Method for laser hardening of a card wire

Abstract

A method for laser beam hardening of sections to be hardened (A) of a card wire (10) is disclosed. Thereby the card wire (10) is moved in a conveying direction through a working space (26). In the working space (26), an inert gas atmosphere is created by continuously or discontinuously introducing inert gas (G). In the working space (26), a laser beam area (27) is generated through which the sections to be hardened (A) of the card wire (10) are moved. Thereby the sections to be hardened (A) are heated. After exiting out of the laser beam area (27) the sections to be hardened (A) cool and are hardened by progressing through this temperature profile. The hardening in the inert gas atmosphere inside working space (26) avoids formation of oxide layers (scaling) and annealing colors.

1 . A method for laser hardening of a card wire ( 10 ) comprising a base section ( 11 ) and multiple teeth ( 12 ) projecting from the base section, wherein the method comprises the following steps:
 generating at least one continuous laser beam area ( 27 ) inside a working space ( 26 );   supplying an inert gas (G) into the working space ( 26 );   conveying the card wire ( 10 ) in a conveying direction (F) into the working space ( 26 ) such that a section to be hardened (A) of each tooth ( 12 ) is moved through the at least one continuous laser beam area ( 27 ), whereby at least one outer surface ( 18 ,  19 ) of each section to be hardened (A) is moved through the at least one continuous laser beam area ( 27 ), such that the section to be hardened (A) is heated; and   cooling of the section to be hardened (A).   
     
     
         2 . The method according to  claim 1 , wherein conveying the card wire ( 10 ) in the conveying direction comprises moving the card wire ( 10 ) non-stop continuously in the conveying direction (F). 
     
     
         3 . The method according to  claim 2 , wherein the card wire ( 10 ) is moved with a constant speed in the conveying direction (F). 
     
     
         4 . The method according to  claim 1 , wherein the at least one continuous laser beam area ( 27 ) has a non-circular contour having a length (x) in the conveying direction (F) and a width (y) orthogonal to the conveying direction (F) and wherein the width (y) is smaller than the length (x). 
     
     
         5 . The method according to  claim 1 , wherein the at least one continuous laser beam area ( 27 ) comprises at least one straight outer edge. 
     
     
         6 . The method according to  claim 5 , wherein the at least one straight outer edge of the at least one continuous laser beam area ( 27 ) is oriented parallel to the conveying direction (F). 
     
     
         7 . The method according to  claim 5 , wherein an intensity of laser light in the at least one continuous laser beam area ( 27 ) changes abruptly at the at least one straight outer edge of the at least one continuous laser beam area ( 27 ). 
     
     
         8 . The method according to  claim 1 , wherein the at least one continuous laser beam area ( 27 ) is generated by at least one beam forming optic ( 31 ) that forms an incident laser beam ( 30 ) into an exiting laser beam ( 32 ), whereby the exiting laser beam forms the at least one continuous laser beam area ( 27 ). 
     
     
         9 . The method according to  claim 8 , further comprising capturing at least a part of the laser light of the exiting laser beam ( 32 ) with a beam dump ( 38 ). 
     
     
         10 . The method according to  claim 9 , further comprising cooling the beam dump ( 38 ) with a cooling medium (K). 
     
     
         11 . The method according to  claim 9 , wherein the beam dump ( 38 ) comprises at least one incident surface ( 39 ) for the exiting laser beam ( 32 ) arranged inclined relative to a travel direction of the laser light passing through the at least one continuous laser beam area ( 27 ). 
     
     
         12 . The method according to  claim 1 , wherein generating at least one continuous laser beam area ( 27 ) comprises emitting a laser beam ( 29 ) from a laser beam source ( 28 ) that comprises a wavelength of 900 nm to 1100 nm. 
     
     
         13 . The method according to  claim 1 , further comprising applying the laser light in the at least one continuous laser beam area ( 27 ) on the section to be hardened (A) for an application period of 50 ms and to 70 ms. 
     
     
         14 . The method according to  claim 1 , further comprising annealing the card wire ( 10 ) prior to moving the card wire ( 10 ) into the at least one laser beam area ( 27 ). 
     
     
         15 . The method according to  claim 1 , further comprising cleaning the card wire ( 10 ) prior to moving the card wire ( 10 ) into the at least one continuous laser beam area ( 27 ). 
     
     
         16 . The method according to  claim 1 , further comprising generating a first laser beam area ( 27   a ) and a second laser beam area ( 27   b ) that is spaced apart from the first laser beam area ( 27   a ). 
     
     
         17 . The method according to  claim 16 , further comprising moving a first outer surface ( 18 ) of the section to be hardened (A) through the first laser beam area ( 27   a ) and a second outer surface ( 19 ) opposite to the first outer surface ( 18 ) of the section to be hardened (A) through the second laser beam area ( 27   b ). 
     
     
         18 . The method according to  claim 1 , further comprising measuring the heating of the section to be hardened (A).