Method for producing a strip steel knife, and strip steel knife for tools

Abstract

Method and strip steel knife from a steel strip having a bainite and decarburized surface. The steel strip has a generally rectangular cross-section, and the method includes machining a plurality of beveled surfaces in a region of a longitudinal edge of the steel strip to create at least a cutting surface defining a longitudinal cutting edge; first hardening at least a part of the cutting surface to form a first cutting edge region of the longitudinal cutting edge; smoothing the cutting surface of at least the first cutting edge region toward the longitudinal cutting edge; and at least one further hardening in the first cutting edge region to form a distal cutting edge region of the longitudinal cutting edge within the first cutting edge region having an increased material hardness with respect to the first cutting edge region located outside the distal cutting edge region.

1 . A method for producing a strip steel knife with a hardened cutting edge from a steel strip comprising bainite and having a decarburized surface, the steel strip having a generally rectangular cross-section the method comprising:
 machining a plurality of beveled surfaces in a region of a longitudinal edge of the steel strip to create at least a cutting surface defining a longitudinal cutting edge;   first hardening at least a part of the cutting surface to form a first cutting edge region of the longitudinal cutting edge;   smoothing the cutting surface of at least the first cutting edge region toward the longitudinal cutting edge; and   at least one further hardening in the first cutting edge region to form a distal cutting edge region of the longitudinal cutting edge within the first cutting edge region having an increased material hardness with respect to the first cutting edge region located outside the distal cutting edge region.   
     
     
         2 . The method according to  claim 1 , wherein the machining of the plurality of beveled surfaces comprises shaving, and
 wherein the first hardening comprises inductive hardening, of at least the first cutting edge region to a value of 550 to 700 HV.   
     
     
         3 . The method according to  claim 1 , wherein, after the first hardening, the cutting surfaces layers of at least the first cutting edge region are smoothed with roughness values Ra of 0.005 to 0.12 μm and Rz of 0.05 to 1.2 μm, and an edge radius of the longitudinal cutting edge is ≤2.5 μm, and
 wherein Ra and Rz are in accordance with ÖNORM EN ISO 4287 or ASME B46.1. 
 
     
     
         4 . The method according to  claim 1 , wherein parameters of the at least one further hardening are determined based on a geometric embodiment of the first cutting edge region and a local energy input into the smoothed cutting surface layers. 
     
     
         5 . The method according to  claim 4 , wherein the at least one further hardening produces a material hardness of over 650 HV in the distal cutting edge region proximally from the longitudinal cutting edge to a depth of up to 0.05 to 0.15 mm into the first cutting edge region. 
     
     
         6 . The method according to  claim 1 , wherein the at least one further hardening produces a material hardness of over 650 HV in the distal cutting edge region proximally from the longitudinal cutting edge to a depth of up to 0.05 to 0.15 mm into the first cutting edge region. 
     
     
         7 . A strip steel knife comprising:
 a strip steel body having, in cross section, at least partial bainitic microstructure and at least one cutting edge bevel forming a longitudinal cutting edge having a maximum radius of 2.5 μm;   a first cutting edge region of the longitudinal cutting edge includes a smoothed surface layer of the at least one longitudinal cutting edge bevel;   a distal cutting edge region, which is formed in the first cutting edge region and includes the longitudinal cutting edge, has a material hardness of at least 650 HV up to a depth of 0.05 to 0.15 mm from the longitudinal cutting edge,   wherein a material hardness outside of the distal cutting region decreases in a direction away from the longitudinal cutting edge.   
     
     
         8 . The strip steel knife according to  claim 7 , wherein the at least one cutting edge bevel comprises a plurality of cutting edge bevels having smoothed surface layers exhibiting roughness values Ra of 0.005 to 0.12 μm and Rz of 0.05 to 1.2 μm,
 wherein Ra and Rz are in accordance with ÖNORM EN ISO 4287 or ASME B46.1. 
 
     
     
         9 . The strip steel knife according to  claim 7 , wherein a surface layer comprising at least one of an oxide layer, a sliding layer or a hard material layer is formed in the distal cutting edge region. 
     
     
         10 . The strip steel knife according to  claim 7 , wherein the first cutting edge region is hardened from the distal cutting edge region to a depth of 300 μm from the longitudinal cutting edge to a hardness greater than a hardness of the strip steel body outside of the first cutting edge region. 
     
     
         11 . A tool comprising the strip steel knife according to  claim 7 , wherein the strip steel knife is configured for processing planar materials. 
     
     
         12 . The tool according to  claim 11 , wherein the planar materials to be processed comprise at least one of cardboard, corrugated cardboard or plastic films.