Twist drill for drilling having a replaceable drill tip, and a replaceable drill tip for use in a twist drill

Abstract

A twist drill, having a replaceable drill tip, comprising a drill bit shaft ( 1 ), a cutting insert ( 2 ) which is detachably fixed thereto and which forms the tip area of the twist drill, and comprises a flute ( 3 ) that continues into the cutting insert ( 2 ). The cutting insert rests, with a bearing surface ( 6 ) extending orthogonal to the center longitudinal axis ( 8 ) of the drill bit, on the face ( 7 ) of the drill bit shaft ( 1 ) and extends with a fixing stud ( 9 ), which centrally protrudes from the bearing surface ( 6 ), into a receiving recess ( 10 ) which is configured complementary thereto and which is provided in the face ( 7 ) of the drill bit shaft ( 1 ). At least one peripheral section ( 13 ) of the fixing stud ( 9 ) comprises a first longitudinal section ( 15 ) that, with a screw surface ( 16 ) which points away from the drill bit shaft ( 1 ), which slopes upward to the drill bit tip ( 5 ) in a direction of rotation of the drill bit, and which interacts with an opposite surface ( 19 ) on the inner wall ( 14 ) of the receiving recess ( 10 ), merges into a second longitudinal section ( 17 ).

What is claimed is:  
     
         1 . A twist drill comprising: 
 a shaft comprising a first end and a second end disposed opposite said first end;    said first end of said shaft comprising a shank portion being configured to be inserted into and held by a chuck;    a replaceable drilling insert being removably attached to said second end of said shaft;    said drilling insert comprising a drill tip being configured to cut an object;    at least a first chip flute and a second chip flute;    each of said first and second chip flutes comprising a first chip flute portion disposed on said shaft and a second chip flute portion disposed on said drilling insert;    said second end of said shaft comprising a recess;    said recess comprising a bottom wall and at least one side wall disposed between said bottom wall and said end face;    said drilling insert comprising a fixing stud;    said fixing stud being configured and disposed to be inserted into said recess to removably attach said drilling insert to said shaft;    said drilling insert comprising a bearing surface disposed about said fixing stud;    said shaft comprising an end face disposed about said recess;    said drilling insert bearing surface being complementary to said shaft end face and being configured and disposed to contact and rest against said shaft end face;    said fixing stud comprising at least one projection;    said at least one projection being in the shape of a portion of a screw thread and being configured to slope away from said shaft toward said drill tip in the manner of a screw thread;    said at least one projection being disposed to run substantially less than 180 degrees around a section of the perimeter of said fixing stud from said first chip flute to said second chip flute;    said at least one side wall comprising a grooved portion;    the shape of said grooved portion of said recess being complementary to the shape of said at least one projection of said fixing stud;    said grooved portion being disposed to run substantially less than 180 degrees around a section of said at least one side wall from said first chip flute to said second chip flute;    said drilling insert being configured to be rotated, upon insertion into said recess, substantially less than 180 degrees to engage said grooved portion, in a screwing motion, with said at least one projection to screw said drilling insert into said recess to tighten and sufficiently firmly seat said drilling insert in said recess to prepare the twist drill for drilling; and    said fixing stud comprising a first portion being disposed substantially transverse to said bearing surface and between said bearing surface and said at least one projection.    
     
     
         2 . A drill comprising: 
 a shaft;    a replaceable drilling insert being removably attached to said shaft;    said drilling insert comprising a drill tip being configured to cut an object;    at least one chip flute;    said at least one chip flute comprising a first chip flute portion disposed on said shaft and a second chip flute portion disposed on said drilling insert;    said shaft comprising a recess configured and disposed to receive said drilling insert and to hold said drilling insert during drilling;    said drilling insert comprising an extending portion being configured and disposed to extend into said recess of said shaft;    said extending portion comprising at least one projection;    said at least one projection being in the shape of a portion of a screw thread and being disposed to run less than 180 degrees around a section of the perimeter of said extending portion;    said recess of said shaft comprising at least one grooved portion;    said grooved portion being disposed to run less than 180 degrees around a section of the interior of said recess and being configured to be engaged by said at least one projection; and    said drilling insert and said shaft each being configured to be relatively rotated, upon insertion of said drilling insert into said recess, substantially less than 180 degrees to engage said grooved portion, in a screwing motion, with said at least one projection to screw together said drilling insert and said shaft to tighten and sufficiently firmly seat said drilling insert in said recess to prepare the drill for drilling.    
     
     
         3 . A replaceable drill insert configured to be removably attached to a drill shaft, said drill insert comprising: 
 a drill tip being configured to cut an object;    an extending portion being configured to extend into a recess in a drill shaft to removably attach said drill insert to a drill shaft and to hold said drill insert in a drill shaft during drilling;    said extending portion comprising at least one projection;    said at least one projection being in the shape of a portion of a screw thread and being disposed to run less than 360 degrees around a section of the perimeter of said extending portion;    said at least one projection being configured to project into and engage a grooved portion in a recess in a drill shaft; and    said drill insert being configured to be relatively rotated with a drill shaft, upon insertion of said drill insert into a recess in a drill shaft, less than 360 degrees to engage a grooved portion of a recess in a drill shaft with said at least one projection to screw together said drill insert and a drill shaft to tighten and sufficiently firmly seat said drill insert in a drill shaft to prepare a drill for drilling.    
     
     
         4 . A method of using a drill with a replaceable drill insert, said drill insert comprising: a drill tip being configured to cut an object; an extending portion being configured to extend into a recess in a drill shaft to removably attach said drill insert to a drill shaft and to hold said drill insert in a drill shaft during drilling; said extending portion comprising at least one projection; said at least one projection being in the shape of a portion of a screw thread and being disposed to run less than 360 degrees around a section of the perimeter of said extending portion; said at least one projection being configured to project into and engage a grooved portion in a recess in a drill shaft; and said drill insert being configured to be relatively rotated with a drill shaft, upon insertion of said drill insert into a recess in a drill shaft, less than 360 degrees to engage a grooved portion of a recess in a drill shaft with said at least one projection to screw together said drill insert and a drill shaft to tighten and sufficiently firmly seat said drill insert in a drill shaft to prepare a drill for drilling; said method comprising the steps of: 
 inserting said drill insert into a recess in a drill shaft;    aligning said at least one projection with a grooved portion in a recess in a drill shaft;    relatively rotating said drill insert and a drill shaft less than 180 degrees to engage a grooved portion of the drill shaft with said at least one projection to screw together said drill insert and the drill shaft to tighten and sufficiently firmly seat said drill insert in the drill shaft to prepare a drill for drilling;    removing said drill insert from a drill shaft by unscrewing said drill insert upon said drill insert being substantially worn as a result of drilling;    inserting a new drill insert into a recess in a drill shaft;    aligning at least one projection of said new drill insert with a grooved portion in a recess in a drill shaft; and    relatively rotating said new drill insert and a drill shaft less than 180 degrees to engage a grooved portion of the drill shaft with said at least one projection of said new drill insert to screw together said new drill insert and the drill shaft to tighten and sufficiently firmly seat said new drill insert in the drill shaft to prepare a drill for drilling.    
     
     
         5 . Drill bit with a drill bit shaft (1) and a cutting insert that forms the tip area of the drill bit and is detachable fixed to the drill bit shaft, and at least one chip flute (3) that is located in the drill bit shaft (1) and extends into the cutting insert (2), whereby the cutting insert is in contact with a bearing surface (6) on the face (7) of the frill shaft (1) and extends with a fixing stud (9) that projects centrally from the bearing surface (6) into a receiving recess (10) which is configured complementary thereto in the face (7) of the drill shaft (1), characterized by the fact that at least one peripheral segment (13) of the fixing stud (9) has a first longitudinal segment (15) which with a screw surface (16) that points away from the drill shaft (1), slopes upward in the direction of rotation (18) of the drill bit toward the drill bit tip (5) and interacts with an opposite surface (19) on the inner wall (14) of the receiving recess (10), merges into a second longitudinal section (17).  
     
     
         6 . Drill bit as claimed in  claim 5 , characterized by the fact that the second longitudinal segment (17) tapers toward its free end.  
     
     
         7 . Drill bit as claimed in  claim 6 , characterized by a first stud segment (22) forming the free end with a cylindrical peripheral surface, and a second segment (21) that has a conical peripheral surface and extends to the screw surface (16).  
     
     
         8 . Drill bit as claimed in  claim 5 , characterized by a rotation stop (25) that projects from the face (7) of the drill shaft (1) and projects into an essentially complementary shaped recess in the bearing surface (6) of the cutting insert (2).  
     
     
         9 . Drill bit as claimed in  claim 6 , characterized by a rotation stop (25) that projects from the face (7) of the drill shaft (1) and projects into an essentially complementary shaped recess in the bearing surface (6) of the cutting insert (2).  
     
     
         10 . Drill bit as claimed in  claim 7 , characterized by a rotation stop (25) that projects from the face (7) of the drill shaft (1) and projects into an essentially complementary shaped recess in the bearing surface (6) of the cutting insert (2).  
     
     
         11 . Drill bit as claimed in  claim 5 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         12 . Drill bit as claimed in  claim 6 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         13 . Drill bit as claimed in  claim 7 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         14 . Drill bit as claimed in  claim 8 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         15 . Drill bit as claimed in  claim 9 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         16 . Drill bit as claimed in  claim 10 , characterized by the fact that the screw surface (16) forms an angle (α) of 90° to 45° with the longitudinal axis (8) of the drill bit.  
     
     
         17 . Drill bit as claimed in  claim 11 , characterized by an angle (α) of 60°.  
     
     
         18 . Drill bit as claimed in  claim 12 , characterized by an angle (α) of 60°.  
     
     
         19 . Drill bit as claimed in  claim 13 , characterized by an angle (α) of 60°.  
     
     
         20 . Drill bit as claimed in  claim 16 , characterized by an angle (α) of 60°.