JP5874565B2 - Rolling equipment and wire rod rolling method - Google Patents

Description

  The present invention relates to a rolling equipment and a wire rod rolling method for rolling a billet as a material to be rolled in a stepwise manner to finish a wire rod as a final product.

Conventionally, when a wire is manufactured by rolling, a billet (rolled material) heated in a heating furnace is rolled by a roughing mill and an intermediate rolling mill, and then rolled by a finish rolling mill (block mill) to obtain a desired wire. The wire is finished with a diameter.
Moreover, after rolling with a finishing mill (block mill), it may be further rolled with a final finishing mill (sizing mill) (for example, refer patent document 1).

  In recent years, there is a demand for a wire having a small wire diameter. In order to meet this requirement, it is necessary to reduce the size of the material to be rolled into the block mill. To that end, the billet size must be reduced, or reduction by a roughing mill or intermediate rolling mill can be performed. It is necessary to increase the size of the material to be rolled into the block mill and reduce the size. In addition, when the size of the material to be rolled cannot be reduced, the number of finish rolling mills and final finishing rolling mills must be increased so that a wire having a small wire diameter can be rolled.

JP 2006-289436 A

However, reducing the size of the material to be rolled requires time and effort for that purpose. In addition, in order to reduce the size of the material to be rolled into the block mill by increasing the reduction with a roughing mill or an intermediate rolling mill, a large-scale replacement of the roll hole mold of the rolling mill is required for that purpose. The preparation period and costs cannot be ignored. Furthermore, if these preparation periods are prolonged, productivity may be greatly hindered. Further, when the number of finish rolling mills and final finish rolling mills is increased, the cost of equipment enhancement increases.
Therefore, the present invention, when demanding a wire with a small wire diameter, can be transferred by utilizing existing equipment, shortening the period during the transition, rolling equipment that can reduce the cost associated with the transition, and It is in providing the rolling method of a wire.

In order to solve the above problems and achieve the above object, one aspect of the present invention has the following configuration.
That is, the rolling equipment according to one aspect of the present invention is a rolling equipment that rolls a material to be rolled in stages, and finishes the wire as a final product, and rolls the material to be rolled into a steel bar having a circular cross section. A first rolling mill, a second rolling mill for rolling the steel bar rolled by the first rolling mill into a rectangular bar having a rectangular cross-sectional shape and rounded corners of the rectangular shape, and the second rolling mill. A third rolling mill that is a block mill that rolls a square bar rolled by a rolling mill into a wire having a circular cross section.
Here, the second rolling mill is preferably a 4-roll mill, and the rolling reduction is preferably 25% or less.

Further, the second rolling mill includes a four-roll first stand into which the steel bar is introduced, and a four-roll second stand disposed at the rear stage of the first stand, and each roll of the second stand The hole mold surface is flat and is rolled into the square bar by the second stand.
Further, the method of one embodiment of the present invention is a method of rolling a wire that rolls the material to be rolled in stages, and finishes the wire that is the final product, and the material to be rolled is rolled into a steel bar having a circular cross section. Using a block mill, a second step of rolling the steel bar rolled in the first step into a square bar having a rectangular cross-sectional shape and rounded corners of the rectangle, And a third step of rolling the square bar rolled in the second step into a wire having a circular cross section.
Here, in the said 2nd process, it is preferable to roll using a 4 roll mill, and also it is preferable that a rolling reduction is 25% or less.

As described above, in one aspect of the present invention, the cross-sectional shape is a rectangle, and each rectangle of the rectangle is rolled into a square bar with a rounded shape. It was made to roll.
For this reason, in one aspect of the present invention, the size of the material to be rolled (billet) is not reduced in response to the demand for a wire having a small wire diameter, and the hole of a rolling mill other than the second rolling mill or the block mill is used. It is possible to roll a wire having a small wire diameter without changing the mold and further without the need for a finishing mill or a final finishing mill.
Therefore, according to one aspect of the present invention, when requesting a wire rod having a small wire diameter, the existing equipment can be utilized as much as possible, and the period for the migration can be shortened, and the costs associated with the migration can be reduced. be able to.

It is a figure which shows schematic structure of the rolling mill applied to embodiment of this invention. It is a figure which shows the structural example of 4 rolls of the 1st stand and 2nd stand applied to a wire intermediate rolling mill. It is explanatory drawing for demonstrating a rolling reduction. It is explanatory drawing explaining the flow of rolling of embodiment of this invention. It is explanatory drawing for demonstrating the biting in the case of rolling from a circular cross section to a circular cross section. It is a figure which shows the rolling state in the 2nd rolling mill in embodiment of this invention.

An embodiment of the rolling equipment of the present invention will be described with reference to FIG.
(Composition of rolling equipment)
As shown in FIG. 1, the rolling equipment to which the embodiment of the present invention is applied is capable of rolling a billet, which is a material to be rolled, in stages, and finishing it into a bar or wire as a final product.
For this reason, the rolling mill which concerns on this embodiment is provided with the heating furnace 1 which heats a to-be-rolled material, as shown in FIG. And in order to roll a to-be-rolled material in steps and finish to the steel bar which consists of the target diameter, the 1st conveyance path 2 of the to-be-rolled material is extended from the heating furnace 1, The 1st conveyance path 2 includes A rough rolling mill 3, an intermediate rolling mill 4, and a 4 roll mill 6 are arranged in this order.

In addition, in order to finish the material to be rolled out of the 4-roll mill 6 in stages and finish it into a wire having a preset target diameter (wire diameter), a second conveyance path 7 is provided in the middle of the first conveyance path 2. It is connected. Further, a block mill 8 and a wire rod 4 roll mill 10 are sequentially arranged in the second transport path 7.
Here, the rough rolling mill 3 and the intermediate rolling mill 4 are the first rolling mill 5 that rolls into a steel bar having a circular cross section, and the 4-roll mill 6 is a bar steel rolled by the first rolling mill 5 and has a rectangular cross section. Thus, the second rolling mill 6 performs rolling into a rectangular bar having a rounded corner.

The heating furnace 1 heats the material to be rolled to a predetermined temperature set in advance. The rough rolling mill 3 and the intermediate rolling mill 4 roll the material to be rolled heated in the heating furnace 1 step by step to finish a steel bar having a preset target diameter. One rolling mill 5 is formed.
The 4-roll mill 6 rolls a steel bar having a circular cross section discharged from the first rolling mill 5 into a square bar having a square cross section of a rectangle such as a square or rhombus and rounded corners of the rectangle. 2 rolling mills are formed. The rolled square bar is supplied to the block mill 8 after passing through the second conveyance path 7.

  The block mill 8 is configured to roll the supplied square bar into a wire having a circular cross-sectional shape. The block mill 8 consists of 10 stands of 2 rolls, for example. The wire 4 roll mill 10 rolls the wire rolled by the block mill 8 to a wire having a preset target diameter.

(Configuration of second rolling mill (4 roll mill))
Next, a specific configuration of the 4-roll mill 6 will be described with reference to FIG.
The 4-roll mill 6 is arranged at the rear stage of the first stand 20 of four rolls having the rolls 21 to 24 as shown in FIG. 2 (A), and as shown in FIG. 2 (B). 4 roll 2nd stand 30 provided with rolls 31-34.
As shown in FIG. 2A, the rolls 21 to 24 are arranged so that the pair of upper and lower rolls 21 and 22 and the pair of left and right rolls 23 and 24 are orthogonal to each other in the same vertical plane. Is arranged. And the steel bar 25 rolled with the 1st rolling mill 5 is introduce | transduced into the rolls 21-24. Each die surface (rolling surface) of the rolls 21 to 24 is formed to be curved so that the steel bar 25 can be easily bitten (see FIG. 2A).

As shown in FIG. 2 (B), the rolls 31 to 34 are arranged such that the roll axes (not shown) of the pair of rolls 31 and 32 and the pair of rolls 33 and 34 are orthogonal to each other in the same vertical plane. Yes. And the steel bar discharged from the 1st stand 20 is introduce | transduced into the rolls 31-34, and this introduce | transduced steel bar is a square bar 35 in which the cross-sectional shape was a square and each corner of the square was rounded. It is supposed to be rolled. Each hole type surface of the rolls 31 to 34 is formed flat as shown in the figure, and the rolls 31 to 34 are flat rolls.
Here, the rolls 21 to 24 and the rolls 31 to 34 can adjust (set) the roll gap to an arbitrary value.

Next, the rolling reduction of the 4-roll mill 6 configured as described above will be described with reference to FIGS. 2 and 3.
The 4-roll mill 6 includes a first stand 20 having the rolls 21 to 24 shown in FIG. 2A and a second stand 30 having the four rolls 31 to 34 shown in FIG. And the steel bars 25 rolled by the first rolling mill 5 are introduced into the rolls 21 to 24 of the first stand 20, and when the steel bars 25 are discharged from the rolls 31 to 34 of the second stand 30, the steel bars 25 have a cross-sectional shape. A square bar 35 is obtained by rounding each corner of the square.

Therefore, the rolling reduction S of the 4-roll mill 6 is obtained by the following equation (1).
S = [(D0−D) / D0] × 100 [%] (1)
Here, D0 is the diameter (diameter) of the steel bar 25 as a base material, and D is the distance (gap) between the opposing rolls of the rolls 31 to 34 of the second stand 30 (see FIG. 3).
And the range of the rolling reduction S of the 2nd stand 30 of the 4 roll mill 6, ie, the 4 roll rolling machine with which the flat roll was incorporated, is set so that a to-be-rolled material can be rolled from a circular cross section to a square cross section. The first stand 20 of the 4-roll mill 6 has a pinch roll-like role for feeding the material to be rolled to the second stand 30.

(Rolling wire method)
Next, a method for rolling the billet as a material to be rolled in a stepwise manner by applying the rolling equipment shown in FIG. 1 to finish the wire with a target diameter set in advance as a final product will be described with reference to the drawings. .
The material to be rolled is heated to a predetermined temperature set in advance in the heating furnace 1, and the heated material to be rolled is supplied to the roughing mill 2. The supplied material to be rolled is rolled in stages by a first rolling mill 5 comprising a rough rolling mill 3 and an intermediate rolling mill 4 (first step), and when discharged from the first rolling mill 5, FIG. The cross section shown is a circular steel bar 25. The steel bar 25 has a diameter D0 as shown in FIG. 4, and the diameter D0 is, for example, 17 [mm].

  The steel bar 25 discharged from the first rolling mill 5 is supplied to a second rolling mill (4 roll mill) 6. In the second rolling mill 6, the supplied steel bar 25 is rolled into a square bar 35 having a square cross section and rounded corners of the square (second step). The cross-sectional shape of the square bar 35 is, for example, as shown in FIG. 4, and the distance L between the opposing surfaces of the square bar 35 is, for example, 13.5 [mm].

  Here, in the second rolling mill 6, since the steel bar 25 is rolled into the square bar 35, the rolling reduction can be increased, and the cross-sectional area of the material to be rolled on the entry side of the block mill 8 can be reduced. Moreover, in the 2nd rolling mill 6, in order to make the steel bar 25 into the square bar 35, it was made to use 4 rolls in the 2nd stand 30 instead of a combination of 2 rolls. For this reason, the cross-sectional shape of the square bar 35 discharged from the four rolls of the second stand 30 is a square, and the four corners of the square are rounded (see FIG. 3).

  The rolled square bar 35 passes through the second conveyance path 7 and is supplied to the block mill 8. At this time, as described above, the entrance-side cross section of the block mill 8 is not an ordinary circular shape but an angular cross-sectional shape, but the block mill 8 can be bitten into the most upstream mill without any problem. Further, since the corners of the square cross-sectional shape are rounded, the occurrence of folding wrinkles after rolling by the block mill 8 can be prevented. In the block mill 8, the supplied square bar 35 is rolled into a wire 40 having a circular cross section (see FIG. 4). The diameter D1 of the wire 40 is, for example, 5.0 [mm].

  The rolled wire 40 is supplied to the wire 4 roll mill 10. In the wire rod 4 roll mill 10, the wire rod 40 is rolled into a wire rod 50 having a circular cross section (see FIG. 4). The rolling reduction of the wire rod 4 roll mill 10 can be adjusted, and the diameter D2 of the wire 50 on the exit side of the wire rod 4 roll mill 10 is, for example, 4.0 to 4.5 [mm]. The wire 50 thus obtained becomes a final product that is further cooled to ensure the quality.

Here, the reason why the second rolling mill 6 performs rolling into a rectangular cross-sectional shape is as follows.
That is, when using existing equipment such as the block mill 8 and the wire rod 4 roll mill 10, it is difficult to largely change the overall rolling reduction of the block mill 8, for example. In order to deal with the manufacture of a wire rod having a small wire diameter using such a block mill 8 or the like, it is necessary to reduce the cross-sectional area of the material to be rolled on the entrance side of the block mill 8. For example, in order to roll a wire having a final wire diameter of 4.0 to 4.5 mm, a case where the cross-sectional shape of the material to be rolled on the entrance side of the block mill 8 needs to be 15 mmφ is considered. . At that time, when the minimum dimension that can be rolled by the first rolling mill 5 is 17 mmφ, the second rolling mill 6 needs to roll from 17 mmφ to 15 mmφ. In this case, the cross-sectional reduction rate in the second rolling mill 6 is [π × (17/2) ² −π × (15/2) ² ] / [π × (17/2) ² ] × 100 = 22. 1%.

  At this time, when rolling from a steel bar 25 having a circular cross section to a steel bar 350b having a circular cross section with a cross-section reduction rate of 22.1%, the case of a four roll mill 6 including a first stand 20 and a second stand 30 is taken as an example. In the first stand 20, as shown in FIG. 5A, the rolls 210 and 220 are squeezed in the vertical direction and the rolls 230 and 240 are squeezed in the horizontal direction. ) Rolling is performed so that the portion squeezed in the region X) shown in FIG. Next, in the second stand 30, as shown in FIG. 5B, the steel bar 350 a obtained by rolling the first stand 20 is rolled down in the 45 ° direction by the rolls 310 and 320 and the rolls 330 and 340, respectively. In the central portion in the width direction of each roll (region Y shown in FIG. 5B), after rolling with the first stand 20, an arc having a diameter of 15 mm is formed with respect to a portion that is not an arc, Finally, it is rolled into a steel bar 350b having a circular cross section of 15 mmφ. However, when the material to be rolled is twisted (also referred to as toppling) in rolling with the second stand 30, as shown in FIG. 5C, each material of the material of the second stand 30 originally of the material to be rolled (bar 350a) is formed. The portion to be rolled at the center in the width direction of the roll shifts to the end in the width direction of each roll, and in this case, adjacent rolls (roll 310 and roll 340, roll 340 and roll 320, roll 320 and roll 330). , The material 110 to be rolled out into the space 300 between the roll 330 and the roll 310) occurs, or the cross-sectional area of the rolled steel bar 350b changes in the longitudinal direction. Then, when the rolled material 350b in which the biting 110 or the cross-sectional area has changed in the longitudinal direction is rolled by the subsequent block mill 8, the portion of the biting 110 is folded into a wrinkle or rolled by the block mill 8. Later, the cross-sectional area changes in the longitudinal direction.

  As the material to be rolled becomes thinner, the contact area between each roll of the second stand 30 and the material to be rolled (steel bar 350a) becomes smaller, and further, the first stand and the second stand with respect to the diameter of the material to be rolled. Since the distance between the stands (distance between the stands / rolled material diameter) becomes long, the twist between the first stand 20 and the second stand 30 is likely to occur. A cross-sectional area change in the longitudinal direction is likely to occur.

  Therefore, the inventor makes the hole mold surface of each roll of one stand of the four-roll mill 6 flat and makes the hole mold formed by these hole mold surfaces rectangular, and from this circular stand to the rectangular cross section only with this one stand. It has been found that a large reduction rate of the cross-section can be secured without causing a large biting 110 by rolling to a large width. Specifically, the hole mold surface of each roll of the second stand 30 of the 4-roll mill was made flat, and the second stand 30 was rolled from a circular cross section to a rectangular cross section. The first stand 20 was not rolled, and each roll of the first stand 20 served as a pinch roll for feeding the material to be rolled to the second stand 30.

That is, in order to roll into a wire having a diameter of 4.0 to 4.5 mm, the entrance side of the block mill 8 needs to have a diameter of 15 mm in the case of a circular cross section, and the cross sectional area at this time is 176.7 mm ² . When a cross-sectional area equivalent to this is a square cross-section, the length of one side is 13.3 mm. Therefore, when a steel bar having a circular cross section of 17 mmφ is used as a material to be rolled, rolling is performed to a square cross section having a side length of 13.3 mm by the second stand 30 of the above-described 4-roll mill 6, and the bite shown in FIG. It was possible to perform rolling without generating the discharge 110. In this case, the biting 110 does not occur, as shown in FIG. 6, where the amount of reduction by the roll surface near the corner 100 is very small, or the vicinity of the corner 100 is hardly reduced by the roll surface. This is probably due to this.

  However, when rolling a steel bar having a rectangular cross section into a wire having a circular cross section with the block mill 8, when the corners of the rectangular cross section are squeezed by the roll surface of the block mill 8, a folding wrinkle is generated. There was concern. Actually, when a steel bar having a rectangular cross-section with a sharp corner was rolled into a wire having a circular cross-section by the block mill 8, folds were frequently generated. Therefore, when the corners were rounded and rolled into a wire having a circular cross section by the block mill 8, the generation of folding wrinkles could be prevented. And it is especially effective to use a 4-roll rolling mill as the second rolling mill 6 in order to roll into a square bar with rounded corners. That is, in the 4-roll rolling mill, as shown in FIG. 6, the four corners 100 are all formed without contacting the roll surface, and thus have a rounded shape. Therefore, in order to prevent the above-mentioned folding wrinkles from occurring, the second rolling mill is a four-roll rolling mill in order to make the corners of the rectangular cross section rounded.

  Here, even if a four-roll mill incorporating a roll with a flat pressed surface is used, if the rolling reduction S according to the above equation (1) is too large, the above-described biting 110 will occur, so the biting will not occur. It is necessary to set a rolling reduction that does not occur. Further, by conducting a test in consideration of the biting property of the square bar 35 discharged from the 4-roll mill 6 into the block mill 8 and the quality of the wire obtained on the exit side of the wire 4-roll mill 10, a round cross-section to a rectangular cross-section is performed. It was confirmed that if the rolling reduction of the 4-roll mill 6 that performs rolling is 25% or less, a thin wire having a diameter of up to 4.0 mmφ can be produced without problems.

(Effect of embodiment)
In this embodiment, a 4-roll mill 6 is arranged between the intermediate rolling mill 4 and the block mill 8 in order to roll the material to be rolled stepwise and finish it into a wire having a target diameter (wire diameter). I made it. The 4-roll mill 6 rolls the steel bar 25 having a circular cross-sectional shape into a square bar 35 having a square cross-sectional shape and rounded corners. Further, the 4-roll mill 6 includes two stands 20 and 30 of 4 rolls, and the stand 20 acts as a pinch roll for feeding the steel bar 25 to the stand 20 without rolling, and the stand 30 has its rolling reduction rate. 25% or less.
Thereby, in this embodiment, when the square bar 35 discharged | emitted from the wire intermediate rolling mill 6 is bitten by the first roll of the block mill 8, the biting property is improved, and the wire 4 roll mill 10 It was confirmed that the quality of the rolled wire 50 can be secured.

There is no need to reduce the size of the material to be rolled (billet), no need to change the hole shape of rolling mills other than the 4-roll mill and block mill, and the need to strengthen the finishing mill and final finishing mill In addition, it is possible to roll a wire having a small wire diameter.
Therefore, according to this embodiment, when requesting a wire rod having a small wire diameter, the existing rolling mill can be utilized as much as possible, the period during the migration can be shortened, and the costs associated with the migration can be reduced. Can do.

(Other embodiments)
In the above embodiment, a 4-roll mill is used as the second rolling mill 6 used in the second rolling process, but in the second rolling process, the cross-sectional shape is rectangular, and the rectangular corners are rounded. As long as it can be rolled into a square rod, it is not always necessary to use a four-roll rolling mill, and for example, a two-roll rolling mill having two pairs of rolls having a rectangular hole shape may be used.
In the above embodiment, after rolling in a block mill (third rolling mill), the wire is further rolled to the final finished diameter using a 4-roll mill. A wire 4 roll mill is not necessarily required as long as it can be rolled to the finished diameter.

DESCRIPTION OF SYMBOLS 1 ... Heating furnace 2 ... 1st conveyance path 3 ... Rough rolling mill 4 ... Intermediate rolling mill 5 ... 1st rolling mill 6 ... 2nd rolling mill (4 roll mill)
7 ... 2nd conveyance path 8 ... Block mill 10 ... Wire rod 4 roll mill 20, 30 ... Stands 21-24, 31-34 ... Roll 25 ... Steel bar 35 ... Each bar 40, 50 ... wire rod 100 ... corner 110 ... biting out

Claims (2)

Rolling equipment that rolls the material to be rolled in stages and finishes it into the final product,
A first rolling mill for rolling the material to be rolled into a steel bar having a circular cross section;
A second rolling mill for rolling the steel bar rolled by the first rolling mill into a rectangular bar having a rectangular cross-sectional shape and rounded corners of the rectangle;
A third rolling mill which is a block mill for rolling the square bar rolled by the second rolling mill into a wire having a circular cross section;
A rolling facility comprising: A rolling method of a wire rod that rolls the material to be rolled in stages and finishes it into a wire rod that is a final product,
A first step of rolling the material to be rolled into a steel bar having a circular cross section;
A second step of rolling the steel bar rolled in the first step into a square bar having a rectangular cross-sectional shape and rounded corners of the rectangle;
Using a block mill, a third step of rolling the square bar rolled in the second step into a wire having a circular cross section;
A method for rolling a wire, comprising:

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