JP2009208112A - Equipment for manufacturing bar steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment for manufacturing bar steel wherein heat treatment which has been conventionally applied in an off-line before cold working is omitted. <P>SOLUTION: The equipment for manufacturing the bar steel includes a roughing mill, an intermediate mill, a finishing mill and a cutting machine, on the poststage of a heating furnace and/or an introduction heating furnace, wherein an induction heating apparatus is provided at one place or two or more places in positions on the inlet sides or the outlet sides of various rolling mills or between the stands inside the roughing mill or the intermediate mill, and water cooling equipment for performing quick cooling of the bar steel after cutting is provided on the outlet side of the cutting machine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a steel bar manufacturing facility, in particular, a rolling material made of austenitic stainless steel is heated in a heating furnace and / or an induction heating furnace, and then rolled in a roughing mill, an intermediate rolling mill and a finishing rolling mill. The present invention relates to a steel bar manufacturing facility for cutting to a predetermined length with a cutting machine.

  In general, for example, a steel bar made of austenitic stainless steel such as SUS303 and SUS304 is hot-worked and then processed into small parts such as bolts, nuts, and screws by cold working such as wire drawing, tension, and cutting. In many cases, prior to these processes, a rolling structure recovery process and a precipitated carbide solution treatment are performed by off-line heat treatment.

The reason for this is that when it is hot-rolled, the hardness is high. If cutting, wire drawing, and cold forging are performed as they are, breakage cracks are likely to occur. This is because a large amount of power is required and wear of expensive processing tools such as a die and a die is increased, which is uneconomical.
Moreover, it is because carbide | carbonized_material precipitates during the cooling after rolling and corrosion resistance has deteriorated greatly.

  Therefore, for example, in Japanese Patent Application Laid-Open No. Sho 62-146221 (Patent Document 1 below), a stage in which the material before finish rolling is reheated to a temperature range of 1100 to 1300 ° C. and a material at a high temperature after finish rolling is 850. The manufacturing method of the austenitic stainless steel wire rod which can abbreviate | omit the solution treatment before cold working by having the step of rapidly cooling about a temperature range of -550 degreeC is described.

However, the method described in Patent Document 1 has not been realized because conditions such as the installation position of the induction heating device and cooling conditions that can eliminate the solution treatment that is an off-line heat treatment have not been sufficiently studied.
JP 62-146221 A

  Accordingly, the present invention solves the problems of the prior art as described above, and heats a rolling material made of austenitic stainless steel in a heating furnace and / or an induction heating furnace, and provides a roughing mill, an intermediate rolling mill, and a finish. It is an object of the present invention to provide a steel bar manufacturing facility that can omit the heat treatment that has been performed offline before cold working in a steel bar manufacturing process such as rolling with a rolling mill.

The gist of the present invention is the following contents as described in the claims.
(1) A steel bar manufacturing facility having a roughing mill, an intermediate rolling mill, a finish rolling mill, and a cutting machine at the latter stage of the heating furnace and / or induction heating furnace,
While having an induction heating device in one place or two or more places in the position between the stands in the entrance side or exit side of the various rolling mills or in the rough rolling mill or the intermediate rolling mill,
A steel bar manufacturing facility comprising a water-cooling system for rapidly cooling the steel bar after cutting on the outlet side of the cutting machine.
(2) The water cooling equipment is a water spout that sprays water spray from above and below the steel bar.

The steel bar manufacturing equipment according to (1), which is a lathe cooling equipment.
(3) The steel bar manufacturing equipment according to (1) or (2), wherein the water spray cooling equipment includes spray nozzles arranged asymmetrically above and below the steel bar.
<Action>
According to the invention of (1), by raising the steel material temperature by an induction heating device installed between the stands of the rough rolling mill and / or between the rough rolling mill and the intermediate rolling mill, The structure that has been hardened by hot rolling is recovered and softened, and the steel material after cutting is rapidly cooled with a water-cooling facility to suppress carbide precipitation and prevent deterioration of corrosion resistance, thereby eliminating the subsequent heat treatment step. can do.
A subsequent heat treatment step can be omitted by rapidly cooling the steel material after rolling with a water-cooling facility to suppress precipitation of carbides and soften the steel material.
According to the invention of (2), since the water cooling equipment is a water spray cooling equipment, and the water spray can be sprayed from the top and bottom of the steel bar, the bending of the steel bar can be reduced to 3 mm / M or less. There is no problem in the operation of the cutting machine (standard saw).
According to the invention of (3), since the water spray cooling equipment has the spray nozzles disposed asymmetrically above and below the steel bar, the water spray can be randomly sprayed on the steel bar, so that the steel material temperature is made more uniform. be able to.

  According to the present invention, it is possible to provide a steel bar manufacturing facility that can omit the heat treatment that has been performed off-line before cold working.

    Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.

    FIG. 1 is a diagram illustrating a conventional steel bar manufacturing facility (a) and a steel bar manufacturing facility (b) of the present invention.

    In FIG. 1, 1 is a rough rolling mill, 2 is an intermediate rolling mill, 3 is a finish rolling mill, 4R / S is a cutting machine, 5 is a cooling bed, WB furnace is a walking beam furnace (heating furnace), and IH is an induction heating device. Indicates.

    In the steel bar manufacturing facility, first, a steel bar rolled material is heated to, for example, 1125 ° C. in a WB furnace, and heated to a required heating temperature, for example, to 1200 ° C. using an induction heating apparatus IH, and then kept in a heat retaining furnace. After that, for example, a total reduction of 88 to 98% is rolled by the rough rolling mill 1, the intermediate rolling mill 2 and the finish rolling mill 3 and cooled in the cooling bed 5 to produce steel bars having various outer diameter sizes. it can.

    The conventional steel bar manufacturing equipment shown in FIG. 1 (a) is a steel bar manufacturing equipment having a roughing mill 1, an intermediate rolling mill 2, and a finishing rolling mill 3 at the rear stage of a heating furnace and / or an induction heating furnace. Since the carbide precipitates in order to air-cool the steel material after rolling in the cooling floor 5 on the exit side of the finish rolling mill 3, as a post-process, it is immersed in a water tank after being subjected to softening treatment and solution treatment in an off-line heat treatment furnace. Therefore, an immersion cooling bath that rapidly cools is necessary.

  The manufacturing equipment for the steel bar of the present invention shown in FIG. 1 (b) is a steel bar having a roughing mill 1, an intermediate rolling mill 2, a finishing rolling mill 3 and a cutting machine 4 at the latter stage of the heating furnace and / or induction heating furnace. It is a production facility, and the position between the stands in the entry side or the exit side of the various rolling mills, the rough rolling mill, or the intermediate rolling mill (the positions indicated by (1) to (6) in FIG. 1B). In addition to having an induction heating device in one place or two places or more, the outlet side of the cutting machine 4 has water cooling equipment for rapidly cooling the steel bar after cutting.

    According to the present invention, for example, a steel bar made of austenitic stainless steel is heated in a heating furnace and / or an induction heating furnace, and is rolled in a roughing mill 1, an intermediate rolling mill 2 and a finishing rolling mill 3. In Fig. 1 (b), the steel material temperature is raised by an induction heating device installed at one or two or more locations shown in (1) to (6), the finishing temperature is raised, and hot rolling is performed. While recovering the hardened structure, the steel material after cutting is rapidly cooled with water-cooling equipment to suppress the precipitation of carbides and prevent deterioration of corrosion resistance, thereby omitting the offline heat treatment step.

  In this invention, since it can heat in the state with the moving speed | rate of steel materials small, so that it installs in the upstream stage of the rolling process which consists of three steps, heating efficiency can be made high. On the other hand, the steel material temperature (hereinafter referred to as the finishing temperature) on the entry side of the cutting machine 4 becomes easier as it is installed at the downstream stage.

    The finish rolling mill 3 used in the present invention includes a precision rolling mill.

  FIG. 2 is a diagram comparing heat treatment patterns in a conventional steel bar manufacturing method (a) and a steel bar manufacturing method (b) of the present invention.

  As shown in FIG. 2 (a), conventionally, C: about 0.07% by mass of austenitic stainless steel, the finishing temperature on the exit side of the finishing mill 3 is set to 910-1020 ° C. By cooling to the air, for example, it was cooled to room temperature with a steel bar of 62 mmΦ at a cooling rate of about 0.4 ° C./sec. Therefore, before performing cold working on bolts, nuts, screws, etc. again, Heating to about 1050 ° C. and performing offline heat treatment, for example, rapid cooling at a cooling rate of about 15 ° C./sec by immersion water cooling required softening of the rolled structure and solution treatment of carbide.

  Therefore, in the present invention, as shown in FIG. 2B, for example, an induction heating device IH is installed between the roughing mill 1 and the intermediate rolling mill 2 (position (3) in FIG. 1B). The steel material being rolled is heated up and cooled rapidly by spraying cooling water from the top and bottom of the steel material at a cooling floor 5 of, for example, less than 1 (up / down) water volume ratio (up / down), for example (in-line). Since the material can be adjusted by heat treatment), the conventional offline heat treatment can be omitted.

  FIG. 3 is a view illustrating a water spray cooling device used in the present invention, where (a) is a side view and (b) is a plan view showing the arrangement of upper spray nozzles or lower spray nozzles.

    By spraying water spray from above and below the steel bar with a spray nozzle as shown in FIG. 3 at a water / water ratio (up / down) of less than 1, the bending of the steel can be reduced to 3 mm / M or less.

  The upper and lower surfaces of the steel can be uniformly cooled by spraying the water spray from the top and bottom of the steel at a water / water ratio of less than 1 (up / down), and the bending per 1M length of the steel bar is 3mm / M or less. be able to. Thereby, it can be in the tolerance | permissible_range of the cutting machine 4 of a steel bar, and does not cause trouble in operation.

The water spray nozzles are arranged in a staggered arrangement in which the relative positional relationship between the upper nozzle group and the lower nozzle group shown in FIG. Since the spray can be sprayed on the steel material at random, the steel material temperature can be made more uniform.
In addition, a pitch means here the space | interval of the steel material longitudinal direction of the nozzle row arrange | positioned on the straight line of the orthogonal | vertical direction with respect to the longitudinal direction of steel materials.

  Ingredients shown in Table 1 and the balance are Fe and unavoidable impurities, and an induction heating device is installed at the position (3) in FIG. Examples are shown in Table 2, NO.1, 5-8.

    Moreover, as a special use example of the equipment according to the present invention, after hot rolling and cooling in the cooling bed 5, the steel material once stored outside the line is used for the roughing mill 1 and the intermediate rolling mill 2 shown in FIG. Examples No. 2 to No. 4 in Table 2 show examples of charging into the line from the space (part A in FIG. 1) and performing cooling in the intermediate rolling, finish rolling, and cooling bed 5.

The finishing temperature in Table 2 indicates the steel material temperature (° C.) on the cutting machine 4 entry side, the rapid cooling start temperature indicates the temperature at which the steel material starts to be cooled in the cooling bed 5, and the bending is per 1M of the steel bar length. Indicates the amount of bending (mm / M).
In addition, the steel material temperature measured the surface of the steel material with the radiation thermometer. Precipitation of carbide was determined by etching with JISG0571 (stainless oxalic acid etching test method).

    Nos. 1 to 3 have a finishing temperature of 1030 ° C. or higher by an induction heating furnace installed between a rough rolling mill and an intermediate rolling mill, so that the structure hardened in the rolling process is recovered, tensile strength, Mechanical properties such as proof stress and hardness are good, the cooling start temperature is 950 ° C or higher, and the cooling rate is 4 ° C / sec or higher, so that solution treatment is sufficient and precipitation of carbide is recognized. I couldn't.

  Among these, No. 3 had an inappropriate water / water ratio and a large bend.

  In No. 4, when the finishing temperature was 1030 ° C. or less, the structure was not recovered in the rolling process, and the structure became fine and hard, and the proof stress was high.

  In No. 5, since the cooling rate in the cooling bed 5 was low, precipitation of carbide was observed.

  Like No. 4, No. 6 had higher yield strength due to insufficient temperature after finish rolling.

  No. 7 is an example carried out in a conventional production facility. Since the cooling rate is low because of cooling in the cooling bed 5, precipitation of carbide is observed, and due to insufficient finishing temperature, tensile strength, proof stress, and hardness are high. became.

  No. 8 is an example in which the steel material heated by conventional manufacturing equipment and off-line heat treatment is immersed in water (deep immersion), but there is a difference in the cooling part of the steel material, and the bending becomes large.

本発明の設備を使用して鋼材に応じた温度条件、冷却条件処理する場合にはオフライン熱処理を施さなくても所定の特性を確保することができることからから本発明の効果が確認された。

The effect of the present invention was confirmed from the fact that when the temperature condition and the cooling condition treatment according to the steel material are performed using the equipment of the present invention, the predetermined characteristics can be secured without performing the offline heat treatment.

It is a figure which illustrates the conventional steel bar manufacturing equipment (a) and the steel bar manufacturing equipment (b) of the present invention. It is the figure which contrasted the heat processing pattern in the manufacturing method (a) of the conventional steel bar, and the manufacturing method (b) of the steel bar of this invention. It is a figure which illustrates the water spray cooling device used for this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rough rolling mill 2 Intermediate rolling mill 3 Finish rolling mill 4 R / S cutting machine 5 Cooling bed WB furnace Walking beam furnace (heating furnace)
IH induction heating device

Claims (3)

A steel bar manufacturing facility having a roughing mill, an intermediate rolling mill, a finish rolling mill and a cutting machine at the latter stage of the heating furnace and / or induction heating furnace,
While having an induction heating device in one place or two or more places in the position between the stands in the entrance side or exit side of the various rolling mills or in the rough rolling mill or the intermediate rolling mill,
A steel bar manufacturing facility comprising a water-cooling system for rapidly cooling the steel bar after cutting on the outlet side of the cutting machine.     The said water-cooling equipment is a water spray cooling equipment which sprays a water spray from the upper and lower sides of the said steel bar, The manufacturing equipment of the steel bar of Claim 1 characterized by the above-mentioned.   The said water spray cooling equipment has the spray nozzle arrange | positioned asymmetrically up and down of the said steel bar, The manufacturing apparatus of the steel bar of Claim 1 or Claim 2 characterized by the above-mentioned.

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