JP2004025205A - Production method of soft, inexpensive wire rod for cold working and in which surface flaw is warranted over whole length and wire rod for cold working produced thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of inexpensively producing a soft wire rod of carbon steel for machine structural use, alloy steel for machine structural use and high carbon chromium bearing steel for cold working in which flaws are warranted over the whole length, and to provide a wire rod produced by the method. <P>SOLUTION: A hot rolling stock of steel for a wire rod is subjected to wire rod rolling into a bus having a dimensional tolerance of ±0.15 mm or lower and a diameter deviation difference of ≤70%. The bus is subjected to annealing treatment. The bus subjected to the annealing treatment is subjected to cold drawing at a drawing reduction of area of ≤5% with a working margin of ≥0.12 mm in a diameter in such a manner that the half angle θ of a die shown in the figure with a drawing die shape is controlled to 5 to 35°. Also, eddy current flaw detection is performed. Thus, the inexpensive wire rod for cold working having a low hardness, and in which surface flaws are warranted over the whole length is obtained. <P>COPYRIGHT: (C)2004,JPO

Description

【００２５】
【発明の効果】
以上説明したように、本発明の方法により製造した焼きなまし線材は、冷間引抜きによる硬さの上昇が３〜６ＨＲＢと小さく、表面キズを全長に亘り保証した鋼線材であり、製造工程も必要最小限に簡略化されているので製造コストも安く、本発明による線材を使用することにより、冷間加工用金型の寿命向上と冷間加工成形品の寸法精度などの向上を図ることができ、さらに成形品の表面キズの品質保証のニーズに応えることができるなど、本発明は優れた効果を奏するものである。
【図面の簡単な説明】
【図１】本発明に用いる引抜きダイスのダイス形状を示す概略断面図である。
【符号の説明】
１　ダイス
２　母線[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wire rod such as a carbon steel for a mechanical structure for cold working, an alloy steel for a mechanical structure, a high carbon chromium bearing steel, and a method for producing the same.
[0002]
[Prior art]
The wire rod used as a material for cold working is considered to have low hardness, surface scratches due to the longevity of the cold working mold, the dimensional accuracy of the cold worked product or the quality assurance of the surface flaw of the formed product. Is required over the entire length. On the other hand, there are the following three types of methods for manufacturing a wire that is a conventional material for cold working.
[0003]
(1) A slab is hot-rolled, then annealed, then cold drawn, and simultaneously subjected to overcurrent flaw detection.
[0004]
(2) After the steel slab is hot-rolled to a wire, annealing is performed if necessary, then cold drawing is performed, convection detection is simultaneously performed, further annealing and rewinding are performed. This rewinding is a cold straightening process performed to correct the bending and loosening of the wire rod caused by annealing.
[0005]
(3) After the steel slab is hot rolled, the steel is annealed if necessary, then cold drawn, further annealed, and then cold drawn, and simultaneously subjected to eddy current inspection to manufacture.
[0006]
The above conventional methods have the following problems.
(1) To ensure stable mass production of wires and quality such as surface flaws, wire rolling dimensions and cold drawing finish dimensions are determined in advance by manufacturing specifications. Usually, the final reduction in the cold drawing is performed in a diameter of 0.3 to 0.5 mm, for example, in a wire having a diameter of 10 mm or less, with a reduction in area of 6 to 17%. Since the hardness of the wire is increased by about 10 to 20 HRB by the cold drawing, the product wire is hardened accordingly. Further, with respect to a wire having a diameter of more than φ10 mm, although the reduction in area (%) is smaller than that of a wire having a small diameter, the wire is still drawn out by excessive reduction, which causes an unnecessary increase in hardness. Have been.
[0007]
(2) Although the hardness of the product wire is reduced by annealing in the final step, the wire is bent or loosened by the annealing, and a cold straightening called “rewinding” must be performed to correct this. . For this reason, the production is troublesome, and the production cost is correspondingly high.
[0008]
(3) In order to ensure stable mass production and quality such as surface flaws, wire roll finishing, intermediate drawing dimensions, and final finishing drawing dimensions are determined. Therefore, the reduction of the final cold drawing can be as small as about 0.1 to 0.2 mm in diameter, so the hardness of the wire is suppressed to 5 to 8 HRB, and the wire is soft. Costs are high.
[0009]
At present, as an approach to the above-mentioned needs for cold working wires, (1) Japanese Patent Application Laid-Open No. H11-279699 discloses an example in which cold drawing after annealing is omitted by improving rolling dimensional accuracy or the like. Japanese Patent Application Laid-Open No. 9-78128 discloses an example in which (2) the cold drawing rate after annealing is reduced by improving rolling dimensional accuracy. In addition, as a matter related to the reduction of manufacturing cost, which is one of the purports of the present invention, (3) examination of cooling conditions after hot rolling, omission of annealing before cold drawing, An example of improvement is disclosed in Japanese Patent No. 2926195, but the above (1) does not refer to the guarantee of surface flaws, and (2) shows a wire rod dimensional tolerance of ± 0.10. m is strictly limited, that is, the use of precision-rolled material is the premise of the invention, and (3) is that it does not mention the production of soft steel wire, and there is a need for improvement. .
[0010]
[Problems to be solved by the invention]
The problem to be solved by the present invention is a method for manufacturing a soft, low-cost, full-length flaw-guaranteed wire rod such as carbon steel for machine work for cold working, alloy steel for machine structure, and high carbon chromium bearing steel. And a wire manufactured by the method.
[0011]
[Means for Solving the Problems]
Means of the present invention for solving the above-mentioned problems is that, in the invention of claim 1, a hot-rolled material of a wire rod is subjected to wire rolling to generate a bus bar having a dimensional tolerance of ± 0.15 mm or less and an eccentricity difference of 70% or less. The bus bar is annealed, and then the annealed bus bar is processed with a diameter of 0.12 mm or more as a machining allowance, the drawing reduction area is set to 5% or less, and the die half angle θ of the drawing die shape is set to 5 ° to 35 °. This is a method for producing an inexpensive wire rod for cold working, which is characterized by cold drawing and overcurrent flaw detection, having low hardness and ensuring surface flaws over the entire length.
[0012]
According to the second aspect of the present invention, the steel for a wire rod has, as a steel component, C: 0.08 to 1.10%, Si: 1.5% or less, Mn: 1.5% or less, and S: 0 in mass%. It is a steel containing 100% or less, Ni: 4.0% or less, Cr: 10% or less, Mo: 1.5% or less, Cu: 2.0% or less, and the balance being Fe and unavoidable impurities. A method for producing an inexpensive wire rod for cold working, wherein the means according to claim 1 is low in hardness and surface flaws are guaranteed over the entire length.
[0013]
In the invention of claim 3, in addition to the steel component of the means of claim 2, at least one or more of V: 0.40% or less, Nb: 0.40% or less, and Ti: 0.20% or less is contained. The method according to claim 2, wherein the hardness is low and the surface flaw is guaranteed over the entire length of the wire.
[0014]
According to the invention of claim 4, in addition to the steel component of the means of claim 2, Pb: 0.30% or less, Bi: 0.20% or less, Se: 0.20% or less, Te: 0.10% or less , Ca: at least one of 200 ppm or less, according to the method of claim 2, wherein the hardness is low and surface flaws are guaranteed over the entire length of the inexpensive wire rod for cold working. is there.
[0015]
In the invention of claim 5, in addition to the steel component of the means of claim 3, Pb: 0.30% or less, Bi: 0.20% or less, Se: 0.20% or less, Te: 0.10% or less , Ca: at least one of 200 ppm or less, according to the method of claim 3, characterized in that the hardness is low and surface flaws are guaranteed over the entire length of the inexpensive wire rod for cold working. is there.
[0016]
According to a sixth aspect of the present invention, there is provided a hard steel made of carbon steel for machine structure, alloy steel for machine structure, or high carbon chromium bearing steel manufactured by the method of any one of the first to fifth aspects. It is an inexpensive wire for cold working that has a low surface and guarantees surface flaws over the entire length.
[0017]
Incidentally, in the manufacturing process of the wire rod according to the first aspect of the present invention, the conventional preparation processing steps such as pickling, shot blasting, coating treatment, and deoxidizing treatment are not directly related to the essence of the present invention. Although omitted, a preparatory processing step is performed as necessary.
[0018]
The steel for wire rod of the above-mentioned steel component of the means of the present invention is made of carbon steel for machine structure, alloy steel for machine structure, or high carbon chromium bearing steel.
In the present invention, the drawing reduction area ratio is defined as [1− (drawing finished dimension / drawing bus bar dimension) ² ] × 100 (%), where the bus bar dimension is defined as (maximum value of diameter in the same cross section + The minimum value of the diameter) / 2), and the die half angle θ of the drawing die shape is as shown in FIG.
[0019]
The point of the above-described means of the present invention is that the drawing bus does not require a dimensional tolerance of precision rolled material level of ± 0.10 mm as a drawing bus, and the condition of the above-described means of the present invention is based on the actual size of the bus before drawing. By performing the drawing using a drawing die that satisfies the above condition, the drawing reduction area ratio can be reduced as compared with the conventional method. The point of the dimensional tolerance of the drawing bus is greatly different from the conventional technology. As a result, the obtained wire for cold working is softer than the conventional wire, the quality of surface flaws is guaranteed over the entire length, and it is inexpensive.
[0020]
In the manufacturing method of the present invention, various conditions at the time of wire rolling, annealing conditions, dimensional tolerances of the drawing dies, and the like do not require any special changes as long as they satisfy the conventional specifications of each user.
[0021]
By the way, in the conventional wire rod manufacturing method, the dimensions of the bus bar and the drawing dies are determined in advance according to the manufacturing specifications, etc., in view of the dimensional change depending on the manufacturing lot.As a result, the reduction of the final cold drawing is large. Therefore, as described in (1) of the problem of the conventional technique, the hardness of the manufactured product wire becomes extra hard about 10 to 20 HRB, and the wire having a size exceeding φ10 mm has a small diameter. Although the area reduction rate is smaller than that, the steel sheet is still drawn out by excessive reduction, so that an unnecessary increase in hardness is caused.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described through the following examples. Table 1 shows the JIS SUJ2 high carbon chromium bearing steel after annealing and cold drawn finished product φ8.6 ± 0.10.
[0023]
【Example】
No. 1 in Table 1. The development methods of Nos. 1 to 3 are based on the embodiment of the present invention. Comparative Examples 4 to 7 do not satisfy the conditions of the present invention. 8 to 9 are based on the conventional method. The development method of the present invention can suppress the increase in hardness due to drawing to a range of 3 to 6 HRB, particularly in cold drawing after annealing, and at the same time, perform overcurrent flaw detection to soften surface scratches over the entire length. The manufacturing process of the assured wire rod was simplified to the minimum necessary, so that the manufacturing cost was low and the wire could be manufactured.
[0024]
[Table 1]

[0025]
【The invention's effect】
As described above, the annealed wire manufactured by the method of the present invention is a steel wire in which the increase in hardness due to cold drawing is as small as 3 to 6 HRB, surface flaws are guaranteed over the entire length, and the manufacturing process is the minimum required. The production cost is low because it has been simplified to a minimum, and by using the wire according to the present invention, it is possible to improve the life of the cold working mold and the dimensional accuracy of the cold worked product, and the like. Further, the present invention has an excellent effect, for example, it can meet the need for quality assurance of surface flaws of molded articles.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a die shape of a drawing die used in the present invention.
[Explanation of symbols]
1 dice 2 bus

Claims (6)

The hot-rolled material of the wire rod is rolled into a bus bar having a dimensional tolerance of ± 0.15 mm or less and an eccentricity difference of 70% or less. As the above processing allowance, the drawing reduction area ratio is set to 5% or less, the die half angle θ of the drawing die shape is set to 5 ° to 35 °, and cold drawing is performed and overcurrent flaw detection is performed. Method for manufacturing inexpensive wires for cold working that guarantees the entire length. The steel for wire rods is, as a steel component, in mass%, C: 0.08 to 1.10%, Si: 1.5% or less, Mn: 1.5% or less, S: 0.100% or less, Ni: The steel according to claim 1, wherein the steel contains 4.0% or less, Cr: 10% or less, Mo: 1.5% or less, Cu: 2.0% or less, and the balance is Fe and unavoidable impurities. A method for manufacturing an inexpensive wire for cold working, which has a low hardness and guarantees surface flaws over the entire length. The steel composition according to claim 2, further comprising at least one of V: 0.40% or less, Nb: 0.40% or less, and Ti: 0.20% or less. 2. The method for producing an inexpensive cold working wire rod having low hardness and guaranteed surface flaws over the entire length according to 2. In addition to the steel components according to claim 2, Pb: 0.30% or less, Bi: 0.20% or less, Se: 0.20% or less, Te: 0.10% or less, and Ca: 200 ppm or less 3. The method for producing an inexpensive cold working wire according to claim 2, wherein the wire contains at least one or more kinds and has low hardness and surface flaws are guaranteed over the entire length. In addition to the steel components according to claim 3, Pb: 0.30% or less, Bi: 0.20% or less, Se: 0.20% or less, Te: 0.10% or less, and Ca: 200 ppm or less The method for producing an inexpensive cold working wire according to claim 3, wherein the wire includes at least one or more kinds and has low hardness and surface flaws are guaranteed over the entire length. Low hardness characterized by being made of carbon steel for machine structure, alloy steel for machine structure or high carbon chromium bearing steel manufactured by the method according to any one of claims 1 to 5, and reducing surface flaws. An inexpensive wire for cold working guaranteed over the entire length.

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