JP3433567B2 - Rolling method of taper plate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling method suitable for manufacturing a tapered plate using a thick metal plate such as a thick steel plate. [0002] In the fields of shipbuilding and bridges, etc.
In order to reduce the weight of the structure, an optimum thickness design according to the required strength is performed. For this purpose, steel plates having different thicknesses are generally connected by welding. By the way, in this method, the man-hours required for the welding work, the man-hour increase due to the modification of the deformation due to the welding, and the material cost increase due to the increase in the number of members were inevitable. As a method for solving such a problem, in recent years, a so-called tapered plate (taper plate) in which the thickness of a steel plate is changed at a constant rate in a rolling longitudinal direction at a rolling stage has been used. This has enabled a significant reduction in manufacturing costs. The target thickness of the tapered plate at each position in the length direction is determined by its specifications. Therefore, when a taper plate having a predetermined shape in accordance with specifications is manufactured by rolling, the product quality (dimensional accuracy) and yield are controlled by a gap control of a work roll according to a target plate thickness at each position in the rolling direction. It depends on the quality. In other words, it is necessary to increase the accuracy of predicting the elongation of the rolling and to perform the predetermined rolling at a more accurate position in the rolling direction. From such a thing,
Prediction of pressure elongation is an important control factor when rolling taper plates. [0005] By the way, in order to predict the pressure extension, a general method that has been conventionally employed is to measure the number of rotations of a roll by a pulse generator installed on a work roll, and calculate the following (1) from the number of rotations. ) Formula: L = π × DW × θR × (1 + φ (r)) (1) where L: pressure extension DW: work roll diameter θR: work roll rotation speed φ (r): prediction formula The advance rate is calculated using the calculated advance rate, and the advance rate φ (r) often employs an advance rate prediction formula. [0006] As described above, in the conventional taper plate rolling, the prediction accuracy of the pressure elongation depends on the calculation accuracy of the advanced rate prediction formula. However, when predicting the elongation using the advanced rate prediction formula, errors in the prediction of roll flatness and errors due to the effect of the friction coefficient between the roll and the rolled material occur. There is a problem that an adverse effect (for example, an error of about 100 mm) is exerted. In addition, it is conceivable to directly measure the elongation by using a measuring roll or a laser Doppler plate speed meter without using the above formula (1). However, hot rolling such as taper plate rolling can be considered. Under the conditions, the measurement is difficult, and there is a problem that the pressure extension cannot be measured accurately in actual operation. SUMMARY OF THE INVENTION An object of the present invention is to overcome the problems of the above-mentioned known art. By improving the accuracy of predicting the elongation of a pressure, a taper plate having good dimensional accuracy and high yield can be stably obtained. Is to propose a rolling method that can be manufactured. Means for Solving the Problems In order to achieve the above object, a solution proposed by the present inventors is to install two or more plate edge detecting devices separated from each other in the rolling direction, and to use these devices. Calculate the actual passing rate by the ratio with the work roll rotation speed, and correct the advanced rate prediction formula used for the prediction of the pressure elongation by the obtained advanced rate. This rolling method improves the accuracy of predicting the elongation by rolling using the rolling method, and performs the rolling reduction at a more accurate rolling direction position. That is, according to the present invention, in rolling a taper plate by changing a work roll gap in accordance with a length position in a rolling direction, two or more plate edge detecting devices are provided downstream of a rolling mill. In the initial stage until the leading end of the rolled material reaches the plate edge detection device located further downstream, rolling is performed using a predetermined advanced rate prediction formula, and then the leading end of this rolled material is After passing through the plate edge detecting device located on the downstream side, the average threading speed between the plate edge detecting device and the plate edge detecting device located on the more upstream side is calculated, and the calculated average threading speed is obtained. A method for rolling a tapered plate, wherein the advanced rate prediction formula is corrected using a plate speed and a work roll rotation speed, and rolling is performed using the corrected advanced rate prediction formula. Hereinafter, the method of the present invention will be described in detail. Generally, in the rolling of a tapered plate, it is necessary to control the plate thickness at each position in the rolling direction to a target value. Forecasting is important. The pressure extension L at this time is basically predicted by using the following equation (2), a roll gap is set in accordance with each predicted pressure extension, a target taper is accurately given, and a yield is increased. It is intended to improve the quality. 1) Until the initial stage of the rolling, that is, until the rolled material reaches the plate end detecting device located further downstream among the plate end detecting devices provided on the downstream side of the rolling mill, Rolling is performed with the advanced rate correction coefficient α set to 1.0. 2) After the leading end of the rolled material reaches the above-described downstream side plate edge detection device, the downstream side plate edge detection device and the more upstream side plate edge are detected. The advanced ratio correction coefficient is obtained by using the plate edge detection signal obtained from the detection device, and the rolling is performed by correcting the equation (2) to improve the accuracy of the elongation. L = π × Dw × θr × (1 + α × φ (r)) (2) where L: pressure extension Dw: work roll diameter θr: work roll rotation speed α: correction coefficient φ (r ): The advance rate (reduction rate r is a parameter) determined by the prediction formula. The above α is defined by the following equation (3). α = φt / φm (3) where φt: actual average advance rate between plate edge detectors φm: average advance rate between plate edge detectors calculated by a prediction formula, φt, φm Are respectively obtained from the following equation (4). φt = Vp / Vr−1 (4) Vp: average sheet passing speed between sheet edge detecting devices (= distance between sheet edge detecting devices / time required to pass between sheet edge detecting devices) Vr: average rotation speed of the work roll obtained by the pulse generator φm = ∫φ (r) dt / t (5) φ (r): advanced rate obtained by the prediction formula (rolling rate r changes with time) t: Time required to pass between the plate edge detecting devices. An advanced rate predicting equation for predicting the advanced rate φ (r) is, for example, φ (r) = [R ′ / ｛( 1−r) · h ₁ ｝] · φ ² _n , φ _n = (１ ／) · φ ₁ · (1−φ ₁ / 2μ) (6) where h ₁ : entry side thickness R ': Flat roll radius φ _n : neutral angle φ ₁ : contact angle μ: there is a coefficient of friction. In the present invention, at least two sheet edge detecting devices are provided on the downstream side of the rolling mill and are spaced apart from each other in the rolling direction. It is effective to take measures such as increasing the number of plate edge detection devices to three or more and reducing the installation interval between the plate edge detection devices. When three or more detectors are added, every time they pass the downstream detector,
The advance rate is predicted by equation (4), the correction coefficient α is corrected by equation (3), and the accuracy of equation (2) is improved. In addition, it is preferable to set the installation interval between the respective plate edge detection devices in a range of about 1 to 3 m. The distance between the rolling mill and the sheet edge detection device closest to the rolling mill is preferably set in a range of about 1 to 3 m. FIG. 1 shows a system configuration suitable for use in the present invention, in which two plate edge detectors are provided. In the drawing, reference numerals 1 and 2 denote plate edge detection devices, and 1 is provided on the upstream side and 2 is provided on the downstream side. 4 is a process computer, 5 is a load cell, 7 is a hydraulic cylinder,
Reference numeral 8 denotes a work roll, and 3 denotes a pulse generator for measuring the rotation speed of the work roll 8. When the taper plate rolling is performed by the above system configuration, first, in the initial stage of the rolling, that is, in the rolling until the leading end of the rolled material 11 reaches the downstream end detecting device 2, a predetermined rolling is performed. advanced ratio prediction equation, using information S _P output pulse generator, (2) 1.0 advanced correction coefficient α of formula by a process computer 4 obtains the rolling length. On the other hand, target thickness of information in the rolling length from the host computer not shown, based on the load information S _L from the load cell 5, performs the computation of the roll gap by the process computer 4 using the gauge meter equation 6 Direct Digital Controller (DD)
Rolling is performed by adjusting the gap of the work roll 8 by setting the position of the cylinder 7 via C). Next, after the leading end of the rolled material 11 arrives at the plate edge detecting device 2 on the downstream side, each of the rolled material 11 obtained from the two plate edge detecting devices of the plate edge detecting device 1 and the plate edge detecting device 2 is used. From the sheet edge detection signals S _E1 and S _E2, an average sheet passing speed between the sheet edge detection devices is obtained, and this speed and information S of the pulse generator are obtained.
_From the average rotation speed of the work roll obtained from _P ,
According to equation (4), the actual average advance rate φt between the plate edge detection devices is
Is calculated. Separately from this, the average advanced ratio φm between the plate edge detecting devices 1 and 2 is obtained by using the expression (5) by the advanced ratio prediction expression of the expression (6). The advanced ratio correction coefficient α is calculated from the values of both advanced ratios obtained by the above formula according to the formula (3), the advanced ratio prediction formula is corrected with the α, and the rolling length is obtained from the formula (2). I do. In this case, the method of adjusting the gap of the work roll 8 is performed in the same manner as described above. As described above, according to the present invention, the accuracy of predicting the advance rate of a sheet during rolling and the accuracy of calculating the elongation of a sheet are improved, and the reduction in taper rolling can be set more accurately. This can be performed at the directional position. Therefore, according to the present invention, a tapered plate having good dimensional accuracy can be stably manufactured, which greatly contributes to improvement in yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an example of a system configuration for manufacturing a tapered plate. [Description of References] 1 Plate edge detection device (upstream side) 2 Plate edge detection device (downstream side) 3 Pulse generator 4 Process computer 5 Load cell 6 Direct digital controller (DDC) 7 Hydraulic cylinder 8 Work roll 9 Backup roll 10 Servo valve 11 Rolled material

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 1/00-1/46 B21B 37/00-37/78

Claims (1)

(57) [Claim 1] In rolling a taper plate by changing a work roll gap according to a length position in a rolling direction, two or more plates are provided downstream of a rolling mill. The edge detection device is provided at a distance in the rolling direction, and the initial stage until the leading end of the rolled material reaches the plate edge detection device located on the downstream side is rolling using a predetermined advanced rate prediction formula, and then After the point at which the leading end of the rolled material has passed through the plate edge detection device located on the downstream side, determine the average sheet passing speed between the plate edge detection device and the plate edge detection device located on the more upstream side, A method for rolling a tapered plate, comprising: modifying the advanced rate prediction formula using the calculated average threading speed and the work roll rotation speed; and rolling using the modified advanced rate prediction formula.