Rotary drilling tool and method for producing a bore in the ground

Abstract

The invention relates to a drilling tool and a method for producing a bore in the ground, in which method ground material is carried away by a removal device on the underside of a main body of the drilling tool, flushing air is supplied by a feeding device into the bore, which is filled with drilling fluid, in the area of the removal device and ground material carried away by means of the flushing air is transported away through a discharge line. According to the invention, the ground material is transported to a receiving area in an upper section of the main body. A collecting hood is provided above the receiving area, which closes off the receiving area at the top, forming an air collecting space in which air collects. An outlet valve by means of which air is discharged from the air collecting space is arranged on the collecting hood.

Claims

1. A rotary drilling tool for producing a bore in the ground with a base body, a removal means arranged on an underside of the base body for removing ground material, a supply means for supplying flushing air into the region of the removal means and a discharge line for discharging removed ground material and drilling suspension, which can be conveyed away by the flushing air, wherein in an upper section of the base body a receiving region for receiving the removed ground material from the discharge line is provided, in that above the receiving region a collecting hood is arranged which closes off an air accumulation space above the receiving region in the upward direction, and in that on the collecting hood a drain valve is arranged which is designed for the targeted discharge of air from the air accumulation space.

2. The rotary drilling tool according to claim 1, wherein the drain valve is connected to an exhaust air line, with which air can be discharged from the bore to the ground surface.

3. The rotary drilling tool according to claim 1, wherein a controller for the controlled actuation of the drain valve is provided.

4. The rotary drilling tool according to claim 3, wherein the controller has a sensor which, on reaching a predetermined filling level in the collecting hood, actuates the control means to open the drain valve.

5. The rotary drilling tool according to claim 1, wherein the supply means includes a supply line for flushing air, the supply line leading from outside the borehole to the underside of the base body with the removal means.

6. The rotary drilling tool according to claim 1, wherein the removal means has axially movable hammers.

7. The rotary drilling tool according to claim 1, wherein a connecting means for connecting the rotary drilling tool is arranged above the collecting hood.

8. The rotary drilling tool according to claim 1, designed for producing a drill core and for receiving the drill core in the interior of the tubular base body.

9. A drilling apparatus for producing a bore in the ground, the drilling apparatus being provided with the rotary drilling tool according to claim 1.

10. A method for producing a bore in the ground with the rotary drilling tool, in particular according to claim 1, wherein ground material is removed with the removal means on an underside of the base body of the rotary drilling tool, flushing air is supplied, via the supply means, to the bore filled with drilling suspension into the region of the removal means and removed ground material is conveyed away via a discharge line via the flushing air, wherein the removed ground material is conveyed to the receiving region which is arranged in the upper section of the base body, above the receiving region, the collecting hood is provided which closes off the receiving region in the upward direction by forming the air accumulation space, in which air accumulates, and on the collecting hood, the drain valve is arranged, with which air is discharged from the air accumulation space.

11. The method according to claim 10, wherein the drain valve is opened and closed by being controlled by a controller.

Description

(1) The invention is described further hereinafter by way of a preferred embodiment illustrated schematically in the accompanying drawings, wherein show:

(2) FIG. 1 a perspective view of a rotary drilling tool according to the invention;

(3) FIG. 2 a cross-sectional view of the rotary drilling tool of FIG. 1; and

(4) FIG. 3 a side view of the rotary drilling tool of FIGS. 1 and 2 with different positions of the collecting hood.

(5) A rotary drilling tool 10 according to the invention for producing a bore in the ground is explained hereinafter in conjunction with FIGS. 1 and 2. The rotary drilling tool 10 has a base body 12 with a removal means 20 on the underside of the base body 12. The cylindrical base body 12 is of tubular design with a central drill core receiving part 14. The removal means 20 is of annular design with several disk-shaped hammers 22. The hammers 22 are designed as so-called pneumatic hammers that are moved back and forth axially through the feeding of pressurized air, whereby percussive impulses are exerted onto the in-situ ground in order to remove hard ground material.

(6) On an upper side of the base body 12 the rotary drilling tool 10 has a central drill rod 40 with an upper connecting means 42 that is designed as a so-called Kelly box. This serves for the attachment of further drill rod elements to transmit a torque from a non-depicted drilling apparatus to the rotary drilling tool 10.

(7) Via a supply means 30 pressurized air is fed from the drilling apparatus to the base body 12. Via an upper supply line 32 pressurized air is fed into an inner line duct 44 in the drill rod 40. Via an intermediate line 34 the inner line duct 44 in the drill rod 40 is line-connected to a transverse duct 35 in the base body 12. From the transverse duct 35 the pressurized air can be directed through a central tube 36 on the base body 12 to a transversely running distribution line 38 and subsequently to vertically running distribution lines 39 that lead to the drive units of the hammers 22.

(8) The pressurized air spent during actuation of the hammers 22 is directed into the bore filled with suspension so as to convey the stripped ground material away. The pressure fluid emerging at the lower end regions of the hammers 22 directs the removed ground material to discharge openings 24 on the underside of the base body 12. From the discharge openings 24 the removed ground material, together with the emerging flushing air and sucked-in drilling suspension, can flow vertically upwards through a discharge line 25 to the upper end of the cylindrical base body 12. To assist the flow and a suction effect pressurized air can flow via one or several connecting ducts 26 directly from the vertical distribution line 39 over into the vertical discharge line 25.

(9) On the upper end of the discharge lines 25 bends 28 with downward-directed outlet openings are provided so that the discharged ground material is conveyed in a downward-directed manner into a cylindrical receiving region 18 on the base body 12. In this receiving region 18 the solid constituents of the discharged suspension can sediment downwards onto an intermediate floor 16 of the rotary drilling tool 10. Conversely, air emerging from the bends 28 can flow upwards along the drilling axis.

(10) According to a finding of the invention the air flowing freely upwards can lead to a destabilization of the borehole wall of the produced bore. To counteract this, in the rotary drilling tool 10 according to the invention a collecting hood 50 with a sliding sleeve 52 is supported in a vertically displaceable and rotatable manner along a cylindrical guide section 41 of the drill rod 40. The collecting hood 50 has a circular entrance region 53, the external diameter of which substantially corresponds to the diameter of the bore. The collecting hood 50 encloses an air accumulation space 52, in which upward-flowing air is received. An upper region of the collecting hood 50 is provided with a tapering 54 that merges into an exhaust air line 62 with a drain valve 60. The collecting hood 50 is supported in a rotatable manner relative to the base body 12. Alternatively, it can also be connected in a torque-proof manner to the base body 12.

(11) Initially, the drain valve 60 is closed until a sufficient amount of air has accumulated in the air accumulation space 52 of the collecting hood 50. By means of a non-depicted control the drain valve 60 is opened at certain points in time or when a certain air pressure or amount of air is reached in the collecting hood 50 so that air can flow from the bore upwards in a controlled manner through the exhaust air line 62.

(12) To reliably prevent the leakage of air from around the collecting hood 50 an inflatable annular sealing 58 is preferably provided on an external circumference of a cylindrical section of the collecting hood 50. The inflatable annular sealing 58 is supplied with pressurized air via a feed 57 which is designed in the illustrated embodiment as simple through-openings to the air accumulation space 52. A pressure increase in the air accumulation space 52 results in a corresponding tight inflation of the annular sealing 58. Alternatively or additionally, a feeding of pressurized air can also be provided from outside so that the inflatable annular sealing 58 can be actuated at any point in time by means of a control.

(13) Basically, by way of the annular sealing 58 the entire lower region of the bore underneath the collecting hood 50 can serve as an air accumulation space 52. To enlarge this air accumulation space 52 the collecting hood 50 can be adjusted vertically along the guide section 41 of the drill rod 40, as illustrated graphically in FIG. 3. Adjustment can take place by a non-depicted adjustment means, e.g. by means of an adjustment cylinder, or automatically during operation by the rising and accumulated air in the collecting hood 50.