GB2104945A - Dusting suppressing mineral mining cutter head - Google Patents

Abstract

A cutting head (1) for a mineral mining machine has a plurality of pick boxes (2) each capable of receiving and retaining a radial pick (15) having a water passage (20) extending through the body of an inner end to a location behind a cutting edge (16) of the pick. Each pick box has a housing (8) at the base thereof into which a water passage (7) through the cutting head opens. An elongate jet (12) having a water passage (14) extending longitudinally therethrough is retained and sealed within the housing (8) so as to be capable of limited universal movement relative thereto. A first end of the jet communicates with the water passage (7) through the cutting head and the jet projects generally radially outwardly from the housing into the pick box to be received in a bore (18) in the inner end of a pick. The jet is sealed in the bore by a seal (19) and communicates with the water passage (20) through the pick. The limited universal movement of the jet which is provided by the seals allows movement of the jet as the pick wears in the pick box while retaining the integrity of the water passage. <IMAGE>

Description

SPECIFICATION Cutting head for a mineral mining machine The invention relates to cutting heads for mineral mining machines.

It is particularly applicable to cutting heads for mineral mining machines, for example coal cutting heads, which have a plurality of pick boxes mounted around their circumference, each pick box being capable of receiving and retaining a radial pick which actuaily performs the cutting action on the coal face or other face being worked.

It is customary to spray water onto the leading or cutting face of each pick, and cutting heads are therefore usually formed with a so-called water gallery through which water is fed through a plurality of channels, each channel terminating at its outer end at a region of the cutting head on which a jet is mounted. Water supplied to the cutting edge is effective in suppressing dust.

Apart from dust, a further problem encountered in mining is that of explosion due to the accumulation of an explosive mixture of gases being ignited by hot material produced by the cutting action. This danger is particularly prevalent when the rock being cut includes particularly hard regions, for example regions of quartz or of pyritic material. It ha been found that the hottest region during such cutting occurs in the cut-off particles that are left in the cutting track of the pick, and that these are capable of igniting explosive mixtures some distance behind the pick. It has also been found that spraying of water onto the cutting face of the pick has no cooling effect on these particles.

Recent work has shown that the explosion hazard can be reduced if water is sprayed from the radially outer surface of the pick body behind the cutting edge of the pick. Water injected at this location cools the cut particles as they are formed so reducing risk of ignition, and also has the advantageous effect of cooling the pick itself.

However, significant difficulties have been experienced in conveying water to this location.

An attempt has been made to supply water to the inner end of the pick box and thence through a water passage extending radially along the body of the pick to open from the pick behind the cutting edge thereof. However, it has not proved possible to maintain effective seals as the pick wears and effective water supply to the required area cannot be maintained. The object of the present invention is to overcome this problem.

According to the invention we provide a cutting head for a mineral mining machine, the head having a plurality of pick boxes each capable of receiving and retaining a radial pick having a water passage extending through the body thereof from an inner end of the pick to a location behind a cutting edge of the pick, in which each pick box comprises a housing at the base thereof into which a water passage through the cutting head opens, an elongate jet having a water passage extending longitudinally therethrough, and means retaining and sealing the jet within the housing so as to be capable of limited universal movement relative thereto with a first end of the jet communicating with the water passage through the cutting head and with the jet projecting generally radially outwardly from the housing into the pick box for reception and sealing in a bore in the inner end of a pick located within the box.

According to a further aspect of the invention a cutting head for a mineral mining machine comprises a plurality of pick boxes, a radial pick retained in each of the pick boxes, each pick having a bore extending into the inner end thereof and a water passage extending from the bore through the body of the pick to a location behind a cutting edge of the pick, a housing at the base of each pick box into which a respective water passage through the cutting head opens, an elongate jet associated with each housing, each jet having a water passage extending longitudinally therethrough, means retaining and sealing each jet within its associated housing so as to be capable of limited universal movement relative thereto with a first end of the jet communicating with the respective water passage through the cutting head and with the jet projecting generally radially outwardly from the housing and into the bore in the associated pick, and means sealing the jet in the bore in the pick with the second end of the jet communicating with the water passage through the pick.

In use, the water is supplied through the water passage in the cutting head to the housing. From there water passes through the jet into the water passage of the pick body to issue therefrom behind the cutting edge of the pick. Sealing is effected by the sealing means between the jet and the interior of the housing and by the seal between the jet and the bore at the inner end of the pick. As the pick wears the stem of the pick becomes loose in the pick box and wobbles within the pick box. The wobbling movement is transmitted through the seal to the jet and the jet thus wobbles in the housing. However, this movement is allowed because of the limited universal mounting of the jet within the housing and the seal between the jet and the housing maintains its effectiveness during such movement.

Similarly, the seal between the jet and the bore of the pick will maintain its effectiveness and thus a continued supply of water as required can be maintained even when the pick is showing considerable wear.

In one preferred form of the invention the jet comprises a body and a stem extending generally radially outwardly from the body, the housing has a chamber with opposite first and second openings, the first opening being through a base of the housing and communicating with the water passage through the cutting head, a resilient seating lies within the chamber, the housing and the body of the jet are so shaped that the jet body is insertable into and removable from the chamber through the second opening thereof, the second opening having opposed retaining sections the distance between which is less than a corresponding dimension of the jet body and the resilient seating is made from a compressible material that is deformable during insertion of the jet body to allow the jet body to he located partially beneath the opposed retaining sections in which position the seating is compressed by the jet body and the restoring force due to such compression biases the jet body to engage beneath the opposed retaining sections thereby to hold the jet body in position within the housing with the stem projecting through the second opening and effects a seal that directs water from the chamber to the first end of the water passage through the jet, the seating further being deformable to allow limited universal movement of the jet relative to the housing and to allow removal of the jet from the housing through the second opening therein.

The jet body and stem may be an integral construction, or these elements may be separate.

In the latter case conveniently the radially inner end of the jet stem is received within a bore through the jet body, and a sleeve of waterproof resilient material lines the bore and is a close, sealing fit within the bore and around the jet. The assembly may be held together by adhesive or, desirably, more positive retaining means may be used to hold the stem and the sleeve within the bore even though subjected to very high water pressures.

In order that the invention may be better understood specific embodiments of cutting heads in accordance therewith will now be described in more detail by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-section through a pick and pick box mounted on a cutting head; Figure 2 is a cross-section taken on the line Il-Il of Figure 1; Figure 3 is a side elevation of part of the apparatus taken on the line Ill-Ill of Figure 1; Figure 4 is a cross-section similar to Figure 1 of a second embodiment; and Figure 5 is a cross-section, again similar to that of Figure 1, of a third embodiment.

Figure 1 shows part of a cutting head 1 of a mineral mining machine. Spaced around the periphery of the cutting head are a plurality of pick boxes such as 2, each box being located within a recess 3 within the cutting head and being welded to the head as shown at 4. The axes of the pick box 2 and recess 3 are coincident and extend generally radially of the cutting head. The recess 3 is extended radially inwards to a reduced diameter section 5 and a further reduced diameter section 6 into which opens a water passage 7 extending radially through the cutting head.

A housing 8 is fitted within the section 6 and is secured to the cutting head by welding as at 9. A seal 10 is provided in the interior of the housing and the body 11 of a jet shown generally as 12 is received within the housing. The jet has a stem 13 integral with the body 11 and projecting radially from the housing and into the pick box. A water passage 14 extends longitudinally through the jet.

A pick 1 5 having a cutting tip 1 6 has a stem 17 fitting within the pick box and secured to the pick box by any suitable securing means (not shown).

The inner end of the stem of the pick is formed with a bore 1 8 having a groove within which fits a sealing ring 19. The inner diameter of the bore 18 and the outer diameter of the stem 13 are such that the bore fits easily over the stem with a reasonable clearance between the stem and the bore, sealing between the two being effected by the sealing ring 1 9. The bore 18 communicates with a water passage 20 extending through the body of the pick and opening therefrom at a location 21 at the radially outer part of the pick behind the cutting edge 16.

The housing and jet assembly are shown in more detail in Figures 2 and 3. The housing 8 has a generally cylindrical wall section 22 terminating in an axially outer plane surface 23 and an axially inner plane surface 24 formed with a passage 25 which, when the housing is properly positioned as shown, lies in axial alignment with the radially extending water channel 7 through the cutting head. The passage 25 opens into an interior chamber 26 of the housing in which is located the seal 10, which also forms an annular resilient seating member for the body 11 of the jet 12. The body 11 is a push-fit into the chamber through an opening 27 in the face 23 and co-axial with the chamber.

The shape of the opening 27 is best seen from Figure 2. A shallow channel 28 is formed across the surface 23, the channel having side walls 29 which taper inwardly towards a plane including the axis of the housing. The base of the channel provides two flat faces 30 and 31 each perpendicular to the axis of the chamber and each terminating at opposite sides of an opening into .he chamber. Part of the line of termination at each face is arcuate as at 32 and 33 respectively, and each face is chamfered around its arcuate termination to form walls 34 and 35 of the passageway which taper inwardly towards the chamber.The diameter of of the opposed sections 32 and 33 is less than the maximum diameter of the body 11 of the jei. The axially inner surfaces of the parts 30 and 31 form retaining means such as 36 facing towards the resilient seating 10. The other walls of the opening 27 leading into the chamber are formed by arcuate surfaces 37 and 38 of those parts of the housing which stand above the channel 28 and have the plane surfaces 23. The arcuate surfaces 37 and 38 are chamfered and taper inwardly towards the chamber.

The body 11 of the jet 12 has an axially outer face 39 and an axially inner face 40 joined by a circumferential face 41 which tapers inwardly towards the axially inner face. The body 11 of the jet is fitted into the housing through the opening 27 by sliding the body in over the lip formed by surface 35 so that the axially outer surface 39 engages under the lip formed by surface 34 and the circumferential surface 41 engages the seating member 10. Forcing the jet towards the seating member causes both axial and radial compression of this to an extent such that the face 39 can be moved axially past the lip formed by surface 35 and the jet is then forced by the resilience of the seating into the position shown in Figure 1 where a body engages beneath the surfaces 36.The resilience of the seating holds the body 11 against the surfaces 36 and the jet is thereby retained in position in the housing.

In use, high pressure water is supplied through the water passage 7 and enters the chamber 26 within the housing 8. The water pressure causes a lip 42 of the seating member to seal against the surface 41 of the jet and causes a further lip 43 to seal against the inner surface of the chamber. The pressure also causes the body 11 of the jet to seal firmly against the surfaces 36. The form of the seal is such that a substantially leak-proof channel is formed between the water passage 7 and the water passage 14 extending through the stem 13 of the jet. Water conveyed through the passage 14 enters the bore 18 and thence the water passage 20 through the body of the jet to be sprayed from the jet behind the cutting tip 1 6 thereof The sealing ring 1 9 prevents leakage down the outer surface of the stem.

When initially fitted and during the early part of its working life the stem of the pick 1 5 is a close fit within the pick box 2 and there is virtually no relative movement between the two. However, as wear occurs the pick stem enjoys an increasing freedom of movement within the pick box and so wobbles within the pick box. This wobbling movement is transmitted to the jet 12, which is thus also caused to move relative to the rigidly fixed housing 8. The resilient seating 10 is, however, of such form that the jet is allowed limited universal movement relative to the housing 8 without destroying the effectiveness of the seal due to the lips 42 and 43. Thus, water will continue to be supplied through the passage 20 even when the picks become worn, without any significant leakage from the supply path.

Referring now to Figure 4 this shows a second embodiment of cutting head, similar in a number of respects to that of Figure 1. Accordingly, corresponding parts are indicated by the same reference numerals as used in Figure 1.

In this embodiment the bore 18 at the inner end of the stem of the pick is fitted with a sealing sleeve 51.The inner diameter of the bore 18 and the outer diameter of the sleeve 51 are such that the sleeve is a close, sealing fit within the bore.

The sleeve 51 surrounds the radially outer part of the stem 13 of the jet and the inner diameter of the sleeve 51 and the outer diameter of the stem 13 are such that the stem is a close, sealing fit within the sleeve. The sleeve 51 is shaped so as to provide a flared opening 52 to facilitate receipt of the stem 13 and to facilitate tilting movement of the stem relative to the seal. The seal may be of a hard, waterproof resilient rubber. A washer 53 is inserted into the bore 1 8 over the end of the sleeve 51 and is secured in position by clenching the material of the stem 1 7 over the washer at a number of spaced points around the opening of the bore 1 8 as indicated at 54.

This embodiment differs further from the embodiment of Figure 1 in the construction of the jet, which has a separate body 11 and stem 14 rather than the integral construction of Figure 1.

However, the shape of the body 11 is similar to that of the Figure 1 embodiment, the housing 8 is identical to that of the Figure 1 embodiment and the locating and sealing of the body 11 within the housing is also identical to that of the Figure 1 embodiment.

In this embodiment, however, the body 11 of the jet has a tubular extension 55 with an inwardly directed flange 56 at the radially outer end thereof. The flange 56 overlies a resilient sleeve 57 into which passes the stem 14, the sleeve sealing against the outer surface of the stem and against the inner surface of a bore 58 in the body 11. The radially inner end of the stem 14 has an outwardly swaged part 59 that lies below the sleeve 57. A washer 60 is located in the open end of the bore 58 and is held in position by clenching the material of the body 11 at a number of spaced points such as 61.

To assemble the described structure the housing 8 and pick box 2 are welded to the cutting head. The seal 10 is inserted into the housing 8.

The jet is assembled by inserting the resilient sleeve 57 into the bore 58 from the lower end thereof and then inserting the stem 14 from the lower end to pass through the sleeve. The washer 60 is then inserted and the clenching operation performed to lock the washer and thus the swaged end 59 of the stem and the sleeve 57 in position in the bore 58. These parts are prevented from moving radially outwardly from the bore by the inwardly directed flange 56. The jet is then inserted into the housing as already described with reference to Figure 1. The sleeve 51 is inserted into the bore 1 8 of the pick, the washer 53 is inserted over the sleeve and the clenching operation is then performed to lock both the washer and the sleeve in position in the bore 1 8.

The pick is then inserted into the pick box, the outer end of the stem 14 being received within the sleeve 51 and the pick box then being secured in position.

It will be apparent that the assembly operates in a similar manner to that of Figure 1. However, an extra degree of freedom for the stem 14 of the jet is provided by the resilient sleeve 57 that is present between the stem 14 and the jet body 11 and accordingly the assembly enjoys greater tolerance to wear without destroying the effectiveness of the seal due to the lips 40 and 41 of the resilient seating 20. If for any reason the passage 20 should become blocked then water pressure will build up in the supply path. Even if this happens the assembly will remain intact to confine the water to the supply path. Thus, the sleeve 51 cannot be forced from the bore 1 8 due to the clenching over the washer 53. The stem 14 cannot be forced out of the jet body 11 due to the presence of the swaged end 59 and the retaining flange 60 clenched in position at 61.The head 11 of the jet cannot be forced from the housing 8 due to the engagement of the surfaces 31 and 33. The assembly has been tested at a pressure of 750 psi and remained intact at that pressure without leakage from the supply path. The retention of the stem 14 within the body 11 and of the body 11 within the housing 8 also prevents any part of the assembly being forced from the cutting head should the assembly be placed under pressure without the pick 1 5 being present in the pick box.

It will be apparent that there are other ways in which a jet stem may be anchored to a jet body so as to be safe even under fault conditions and yet still allow some movement between the stem and the jet body. There are also alternative methods by which the stem 14 may be seated and sealed in the end of the pick. In particular the washer 53 may be dispensed with and the sleeve 51 alternatively held in position within the bore 1 8 by forming the stem 14 with an external flange which, when assembled, will bear on the surface 62 of the pick 1 7 to close the bore 18.

Figure 5 shows a simplified embodiment of the invention and again parts corresponding to those of Figure 1 are indicated by the same reference numerals. In this embodiment the housing 8 has a base 65 and side walls 66, the cross-section of the housing being circular, although other cross sections would be possible. A jet 12 having an internal passage 14 extends from the housing 8 to be received in a bore 18 in the pick 1 5. The radially inner end 67 of the jet lies in contact with the base of the housing, with the water passage 7 through the cutting head. The radially outer end of the housing is received within a sealing sleeve 68 within the bore 1 8 of the pick, the sleeve having a flared opening 69 to facilitate insertion of the jet and also to facilitate tilting movement of the jet relative to the sleeve.The sleeve may be made of a hard, waterproof resilient rubber, and there is no need for it to be bonded either to the jet or to the bore 1 8. The jet 14 is retained and sealed within the housing 8 by a seal 70 which is desirably bonded to the jet by moulding or by means of a suitable adhesive. The seal 70 is desirably a push fit into the housing 8 and may if desired be formed with a fluted outer circumferential surface in order to increase the frictional grip between the housing and the seal. The seal may be of any suitable resilient material, neoprene being presently preferred.The seal 70 has a dished radially outer face 71 and has its region of least radial thickness immediately surrounding the jet 1 2. This facilitates tilting movement of the jet relative to the body of the seal and also ensures that the free length of the jet between its plane of engagement with the seal 70 and its plane of engagement with the sealing sleeve 68 is sufficient to allow the desired freedom of movement of the jet.

Assembly is a straight-forward matter, as is the removal and replacement of worn parts. After welding, the pick box 2 and the housing 8 are fixtures on the cutting head. The jet 12 with the seal 70 bonded thereto is inserted through the pick box and into the housing 8, being pushed into a position where the base of the seal engages the base of the housing. The pick 16 with the sealing sleeve 68 fitted therein is then inserted into the pick box, with the tip of the jet 12 locating in the seal 68. The pick box is then pushed home to the position shown in the drawings. In use, high pressure water is supplied through the water passage 7 and passes through the jet 12 then through the water passage 20 through the body of the pick to be sprayed from the pick behind the cutting tip 1 6 thereof. The seals 70 and 68 effectively prevent leakage of water from this path and the seals are kept in their respective positions by the location of the pick in the box. As with the preceding embodiments the wobbling movement of the pick stem as the pick wears is allowed by the limited universal movement relative to the fixed housings that are provided by the resilient seals 70 and 68.

Although a number of preferred forms for mounting a jet for limited universal movement relative to a housing while maintaining a sealing effect therebetween have been iliustrated, it will be appreciated that alternative embodiments are possible. In particular, forms of the seals illustrated in the drawings may be changed from those shown and other modifications to the various mountings will be apparent to those skilled in the art.

Claims (20)

1. A cutting head for a mineral mining machine, the head having a plurality of pick boxes each capable of receiving and retaining a radial pick having a water passage extending through the body thereof from an inner end of the pick to a location behind a cutting edge of the pick, in which each pick box comprises a housing at the base thereof into which a water passage through the cutting head opens, an elongate jet having a water passage extending longitudinally therethrough, and means retaining and sealing the jet within the housing so as to be capable of limited universal movement relative thereto with a first end of the jet communicating with the water passage through the cutting head and with the jet projecting generally radially outwardly from the housing into the pick box for reception and sealing in a base in the inner end of a pick located within the box.

2. A cutting head for a mineral mining machine, the cutting head comprising a plurality of pickboxes, a radial pick retained in each of the pick boxes, each pick having a bore extending from the bore through the body of the pick to a location behind a cutting edge of the pick, a housing at the base of each pick box into which a respective water passage through the cutting head opens, an elongate jet associated with each housing, each jet having a water passage extending longitudinally therethrough, means retaining and sealing each jet within its associated housing so as to be capable of limited universal movement relative thereto with a first end of the jet communicating with the respective water passage through the cutting heat and with the jet projecting generally radially outwardly from the housing and into the bore in the associated pick, and means sealing the jet in the bore in the pick with the second end of the jet communicating with the water passage through the pick.

3. A cutting head according to claim 2 in which the means sealing the jet in the bore of the pick is a sleeve of waterproof, resilient material lining the bore and a close, sealing fit within the bore and around the jet.

4. A cutting head according to claim 3 in which the sleeve is shaped to provide a flared opening for the jet at the radially inner end of the bore.

5. A cutting head according to claim 3 or claim 4 and including stop means preventing movement of the sleeve out of the radially inner end of the bore.

6. A cutting head according to any one of the preceding claims in which the jet comprises a body and a stem extending generally radially outwardly from the body, the housing has a chamber with opposite first and second openings, the first opening being through a base of the housing and communicating with the water passage through the cutting head, a resilient seating lies within the chamber, the housing and the body of the jet are so shaped that the jet body is insertable into and removable from the chamber through the second opening thereof, the second opening having opposed retaining sections the distance between which is less than a corresponding dimension of the jet body, and the resilient seating is made from a compressible material that is deformable during insertion of the jet body to allow the jet body to be located partially beneath the opposed retaining sections, in which position the seating is compressed by the jet body and the restoring force due to such compression biases the jet body to engage beneath the opposed retaining sections thereby to hold the jet body in position within the housing with the stem projecting through the second opening and effects a seal that directs water from the chamber to the first end of the water passage through the jet, the seating further being deformable to allow limited universal movement of the jet relative to the housing and to allow removal of the jet from the housing through the second opening therein.

7. A cutting head according to claim 6 in which the resilient seating is so shaped that, when liquid under pressure is supplied through the housing, part of the seating effects a seal communicating the water passages in the cutting head and in the jet and part effects a seal against the wall of the chamber.

8. A cutting head according to claim 6 or claim 7 in which the chamber and the retaining part of the jet are substantially circular in cross-section, the seating member is annular, and the opposed sections of the opening are diametrically opposed arcuate sections coaxial with the chamber and with a diameter less than the maximum diameter of the retaining part of the jet.

9. A cutting head according to any one of claims 6 to 8 in which the jet body and stem are an integral construction.

10. A cutting head according to any one of claims 6 to 8 in which the radially inner end of the jet stem is received within a bore through the jet body, and a sleeve of waterproof resilient material lines the bore and is a close, sealing fit within the bore and around the jet.

11. A cutting head according to claim 10 in which the radially outer end of the bore in the jet body is of reduced diameter to prevent movement of the sleeve out of the radially outer end of the bore.

12. A cutting head according to claim 10 or claim 11 in which the radially inner end of the jet stem has an externally enlarged section engaging the radially inner end of the sleeve to prevent movement of the jet stem radially outwardly of the sleeve.

13. A cutting head according to any one of claims 10 to 12 and including stop means preventing movement of the sleeve and/or the jet stem out of the radially inner end of the bore in the jet body.

14. A cutting head according to any one of claims 1 to 5 in which the housing has a base and side walls, the base having an opening communicating with the water passage through the cutting head, and the jet is retained within the housing by a resilient sealing member which is a close, sealing fit within the side walls of the housing and around the jet.

1 5. A cutting head according to claim 14 in which the first end of the jet lies in contact with the base of the housing with the water passage through the jet in alignment with the water passage through the cutting head, and the sealing member is in contact with the base of the housing.

1 6. A cutting head according to claim 14 or 1 5 in which the sealing member is bonded to the jet.

1 7. A cutting head according to any one of claims 14 to 16 in which the sealing member has a dished radially outer face and has its region of least radial thickness immediately surrounding the jet.

18. A cutting head for a mineral mining machine, substantially as herein described with reference to Figures 1 to 3 of the accompanying drawings.

19. A cutting head for a mineral mining machine, substantially as herein described with reference to Figures 2 to 4 of the accompanying drawings.

20. A cutting head for a mineral mining machine, substantially as herein described with reference to Figure 5 of the accompanying drawings.