JP2000051934A - Method for cooling hot rolled wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize difference in the cooling rate generated in the longitudinal direction of a layer thickness coil and to control the cut-down amount of a wire by overlapping the bottom of the layer thickness coil to be a preceding lot and top of the layer thickness coil to be the succeeding lot when the hot- rolled wire is placed on a conveyer as the layer thickness coil and conveyed to a cooling zone. SOLUTION: After water-cooling the wire which is hot-rolled with a rolling mill, the wire is placed in a laid state, that is, as the layer thickness coil while winding/forming the wire on the conveyer 5 with a wire winding machine and, after conveying them to a cooling zone with the conveyer 5, wound into a coil shape with a cumulating machine. The top 11 (one turn at the forefront end) of the layer thickness coil 6B to be the succeeding lot is overlapping placed on the bottom 10 (one turn at the end) of the layer thickness coil 6A to be the preceding lot on the conveyer 5 and an overlapped part 12 (superimposed layers) is formed between these layer thickness coils 6A, 6B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling a hot-rolled wire.

[0002]

2. Description of the Related Art In many cases, a method of manufacturing a wire rod by hot rolling involves, as shown in FIG.
0 is placed on the conveyor 51 as a non-concentric offset center in the transport direction, in a winding state that is superimposed on each other, and gradually cooled or air-cooled while being transported by the conveyor 51 as it is. Cooling process.

[0003] A state in which the wire 50 is placed on the conveyor 51 is hereinafter referred to as a "layer thickness coil 52", but is generally treated as a "layer thickness coil" in this specification. Numerical range: ring pitch P, wire diameter d
In this case, the range of (3/4) d ≦ P ≦ (5/4) d is not particularly limited. In the cooling step described above, in the layer thickness coil 52, the number of superposed layers is small at the center in the width direction with respect to the transport direction, that is, the “sparse portion”
On the other hand, on both sides in the width direction, the number of superposed layers is large, that is, due to the “dense portion”, a difference in cooling rate occurs between the sparse portion and the dense portion in the width direction. Failure could occur.

That is, since the sparse portion cools faster than the dense portion, the wire 50 corresponding to the sparse portion has insufficient softening and insufficient adjustment of mechanical properties. So conventionally,
For the purpose of equalizing the cooling rate in the width direction of the layer-thickness coil 52, various techniques for solving the problem have been proposed. JP-B-59-28973, and Japanese Patent Publication No. Sho 59-59, which mainly uses convection of the heat possessed by a wire.
See, for example, the technique described in JP-A-52214).

[0005]

SUMMARY OF THE INVENTION Hot rolled wire 5
0 is placed on the conveyor 51 as the layer thickness coil 52, between the lots of the layer thickness coil 52, the bottom 54 of the preceding lot (the last winding is drawn with a thick line)
A few seconds in time (approximately the distance of one non-concentric coil, or the distance before and after) between the top 55 of the subsequent lot and the top 55 of the subsequent lot (the frontmost one is drawn with a thick line). ) Usually occurs.

Therefore, between the bottom 54 of the preceding lot and the top 55 of the succeeding lot and other portions, that is, also in the longitudinal direction of the layer thickness coil 52 with respect to the transport direction, the sparse portion and the dense portion related to the number of layers are provided. Relationship has occurred. And, of course, this means that the layer thickness coil 52
, A cooling speed difference is also caused in the longitudinal direction.

However, such a difference in the cooling rate in the longitudinal direction of the layer-thickness coil 52 could not be solved at all even by the above-mentioned various conventional techniques. The present invention has been made in view of the above circumstances, and it is possible to make the cooling rate difference generated in the longitudinal direction of the layer thickness coil uniform so that the wire can be softened and the mechanical properties can be adjusted. It is an object of the present invention to provide a method of cooling a hot-rolled wire so that the wire can be reliably obtained over a wide range and the amount of wire cut-off can be suppressed (ie, the yield can be improved).

[0008]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, in the method of cooling a hot-rolled wire according to the present invention, in the process of placing the hot-rolled wire as a layer-thick coil on a conveyor and transporting it to a cooling section, the bottom of the layer-thick coil which is the preceding lot And the top of the layer-thickness coil to be a subsequent lot. At this time, it is preferable that the effective overlap amount is equal to or more than 1/3 of the coil diameter.

By doing so, in the layer thickness coil,
The relationship between the sparse portion and the dense portion with respect to the number of layers generated in the longitudinal direction can be approximated or eliminated.
Therefore, the cooling rate of the layer thickness coil is made uniform in the longitudinal direction. As a specific operation for generating such an overlap, the winding operation is performed when the bottom of the layer-thickness coil, which is the preceding lot, is wound on the conveyor (that is, placed) by the winding machine, and then the subsequent lot is wound. When the top of the layer-thickness coil to be wound on the conveyor is formed, the conveyance speed may be temporarily reduced on the conveyor side.

As another operation, a step-down portion is provided in the middle of the conveyor, and the bottom of the layer-thickness coil, which is the preceding lot, is shifted from the upper upstream side to the lower-downstream side. There is also a method in which the transfer speed on the lower downstream side is temporarily reduced from the time of transfer to the time when the top of the layer thickness coil as the subsequent lot is transferred to the lower downstream side.

On the other hand, by adopting the endless rolling as hot rolling, the wire and the layer thickness coil are made endless, so that the layer thickness coil is transferred to the cooling section without any gap between lots. You may make it supply continuously.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown schematically in FIG. 2, an example of a wire rod production line is a wire rod 2 rolled by a rolling mill 1.
Is water-cooled by the water-cooling unit 3, and is wound on a conveyor 5 by a winding machine 4 while being placed in a flat state, that is, placed as a layer-thickness coil 6. After being conveyed through a cooling section 7 provided around a predetermined area or the entire area of the conveyor 5, the conveyer 5 has a basic flow of winding it into a coil form by an accumulator 8.

[0013] In such a wire rod production line, the method of cooling a hot-rolled wire rod according to the present invention comprises the winding machine 4
To the accumulator 8, that is, the conveyor 5 and the cooling unit 7.
Is carried out at the time of passing. Note that the structure of the cooling unit 7 is not limited at all, such as whether a slow cooling system or an air cooling system is used, or whether a slow cooling cover or a cover with a heater is provided.

The driving method of the conveyor 5 such as a roller conveyor and a chain conveyor is not limited at all, but the only condition is that the conveyor 5 can be accelerated or decelerated. As shown in FIG. 1, in the present invention, on the conveyor 5 before reaching the cooling unit 7,
On the bottom 10 of the layer thickness coil 6A to be the preceding lot (the last one turn is drawn by a thick line), the top 11 of the layer thickness coil 6B to be the succeeding lot (one foremost end is drawn by a thick line). The overlapped portions 12 (layers overlapping each other) are formed between the layer thickness coils 6A and 6B.

That is, between the layer thickness coils 6A and 6B,
There is no blank space (see reference numeral 56 in FIG. 4). A specific operation for generating the overlap portion 12 is as follows: when the bottom 10 of the layer thickness coil 6A to be the preceding lot is wound on the conveyor 5 (ie, placed) from the winding machine 4. First, the transport speed of the conveyor 5 is reduced.

Note that reducing the transport speed of the conveyor 5 means reducing the transport speed of the conveyor 5 to zero.
That is, the conveyor 5 may be stopped. The standard of this speed reduction is that the top 11 of the layer thickness coil 6B to be a subsequent lot is wound on the conveyor 5 from the winding machine 4 (ie,
This is determined so that a situation in which the bottom 10 of the layer thickness coil 6A to be the preceding lot still remains in the area of the conveyor 5 to which the sheet is to be placed.

When the top 11 of the layer-thickness coil 6B to be a subsequent lot is actually wound on the conveyor 5 from the winding machine 4, a high-speed operation is performed to return the conveying speed of the conveyor 5 to the original speed. To Such an operation is repeated each time the winding machine 4 reaches between the lots.

As a result, when the layer thickness coils 6A, 6B,... Are viewed as a whole, the relationship between the sparse portion and the dense portion with respect to the number of layers occurring in the longitudinal direction can be approximated or eliminated. . Therefore, these layer thickness coils 6A,
6B,... Have uniform cooling rates in the longitudinal direction. Therefore, when the cooling is performed in the cooling unit 7, the wire 2 is sufficiently softened, and when the cooling is performed in the cooling unit 7, the wire 2 has sufficient mechanical properties. Will be obtained.

From the above, the total amount of the wire rod 2 rolled by the rolling mill 1 is reduced by the top 11 and the bottom 10.
In this case, the amount of cut-off can be suppressed, and the yield can be improved. It has been confirmed that the effective length of the overlap portion 12 as the overlap amount is preferably set to be equal to or more than 1/3 of the coil diameter, as is apparent from the results of experiments described later.

As another operation method for forming the overlap portion 12 between the layer thickness coils 6A, 6B,..., As shown in FIG. And the step-down portion 1
5, there is a method in which the transport speed of the lower downstream side 5B is lowered at a predetermined timing from the upper upstream side 5A at a predetermined timing.

That is, when the bottom 10 of the layer thickness coil 6A as the preceding lot is transferred onto the lower downstream side 5B from the upper upstream side 5A on the conveyor 5, first, the transport speed of the lower downstream side 5B is set. Slow down. The standard of this speed reduction is that when the top 11 of the layer thickness coil 6B to be a subsequent lot is transferred from the upper upstream side 5A to the lower downstream side 5B, the area of the lower downstream side 5B to which this is to be placed is placed. Within
The determination is made so as to obtain a situation in which the bottom 10 of the layer-thickness coil 6A as the preceding lot still remains.

When the top 11 of the layer thickness coil 6B to be a subsequent lot is actually transferred from the upper upstream side 5A to the lower downstream side 5B, the transport speed of the lower downstream side 5B is returned to the original speed. To increase the speed. Layer coil 6
As still another operation method for forming the overlap portion 12 between A, 6B,..., The wire rod 2 and the layer thickness coil 6 can be formed by adopting a rolling machine 1 capable of endless rolling of the wire rod 2. A method of continuously supplying the layer-thickness coil 6 to the cooling unit 7 as it is, assuming that there is no blank space between lots in the first place (see reference numeral 56 in FIG. 4), so that it is endless, is also effective. is there.

[0023]

EXAMPLE A wire 2 was produced by using the production line shown in FIG. 2 and performing the first operation method described with reference to FIG. The rolling conditions were as follows: rolling end temperature 950 ° C., wire diameter 1
0 mm and the ring pitch on the conveyor 5 was 10 mm. SCM435 was used as a wire material. Further, the cooling unit 7 employs a cooling unit having a slow cooling cover to perform slow cooling, that is, to cool the wire 2.

In the overlap portion 12 formed between the layer thickness coils 6A and 6B, the wire is manufactured by varying the amount of overlap, and the bottom 10 is formed.
The tensile strength at each predetermined position (the number of turns) near the top and near the top 11 was examined. The experimental results for the bottom 10 are shown in Table 1, and the experimental results for the top 11 are shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

In Tables 1 and 2, the amount of overlap is represented by (3/4) D, (1/1), where the diameter D of one turn of each coil in the layer thickness coils 6A and 6B is "1".
2) It shows that the experiment was performed with five types of D, (1/3) D, 0, and -1D. Here, “0” means that the bottom 10 of the layer-thickness coil 6A and the top 11 of the layer-thickness coil 6B are abutted but not overlapping, and “−1D” means that Thick coils 6A, 6B
This means that a blank space corresponding to one turn of the coil is generated between them (that is, it corresponds to the related art).

As is clear from Tables 1 and 2,
In both the bottom 10 and the top 11, when the amount of overlap is (1/3) D, a suitable softened state is obtained from around 100 to 200 turns, and the amount of overlap is limited to 1D. It is clear that the higher the value of, the better the result.

That is, it means that the cut-off amount of the wire 2 can be suppressed accordingly. By the way, the present invention
It is not limited to the above embodiment. For example, various techniques (eg, Japanese Patent Publication No. 56-28973 and Japanese Patent Publication No. 5
9-52214), it is of course possible to make the overall cooling rate uniform as the layer thickness coil 6.

[0030]

As is apparent from the above description, in the method for cooling a hot-rolled wire according to the present invention, the hot-rolled wire is placed on a conveyor as a layer thickness coil. Since the bottom of the layer thickness coil to be the lot and the top of the layer thickness coil to be the subsequent lot overlap, the sparse part and the dense part with respect to the number of layers in the longitudinal direction of the entire layer thickness coil are similar. Either the state or it has been resolved.

Therefore, the cooling rate of the layer-thickness coil is made uniform in the longitudinal direction, and softening and adjustment of the mechanical properties can be surely obtained in the widest possible range. And improvement in yield).

[Brief description of the drawings]

FIG. 1 is a plan view showing the most important operation state in a method for cooling a hot-rolled wire rod according to the present invention.

FIG. 2 is a schematic view showing an entire line for manufacturing a wire rod by hot rolling.

FIG. 3 is a schematic diagram showing a case where a step-down portion is provided in a middle portion of a conveyor as another operation method for forming an overlap portion between preceding and subsequent lots of a layer thickness coil.

FIG. 4 is a plan view showing a prior-art lot-to-lot lot of a layer thickness coil.

[Explanation of symbols]

 2 Wire rod 4 Winding machine 5 Conveyor 5A Upper upstream 5B Lower downstream 6 Layer coil 6A Layer coil to be the preceding lot 6B Layer coil to be the subsequent lot 7 Cooling unit 10 Bottom of layer coil to be the preceding lot 11 Top 15 layer thickness coil of subsequent lot

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiroyuki Toyama 2nd Nadahama-Higashi-cho, Nada-ku, Kobe-shi, Hyogo F-term in Kobe Steel Works Kobe Works (reference) 4E026 DA01 DA08 4K043 AA02 BA04 BA05 BB06 EA03 EA07 FA03 FA13 GA06

Claims (5)

[Claims] 1. A hot rolled wire (2) is placed on a conveyor (5) as a thick coil (6) and cooled by a cooling unit (7).
Hot rolling, wherein the bottom (10) of the layer thickness coil (6A) serving as the preceding lot and the top (11) of the layer thickness coil (6B) serving as the succeeding lot overlap in the process of transporting to the next step. How to cool the wire. 2. A bottom (10) of a layer thickness coil (6A) to be a preceding lot and a layer thickness coil (6B) to be a subsequent lot.
2. The method for cooling a hot-rolled wire according to claim 1, wherein the amount of overlap with the top (11) is at least 1/3 of the coil diameter. 3. The overlap is formed by the bottom (1) of a layer thickness coil (6A) to be a preceding lot by a winding machine (4).
0) is wound on the conveyor (5), and then the top (11) of the layer thickness coil (6B), which is a subsequent lot, is wound on the conveyor (5). 3. The method for cooling a hot-rolled wire according to claim 1, wherein the conveying speed is reduced. 4. The conveyor according to claim 1, wherein the overlap is a conveyor.
A step-down portion (15) is provided in the middle of the step, and the bottom (10) of the layer-thickness coil (6A) to be the preceding lot is from the upper-stream upstream (5A) to the lower-stream downstream from the step-down (15). When the top (11) of the layer thickness coil (6B), which is a subsequent lot, is transferred to the lower downstream side (5B) from the time of transfer to (5B), the transport speed of the lower downstream side (5B) is changed. The method for cooling a hot-rolled wire according to claim 1 or 2, wherein the cooling is performed by reducing the speed. 5. A hot rolled wire (2) is placed on a conveyor (5) as a thick coil (6) and cooled by a cooling unit (7).
In the process of transporting the wire (2), the wire (2) obtained by performing endless rolling is previously set as the layer thickness coil (6), so that the layer thickness coil (6) is continuously supplied to the cooling unit (7). The method of cooling a hot-rolled wire.