JPH10180325A - Plate camber controller in hot rolling of steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To straighten the plate generated during hot rolling of a steel plate by computing the grinding roughness of the steel plate surface required for forcing the plate camber detected with a plate camber detector and determining the feeding quantity of coating grain and the pressure of a high pressure fluid based on the operated result to control. SOLUTION: The camber quantity is detected with the plate camber detector 3 at the outlet side of a first stand and inputted into an arithmetic unit 4. In the arithmetic unit 4, a function (f) is calculated based on the output signal of the plat camber detector 3 and the rolling condition inputted from a rolling condition setting device 5, and the surface of the steel plate to be ground is determined in order to straighten the camber with rolling in the (i) path being a camber modifying path is determined, the pressure of the high pressure fluid and the jetting quantity of abrasive grain for giving the roughness are operated, and the value is outputted to a steel plate surface grinding controller 6. A control command is outputted to an abrasive grain feeding device 7 and a high pressure fluid feeding device 8 based on the value from the arithmetic unit 4 with the steel plate surface grinding controller 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to hot rolling of steel sheets,
In particular, the present invention relates to a sheet warpage control device for correcting a sheet warpage generated in thick plate rolling or hot rough rolling online.

[0002]

2. Description of the Related Art When warpage occurs during hot rolling of a steel sheet, equipment such as a strip guide is damaged in the case of a large warpage. Further, in the production of a heat-treated steel plate (TMCP), uneven cooling caused by warpage of the sheet causes a material defect or a residual strain.

[0003] Conventionally, as a method of preventing sheet warpage,
Various methods such as (1) a method of different peripheral speed rolling, (2) a method of moving the entry side table roller up and down to control the bite angle, and (3) a method of controlling the roughness of the upper and lower work rolls have been studied.

However, in the (1) different peripheral speed rolling method, it is difficult to make a large difference between the upper and lower work roll peripheral speeds due to the impact drop generated when the rolled material is bitten, and the warpage control effect is reduced. In addition, it is difficult to control the different speed ratio with high accuracy according to the plate thickness and the reduction ratio. Due to such a problem, the warpage of the steel sheet has not yet been completely prevented by the different peripheral speed rolling method. (2) In the pick-up amount control method, the amount of change in the pick-up amount is limited by the reduction of the rolling reduction and the plate thickness, so that it is difficult to obtain a large warpage control effect. There is a problem that it must be fixed.

[0005] The upper and lower work roll roughness control method (3) may have a large warpage control effect. Japanese Patent Application Laid-Open No. 61-049719 discloses that a roll attached to a rolling stand is A method is disclosed in which a grinding belt is pressed against upper and lower rolls and the roll surface is roughly ground in response to sheet warpage or sheet bending detected at the rolling exit side.
Further, according to Japanese Patent Application Laid-Open No. 06-7817, according to the sheet warpage detected on the entrance side or the exit side of the rolling mill, abrasive grains are sprayed on a work roll together with a pressure medium to control the work roll surface roughness. A method for preventing warpage is disclosed.

However, the method of controlling the roll surface roughness has a problem in that the roll grinding time required to change the roll surface roughness is long, so that it is impossible to follow the plate warpage that changes in each pass. There are problems such as deterioration of the basic unit of roll due to grinding, and the sheet warpage occurring in actual operation cannot be sufficiently prevented.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and provides a sheet warpage control device capable of correcting a sheet warpage generated during hot rolling of a steel sheet. The task is to

[0008]

The present inventors have focused on the difference in friction coefficient between upper and lower rolls during rolling, which is one of the causes of sheet warpage during rolling, and utilized the difference in friction coefficient. Various studies were conducted to develop a device for correcting warpage. As a result, a polishing abrasive spray nozzle is installed on the entry side of the rolling mill, the polishing abrasive is projected on one surface of the steel plate, and the plate warpage is corrected by imparting a difference in the roughness of the upper and lower surfaces of the steel plate. I got the knowledge that I can do it.

The present invention has been made based on such knowledge, and the gist of the invention is that a sheet warpage detecting device installed on the exit side of a hot rolling mill and an entrance side of a hot rolling mill are provided. Abrasive abrasive jet nozzle capable of grinding the entire width direction of the upper and lower surfaces of a steel plate, an abrasive supply device and a high-pressure fluid supply device for supplying abrasive and high-pressure fluid to the nozzle, and a plate warpage detection device An arithmetic unit for calculating the polishing roughness of the steel sheet surface necessary to correct the plate warpage detected by the method, and determining the abrasive supply amount and the pressure of the high-pressure fluid based on the calculation result, And a polishing controller for controlling the high-pressure fluid supply device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a description will be given of the warpage generation behavior when rolling is performed while changing the roughness of the steel sheet surface.

Document "Research on Machines" Vol. 47, No. 7, 6
As shown on page 8, the sheet warpage that occurs when the roughness of the steel sheet surface is changed to give a roughness difference between the front and back surfaces is as follows:
It may warp to the high friction coefficient side or warp to the low friction coefficient side.

That is, if the roll diameter and rolling reduction are small and the contact arc length is short, warpage occurs on the low friction coefficient side, and if the roll diameter and rolling reduction is large and the contact arc length is long, warpage occurs on the high friction coefficient side. Occur.

When warpage occurs in a steel sheet during rolling, in order to correct the warpage by changing the surface roughness of either the upper surface or the lower surface of the steel plate, it is immediately known which surface is to be roughened. There must be.

Therefore, the present inventors carried out experiments in which the rolling conditions were variously changed with respect to the amount of warpage generated in rolling in which a difference in friction coefficient was given between the upper surface and the lower surface of the steel sheet. The condition of warping toward the low friction coefficient side was determined as a function f of the roll diameter and the rolling reduction.

When a difference in the surface roughness of the steel sheet is to be imparted for the purpose of correcting the warpage, the rolling on the upper surface side is made rougher than that on the lower surface side in the rolling where f is smaller than 1.0. On the other hand, in the case of large rolling, it is possible to reduce sheet warpage by increasing the roughness on the lower surface side. Therefore, when warpage occurs during rolling, the surface to be roughened of the steel sheet can be determined by obtaining f.

FIG. 1 is a view showing an example in which the apparatus of the present invention is applied to a lever mill of a plate rolling mill or the like.

The apparatus according to the present invention comprises: a plate warpage detecting device 3; polishing abrasive jet nozzles 9a and 9b for polishing;
The apparatus includes a high-pressure fluid supply device 8, a calculation device 4 for calculating polishing roughness, and a steel plate polishing control device 6.

Assuming that the warp correction pass by the present apparatus is the i-th pass, in the (i-1) th pass before the pass, the steel sheet 1 is rolled in the direction indicated by the arrow by the first stand 2-1 of the rolling mill. Is done. Plate warpage detecting device 3 on the exit side of the first stand
, The amount of warpage is detected and input to the arithmetic unit 4.

The arithmetic unit 4 outputs the output signal of the sheet warpage detecting unit 3 and the rolling conditions (sheet thickness,
The function f is calculated based on the rolling reduction and the roll diameter) to determine the surface of the steel sheet to be ground to correct the plate warpage, and the warpage is determined by rolling in the i-th pass which is a warp correction pass. The roughness required for straightening is determined, and appropriate conditions for imparting the roughness, that is, the pressure of the high-pressure fluid and / or the injection amount of abrasive grains are calculated, and the value is output to the steel plate surface polishing apparatus 6. .

The steel plate polishing control device 6 outputs a control command to the abrasive supply device 7 and the high-pressure fluid supply device 8 based on the value from the arithmetic device 4.

In this way, an appropriate amount of abrasive grains is sprayed together with the high-pressure fluid onto the surface of the steel sheet from the abrasive grain spray nozzle 9a or 9b.

The roughness given to the surface of the steel sheet required to correct the warpage detected by the sheet warpage detecting device is determined in advance by an experiment, and input to an arithmetic unit. Keep it.

The sheet warpage detecting device 3 is preferably an apparatus which measures the distance to the material to be rolled by, for example, a laser beam and detects the sheet warpage as a change in the measured value.

FIG. 2 is a longitudinal sectional view showing an example of the abrasive jet nozzle. The abrasive spray nozzle 9 shown in FIG. 1 includes a high-pressure fluid spray nozzle 15 that sprays a high-pressure fluid introduced from a high-pressure fluid passage pipe 11 attached to a nozzle holder 10. Injection nozzle 12
The abrasive grains introduced into the abrasive grain introduction pipe 13 communicating with the nozzle are mixed at the portion of the abrasive grain ejection nozzle 12 and ejected by the high-pressure fluid. In order to grind the upper and lower surfaces of the steel plate in the entire width in the width direction, the abrasive spray nozzles 9 are arranged on one side or both sides of the rolling mill as many as can be ground in the width direction.

Since the width of the steel plate to be rolled changes, a large number of abrasive spray nozzles are arranged in the width direction of the steel plate so as to correspond to the width, and the number of nozzles to be used may be determined according to the width of the steel plate.

Although there is no particular limitation on the abrasive grains,
Iron sand is preferred. In addition, high-pressure water or pressurized air is used as the high-pressure flow medium, and the pressure is 500 to 700 kgf.
/ Cm ² is preferred.

FIG. 3 is a diagram showing an example of an abrasive supply device. The abrasive supply device may be a commonly used one.

The abrasive grain supply device shown in FIG. 3 comprises an abrasive grain cutting hopper 15 and a multi-blaster 17, and the abrasive grain cutting hopper 15 has a cutting amount adjusting valve 17 at its lower part.
The opening of the valve is adjusted by a command from the steel plate polishing control device.

In this apparatus, abrasive grains dried by a dryer (not shown), for example, iron sand, are supplied to the cutting hopper 15, and a predetermined amount of iron sand is supplied to the multi-blaster 17 from the cutout. The iron sand is agitated in the multi-blaster 17 by the air supplied from the compressed air supply passage 19, discharged from the transport passage 18 together with the compressed air, and supplied to the abrasive jet nozzle. Although the above description has been given of the case where the present invention is applied to rolling in a rubber mill, the present invention can also be applied to tandem rolling used for hot rolling finish rolling. Further, in the case of the above-mentioned reversing mill, it is also possible to provide the device of the present invention on both sides of the rolling mill 2 and to correct the warp that could not be corrected in the warp correction pass in the subsequent pass.

[0030]

Example: thickness 200 mm, width 2000 mm, length 25
A 00 mm carbon steel slab was heated to 1150 ° C.
The 17-pass reversal rolling was carried out using the apparatus shown in FIG. Table 1 shows the rolling conditions.

[0031]

[Table 1]

In the rolling, the 17th pass was defined as a warpage correction pass, and the warpage was corrected by the apparatus of the present invention. The rolling conditions of the 16th pass and the 17th pass were as follows.

16th pass rolling reduction: 28% Rolling temperature: 810 ° C Rolling speed: 100 rpm 17th pass rolling reduction: 26% Rolling temperature: 800 ° C Rolling speed: 100 rpm The slab in the 16th pass is warped to the upper surface by 25 mm at the tip. Was.
Since f in the 17th pass, which is the processing correction pass, was 2.5, after rolling, iron sand was projected from the nozzle on the lower surface of the steel sheet under the following conditions, and rolling was performed in the 17th pass.

Projection conditions Supply of iron sand: 10 kgf / min Pressure of high pressure water: 650 kgf / cm ² After rolling of the 17th pass was completed, the amount of warpage at the tip of the slab was measured to be 3 mm.

The warpage indicates the height of the slab tip from the flat plate surface after the slab after rolling is placed on a flat plate.

[0036]

According to the apparatus of the present invention, not only the sheet warpage can be effectively eliminated by on-line control, but also the steel sheet polishing means employs an abrasive grain injection method using a pressure medium, so that the steel sheet surface roughness can be online. The degree can be adjusted accurately and precisely, and the warpage of the plate can be stably controlled without the conventional belt breakage and roll wear due to polishing. Therefore, there is almost no occurrence of rolling interruption and unrolled products due to the warpage of the sheet, and there is a great effect that the quality and productivity of the steel sheet can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus of the present invention.

FIG. 2 is a view showing a vertical cross-sectional view of an abrasive jet nozzle.

FIG. 3 is a diagram illustrating an example of an abrasive supply device.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Steel plate 2-1 and 2-2 Rolling mill 3 Sheet warpage detector 9a, 9b Abrasive grain injection nozzle 10 Nozzle holder 15 High pressure fluid injection nozzle 12 Abrasive grain injection nozzle 11 High pressure fluid introduction pipe

Claims (1)

[Claims] 1. A sheet warpage detecting device installed on an outlet side of a hot rolling mill, and a polishing abrasive jet for polishing capable of grinding the entire width direction of upper and lower surfaces of a steel sheet provided on an inlet side of the hot rolling mill. A nozzle, an abrasive supply device and a high-pressure fluid supply device for supplying abrasive grains and a high-pressure fluid to the nozzle, and a polishing rough surface of a steel plate surface necessary for correcting the plate warpage detected by the plate warpage detection device. And a polishing control device for determining the abrasive supply amount and the pressure of the high-pressure fluid based on the calculation result, and controlling the abrasive supply device and the high-pressure fluid supply device. A board warpage control device, characterized in that: