JP2019214070A - Strip steel wire coil manufacturing method - Google Patents

Abstract

To manufacture a closely wound strip steel wire coil which can suppress cross-sectional deformation of a strip steel wire after winding.SOLUTION: A strip steel wire coil 2 is manufactured in such a manner that a strip steel wire 1, which is obtained by continuous rolling on a rolling line 10, is cooled by a cooling line 20, and thereafter, is wound by a winder 30. The cooling line 20 comprises plural water-cooled parts which are located at intervals, intervals between respective water-cooled parts are provided as plural inter-water-cooled part recuperation sections, and the interval between the water-cooled part, which is positioned on the most downstream side, and the winder 30 is provided as a final stage recuperation section. At the first water-cooled part from an upstream side, a surface temperature of the strip steel wire 1 is so made as to be lower than A1 transformation point by 100°C or more, and at the first inter-water-cooled recuperation section from the upstream side, the surface temperature of the strip steel wire 1 is so made as to be A1 transformation point or more. The surface temperature of the strip steel wire 1 during winding is so made as to be A1 transformation point or less. The winder 30 has a spool 31 and an alignment mechanism 32 in front of the spool 31, and closely winding the strip steel wire 1, which is aligned by the alignment mechanism 32, on the spool 31, thereby obtaining the strip steel wire coil 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for cooling a strip steel wire obtained by rolling and then winding it into a coil.

  It is well known that a steel material such as a heated billet or bloom is continuously rolled to obtain a strip steel wire, and after cooling the strip steel wire, it is wound into a coil. In a system provided for manufacturing such a strip steel wire coil, a rolling line, a cooling line, and a winding machine are sequentially arranged along a rolling direction. The cooling line is composed of a plurality of cooling devices spaced from each other.

  In the rolling method disclosed in Patent Literature 1, a steel bar at about 1000 ° C. sent from a final finishing rolling mill of a rolling line is cooled stepwise by applying water with a four-stage cooling device. Typically, the film is wound by a winder at a temperature exceeding 800 ° C.

  Patent Document 1 does not disclose a specific configuration of a winding device and a method of winding a strip steel wire. Generally, the rolled strip steel wire is wound loosely. For example, as shown in Patent Literature 2 or the like, a rolled strip steel wire is spirally dropped on a support base.

JP 2009-241133 A JP 2005-246401 A

The loosely wound strip steel wire coil as described above was bulky and could not be stably stored, resulting in poor storage and transportation efficiency.
The present inventors are studying winding a rolled strip steel wire into a close-wound coil in order to increase the efficiency of storage and transportation. In other words, the winding machine has a spool and an alignment mechanism in front of the spool.By rotating the spool while aligning the strip steel wire by the alignment mechanism, tension is applied to the strip steel wire, and the strip steel wire is tightly packed on the spool. To take up.

  However, when the strip steel wire is tightly wound by applying tension to the strip steel wire in a high-temperature region where the hot deformation resistance exceeding 800 ° C. is small as in Patent Literature 1, the cross-sectional deformation is caused by the tightening force of the strip steel wire itself during winding. Occurs. In addition, since a transformation accompanied by a volume expansion from [austenite] to [ferrite + pearlite] occurs as the temperature decreases after winding, the cross-sectional deformation of the tightly wound strip steel wire is promoted. Further, if the cooling line is cooled down to a temperature that does not cause cross-sectional deformation at the time of winding while suppressing the equipment length of the cooling line, the structure of the strip steel wire is transformed into bainite or martensite.

The present invention has been made in order to solve the above-described problems, and a strip steel wire obtained by continuous rolling in a rolling line was cooled by a cooling line arranged downstream of a final finishing rolling mill in the rolling line. Thereafter, by winding with a winding machine arranged downstream of the cooling line, to produce a strip steel wire coil, the cooling line comprises a plurality of water cooling units arranged at intervals, the plurality of The section between the water cooling sections is provided as a plurality of water cooling section recuperation sections, and the section between the water cooling section and the winder located at the most downstream side of the plurality of water cooling sections is a final stage recuperation section. Provided, in the method of manufacturing a coil of a bar steel wire, the surface temperature of the bar steel wire is reduced every time the steel sheet passes through the cooling section, and is increased by the internal heat of the steel bar wire each time the steel sheet passes through the recuperator.
In the first water cooling section from the upstream in the plurality of water cooling sections, the surface temperature of the strip steel wire is lowered by 100 ° C. or more from the A1 transformation point, and between the first water cooling sections in the plurality of water cooling sections from the upstream in the recuperation section. In the recuperation section, the surface temperature of the strip steel wire is raised to the A1 transformation point or higher, and the surface temperature of the strip steel wire at the time of winding is reduced to the A1 transformation point or lower. Wherein the strip steel wires aligned by the alignment mechanism are closely wound around the spool to obtain the strip steel wire coil.

According to the above method, since the surface temperature of the strip steel wire at the time of winding is equal to or lower than the A1 transformation point, the cross-sectional deformation of the strip steel wire can be suppressed even if the strip steel wire is densely wound.
In the first water-cooled part, the surface temperature of the bar steel wire is strongly cooled so as to be lower than the A1 transformation point by 100 ° C. or more, and then, in the first recuperator, the surface temperature of the bar steel wire is re-heated to the A1 transformation point or higher. Therefore, transformation to bainite or martensite due to rapid cooling can be avoided.

Preferably, the surface temperature of the strip steel wire at the time of the winding is set to 700 ° C. or less.
According to the above method, it is possible to more reliably suppress the cross-sectional deformation of the strip steel wire after winding.

Preferably, the surface temperature of the strip steel wire at the time of the winding is 620 ° C or higher.
According to the above method, it is possible to avoid an increase in the length of the cooling line due to excessive cooling of the strip steel wire.

Preferably, in a second water cooling section of the plurality of water cooling sections, the surface temperature of the strip steel wire is lowered by 150 ° C. or more from the A1 transformation point, and a second water cooling section of the plurality of water cooling section recuperation sections is provided. In the hot part, the surface temperature of the strip steel wire is raised to the A1 transformation point or higher.
According to the above method, it is possible to contribute to shortening of the cooling line while avoiding transformation to bainite or martensite.

Preferably, in a third water cooling part of the plurality of water cooling parts, the surface temperature of the strip steel wire is lowered by 200 ° C. or more from the A1 transformation point.
According to the above method, the cooling line can be further shortened.

Preferably, the surface temperature of the strip steel wire is set to the lowest temperature in the cooling line in the upstream water cooling section of the plurality of water cooling sections.
According to the above method, the cooling line can be further shortened.

Preferably, in each of the plurality of water cooling sections, the surface temperature of the strip steel wire is set to be lower than the A1 transformation point by 100 ° C. or more.
According to the above method, it is possible to more reliably suppress the cross-sectional deformation of the strip steel wire after winding, and to shorten the cooling line.

Compared with the passage time of each bar steel wire of the plurality of water cooling sections, the passage time of the bar steel wire in the water-cooling section recuperation section following each water cooling section is long, and the bar steel wire in the final stage recuperation section The passage time of the wire is longer than the passage time of the bar steel wire in the water-cooled recuperator.
According to the above method, reheating of the surface of the strip steel wire can be reliably performed, and transformation to bainite or martensite can be reliably prevented.

Preferably, in the plurality of water cooling sections, the passage time of the strip steel wire in the upstream water cooling section is longer than the passage time of the strip steel wire in the downstream water cooling section, and in the plurality of water cooling section recuperation sections, The passage time of the above-mentioned bar steel wire in the water-cooling part recuperation part on the side is shorter than the passage time of the strip steel wire in the water-cooling part recuperation part on the downstream side.
According to the above method, since the internal temperature of the strip steel wire is high on the upstream side and the recuperation of the surface temperature is fast and the recuperation section between the water cooling sections is shortened, it is possible to contribute to shortening of the cooling line. .

  The diameter of the strip steel wire is 9.53 to 15.9 mm, and the speed of the strip steel wire in the cooling line is 11 to 35 m / sec.

  ADVANTAGE OF THE INVENTION According to this invention, the tightly wound strip steel wire coil which can suppress the cross-sectional deformation of a strip steel wire after winding can be manufactured, moreover, transformation to bainite or martensite is avoided, and the length of the cooling line can be increased. Can be avoided.

It is a schematic diagram showing the manufacturing system of the bar steel wire coil concerning one embodiment of the present invention. It is the schematic which shows the winding machine of the said manufacturing system. It is sectional drawing which shows typically the bar steel wire rod coil closely wound on the spool of the said winding machine. In the cooling line of the manufacturing system, it is a graph showing a stepwise cooling process of a rolled bar steel wire having a name of D10 (nominal diameter of 9.53 mm), where the surface temperature of the bar is denoted by A, the center temperature is denoted by B, The average temperature is indicated by symbol C. In the cooling line of the above-mentioned manufacturing system, it is a graph which shows the process of the gradual cooling of the rolled strip steel wire of nominal name D13 (nominal diameter 12.7mm). The average temperature is indicated by symbol C. In the cooling line of the above-mentioned manufacturing system, it is a graph which shows the process of stepwise cooling of the rolled strip steel wire of nominal name D16 (nominal diameter 15.9 mm), the surface temperature of the strip steel wire is code A, the center temperature is code B, The average temperature is indicated by symbol C.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a manufacturing system for manufacturing a strip steel wire coil includes a rolling line 10, a cooling line 20, and a winder 30 that are linearly arranged along a rolling direction.

  The rolling line 10 includes a heating furnace 11, a rough rolling mill 12, an intermediate rolling mill 13, a finishing rolling mill 14, and a final finishing rolling mill 15 arranged in order from the upstream side to the downstream side. The billet or bloom heated in the heating furnace 11 is continuously rolled in a rough rolling mill 12, an intermediate rolling mill 13, a finishing rolling mill 14, and a final finishing rolling mill 15, and its cross section is reduced step by step. From the final finish rolling mill 15, it comes out as a strip steel wire 1 having a desired size.

  On the rolling line 10, an inlet cooling device 16 is arranged on the inlet side (upstream side) of the final finishing mill 15. The inlet-side cooling device 16 is based on a transition of a measurement value of a thermometer disposed between the finishing mill 14 and the inlet-side cooling device 16 or between the inlet-side cooling device 16 and the final finishing mill 15. By controlling the amount of water supplied to the inlet-side cooling device 16, the temperature of the strip steel wire 1 at the exit of the final finishing mill 15 is adjusted to fall within a set temperature range, and the temperature variation of each strip steel wire 1 is reduced. Suppress.

  The cooling line 20 is configured by a group of cooling devices arranged on the exit side (downstream side) of the final finishing mill 15. The cooling device group has seven (plural) cooling devices 21 to 27 arranged at intervals along the cooling line 20. Hereinafter, these cooling devices 21 to 27 will be referred to as first to seventh cooling devices in order from the upstream side to the downstream side. The strip steel wire 1 coming out of the final finishing mill 15 is cooled stepwise by these cooling devices 21 to 27 and sent to the winding machine 30.

  As shown in FIG. 2, the winding machine 30 includes a spool 31 and an alignment mechanism 32 disposed immediately before the spool 31. A pinch roller 35 is arranged in front of the alignment mechanism 32. The spool 31 is rotated by a drive motor (not shown) in a state where the strip steel wire 1 is sandwiched between the pinch rollers 35, and the rotation of the spool 31 is applied to the strip steel wire 1 so that tension acts between the pinch roller 35 and the spool 31. Controlled. The alignment mechanism 32 reciprocates in the axial direction of the spool 31 with the rotation of the spool 31, and aligns the strip steel wire 1. As a result, the strip steel wire 1 is wound tightly in layers as shown in FIG. 3, and the strip steel wire coil 2 is obtained.

  The strip steel wire coil 2 wound on the spool 31 is removed from the production line.

  Next, the cooling line 20 will be described in detail. Although the arrangement of the cooling devices 21 to 27 is schematically shown in FIG. 1, actually, the arrangement is as follows. Regarding the intervals between the adjacent cooling devices 21 to 27, the interval D1 between the first cooling device 21 and the second cooling device 22 on the most upstream side is the smallest. An interval D2 between the second cooling device 22 and the third cooling device 23 is about twice as large as the interval D1. The interval between adjacent cooling devices from the third cooling device 23 to the seventh cooling device 27 is about twice as large as the interval D2. The distance between the seventh most downstream cooling device 27 and the spool 31 of the winder 30 is more than twice as long.

The cooling devices 21 to 27 of the present embodiment can adjust the length at which water is injected.
In the following description, the portions where water is actually injected in the cooling devices 21 to 27 to cool the strip steel wire 1 are sequentially arranged from the upstream to the first to seventh water cooling portions (No. 1 water cooling to No. 7 water cooling). That.
In the interval between the adjacent water cooling units, the distance d1 between the first upstream water cooling unit (No. 1 water cooling) and the second upstream water cooling unit (No. 2 water cooling) is the narrowest. The distance d2 between the second water cooling section (No. 2 water cooling) and the third water cooling section (No. 3 water cooling) is about twice as large as d1. The distance between adjacent water cooling sections from the third water cooling section (No. 3 water cooling) to the seventh water cooling section (No. 7 water cooling) is about twice as large as d2. The distance between the seventh downstream water-cooling section (No. 7 water-cooling) and the spool 31 of the winder 30 is more than twice as long.
In a section between the water cooling sections of the cooling devices 21 to 27, as described later, the surface temperature of the strip steel wire 1 increases due to internal heat, but this section is first to sixth recuperation sections in order from the upstream side. (Reheat section between water cooling sections, No. 1 reheat to No. 6 reheat).
A section from the water-cooling section (seventh water-cooling section, No. 7 water-cooling section) of the cooling device 27 on the most downstream side to the spool 31 (winding section) of the winding machine 30 is a seventh recuperation section (final-stage recuperation). Part, No. 7 reheating).

The cooling process of the strip steel wire 1 in the cooling line 20 will be schematically described. As shown in FIGS. 4 to 6, each time the strip steel wire 1 passes through each of the water cooling sections of the cooling devices 21 to 27, it is bathed in water and cooled stepwise. The surface temperature (indicated by the symbol A in the figure) of the strip steel wire 1 drops sharply because it is in direct contact with water. In the process of passing through the heat recovery section, the surface temperature of the strip steel wire 1 rapidly rises (recovers) due to heat transfer from the center. As described above, the surface temperature of the strip steel wire 1 decreases while fluctuating sharply in the cooling line 20.
The temperature of the central portion of the strip steel wire 1 (indicated by the symbol B in the drawing) gradually decreases. The average temperature of the strip steel wire 1 (the average temperature in the cross section indicated by the symbol C in the figure) gradually decreases under the influence of the surface temperature.

  In the seventh recuperation section on the most downstream side, after the surface temperature of the strip steel wire 1 rises sharply near the outlet of the seventh water cooling part, it continues to rise gradually, and the center temperature and the average temperature decrease gradually. . As a result, when the strip steel wire 1 is wound by the spool 31, the center temperature and the surface temperature are substantially equal or the difference is about 10 ° C. or less.

In the present invention, the surface temperature of the strip steel wire 1 when it is wound up by the spool 31 of the winding machine 30 is set to the A1 transformation point (727 ° C.) or lower. As a result, at the time of winding, at least on the surface, the transformation of the structure from [austenite] to [ferrite + pearlite] has been completed,
Even if tight tension is applied to the spool 31 by applying tension to the strip steel wire 1, cross-sectional deformation of the strip steel wire 1 can be suppressed.

Preferably, the surface temperature of the strip steel wire 1 when wound by the spool 31 is set to 700 ° C. or less. By thus sufficiently lowering the surface temperature from the A1 transformation point, the transformation of the structure into [ferrite + pearlite] is completed in almost all regions at the time of winding, and the deformation of the strip steel wire 1 The resistance is also large, and even if the tension is applied to the strip steel wire 1 and the spool 31 is tightly wound around the spool 31, the cross-sectional deformation of the strip steel wire 1 can be reliably prevented.

Preferably, the surface temperature of the strip steel wire 1 when wound by the spool 31 is set to 620 ° C. or higher. At 620 ° C., the transformation of the structure has already been completely completed, and excessive cooling causes the cooling line 20 to become longer.
More preferably, the surface temperature of the strip steel wire 1 during winding is 640 to 680 ° C.

  As described above, since the surface temperature of the strip steel wire 1 at the time of winding is significantly lower than the conventional one (800 ° C. or higher), slow cooling of the rolled strip steel wire 1 causes a significant increase in the length of the cooling line 20. In order to avoid the lengthening of the cooling line, it is required to strongly cool the strip steel wire 1. However, if the cooling is performed excessively, the structure of martensite or bainite appears in the strip steel wire 1 and is not JIS standard. Become.

  In the present invention, the cooling line 20 is strongly cooled in the upstream water cooling section and sufficiently recuperated in the cooling line 20 and is slowly cooled in the downstream water cooling section, without being transformed into bainite or martensite. Avoids the lengthening of.

  Specifically, in the first water-cooled portion, the surface temperature of the bar steel wire 1 is lowered by 100 ° C. or more from the A1 transformation point, and in the first recuperation portion, the surface temperature of the bar steel wire 1 is raised to the A1 transformation point or more. Let me. Since the surface temperature of the strip steel wire 1 is the highest at the first water cooling section entrance, the highest cooling effect can be obtained by performing strong cooling in the first water cooling section. In the first recuperator, the surface temperature of the strip steel wire 1 is immediately increased to the A1 transformation point or higher, so that transformation to bainite or martensite does not occur.

  Preferably, the surface temperature of the strip steel wire 1 is lowered by 100 ° C. or more, more preferably by 150 ° C. or more from the A1 transformation point in the second water-cooled section, and is raised again to the A1 transformation point or more in the second recuperation section. This can contribute to shortening of the cooling line while avoiding transformation to bainite or martensite.

  More preferably, even in the third water-cooled portion, the surface temperature of the strip steel wire 1 is made lower than the A1 transformation point by 100 ° C. or more, more preferably 200 ° C. or more. Thereby, the cooling line can be further shortened.

  Due to the strong cooling on the upstream side as described above, the surface temperature of the strip steel wire 1 becomes the lowest temperature in the cooling line 20 in the upstream water cooling unit in the plurality of cooling units of the cooling devices 21 to 27. Specifically, the temperature becomes the lowest at the outlet of the third water cooling unit. Thereby, the cooling line can be further shortened. The minimum temperature is preferably from 450C to 540C. Note that the lowest temperature may be realized by the first or second water cooling unit.

  Preferably, in all the water-cooled parts, the surface temperature of the strip steel wire 1 is set to be lower than the A1 transformation point by 100 ° C. or more. Thereby, it is possible to more reliably suppress the cross-sectional deformation of the strip steel wire 1 after winding and to shorten the cooling line.

  In the present embodiment, the length of the water-cooled portion is adjusted for strong cooling on the upstream side. The longer the water-cooled portion, the longer the passage time of the water-cooled portion and the greater the cooling capacity. Specifically, the upstream water cooling section (specifically, the first to second water cooling section or the first to third water cooling section) of the cooling line 20 is replaced with the downstream water cooling section (third to seventh water cooling section). Water cooling section or the fourth to seventh water cooling sections).

  The longer the recuperator, the longer the passage time of the recuperator and the greater the recuperative capacity. The recuperation section is longer than the immediately preceding water cooling section so that a sufficient recuperation effect can be obtained. The first recuperation section is the shortest, the second recuperation section is about twice as large as the first recuperation section, and the third to sixth recuperation sections are about twice as large as the second recuperation section. It is twice. Because the internal temperature of the strip steel wire 1 is higher on the upstream side, a sufficient recuperation effect can be obtained even if the recuperator is short.

  The seventh recuperation section is the longest and is at least twice as long as the third to sixth recuperation sections. Since the heat is recovered for a long time in the seventh heat recovery section, the surface temperature and the center temperature become substantially equal.

[Example]
As a material of the strip steel wire 1, for example, JIS standard SD295 or SD345 is used. Incidentally, the following components are contained as examples of the components of SD295.
C: 0.18 to 0.27%
Si: 0.10 to 0.55%
Mn: 0.45 to 1.50%
The following components are included as examples of the components of SD345.
C: 0.20 to 0.27%
Si: 0.10 to 0.55%
Mn: 0.65 to 1.50%

The diameter (nominal diameter) of the strip steel wire 1 is not particularly limited, but is applied to 10 to 16 mm (JIS G3112: 2010, designation D10 to D16, nominal diameter 9.53 to 15.9 mm).
The speed of the strip steel wire 1 at the exit of the final finish rolling mill 15 is 11 to 35 m / sec.
A billet or bloom heated to about 1000 ° C. (for example, 1030 ° C.) in a heating furnace is continuously rolled in the rolling line 10, and the surface temperature of the strip steel wire 1 at the exit of the final finishing mill 15 becomes 950 to 1000 ° C. . As described above, the surface temperature can be controlled by the inlet-side cooling device 16.

Hereinafter, the cooling process of the bar steel wire 1 of each size of the nominal name D10 (nominal diameter of 9.53 mm), the nominal name D13 (nominal diameter of 12.7 mm), and the nominal name D16 (nominal diameter of 15.9 mm) will be described.
Table 1 shows the length of the water-cooled portion (No. 1 water-cooled to No. 7 water-cooled) and the recuperator (No. 1 re-heated to No. 7 re-heated) in each size.

Example 1 (D10 nominal diameter 9.53 mm)
As shown in Table 1, the length of the first water-cooled portion (No. 1 water-cooled) 5.0 m away from the outlet of the final finishing mill 15 is 2.6 m, when cooling the D10 strip steel wire 1. The third water cooling section (No. 3 water cooling) is 3.3 m, and the fourth to seventh water cooling sections (No. 4 water cooling to No. 7). (Water cooling) is 0.6 m. The first recuperation section (No. 1 recuperation) is the shortest at 4.6 m, the second recuperation section (No. 2 recuperation) is 10.0 m, and the third to sixth recuperation sections. (No. 3 recuperation to No. 6 recuperation) is 19.4 to 22.2 m, and the seventh recuperation section (No. 7 recuperation) is 50.0 m.

  When the speed of the strip steel wire 1 at the exit of the final finishing rolling mill 15 is 30.0 m / sec and the surface temperature immediately before entering the first water cooling section (No. 1 water cooling) is 944 ° C., the D10 strip steel wire is used. When the temperature change of No. 1 was simulated, the result shown in FIG. 4 was obtained.

The surface temperature of the strip steel wire 1 sharply drops in the first water-cooled portion (No. 1 water-cooled), and reaches about 600 ° C. at the outlet thereof, which is 120 ° C. or more (100 ° C. or more) lower than the A1 transformation point. Since the surface temperature is high and the first water-cooled part (No. 1 water-cooled) is long, the temperature drop in the first water-cooled part (No. 1 water-cooled) is maximum. The first recuperator (No. 1 recuperator) is short but has a high center temperature and high average temperature, so the surface temperature rises rapidly due to internal heat and returns to about 780 ° C., which exceeds the A1 transformation point.
The surface temperature drops rapidly even in the second water-cooled part (No. 2 water-cooled), drops to about 570 ° C. which is 150 ° C. or more (100 ° C. or more) lower than the A1 transformation point, and the second recuperated part (No. 2). The temperature rises to about 750 ° C., which exceeds the A1 transformation point.
In the third water-cooled portion (No. 3 water-cooled), the surface temperature rapidly drops again, and reaches 489 ° C., which is 230 ° C. or more (200 ° C. or more) lower than the A1 transformation point. This temperature is the lowest value of the surface temperature of the strip steel wire 1 in the cooling step. At the third long recuperation section (No. 3 recuperation), the surface temperature of the strip steel wire 1 returns from the minimum temperature to about 700 ° C.

  The surface temperature of the strip steel wire 1 is lowered to a temperature lower than the A1 transformation point by 100 ° C. or more even in the fourth to seventh cooling parts (No. 4 water cooling to No. 7 water cooling), and the fourth to seventh recuperation parts are formed. In (No. 4 recuperation to No. 7 recuperation), the temperature rises but the return temperature gradually decreases. Finally, the surface temperature during winding is 649 ° C., and the surface temperature and the center temperature are substantially equal.

Example 2 (D13 nominal diameter 12.7 mm)
As shown in Table 1, the length of the first water-cooled section (No. 1 water-cooled) 3.8 m away from the exit of the final finishing rolling mill 15 is 3.9 m, as shown in Table 1, when cooling the strip steel wire 1 of D13. The third water cooling section (No. 2 water cooling) is 2.1 m, the third water cooling section (No. 3 water cooling) is 1.9 m, and the fourth water cooling section (No. 4 water cooling) is 1.2 m. The seventh to seventh water cooling parts (No. 5 water cooling to No. 7 water cooling) are 0.5 to 0.7 m. The first recuperator (No. 1 recuperator) is the shortest at 4.5 m, the second recuperator (No. 2 recuperator) is 11.2 m, and the third to sixth recuperators. (No. 3 recuperation to No. 6 recuperation) is 19.6 to 21.7 m, and the seventh recuperation section (No. 7 recuperation) is 50.0 m.

  When the speed of the strip steel wire 1 at the exit of the final finishing mill 15 is 23.2 m / sec, and the surface temperature immediately before entering the first water cooling section (No. 1 water cooling) is 944 ° C., the D13 strip steel wire is used. When the temperature change of No. 1 was simulated, the result shown in FIG. 5 was obtained.

The surface temperature of the strip steel wire 1 rapidly decreases in the first water-cooled portion (No. 1 water-cooled), and reaches about 530 ° C., which is 190 ° C. or more (100 ° C. or more) lower than the A1 transformation point at the outlet. Since the surface temperature is high and the first water-cooled part (No. 1 water-cooled) is long, the temperature drop in the first water-cooled part (No. 1 water-cooled) is maximum. The first recuperator (No. 1 recuperator) is short but has a high center temperature and high average temperature. Therefore, the surface temperature rises rapidly due to internal heat and returns to about 740 ° C. which exceeds the A1 transformation point.
The surface temperature also drops sharply in the second water-cooled part (No. 2 water-cooled), drops to about 520 ° C., which is 200 ° C. or more (150 ° C. or more) lower than the A1 transformation point, and the second recuperated part (No. 2). The temperature rises to about 740 ° C., which exceeds the A1 transformation point.
Since the third water-cooled portion (No. 3 water-cooled) is the longest, the surface temperature drops sharply again here to 497 ° C., which is 220 ° C. (200 ° C.) or more lower than the A1 transformation point. This temperature is the lowest value of the surface temperature of the strip steel wire 1 in the cooling step. Since the third recuperator (No. 3 recuperator) is long, it returns from the above minimum temperature to about 720 ° C.

  The surface temperature of the strip steel wire 1 is lowered to a temperature lower than the A1 transformation point by 100 ° C. or more even in the fourth to seventh cooling parts (No. 4 water cooling to No. 7 water cooling), and the fourth to seventh recuperation parts are formed. In (No. 4 recuperation to No. 7 recuperation), the temperature rises but the return temperature gradually decreases. Finally, the surface temperature during winding is 657 ° C., and the difference between the surface temperature and the center temperature is about 3 ° C.

Example 3 (D16 nominal diameter 15.9 mm)
As shown in Table 1, the length of the first water-cooled portion (No. 1 water-cooled) 5.1 m away from the outlet of the final finishing mill 15 is 2.7 m, when the strip steel wire 1 of D16 is cooled, as shown in Table 1. The third water cooling section (No. 2 water cooling) is 1.4 m, the third water cooling section (No. 3 water cooling) is 1.2 m, and the fourth water cooling section (No. 4 water cooling) is 1.2 m. The seventh water-cooled part (No. 5 water-cooled) is 0.7 m, the sixth water-cooled part (No. 6 water-cooled) is 1.3 m, and the seventh water-cooled part (No. 7 water-cooled) is 0.7 m. The first recuperator (No. 1 recuperator) is the shortest at 5.2 m, the second recuperator (No. 2 recuperator) is 11.8 m, and the third to sixth recuperators. (No. 3 recuperation to No. 6 recuperation) is 19.5 to 21.6 m, and the seventh recuperation section (No. 7 recuperation) is 50.2 m.

  When the speed of the strip steel wire 1 at the exit of the final finishing rolling mill 15 is 14.8 m / sec, and the surface temperature immediately before entering the first water cooling section is 935 ° C., the temperature change of the D16 strip steel wire 1 is simulated. Then, the result shown in FIG. 6 was obtained.

The surface temperature of the strip steel wire 1 rapidly decreases in the first water-cooled portion (No. 1 water-cooled), and reaches about 530 ° C., which is 190 ° C. or more (100 ° C. or more) lower than the A1 transformation point at the outlet. Since the surface temperature is high and the first water-cooled part (No. 1 water-cooled) is long, the temperature drop in the first water-cooled part (No. 1 water-cooled) is maximum. The first recuperator (No. 1 recuperator) is short but has a high center temperature and high average temperature. Therefore, the surface temperature rises rapidly due to internal heat and returns to about 760 ° C., which exceeds the A1 transformation point.
The surface temperature also drops sharply in the second water-cooled part (No. 2 water-cooled), drops to about 525 ° C., which is 200 ° C. or more (150 ° C. or more) lower than the A1 transformation point, and the second recuperated part (No. 2). The temperature rises to about 750 ° C., which exceeds the A1 transformation point.
Since the third water-cooled portion (No. 3 water-cooled) is the longest, the surface temperature drops sharply again here to 508 ° C., which is 200 ° C. or more lower than the A1 transformation point. This temperature is the lowest value of the surface temperature of the strip steel wire 1 in the cooling step. Since the third recuperator (No. 3 recuperator) is long, it returns from the above minimum temperature to about 740 ° C.

  The surface temperature of the strip steel wire 1 is lowered to a temperature lower than the A1 transformation point by 100 ° C. or more even in the fourth to seventh cooling parts (No. 4 water cooling to No. 7 water cooling), and the fourth to seventh recuperation parts are formed. In (No. 4 recuperation to No. 7 recuperation), the temperature rises but the return temperature gradually decreases. Finally, the surface temperature during winding is 669 ° C., and the difference between the surface temperature and the center temperature is about 10 ° C.

  As is clear from Table 1, the length of the cooling line 20 from the outlet of the final finishing mill 15 to the spool 31 of the winding device 30 could be suppressed to about 165 m.

  The present invention is not limited to the above embodiment, and various modes can be adopted.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a method of densely winding a hot-rolled strip steel wire.

1 strip steel wire 2 strip steel coil 10 Rolling line 15 Final finishing mill 16 Inlet cooling device 20 Cooling line 21-27 Cooling device 30 Winding machine 31 Spool 32 Alignment mechanism

Claims (10)

After the strip steel wire obtained by continuous rolling in the rolling line is cooled by a cooling line arranged downstream of the final finishing rolling mill of the rolling line, a winding machine arranged downstream of the cooling line By winding in, to produce a strip steel wire coil,
The cooling line includes a plurality of water cooling units disposed at intervals, a section between the plurality of water cooling units is provided as a plurality of water cooling unit recuperators, the most downstream of the plurality of water cooling units The section between the water-cooling section and the winder located in the section is provided as a final-stage recuperator, reduces the surface temperature of the strip steel wire each time it passes through the cooling section, and passes through the recuperator. In the method of manufacturing a coil of a bar steel wire which is raised by the internal heat of the bar steel wire each time,
In the first water cooling section from the upstream in the plurality of water cooling sections, the surface temperature of the strip steel wire is lowered by 100 ° C. or more from the A1 transformation point. In the recuperation section, raise the surface temperature of the above-mentioned bar steel wire above the A1 transformation point,
The surface temperature of the strip steel wire at the time of the winding is set to the A1 transformation point or lower,
The winding machine has a spool and an alignment mechanism in front of the spool, and tightly winds the strip steel wires aligned by the alignment mechanism around the spool to obtain the strip steel wire coil. Method.   The method according to claim 1, wherein a surface temperature of the strip steel wire during the winding is set to 700 ° C. or less.   The method according to claim 2, wherein a surface temperature of the strip steel wire at the time of the winding is set to 620 ° C or higher.   In the second water-cooling section of the plurality of water-cooling sections, the surface temperature of the strip steel wire is lowered by 150 ° C. or more from the A1 transformation point, and in the second water-cooling section of the plurality of water-cooling section recuperation sections. The method for producing a coil of a bar-shaped wire according to any one of claims 1 to 3, wherein the surface temperature of the bar-shaped wire is raised to the A1 transformation point or higher.   The method according to claim 4, wherein a surface temperature of the strip steel wire is lowered by 200 ° C. or more from an A1 transformation point in a third water cooling section of the plurality of water cooling sections.   The method according to claim 1, wherein a surface temperature of the strip steel wire is set to a minimum temperature in the cooling line in an upstream water cooling section of the plurality of water cooling sections. .   The method according to any one of claims 1 to 6, wherein, in each of the plurality of water-cooled portions, the surface temperature of the strip steel wire is lower than the A1 transformation point by 100 ° C or more.   Compared with the passage time of each bar steel wire of the plurality of water cooling sections, the passage time of the bar steel wire in the water-cooling section recuperation section following each water cooling section is long, and the bar steel wire in the final stage recuperation section The method for producing a coil of a bar steel wire according to any one of claims 1 to 7, wherein a customs clearance time of the wire is longer than a passage time of the bar steel wire in the recuperator between the water cooling sections. In the plurality of water cooling sections, the passage time of the strip steel wire in the upstream water cooling section is longer than the passage time of the strip steel wire in the downstream water cooling section,
In the plurality of water-cooling section recuperators, the passage time of the strip steel wire in the upstream water-cooling section recuperator is shorter than the passage time of the strip steel wire in the downstream water-cooling section recuperator. The method for producing a strip steel wire coil according to claim 8, characterized in that:   The steel bar according to any one of claims 1 to 9, wherein a diameter of the steel bar is 9.53 to 15.9 mm, and a speed of the steel bar in the cooling line is 11 to 35 m / sec. Manufacturing method of wire coil.

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