Method and device for producing longitudinal components of metal with helical grooves, in particular spiral drill bits or screws

Abstract

A device and associated methodology for producing longitudinal components of metal with helical grooves, in particular spiral drill bits or screws, is provided. The method is suited for mass production and improves the cost effectiveness of production. The method includes providing at least one cold forming stage in which a blank is inserted in a guide mold and cold formed in a split mold with at least two movable jaws. The inner wall of the jaws includes at least one section with a contour designed as a negative of the helical grooves. By a heading tool which is movable in axial direction and which engages the free end of the blank positioned in the guide mold, the blank is pressed at least partially through the central opening of the closed split mold. Thus, helical grooves are produced during the contact with the mold contour by plastical cold forming.

1 - 27 . (canceled) 
     
     
         28 . A method for producing longitudinal components of metal with helical grooves, in particular spiral drill bits or screws, wherein, starting out from a prefabricated blank, helical grooves are produced in said blank by a deformation process, wherein at least one cold forming stage is provided in which said blank is inserted in a guide mold and is subsequently formed by a multi-stage press with a split mold with at least two movable jaws an inner wall of which comprises at least one section with a contour designed as a negative for forming helical grooves, wherein a metal wire cut to length which is formed to a blank in one or several impact extrusion or compression stages is used as a starting material for said blank, which, by a heading tool which is movable in axial direction and which engages at a free end of said blank that is positioned in said guide mold, is at least partially pressed through a central opening of said closed split mold, and that in this process, during contact with the mold contour, helical grooves are produced by plastical cold forming, and that after termination of the pressing process the split mold is opened and the cold formed blank is removed therefrom, wherein a closing force for said jaws of at least one of said cold forming molds or a force for movement of said heading tool is applied via a displaceable carriage of the multi-stage press. 
     
     
         29 . The method according to  claim 28 , wherein a shank and/or a head of said blank are preformed in further, upstream cold forming stages. 
     
     
         30 . The method according to  claim 29 , wherein, during deformation of said blank in upstream cold forming stages, said blank is at least partially guided in another guide mold and a necessary forming force is generated by an axial movement of said heading tool. 
     
     
         31 . The method according to  claim 28 , wherein said section of said blank on which said helical grooves are formed is deformed in an upstream cold forming stage. 
     
     
         32 . The method according to  claim 28 , wherein said section of said blank on which said helical grooves are formed is deformed from a round cross-sectional shape to a slot type or elliptic cross-sectional shape. 
     
     
         33 . The method according to  claim 28 , wherein said helical grooves are formed and the cross-section of said head of said blank is reduced in a cold forming stage in one method step. 
     
     
         34 . The method according to  claim 29 , wherein, in one of said upstream cold forming stages, a cross-section of a bottom part of said blank is deformed, in particular to a section without a helical groove or spiral, and that a short piece of a spiral or helix is formed on an adjacent section, wherein during cold forming the central exit opening of said split mold is closed by a counter piece. 
     
     
         35 . The method according to  claim 28 , wherein the blank comprises a section that is not subject to any further cold forming or, after completion of groove, comprises a section that is subject to such cold forming, and that is designed such that it is suited as a clamping section for a drill chuck. 
     
     
         36 . A device for producing longitudinal components of metal with helical grooves, in particular spiral drill bits or screws, comprising:
 at least one cold forming unit including a guide mold with a central opening for accommodating a blank, a split mold with at least two movable jaws that are adapted to be moved in an opening and a closing position, at least one impact extrusion or compression tool and an axially movable heading tool that is adapted to be inserted in a central opening of said guide mold,   wherein, in the closing position, said jaws are fixed by a locking force that is variable in intensity, and wherein at least one section with a contour designed as a negative for the forming of helical grooves is disposed at the inner wall of said jaws, and the cold forming unit is arranged in a multi-stage press with a stationary tool holder unit and a carrier adapted to be displaced in the direction of the tool holder unit.   
     
     
         37 . The device according to  claim 36 , wherein a lower end of said split mold comprises a section of reduced pitch for forming said head. 
     
     
         38 . The device according to  claim 36 , wherein one of said upstream cold forming units comprises a multi-piece mold having an inner contour for modifying a cross-sectional shape of said section of said blank which is to be cold formed. 
     
     
         39 . The device according to  claim 36 , wherein said split mold is in communication with an external drive unit for radial movement of said jaws in the closing and opening position. 
     
     
         40 . The device according to  claim 36 , wherein said split mold is mounted either on said tool holder unit or said carrier of a multi-stage press, and that an actuator is disposed on said carrier or on said tool holding unit via which said jaws are radially displaceable. 
     
     
         41 . The device according to  claim 36 , wherein said blank comprises a section that is subject to a further cold forming, and that said section is designed such that it is suited as a clamping section for a drill chuck. 
     
     
         42 . The device according to  claim 36 , wherein the section of said blank has a polygonal, in particular hexagonal cross-section.