GB2205338A

GB2205338A - Reducing ignition risk with a gallery driving machine

Info

Publication number: GB2205338A
Application number: GB08810693A
Authority: GB
Inventors: Friedrich Wilhelm Paurat; Roland Paurat
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-05-22
Filing date: 1988-05-06
Publication date: 1988-12-07
Anticipated expiration: 2008-05-06
Also published as: GB2205338B; DE3717188A1; GB8810693D0; DE3717188C2

Description

24205338 RE.DUCIIIG IGUITION RISK WITH A GALLERY DRIVING 11ACHINE This

invention relates to a method for reducing the ignition risk when operating a gallery driving machine having at least one cutting head arrayed with cutting toolst whereby water from nozzles mounted in fixed positions on the machines, some distance f rom the cutting head#, is f inely atomised and the jets of spray mist issuing from the nozzles are directed on to the cutting head.

In the known method (DE-PS 35 41 886) a water/air mixture is atomised into a uniform spray mist with a droplet size range between 1 and 100pm diameter and issued at a rate deter-mined by the number of cutting toolst viz.r at a water " 0. 2 - spray ra-'l-e of k_o 0.5 1/min per cutting tool in contact with the cutting face and an qir supply rate of 0.2 'to th e 1.51 ri3/r,,in per cutting tool, and the velocity o., water/air mixture issuing from the nozzles is 25 to 30 m/sec at the mouth. This has proved effective. It is based on the 1knowledge khaL-. the atomisation of water by air produces a spray s.,,hich is sucked in by the rotation of the cullittingt.

-ing head. Two effects are produced. Firs.1C.Ly the cutt tracks are cooled and the cutting tools also undergo cooling. In addition, an anti-ignition climate is produced in the working area of the cutting head. The jets-of spray mist can even penetrate into the cutting tracks.

Lhe prior art also discloses (GB-PS 21 04 573) the direction of spray mist jets on to the rock face and cutting tracks. For this purpose,, the cutting head comprises fixed discs which carry the nozzles and do not rotater and rotating discs on which the cutting tools are arrayed.It is further known (DE-PS 19 35 886j, and German periodical "GluckaufForschungsheften. 1980p pages 17 to 21) to use rotating nozzles. Although this ensures some cutting track cooling, it cannot generate or maintain an anti-ignition climate around the entire cutting head.

The object of the invention is to improve the method initially described in respect of the cooling action on the cutting tracks and tools and the simultaneous anti-ignition effect around the operating cutting head.

According to the present invention, for each cutting tool there are injected a water volume of 0.2 to 0.5 1/min and an air volume of 0.2 to 1 M3/m in, under conditions whereby the droplet size range in the mist jets is held between 1 and 100pm, the air velocity in the nozzles being so adjusted and the nozzles- being so adapted that the spray mist jets also iripinge on the cutting tracks at an impact velocity of 1G to 39 m/sec.

spray "tiist j et -s can be directed in the direction 05E CUtL..Lting head rotaition on to the cutting tools biting into the rock and thus on to the resulting cutting tracks. The spray rmist jets can alternaitively be directed against the direction of cutting head rotation, on to the cutting tracks of the cutting tools withdrawing from the rock. Howeverr 1- the spray mist jets may also be directed on to both the cutting tools biting into the rock and the cutting tracks of the cutting tools withdrawing from the rock. it is known that a spray m ist jet can be produced either by directirig a water jet centrally into an atomisation nozzle and surrounding it with air for atomisation, or vice j versa. The atomisation nozzle may have a venturi-type constriction and a diffusor, or simply a diffusor. it is also possible to employ spin atomisation. lloreover, the air stream can draw the water into a venturi- type constriction. The invention is based on the discovery that conditions can invariably be set up so that the spray mist jets carry droplets in the specified size range and with such a high kinetic energy that they impinge on the cutting tracks at an impact velocity of 10 to 30 m/sec. In this ways, intensive cooling takes place in the cutting tracksy and the cutting tools likewise undergo corresponding cooling. Moreoverr since the spray mist jets have a relatively high kinetic energy they generate an anti-ignition climate around the working cutting headp as already described. The droplets of large diameter in the siie range specified reach the cutting tracks and. the cutting tools in the form- of droplets, thus producing liquid cooling followed by evaporation cooling when E part tly vaporise. The droplets o.1 Licularly L.hey subsequent small diarmeter vaporise oil their way to the points of i.rapact o the spray mist jet L. i s, and accordingly generate an ant - ignition climate around the working cutting head. The anti ignition effect is particularly marked when the length of the free flight path between the mouths of the associated nozzles and the points of in, pact on the cutting tools and/or tracks is at least 20 cm for the tools and at least 30 cn. for the tracks. - Features of the invention will now be described purely by wax; of example, with reference to the accompanying diagra,-,imatic drawings, in which:- Figure 1 is a side elevation of a gallery driving machine of the type having a cutting arm which can swivel both up and down and horizontally, and whi-ch carries a mushroom type cutting head; Figure la is an enlargement of the ringed part of Figure 1; and Figure 2 is a side elevation of another gallery driving machine having a boom which can move up and down and which carries a rotating cutting roll.

Figure 1 shows a gallery driving machine lp comprising a crawler tractor 2, a turret 3r a cutting arm 4 which can swivel both up and down and horizontally, and a mushroom type cutting head 5 carrying a materialpropelling helix 6r which carries an array of at least 30 cutting tools 7 (see also Figure la) cutting at the'largest diameter at a cutting speed of G.5 to 4 m/sect preferably 2 to 3 m/sec, and producing cutting tracks 9 on the working face when cutting rock and coal.

l.'o z z 1 e spaced round its periphery. A water/air mix.ture under an excess atmospheric pressure of 1 to 2 bar is atomised through -les 11. The water/air -i.i.-..ture is supplied to 1 h-hese nozz he nozzle ring through a conduit 12. The atomised. jets 13 issuing fron, the nozzles 11 impinge on the cutting tools 7 and also on the cutting --jz:cl.,.s 9 wiCh an impact velocity of to 30 m/sec. The atomisation is regulated-to for-m a spray wist with a droplet size range between 1 and 10OkL,-., at a flos; rate deterziined by the nuzziber of cutting tools 7 and corresponding to a water flow rate of 0.2 to 0.5 l/i,-,in and an On the forward end of the cutting arm 4 there is a ring 10 having a pluralit_y of noz--lqs 11 unifor-mly t 1 air flow rate of 00.2 to 1.0 M3/min for each cutting tool engaging with the working face. The length of the f ree flight path of the spray mist jets 13 between the mouths of L the associated nozzles 11 and the points of impact or. the cutting tools 7 and/or tracks 9 is at least 20 cm for the tools-and at least 30 cm for the tracks.

Figure 2 shows another gallery driving machine having a boom 15 which can move up and down- and which carries a cutting head 14 of the cutting roll type. On the periphery of the cutting roll there is a material-propelling helix 6 on which the cutting tools 7 are arrayed. The cutting roll bites into the working face 8, thereby producing a cutting track 9. A plurality of nozzles 11 are mounted on a nozzle bar 16 which extends along the cutting roll and is attached to the boom. The nozzle bar 16 is forked and has one nozzle-bar portion 16a above the cutting roll 14 and a second nozzle-:Dar portion 16b below the cutting roll. A water/air mi,.ture is supplied to the ato,,zisation device through the conduit 12, with a water flow rate of 0.2 to 0.5 1/min and an air flow rate of 0.2 to 1.0 m3/min for each cutting tool. The ato,-,-iisation jets 13 issuing from the nozzles with a droplet size range between 1 and 100 /j-m. impinge on the cutting tools 7 and also impinge on the cutting tracks 9 witZ: an impact velocity of 10 to 30 m/sec. Again,- the length of the free flight path of the spray misit: jets 13 between the nouths of the associated nozzles 11 and the points of impactE. on the cutting tools 7 and/or tracks 9 is at least 20" cm for L.he tools and at least cm f or the tracks.

Claims

1. A method for reducing the ignition risk when operating a gallery driving machine having at least one cutting head arrayed with cutting toolsy whereby water from nozzles mounted in fixed positions on the machiner some distance from the cutting headp is finely atomised and the jets of spray mist issuing from the nozzles are directed on to the cutting head$ wherein for each cutting tool there is supplied a water volume of 0.2 to 0.5 l/min and an air volume of 0.2 to 1.0 m3/min, under conditions whereby the droplet size range in the mist jets is held between 1 and 100pm, the air velocity in the nozzles being so adjusted and the nozzles being so disposed that the spray mLst jets also impinge on the cutting tracks at an impact velocity of 10 to 30 m/sec.

2. A method as in Claim 1, wherein the spray mist jets are directed in the direcition of cutting head roCation on to the cuitting tools biting into the rock.

A method as in Clai;:i 1, %.;herein the spray nList -E cutting head jets are directed against the direction ol ro.'4-.atior.,, on to tile cuCting tracks of the cutting tools withdrawing from the rock.

4. A process as in Clairi lr wherein the spray mist jets are direct-ed on to both t-he cutting tools biting into the rock and the cutting tracks of the cutting tools withdrawing from Che rock.

5. A process as in any one of Claims 1 to 4r wherein the length o1E the free flight path of the spray mist jets between the r.-tou.'&--hs of the associated nozzles and the points 2 0 of in, pact on the cutting tools and/or tracks is at. least- a t cm for the tools and at least 30 cn for the tracks.

6. Gallery driving machines operait-ing -'Che method of any one of Claims 1 to 5 and. substanCially as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Patent Off-lee, State House, 66'71 High Holborn. London WC1R 4TP. Further enpies may be obtaaned from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3PM. Printed by Multiplex techniques ltd, St ILarj Cray, Kent. Con. 1187.