JP3370881B2 - Hot straightening method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hot straightening a thick plate by a roller leveler. [0002] Conventional hot straightening methods of this type include:
There is known a method of compensating and controlling a leveler elongation obtained by a leveler constant under a hydraulic pressure with respect to a load generated at the time of straightening. [0003] However, in such a straightening method, when straightening a thick steel sheet in which end warpage is likely to occur in a finished rolled shape, the load at the warped portion of the steel sheet is reduced. Unnecessary processes such as pressing to remove the distortion defective portion due to the occurrence of a large distortion defective portion in the steel plate abandoning the correction in the middle to exceed the dangerous load region on the constraint, and, There is an inconvenience that equipment may be damaged by use at the limit of equipment restrictions. SUMMARY OF THE INVENTION The present invention has been made in order to solve such inconvenience, and an object of the present invention is to provide a hot straightening method that can eliminate the need for correction and prevent damage to equipment. [0005] In order to achieve the above object, a hot straightening method according to the present invention is a method for hot straightening a thick plate by a roller leveler. When performing compensation control of the amount of elongation, a non-control region that is set in advance according to the amount of distortion of the thick plate before straightening is set within the dangerous load region determined due to facility restrictions ,
Overload occurs due to warpage of the end of the thick plate during straightening
The leveler elongation when entering the uncontrolled area
The compensation control is stopped to suppress the correction load . An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory schematic diagram illustrating a roller leveler used in a hot straightening method according to an embodiment of the present invention, FIG. 2 is an explanatory graph diagram illustrating an uncontrolled area, and FIG. Is the hydraulic pressure reduction servo valve Ref
FIG. 5 is a graph showing a relationship between a control amount of hydraulic pressure reduction (ARGC) and a correction load. First, the basic structure of the roller leveler will be described with reference to FIG.
A plurality of rolls 3 are vertically arranged along the traveling direction of the thick steel plate 2. The upper plurality of rolls 3 are rotatably supported by the upper frame 4, while the lower plurality of rolls 3 are rotatably supported by the lower frame 5. The upper and lower frames 4 and 5 are disposed in a housing 6, and the upper frame 4 is provided in the housing 6 by an electric pressing device 7 and a hydraulic pressing cylinder 8 interposed between the electric pressing device 7 and the upper frame 4. Can be moved up and down. In addition, the electric screw-down device 7 and the hydraulic screw-down cylinder 8
Are disposed on the front side and the rear side, respectively, in the traveling direction.
Further, a flatness meter 9 for detecting the amount of end warpage of the thick steel plate 2 before straightening is disposed on the front side in the traveling direction of the thick steel plate 2. Each hydraulic pressure lowering cylinder 8 is provided with a pressure cell 10 for measuring the load on the front surface and the rear surface of the thick steel plate 2 in the traveling direction at the time of straightening. The measured load value obtained by the pressure cell 10 is
The control device 11 controls the hydraulic pressure reduction cylinder 8 to reduce the leveler elongation amount by controlling the pressure reduction of the hydraulic pressure reduction cylinder 8 so that the load measurement value coincides with a preset correction load. When the dangerous load area A (see FIG. 2) set according to the strength of the equipment is exceeded, the load by the hydraulic pressure reduction cylinder 8 is released to prevent damage to each component of the leveler. Here, in this embodiment, as shown in FIG. 2, the uncontrolled area of the margin allowance α corresponding to the amount of end warpage of the thick steel plate 2 before straightening (after rolling) is set in the dangerous load area A. B (hatched portion) is provided, and within the range of the non-control region B, the compensation control of the leveler elongation by the control device 11 is stopped to suppress the load at the time of correcting the end warpage. The allowance α according to the amount of warpage of the end portion of the thick steel plate 2 is tabulated based on the empirical rule and the like between the allowance α and the amount of warpage of the end, stored in a storage area of the control device, and corrected. The table is set with reference to the actual warpage amount of the thick steel plate 2 detected by the flatness meter 9 before. Next, a hot straightening method which is an example of an embodiment of the present invention will be described. The flat steel sheet 2 passed between the upper and lower rolls 3 detects the end warpage amount by the flatness meter 9 before straightening, and refers to the storage table of the control device 11 based on the warpage amount to determine the uncontrolled area B. The allowance α is set. At the time of passing the sheet, the upper frame 4 is lowered by the electric pressing device 7, and the thick steel plate 2 is straightened while being repeatedly bent by the initial intermesh of the upper and lower rolls 3.
At the time of correction, until the load measurement value obtained by the pressure cell 10 enters the non-control area B, the control device 11 controls the hydraulic pressure reduction cylinder 8 to reduce the load so that the load measurement value matches the set correction load. To perform compensation control of the leveler elongation. When an overload occurs due to the end warpage of the thick steel plate 2 and the measured load value enters the non-control region B, the control device 11 stops the leveler elongation compensation control and suppresses the correction load. I do. If the load measurement value exceeds the dangerous load area A when the compensation control is stopped, the control device 11 releases the load from the hydraulic pressure reduction cylinder 8. As described above, in this embodiment, when an overload occurs due to the end warpage of the thick steel plate 2 during straightening and enters the non-control region B, the compensation control is stopped to suppress the straightening load. As a result, the load at the warped portion of the thick steel plate can be prevented from exceeding the dangerous load area A due to facility restrictions. The occurrence of a portion can be prevented. Further, since the load at the warped portion of the thick steel plate does not exceed the dangerous load area A due to the facility restriction, it is possible to avoid use at the limit of the facility restriction. it can. FIG. 3 shows the hydraulic pressure reduction servo valve Re in this control.
The relationship between f, the hydraulic reduction (ARGC) control amount, and the correction load is shown. (A) shows the control result of the front surface in the traveling direction of the thick steel plate, and (b) shows the control result of the rear surface in the traveling direction. As is apparent from the figure, when the correction load enters the non-control region B during the correction on both front and rear surfaces, the compensation amount under the hydraulic pressure becomes zero, and thereafter, the correction is stably performed with the suppressed correction load. You can see that In this embodiment, an example is described in which the compensation control is performed based on the difference between the load measurement value obtained by the pressure cell 10 and the set correction load value.
The present invention is not limited to this, and the present invention may be applied to other known compensation control. As is apparent from the above description, according to the present invention, it is possible to prevent the load at the strained portion of the thick plate from exceeding the dangerous load region due to facility restrictions. There is obtained an effect that it is possible to prevent the occurrence of a large defective deformation portion in the thick plate after the correction by eliminating the waiting for correction as in the related art. Further, since the load at the distorted portion of the thick plate does not exceed the dangerous load region in the equipment restriction, it is possible to avoid use at the limit of the equipment restriction, so that damage to the equipment can be prevented. The effect is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory schematic diagram for explaining a roller leveler used in a hot straightening method as an example of an embodiment of the present invention. FIG. 2 is an explanatory graph for explaining a non-control area B; 3 is a graph showing a relationship between a hydraulic pressure reduction servo valve Ref, a hydraulic pressure reduction (ARGC) control amount, and a correction load, where (a) is a front surface in the traveling direction of the thick steel plate, and (b) is a rear surface in the traveling direction. 3 shows the control result. [Description of Signs] 1 ... Roller leveler 2 ... Thick steel plate 7 ... Electric pressure reduction device 8 ... Hydraulic pressure reduction cylinder 9 ... Flatness meter 10 ... Pressure cell 11 ... Control device A ... Dangerous load region B ... No control region

Claims (1)

(57) [Claims] [Claim 1] In a method of hot straightening a thick plate by a roller leveler, when a compensation control of a leveler elongation with respect to a load generated at the time of straightening is performed, it is determined due to facility restrictions. In the dangerous load area, a non-control area that is set in advance according to the distortion amount of the thick plate before correction is set, and the thick plate
An overload due to the end warpage occurs and the uncontrolled area
Stop the compensation control of the leveler elongation when entering
A hot straightening method characterized by suppressing a straightening load .