Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
  • B21C1/003—Drawing materials of special alloys so far as the composition of the alloy requires or permits special drawing methods or sequences
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B1/00—Constructional features of ropes or cables
  • D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
  • D07B1/0606—Reinforcing cords for rubber or plastic articles
  • D07B1/066—Reinforcing cords for rubber or plastic articles the wires being made from special alloy or special steel composition
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/30—Inorganic materials
  • D07B2205/3021—Metals
  • D07B2205/3025—Steel
  • D07B2205/3035—Pearlite
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2205/00—Rope or cable materials
  • D07B2205/30—Inorganic materials
  • D07B2205/3021—Metals
  • D07B2205/3025—Steel
  • D07B2205/3046—Steel characterised by the carbon content
  • D07B2205/3057—Steel characterised by the carbon content having a high carbon content, e.g. greater than 0,8 percent respectively SHT or UHT wires
• • D—TEXTILES; PAPER
  • D07—ROPES; CABLES OTHER THAN ELECTRIC
  • D07B—ROPES OR CABLES IN GENERAL
  • D07B2501/00—Application field
  • D07B2501/20—Application field related to ropes or cables
  • D07B2501/2046—Tyre cords

Definitions

• the present invention relates to a method of producing a steel wire (hereinafter, also simply referred to as “production method”), and particularly to a method of producing a steel wire in which the energy which is required for producing steel wire can be reduced.
• a steel cord composed of, for example, steel wires twisted together is employed.
• a high carbon steel wire used for this steel wire is conventionally produced by the following processes.
• Such a high carbon steel wire is made by using, as a raw material, a high carbon steel wire which has a pearlite structure by a Stelmor process having a diameter of about 5.5 mm.
• a drawing process is applied to the raw material to obtain an intermediate wire having a diameter larger than the final diameter.
• a dry drawing is generally applied, or in some cases, two drawing processes and a heat treatment therebetween are applied.
• the intermediate wire is subjected to a patenting heat treatment to obtain a heat treated wire having a fine pearlite structure.
• a brass plating process is applied followed by the heat treatment.
• the heat treated wire is subjected to a drawing as the final drawing process to obtain a steel wire having a desired final diameter and a desired tensile strength.
• a wet drawing method is generally applied as such a final drawing process.
• the tensile strength of the steel wire produced by the above process is highly influenced by the composition of the raw materials (mainly the content of carbon) and the amount of drawing in the final drawing process. That is, the higher the content of carbon and the larger the amount of drawing in the final drawing process, a steel wire having the higher tensile strength can be obtained.
• the content of carbon in a raw material generally used for the production of a wire for steel cords is 0.80 to 0.86% by mass (hereinafter, referred to as “80 C material”).
• 80 C material 0.80 to 0.86% by mass
• Df represents the final diameter of the steel wire obtained in the final drawing process
• D0 represents the diameter of the heat treated wire before the final drawing process
• ln represents natural logarithm
• Patent Documents 1 to 4 disclose a technique for increasing tensile strength by increasing the amount of final drawing by using 80 C material and by improving the final drawing conditions.
• Patent Documents 5 and 6 disclose a technique for increasing tensile strength by using a raw material whose carbon content is increased and by adjusting the amount of drawing in the pre-drawing process in which an intermediate wire is produced.
• Patent document 7 discloses a technique for increasing tensile strength by using a raw material whose carbon content is increased and by adding an alloy element such as Cr.
• Patent Documents 8 and 9 disclose a technique of producing a steel wire having the same tensile strength as in the case where 80 C material is applied by using a raw material whose carbon content is less than that of 80 C material and by increasing the amount of final drawing.
• Patent Document 1 Japanese Unexamined Patent Application Publication No. 8-132128 (Claims and the like)
• Patent Document 2 Japanese Unexamined Patent Application Publication No. 8-218282 (Claims and the like)
• Patent Document 3 Japanese Unexamined Patent Application Publication No. 10-325089 (Claims and the like)
• Patent Document 4 Japanese Unexamined Patent Application Publication No. 11-241280 (Claims and the like)
• Patent Document 5 Japanese Unexamined Patent Application Publication No. 6-136453 (Claims and the like)
• Patent Document 6 Japanese Unexamined Patent Application Publication No. 2007-111767 (Claims and the like)
• Patent Document 7 Japanese Unexamined Patent Application Publication No.
• Patent Document 8 Japanese Unexamined Patent Application Publication No. 8-260096 (Claims and the like)
• Patent Document 9 Japanese Unexamined Patent Application Publication No. 8-325964 (Claims and the like)
• an object of the present invention is to solve the problems in the above described conventional art and to provide a production method in which a steel wire having a good tensile strength can be produced with a small processing energy.
• an object of the present invention is to provide a production method in which a steel wire having a similar tensile strength as a steel wire obtained by a conventional general production method using a 80 C material can be produced with a small processing energy.
• the drawing method of the wet drawing is a method in which a wire is pulled out in a lubricating liquid by a capstan.
• the wire drawing machine requires a difference in speed between the capstan and a wire, i.e., a slip, which becomes a loss of power for production.
• the dry wire drawing machine used for the pre-drawing is a method in which the speed of one step of the capstan is controlled by one motor, a slip does not occur and a loss of power for production is small.
• the method of producing a steel wire of the present invention is a method of producing a steel wire, the method including: a pre-drawing process in which a high-carbon steel wire containing 0.90 to 1.20% by mass of carbon is subjected to a drawing to obtain an intermediate wire; a heat treatment process in which the intermediate wire is subjected to a patenting heat treatment to obtain a heat treated wire; and a final drawing process in which the heat treated wire is subjected to a drawing to obtain a steel wire, wherein the amount ⁇ f of drawing in the final drawing process which satisfies the relation represented by the following formula:
• the metal structure of the high-carbon steel wire is preferably pearlite, and further, the diameter of the steel wire obtained by the final drawing process is preferably 0.05 to 0.50 mm. Still further, in the method of producing a steel wire of the present invention, it is preferred that the tensile strength TSf of the steel wire obtained in the final drawing process, the tensile strength TS of the heat treated wire and the ⁇ f satisfy the relation represented by the following formula:
• TSf is 2700 to 3300 MPa.
• a high-carbon steel wire containing 0.90 to 1.05% by mass of carbon be subjected to a drawing to obtain an intermediate wire;
• the ⁇ f be 2.70 to 3.05; and
• the TSf be 2700 to 3200 MPa.
• the method of producing a steel wire of the present invention includes: a pre-drawing process in which a high-carbon steel wire is subjected to a drawing process to obtain an intermediate wire; a heat treatment process in which the intermediate wire is subjected to a patenting heat treatment to obtain a heat treated wire; and a final drawing process in which the heat treated wire is subjected to a drawing to obtain a steel wire.
• a high-carbon steel wire containing 0.90 to 1.20% by mass of carbon is used as a raw material, and a raw material in which an alloy element such as Cr, Ni or V is added to the high-carbon steel wire can also be used.
• the amount of carbon contained in the high-carbon steel wire is less than 0.90% by mass, the amount of processing required in the final drawing process cannot be set much low compared with the case of applying a general 80 C material, and thus the energy-saving effect is small.
• the amount of carbon contained in the high-carbon steel wire is more than 1.20% by mass, a uniform metal structure in the heat treatment process becomes hard to be obtained, and the drawability of the heat treated wire becomes poor.
• Df represents the final diameter of the steel wire obtained in the final drawing process
• D0 represents the diameter of the heat treated wire before the final drawing process
• ln represents natural logarithm
• An electric power need for the final drawing process largely accounts for the energy consumed in the production of a steel wire. For this reason, by adjusting the amount of drawing ⁇ f in the final drawing process, a steel wire having a good tensile strength can be produced with a small processing energy.
• the amount of drawing needed in the final drawing process in order to obtain the same tensile strength as that of a conventional article can be made small, thereby reducing the energy needed for the production.
• to make the amount of final drawing small is advantageous for improving the ductility of the steel wire, and accompanying effects such as improvement of productivity due to decrease of breaking of wire and improvement of the quality of steel wire can be expected.
• the metal structure of the high-carbon steel wire is pearlite. This is because the work hardening rate of the pearlite steel is larger that of martensite steel.
• the diameter of the steel wire obtained in the final drawing process be 0.05 to 0.50 mm.
• This range is a desired range of the diameter for a cord for reinforcing rubbers or a cord for ropes, and by using this range, a steel wire having a good tensile strength can be produced with a small processing energy.
• the tensile strength TSf of the steel wire obtained in the final drawing process, the tensile strength TS of the heat treated wire and the ⁇ f satisfy the relation represented by the following formula:
• the TSf is 2700 to 3300 MPa.
• the tensile strength of the steel wire is less than 2700 MPa, the strength of the steel wire for a cord for reinforcing rubbers or a cord for ropes may be insufficient, and on the other hand, when the tensile strength of the steel wire is more than 3300 MPa, it is needed that the amount of processing in the final drawing process be set large even when the carbon content is increased, and thus the energy-saving effect may be small.
• a high-carbon steel wire containing 0.90 to 1.05% by mass of carbon be subjected to a drawing to obtain an intermediate wire; the amount ⁇ f of drawing be 2.70 to 3.05; and the tensile strength of the steel wire obtained in the final drawing process be 2700 to 3200 MPa.
• the upper limit of the amount of carbon contained in the high-carbon steel wire is 1.05, it becomes easy to obtain a uniform metal structure in the heat treatment process.
• the method of producing a steel wire of the present invention can be employed for a method of producing a cord for a steel cord for reinforcing rubber articles or a cord for a wire rope.
• a high-carbon steel wire (102 C material) having a diameter of 5.5 mm and containing 1.02% by mass of carbon was subjected to a drawing to produce an intermediate wire (pre-drawing process).
• the pre-drawing process was conducted without an intermediate heat treatment.
• the obtained intermediate wire was subjected to a patenting heat treatment to produce a heat treated wire (heat treatment process, heat treatment plating).
• the heat treated wire was subjected to a drawing (final drawing process), to obtain a steel wire of Example 1 having a diameter of 0.19 mm and having a tensile strength TSf of 3000 MPa.
• the metal structure of the high-carbon steel wire used is a virtually uniform pearlite structure.
• Example 2 A steel wire of Example 2 having a diameter of 0.19 mm and having a TSf of 3000 MPa was obtained in the same manner as in Example 1 except that the production conditions shown in the Table 1 below were used.
• a steel wire of Conventional Example having a diameter of 0.19 mm and having a TSf of 3000 MPa was obtained in the same manner as in Example 1 except that the production conditions shown in the Table 1 below were used.
• a steel wire of Comparative Example 1 having a diameter of 0.19 mm and having a TSf of 3000 MPa was obtained in the same manner as in Example 1 except that the production conditions shown in the Table 1 below were used.
• a 90 C material was processed using the production conditions shown in the Conventional Example to obtain a steel wire of Comparative Example 2 having a diameter of 0.19 mm and having a TSf of 3350 MPa.
• a steel wire of Comparative Example 3 having a diameter of 0.19 mm and having a TSf of 3000 MPa was obtained in the same manner as in Example 1 except that the production conditions shown in the Table 1 below were used.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Metal Extraction Processes (AREA)
• Heat Treatment Of Steel (AREA)

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• 2010
  • 2010-03-02 JP JP2011502765A patent/JP5701744B2/ja not_active Expired - Fee Related
  • 2010-03-02 EP EP10748749.8A patent/EP2404681B1/en not_active Not-in-force
  • 2010-03-02 US US13/254,308 patent/US20110314888A1/en not_active Abandoned
  • 2010-03-02 WO PCT/JP2010/053352 patent/WO2010101154A1/ja active Application Filing
  • 2010-03-02 CN CN2010800104871A patent/CN102341194A/zh active Pending

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