Core bit for use with a core drill

Abstract

The present invention relates to a core bit ( 1 ) for a core drill in which a tube ( 20 ) is detachable relative to a coupling ( 10 ), and has a structure which allows core remaining in a tube to be removed out of an opening of the tube at a side thereof where no segment is present. The core bit further has a firm structure for fitting the tube ( 20 ) onto the coupling ( 10 ). The coupling ( 10 ) of the core bit ( 1 ) to be fitted to the core drill has an insertion part ( 11 b ), onto which the tube ( 20 ) is to be detachably fitted. On the outer side of the coupling ( 10 ), there is mounted a coupling cover ( 30 ), which covers the insertion part ( 11 b ) of the coupling ( 10 ). The provided on respective separate positions are: an anti-rotation structure for preventing the tube ( 20 ) fitted onto the insertion part ( 11 b ) from rotating relative to the insertion part ( 11 b ); and a fixing structure for preventing the tube ( 20 ) from dropping off the insertion part ( 11 b ).

1 . A core bit for a core drill which is used for boring or perforation of an object such as a concrete construction, said core bit comprising: a coupling being mounted on a rotating spindle of said core drill; and a hollow cylindrical tube being detachably fitted to said coupling, 
 wherein said tube has at an opening end thereof perforating blades,    said coupling has an insertion part onto which an other opening end of the tube is detachably fitted;    said coupling is fitted on an exterior thereof with a coupling cover, said coupling cover covering said insertion part of the coupling,    said core bit has: an anti-rotation structure for preventing the tube fitted onto the insertion part from rotating relative to the coupling; and a fixing structure for preventing the tube fitted onto the insertion part from moving in a path of fitting of the tube, and said anti-rotation structure and fixing structure are provided on separate positions from each other.    
   
   
       2 . The core bit for a core drill according to  claim 1 , wherein the coupling cover is rotatable around said rotation spindle and is fitted onto the coupling in a manner immovable in said path of fitting, 
 said fixing structure comprising: catching members provided on the coupling cover; and steps disengageably engaged with the catching members and provided on said tube,    said catching members and steps are engaged with each other when the coupling cover is rotated to a predetermined engaging position with the tube fitted onto the insertion part of the coupling.    
   
   
       3 . The core bit for a core drill according to  claim 2 , wherein the coupling is in engagement with the coupling cover or tube, and is provided with a pressure means which imparts a pressure pressing said catching members and steps, being in engagement with each other, against each other via the coupling cover and/or tube.  
   
   
       4 . The core bit for a core drill according to  claim 3 , wherein said pressure means has convex members which is brought into engagement with the coupling cover while being biased in a direction same as that of insertion of the tube, 
 said coupling cover has concave portions into which said convex members of the pressure means are disengageably engaged, and    said convex members engage into said concave portions when the coupling cover is rotated to said predetermined engaging position with the tube fitted onto the insertion part of the coupling.    
   
   
       5 . The core bit for a core drill according to  claim 1 , wherein the anti-rotation structure comprises anti-rotation pins formed either on the coupling or the tube and extending in said path of fitting, and holes formed on the other into which the pins are inserted.  
   
   
       6 . The core bit for a core drill according to  claim 1 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       7 . The core bit for a core drill according to  claim 2  wherein the anti-rotation structure comprises anti-rotation pins formed either on the coupling or the tube and extending in said path of fitting, and holes formed on the other into which the pins are inserted.  
   
   
       8 . The core bit for a core drill according to  claim 3  wherein the anti-rotation structure comprises anti-rotation pins formed either on the coupling or the tube and extending in said path of fitting, and holes formed on the other into which the pins are inserted.  
   
   
       9 . The core bit for a core drill according to  claim 4  wherein the anti-rotation structure comprises anti-rotation pins formed either on the coupling or the tube and extending in said path of fitting, and holes formed on the other into which the pins are inserted.  
   
   
       10 . The core bit for a core drill according to  claim 2 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       11 . The core bit for a core drill according to  claim 3 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       12 . The core bit for a core drill according to  claim 4 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       13 . The core bit for a core drill according to  claim 5 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       14 . The core bit for a core drill according to  claim 7 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       15 . The core bit for a core drill according to  claim 8 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.  
   
   
       16 . The core bit for a core drill according to  claim 9 , wherein the coupling has in the insertion part thereof seal packings for sealing a gap between the coupling and tube fitted onto the coupling.