EP1402965B1 - Method for manufacturing heat- treated deformed steel - Google Patents

Method for manufacturing heat- treated deformed steel Download PDF

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Publication number
EP1402965B1
EP1402965B1 EP01954408A EP01954408A EP1402965B1 EP 1402965 B1 EP1402965 B1 EP 1402965B1 EP 01954408 A EP01954408 A EP 01954408A EP 01954408 A EP01954408 A EP 01954408A EP 1402965 B1 EP1402965 B1 EP 1402965B1
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EP
European Patent Office
Prior art keywords
steel wire
hot
section
modified cross
cross
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP01954408A
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German (de)
English (en)
French (fr)
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EP1402965A4 (en
EP1402965A1 (en
Inventor
Chikaharu Sakata
Yukio Murayama
Kazuo Kinugasa
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Neturen Co Ltd
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Neturen Co Ltd
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Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F9/00—Straining wire
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B21B1/166—Rolling wire into sections or flat ribbons
    • 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
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
    • B21C37/045—Manufacture of wire or bars with particular section or properties
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/08—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with differently-directed roll axes, e.g. for the so-called "universal" rolling process
    • B21B13/10—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with differently-directed roll axes, e.g. for the so-called "universal" rolling process all axes being arranged in one plane
    • B21B13/103—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with differently-directed roll axes, e.g. for the so-called "universal" rolling process all axes being arranged in one plane for rolling bars, rods or wire
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2205/00—Particular shaped rolled products
    • B21B2205/04—Taper- or wedge-shaped profiles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B39/00—Arrangements for moving, supporting, or positioning work, or controlling its movement, combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B39/006—Pinch roll sets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B39/00—Arrangements for moving, supporting, or positioning work, or controlling its movement, combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B39/02—Feeding or supporting work; Braking or tensioning arrangements, e.g. threading arrangements
    • B21B39/08—Braking or tensioning arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/004—Heating the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0203—Cooling
    • B21B45/0209—Cooling devices, e.g. using gaseous coolants
    • B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
    • B21B45/0224—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for wire, rods, rounds, bars
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation

Definitions

  • the present invention relates to a method for producing a modified cross-section steel wire, wherein the steel wire, which has been subjected to a heat treatment, is for use in coil springs or the like and assumes, in cross section, a modified shape such as a square shape, a rectangular shape or a nearly trapezoidal shape.
  • a method according to the preamble of claim 1 is e.g. known from AT-B 396 073 .
  • a coil spring which is constructed of, for example, a modified cross-section steel wire and produced through a wire drawing process.
  • a starting material i.e., a rolled steel bar assuming a circular shape in cross section is drawn to form such a modified cross-section steel wire, as shown in Fig. 5 .
  • Such drawn steel wire is then subjected to a quenching treatment which is followed by a tempering treatment such as an oil tempering treatment and the like.
  • a tempering treatment such as an oil tempering treatment and the like.
  • the steel wire is coiled to form a coil spring, or further subjected to another process shown in Fig. 5 (b) after completion of such coiling process, in which another process the coil spring thus formed is subjected to a quenching and a tempering treatment using an electric furnace or the like.
  • a conventional method for manufacturing a coil spring requires two process steps comprising a wire drawing step for drawing a modified cross-section wire or the like and a heat treatment step including a quenching and a tempering treatment, the conventional method suffers from the large number of its necessary process steps, which makes it difficult for the conventional method to reduce manufacturing costs.
  • a starting material i.e., a steel wire assuming a circular shape in cross section
  • a quenching treatment through a heat treatment
  • the present invention is useful for production of a coil spring constructed of a high-strength steel wire. Further, the present invention is also useful for production of various types of a modified cross-section steel wire serving as a square cross-section torsion bar and the like, which has a modified cross section and must be smooth in shape.
  • the present invention provides a method with the steps according to claim 1 in combination.
  • the present invention makes it possible to draw the high alloy steels into a modified cross-section steel wire in an easy manner.
  • the quenching operation in order to improve the hot-rolled steel wire in straightness, it is preferable to quench the modified cross-section steel wire under tension immediately after completion of the hot-rolling operation of the starting material of the steel wire. Further, in order to reduce variations in dimensions of the steel wire resulted from variations in tension applied to the steel wire, it is preferable to employ any one of a pinch roll, a wire take-up reel and a capstan unit which are driven by a drive unit combined with a torque converter capable of absorbing any variations in tension of the steel wire.
  • the present invention is characterized in that : using a pinch roll, a wire take-up reel and a capstan unit which are driven by a drive unit combined with a torque converter, any variations in tension in the steel wire is absorbed by such a torque converter, so that the tension of the steel wire is maintained at a predetermined level when the steel wire is quenched.
  • a modified cross section steel having a small diameter such a small-diameter steel wire is large in variations in cross section when directly subjected to tension.
  • this problem of variations in cross section of the steel wire can be solved in the present invention by using the torque converter through which a tension is applied to such a small-diameter steel wire when the steel wire is quenched.
  • the term "drive unit combined with the torque converter” means not only a combination system constructed of the drive unit and the torque converter, but also any system for driving the steel wire through the torque converter.
  • the quenching and the tempering operation of the steel wire by performing the quenching operation which is followed by an induction heating operation.
  • the steel wire is heated to a tempering temperature thereof. After the steel wire reaches such a tempering temperature thereof, the steel wire is tempered.
  • such a tempering operation of the steel wire is continuously performed using the induction heating coil, wherein the induction heating coil is disposed in a downstream side of the quenching means or unit in a tandem manner.
  • the method of the present invention is effective in producing the modified cross-section steel wire assuming, in cross section, either a square shape, a rectangular shape or a nearly trapezoidal shape. It is possible for the method of the present invention to produce the modified cross-section steel wire in an easy manner, wherein the steel wire has been quenched and has a tensile strength of equal to or more than 1600 N/mm 2 .
  • An apparatus of the present invention for producing a modified cross-section steel wire having been heat-treated comprises: an in-line pre-heating means or unit for heating a starting material of the modified cross-section steel wire to a hot-rolling temperature using an induction heating means or unit or directly using a resistance heating means or unit; a hot-rolling means or unit for hot-rolling the starting material into a modified cross-sectional steel wire having a predetermined cross section; a quenching means or unit for quenching the thus hot-rolled modified cross-section steel wire under tension applied thereto; and, a tension applying means or unit for applying a tension to the modified cross-section steel wire thus hot-rolled, wherein all the means or units are arranged in tandem.
  • the hot-rolling means or unit is constructed of a four-side hot-rolling mill.
  • the tension applyingmeans or unit is constructed of either a pinch roll, a wire take-up reel or a capstan unit driven by a drive unit provided with a torque converter for absorbing variations in tension appearing in the steel wire.
  • Disposed in a downstream side of the quenching/cooling means or unit in tandem is an post-heating means or unit for heating the steel wire to a tempering temperature, which makes it possible for the apparatus of the present invention to continuously perform the quenching operation and the tempering operation of the steel wire.
  • Fig. 1 is a view illustrating the concept of the present invention in construction with the use of an embodiment of an apparatus of the present invention for producing the modified cross-section steel wire having been heat-treated.
  • Fig. 2 is a view illustrating in configuration the cross section of an embodiment of the modified cross-section steel wire having been heat-treated, wherein the steel wire is used in the embodiment of such an apparatus of the present invention.
  • Fig. 3 is a view illustrating, in configuration, each of rolls of the four-side hot-rolling mill (i.e., a hot-rolling means or unit) used in the hot-rolling operation of the steel wire according to the present invention.
  • Fig. 4 is a flow diagram illustrating the process steps required in producing the modified cross-section steel wire having been heat-treated according to the embodiment of the present invention.
  • Fig. 1 arranged in tandem from the left (i.e., an upstream side of Fig. 1 ) to the right (i.e., a downstream side of Fig. 1 ) are: an in-line pre-heating coil (i.e., an in-line pre-heating means or unit) 6; a four-side hot-rolling mill (i.e., a four-side hot-rolling means or unit) 7; a water-cooled jacket (i.e., a quenching/cooling means or unit) 8; a pinch roll (i.e., a tension applying means or unit) 9; and, an in-line post-heating coil (i.e., an in-line post-heating means of unit) 10; and, a wire take-up reel 11.
  • the pinch roll 9 is driven by a motor 9a which is combined with a torque converter provided with a speed-reduction unit.
  • a modified cross-section steel wire W2 of an embodiment of the present invention has been heat-treated and assumes a nearly trapezoidal shape in cross section.
  • Used in a hot-rolling operation of such a modified cross-section steel wire W2 is the four-side hot-rolling mill 7.
  • the four-side hot-rolling mill 7 is constructed of: a pair of upper and lower horizontal rolls 1, 1 adjacent to upper and lower non-parallel sides of the nearly trapezoidal cross section of the steel wire W2; and, a pair of left and right vertical rolls 2, 2 adjacent to upper and lower parallel sides of the nearly trapezoidal cross section of the steel wire W2.
  • a method for producing the modified cross-section steel wire W2 will be described.
  • a piece of rolled steel having a predetermined diameter is descaled.
  • the piece of rolled steel thus descaled is drawn into a starting material W1 of the steel wire W2 while keeping its round shape in cross section.
  • Such a starting material W2 is then delivered to the in-hot-rolling process heating coil 6 from a pay-off reel (not shown).
  • the starting material W1 is induction-heated using the in-hot-rolling process heating coil 6, and then delivered to the four-side hot-rolling mill 7, in which the starting material W1 is hot-rolled into the steel wire W2 assuming a nearly trapezoidal shape in cross section, as shown in Fig. 2 .
  • the steel wire W2 thus hot-rolled is quenched using the water-cooled jacket 8.
  • the pinch roll 9 is rotatably driven at a speed slightly higher than a traveling speed of the modified cross-section steel wire W2 measured in a downstream side of the hot-rolling mill 7, the steel wire W2 is delivered from the mill 7 under tension applied by the pinch roll 9 to the following quenching stage in which the quenching operation of the steel wire W2 is performed.
  • the pinch roll 9 is driven by the motor 9a combined with the torque converter provided with the speed-reduction unit, there is no fear that the steel wire W2 is exposed to excessive tension. Consequently, it is possible to prevent the steel wire W2 from varying in dimension.
  • the steel wire W2 thus quenched is heated to a tempering temperature using the in-tempering operation heating coil 10 and then tempered. Subsequent to this tempering operation, the steel wire W2 thus tempered is taken up by the wire take-up reel 11. Then, in the production of a coil spring, the modified cross-section steel wire thus taken up by the reel 11 is coiled to assume a predetermined shape.
  • a conventional method is constructed of two steps comprising the steps of: drawing a starting material into a modified cross-section steel wire; and, quenching and tempering the steel wire thus drawn.
  • both the step of drawing the starting material into the modified cross-section steel wire and the step of quenching and tempering the steel wire described in the conventional method are performed in a single step of the method of the present invention.
  • the steel wire is subjected to a tension applied by the pinch roll, it is possible to replace the pinch roll with a capstan unit. Further, it is also possible to apply a tension to the steel wire by means of the wire take-up reel. In case that the tension is applied to the steel wire by means of the capstan unit and/or the wire take-up reel, a motor combined with a torque converter is used to drive the capstan unit and/or the wire take-up reel.
  • in-line heating performed in the hot-rolling process it is possible to realize such in-line heating through induction heating and/or direct resistance heating.
  • Fig. 6 shows the chemical composition of the example 1 of the steel wire W2 having been rot-rolled.
  • Fig. 7 is a Table, which illustrates the particulars of the modified cross-section steel wire W2, and, more particularly illustrates the relationship between: dimensions in cross section of the modified cross-section steel wire W2 of the example 1 which has been hot-rolled and assumes such a nearly trapezoidal shape in cross section; and, a diameter of the corresponding starting material W1 of the steel wire W2.
  • a so-called "reduction of area”, i.e., the percentage of decrease in cross sectional area of the drawn bar or wire was equal to approximately 0.9.
  • Each of a plurality of the steel wires W2 each assuming a nearly trapezoidal shape but varying in dimension was subsequently subjected to a quenching and a tempering operation under tension.
  • a quenching operation performed under tension according to the conventional method failed to produce a product constant in cross section since these small-diameter steel wires W2 were large in variations in cross sectional dimension.
  • L-60 type Of a plurality of products W2 shown in Fig. 7 , one of an L-60 type was employed as an example 1, which will be described hereinbelow.
  • the product of the L-60 type assumed a nearly trapezoidal shape in cross section such as one shown in Fig. 2 , wherein the shape had a height of 14.40 mm, a length in lower side of 7.10 mm, and a length in upper side of 4.70 mm.
  • a round bar having a diameter of 10.80 mm was used as the starting material W1 of the steel wire W2, which had been hot-rolled and assumed the above shape in cross section.
  • a so-called "reduction of area”, i.e., the percentage of decrease in cross-sectional area of the round bar or stating material W1 of the steel wire W2 during its hot-rolling operation was 0.9059.
  • variations in dimension in cross section of the modified cross-section steel wire W2 having been heat-treated was within a range of a value of equal to or less than 0.05 mm, which makes it possible to obtain the heat-treated modified cross-section steel wire W2 excellent in precision.
  • the heat treatment of the steel wire W2 was conducted under the following conditions: namely, the round bar or starting material W1 was heated up to its rolling temperature in a period of 7 seconds; and, the steel wire W2 was delivered from an exit side of the apparatus of the present invention at a traveling speed of 100 mm/sec. As shown in Fig.
  • a plurality of temperatures at which the individual heat treatments were conducted in the example 1 were measured at a plurality of positions comprising: an exit side 1 of the in-line pre-heating coil 6; a soaking position, i.e., a downstream side 2 of the in-line pre-heating coil 6, in which side 2 the starting material W1 thus heated was stabilized in temperature as a whole; an inlet side 3 of the hot-rolling mill 7; an exit side 4 of the hot-rolling mill 7; an inlet side 5 of the water-cooled jacket 8; an, an exit side 6 of the in-line post-heating coil 10.
  • Fig. 8 shows temperatures measured in the above positions of the apparatus of the present invention.
  • the round bar or starting material w1 of the steel wire w2 was heated to a temperature of approximately 1024°C which is equal to or more than the Ac3 point by using the in-line pre-heating coil 6 for heating the round bar w1 prior to its hot-rolling operation.
  • the round bar W1 had its atoms rearranged into a so-called " ⁇ (gamma)" structure.
  • the round bar W1 was hot-rolled into the modified cross-section steel wire W2 at a temperature of equal to or more than the Ar1 point ranging from 850°C to 700°C.
  • the steel wire W2 was quenched from a temperature of 740°C, which is equal to or more than the Ar1 point. This made it possible for the present invention to obtain the steel wire W2 having a fine structure of martensite excellent in strength.
  • the thus obtained steel wire W2 was heated again up to a tempering temperature of approximately 500°C and then tempered.
  • Fig. 9 shows the mechanical properties of the modified cross-section steel wire W2 having been heat-treated in the example 1.
  • the modified cross-section steel wire W2 of the L-60 type having been heat-treated under the above conditions had a large tensile strength of equal to or more than 1600 N/mm 2 and a large elongating rate of equal to or more than 10 %.
  • the modified cross-section steel wire W2 thus heat-treated was excellent in straightness and free from any small-radius bend. Consequently, in this example 1, the modified cross-section steel wire W2 thus heat-treated was formed into a coil spring.
  • a conventional type of the modified cross-section steel wire is formed into a coil spring or product, its product defective rate often reaches a value of 10%.
  • the modified cross-section steel wire W2 thus heat-treated according to the present invention and formed into a coil spring had a product defective rate of substantially 0 %.
  • any one of them was excellent in accuracy in dimension since they varied in cross-sectional dimension within a range of equal to or less than 0.05 mm.
  • the mechanical properties of the other types of the steel wires W2 are also shown in Fig. 7 , as an example.
  • the other types of the steel wires W2 were also excellent in each of straightness, tensile strength and elongation rate, as is in the example 1.
  • the round bar W1 was hot-rolled into the modified cross-section steel wire W2 and further formed into the coil spring, which was estimated and confirmed in effect of the present invention. Further, it is possible to apply the present invention to the steel wire W2 having, in cross section, not only the nearly trapezoidal shape but also other shapes such as a square shape or a rectangular shape in cross section of the steel wire W2.
  • the present invention is also applicable to not only the coil spring, but also other types of wire products such as a torsion bar and like linear products since the steel wire W2 of the present invention is excellent in straightness, which permits the method of the present invention to reduce the number of necessary process steps of the method of the present invention for producing such linear products each constructed of the modified cross-section steel wire W2 having been heat-treated, so that the production yield in the method of the present invention can be improved greatly. It is also possible to apply the present invention to various application fields other than the wire springs.
  • the method of the present invention for producing the modified cross-section steel wire W2 having been heat-treated it is possible to rapidly heat each of the round bar W1 and the steel wire W2 to a predetermined temperature in a very short period of time by using induction heating and the like. Consequently, it is possible for the method of the present invention to avoid occurrence of a problem of decarbonization which often occurs in heating in an ordinary furnace and the like. Further, in the method of the present invention, since the hot-rolled steel wire W2 of the present invention is quenched immediately after completion of its hot-rolling operation, it is possible to produce the hot-rolled modified cross-section steel wire W2 through a single process step. The above quenching operation is followed by a rapid heating and a tempering process step, which makes it possible to produce the modified cross-section steel wire W2 excellent in strength.
  • the round bar W1 is rapidly heated to a tempering temperature of equal to or more than the Ac3 point; the thus heated round bar W1 is then hot-rolled into the modified cross-section steel wire W2 at a rolling temperature of equal to or more than the Ar3 point; immediately after completion of such hot-rolling operation, the thus hot-rolled steel wire W2 is directly quenched at a temperature of equal to or more than the Ar1 point by using the quenching/cooling means or unit 8, so that the steel wire W2 having a tensile strength of equal to or more than 1600 N/mm 2 is produced.
  • the in-line post-heating means or unit 10 for heating the thus quenched steel wire W2 to a tempering temperature is disposed in a downstream side of the quenching/cooling means or unit 8 in tandem, which makes it possible to have the quenching and the tempering operation conducted in a continuous manner in the method of the present invention.
  • the round bar W2 is hot-rolled into the modified cross-section steel wire W2 using the hot-rolling mill 7, it is possible to reduce the number of surface defects of the product such as a scratch on the surface of the product and like defects, which makes it possible to produce the product or modified cross-section steel wire W2 excellent in smoothness in surface.
  • a product produced through a conventional cold-drawing process is poor in smoothness in surface.
  • the method of the present invention to produce a product made of high alloy steel which is difficult to be cold-drawn through the conventional process.
  • the modified cross-section steel wire W2 of the present invention having been heat-treated is free from any defect such as a wave, a twist and/or a slight or small-radius bend in shape, and therefore excellent in straightness in shape.
  • the tension is applied to the steel wire W2 in the quenching process by means of the pinch roll 9 and/or the wire-take-up reel and/or the capstan unit, any variation in tension does not appear in the steel wire W2. Therefore, the modified cross-section steel wire or product of the present invention is substantially free from any variation in its cross-sectional dimension, This is one of characterized features of the present invention.
  • the effect of the present invention is large particularly as to one of the modified cross-section steel wires W2, which one has a small diameter. Due to this, an effective quenching process for quenching the small-diameter ones of the modified cross-section steel wires W2 is realized by the method of the present invention. In contrast with this, such an effective quenching process is not realized in the prior art.
  • the pre-heating of the round bar W1 is conducted by induction heating, it is also possible for the method of the present invention to employ any other heating process such as a direct resistance heating process and the like. It is also possible to employ both the induction heating and the direct resistance heating process at the same time. Further, though a single stand of the four-side hot-rolling mill 7 is employed in the above embodiment of the method of the present invention, it is also possible for the method of the present invention to employ two or more stands of the hot-rolling mills 7.
  • modified cross-section steel wire W2 having been heat-treated assumes a nearly trapezoidal shape in cross section in the embodiment of the present invention
  • steel wire W2 of the present invention it is also possible for the steel wire W2 of the present invention to assume any other shape such as a square shape, a rectangular shape, or like shape in cross section.
  • the present invention As described above, according to the modified cross-section steel wire W2 having been heat-treated and the method of the present invention, it is possible to produce the heat-treated modified cross-section steel wire W2 of the present invention excellent in both straightness and strength through a single process step. Due to this, it is possible for the present invention to produce the product or coil spring which is substantially free from any defect such as ones resulted from the small-radius bend of the steel wire W2, whichmakes it possible to have the product defective rate reduced to a level of substantially 0 %, and therefore possible to considerably reduce the manufacturing cost of the product or coil spring which is constructed of the modified cross-section steel wire W2. Particularly, the present invention is effective in production of the small-diameter modified cross-section steel wire W2 having been heat-treated. Further, it is also possible to apply the present invention to any other application field such as one of a torsion bar constructed of the modified cross-section steel wire W2.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat Treatment Of Steel (AREA)
  • Metal Rolling (AREA)
EP01954408A 2001-05-10 2001-08-01 Method for manufacturing heat- treated deformed steel Expired - Lifetime EP1402965B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2001139429 2001-05-10
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US20070131319A1 (en) * 2005-12-08 2007-06-14 Pullman Industries, Inc. Flash tempering process and apparatus
KR101075323B1 (ko) * 2009-05-19 2011-10-19 대원강업주식회사 헬리코이드 리덕션 밀을 이용한 코일 스프링 제조방법
JP6259621B2 (ja) * 2012-09-27 2018-01-10 新日鐵住金ステンレス株式会社 冷間加工性、耐食性に優れた超非磁性軟質ステンレス鋼線材及びその製造方法、鋼線、鋼線コイル並びにその製造方法
US9725780B2 (en) 2014-06-13 2017-08-08 M3 Steel Tech Modular micro mill and method of manufacturing a steel long product
KR101972456B1 (ko) * 2017-07-17 2019-04-25 홍덕산업(주) 직선 품질이 우수한 타이어 보강용 스틸코드와 단일강선 및 이의 제조방법
CN108115000A (zh) * 2018-01-04 2018-06-05 上海展屿金属科技有限公司 一种小截面高精度毛刷锚线异型材的制造方法及其装置
CN110125195B (zh) * 2019-05-17 2024-04-05 江苏胜达科技有限公司 胎圈钢丝细拉生产线及其细拉工艺
CN111705184A (zh) * 2020-08-03 2020-09-25 沈阳慧通远达冶金技术研发有限公司 一种带有凹槽的钙线加工模具装置及其使用方法
CN111730007B (zh) * 2020-08-07 2022-06-24 山东睿煜矿用材料加工有限公司 一种钢筋弯箍机的矫直装置
CN114570854A (zh) * 2020-11-30 2022-06-03 宝钢金属有限公司 一种变截面弹簧钢丝及其制造方法和装置
CN113800331A (zh) * 2021-09-22 2021-12-17 绍兴市柯桥区欣飞科技有限公司 一种收线装置
CN115213243B (zh) * 2022-07-21 2024-05-14 辽宁科技大学 一种钢坯加热装置及方法

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KR20030023601A (ko) 2003-03-19
EP1402965A4 (en) 2008-08-20
US20040060619A1 (en) 2004-04-01
TWI235768B (en) 2005-07-11
WO2002092250A1 (fr) 2002-11-21
KR100662963B1 (ko) 2006-12-28
DE60143591D1 (de) 2011-01-13
EP1402965A1 (en) 2004-03-31

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