Rock drill

Abstract

A rock drill ( 1 ) with a helical thread ( 2 ) and a hard material insert ( 3, 9 ) in the drilling head, form a radically outer guiding surface ( 6 ), with the guiding edge ( 6 ) forming an acute angle (α) with the direction of the tool axis (A).

What is claimed is:  
     
         1 . A rock drill having a shaft with an axis (A), said shaft having a drilling head end with at least one helical thread ( 2 ) extending from said drilling head end, at least one hard material insert ( 3 ,  9 ) mounted on said drilling head end and designed for rotating and axially striking stresses, said insert ( 3 ,  9 ) having at least one guiding surface ( 6 ) at a radially outer peripheral surface of said drilling head end and said guiding surface ( 6 ) forms an acute angle with said shaft axis.  
     
     
         2 . A rock drill, as set forth in  claim 1 , wherein said hard material insert ( 3 ,  9 ) is fastened only on a surface ( 8 ) facing one of opposite to a drilling direction of said rock drill and opposite to and extending perpendicularly to the drilling direction.  
     
     
         3 . A rock drill, a set forth in  claim 2 , wherein said guiding surface ( 6 ) smoothly continues said helical thread ( 2 ).  
     
     
         4 . A rock drill, as set forth in  claim 3 , wherein said hard material insert ( 3 ,  9 ) is formed as a hard material head ( 3 ) with a drilling end facing in the drilling direction and a trailing end secured to said shaft.  
     
     
         5 . A rock drill, as set forth in  claim 3 , wherein said hard material insert is formed as a hard material plate ( 9 ).  
     
     
         6 . A rock drill, as set forth in  claim 5 , wherein said hard material plate ( 9 ) is fastening only to said drilling head end on a surface ( 8 ) facing opposite to the drilling direction.  
     
     
         7 . A rock drill, as set forth in  claim 6 , wherein said hard material plate ( 9 ) has a cutting surface ( 11 ) facing in the drilling direction and forming a smooth transition with an end surface of said helical thread at said drilling head end and facing in the drilling direction.