Drilling machine having rotary tools

Abstract

A drilling machine comprising: a frame; at least one pair of rotary drilling tools having substantially the same axis of rotation; and a support assembly secured to the frame and supporting said pair of tools in rotation, said support assembly presenting an edge facing the cutting face and extending between the tools of said pair of tools, said machine further comprising: means mounted on said support assembly for creating at least one jet of liquid at very high pressure directed towards the cutting face between the action zones of said pair of tools; whereby said jet of liquid at very high pressure breaks up the ridge which forms in the cutting face between the action zones of said pair of rotary tools.

1 . A drilling machine comprising: 
 a frame;    at least one pair of rotary drilling tools having substantially the same axis of rotation;    a support assembly secured to the frame and supporting said pair of tools in rotation, said support assembly presenting an edge facing the cutting face and extending between the tools of said pair of tools; and    means mounted on said support assembly for creating at least one jet of liquid at very high pressure directed towards the cutting face between the action zones of said pair of tools; whereby said jet of liquid at very high pressure breaks up the ridge which forms in the cutting face between the action zones of said pair of rotary tools.    
     
     
         2 . A drilling machine according to  claim 1 , wherein the jet-creation means comprise at least one nozzle supplied with very high pressure liquid, and opening out into said edge of the support assembly.  
     
     
         3 . A drilling machine according to  claim 2 , wherein the supply means for supplying said nozzle comprise at least one supply channel formed in said support assembly.  
     
     
         4 . A drilling machine according to  claim 3 , including a plurality of nozzles and a plurality of supply channels.  
     
     
         5 . A drilling machine according to  claim 1 , wherein, at least over a portion of its length, said edge presents a face that is not symmetrical about the mid-plane of said support assembly, whereby said asymmetrical face exerts a bending force on the ridge formed between the action zones of said pair of tools, so as to break up said ridge.  
     
     
         6 . A drilling machine according to  claim 5 , wherein said face occupies substantially the entire width of said edge, and makes an angle lying in the range 30° to 60° relative to the drilling direction.  
     
     
         7 . A drilling machine according to  claim 5 , wherein said edge includes a plurality of asymmetrical faces.  
     
     
         8 . A drilling machine according to  claim 7 , wherein said faces are inclined relative to the drilling direction in alternating directions.  
     
     
         9 . A drilling machine according to  claim 1 , wherein the or each face is constituted by a prism-shaped part fixed to the edge of the support assembly.