FR2523202A1 - HAMMER WITH PNEUMATIC DRIVE OF THE TYPE "FOND-DE-TROU" - Google Patents

Abstract

1. Down-the-hole pneumatic drilling hammer, which comprises a tubular body (1) supplied with compressed air and carrying a drilling bit (3) and in which a ramming piston (21) is made to perform a reciprocating movement inside an internal sleeve (7) forming a casing by means of a mechanism for distributing compressed air alternately above and below the ramming piston in such a way that it cyclically strikes the bit and rises again, characterised in that the hammer has two separate sources (16, 18) of compressed air, a high-pressure one and a low-pressure one respectively, the distribution mechanism ensuring alternately the supply of high-pressure air to the upper chamber (51) above the piston (21) so as to project the latter towards the bit, while the lower chamber (50) allows the air to escape, and the supply of low-pressure air to the lower chamber (50) so as to cause the piston (21) to rise again, while the upper chamber (51) allows the air to escape.

Description

The present invention relates to a pneumatic drill hammer, and more

  particularly a hammer of the type "bottom-of-hole", ie

  intended to work at the very bottom of the hole that is being drilled.

  Such devices are therefore arranged at the end of a set of tubes which serve to transmit to it the operating compressed air as well as the thrust and the general rotational movement to regulate the action.

perforation cutter.

  Such pneumatic hammers for working at the bottom of the hole generally comprise a tubular body supplied with compressed air, a distribution mechanism, a striking piston, and a cutter receiving the

  percussion piston shocks to transmit them to the rock.

  fear is mobile in a cylinder formed by an inner shirt, and between

  the liner and the inner wall of the hammer body are protected against

  longitudinals for supplying the compressed air acting on the piston, other passages serving to exhaust the air after its action on

  one or the other face of the striking piston When such hammers are pre-

  seen for an independent supply of a spoil hunting fluid, they com-

  carry an axial connecting piece to the fluid supply pipe through the drill pipe, and an axial tube passing right through the entire hammer assembly, that is to say in particular the striking piston, to come This pneumatic hammer has been described for example in the published French patent.

under number 2 044 939.

  To obtain sufficient efforts to strike the striking piston on the cutter, and therefore on the rock to break, using compressed air under high pressure, under 20 to 25 bar for example Consumption that may be of the order for example 10 to 15 Nm 3 per minute therefore requires the use of compressors high flow under high pressure, ie heavy and bulky equipment It is also expensive equipment, both in value of purchase and capitalization, that in the cost of

  functioning because the energy consumption is important.

  The present invention allows a significant reduction in these costs, and in particular, at the same drilling efficiency, a significant reduction in

energy consumption.

  The invention therefore relates to a pneumatic drill-type drill "bottom-hole", comprising a tubular body supplied with compressed air carrying a perforation cutter, and wherein a striking piston is reciprocated in an inner sleeve forming sleeve by a mechanism for distributing compressed air alternately above and below the striking piston so that it comes cyclically

  knock on the cutting edge and pull up.

  According to the invention the hammer comprises two separate compressed air supplies, respectively at high and low pressure, the distribution mechanism alternately ensuring the supply of high pressure air from the upper chamber above the striking piston to project it to

  cutting with exhaust of the lower chamber, then ltalian

  oe mentation 7 low pressure air from the lower chamber to wind up

  the piston with exhaust of the upper chamber.

  According to a particular embodiment of the invention, the

  low-pressure air from the lower chamber is provided by an inner axial chamber of the striking piston, while the high-pressure air supply of the upper chamber is provided by lights

  through the sheath and longitudinal grooves formed outer-

in the thickness of the sheath.

  The invention will be better understood by referring to a mode of realization

  This particular example is given by way of example and shown in the accompanying drawings. FIG. 1 is a general view in longitudinal section, in two

  parts, of a pneumatic hammer made according to the invention.

  Figures 2 to 5 are partial views that show the posi-

  successive operations of the striking piston during an operating cycle.

  Referring first of all to the two parts of the

  Figure 1, it will be seen that the main body 1 of the hammer is screwed to its

  lower part on a tip 2 in which slides the fluted tail of the perforation cutter 3 The tail of the cutter is stopped in rotation by

  relative to the body, and limited in axial displacement by a tangential key

  4 which relates to a clearance of the tail.

  A cylindrical sleeve 7 internally double the body 1 on pres-

  that its entire length At its lower part the sheath 7 is supported on a spacer ring 8 of generally conical shape, pierced by radial orifices 9, and which -rend itself bearing on the tip 2 Similarly the other end sheath 7 is abutting on a ring 10 provided with ducts

  The ring 10 is held by the end of the connector end.

  rope 13 screwed on the body 1 With its other end the tip 13

  receives the usual parts of connection with the tubes and rods of alimenta-

  The piece 15 which transmits the thrust on the hammer forms a first annular duct 16 around a tube 17; a second annular duct 18 is formed between the inner face of the tube 17 and

a central tube 19.

  By its inner surface the sheath 7 serves as a guide for the piston piston.

  sliding fear 21 which can move freely between a low position as shown in Figure 1 where it is in contact with the end of the tail of the cutter, and a high position as will be seen later

  when describing the operation of the device The upper part

  21 of the crater permanently surrounds the lower part of the tube 17 whose ex-

  full lower end 23 comprises channels 24 which communicate the annular duct 18 with a central chamber 25 inside the batter

  The chamber 25 is extended by two axial ducts 26 and 27, the latter

  denier leading to the bottom of the batter Externally the striker

  fear 21 has a circular groove 28.

  The outer surface of the sheath 7 comprises three series of grooves.

  longitudinal res; to simplify the drawing there is shown here only one groove of each type A first series of upper grooves 30

  communicates the annular chamber 31 which surrounds the ring 10 with

  so many orifices 32 which open inside the sheath A second

  series of lower grooves 34 lead to the annular chamber 35

  turning the lower ring 8; the orifices 36 and 37 pass through the wall of the sheath 7 and open into these grooves 34. Finally, a third series of grooves 39 makes the orifices 40 and 41 pass through.

the wall of the sheath 7.

  It will be noted that the chamber 35, around the ring 8, communicates with the outside of the hammer through the ducts 9, the clearance between the flutes of the cutter and the conjugate grooves of the nozzle 2, and by the chamber 47 which

  communicates with the outside through the exhaust ducts 48.

  The central tube 19 serves the purpose of water used to chase the

  cuttings downhole For this the tube 19 is extended to the lower part

  until it reaches the tail of the cutter which has a central channel

  The penetration of the tube into the tail of the cutter is de-

  completed so that the tube remains engaged regardless of the position of the tail-

  The central channel 43 is elongated by a channel 44 which opens out through orifices 45 at the periphery of the cutting edge.

to drive out the excavations.

  The outer annular conduit 16 is supplied with compressed air at a higher rate.

  pressure, for example under 20 to 25 bar The inner annular conduit

  18 is supplied with compressed air at low pressure, for example under 6 bars.

  The connections of the simultaneous supply of the hammer by the three different fluids, liquid for hunting, have not been shown in the drawings.

  the central tube 19, low pressure air for the duct 18, high air pres-

  These connectors, as well as the structure of the elongate tubes for connection with the surface have already been described, for example, by

  the French patent published under number 2 126 118.

  Referring now to FIGS. 2 to 5, to understand the function

  In FIG. 2, as in FIG. 1 above, the striking piston 21 is shown in the lower position, just after its impact on the tail of the cutter. In this position, the hammer piston is fed with compressed air at two different pressures. high pressure air fills the

  16, the intermediate chamber 49, the ducts 11, the annular chamber

  31, the grooves 30 and the orifices 32; but these, inside the sheath, are closed by the hitter 21 and the high pressure air remains

  trapped in the grooves 30 On the other hand low pressure air

  bank through the conduit 18 passes through the ducts 24 in the chamber 25, and

  there through the conduits 26 and 27 fills the lower chamber 50 under the

  fear 21 The pressure in the lower chamber 50 makes up the frap-

  fear 21 without any reaction other than its own weight because the upper chamber 51 then freely communicates with the exhaust outside the hammer

  through the orifices 36, the grooves 34 and the chamber 35.

  When in his uphill race the batter reaches the

  shown in Figure 3, the low pressure air inlet is interrupted by closing the orifices 24 by the walls of the chamber 26 at the same time the chamber 50 is exhausted through the opening of the openings 37 which

  then make it communicate with the grooves 34.

  Under the impetus given the hitter 21 will continue its upward stroke and the groove 28 will face the orifices 32 and fill with air

at high pressure.

  When the batter reaches the position shown in Figure 4 the

  throat 28, already full of air under high pressure, is directly

  holes 32 and 40, so that by the grooves 39 and the ori-

  these 41 the chamber 51 is filled with air under high pressure.

  The exhaust ports 36 are already closed, the high pressure in the chamber 51 violently pushes the batter 21 down without back pressure since the lower chamber 50 is then exhausted

by the openings uncovered 37.

  During its downward stroke (FIG. 5), the hitter 21 first closes the high-pressure supply of the chamber 51, then puts it into the exhaust by uncovering the orifices 36. tail end of the tailpipe exhaust chamber 50 is

  closed by closing the orifices 37, then the low pressure air is again

  calf brought into the chamber 50 by opening the orifices 24 on the chamber

25, and the cycle can start again.

  We see that each cycle, ie each round trip

  21, only the active phase of the batter's pitch to the tail.

  lant is a consumer of high pressure air, while the inactive phase

  lift only consumes low pressure air; the effort

  dredged by the low pressure in chamber 50 is sufficient to ensure

  the free recovery of the batter who benefits from the effect of

  during the impact on the end of the tail of the cutter The consumption of air at high pressure is generally divided substantially by two,

  allowing the same power of perforation, to use a material

  much less bulky, less expensive to buy and less expensive

  in energy consumption The supply of compressed air under low pressure

  6 bars requires only a connection to a conventional distribution network, or a low-cost compressor unit.

purchase and consumption.

  It will be noted that in the exhaust, both the high pressure air after action in the upper chamber 51 and the low pressure air after working in the lower chamber 50, are found mixed in the chamber 35,

  then at the exit of the hammer in the conduits 48.

  Of course, the invention is not strictly limited to the mode of

  described above as an example, but it also covers

  which would differ only in details,

  alternative embodiments, or by the use of equivalent means.

  Thus, although the above description was made for a

  pneumatic trough with a central feed of flushing fluid,

  would offer the same benefit of reducing energy consumption for a hammer without flushing fluid, which would be removed only

  by the exhaust air coming from the ducts 48.

Claims (4)

REVENDIC Ar IONS   1. Pneumatic "bottom-of-the-hole" type pneumatic hammer, comprising a tubular body (1) supplied with compressed air and carrying a perforation cutter (3), and in which a striking piston (21) is set in motion reciprocating in an inner liner (7) forming a sleeve by a mechanism for dispensing the compressed air alternately above and below the striking piston so that it comes cyclically to hit the cutting edge and up, characterized in that the hammer has two separate power supplies   (16, 18) of compressed air, respectively at high and low pressure, the   distribution canopy alternately supplying the high pressure air supply of the upper chamber (51) above the piston (21) for   project it to the cutter with the exhaust of the lower chamber   (50), then the low pressure air supply of the lower chamber   (50) to raise the piston (21) with exhaust of the upper chamber (51).   Pneumatic hammer according to claim 1,   characterized by the fact that the low-pressure air supply of the chamber   lower chamber is provided by an inner axial chamber (25) of the piston   your hitter (21), while the high pressure air supply of the   upper chamber (51) is provided by lights (32, 40, 41) passing through   the sheath (7) and longitudinal grooves (30, 39) formed   in the thickness of the sheath.   Pneumatic hammer according to claim 1,   characterized by the fact that the exhaust ducts (36, 37), respec-   high pressure air from the upper chamber (51) and the air   low pressure of the lower chamber (50), have a common part   no (34) opening at the bottom of the hammer.   Pneumatic hammer according to one of the claims   preceding, characterized in that it further comprises a conduit   axial "9) flushing fluid feed cuttings.