Specification
Title of invention: Shaped steel rolling method, shaped steel manufacturing line, and shaped steel manufacturing method
Technical field
[0001]
(Cross Reference of Related Applications) The
　present application claims priority based on Japanese Patent Application No. 2018-001784 filed in Japan on January 10, 2018, and the content thereof is incorporated herein.
[0002]
　The present invention relates to a method for rolling a section steel for producing a section steel such as an H section steel, a T section steel, and an I section steel, a section steel manufacturing line, and a section steel manufacturing method.
Background technology
[0003]
　In a rolling process using a continuous rolling mill, material tension between rolling mills is an important factor for determining dimensions such as thickness and width of material. Therefore, in order to maintain a good product size, it is required to appropriately control the tension between rolling mills. In view of such a situation, conventionally, a technique for controlling tension between various rolling mills (also referred to as rolling stands or stands) has been devised.
[0004]
　For example, Patent Document 1 discloses a technique of performing tension control between stands of a continuous rolling mill. Specifically, in Patent Document 1, the relationship between the rolling torque of each rolling stand, the rolling load, the front tension, and the rear tension is linearly related, and the front tension and the rear tension are determined based on the measured values ​​of the rolling torque and the rolling load. The control is performed by estimating and using the estimated value as the target value.
[0005]
　Further, for example, in Patent Document 2, in a continuous rolling mill having two or more rolling mills, the current of the roll drive motor when the material to be rolled bites into the reference rolling mill is stored and the next rolling is performed. A technique for controlling speed by comparing with the current of a roll drive motor when a material to be rolled is bitten into a machine is disclosed.
[0006]
　Further, for example, Patent Document 3 discloses a technique of detecting only the torque fluctuation due to front tension between a plurality of stands of a tandem rolling mill and controlling the tension between the stands. Specifically, in Patent Document 3, the rolling torque of an arbitrary stand is determined based on the rolling torque when the material to be rolled is not bitten into the downstream stand and the rolling torque of the upstream stand at that time. A configuration for obtaining a tensionless torque is disclosed.
Prior art documents
Patent literature
[0007]
Patent Document 1: Japanese Patent Application Laid-Open No. 2008-183594
Patent Document 2: Japanese Patent Application Laid-Open No. 53-34586
Patent Document 3: Japanese Patent Application Laid-Open No. 61-3564
Summary of the invention
Problems to be Solved by the Invention
[0008]
　In a continuous rolling mill including a plurality of rolling mills, tension control between stands (rolling mills) is indispensable, but in the technique described in Patent Document 1, the inter-stand tension is estimated from the linear form, and therefore the linear form is preliminarily used. Therefore, it is necessary to create a linear form through extensive experiments and numerical analysis.
[0009]
　Further, the technique described in Patent Document 2 is based on the premise that the tension with the reference rolling mill can be controlled to be in a tensionless state before the material to be rolled bites into the latter stage stand (next rolling mill). If the distance is short, it may not be applicable.
[0010]
　Further, it is considered that the technique described in Patent Document 3 is based on the premise that the total rolling torque is constant regardless of the tension, and if there is an error in the premise, there is an error in the tension control between stands. It may affect and the tension may not be controlled accurately. Further, the technique of Patent Document 3 is basically created on the premise of rolling a wire rod or a steel plate, and may cause an error when applied to a shaped steel to be rolled by a universal rolling mill. Hereinafter, the reason will be briefly described in [0011] to [0016].
[0011]
　In the said patent document 3, tension control between stands of a tandem rolling mill is performed using the following formulas (1) and (2).
[

　Equation 1] The above equation is considered to be based on the premise that the total rolling torque at the total stand is constant regardless of the tension. As an example, consider a case where the total number of stands is three (first to third stands). Based on the above equations (1) and (2), the rolling torque G at each stand is derived from the relationship shown in the following equations (A1) and (A2).

[

　Equation 2] These equations (A1) and (A2) are related on the premise that the total work load of all stands is constant regardless of the tension state. For example, rolling of shaped steel such as H-shaped steel. Then, the shape of the rolled material in the cross section changes due to the tension between the stands, and the total work amount changes. Specifically, in the universal rolling of shaped steel, there is a reduction due to the side surface of the horizontal roll and the peripheral surface of the vertical roll, and the frictional force that varies depending on the position acts between the horizontal surface of the horizontal roll and the peripheral surface of the vertical roll. Therefore, when the dimension of the rolled material changes due to the tension between the stands, the total work may change. Therefore, it is appropriate to express the relationship between the tension and the rolling torque G by the following equations (B1) to (B3) including the influence coefficient. In the following, as the tension T between the stands, the tension between the first and second stands is T12, and the tension between the second and third stands is T23, and A12, A23, B12, and B23 are It is the influence coefficient between each stand.

[Number 3]

　In the above formulas (B1) to (B3), if A12=B12 and A23=B23, the relations shown in the above formulas (A1) and (A2) are established. May not be constant, and the relationship of A12=B12 and A23=B23 may not hold.
[0012]
　When comparing the above formulas (A1) with the formulas (B1) and (B2), the formulas (B1) and (B2) are used before the material to be rolled is caught in the third stand (that is, T23 = 0). When transformed, the following equation (B4) is derived.

[

　Equation 4] Below, equations (A1) and (B4), which are equations for deriving the second stand rolling torque G20 when the second stand is not tensioned, are described together, and the equation (B4) is further modified. Formula (B4)′ is used for comparison.

[

　Equation 5] From the comparison between the formula (A1) and the formula (B4) or the formula (A1) and the formula (B4)′, the tension control in the rolling of the shaped steel is performed by the formula (1), ( It can be seen that the error of (B12/A12-1)(G1*-G10)=-(A12-B12)T12 is included in the case of using 2).
[0013]
　The above-described error increases as the inter-stand tension T12 increases. In general rolling in a rolling mill train, a tensioned state (that is, T12>0) is set in order to prevent a threading failure at the time of biting. Therefore, in the case of A12>B12, there is no tension. The second stand rolling torque G20 is overestimated, and when A12 B12. That is, when the tension control based on Patent Document 3 is performed under such a rolling condition of the shaped steel, the second stand rolling torque G20 in the non-tensioned state is calculated too small.
[0016]
　Also from the results of such numerical analysis, in the rolling of shaped steel, the shape of the material to be rolled changes due to the tension between the stands, and there is a reduction due to the horizontal roll side surface and the vertical roll peripheral surface. It is estimated that the total work amount fluctuates because different frictional forces act depending on the position between and the rolled material.
[0017]
　By the way, in continuous rolling equipment where energy saving and cost saving are required, the distance between the stands of a plurality of stands may be shortened in order to make the equipment compact. When performing tandem rolling, if the distance between the stands is shortened, a condition in which the material to be rolled is caught in the downstream stand occurs before the upstream rolling stands are controlled to be in a tension-free state. Such conventional technology may not be applicable. For example, under the condition that the recovery from the decrease in the number of revolutions immediately after biting of each rolling stand (so-called impact drop) is about 0.5 seconds and the biting speed of each rolling stand is 3 m/s, If the distance between the stands is 1.5 m or less, the tension control may not be in time before the rolled material is caught in the downstream stand.
[0018]
　Therefore, in view of the above circumstances, an object of the present invention is a condition in which the distance between stands is short when rolling a shaped steel using a continuous rolling mill consisting of three or more rolling mills in a tandem state. However, with a simple control system that does not use table values ​​for each rolling condition, the tension between stands can be controlled with high accuracy to stabilize threading and improve product dimensional accuracy. It is to provide a method, a section steel manufacturing line, and a section steel manufacturing method.
Means for solving the problem
[0019]
　In order to achieve the above-mentioned object, according to the present invention, when performing tandem rolling in a rolling mill train constituted by at least three rolling mills of n rolling mills, one or more rolling mills are used to form a horizontal roll side surface. A method for rolling a shaped steel for performing rolling reduction between a vertical roll peripheral surface, which is for each rolling mill Ri of the rolling mill train, after a material to be rolled is bitten into the rolling mill Ri, and Before the material to be rolled bites into the rolling mill Ri+1 located downstream of the rolling mill Ri, the rotation speed of the rolling mill Ri is fixed, and the rolling torque Gi of the rolling mill Ri at that time is stored as Gi*, After the material to be rolled is caught in the rolling mill Rn at the most downstream of the rolling mill row, the rolling torque Gn-1 of the rolling mill Rn-1 located upstream of the rolling mill Rn is rolled into the rolling mill Rn. A first control step of controlling the rotation speed of the rolling mill Rn so that it becomes equal to Gn-1* stored as the rolling torque of the rolling mill Rn-1 before the material bites, and the first control. The rolling torque Gn** of the rolling mill Rn after the process is stored, and the rolling torque Gn-2 of the rolling mill Rn-2 positioned upstream of the rolling mill Rn-1 is stored in the rolling mill Rn-1. The number of revolutions of the rolling mill Rn-1 is controlled so as to be equal to Gn-2* stored as the rolling torque of the rolling mill Rn-2 before the rolled material bites, and the rolling mill Rn is controlled. A second control step of controlling the rotation speed of the rolling mill Rn so that the rolling torque Gn of the rolling mill becomes equal to the stored rolling torque Gn**, and the second control step is applied to all rolling mills Ri. So that the rolling torque G1 of the most upstream rolling mill R1 becomes equal to G1* stored as the rolling torque of the rolling mill R1 before being bitten into the rolling mill R2 located downstream of the rolling mill R1. A method for rolling shaped steel is provided, characterized in that the number of revolutions of each rolling mill Ri of the rolling mill train is controlled. However, i is an arbitrary integer of 1 to n, and n is an integer of 3 or more.
[0020]
　Control using the torque arm coefficient (G / P), which is the value obtained by dividing the rolling torque of each rolling mill by the rolling load of the rolling mill, instead of the value of the rolling torque of each rolling mill in the rolling mill row. You may go.
[0021]
　After controlling the rotation speeds of all the rolling mills Ri of the rolling mill train, rolling may be performed with the rotation speed ratio of each rolling mill Ri fixed.
[0022]
　The rolling speed of the rolling mill Rn at the most downstream side of the rolling mill train may be increased to a desired speed while the rotation speed ratio of each rolling mill Ri is fixed.
[0023]
　Further, according to the present invention from another viewpoint, a rolling mill row composed of at least three or more n rolling mills and at least one or more rolling mills or rolling mill rows are arranged in tandem in this order. In the manufacturing line of a shaped steel in which rolling is performed between the horizontal roll side surface and the vertical roll peripheral surface by one or more rolling mills, in the rolling line upstream of the rolling mill, After the tension-free control of the material to be rolled is completed and the tension-free control is completed, the rolling mill or rolling mill row at the upstream side has a sufficient distance for the rolled material to be caught in the rolling mill or rolling mill row at the downstream side. A downstream rolling mill or a row of rolling mills is arranged, and the upstream rolling mill row and the downstream rolling mill or a row of rolling mills independently carry out the above-described rolling method for shaped steel. The production line of shaped steel is provided.
[0024]
　Further, according to the present invention, there is provided a method for manufacturing a shaped steel which is manufactured by performing a reduction between a side surface of a horizontal roll and a peripheral surface of a vertical roll, which is composed of at least three or more n rolling mills. In the rolling mill train, for each rolling mill Ri, after the material to be rolled bites into the rolling mill Ri, and before the material to be rolled bites into the rolling mill Ri+1 located downstream of the rolling mill Ri. , The rolling speed of the rolling mill Ri is fixed, and the rolling torque Gi of the rolling mill Ri at that time is stored as Gi*. The rolling torque Gn-1 of the rolling mill Rn-1 located upstream of the rolling mill Rn is stored as the rolling torque of the rolling mill Rn-1 before the material to be rolled bites into the rolling mill Rn. The first control step of controlling the rotation speed of the rolling mill Rn and the rolling torque Gn** of the rolling mill Rn after the first control step are stored so as to be equal to 1*, and then the rolling is performed. The rolling torque Gn-2 of the rolling mill Rn-2 located upstream of the rolling mill Rn-1 is stored as the rolling torque of the rolling mill Rn-2 before the material to be rolled bites into the rolling mill Rn-1. The rolling speed of the rolling mill Rn-1 is controlled to be equal to Gn-2*, and the rolling torque Gn of the rolling mill Rn is equal to the stored rolling torque Gn**. A second control step for controlling the number of rotations of Rn is provided, the second control step is applied to all the rolling mills Ri, and the rolling torque G1 of the most upstream rolling mill R1 is downstream of the rolling mill R1. Section steel is manufactured by controlling the number of revolutions of each rolling mill Ri of the rolling mill row so as to be equal to G1* stored as the rolling torque of the rolling mill R1 before being bitten into the rolling mill R2 located at A method for producing shaped steel is provided, which is characterized by rolling out.
Effect of the invention
[0025]
　According to the present invention, when rolling a section steel using a continuous rolling mill consisting of three or more rolling mills in a tandem state, even if the distance between stands is short, With a simple control system that does not use table values ​​and the like, it is possible to control the tension between stands with high accuracy, stabilize the threading, and improve the product dimensional accuracy.
Brief description of the drawings
[0026]
FIG. 1 is a schematic explanatory view of an H-section steel production line.
FIG. 2 is a schematic explanatory view of a universal rolling mill and an edger rolling mill.
FIG. 3 is a schematic plan view of a rolling mill train including three rolling mills R1-R2-R3.
[Fig. 4] Fig. 4 is a schematic explanatory view of tension control when the distance between stands is long.
FIG. 5 is a schematic explanatory diagram when conventional tension control is applied when the distance between stands is extremely short.
FIG. 6 is a schematic explanatory view when the tension control according to the present invention is applied when the distance between stands is extremely short.
FIG. 7 is a schematic explanatory view showing a combination of a rolling mill train including adjacent rolling mills R1 to R3 and a rolling mill at a downstream position sufficiently distant from the rolling mill train.
[Fig. 8] A row of rolling mills composed of rolling mills R1 to R3 that are close to each other and a second row of rolling mills consisting of rolling mills R4 to R6 that are close to each other at a downstream position sufficiently distant from the row of rolling mills. It is a schematic explanatory drawing which shows a combination.
FIG. 9 is a schematic explanatory diagram of universal intermediate rolling of H-section steel.
[Fig. 10] Fig. 10 is a graph showing the amount of torque change of each stand when the tension between the stands changes by numerical analysis.
MODE FOR CARRYING OUT THE INVENTION
[0027]
　Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification and the drawings, constituent elements having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted. In addition, in this specification, as a rolling mill constituting the continuous rolling mill, a universal rolling mill and an edger rolling mill used in the case of manufacturing an H-shaped steel product are illustrated as examples, but the scope of application of the present invention is It is not limited to this. Further, the "universal rolling mill" in the present specification refers to a rolling mill that performs rolling accompanied by a large stretch using horizontal rolls and vertical rolls at the time of shape steel rolling, and "edger rolling" together with the universal rolling mill. It refers to a rolling mill that is used and performs rolling with an extremely light reduction, and in the present specification, the rolling mill may be referred to as a "rolling stand" or simply "stand".
[0028]
　(Outline of Production Line and Conventional Problems)
　FIG. 1 is an explanatory diagram of a production line L in which the method for rolling a shaped steel according to the present embodiment is carried out. As shown in FIG. 1, in the production line L, a heating furnace 2, rough rolling mills 4, two intermediate universal rolling mills 5 and 6, and a finish universal rolling mill 8 are arranged in this order from the upstream side. An edger rolling mill 9 is provided between the two intermediate universal rolling mills 5 and 6. In the following, for the sake of explanation, the steel material in the production line L may be generically referred to as "rolled material S", and the shape thereof may be illustrated using broken lines, diagonal lines, etc. in each drawing as appropriate.
[0029]
　As shown in FIG. 1, in the production line L, the material S to be rolled, such as the slab 11 extracted from the heating furnace 2, is roughly rolled in the rough rolling machine 4. Next, intermediate universal rolling is performed in the intermediate universal rolling mills 5 and 6. Further, in a state in which the intermediate universal rolling and the reverse rolling are possible, the edger rolling machine 9 rolls down the end portion (flange-corresponding portion 12) of the material to be rolled. Generally, the rolls of the rough rolling mill 4 (in some cases, a plurality of bases may be installed) have a total of about 4 to 6 hole shapes engraved, and through these, reverse rolling of multiple passes. A dogbone-shaped H-shaped rough material 13 is formed by using a rolling mill train including a first intermediate universal rolling mill 5-edger rolling mill 9-second intermediate universal rolling mill 6. Then, a plurality of passes of reduction are applied to form the intermediate material 14. Then, the intermediate material 14 is finish-rolled by the finish universal rolling mill 8 into a product shape, and the H-section steel product 16 is manufactured.
[0030]
　In the production line L shown in FIG. 1, a rolling mill consisting of a first intermediate universal rolling mill 5-edger rolling mill 9-2nd intermediate universal rolling mill 6 is used for the H-shaped rough material 13 to reduce a plurality of passes. 2A, when the intermediate material 14 is molded, the flange tip end is unpressed (see the broken line portion in the figure) in each universal rolling machine as shown in FIG. 2(a). As shown, the edger rolling machine performs rolling such that the unrolled portion is shaped and rolled.
[0031]
　As an example of a continuous rolling mill line that rolls a material to be rolled in a tandem state, the configuration of the first intermediate universal rolling mill 5-edger rolling mill 9-2 second intermediate universal rolling mill 6 as described above can be mentioned. When a shaped steel is rolled as the material to be rolled S in a row of rolling mills in which a plurality of rolling stands are continuously arranged, the rigidity of the material to be rolled is large, so that the looper is used when rolling a steel strip or the like. It is difficult to control the tension between rolling stands using the (tension control device). Also, in the rolling of shaped steel, in order to prevent passing defects such as rolling of rolled materials between rolling stands and to secure stable passing, the tension between stands should be pulled slightly when biting. It was common to set a different rotation speed. That is, in order to maintain good product dimensions in the rolling of shaped steel, it is required to appropriately control the tension between the stands after the material to be rolled is bitten.
[0032]
　In addition, in the continuous rolling mill line, the distance between the stands of a plurality of stands may be shortened in order to save energy, save costs, and make the equipment compact. However, when tandem rolling of shaped steel is performed, if the distance between the stands is shortened, there is a risk that the material to be rolled may get caught in the downstream stand before the distance between the upstream rolling stands is controlled to be in a non-tension state. However, there is a possibility that stable control such as pulling tension between stands as in the past cannot be performed stably.
　In view of such circumstances, in a continuous rolling mill train that performs tandem rolling of shaped steel, even if the distance between stands is short, the tension between stands can be controlled with high accuracy to stabilize the threading and product dimensions. There is a demand for technology that can improve accuracy.
[0033]
　(Application Example of Tension Control Method) In the
　production line L shown in FIG. 1, the configuration of the first intermediate universal rolling mill 5-edger rolling mill 9-second intermediate universal rolling mill 6 (see FIG. 2) is used as the continuous rolling mill train. However, the tension control method according to the present invention can be applied to any rolling mill as long as it has a configuration in which a plurality of rolling mills (stands) are continuously arranged in equipment for performing tandem rolling of shaped steel. Applicable. Therefore, in the following, a case where the conventional tension control method and the tension control method according to the present invention are applied to a row of rolling mills in which three stands of R1 to R3 are continuously arranged will be described as an example. This configuration is an example, and the tension control method according to the present invention can be applied to a rolling mill train of shaped steel in which at least three rolling mills are in a tandem rolling state.
[0034]
　FIG. 3 is a schematic plan view of a rolling mill train 30 including three rolling mills R1-R2-R3. In the rolling mill train 30, for example, reverse rolling is performed as indicated by a dashed arrow in the drawing. . The distance between the stands of the three rolling mills (rolling stands) R1, R2, and R3 is shorter than the longitudinal length of the material S to be rolled, and the material S to be rolled is rolled in a so-called tandem rolling state. Be seen. Further, when the tension control method according to the present invention is applied, the distance between these stands is sufficiently shorter than the rolling speed of the material S to be rolled, that is, before it bites into the downstream stand, it is individual. The superiority of the present invention over the prior art is exhibited when the tension between the stands cannot be made non-tensioned. However, the present invention can also be applied to a long stand-to-stand distance to which, for example, Patent Document 2 (Japanese Patent Publication No. 53-34586) can be applied.
[0035]
　(Conventional Tension Control and Problems Thereof)
　First, in the rolling mill train 30 including three rolling mills R1-R2-R3, the tension control when the stand-to-stand distance is sufficiently long will be described. Here, the configuration of “the distance between the stands is sufficiently long” indicates that there is a sufficient distance between the stands for the tension-free control of the material S to be rolled and for stabilizing.
[0036]
　FIG. 4 is a schematic explanatory diagram relating to tension control when the distance between stands is long, and is a schematic diagram showing changes in rolling torque (solid line) and changes in rotational speed (dotted line) of the rolling mills R1 to R3. Below, each rolling torque of R1 to R3 is defined as G1 to G3 as a value that changes with time, and each rolling torque value at a specific time point is described as an individual value such as “G1*”. Note that FIG. 4 also shows a schematic diagram of the position of the material S to be rolled in situations A and B in the schematic diagram (FIG. 4 ). Tension control when the distance between the stands is long will be described with reference to FIG.
[0037]
1) In the previous stage of the situation A shown in FIG. 4, the rolling torque G1* of R1 is stored immediately before the material S to be rolled bites into R2. Then, in the situation A, after the material S to be rolled is caught in R2, the rotation speed of R1 is controlled so that G1=G1*, and a tensionless state (static state) is established between R1 and R2. The rolling torque G2* of R2 in the state is stored.
2) In the situation B shown in FIG. 4, after the material S to be rolled is caught in R3, the rotation speed of R2 is controlled so that the rolling torque G2 of R2 is G2=G2*. As a result, both R1-R2 and R2-R3 are controlled to be in a tensionless state.
[0038]
　Next, a case will be described in which the conventional tension control is applied to a rolling mill train 30 including three rolling mills R1-R2-R3 with a configuration in which the distance between stands is extremely short. Here, "a configuration in which the distance between the stands is extremely short" refers to a configuration in which the material to be rolled S is caught in the downstream stands before the upstream rolling stands are controlled to be in a tension-free state.
[0039]
　FIG. 5 is a schematic explanatory diagram when the conventional tension control is applied when the distance between the stands is extremely short, and shows changes in rolling torque (solid line) and changes in rotational speed (dashed line) of the rolling mills R1 to R3. It is a schematic diagram. In addition, also in FIG. 5, the schematic diagram about the position of the rolled material S in the situations A and B in the schematic diagram (FIG. 5) is also shown. A case where the conventional tension control is applied in a configuration in which the distance between the stands is extremely short will be described with reference to FIG.
[0040]
1) In the previous stage of the situation A shown in FIG. 5, the rolling torque G1* of R1 is stored immediately before the material S to be rolled bites into R2. Then, in the situation A, after the rolled material S bites into R2, the rotation speed control of R1 is performed so that G1=G1*, but the rolled material S bites into R3 before the control is completed. Get caught. Even if the rolling torque G2 * of R2 is stored in this state, the stored G2 * is a value in a state where the rear tension is applied.
2) In the situation B shown in FIG. 5, even if control is performed such that G2=G2* and G1=G1*, as described above, the stored G2* is in the state in which the backward tension is applied. Since it is a value, a tension-free state is not created between R2 and R3, and proper tension control cannot be realized.
[0041]
　As described above with reference to FIGS. 4 and 5, in the rolling mill train 30 including the three rolling mills R1-R2-R3, when the distance between the stands is sufficiently long, the conventional tension control technique is used. Although suitable tension control is possible by applying it (see FIG. 4), there is a problem that the conventional tension control technology cannot realize suitable tension control (see FIG. 5) when the distance between stands is extremely short. Be done.
[0042]
　In view of the above problems, the present inventors rotate in a state where the front tension is 0 (before the material S to be rolled is caught in the downstream rolling mill) when tension control is performed in a rolling mill train including a plurality of rolling mills. A fixed number was set, and after the material S to be rolled bites into all the target rolling mills, a tension control method for making the inter-stand tension zero by sequentially going back and a rolling method using the same were devised. Hereinafter, the rolling method according to the present invention will be described.
[0043]
　(Rolling Method/Tension Control According to the Present Invention) In
　the rolling mill train 30 including three rolling mills R1-R2-R3, the tension control technique according to the present invention is applied to the configuration in which the distance between stands is extremely short. The case will be described. The tension control technology according to the present invention can be applied to a case where tandem rolling is carried out in a rolling mill train including n rolling mills (n = any integer greater than or equal to 3). For simplification, a rolling mill train 30 including three rolling mills R1-R2-R3 will be described here.
[0044]
　FIG. 6 is a schematic explanatory view when the tension control according to the present invention is applied when the distance between the stands is extremely short, and changes in rolling torque (solid line) and rotation speed (dashed line) of the rolling mills R1 to R3 are shown. It is a schematic diagram which shows. Note that FIG. 6 also shows a schematic diagram of the position of the material S to be rolled in the situations A to C in the schematic diagram (FIG. 6). A case where the tension control according to the present invention is applied in a configuration in which the distance between stands is extremely short will be described with reference to FIG.
[0045]
1) In the stage prior to the situation A shown in FIG. 6, the rolling torque G1 * of R1 is stored immediately before the material S to be rolled bites into R2.
2) Situation A shown in FIG. 6, that is, immediately before the material S to be rolled bites into R3, the rolling torque G2* of R2 is stored, and the rotational speed of R1 is fixed at this stage.
3) Situation B shown in FIG. 6, that is, after the material S to be rolled bites into R3, the rolling torque G2 of R2 becomes equal to the stored G2* (G2=G2*), and rotation of R3 is performed. Control the number. After the control stabilization, there is no tension between R2 and R3. The rolling torque G3 ** of R3 in this state is stored.
4) Between the situations B and C shown in FIG. 6, the rotational speed of R2 is controlled so that G1=G1* (that is, tension between R1 and R2 is zero). By controlling the rotational speed of R2 (changing the rotational speed), tension or compression force acts between R2 and R3. At that time, the rotational speed of R3 is maintained so that G3=G3** is maintained. Control.
5) In the situation C shown in FIG. 6, the rolling torque G2 ** of R2 at the time when the tension between R1-R2 and R2-R3 is settled is stored.
6) G1*, G2**, and G3** stored in the above process are rolling torques when the front/rear tension is 0, so G1=G1*, G2=G2**, and G3= By controlling the number of revolutions of each rolling mill so as to be G3**, the tensionless state can be maintained over the entire length of the rolling mill train.
[0046]
　By adopting the tension control method described in 1) to 6) with reference to FIG. 6 in tandem rolling in the rolling mill row 30, between the rolling stands (between R1-R2 and R2-R3). The tension control is performed with high accuracy, and it becomes possible to carry out rolling while maintaining the non-tension state. This improves the threadability of the material to be rolled between the rolling stands, and prevents deterioration of dimensional accuracy, slippage, and swelling due to compressive force.
[0047]
　Further, in the present embodiment, the measurable rolling torque is stored without using the table value or the like for each rolling condition, and the tension over the entire length of the rolling mill train 30 composed of R1-R2-R3 is stored by a simple control system. Control can be performed with high accuracy.
[0048]
　(Application to Rolling Mill Sequence Composed of Arbitrary Multiple Rollers) In
　the description with reference to FIG. 6, the tension control according to the present invention is applied to the rolling mill train 30 including the three rolling mills R1-R2-R3. Although the case has been described, the scope of application of the present invention is not limited to this. That is, the technology of the present invention can be applied to a rolling mill train including an arbitrary plurality of rolling mills of three or more. Hereinafter, a tension control method in the case of performing tandem rolling in a rolling mill train consisting of three or more arbitrary n rolling mills will be described. In the following, for the sake of explanation, each rolling mill constituting a rolling mill train consisting of n rolling mills is referred to as R1, R2,... Rn, and the i-th rolling mill among them is Ri, The rolling torque is defined as Gi. That is, i is an arbitrary integer of 1 to n, and n is an integer of 3 or more.
[0049]
1) In rolling mills Ri other than the most downstream rolling mill Rn, after the material to be rolled bites into Ri, the rolling torque Gi* of Ri immediately before biting into the downstream rolling mill Ri+1 is stored, and Ri is stored at this stage. The number of rotations of is fixed.
2) After the material to be rolled bites into the most downstream rolling mill Rn, the rolling torque Gn-1 of the most downstream rolling mill Rn-1 immediately before becomes the memorized rolling torque Gn-1* before Rn biting. In this way, the rotation speed of the most downstream rolling mill Rn is controlled (first control step). By this control, the tension state of Rn-1 becomes equal to the state immediately before the material to be rolled is engaged in the most downstream rolling mill Rn (forward tension = 0).
3) The rolling torque Gn** of the rolling mill Rn after the tension control settling in the first control step is stored.
4) The rolling torque Gn-2 of the rolling mill Rn-2 located upstream of the rolling mill Rn-1 is stored as the rolling torque of the rolling mill Rn-2 before the material to be rolled bites into the rolling mill Rn-1. The rolling speed of the rolling mill Rn-1 is controlled so as to be equal to Gn-2*, and the rolling torque Gn** of the rolling mill Rn is maintained at the rolling torque Gn** stored in the above 3). Then, the rotation speed of the rolling mill Rn is controlled (second control step). Here, the rolling torque Gn-1** of the rolling mill Rn-1 is stored after the tension control is settled.
5) After that, in the same manner, the second control step is performed for each rolling mill so as to sequentially trace upstream. That is, for each rolling mill Rn-1, Rn-2,... R1, the rolling torque Gi of the rolling mill immediately before the rolling mill becomes the rolling torque Gi* stored before being bitten into the rolling mill. To control the rotation speed of each rolling mill and keep the rolling torques Gi+1 to Gn of the rolling mills Ri+1 to Rn downstream of the rolling mill to maintain the rolling torques Gi+1** to Gn** stored after tension settling. , Ri+1 to Rn, the tensionless state can be similarly achieved between the rolling mills after the control.
6) Finally, the rolling torque G1 of the most upstream rolling mill R1 is equal to the rolling torque G1 * stored as the rolling torque of the rolling mill R1 before engaging with the rolling mill R2 located downstream of the rolling mill R1. The rotation speed of each rolling mill Ri of the rolling mill train is controlled so that
[0050]
　The first control step in the above-described tension control method is a step of controlling the rotation speed of the rolling mill Rn so that Gn-1=Gn-1*, and is an Rn independent control step. Further, in the second control step, the rotation speed of the rolling mill Ri is controlled so that Gi = Gi *, and Gk = Gk ** (k =) with respect to the rolling mill Rk downstream of the rolling mill Ri. This is an interlocking control step of controlling the rotation speed so as to maintain (i+1 to n). By sequentially applying the second control step from the rolling mill Rn-1 toward the upstream side, the tension state between all the rolling mills can be controlled.
[0051]
　As described above, after the material to be rolled is bitten into the rolling mill Rn at the most downstream side, the tension control is performed so as to sequentially trace back toward the upstream side, and finally the rolling mill Rn at the most upstream side is controlled to perform rolling. It is possible to perform tension control so that the rolling mills are in a tension-free state for the entire train.
[0052]
　Although an example of the embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the ideas described in the claims, and these also naturally belong to the technical scope of the present invention. Understood.
[0053]
　The rolling method according to the present invention described in the above embodiment does not particularly mention the temperature change of the material S to be rolled during rolling. However, when the dimension of the material S to be rolled is long in the longitudinal direction, the temperature of the material S to be rolled changes with time when performing tandem rolling in a rolling mill train including a plurality of rolling mills such as R1-R2-R3. And the rolling torque of each rolling mill may fluctuate as the temperature changes. If the above tension control method is applied without considering the fluctuation of the rolling torque due to the temperature change, an error may occur due to the fluctuation.
[0054]
　In view of such circumstances, when applying the tension control technique described in the above-mentioned embodiment, it is a value obtained by dividing the rolling torque (G) by the load (P) instead of the value of the rolling torque (G). A torque arm coefficient (G/P) may be used. By performing the tension control method according to the present invention by using the torque arm coefficient (G/P) instead of the rolling torque, the influence of the rolling torque change due to the temperature change of the material to be rolled S is eliminated, and the inter-stand tension is increased. Can be controlled.
[0055]
　Further, when the tension-free state (static state) in the rolling mill train is realized by the rolling method described in the above embodiment, the mill rigidity of the rolling mill train is sufficiently large with respect to temperature change, When the dimensional change of the entire length of the row is small, the rotation speed ratio of each rolling mill in the statically set state may be fixed. For example, when it is desired to increase the rolling speed after the stationary state, it is necessary to increase the rolling speed of the entire rolling mill train. At that time, the tension-free state (static state) can be maintained by increasing the speed while keeping the fixed rotation speed ratio as it is. At that time, the most downstream rolling mill downstream of the rolling is set to a desired speed, and the rolling speeds of the other rolling mills are determined so that the above rotation speed ratio remains as it is in accordance with the rolling speed of the most downstream rolling mill. Just do it.
[0056]
　(Modification of the Invention)
　FIG. 7 shows a combination of a rolling mill train 30 including rolling mills (stands) R1 to R3 that are close to each other, and a rolling mill F1 that is located at a downstream position sufficiently distant from the rolling mill train 30. It is a schematic explanatory drawing shown. In the configuration as shown in FIG. 7, the tension control method described in the above embodiment is applied to the rolling mill train composed of R1 to R3, the tensions of R1 to R3 are settled, and then the material to be rolled is rolled. After S is bitten into F1, the rotational speed of F1 may be controlled so that the value of the rolling torque G3 of R3 is G3=G3** (rolling torque of R3 after settling). As a result, the tension-free state can be maintained between R3 and F1.
[0057]
　Further, FIG. 8 shows a second rolling mill including a rolling mill train 30 including rolling mills R1 to R3 that are close to each other, and rolling mills F1 to F3 that are close to each other and are located at a sufficiently downstream position from the rolling mill train 30. It is a schematic explanatory drawing which shows the combination with the machine train 50. In the configuration as shown in FIG. 8, in the rolling mill train 30 composed of R1 to R3, the tension control method described in the above-described embodiment is applied, the tensions of R1 to R3 are allowed to settle, and F1 is rolled. The rotation speeds of R1 to R3 are fixed before the material S is caught. In this way, with the rotational speeds of R1 to R3 fixed, the tension control method described in the above embodiment is applied to the second rolling mill train 50 in the same manner to settle the tension states of F1 to F3. .. Then, tension control between the rolling mill train 30 and the second rolling mill train 50 may be controlled by an arbitrary control method, for example, G3=G3** (rolling torque of R3 after settling). The rotation speed of F1 may be controlled so as to be.
Example
[0058]
　Tandem rolling with 4 rolling mill trains (R1 to R4 from upstream) with a distance of 2.0 m between rolling mills and a total rolling reduction of 40% and a rolling speed of 4.0 m/s on the rolling mill exit side. The case where the tension between the stands was controlled by the present invention (Example) and the case where the tension between the stands was controlled by using the prior art (Comparative Examples 1 and 2) were compared.
　In Comparative Example 1, the technique disclosed in Patent Document 2 (Japanese Patent Publication No. 53-34586) is used as a conventional technique, the rolling torque is stored 0.1 second before biting into the downstream stand, and 0 after biting into the downstream stand. After 5 seconds, the rotation speed was controlled so that the rolling torque became the value stored before the downstream stand biting. Here, the timing of storing the rolling torque was set to 0.1 second before the biting of the downstream stand, because the rolling speed was estimated from the distance between the stands and the roll speed, and the time to bite the rolled material into the downstream stand was determined. This is to prevent the storage timing of the rolling torque from being after the biting of the downstream stand by adding the estimation error to the estimation. Further, the control start is set to 0.5 seconds after the downstream stand is bitten, which is the time required to avoid a transient state such as recovery from a decrease in the rotation speed (impact drop) due to the biting.
　Further, in Comparative Example 2, the technique disclosed in Patent Document 3 (Japanese Patent Publication No. 61-3564) is used as a conventional technique, and the non-tension torque Gj0 of the stand is calculated 0.1 seconds before the downstream stand is engaged. After the material to be rolled was caught in all the stands, control was performed so that the tension between the stands was set to 0. Here, the calculation timing of the non-tension torque Gj0 is set to 0.1 second before the downstream stand is bitten, because the rolling speed is estimated from the stand-to-stand distance and the roll speed, and the time when the material to be rolled is bitten into the downstream stand. This is to prevent the memory timing of the rolling torque from being after the downstream stand is bitten by adding an estimation error in order to estimate.
[0059]
　When the present invention was applied (Example), rolling without rolling on the material to be rolled was possible. On the other hand, in Comparative Example 1, the time for carrying out the tension control of R1-R2 is only 0.07 seconds until the rolling torque of R2 is stored, and the rolling torque G1 of R1 is settled to the value stored before the biting of R2. could not. Further, with respect to R3, the timing of memorizing the rolling torque overlapped with the transient state after biting, and the rolling torque was bitten into R4 without controlling the tension between R2 and R3. As a result, a significant compressive force was generated between R3 and R4, and the material to be rolled slid between the stands.
　In Comparative Example 2, although rolling in the steady portion did not occur and rolling was possible, the rolling torque of R3 suddenly decreased immediately after R2 kicking, and as a result, a control command to accelerate R3 was issued. Rolling occurred in the rolled material between R4.
Industrial availability
[0060]
　INDUSTRIAL APPLICABILITY The present invention can be applied to, for example, a rolling method of a shaped steel for producing a shaped steel such as an H-shaped steel, a T-shaped steel, and an I-shaped steel, a manufacturing line of the shaped steel, and a manufacturing method of the shaped steel.
Explanation of symbols
[0061]
　2... Heating furnace
　4... Coarse rolling mill
　5... (First) intermediate universal rolling mill (U1)
　6... (Second) intermediate universal rolling mill (U2)
　8... Finishing universal rolling mill
　9... Edger rolling mill (E)
　30 Rolling mill row
　50... Second rolling mill row
　S... Rolled material
　L... Manufacturing line
The scope of the claims
[Claim 1]
In performing tandem rolling in a rolling mill train composed of at least three rolling mills, shaped steel that performs rolling between a horizontal roll side surface and a vertical roll circumferential surface by one or more rolling mills. In the rolling method of the
above, for each rolling mill Ri in the rolling mill row, the rolling mill Ri + 1 located after the material to be rolled is bitten into the rolling mill Ri and downstream of the rolling mill Ri + 1 is covered. Before the rolled material bites, the number of rotations of the rolling mill Ri is fixed, the rolling torque Gi of the rolling mill Ri at that time is stored as Gi *, and the
rolling mill Rn at the most downstream of the rolling mill row is rolled. After the material is bitten, the rolling torque Gn-1 of the rolling mill Rn-1 located upstream of the rolling mill Rn is the rolling torque of the rolling mill Rn-1 before the material to be rolled bites into the rolling mill Rn. The first control step that controls the number of rotations of the rolling mill Rn so as to be equal to Gn-1 * stored as the torque, and
the rolling torque Gn ** of the rolling mill Rn after the first control step.
Then, the rolling torque Gn-2 of the rolling mill Rn-2 located upstream of the rolling mill Rn-1 is stored in the rolling mill Rn-2 before the material to be rolled bites into the rolling mill Rn-1. The rotation speed of the rolling mill Rn-1 is controlled so as to be equal to Gn-2* stored as the rolling torque of the rolling mill and the rolling torque Gn of the rolling mill Rn is stored as the stored rolling torque Gn**. A second control step of controlling the number of revolutions of the rolling mill Rn to be equal
to each other, and applying the second control step to all of the rolling mills Ri so that the rolling torque G1 of the most upstream rolling mill R1 is , Controlling the number of revolutions of each rolling mill Ri of the rolling mill train so as to be equal to G1* stored as the rolling torque of the rolling mill R1 before being engaged with the rolling mill R2 located downstream of the rolling mill R1. A method for rolling shaped steel, comprising:
　However, i is an arbitrary integer of 1 to n, and n is an integer of 3 or more.
[Claim 2]
Control using a torque arm coefficient (G/P) that is a value obtained by dividing the rolling torque of each rolling mill by the rolling load of the rolling mill instead of the value of the rolling torque of each rolling mill in the rolling mill train. The method of rolling a shaped steel according to claim 1, wherein
[Claim 3]
The shaped steel according to claim 1 or 2, wherein after controlling the rotation speeds of all the rolling mills Ri of the rolling mill row, rolling is performed by fixing the rotation speed ratio of each rolling mill Ri. Rolling method.
[Claim 4]
The shaped steel according to claim 3, wherein the rolling speed of the rolling mill Rn at the most downstream of the rolling mill row is increased to a desired speed while the rotation speed ratio of each rolling mill Ri is fixed. Rolling method.
[Claim 5]
A rolling mill train composed of at least three rolling mills and n rolling mills, and at least one rolling mill or rolling mill trains are arranged in tandem in this order. A manufacturing line for shaped steel that performs rolling between the horizontal roll side surface and the vertical roll peripheral surface, in which the
tension-free control of the material to be rolled is performed in the upstream rolling mill row, and after the tension control has been completed, upstream of the rolling mill train and downstream of the rolling mill or rolling mill train in the presence of a sufficient distance for the rolled material is caught downstream of the rolling mill or rolling mill train are arranged,
the An upstream rolling mill train and the downstream rolling mill or rolling mill train are independently subjected to the method for rolling shaped steel according to any one of claims 1 to 4, Shaped steel production line.
[Claim 6]
A method for producing a shaped steel produced by performing a reduction between a side surface of a horizontal roll and a peripheral surface of a vertical roll
, wherein each rolling machine is a rolling mill train including at least three n rolling mills. Regarding Ri, the number of revolutions of the rolling mill Ri after the material to be rolled bites into the rolling mill Ri and before the material to be rolled bites into the rolling mill Ri+1 located downstream of the rolling mill Ri.
Is fixed, the rolling torque Gi of the rolling mill Ri at that time is stored as Gi * , and after the material to be rolled bites into the rolling mill Rn at the most downstream of the rolling mill row, it is located upstream of the rolling mill Rn. The rolling torque Gn-1 of the rolling mill Rn-1 is equal to the Gn-1 * stored as the rolling torque of the rolling mill Rn-1 before the material to be rolled is engaged in the rolling mill Rn. The first control step that controls the number of rotations
of the rolling mill Rn and the rolling torque Gn ** of the rolling mill Rn after the first control step are stored, and
then located upstream of the rolling mill Rn-1. So that the rolling torque Gn-2 of the rolling mill Rn-2 becomes equal to Gn-2* stored as the rolling torque of the rolling mill Rn-2 before the material to be rolled bites into the rolling mill Rn-1. In addition, the number of rotations of the rolling mill Rn-1 is controlled, and the number of rotations of the rolling mill Rn is controlled so that the rolling torque Gn of the rolling mill Rn becomes equal to the stored rolling torque Gn **. A second control step,
wherein the second control step is applied to all of the rolling mills Ri, and the rolling torque G1 of the most upstream rolling mill R1 is engaged with the rolling mill R2 located downstream of the rolling mill R1. Shaped steel is manufactured by controlling the number of revolutions of each rolling mill Ri of the rolling mill train so as to be equal to G1* stored as the rolling torque of the rolling mill R1 before the rolling. Steel manufacturing method.