DE19625724A1 - Drilling hammer unit using in sinking boreholes or driving piles - Google Patents

Abstract

The unit contains a hammer (6) and bit (8) working together, and a valve (5) activating the hammer. The valve blocks the drilling fluid pumped through the drilling hammer unit, which is supplied via the drill string (1). The valve is relocated from the hammer, to a region away from it above the hammer. The bit can be brought together with the hollow hammer which can be closed by the valve. A piston space (11) is provided between the valve and the hammer. The valve is spring loaded. The hammer is recovered by hydraulic means.

Description

The invention relates to a hammer drill for performing drilling holes with an oscillating stroke movement a chisel interacting impactor and a valve, with that for activating the impact body via a drill pipe flushing fluids fed to the borehole and pumped through the hammer drill liquid flow can be shut off. Such a hammer drill is also for Suitable for driving piles.

A hammer drill for performing earth drilling is an example as known from EP 0 303 635 B1. This hammer drill is on provided and will be the lower end of a tubular drill string brought into the borehole with this. Through the drill pipe becomes a liquid under pressure or at high speed current introduced into the borehole. This liquid flow serves not just to cool the chisel and to rinse and discharge the drilled rock but also to drive the impact body. Here too is in the lower part of the impact body just before Chisel provided a spring loaded valve. The liquid Current is through the drill pipe through the impact body on the valve  bypassed and emerges from the chisel into the borehole, so as long as the valve is open. As well as the hydrodynamic forces the liquid flowing around the valve is larger than the opening force of the spring, the valve is closed suddenly and the passage of the flushing or cooling liquid through the chisel prevented. The sudden shutdown creates an on the Impact body acting pressure pulse, which affects the hammer drill affects as a lifting movement. The liquid becomes through the stroke movement keitsstrom partially relaxed again, so that the spring force The valve opens again and the liquid flow through the Chisel can flow until the valve closes again and a white tere lifting movement is carried out.

The blow parameters are essential parameters for the drilling progress sequence as well as the single impact energy of the hammer drill in order to achieve an ef to effect fective rock destruction. A disadvantage of the known ten hammer drill is that when closing the valve the entire Liquid column hits directly on the bottom of the borehole where can be achieved by only a relatively low impact frequency. In addition, the valve body is not only the sudden Shut off but also by the stroke movement of the impact body heavily loaded and is therefore a corresponding wear exposed. To the impact body with the drill housing or necessary to connect relatively movable pistons to the drill housing the, screw connections are necessary, which are also by the Pressure impulse or the stroke movement of the impact body correspond to one exposed to the relevant stress. The hammer drill is constructive therefore very expensive to train for a corresponding duration to ensure durability.

Starting from this problem, the above should be described ne hammer drill can be improved.

The problem is solved in that the valve outside the Impact body is arranged.  

Through this training, the valve in the static body of the Hammer drill are suspended and no longer takes part in the lifting movement part of the impact body.

The valve works with the axially movable impact body (piston) together. A piston chamber is provided between the valve and the piston hen, in the downstroke the kinetic energy of the piston the chisel is transferred.

Through this design, the liquid mass flow acts on the impact body (piston) closed by the valve and accelerated the valve-piston system tends towards the chisel. By the sudden deceleration of the velocity of the mass flow (Valve completely closes the passage through the piston) there is a spontaneous increase in pressure in the piston chamber and in the linkage above the hammer and causes an elastic expansion in the linkage and a compression in the rinsing liquid. The one there determined by achievable piston speed together with the Mass of the piston is the system's single impact energy.

The impact body is returned during this training preferably hydraulic. There is at least one in the chisel Throttle point provided so that the fluid pressure in Flow direction in front of the chisel is greater than behind it. By the pressure that acts on the bottom ring surface of the piston this raised. The impact body formed by the piston is consequently separated from the chisel.

An exemplary embodiment of the invention is intended to be illustrated are explained in more detail below. It shows:

Figure 1 shows a hammer drill in longitudinal section in the depressurized state.

Fig. 2, the hammer drill according to FIG. 1 in another operating state.

The hammer drill is connected to the drill string 1 and is in contact with the bottom of the borehole 9 . The hammer drill be consists essentially of the respective interlocking cylinder tubes 3 , 7 , 13 , the chisel 8 arranged at the lower end with a chisel shaft 14 and an axially movable piston 6 (percussion body) guided within the cylinder tubes 7 , 13 and above that Piston 6 arranged valve 5th

Like the chisel 8, the rinsing liquid can flow through the piston 6 . The valve 5 is drawn in Fig. 1 in its uppermost position, in which it is held by the compression spring 2 . The compression spring 2 is supported on a housing-fixed at a heel 4 and the valve 5 provided at the upper end of paragraph 5 above. A piston chamber 11 is formed in the cylinder tube 3 between the valve 5 and the piston 6 .

About the drill string 1 , a flushing fluid is introduced through the hammer drill, which is indicated in the drawing by arrows. The flushing liquid serves on the one hand to cool the chisel 8 and on the other hand to discharge the drilled solids from the borehole 9 . The liquid is pumped into borehole 9 under pressure. It flows around the valve 5 , which is thereby opened further against the spring force. The rinsing liquid flows past the valve 5 and via the piston chamber 11 through the hollow piston 6 and the chisel 8 , in order to exit the hammer drill again via the channels 10 seen at the lower end of the chisel 8 and leading to the outside. In the channels 10 at least one throttle point, not shown here, is integrated, at which the pressure of the flushing liquid drops, so that a higher pressure prevails in the interior of the boring machine than in the borehole. Due to the pressure increase in the drilling tool, the piston 6 is lifted from the chisel shaft 14 and guided into its upper end position, which is defined by suitable stops 15 , 16 . This location is shown in Fig. 2. The force with which the piston 6 is raised is calculated from the liquid pressure and the annular surface 17 of the piston 6 . Due to the narrowing of the flow cross-section between valve 5 and the upper piston surface, valve 5 is deflected further and closes abruptly against piston 6 . The piston is accelerated downward by this ram impact and transfers its energy to the chisel shaft 14 when it hits it.

The decisive factor for the energy with which the blow is carried out is the pressure increase in the free space between the piston 6 . At the time the valve 5 is lifted off, the piston has reached its highest speed and covers the remaining distance until it hits the chisel shaft 14 alone. After the pulse exchange with the chisel 8 , this transfers the energy to the bottom of the borehole, which destroys it.

The return of the piston 6 in the starting position is due to the reaction forces on the bottom of the borehole, the weight of the drill string and the hydraulic pressure in the cylinder space 18 . Both the piston 6 and the chisel shaft 14 are guided axially in the cylinder tube 7 , 13 .

Reference list

1 drill pipe
2 spring
3 cylinder tube
4 paragraph
5 valve
5 a paragraph
6 pistons / impact body
7 cylinder tube
8 chisels
9 borehole
10 channel
11 piston chamber
13 cylinder tube
14 chisel shank
15 stop
16 stop
17 ring surface
18 cylinder space

Claims (7)

1. hammer drill for drilling holes and / or for driving piles with an oscillating stroke movement, with a chisel ( 8 ) interacting impact body ( 6 ) and a valve ( 5 ) with which to activate the impact body ( 6 ) the flushing liquid pumped through the drill hammer and fed to the borehole via a drill pipe ( 1 ) can be shut off, characterized in that the valve ( 5 ) is arranged outside the impact body ( 6 ). 2. Hammer drill according to claim 1, characterized in that the valve ( 5 ) above the impact body ( 6 ) is arranged. 3. Hammer drill according to claim 1 or 2, characterized in that the chisel ( 8 ) can be connected to the hollow valve body ( 6 ) which can be closed by the valve ( 5 ) and between the valve ( 5 ) and the body ( 6 ) a piston chamber ( 11 ) is provided. 4. Hammer drill according to claim 1, characterized in that the valve ( 5 ) is spring-loaded. 5. hammer drill according to one or more of the preceding Ansprü surface, characterized in that the resetting of the impact body ( 6 ) is carried out hydraulically. 6. hammer drill according to claim 5, characterized in that in the chisel ( 8 ) at least one throttle point is provided, since with the liquid pressure in the flow direction in front of the chisel ( 8 ) is greater than behind it. 7. Hammer drill according to claim 1, characterized in that the impact body ( 6 ) from the chisel ( 8 ) is separated.