the frontal disc has a constant radius of curvature.

8. A mining unit constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, Figures 1 to 4, or Figures 5 and 6, or Figure 7 of the accompanying drawings.