GB2173721A - Drill with fluid jet emission - Google Patents

Abstract

The drill 1, for penetrating rock or mineral structure, has a rotary output member 3 projecting from a casing 2 and driven by a liquid-pressure-operable motor 6. Valve means 11 controls the supply of pressure liquid to the motor and, simultaneously, to a liquid-pressure intensifier 29 housed within the casing. Liquid under intensified pressure which passes from the intensifier is conducted through passage means 64, formed in the output member and in a drill bit, to nozzles in the drill bit. This liquid is discharged through the nozzles thus to form jets which have an eroding effect on the structure being penetrated by the drill bit. The intensifier has a barrel 28 integral with the member 3, and contains capsules which align, during rotation, successively with an input port plate 37 where a pressure surge is created for the passage 64, and an output port plate 40. <IMAGE>

Description

SPECIFICATION Drilling devices This invention relates to drilling devices and more particularly to those in which drilling, for example of rock or mineral structure, is achieved by mechanical penetration and by the effect of a high pressure jet of liquid which impinges against that structure in the vicinity of said penetration thus to erode the material being worked.

Hitherto certain such drilling devices have required the provision of separate power packs for effecting mechanical driving of the drilling head and for producing the high pressure jet of liquid.

This has resulted in somewhat bulky equipment which has been found disadvantageous in confined areas, for example in mines, when drilling holes for roof bolts and the like, and then used adjacent roof supports, conveyors and mining machines which themselves occupy a large proportion of the available space.

The invention as claimed is intended to provide a remedy. It solves the problem of how to design a drilling device in which the need for bulky driving equipment is avoided.

According to this invention a drilling device, suitable for use in penetrating rock or mineral structure and the like, includes a casing, a rotary output member which projects from said casing and which is adapted to receive a drill bit itself having cutting edges at its free end portion, a liquid-pressure-operable motor mounted on the casing and adapted to drive said output member, and valve means capable of controlling the supply of liquid under pressure to said motor and, simultaneously, to a liquid-pressure intensifier housed within said casing, liquid under intensified pressure which passes from said intensifier being conducted through passage means, formed in said output member and in said drill bit, to nozzles in said drill bit adjacent said cutting edges thereof and being discharged through those nozzles thus to form jets which have an eroding effect on the structure being penetrated by the drill bit.

The intensifier may include a barrel which is rotatable in the casing by said motor about an axis coincident with the rotational axis of said output member, said barrel incorporating a plurality of differential area intensifier capsules each housed in respective bores which may be equi-circumferentially spaced around the barrel with their axes parallel to the rotational axis of the barrel.

The casing may be provided with a first floating port plate and with a second floating port plate with each of which said bores successively come into registry on rotation of said barrel, liquid under pressure being supplied to said first port plate through passage means taken from said valve means and liquid successively exhausing from said bores through said second port plate passing through further passage means and said valve means to return.

The liquid-pressure-operable motor is preferably of rotary type, for example intermeshing gear type, and axis of one of the gears of which is coincident with the axis of said barrel and output member.

A restrictor may be provided in said further passage means and, from a point upstream of the restrictor, branch passage means taken to said intensifier capsules whereby an intermediate pressure is constantly applied to those capsules in order to effect exhaust of liquid from each of said bores as successively they move into registry with said second floating port plate.

Each said intensifier capsule may be of cylinderand-plunger type, the cylinder thereof being itself slidable in a sleeve, held fast in its respective bore, and with respect to the respective said plunger which is also held fast in that bore.

The drilling device may include a pistol-type grip affording portability and ready manual use. In this case the grip may include a trigger for operation of said valve means.

The grip may be connectible to a supply and return hose, for example through the intermediary of a staple lock coupling or the like.

The output member preferably includes a chuck for receiving said drill bit, the connection including liquid-pressure sealing means.

The advantages offered by the invention are mainly that a compact and readily transportable drilling device is provided in which the same liquid-pressure supply is used for both powering the motor and for charging the intensifier to produce the required high pressure liquid which is discharged at the drill bit.

One way of carrying out the invention is described in detail below with reference to the accompanying drawings which illustrate only one specific embodiment, in which: Figure 1 is an elevation of a drilling device in accordance with the invention showing part of the drill bit in cross-section, and Figure 2 is an enlarged cross-sectional view of part of the drilling device shown in Figure 1.

Referring to the drawings, the drilling device 1, which is suitable for penetrating rock or mineral structure and the like, includes a casing 2 and a rotary output member 3 which projects from the casing and which is provided with a chuck 4 which itself receives a drill bit 5. A liquid-pressure-operable motor 6 of intermeshing gear type is mounted on casing 2.

A pistol-type grip 7 is secured to casing 2 and includes a trigger 8 pivotally-mounted at 9 and in engagement with displaceable element 10 of control valve means 11 for the drilling device. This element is movable from its inoperative position to a first position for initiating operation of motor 6 and then to a second position in which, additionally, liquid-pressure intensification in the device is initiated as hereinafter described.

A supply and return hose 12 which is connectible to a suitable source of liquid under pressure and to reservoir means (both not shown) is attached to the lower end in Figure 1 of grip 7 by a staple lock coupling 13, the two coaxial passages 14, 15 within the hose being thereby sealingly and respectively connected to pressure supply passage 16 and re turn passage 17 in the grip which connect with valve means 11.

Valve means 11 is connected to the inlet port 18 of motor 6 through a first liquid-pressure supply passage 19 and the outlet port 20 of the motor is connected through passages 21, 22, 23 to valve means 11. A restrictor 24 is provided in passage 21 and a branch passage 25 is taken from passage 21 at a point upstream of this restrictor to a central passage 26 passing through the motor and through its output shaft 27 which extends from one of the two gears of the motor. Pressure in passage 26 is maintained at a desired intermediate value between motor inlet pressure and return pressure.

Shaft 27 is suitably splined to drive a barrel 28 which forms part of a liquid-pressure intensifier 29, the rotational axis 30 of which is coincident with the rotational axis 31 of shaft 27 and the rotational axis 32 of rotary output member 3. Barrel 28 is formed integrally with member 3 and is supported at its left-hand end in bearing 33 and at its right hand end in bearing 34.

Barrel 28 includes an even number of circumfer entially equi-spaced bores 35, two of which are shown. In this embodiment there are eight such bores and the longitudinal axis 36 of each bore is parallel to the axis 30.

A floating annular supply port plate 37 mounted in bore 38 in casing portion 39 is in sealing and sliding engagement with the left-hand face of bar rel 28, while a floating annular return port plate 40 mounted in bore 41 in portion 39 is in sealing and sliding engagement with that left-hand face of the barrel. Bore 38 is open to a second liquid-pressure supply passage 42 taken from valve means 11, while bore 41 is open to a short passage 43 which connects with passage 22.

When the barrel is so positioned that one bore 35 is in exact coaxial registry with port plate 37, the diametrically opposite bore 35 is in exact coax ial registry with port plate 40.

Each bore 35 is provided with a sleeve 44 suita bly held fast therein which bears at its right-hand end against the slotted flange 45 formed on the plunger 46 of a plunger-and-cylinder device 47 which forms a differential area intensifier capsule.

The plunger 46 is provided with a through passage 48. A seating 49 at the right-hand end of this pas sage is engageable by a ball 50 loaded by coil spring 51.

The cylinder 52 of device 47 is slidable in sleeve 44, its movement to the left being limited by stop 53. A port 54 is provided in cylinder 52 and a ball 55 is loaded into engagement therewith by a coil spring 56.

Passage 26 is in constant communication through radial passages as at 57/58 and slots 59 with annular chambers 60 of devices 47 thus pro viding a liquid spring effect at an intermediate pressure upon all the cylinders 52, biassing them to the left in the drawings.

Each passage 61, which houses spring 51 and into which passages 48 can open when ball 50 is lifted from its seating 49, opens into a respective radial passage 62. All the passages 62 open through liquid transfer muff 63 into passage 64 in output member 3 and thence into passage 65 in drill bit 5. Passage 65 opens into ports 66, 67 which terminate in nozzles 68, 69 in the free end of bit 5 adjacent the cutting edges 70, 71 thereof.

In operation of the drilling device 1, assuming the hose 12 is correctly connected by staple lock coupling 13 to grip 7, and pressure liquid, for example water, is supplied from the pressure source (not shown) through passages 14, 16 to valve means 11, the device is in readiness for use, for example for drilling holes in the roof of a mine to enable roof bolts or anchors to be fitted into such holes. When the drill bit is manually correctly positioned for drilling such holes, trigger 8 is depressed and element 10 of valve means 11 is displaced to its first position so that pressure liquid, at for example 2000 p.s.i., is directed into passage 19. In consequence motor 6 is energised and its output shaft 27 is rotated causing barrel 28 of intensifier 29 to rotate about axis 30.Liquid exhausting from motor 6 passes through passage 21, restrictor 24, passages 22, 23, valve means 11, passage 17 and passage 15 in hose 12, and thence returns to reservoir. Hence drill bit 5 is rotated and mechanical drilling commences. Trigger 8 can now be further depressed so that element 10 is moved to its second position so that pressure liquid passes not only to the motor but also into the passage 42. From here it passes into port plate 37 and into whichever bore 35 is in registry with that plate. Initially ball 55 of the respective plunger-andcylinder device 47 is moved away from its port 54 against spring 56, thus admitting a charge of liquid into cylinder 52 and through passage 48. As the pressure balance across port 54 ball 55 is urged back into sealing engagement with the port by spring 56.Continued application of pressure at 2000 p.s.i. on the full area of the left-hand face of cylinder 52 causes movement of the cylinder to the right in sleeve 44 against the intermediate pressure constantly maintained in chamber 60, creating such pressure intensification that liquid is discharged under extremely high pressure, of the order of 30,000 p.s.i., through valve 49/50 into passages 61, 62, through muff 63 and into passages 64, 65 and ports 66, 67 for discharge from nozzles 68, 69.

As such pressure intensification is occurring in that device 47 momentarily in registry with port plate 37, the device 47 momentarily in registry with port plate 40 is permitted to extend. That is its cylinder 52 is permitted to move to the left under the intermediate pressure maintained in chamber 60 thereby discharging liquid, trapped in sleeve 44 and in the extreme left-hand portion of respective bore 35 since passing from registry with port plate 37, through port plate 40 and passage 43 so that it joins the discharging flow from the motor 6 to return by way of passages 22, 23, 17, 15.

Thus with the motor driving barrel 28 and therefore the drill bit 5, at for example a speed of 500 r.p.m., as the differential area capsules formed by the plunger-and-cylinder devices 47 of the bores 35 successively pass port plate 37, the passages 64, 65 and ports 66, 67 are charged with successive high pressure pulses resulting in high velocity liquid jets from the nozzles 68, 69 adjacent the cutting edges 70, 71.

Thus the mechanical cutting of the mineral material by the cutting edges of the drill bit is assisted to a very substantial extent by the eroding effect on the mineral material of the high pressure liquid jets issuing from the nozzles 68, 69.

As soon as the drill bit is withdrawn from the hole which has been drilled by the drilling device, the reacting mineral surfaces for the discharging jets are no longer impinged by those jets. This instantly has the effect of reducing the pressure intensification provided by devices 47 and thus the system is effectively off-loaded. Stopping of motor 6 and thus of drill bit 5 is effected by full release of the trigger 8.

The invention is not limited to the provision of a pistol-type grip and trigger as above described with reference to the drawings, as in other embodiments of the invention other means of supporting the drilling device and of operating the control valve means may with advantage be provided.

Also, the invention is not limited to the provision of eight bores with intensifier capsules as in the embodiment above described with reference to the drawings, as in other embodiments any other suitable number of bores with intensifier capsules may be provided. Further, the invention is not limited to the provision of a single floating supply port plate and a single floating return port plate, as in alternative embodiments any other suitable number of each of these port plates may instead with advantage be provided.

Again, although in the embodiment above described with reference to the drawings the motor is of intermeshing gear type, in other embodiments of the invention liquid-pressure-operable motors of other suitable type, for example of roll-vane or sliding-vane type, may instead be provided.

Claims (15)

1. A drilling device, suitable for use in penetrating rock or mineral structure and the like, including a casing, a rotary output member which projects from said casing and which is adapted to receive a drill bit itself having cutting edges at its free end portion, a liquid-pressure-operable motor mounted on the casing and adapted to drive said output member, and valve means capable of controlling the supply of liquid under pressure to said motor and, simultaneously, to a liquid-pressure intensifier housed within said casing, liquid under intensified pressure which passes from said intensifier being conducted through passage means, formed in said output member and in said drill bit, to nozzles in said drill bit adjacent said cutting edges thereof and being discharged through those nozzles thus to form jets which have an eroding effect on the structure being penetrated by the drill bit.

2. A device as claimed in Claim 1, wherein said intensifier includes a barrel which is rotatable in the casing by said motor about an axis coincident with the rotational axis of said output member.

3. A device as claimed in Claim 2, wherein said barrel incorporates a plurality of differential area intensifier capsules each housed in respective bores which are equi-circumferentially spaced around the barrel with their axes parallel to the rotational axis of the barrel.

4. A device as claimed in Claim 3, wherein said casing is provided with a first floating port plate and with a second floating port plate with each of which said bores successively come into registry on rotation of said barrel, liquid under pressure being supplied to said first port plate through passage means taken from said valve means and liquid successively exhausting from said bores through said second port plate passing through further passage means and said valve means to return.

5. A device as claimed in any one of Claims 2 to 4, wherein said liquid-pressure-operable motor is of rotary type.

6. A device as claimed in Claim 5, wherein said motor is of intermeshing gear type.

7. A device as claimed in Claim 6, wherein the axis of one of the gears of said motor is coincident with the axis of said barrel and output member.

8. A device as claimed in Claim 4, wherein a restrictor is provided in said further passage means and, from a point upstream of the restrictor, branch passage means is taken to said intensifier capsules whereby an intermediate pressure is constantly applied to those capsules in order to effect exhaust of liquid from each of said bores as successively they move into registry with said second floating port plate.

9. A device as claimed in any one of claims 3, 4 and 8, wherein each said intensifier capsule is of cylinder-and-plunger type, the cylinder thereof being itself slidable in a sleeve, held fast in its respective bore, and with respect to the respective said plunger which is also held fast in that bore.

10. A device as claimed in any one of the preceding claims, wherein said device includes a pistol-type grip.

11. A device as claimed in Claim 10, wherein said grip includes a trigger for operation of said valve means.

12. A device as claimed in either Claim 10 or Claim 11, wherein said grip is connectible to a supply and return hose.

13. A device as claimed in Claim 12, wherein connection of said grip to said hose is through the intermediary of a staple lock coupling.

14. A device as claimed in any one of the preceding claims, wherein said output member includes a chuck for receiving said drill bit.

15. A drilling device substantially as hereinbefore described with reference to the accompanying drawings.