Double headed drill bit for a continuous coal mining machine

Abstract

A double headed drill bit for a cutting element carried on a rotary drum member of a continuous mining machine is provided according to the invention. The drill bit is formed from a length of hardened material and includes a first tapered bit portion extending from a point located at a first end of the length of hardened material toward a mid-portion of the length of hardened material, and a second tapered bit portion extending from a point located at a second end of the length of hardened material toward the mid-portion of the length of hardened material. The drill bit is removably positioned within the central opening of an annular sleeve located in a block member mounted on the rotary drum member. One of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. Positive retention means for securing the drill bit against longitudinal movement within the annular sleeve are also provided in the form of a retaining clip which engages an annular groove at the mid-portion of the drill bit.

1 . A drill bit formed from a length of hardened material for use in connection with one or more cutting elements of a continuous coal mining machine wherein the body of each of said one or more cutting elements comprises a block member having a substantially cylindrical opening in a face thereof for receiving a shank portion of an annular sleeve having a substantially circular opening therein for receiving said drill bit, said drill bit comprising:
 a first tapered bit portion extending from a point located at a first end of said length of hardened material toward a mid-portion of said length of hardened material;   a second tapered bit portion extending from a point located at a second end of said length of hardened material toward said mid-portion of said length of hardened material; and   means for securing said drill bit within said cutting element of said continuous mining machine, said securing means being located at said mid-portion of said length of hardened material.   
     
     
         2 . The drill bit of  claim 1  wherein said securing means comprises an annular groove in the mid-portion of said length of hardened material and positive retention means associated with the cutting element to prevent longitudinal movement of the drill bit relative to a body of the cutting element. 
     
     
         3 . The drill bit of  claim 2  further comprising first and second annular collars associated with the respective first and second tapered bit portions, said first and second annular collars being adjacent to and forming the annular groove. 
     
     
         4 . The drill bit of  claim 3  wherein each of the first and second annular collars includes one or more outer cam surfaces configured to seat in and rotatably engage a surface of the cutting element. 
     
     
         5 . The drill bit of  claim 2  wherein said positive retention means comprises a retention clip which removably extends through one or more openings in the body of the cutting element and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element. 
     
     
         6 . The drill bit of  claim 5  wherein the retention clip is substantially u-shaped and includes a first leg that extends though a first opening in the body of the cutting element and a second leg that extends through a second opening in the body of the cutting element. 
     
     
         7 . (canceled) 
     
     
         8 . The drill bit of  claim 1  wherein the annular sleeve further includes a collar section that extends from the shank portion above the face of the block member such that said one or more openings in the body of the cutting element are located in the collar section of the annular sleeve. 
     
     
         9 . The drill bit of  claim 8  wherein the shank portion of the annular sleeve is securely press-fit into the block to prevent rotation thereof when in use. 
     
     
         10 . The drill bit of  claim 1  further comprising a hardened drill bit insert located in a first cavity at the first end of the drill bit and a hardened drill bit insert located in a second cavity at the second end of the drill bit. 
     
     
         11 . A cutting element carried on a rotary drum member of a continuous mining machine, said cutting element comprising:
 a block member mounted on said rotary drum member, said block member having a substantially cylindrical opening in a face thereof;   an annular sleeve having a central substantially circular opening extending through the length thereof, said annular sleeve having a shank portion positioned within the cylindrical opening of the block member and a collar member extending from the shank portion above the cylindrical opening in the block member;   a drill bit formed from a length of hardened material, said drill bit having a first tapered bit portion extending from a point located at a first end of said length of hardened material toward a mid-portion of said length of hardened material, and a second tapered bit portion extending from a point located at a second end of said length of hardened material toward said mid-portion of said length of hardened material, said drill be being removably positioned within the central opening of the annular sleeve such that one of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve; and   positive retention means for securing said drill bit against longitudinal movement within said annular sleeve.   
     
     
         12 . The cutting element for a continuous mining machine according to  claim 11 , wherein said collar portion of said annular sleeve includes one or more lateral opening extending through the collar portion, said openings extending substantially perpendicular to a longitudinal axis of the drill bit. 
     
     
         13 . The cutting element for a continuous mining machine according to  claim 12  wherein said drill bit comprises an annular groove in the mid-portion of said length of hardened material. 
     
     
         14 . The cutting element for a continuous mining machine according to  claim 13  wherein said positive retention means comprises a retention clip which removably extends through said one or more lateral openings in the collar portion of the annular sleeve and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element. 
     
     
         15 . The cutting element for a continuous mining machine according to  claim 14  wherein the retention clip is substantially u-shaped and includes a first leg that extends though a first opening in the collar portion of the annular sleeve and a second leg that extends through a second opening in the collar portion of the annular sleeve. 
     
     
         16 . The cutting element for a continuous mining machine according to  claim 11  further comprising a cylindrical end support configured to be inserted into the lower end of the sleeve. 
     
     
         17 . The cutting element for a continuous mining machine according to  claim 16  wherein the cylindrical end support has an outer surface that is configured to be rotatably received within the circular opening in the annular sleeve. 
     
     
         18 . The cutting element for a continuous mining machine according to  claim 17  wherein the outer surface of the cylindrical end support also includes an annular groove configured to removably receive a clip therein, said clip limiting the travel of the end support into the annular sleeve. 
     
     
         19 . The cutting element for a continuous mining machine according to  claim 17  wherein an inner surface of the cylindrical end support includes a large opening area defined by a first tapered section followed by a vertical wall, said first tapered section configured to engage and support the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. 
     
     
         20 . The cutting element for a continuous mining machine according to  claim 16  wherein the cylindrical end support provides a means for removal of the drill bit if the bit breaks off at the shank.