Heat-treated deformed steel wire and method and apparatus for manufacturing the same

Abstract

Arranged in tandem are a pre-heating unit 6 , a four-side hot-rolling mill 7 and a quenching/cooling unit 8 . A starting material W 1 is rapidly heated to a hot-rolling temperature using the unit 6 and hot-rolled into a modified cross-section steel wire W 2 assuming a predetermined shape in cross section using the mill 7 . The wire is then quenched under tension using the unit 8 immediately after its hot-rolling operation. The tension is applied to the wire by a pinch roll 9 driven by a motor 9 a , which is combined with a torque converter. Consequently, there is no variation in tension, and no variation in cross-sectional dimension in the wire. Disposed behind the unit 8 in tandem is an in-line post-heating coil 10 to realize a continuous tempering operation, so that the wire free from any small-radius bend and having been heat-treated, can be produced through a substantially single process.

1 . A modified cross-section steel wire having been heat-treated, characterized in that: a starting material of said steel wire is rapidly heated to a hot-rolling temperature in a short period of time using an induction heating means and/or directly using a resistance heating means, hot-rolled into a modified cross-section steel wire having a predetermined shape in cross section and then quenched immediately after completion of its hot-rolling operation.  
     
     
         2 . The modified cross-section steel wire having been heat-treated as set forth in  claim 1 , wherein said modified cross section steel wire assumes, in cross section, either a square shape, a rectangular shape or a nearly trapezoidal shape.  
     
     
         3 . A method for producing a modified cross-section steel wire having been heat-treated, comprising the steps of: rapidly heating a starting material of said steel wire to a hot-rolling temperature in a short period of time using an induction heating means and/or directly using a resistance heating means; hot-rolling said starting material thus heated into a modified cross-section steel wire having a predetermined shape in cross section; and, quenching said modified cross-section steel wire immediately after completion of its hot-rolling operation.  
     
     
         4 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 3 , wherein said starting material is hot-rolled using a four-side hot-rolling mill.  
     
     
         5 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 3 , wherein: said starting material of said steel wire is rapidly heated at a heating rate of equal to or more than 100° C./s to a temperature of equal to or more than the Ac3 point in a short period of time, and then hot-rolled at a temperature of equal to or more than the Ar 3  point into said modified cross-section steel wire having said predetermined shape in cross section using a hot-rolling mill; and, said modified cross section steel wire thus hot-rolled is quenched immediately after completion of its hot-rolling operation at a temperature of equal to or more than the Ar1 point using a quenching/cooling means disposed adjacent to said hot-rolling mill in a tandem manner.  
     
     
         6 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 3 , wherein said modified cross-section steel wire is quenched immediately after completion of its hot-rolling operation under tension applied to said steel wire.  
     
     
         7 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 6 , wherein said tension applied to said modified cross-section steel wire using either a pinch roll, a wire take-up reel or a capstan unit each of which serves as a drive unit, said drive unit being provided with a torque converter for absorbing variations in tension of said steel wire.  
     
     
         8 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 3 , wherein, after completion of the quenching operation of said modified cross-section steel wire, said steel wire is continuously heated to a tempering temperature using an induction heating means to perform a tempering operation of said modified cross-section steel wire.  
     
     
         9 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 8 , wherein said modified cross-section steel wire having been heat-treated has a tensile strength of equal to or more than 1600 N/mm 2 .  
     
     
         10 . The method for producing the modified cross-section steel wire having been heat-treated as set forth in any one of  claims 3  to  9 , wherein said modified cross-section steel wire having been heat-treated assumes, in cross section, either a square shape, a rectangular shape or a nearly trapezoidal shape.  
     
     
         11 . An apparatus for producing a modified cross-section steel wire having been heat-treated, comprising: an in-line pre-heating means for heating a starting material of said modified cross-section steel wire to a hot-rolling temperature using an induction heating means or directly using a resistance heating means; a hot-rolling means for hot-rolling said starting material into a modified cross-sectional steel wire having a predetermined shape in cross section; a quenching means for quenching the thus hot-rolled modified cross-section steel wire under tension applied thereto; and, a tension applying means for applying a tension to said modified cross-section steel wire thus hot-rolled, wherein all said means are arranged in a tandem manner.  
     
     
         12 . The apparatus for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 11 , wherein said hot-rolling means is constructed of a four-side hot-rolling mill.  
     
     
         13 . The apparatus for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 11 , wherein said tension applying means is constructed of either a pinch roll, a wire take-up reel or a capstan unit each driven by a drive unit provided with a torque converter for absorbing variations in tension appearing in said steel wire.  
     
     
         14 . The apparatus for producing the modified cross-section steel wire having been heat-treated as set forth in  claim 11 , wherein: disposed behind said quenching means in tandem is an in-line post-heating means for heating said steel wire to a tempering temperature.