JP4504242B2 - Wire rod rolling method - Google Patents

Description

  The present invention relates to a rolling method for realizing stable high dimensional precision rolling by preventing the occurrence of surface flaws and cobbles in the finish rolling process of wire rods and steel bars.

  As shown in FIG. 5, the billet (rolled material) heated by the heating furnace 1 is composed of a rough rolling mill 2, an intermediate wire rod and bar steel (burn-in coil, hereinafter collectively referred to as a wire rod). After being rolled by the rolling mills 3 a and 3 b, it is rolled by the finish rolling mill 4 and the final finishing rolling mill 5, finished to a desired wire diameter, and wound by the winder 6 in a loop shape. A block mill is used for the finish rolling mill 4 and a sizing mill (sizing block mill) is used for the final finish rolling mill 5. For example, when the finish wire diameter is 5.5 mm, the exit side of the finish rolling mill 4 is used. 60 m / s, and high-speed rolling of about 100 / s is performed on the exit side of the final finish rolling mill 5.

  As is well known, the block mill is a compact rolling mill in which a plurality of roll stands are normally driven by a common drive device equipped with a variable speed motor, and the roll speed of each stand cannot be individually adjusted in this block mill. Therefore, a roll hole type design, that is, a pass schedule is designed so that tension is generated between the roll stands. The perforated design that generates tension between the roll stands in this block mill generates vibrations in the material to be rolled when the compressive force acts on the material to be rolled between the stands, and comes into contact with the guides on the entry and exit sides of the roll. In order to avoid the occurrence of surface flaws and the occurrence of cobbles by the opening of the roller gap of the roller guide for holding the material to be rolled on the roll entry side due to vibration.

In recent years, in order to improve product dimensional accuracy (finishing wire diameter dimensional accuracy), as shown in FIG. 1, a final finish rolling mill is provided downstream of a finish rolling mill 4 (block mill) conventionally employed. No. 5, a rolling mill (sizing mill) equipped with a sizing (precision rolling) mechanism that enables rolling with a reduced area ratio has been arranged. For example, in Patent Document 1, as shown in FIG. 6, finish rolling in which a plurality of rolling mills 14 including a pair of rolling rolls 12 and 12 facing each other across a pass line of a material 11 to be rolled is arranged in a multistage manner. On the rear side (downstream side) of the machine (block mill) 16, the front stage side rolling mill 18 composed of roll stands 26 and 28 having a pair of rolling rolls 24 and 24, as well as a pair of rolling rolls 24 and 24 are provided. A final finish rolling mill (sizing mill) 22 is arranged in which the latter-stage rolling mills 20 including the roll stands 30 and 32 are arranged in tandem. Then, in this final finish rolling mill (sizing mill) 22, in the former stage rolling mill 18, rolling is performed so that the area reduction rate is 16% or more and the dimensional tolerance is within ± 1%. Discloses a precision rolling method in which reduced area reduction rolling is performed so that the area reduction ratio is 10% or less. Further, in Patent Document 2, as shown in FIG. 7, a block mill type multi-stage roll stand 31, 32, 33 that is commonly driven by an electric motor 35, 36, 37, an entrance side of the roll stand 31 before finishing, the roll Laser Doppler speedometers 38, 39, and 40 are arranged between the stands 31 and 32 and on the exit side of the final finishing roll stand 33, respectively, and the rolled side on the insertion side and extraction side of the multi-stage roll stands 31, 32, and 33 is rolled. A technique is disclosed in which the speed of the material 11 is measured and a command is issued from the controller 41 to which the speed information is input to the motors 35, 36, and 37 to control the roll rotation speed of the roll stands 31, 32, and 33. . Based on the measured speed of the material 11 to be rolled, accurate speed control is always possible even if there is roll wear or change of the steel material of the material to be rolled, and it has a beneficial effect on improving the quality of the wire rod and bar steel. Is stated.
JP 2004-358515 A JP 2004-74228 A

  When a sizing mill is arranged as the final finish rolling mill, the number of reductions in the cross section in the final finish rolling mill is usually changed with respect to one rolled material size (wire diameter) on the exit side of the finish rolling mill 4. By rolling products with such finishing wire diameters, integration of pass schedules that expand the common use of roll hole molds up to the exit side of the finish rolling mill 4 is performed. For this reason, compared with the case of the final finish rolling mill 5, the rolling tonnage per roll perforation of the final pass of the finish rolling mill 4 is significantly increased. The size of the rolled material on the delivery side gradually increases as the rolling tonnage increases.

  When the dimension of the rolled material on the exit side of the finish rolling mill 4, that is, the dimension of the rolled material on the entry side of the final finish rolling mill 5 is increased, the dimension of the rolled material (finished wire diameter) on the exit side of the final finish rolling mill 5 is also usually increased. growing. However, when a sizing mill is disposed in the final finish rolling mill 5, the sizing mill only performs rolling with an extremely reduced surface area that only adjusts the cross-sectional shape of the rolled material. Even if the dimensions vary, the finished wire diameter, that is, the dimensional accuracy of the product does not vary greatly. In addition to hole wear, the rolling material dimensions on the entry side of the final finish rolling mill 5 vary even if the type of rolled material (steel type) and rolling temperature change. There is no significant variation in dimensional accuracy. Thus, it is one advantage of the sizing mill that fluctuations in the rolling material dimensions on the entry side of the final finish rolling mill 5 do not greatly affect the dimensional accuracy of the product.

  However, fluctuations in the size of the rolled material on the entry side of the final finish rolling mill have a great influence on the tension between the roll stands in the final finish rolling mill. Product dimension management is performed by measuring the dimensions of the rolled material (finished wire diameter) on the delivery side of the final finish rolling mill. If the finished wire diameter is within the target dimensional accuracy, the final finish rolling mill Normally, adjustment of the roll gap and the size of the rolled material on the entry side is not performed. For this reason, in the sizing mill, even if the dimensions of the entry side rolling material of the final finish rolling mill fluctuate, the above adjustment is often not performed because the fluctuation of the exit side rolling material dimension (product dimension) is small. As described above, surface tension and cobble may occur due to improper inter tension.

  In the precision rolling method disclosed in Patent Document 1, the tension between the stands (between the rolling mills) between the front-side rolling mill 18 and the rear-side rolling mill 20 of the final finish rolling mill 22 shown in FIG. Nothing is listed. Even if the roll tension is appropriate at the initial setting stage, the tension between the stands also fluctuates due to the dimensional fluctuation of the material to be rolled on the entry side of the final finish rolling mill 22, so The risk of occurrence will not be resolved. Moreover, in the control method of the rolling apparatus disclosed in Patent Document 2, the roll stands of the multi-stage roll stands 31, 32, 33 are commonly driven by the electric motors 35, 36, 37, respectively, and the roll rotation of each roll stand is performed. Since the ratio of the numbers is fixed in advance by the speed increasing ratio (the ratio at which the rolling speed increases as the cross-section decreases by rolling), based on the measured speed of the material to be rolled by the Doppler speedometers 38, 39, and 40. Even if the roll rotation speed is controlled for each of the multi-stage roll stands 31, 32, 33 via the controller 41, the inside of the multi-stage roll stands 32, 33 corresponding to the former stage rolling mill and the latter stage rolling mill of the final finish rolling mill The number of rotations of each of the roll stands 32a, 32b, 33a to 33d cannot be individually controlled. Therefore, the tension between these stands can also be controlled. Not come. For this reason, as described above, it is impossible to avoid vibrations due to dimensional fluctuations of the rolled material on the entry side or the entry side of the rear side rolling mill of the final finish rolling mill, and generation of surface flaws, cobbles, etc. The risk of inviting will not be resolved.

  The present invention has been made in view of the above-mentioned problems, and its problem is to improve the dimensional accuracy of the product by providing a final finish rolling mill (sizing mill) after the finishing mill (block mill). Providing a method of rolling a wire that can stably realize high dimensional accuracy by preventing the occurrence of surface flaws and cobbles in the rolling process in the final finish rolling mill when the wire rod is placed and rolled. It is to be.

  In order to solve the above problems, the present invention employs the following configuration.

That is, the method for rolling a wire according to claim 1 is a method for rolling a wire in a hot rolling line equipped with a final finish rolling mill on the rear stage side of the finish rolling mill, and is the same as that of the final finish rolling mill. In rolling in a finish hole mold, the final ratio of the final finish rolling mill is maintained at a constant ratio V ₁ / V ₀ between the rolling speed V _{0 on the} entry side and the rolling speed V ₁ on the exit side between the materials to be rolled, The present invention is characterized in that fluctuations in the cross-section reduction rate of the material to be rolled in the final finish rolling mill are suppressed.

In the sizing mill installed as the final finish rolling mill, only rolling with an extremely reduced surface area is performed to adjust the cross-sectional shape of the material to be rolled, so even if the dimensions of the material to be rolled on the entry side fluctuate. The finished wire diameter, i.e. the dimensions of the product, hardly changes. This means that the reduction in area of the material to be rolled in the final finish rolling mill has changed. When such a reduction in the area reduction occurs, the tension between the roll stands in the final finish rolling mill is not good. As described above, surface flaws and cobbles may occur as described above. The reduction of area R of the final finish rolling mill, by using the cross-sectional area A ₀ and A ₁ of the rolling mill inlet side and outlet side of the rolled _{material, R = (A 0 -A 1} ) / A 0 = 1 Although it is calculated by -A ₁ / A ₀ , it is difficult to measure the cross-sectional area of the material to be rolled online. Now, assuming that the cross-sectional areas of the material to be rolled at the entrance and exit of the rolling mill are A ₀ and A ₁ , A ₀ × V ₀ = A ₁ × V ₁ , that is, A ₀ / A ₁ = V ₁ / V ₀ is established. Accordingly, the area reduction ratio R is R = 1−V ₁ / V ₀ , and the rolling speeds on the entrance side and the exit side of the rolling mill, that is, the speeds V ₀ and V ₁ of the material to be rolled are obtained, and the ratio V ₁ / V If V ₀ is made constant, the area reduction rate in the final finish rolling mill can be made constant, that is, fluctuations in the area reduction rate can be suppressed, and vibration of the material to be rolled can be prevented. The target speed ratio for making the speed ratio V ₁ / V ₀ constant can be set in advance from the hole rolling schedule.

The wire rod rolling method according to claim 2 adjusts the cross-sectional area of the material to be rolled on the entry side of the final finish rolling mill by adjusting the roll gap of the finish rolling mill, so that the speed ratio V ₁ / V ₀ is kept constant.

In order to control the speed ratio V ₁ / V _{0 to} be constant, a relational expression of V ₁ / V ₀ = A ₀ / A ₁ is established, and the cross-sectional area of the material to be rolled on the outlet side of the final finish rolling mill Since A ₁ is constant, it can be seen that the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finish rolling mill may be adjusted. The entry side sectional area A ₀ of the material to be rolled can be adjusted by adjusting the roll gap of the finish rolling mill.

The method for rolling a wire according to claim 3 adjusts the cross-sectional area of the material to be rolled on the entry side of the final finish rolling mill by adjusting the roll gap of the rolling mill installed on the front side of the finish rolling mill. Then, the speed ratio V ₁ / V ₀ is kept constant.

The cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finishing mill is adjusted by adjusting the roll gap of the rolling mill installed on the front side of the finishing mill, Adjustment is also possible by changing the area.

The wire rod rolling method according to claim 4 is a method in which the rolling speed V _{0 on the} entry side and the rolling speed V ₁ on the exit side of the final finish rolling mill are measured with a laser Doppler speed meter, and the measured rolling speed V ₀ and V ₁ is used to adjust a roll gap of the finish rolling mill or a rolling mill installed on the front side of the finish rolling mill so that the speed ratio V ₁ / V ₀ is constant. To do.

Thus, by measuring the speed of the material to be rolled in the final finish rolling mill, the speed ratio V ₁ / V ₀ can be obtained with high accuracy and the deviation from the preset target speed ratio is corrected. An accurate adjustment index of the material to be rolled on the entry side of the rolling mill can be obtained.

In the present invention, the wire rod is rolled in a hot rolling line equipped with a final finishing mill (sizing mill) on the rear stage side of the finishing mill (block mill), and rolled in the same finish hole mold of the final finishing mill. Then, the speed ratio V ₁ / V ₀ between the speed V _{0 of the} material to be rolled on the entry side and the speed V _{1 of the} material to be rolled on the exit side of the final finish rolling mill is kept constant between the materials to be rolled, Since vibration of the material to be rolled due to fluctuations in the tension between roll stands in the final finish rolling mill is prevented, surface flaws occur due to contact with the guides on the entry side and exit side of the roll, and vibration Troubles such as occurrence of cobbles are avoided, and stable high dimensional precision rolling is realized. Thereby, the product quality and rolling efficiency are improved.

  Embodiments of the present invention will be described below with reference to the accompanying FIGS.

FIG. 1 shows the layout of the finish rolling mill row of the wire rod rolling line shown in FIG. As the finish rolling mill 4, a block mill in which a plurality of (eight in the embodiment) roll stands 8 a to 8 g are alternately arranged with a 90 ° roll axis inclined is installed, and the rear stage side of the finish rolling mill 4, that is, the rolling direction. The final finishing rolling mill 5 is provided with a sizing mill in which a plurality (four in the embodiment) of roll stands 9a to 9d are alternately arranged with a 90 ° roll axis inclined. Intermediate rolling mills 3b that are alternately arranged horizontally and vertically are installed on the upstream side of the finish rolling mill 4, that is, on the upstream side in the rolling direction. The inlet side and outlet side of the final finishing mill 5, a laser Doppler velocimeter 10a, 10b is arranged, to the final finishing mill 5, the entry-side speed V ₀ and the exit-side speed V ₁ of the material to be rolled 11 By actually measuring, the speed ratio F (F = V ₁ / V ₀ ) can be obtained.

As described above, in order to prevent vibration of the material to be rolled in the final finish rolling mill 5, the fluctuation of the area reduction ratio R (R = 1−A ₁ / A ₀ ) in the final finish rolling mill 5 is changed. It is necessary to keep the tension between the roll stands in the final finish rolling mill 5 appropriately. For this purpose, since the cross-sectional area A _{1 of} the material 11 to be rolled on the exit side of the final finish rolling mill 5, that is, the product cross-sectional area A ₁ is constant, the speed ratio F is constant set in advance by a hole rolling schedule. It is necessary to adjust the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finish rolling mill 5 so that the target speed ratio Fa is obtained. The entry side cross sectional area A ₀ of the material to be rolled is adjusted by adjusting the roll gap of at least the last roll stand 8 g of the finish rolling mill 4 or the rolling mill on the front stage side of the finish rolling mill 4 (see FIG. This is possible by adjusting the roll gap of at least the last roll stand 3bf of the intermediate rolling mill 3b) shown in FIG. Further, the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finish rolling mill 5 can be adjusted also by adjusting the roll gap of the first roll stand 8 a of the finish rolling mill 4.

FIG. 2 schematically shows the relationship between the adjustment amount ΔG ₁ of the roll gap of the last roll stand 8 g of the finish rolling mill 4 and the speed ratio fluctuation amount ΔF (ΔF = Δ (V ₁ / V ₀ )). It is. The roll gap adjustment amount ΔG ₁ of the preceding rolling mill of the horizontal axis finishing mill 4 represents the roll gap adjustment amount of the last roll stand 8 g of the finish rolling mill 4, and the vertical axis speed ratio fluctuation amount ΔF is the laser Doppler velocimeter 10a, of the rolled material 11 was measured by 10b, a final finishing mill 5 of the ingress speed V ₀ and the speed determined from the exit-side speed V ₁ ratio _{F (= V 1 / V 0} ), the caliber The difference (F−Fa = V ₁ / V ₀ −V _1S ) from the target speed ratio Fa (Fa = V _1S / V _0S ) determined from the entrance side speed V _0S and the exit side speed V _1S set in advance from the rolling schedule. / V _0S ). By measuring the speed of the material to be rolled and the roll gap adjustment amount in advance, the relationship between ΔG ₁ and the speed ratio fluctuation amount ΔF is obtained in advance, thereby adjusting the roll gap when the speed ratio F varies from the target speed ratio Fa. By obtaining the amount ΔG ₁ and feeding back the speed ratio fluctuation amount ΔF, the speed ratio F can be kept constant. Therefore, by adjusting the roll gap, the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finishing mill 5 is adjusted, and the area reduction rate in the rolling mill 5 can be kept constant. In addition, due to the hole wear of the last roll stand 8g of the finish rolling mill 4, the cross-sectional area of the material to be rolled in the finish rolling mill 4 and, therefore, the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finishing mill 5 is Since this tends to increase with the progress of rolling, the speed V ₀ of the material to be rolled on the entry side tends to decrease. Usually, since the speed V ₁ (finish rolling speed) of the material to be rolled on the delivery side of the final finish rolling mill 5 is constant, the speed ratio F tends to increase, and the speed ratio fluctuation amount ΔF also tends to increase. . For this reason, the speed ratio fluctuation amount ΔF usually takes a positive value, and the roll gap adjustment amount ΔG ₁ indicates the adjustment amount due to the reduction.

FIG. 3 shows the adjustment amount ΔG ₀ of the roll gap of the last roll stand 3bf of the front rolling mill (intermediate rolling mill 3b) of the finish rolling mill 4 and the speed ratio fluctuation amount ΔF (= Δ (V ₁ / V ₀ ). ) Schematically. The roll gap adjustment amount ΔG ₀ of the preceding rolling mill of the horizontal rolling mill 4 is the roll gap adjustment amount of the last roll stand 3bf of the intermediate rolling mill 3b, and the speed ratio fluctuation amount ΔF of the vertical axis is FIG. It is the same as the case of. By determining the relationship between ΔG ₀ and ΔF in advance by actual measurement, the preceding stage when the speed ratio F (= V ₁ / V ₀ ) varies from the target speed ratio Fa (= V _1S / V _0S ). The roll gap adjustment amount ΔG ₀ of the side rolling mill is obtained, and the speed ratio F can be kept constant. Accordingly, by changing the cross-sectional area of the material to be rolled on the entry side of the finish rolling mill 4 by adjusting the roll gap, the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finish rolling mill 5 is adjusted, and the final finish is achieved. The area reduction rate in the rolling mill 5 can be kept constant. Similar to the case of FIG. 2, the speed ratio variation ΔF usually takes a positive value, the roll gap adjustment amount .DELTA.G ₀ indicates the amount of adjustment by the pressure.

The shape of the hole shape of the last roll stand 8g of the finish rolling mill 4 is the upper roll hole type Ku and the lower roll hole shown in FIG. 4 (a) due to wear as the rolling progresses (increase in rolling amount). From the circular shape formed by the mold Kn, a shape close to an ellipse is obtained as shown in FIG. Since the cross-sectional shape of the material being rolled can be grasped to some extent by an on-line dimension measuring device, the area of the shape close to an ellipse as shown in FIG. It is not impossible to adjust the hole roll gap of the last roll stand 8g of the finish rolling mill 4 so that the rate R is constant, but it becomes very complicated and requires time and effort. Therefore, by obtaining the relationship between the cross-sectional area of the rolled material having a shape close to an ellipse that is not constant and the roll gap adjustment amount, adjusting the cross-sectional area A ₀ of the rolled material on the entry side of the final finish rolling mill 5 is Also, it is not practical from the viewpoint of accuracy to keep the area reduction rate R constant. For this reason, it is appropriate from the viewpoint of labor and accuracy to adjust the cross-sectional area A _{0 of the} material to be rolled on the entry side of the final finish rolling mill 5 through the speed ratio F.

In the hot rolling line of the wire shown in FIGS. 1 and 5, rolling from a 155 mm square billet of JIS SCM435 to a wire of 5.5 mm in diameter is performed so that the speed ratio F is kept constant. The case where the adjustment was performed and the case where it was not performed were carried out. Here, the dimension of the rolled material on the exit side of the finish rolling mill 4 is 9 mm in diameter, and the temperature of the rolled material on the entry side of the final finish rolling mill 5 is 900 ° C. The target speed ratio Fa set in advance from the hole rolling schedule from a 155 mm square billet to a wire with a diameter of 5.5 mm is 1.62. From the speeds V ₀ and V _{1 of the} material to be rolled on the entry side and the exit side of the final finish rolling mill 5 measured by the laser Doppler speedometers 10a and 10b, a speed ratio F (= V) is obtained using a data processor (not shown). ₁ / V ₀ ) was calculated and displayed on the monitor. When this speed ratio F varied from the target speed ratio Fa (= 1.62), the roll gap of the rolling mill was manually adjusted. The roll gap adjustment of the rolling mill was performed for each of the last roll stand 8g of the finish rolling mill 4 and the last roll stand 3bf of the preceding rolling mill (intermediate rolling mill 3b) of the finish rolling mill 4. Table 1 shows the rolling situation.

  In Table 1, the circle mark between the stands indicates that the material to be rolled does not vibrate between the roll stands of the final finish rolling mill 5 shown in FIG. The symbol “Δ” indicates that generation of surface flaws was observed within the allowable range, and the symbol “x” indicates that generation of surface flaws outside the allowable range was recognized. In addition, ◯ of dimensional accuracy indicates that the wire diameter (product diameter) of the material to be rolled on the exit side of the finish rolling mill 5 is within a target dimensional tolerance of ± 0.10 mm.

In this way, the speed ratio F, which is the ratio of the speeds V ₀ and V ₁ of the material to be rolled on the entry side and the exit side of the final finish rolling mill, is kept constant, that is, the target set speed ratio Fa is set in advance. Thus, by adjusting the roll gap of the rolling mill and adjusting the cross-sectional area A _{0 of the} material to be rolled on the final finishing rolling mill entry side, fluctuations in the area reduction ratio R in the final finishing rolling mill are suppressed. Further, it is possible to obtain a wire product that prevents vibration of the material to be rolled and generation of surface flaws and satisfies the target dimensional accuracy. The roll gap adjustment of the rolling mill is based on the deviation from the target speed ratio Fa of the actually measured speed ratio F by attaching an automatic reduction device to the rolling mill. it is also possible to carry out automatically by using the relationship between the ratio variation amount _{ΔF (= ΔV 1 / V 0} ) and the roll gap adjustment amount .DELTA.G ₁ or .DELTA.G _0. In the present invention, the product diameter is not limited to 5.5 mm as described above, and the final finish rolling mill (sizing mill) is installed on the rear stage side of the finishing mill (block mill) to roll all product diameters. It is possible to apply to rolling.

It is explanatory drawing which shows the layout of the finish rolling mill row | line of a wire rod rolling line. It is explanatory drawing which shows typically the relationship between the roll gap adjustment amount of the finish rolling mill of embodiment, and the speed ratio fluctuation amount of a to-be-rolled material. It is explanatory drawing which shows typically the relationship between the roll gap adjustment amount of the rolling mill of the front | former stage side of the finish rolling mill of embodiment, and the speed ratio fluctuation amount of a to-be-rolled material. (A), (b) It is explanatory drawing which shows progress of wear of the finishing hole type | mold of a finishing mill. It is explanatory drawing which shows the layout of a wire rod rolling line. It is explanatory drawing which shows an example of the layout of a prior art wire-finishing rolling line. It is explanatory drawing which shows another example of the layout of the wire rod finishing rolling line of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heating furnace 2 ... Rough rolling mill row 3a, 3b ... Intermediate rolling mill row 4 ... Finish rolling mill 5 ... Final finishing rolling mill 6 ... Winding machine 7 ... Water cooling devices 8a to 8g ... Roll stands 9a to 9d of the finishing mill row ... Roll stands 10a and 10b of the final finishing mill ... Laser Doppler speedometer 11 ... Rolled material Ku, Kn ... Roll hole type

Claims (4)

A method of rolling a wire rod in a hot rolling line equipped with a final finish rolling mill on the rear side of the finish rolling mill, wherein the final finish rolling mill is the same finish hole type of the final finish rolling mill. The cross-section reduction of the material to be rolled in the final finish rolling mill is performed by keeping the speed ratio V ₁ / V ₀ between the rolling speed V ₀ on the inlet side and the rolling speed V ₁ on the outlet side constant between the rolled materials. A method of rolling a wire, characterized by suppressing fluctuations in rate. By adjusting the roll gap of the finishing mill, the cross-sectional area of the material to be rolled on the entry side of the final finishing mill is adjusted to keep the speed ratio V ₁ / V ₀ constant. The method for rolling a wire according to claim 1. By adjusting the roll gap of the rolling mill installed on the front side of the finish rolling mill, the sectional area of the material to be rolled on the entry side of the final finishing mill is adjusted, and the speed ratio V ₁ / V ₀ is adjusted. The wire rod rolling method according to claim 1, wherein the wire is kept constant. The final rolling mill is measured with the laser Doppler speedometer for the entrance-side rolling speed V ₀ and the exit-side rolling speed V ₁ , and using the measured rolling speeds V ₀ and V ₁ , the speed ratio V ₁ 4. The roll gap of the finish rolling mill or a rolling mill installed on the front side of the finish rolling mill is adjusted so that / V ₀ is constant. 5. Wire rod rolling method.

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