JP2002254101A - Method and apparatus for precisely wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for precisely rolling wire rods capable of securing the level of ±0.1 mm or less dimensional tolerance of diameters and capable of precisely rolling to ±0.05 mm dimensional tolerance in a preferable case in the wire rod whose diameter is 5 to 19 mm by fining wire rod-rolling which produces bar steel. SOLUTION: In the wire rod-rolling to roll a round bar steel by the intermediate line rolling with a block mill and by finish rolling with a sizing mill using a rolling apparatus arranged with a reducing mill (3) just before the sizing mill (2) and after the block mill (1), a rolling more than 14% reduction of area is executed in the reducing mill and immediately after the rolling, rolling rod to be rolled is fed to the sizing mill and a skin pass rolling having 10% or less reduction of area is performed in the sizing mill.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling technique for producing a metal wire rod, typically, a steel bar. According to the present invention, precise rolling with a diameter tolerance of less than ± 0.1 mm in a diameter range of 5 to 19 mm is realized.

[0002]

2. Description of the Related Art In order to manufacture a wire rod having a diameter in a range of several millimeters to several tens of millimeters by rolling a steel rod, it is usual to use a wire rod.
A round bar having a diameter of about 20 mm supplied from the rough rolling process is used as a material, and is rolled as a middle rolling by a block mill having eight rolls, and one or two sizing mills having two rolls are provided. Finish rolling is performed using a table to obtain a product.

[0003] Wire products are required to have fine dimensions depending on the application. For example, in the range of 5 to 10 mm in diameter, 0.5 mm is required.
Products in mm increments are required, and product sizes in 1.0 mm increments are standardized even in the range of 10 to 20 mm in diameter. Naturally, it is desired that the dimensional tolerance for products of each size is also small. However, those that can actually be supplied stably are only those having a dimensional tolerance exceeding ± 0.1 mm and approaching 0.2 mm.

In the wire rod rolling, generally, a rolling roll having a caliber shape as shown in FIG. 1 is used, and upper and lower portions shown by oblique lines in FIG.
In the deformation due to the rolling, the hatched portion in FIG. 2B does not hit the rolling roll, and thus the control of the shape cannot be achieved. This is the main reason why products with small dimensional tolerances cannot be obtained.

[0005] If the amount of reduction is small, the above-mentioned lateral swelling is small, so that the dimensional variation due to the inability to control this portion should be small. In this case, skin pass rolling may be performed toward the final stage of wire rod rolling. However, when hot rolling is performed with a low surface area reduction relative to the steel bar, the crystal grains become coarse due to the strain-induced grain boundary migration, and there is a problem of observing the occurrence of an abnormal structure. Can not do it.

[0006] The applicant carries out rolling at a normal area reduction rate of 10% or more prior to rolling at a low area reduction rate,
We found out that if reduced area rolling is performed while the strain energy due to normal area reduction rolling is maintained, the occurrence of abnormal structures can be avoided. A rolling method has already been proposed (Japanese Patent Laid-Open No. 4-371301). Specifically, in the above-described wire rod rolling by the cooperation of the block mill and the sizing mill, the rolling reduction at the last stage of the block mill or the rolling roll at the first stage of the sizing mill has a surface reduction rate of 10%.
This is a technique in which the above-described normal area-reduction rolling is performed, and while the strain energy due to the rolling is maintained, the reduced area-reduction rolling is performed so that the area reduction is 10% or less. This allows
The dimensional tolerance ± 0.1mm level has been realized.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the dimensional tolerance in wire rod rolling from the above-mentioned ± 0.1 mm level to obtain a level of less than ± 0.1 mm without fail. It is an object of the present invention to provide a rolling method and a rolling device that can reach ± 0.05 mm.

[0008]

According to the present invention, there is provided a precision rolling method for a wire rod in which a metal round bar is rolled by intermediate row rolling by a block mill and finish rolling by a sizing mill. A reducing mill is arranged after the mill and immediately before the sizing mill, and after rolling at a reduction of 14% or more in the reducing mill, the material to be rolled is immediately supplied to the sizing mill. By performing skin pass rolling at a surface reduction rate of 10% or less, a diameter of 5 to 19
This is a precision rolling method for a wire rod which enables manufacture of a wire rod product having a diameter tolerance of less than ± 0.1 mm within a range of mm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The precision rolling apparatus of the present invention for carrying out the above-mentioned method is shown in FIG. 3 as a block mill for intermediate row rolling as shown in FIG. 1) and a wire rod rolling device having a sizing mill (2) for finish rolling as an essential component,
The reducing mill (3) is arranged after the block mill and immediately before the sizing mill, and the reduction in rolling reduction in the reducing mill is 14% or more, and the reduction in rolling in the sizing mill is 10% or less. And the material to be rolled is supplied to the sizing mill immediately after rolling in the reducing mill, so that the diameter is in the range of 5 to 19 mm and the dimensional tolerance of the diameter is ± 0. This is a precision rolling machine for wire rods that enables the manufacture of wire rod products of less than 1 mm.

This apparatus is designed so that the distance between the roll axes of the last roll of the reducing mill and the first roll of the sizing mill is within 2 m, and the speed of the material to be rolled is 10 m / sec or more. preferable. Thereby, prevention of the occurrence of the abnormal tissue is ensured. More preferably, the distance between the roll axes is 1.5 m or less, and the rolling material advance speed is 17 m / sec or more.

Although the number of roll stages of each roll is arbitrary in principle, as for the reducing mill and the sizing mill, as shown in FIG. 3, the former may have two passes, while the latter has four passes. It is desirable. Thereby,
A dimensional tolerance of less than ± 0.1 mm can be reliably achieved. Four passes of the sizing mill can be realized by connecting two 2-pass devices in series. However, in this case, the condition for maintaining the strain energy required between the first mill and the second mill and between the reducing mill and the sizing mill is maintained, and the strain-induced grain boundary migration is prevented. is necessary.

In FIG. 3, the rolling rolls are depicted as being arranged in a horizontal direction, but this is for convenience and is actually a horizontal-vertical combination or an X arrangement.

As described above, the rolling in the reducing mill (3) must be at least 14% in area reduction. By satisfying the condition, a low reduction in the final sizing mill can be achieved without generating an abnormal structure. Although there is no theoretical upper limit for the area reduction rate in the reducing mill, a practical limit based on the relationship between the driving force of the rolling roll and the deformation resistance will be about 40%.

The rolling in the sizing mill (2) is skin-pass rolling, and is performed at a reduction in area of 10% or less. In order to reduce the dimensional tolerance, which is the object of the present invention, it is desirable that the reduction in area of the sizing mill be as small as possible and 10% is the allowable limit, but preferably 5%, based on the above-mentioned principle of the generation of the tolerance in rolling. % Or less, especially 3%
I want to keep it below.

The precision rolling of the present invention has been developed for the most demanding strip steel, and steels which can be conveniently applied include, for example, structural steel and stainless steel. It can be applied to metal materials.

[0016]

EXAMPLE Using the rolling apparatus shown in FIG. 3, a material having a diameter of 20 mm supplied from a rough rolling mill roll was rolled to produce a wire rod product having a diameter of 8.0 mm. The material to be rolled out of the block mill (1) has a diameter of 9.4 mm, and is reduced to 8.4 mm in a reducing mill (3).
The pressure was reduced to 8.1 mm before the sizing mill (2), and finally 8.0 after the sizing mill (2).
mm to obtain a product. The area reduction rate is 20% for the reducing mill, 7% for the former stage of the sizing mill, and 2.5% for the latter stage of the sizing mill.

The dimensional tolerance of the obtained wire product is a length 30
± 0.06 on average at 50 locations equally dividing a 00m wire rod
mm. The inside of the cut wire was observed under a microscope, and no abnormality was found in the tissue.

[0018]

According to the present invention, a reducing mill is disposed between a block mill and a sizing mill, and by appropriately distributing the rolling reduction of the latter, a diameter of 5 to 19 is achieved.
mm wire with a diameter tolerance of less than ± 0.1 mm,
In a preferred case, it is possible to provide a product reduced to a point approaching ± 0.05 mm.

In the case where the dimensional tolerance of the wire is extremely tight, for example, ± 0.05 to 0.03 mm, cold drawing using a die is conventionally performed after rolling (if necessary, further annealing is also required). ) Had to do it. However, the dimensional tolerance requirements are not so demanding, and
If about 0.5 to 0.07 mm is acceptable, the product obtained by rolling by the method of the present invention can be used as it is,
The drawing step can be omitted. This, of course, greatly contributes to cost reduction.

[Brief description of the drawings]

FIG. 1 is a front view showing a caliber shape of a rolling roll used for wire rod rolling.

FIG. 2 is a cross-sectional view of a wire rod showing a state of reduction when the wire rod is rolled by the rolling roll of FIG. 1, wherein a hatched portion of A indicates a portion to be crushed, Shown respectively.

FIG. 3 is a conceptual diagram showing a configuration of a precision rolling device of the present invention and a cross-sectional shape of a wire rod discharged from each rolling roll.

[Explanation of symbols]

 1 block mill 2 sizing mill 3 reducing mill

Claims (5)

[Claims] In a wire rod rolling method for rolling a metal round bar by intermediate row rolling by a block mill and finish rolling by a sizing mill, a reducing mill is disposed after the block mill and immediately before the sizing mill. Immediately after rolling at a reduction rate of 14% or more in a reducing mill, the material to be rolled is supplied to a sizing mill, and skin pass rolling at a reduction rate of 10% or less is performed in the sizing mill, whereby a diameter of 5 mm is obtained. A precision rolling method for a wire rod, which is capable of manufacturing a wire rod product having a diameter tolerance of less than ± 0.1 mm in a range of about 19 mm. 2. The precision rolling method according to claim 1, wherein the process from the end of the rolling in the reducing mill to the start of the skin pass rolling in the sizing mill is performed within 0.2 seconds. 3. A wire rolling apparatus including a block mill for intermediate row rolling and a sizing mill for finish rolling as an essential component, and a reducing mill immediately after the block mill and immediately before the sizing mill. And reducing the rolling reduction rate in the reducing mill by 14%
As described above, the reduction rate of the rolling in the sizing mill is set to 10% or less by skin pass rolling, and the material to be rolled is supplied to the sizing mill immediately after rolling in the reducing mill. And a precision rolling device for a wire rod capable of manufacturing a wire product having a diameter tolerance of less than ± 0.1 mm. 4. The distance between the roll axis centers of the last roll of the reducing mill and the first roll of the sizing mill is 2 m.
4. The precision rolling apparatus according to claim 3, wherein a traveling speed of the material to be rolled is set to 10 m / sec or more. 5. The precision rolling apparatus according to claim 3, wherein the reducing mill comprises two-pass rolls, and the sizing mill comprises four-pass rolls.