DTH-hammer drilling device and overburden drilling method

Abstract

The invention relates to a DTH-hammer drilling device, comprising a down-the-hole- (DTH-) hammer ( 6 ) with a percussion drill bit ( 9 ), a drill pipe ( 2 ) with a waste conduit for the cuttings and at least one supply conduit for the flushing medium and a flushing medium supply device, wherein a seal ( 18 ) for sealing the borehole against the borehole opening is provided in a fixed distance from the drilling head ( 6 ), or wherein a casing tube ( 12 ) is connected to the drill bit ( 9 ). The invention further relates to an overburden drilling method, comprising rotating a drill bit ( 9 ), supplying an energy transfer medium through a drill pipe ( 2 ) to the rotating drill bit ( 9 ) for transmitting a percussive action thereonto, dragging a casing tube ( 12 ) along with the drill bit ( 9 ) and flushing away cuttings through the drill pipe ( 2 ).

1 . A DTH-hammer drilling device, comprising:
 a down-the-hole- (DTH-) drilling head with a percussion drill bit; and   a drill pipe with a waste conduit for cuttings and at least one supply conduit for a flushing medium,   wherein a seal is provided at a fixed distance from the drilling head for sealing the DTH-hammer drilling device against the borehole opening.   
   
   
       2 . The DTH-hammer drilling device according to  claim 1 , further comprising a casing tube rotatably connected to the percussion drill bit. 
   
   
       3 . A DTH-hammer drilling device, comprising:
 a down-the-hole- (DTH-) drilling head with a percussion drill bit; and   a drill pipe with a waste conduit for the cuttings and at least one supply conduit for flushing medium,   further comprising a casing tube connected to the percussion drill bit.   
   
   
       4 . The DTH-hammer drilling device according to  claim 3 , further comprising a seal for sealing the DTH-hammer drilling device against the borehole opening. 
   
   
       5 . The DTH-hammer drilling device according to  claim 2 , further comprising a hammer, a casing tube and a sleeve tube arranged between the hammer and the casing tube. 
   
   
       6 . The DTH-hammer drilling device according to  claim 5 , wherein the sleeve tube is closed below an entrance of the waste conduit. 
   
   
       7 . A DTH-hammer drilling device, comprising; a down-the-hole- (DTH-) drilling head with a percussion drill bit; a drill pipe with a waste conduit for the cuttings and at least one supply conduit for a flushing medium; a hammer and a sleeve tube arranged around the hammer and closed below an entrance of the waste conduit. 
   
   
       8 . The DTH-hammer drilling device according to  claim 7 , further comprising a casing tube connected to the drill bit. 
   
   
       9 . The DTH-hammer drilling device according to  claim 8 , wherein the casing tube and the sleeve tube have circular-cylindrical shape. 
   
   
       10 . The DTH-hammer drilling device according to  claim 9 , wherein the casing tube and the sleeve tube are concentrically arranged. 
   
   
       11 . The DTH-hammer drilling device according to  claim 10 , wherein an outer diameter A of the sleeve tube, an n-fold inner diameter n·B of a circular-cylindrical waste conduit, and an inner diameter of the casing tube fulfill the condition that a triangle with sides A, n·B and C is right-angled or acute-angled, wherein 1.5<n<4. 
   
   
       12 . The DTH-hammer drilling device according to  claim 1 , further comprising a flushing medium supply device. 
   
   
       13 . The DTH-hammer drilling device according to  claim 1 , wherein, in a region of the hammer, a free sectional area around the hammer is at most ten times as large, and at least as large as a free cross sectional area of the waste conduit. 
   
   
       14 . The DTH-hammer drilling device according to  claim 13 , wherein the free cross sectional area around the hammer is at least four tines as large as the free cross sectional area of the waste conduit. 
   
   
       15 . The DTH-hammer drilling device according to  claim 1 , wherein the waste conduit is surrounded by the at least one supply conduit. 
   
   
       16 . The DTH-hammer drilling device according to  claim 1 , wherein the seal comprises two to five spaced apart resilient disks. 
   
   
       17 . The DTH-hammer drilling device according to  claim 16 , wherein said rubber disks are separated by at least one of less-resilient and plastic disks. 
   
   
       18 . The DTH-hammer drilling device according to  claim 17 , wherein a diameter of the plastic disks is less than a diameter of the rubber disks. 
   
   
       19 . The DTH-hammer drilling device according to  claim 16 , wherein the disks are arranged on a mounting ring rotatably arranged around the drill pipe. 
   
   
       20 . An overburden drilling method, comprising;
 rotating a drill bit;   supplying an energy transfer medium through a drill pipe to the rotating drill bit for transmitting a percussive action thereonto;   dragging a casing tube along with the drill bit; and   flushing away cuttings through a waste conduit of the drill pipe   
   
   
       21 . The drilling method according to  claim 20 , further comprising compressing air for providing the energy transfer medium. 
   
   
       22 . The drilling method according to  claim 20 , wherein the flushing away of the cuttings is effected at least partly by the energy transfer medium after its acting on the drill bit. 
   
   
       23 . The drilling method according to  claim 20 , wherein the cuttings are lifted through the drill pipe with a speed of at least 50 m/s. 
   
   
       24 . The drilling method according to  claim 20 , further comprising arranging a sleeve tube around a hammer, an flushing away the cuttings around the sleeve tube and then into the waste conduit. 
   
   
       25 . The drilling method according to  claim 24 , wherein a first drilling section is carried out with the sleeve tube arranged between the hammer and an easing tube for drilling a larger diameter first borehole section, and a second drilling section is carried out without the sleeve tube for drilling a smaller diameter second borehole section. 
   
   
       26 . A drilling method, comprising:
 rotating a drill bit;   supplying an energy transfer medium through a drill pipe to the rotating drill bit for transmitting a percussive action thereonto; and flushing away cuttings through a waste conduit of the drill pipe, wherein a first drilling section is carried out with a sleeve tube arranged around a hammer for drilling a larger diameter first borehole section, and a second drilling section is carried out without the sleeve tube for drilling a smaller diameter second borehole section, wherein in the first borehole section, cuttings are flushed away around the sleeve tube.   
   
   
       27 . The drilling method according to  claim 26 , further comprising dragging along a casing tube along with the drill bit. 
   
   
       28 . The drilling method according to  claim 20 , further comprising dragging along a packing between the casing tube and the drill pipe, or between the borehole wall and the drill pipe.