JPH0211202A - Manufacture of steel sheet whose thickness having slope in width direction - Google Patents

Abstract

PURPOSE:To improve the quality and accuracy of product steel sheets by measuring thicknesses of edges and the central parts of a rolled stock, calculating a wedge and a crown ratios, then performing plural passes rolling with their ratios kept constant, respectively. CONSTITUTION:A business computer 8, process computer 9, and plant controller 10 are installed for roll chocks 6, 7 at driving and operating sides and a thickness gage 12 is installed near to a rolling mill, a finish rolling stage is performed after diagonal hot rolling in the rolling direction by a reversible rolling mill. In that time, thicknesses in edges and the central parts of a rolled steel sheet 1 are measured by the gage 12, a wedge and a crown ratios are calculated by a prescribed equation, and a gap between rolls 2, 3 is adjusted to keep those ratio constant. Thus, the quality and the shape and dimensional accuracy of product steel sheets are improved because a draft setting accuracy per pass is improved.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for rolling a steel plate having a thickness gradient in the width direction, and relates to a method for rolling a steel plate having a thickness gradient in the width direction, and is applicable to rolling of a steel plate having a thickness gradient in the width direction. This invention relates to the production of steel plates that are advantageous in terms of construction and structure because the plate thickness changes smoothly in the width direction depending on the required strength, as in the case of the members of the section.

[Conventional technology]

As a manufacturing method for a steel plate having a thickness gradient in the width direction, the first step is to roll a material to be rolled with a thickness gradient in the rolling direction, and then rolls are rolled with a gap difference in the roll axis direction. A rolling method (Japanese Patent Publication No. 52-1381) has been proposed in which rolling is performed in combination with a second step of rolling.

Furthermore, when performing roll reduction parallel to the widthwise inclination of the steel plate, the value of (thick side thickness/thin side limit) of the material at the start of rolling is (thick side thickness/thin side limit) of the steel plate at the end of rolling. A rolling method for a steel machine having a thickness gradient in the width direction with less camber (Japanese Unexamined Patent Publication No. 49-74)
No. 150).

[Problem to be solved by the invention]

In the conventionally proposed rolling method (Japanese Patent Publication No. 521381), in the second stage of rolling using rolling rolls with a gap difference in the roll axis direction, a constant reduction rate,
Alternatively, it is said that rolling is performed with a constant reduction amount, but in order to roll while completely maintaining a constant reduction ratio on the left and right sides for each pass, (thick side thickness - thin side thickness) / thin side There is a need for technology to accurately grasp the wedge ratio (hereinafter referred to as wedge ratio) for each pass and reflect that value in the adjustment of the left and right roll gap with high precision. , it is impossible to minimize the camber of rolled material,
As a result, the yield is significantly reduced, so it is not put into practical use.

In addition, when rolling with a constant reduction amount (Japanese Patent Application Laid-Open No. 4974150
In the method disclosed in Japanese Patent Publication No. 2003-121003, a large camber occurs during the rolling process, and it is difficult to predict and correct it, so that the yield similarly decreases significantly.

Furthermore, in any rolling method, in order to ensure a flat shape of the rolled material, it is necessary not only to maintain a constant wedge ratio in all rolling passes, but also to maintain a constant crown ratio in the lower rolling passes. However, no countermeasures have been devised for this technique, and if the conventional rolling method is used as it is, there is a problem that waves and warpage will occur in the rolled material.

In order to solve the above-mentioned problems, the present invention provides a method for efficiently rolling a steel plate having a slope in thickness in the width direction without camber, with good shape and dimensional accuracy, using ordinary rolling equipment. The purpose is to provide

[Means for Solving the Problems and Their Effects] The present invention will be described in detail below.

In order to achieve the objective of providing a method for efficiently rolling a steel plate having a thickness gradient in the width direction without camber and with good shape and dimensional accuracy, gamma rays are applied between rolling passes. The thickness of both edges and the center of the rolled material is actually measured using a radiation-based thickness measuring device such as , and the wedge ratio and crown ratio are calculated from these measured values, and both of these are The rolling process is characterized in that rolling is performed by adjusting the gap between the left and right rolls with high precision through computer-controlled processing so that the gap between the left and right rolls is always kept constant.

All of these series of roll gap setting controls are automatically processed using a computer in a short period of time between rolling passes, and the calculation results are used in an equipment configuration that allows the hydraulic reduction device to be operated directly from electrical signals. .

FIG. 1 is an explanatory diagram showing a control device for implementing the method of the present invention. In FIG. 1, the rolled material 1 is shown in a predetermined inclined rolling state by upper and lower rolling work rolls 2 and 3, reference numerals 4.5 and 6.7 are respectively backup rolls and drive-side and operation-side roll chocks.

A rolling control device for adding rolling blades to the drive side and operating side roll chocks 6.7 is a business computer 8 that stores information on the rolled material online, and receives this rolling material information for rolling control. It includes a process computer 9 that performs arithmetic processing for this, a plant controller (automatic rolling setting device) 10 that operates a rolling control system as an inclined rolling signal from the calculation results, and a hydraulic rolling device 11.

Furthermore, with the thickness measuring device 12 using gamma rays,
Immediately before or after rolling, both edges (H
l, H:l) and the plate thickness of the center part (F2),
The actual measurement information is transmitted to the process computer 9 and the reduction control is corrected.

Hereinafter, the implementation procedure of the present invention will be explained.

The slab used in the present invention is first heated to a predetermined temperature in a heating furnace, and then scale on the surface of the slab is removed.

FIG. 2 is an explanatory diagram showing a rolling procedure for carrying out the present invention.

The heated slab is rolled several passes in the elongated direction using one or more reversible rolling mills, and is rolled to a predetermined length (a). At this time, if the width of the product is wide and approximately the same as the length of the slab, the product may be rotated 90 degrees on the entry side of the rolling mill and rolled in the width direction.

Thereafter, it is rotated 90 degrees on the entry side of the rolling mill and export rolled to a predetermined width and thickness (b). Next, rolling is performed to add an inclination to the plate thickness in the rolling direction in the final pass to several passes of export rolling (C).

After width rolling, the slab is rotated 90 degrees again, and while maintaining a constant rolling reduction in the width direction, the length of the slab is increased and at the same time the thickness is decreased, resulting in a thickness slope in the width direction of the target dimension. Obtain a steel plate (d).

Next, among the pass schedules in export rolling, the calculation flow for the rough rolling extension manual taper rolling schedule is shown in FIG. 3.

The process computer 9, which has received the rolled material information from the business computer 8, calculates the maximum amount of inclination that can be added based on the equipment process capacity, and then calculates the inclination rate in the rolling direction that should be applied after the completion of widthwise rolling (plate ■Calculate thickness difference/plate width) and plate thickness.

The plate thickness difference (W: wedge amount) at this time is determined so as not to cause camber in the rolling process (hereinafter referred to as finish rolling process) with the rolls being inclined in the rolling direction. That is, in the finish rolling process, rolling with a constant wedge rate is required, and therefore, even in rough rolling, the wedge amount is added in the rolling direction so that the following formula is satisfied.

(W/H)=(w/h)+K...(1)
However, W: Difference in plate thickness at the end of axial rolling (thick thickness - thin thickness) H: Thin plate thickness at the end of axial rolling W: Difference in final finished plate thickness (thick thickness - thin thickness) h: Final finished thin plate Next, calculate the rolling reaction force and torque limit, and then calculate the plate thickness on the entry side of this export tilt rolling and the amount of reduction during biting and ash removal.

In the rolling process that adds an inclination to the rolling direction, the roll gap is created by operating a hydraulic rolling device to widen or narrow the gap as the roll rotates with the progress of the rolled material, that is, correcting the advance rate.■■■ .

The operation amount ΔSO under hydraulic pressure at this time is calculated by predicting Sol and So2 from the following using a known gauge meter 2, Δ5o=Sol −3o2 ・” (3
), give.

However, I (1: Plate thickness Fl when biting: Rolling load Sol when biting: Roll gap F2 when biting: Plate thickness F2 when removing ash: Rolling load So2 when removing ash: Roll gap M: Mill rigidity The calculated hydraulic pressure reduction operation amount ΔSo is transmitted from the process computer 8 to the plant controller 9, and the oil column of the rolling mill is operated to obtain the target inclination ratio.

The pass schedule before inclined rolling at the width ratio is calculated by stacking the passes from the bottom in order from the narrow width pass to the adjusting thickness pass to determine the entire pass schedule from the slab.

Next, FIG. 4 shows a calculation flow for the width direction taper rolling pass schedule in the finish rolling process.

The process computer 9 receives the rolled material information necessary to determine the left and right roll gap values from the business computer 8. First, the process computer 9 predicts the finishing temperature of the rolled material based on the target left and right finished plate thicknesses. ■. Furthermore, after calculating the target plate crown amount and plate wedge amount (■), the number of lower rolling passes that require shape control rolling is determined in advance (■).

Next, after calculating the current rolling roll profile,
, predict and calculate the total rolling load required to obtain the target plate crown amount.

The amount of plate crown is determined by the amount of roll bending and roll wear due to rolling load, and the amount of expansion due to rise in roll temperature. Therefore, the roll profile and the target plate crown amount are determined in advance.
, and ■ or ■: The rolling load F is calculated using the formula:

However, F: Total left and right rolling load CR: Target exit plate crack Un 80w: Work roll crown (Initial + expansion - wear) ΣCb 2 back unroll (Initial expansion - wear) B: Rolling width ri: Work roll diameter ri: Backup roll diameter 0 ", J: Offcent term It is.

When calculating the pass schedule in advance before rolling, as described in section (■) below, the target plate crown on the exit side of the previous pass is determined so that the crown ratio for each pass does not change, and then The rolling load of each pass is predicted by stacking up from the final pass to the upper pass.

Furthermore, between passes during actual rolling,
Using a thickness meter that uses radiation such as gamma rays, measure the center and edge thickness of the rolled material, and calculate the plate crown: CR nibrate crown amount Hl: Thin edge thickness H2: Center thickness I]3: Thickness The actual plate crown is evaluated as the part edge thickness, and according to the relationship between the actual crown measurement value and the actual rolling load, the Of and term in equation (3-1) are automatically corrected, and equation (3-1) is calculated. Improve the accuracy of load crown prediction.

At the same time, as the plate wedge amount, Wg=H3−H
l ... (3-3) Wg; Plate wedge amount Hl: Thin part edge thickness H3: Thin part edge thickness H3: Evaluated as thick part work, Tsujida thickness, and in equation (7) described later, calculate the roll gap from the respective rolling loads on the left and right sides. In the process of calculation, the OR of equation (7) is calculated depending on the relationship between the actual thickness of the edge portion and the actual roll gap with respect to the actual load.

■ Automatically corrects the terms and improves the accuracy of the model that determines the roll gap.

After determining the total rolling load using equation (3-1), the average rolling reduction ratio is then calculated.

The average rolling reduction ratio: T is determined using the following prediction formula that incorporates the deformation resistance and rolling force function from the temperature and plate thickness of the rolled material.

An (Ft) −B (afn (T)+b)−(
4) However, F, Nidotal rolling load b = Rolling width γ: Average rolling reduction a, b: Coefficient (function of rolling temperature, rolling exit side plate thickness) Here, in the finish rolling process, camber is not caused. In order to roll to
as/Hns) ”・(5) must hold. Here, T: Average rolling reduction rate ΔH S: Operating side rolling amount H ; Operating side outlet side plate thickness ΔHos: Drive side rolling amount Hos: Driving This is the thickness of the side plate.

From equation (5), the left and right reduction amount; ΔHW*rΔ)Ios is determined, and the left and right entry side plate thicknesses are calculated.

Furthermore, the respective rolling loads on the left and right sides during non-balanced rolling in the finish rolling process can be predicted by distributing and integrating the rolling load per unit width to the left and right sides. That is, B: Rolling width fX: Rolling load per unit width at point x a: Distance from the rolling mill operating side chock center to X point b; Distance from the rolling mill driving side chock center to X point L: Rolling This is the distance between machine chock centers.

From the left and right rolling loads predicted by equation (6), calculate the roll gap using the gauge meter formula for each of the left and right sides. Side rolling load M, 5: Operating side mill rigidity 3o (,, B: Drive side roll gap Ho: Drive side outlet plate thickness Fos: Drive side rolling load M, 5: Drive side mill rigidity Ofs,, s , 0f-1) -: Offsen 1- (correction term) At this time, by actually measuring the edge thickness, the roll gap during the next rolling is automatically corrected against the calculated predicted value to improve the plate thickness accuracy. 0 that can be improved
The left and right roll gap values calculated from the above process are transmitted from the process computer 9 to the plant controller 10, and the hydraulic rolling machine 11 of the rolling mill is operated from the electrical signal, and the gap value between the left and right rolls is calculated with high accuracy and efficiency for each pass. ■ [Phase] can automatically set the pressure reduction.

Calculation of each roll gap value is performed sequentially from the final finishing pass, assuming a constant crown ratio and constant wedge ratio. Calculate the inlet plate thickness from the exit plate thickness and reduction amount, and then use it as the exit plate thickness of the previous pass. ■ 0 @ 10 In addition, in upper rolling passes that do not require shape control rolling, the logic of constant crown ratio is excluded, and the rolling load or rolling torque is calculated by stacking up the entire pass schedule from the bottom. Determining the pass schedule for rolling 0° [Example] Next, an example will be shown in which a steel plate having a thickness slope in the width direction was rolled according to the above-described procedure of the present invention.

Example 1 Material: 5S41, board width: 3000+u, thickness of both edges in the width direction: 19.25 m and 20.75 mm, respectively.
A steel plate having a plate length of 15,000 mm and a thickness gradient in the width direction was manufactured by the following method.

Dimensions Width 1320m5, Length 298On+, Thickness 242n
A slab produced by continuous casting was heated to 1200°C and rolled to the following hot dimensions.

Longitudinal rolling thickness 172.5 wet seal 344 Yanen length 4300
■Rolling in the width direction (before adding slope) Thickness 79.81++m Width 2864mm Length 43
00mm width by direction rolling (inclined addition) Thin part thickness 69.84 m Thick part thickness 75.28 am Width 3150 m Length 4300 m Next, the calculated values and actual values of the pass schedule in the finish rolling process according to the present invention and, For comparison, the first example of the pass schedule and the change in the occurrence of camber to achieve the target plate thickness using the conventional method of constant pressure top rolling are shown below.
Shown in the table.

The actual values shown in Table 1 below are the plate thicknesses estimated using the gauge meter formula from the actual set actual roll gap and actual rolling load, while the calculated values are based on the method of the present invention. This is the predicted path schedule calculation value.

The accuracy of the measured plate thickness with respect to the target plate thickness of the obtained rolled material is shown in FIG. Further, the amount of camper over the entire length, flatness, and rolling yield are shown in Table 2 in comparison with the conventional method.

Table 2 Example 2 Material L32A (Lloyd's Register Standard: 50 steel for shipbuilding, online controlled cooling performed), plate width 3,000 mm, width side edge thickness 13.0 (bm, 1).
A steel plate having a plate thickness of 4.00mm and a plate length of 16B00mm and having a thickness slope in the width direction was manufactured by the following method.

A slab having dimensions of 2200mm width, 2770mm length, and 120mm thickness was heated to 1150°C and rolled to the following hot dimensions.

Longitudinal rolling thickness: 79.0 mm Width: 2224 m Oboro Length: 4300 mm Width direction rolling ((before lJi diagonal addition) Thickness: 59.80 ml Width: 2938 mm Length: 430
0 Rolling in width direction (addition of slope) Thin part thickness 52.47 Thick part thickness 56.511 Width 323
Table 3 shows the calculated values and measured values of the pass schedule in the finish rolling process according to the present invention, as well as the changes in the occurrence of camber. Furthermore, for comparison, Table 3 also shows the pass schedule when computer control is not performed for the target plate thickness.

Note that the plate thickness accuracy at this time was assumed to vary by an error of 3% with respect to the target.

Below #white Table 3 It is shown in Table 4.

Table 4 Furthermore, the changes in the occurrence of camber amount are compared with the conventional method and are shown in FIGS. 7(A) and 7(B) for Examples 1 and 2, respectively.

Values with similar definitions.

The accuracy of the measured plate thickness with respect to the target plate thickness of the obtained rolled material is shown in FIG. In addition, the amount of camber in the entire length and the actual flatness were compared with the conventional method.
By implementing the present invention, a technology that can adjust the gap between the left and right rolls with high precision and efficiency has been established, and rolling can be performed while perfectly maintaining a constant reduction ratio on the left and right sides for each pass. It is possible to minimize the camber of the material. As a result, the rolling yield is comparable to that of ordinary parallel steel plates.

Further, it becomes possible to roll the rolling material while keeping the crown ratio constant in the lower pass, and it is possible to solve the problem of occurrence of waves and warpage in the rolled material.

As described above, the present invention is capable of rolling a steel plate having a slope in thickness in the width direction, which can be applied to any material and size using ordinary rolling equipment, efficiently, without camber, and with good shape and dimensional accuracy. This is an invention that allows

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the control device in the finish rolling process of the present invention, FIG. 2 is a schematic diagram showing the rolling method of the present invention, and FIG.
The figure is a flowchart showing the calculation process for determining the roll gap up to the axial rolling process, Figure 4 is a flowchart showing the calculation process for determining the roll gap in the finish rolling process, and Figure 5 is the calculation process for determining the roll gap in the finish rolling process. A diagram showing the thickness distribution in the width direction of the steel plate in Example 1, Figure 6 is a diagram showing the thickness distribution in the width direction of the steel plate in Example 2, and Figure 7 (A) (I3) shows the occurrence of camber amount. It is a diagram showing the transition of the situation. ■... Material to be rolled, 2... Upper work roll, 3... Lower work roll, 4... Upper hack up roll, 5... Lower back up roll, 6... Upper roll chock, 7 ...Lower roll chock, 8...Business computer, 9...Process computer, IO...Plant controller, 11...Hydraulic lowering device. Diagram: Bin failure computer diagram (A) Number of passes diagram (B)

Claims (1)

[Claims] 1. When rolling a steel plate with a thickness slope in the width direction, the rolled material with a thickness slope in the rolling direction is rotated 90 degrees to reduce the difference in the roll gap in the roll axis direction. In the method of rolling a steel plate having a slope in thickness in the width direction by changing the gap between each rolling pass, the rolled material is rolled with a constant wedge ratio and crown ratio. A method for producing a steel plate having a thickness gradient in the width direction, the method comprising rolling the steel plate in multiple passes while holding the plate. 2. When rolling a steel plate whose thickness is inclined in the width direction, the rolled material whose thickness is inclined in the rolling direction is rotated 90 degrees to create a difference in the roll gap in the roll axis direction, and the gap is In a method of rolling a steel plate having a thickness gradient in the width direction by changing the thickness at each rolling pass, the finishing temperature of the rolled material is predicted from the target final finished plate thickness, and the target plate crown amount is calculated. and plate wedge amount, determine the number of rolling passes from these, then predict and determine the total rolling load from the plate crown and plate wedge at the exit side of each rolling pass, calculate the average rolling reduction from this, and calculate the number of rolling passes from these. The roll gap value is calculated by predicting the rolling amount and rolling load in the width direction of the rolled material, and at this time, the predicted value of the roll gap is corrected by measuring the edge thickness, and the crown ratio is calculated for each rolling pass. and the roll gap value is adjusted and introduced into the control system so that the wedge ratio is always kept constant, and the hydraulic rolling device of the rolling mill is thus activated to roll the material to be rolled in multiple passes. A method of manufacturing a steel plate having a thickness gradient in the width direction. 3. When predicting the plate crown and plate wedge on the exit side of the rolling mill, the predicted value is automatically corrected at the next rolling time based on the plate crown amount and plate wedge amount actually measured before and after rolling with a thickness gauge. The method according to claim 2.