JP2001321820A - Method and device for hot-rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for hot-rolling for preventing the damage of a heating device and also improving the heating efficiency of a rough bar. SOLUTION: In the prior method, a billet is made into the rough bar 4 by rolling it with a roughing mill 1 and, after continuously heating the obtained rough bar using a heating device 3, the resultant rough bar is hot-rolled into a steel strip with a finishing mill 2. In this method and device, the deviation of the center axis in each position in the longitudinal direction of the rough bar relative to the center axis of a rolling line is detected on the upstream side of the heating device 3 and the rough bar is heated in accordance with the deviation as moving the heating device 3 in the width direction of the rough bar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolling apparatus in which a rough bar heating device is disposed between a rough rolling mill and a finishing rolling mill. TECHNICAL FIELD The present invention relates to a hot rolling method and a hot rolling apparatus for improving the heating efficiency of steel.

[0002]

2. Description of the Related Art A slab (a so-called slab having a rectangular cross-sectional shape) is heated in a heating furnace, rolled by a rough rolling mill, and then rolled by a finishing mill to produce a hot-rolled steel strip. In the hot rolling method, a slab in a heating furnace is usually conveyed using a walking beam. At that time, the temperature of the portion of the slab that comes into contact with the walking beam is lower than that of the other slabs, and so-called skid marks are formed.

Since the skid marks have high hot deformation resistance, the thickness and width of the finish-rolled hot-rolled steel strip are likely to fluctuate. Therefore, conventionally, a heating device for heating the coarse bar is arranged between the rough rolling mill and the finishing rolling mill, and the temperature of the skid mark and the coarse bar in the other part is made uniform, so that the finishing rolling mill is used. The rolling accuracy of the hot-rolled steel strip is suppressed, and the variation in the thickness and width of the hot-rolled steel strip is suppressed. At that time, an induction heating method is mainly adopted as a coarse bar heating device in order to increase the temperature rise speed of the coarse bar.

By the way, a rough bar rolled by a rough rolling mill may have a shape defect such as warpage or camber. At this time, when the rough bar comes into contact with the heating device, flaws are generated on the surface of the rough bar, so that flaws are easily generated on the surface of the hot-rolled steel strip. When the degree of the warpage or camber is extremely large, the coarse bar collides with the heating device and damages the heating device.

Therefore, Japanese Patent Application Laid-Open No. 9-314201 proposes a method in which a warp detector and a flatness correction device are provided upstream of a heating device for a coarse bar. This method
This is a method of correcting the detected warpage at the front end and the rear end of the rough bar, that is, the vertical fluctuation of the rough bar using a flatness correcting device. With this method, it is possible to effectively cope with warpage of the rough bar.

On the other hand, Japanese Patent Laying-Open No. 10-328708 proposes a method in which side guides are arranged on the entrance and exit sides of a heating device for a coarse bar. This method can handle rough bars with camber at the front or rear end,
Alternatively, this is a method for coping with the meandering of the coarse bar.

However, in this method, it is difficult to integrate the side guide and the heating device for the coarse bar into an integral structure. Therefore, especially when a large camber is generated at the distal end of the coarse bar, Enter the gap between the side guide and the heating device, and the heating device is easily damaged. The reason why the side guide and the heating device cannot be formed into an integral structure is that the heating device usually needs to have a structure capable of retracting outside the rolling line for equipment maintenance. Even if the heating device is not damaged, the rough bar comes into contact with the side guide or the heating device, and a flaw is generated on the surface of the rough bar, and the flaw is likely to remain on the hot-rolled steel strip.

By the way, if the width of the heating device is made extremely large with respect to the width of the coarse bar in order to avoid contact or collision between the coarse bar and the heating device, the heating efficiency will deteriorate. In particular,
When the heating device is of the induction heating type, if the distance between the coarse bar and the induction coil is large, the heating efficiency is greatly reduced.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a hot rolling apparatus in which a heating device for a coarse bar is disposed between a rough rolling mill and a finishing rolling mill. An object of the present invention is to provide a hot rolling method and a hot rolling device that improve the heating efficiency of a rough bar.

[0010]

The gist of the present invention resides in a hot rolling method shown in the following (1) and a hot rolling device shown in the following (2). (1) A method in which a slab is rolled by a rough rolling mill to form a rough bar, and the obtained rough bar is continuously heated using a heating device, and then hot rolled into a steel strip by a finishing rolling machine. On the upstream side of the heating device, the shift of the center axis of each position of the coarse bar in the longitudinal direction with respect to the center axis of the rolling line is detected, and in response to the shift, the heating device is moved in the width direction of the rough bar, Hot rolling method for heating coarse bars. (2) A hot rolling device having the following features:

[0011] A heating device for heating the coarse bar is disposed between the rough rolling mill and the finish rolling mill.

An upstream side of the heating device is provided with a coarse bar position detecting device for detecting a shift of the central axis of each coarse bar in the longitudinal direction with respect to the central axis of the rolling line.

On the upstream side of the heating device, there is further provided a rough bar position calculation for calculating a shift of a central axis for each longitudinal position of the rough bar based on a signal inputted from the rough bar position detecting device. Have a vessel.

The heating device is provided with a heating device position controller for calculating a movement timing and a movement amount for moving the heating device in the coarse bar width direction based on the coarse bar position signal from the coarse bar position calculator. That

[0015] The heating device may further include a heating device moving device that moves the heating device in the width direction of the coarse bar based on a control signal from the heating device position controller.

The "deviation" of the center axis of each coarse bar relative to the center axis of the rolling line in the longitudinal direction will be described.

FIG. 1 is a diagram schematically showing the deviation of the center axis of a rough bar rolled by a rough rolling mill. FIG. 1A is a diagram illustrating the state of the leading end of the rough bar, and FIG. 1B is a diagram illustrating the state of the rear end of the rough bar. The arrow shown in the figure indicates the direction in which the coarse bar is conveyed.

In a normal hot-rolled steel strip rolling mill, the rough bar 4 is rolled while being controlled such that the central axis Tb in the longitudinal direction thereof coincides with the central axis Tc of the rolling line. However, as shown in FIG. 1A, a camber may be generated at the tip of the coarse bar. The camber at the tip of the coarse bar is a state in which the tip of the coarse bar touches the center axis of the rolling line in the traveling direction horizontally and vertically (up and down on the paper). The symbol A in the figure is the camber amount at the tip of the coarse bar. Similarly, the symbol B shown in FIG. 1B is the camber amount at the rear end of the coarse bar. In addition, the meandering of the coarse bar is usually small, but the meandering may increase due to a malfunction of the operation or a trouble in equipment.

FIG. 2 is a diagram showing an example of an apparatus configuration for implementing the method and apparatus of the present invention. In the figure, reference numeral 1 denotes a rough rolling mill, reference numeral 2 denotes a finish rolling mill, and reference numeral 10 denotes a table roller. On the upstream side of the heating device 3 for the rough bar 4, a rough bar position detecting device 5 and a rough bar position calculator (FIG. 2)
(Not shown).

In this coarse bar position calculator, the camber amount at the front end and the rear end of the coarse bar or the meandering amount of the coarse bar is determined based on the signal from the coarse bar position detector 5 in the longitudinal direction of the coarse bar. Calculate in accordance with. The signal of the calculation result is input to a heating device position controller (not shown in FIG. 2) described later.

In the heating device position controller, the coarse bar 4 is prevented from contacting the heating device 3 based on a control signal from the coarse bar position calculator, and the distance between the coarse bar and the heating device is further reduced. The control signal is input to the moving device 7 of the heating device so that the heating device 3 becomes appropriate, and the heating device 3 is moved in the coarse bar width direction.

The method and apparatus of the present invention described above can prevent the coarse bar from contacting or colliding with the heating device, and properly adjust the relative positional relationship between the coarse bar and the heating device. Therefore, it is possible to prevent the heating device for the coarse bar from being damaged, and to improve the heating efficiency of the coarse bar. Further, it is possible to obtain a hot-rolled steel strip of good quality with no flaws on the surface.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A hot rolling method and a hot rolling apparatus according to the present invention will be described below. FIG. 3 is a block diagram showing a control system in the method and apparatus of the present invention. Reference numeral 9 in the figure denotes a coarse bar position sensor described later, and reference numeral 10 denotes a table roller. A position signal relating to the camber or meandering of the coarse bar 4 from the coarse bar position detector 5 is input to the coarse bar position calculator 6. In this coarse bar position calculator, the camber amount or the meandering amount at the front end and the rear end of the coarse bar is calculated corresponding to the longitudinal position of the coarse bar obtained from a longitudinal position detector (not shown). , And inputs the signal of the calculation result to the heating device position controller 8. In the heating device position controller 8,
The movement timing of the heating device in the coarse bar width direction for each position of the coarse bar in the longitudinal direction and the movement amount at that time are calculated, and a control signal as the calculation result is output to the moving device 7 of the heating device. The moving device 7 moves the heating device 3 in the coarse bar width direction based on the input control signal.

The heating device 3 is preferably of a commonly used induction heating type. This is because the temperature of the coarse bar can be quickly increased.

The coarse bar position detecting device 5 includes, for example, a width meter of a lower light source type which is usually used for measuring the width of a plate, a width meter for calculating a plate width and a width center by a self-luminous type width meter, or a camber. Meter can be used. As the camber meter, a method in which a plurality of commonly used width gauges are arranged in the transport direction can be used.

FIG. 4 is a diagram schematically showing an example of a situation in which a camber generated at the tip of a coarse bar is avoided using the method and apparatus of the present invention. FIG. 4 (a), FIG. 4 (b)
FIG. 4C shows a situation in which the positional relationship between the coarse bar and the heating device changes over time. Reference numeral 7 in the figure denotes a moving device of the heating device, and reference numeral 11 denotes a rail of the moving device.

In FIG. 4A, a camber is generated at the tip of the coarse bar 4, and the tip is bent upward (hereinafter, referred to as WS side in the work side of the heating device) on the paper. And a state where such a coarse bar is approaching the heating device. In this case, there is a great risk that the WS side of the heating device collides with the tip of the coarse bar. Arrows shown in FIG. 4A indicate the conveying direction of the coarse bar.

In FIG. 4B, immediately before the coarse bar enters the heating device, the heating device moves to the WS side according to the camber amount at the tip of the coarse bar, and the coarse bar does not collide with the heating device. ,
This shows a state where the wafer is carried into the heating device. The arrow shown in FIG. 4B indicates the moving direction of the heating device.

FIG. 4C shows a state after the camber generating portion at the tip of the coarse bar exits the heating device and the position of the coarse bar in the width direction returns to normal. The arrow shown in FIG. 4C indicates the moving direction of the heating device.

When the above-described lower light source type or self-luminous width meter is used as the coarse bar position detecting device, it is desirable to dispose these width meters immediately near the entrance of the heating device.
This is for detecting the position of the coarse bar entering the heating device with higher accuracy.

When a camber meter is used as the coarse bar position detecting device, it is desirable to arrange a coarse bar position sensor immediately before the heating device to track the position of the coarse bar. Reference numeral 9 in FIG. 3 indicates the position sensor of the coarse bar. The reason why it is better to dispose the coarse bar position sensor immediately before the heating device is that it is necessary to install the camber meter at a position at a certain distance from the heating device. That is, when measuring the camber amount of the coarse bar with the camber meter, the distance between the camber meter and the heating device is set to 10 because the camber amount at the front end or the rear end in a fixed coarse bar length is measured. It is necessary to secure about 30 m. Therefore, the position information of the coarse bar detected by the camber meter may slightly deviate from the position of the coarse bar entering the actual heating device. Therefore, it is desirable to measure the timing when the coarse bar enters the heating device and the longitudinal position after the coarse bar enters the heating device before the heating device. A measuring roll, a laser Doppler velocimeter, or the like can be used as the coarse bar position sensor.

The present technology is also effective for a heating device which can heat both ends of the coarse bar in the width direction separately.

FIG. 5 is a view schematically showing a situation in which a camber generated at the tip of the coarse bar is avoided by using the heating device divided into both ends in the width direction of the coarse bar of the present invention. is there. As shown by an arrow in the figure, the situation where the positional relationship between the coarse bar and the heating device changes with the passage of time (the diagram on the left side shows the state after the passage of time). Since the positions of the heating devices on both sides can be controlled independently, FIG.
The heating efficiency is further improved as compared with the case where the entire width direction of the rough bar is heated by an integrated heating device.

When the detected camber amount or meandering amount is larger than a predetermined amount, it is desirable to temporarily retreat the heating device out of the rolling line. In order to secure the heating efficiency of the heating device, it is good to restrict the width of the heating device with respect to the width of the coarse bar, so if the camber amount or the meandering amount is larger than a predetermined amount, do not retract the heating device. Then, the coarse bar easily contacts the heating device.

[0035]

By applying the method and apparatus of the present invention,
In a hot rolling apparatus in which a heating device for a coarse bar is arranged between a rough rolling mill and a finishing rolling mill, damage to the heating device can be prevented and the heating efficiency of the rough bar can be improved. Further, it is possible to obtain a hot-rolled steel strip of good quality with no flaws on the surface.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a deviation of a center axis of a rough bar rolled by a rough rolling mill.

FIG. 2 is a diagram showing an example of an apparatus configuration when implementing the method and apparatus of the present invention.

FIG. 3 is a block diagram showing a control system in the method and apparatus of the present invention.

FIG. 4 is a diagram schematically illustrating an example of a situation in which a camber generated at the tip of a coarse bar is avoided using the method and the apparatus of the present invention.

FIG. 5 is a view schematically showing a situation of an example of avoiding a camber generated at a tip of a coarse bar by using a heating device divided into both ends in a width direction of the coarse bar of the present invention.

[Explanation of symbols]

1: Coarse rolling mill 2: Finish rolling mill 3: Heating device 4: Coarse bar 5: Coarse bar position detecting device 6: Coarse bar position calculator 7: Moving device of heating device 8: Heating device position controller 9: Coarse bar Position sensor 10: Table roller 11: Rail of moving device Tb: Central axis in the longitudinal direction of coarse bar Tc: Central axis of rolling line A: Camber amount at the tip of coarse bar B: Camber amount at the rear end of coarse bar

Claims (2)

[Claims] 1. A slab is rolled by a rough rolling mill to form a rough bar, and the obtained rough bar is continuously heated using a heating device.
In a method of hot rolling to a steel strip by a finishing mill,
On the upstream side of the heating device, the shift of the center axis of each position of the coarse bar in the longitudinal direction with respect to the center axis of the rolling line is detected, and in response to the shift, the heating device is moved in the width direction of the rough bar, A hot rolling method characterized by heating a coarse bar. 2. A heating device for heating a coarse bar disposed between a rough rolling mill and a finishing rolling mill, comprising a heating device for heating a coarse bar at a position in the longitudinal direction of the coarse bar with respect to the central axis of the rolling line. A coarse bar position detecting device for detecting a deviation and a coarse bar position calculator for calculating a deviation of a central axis for each longitudinal position of the coarse bar based on a signal input from the coarse bar position detecting device. A heating device position controller for calculating a movement timing and a movement amount for moving the heating device in the coarse bar width direction based on a coarse bar position signal from the coarse bar position calculator; and the heating device. A hot rolling apparatus comprising: a heating device moving device that moves a heating device in a width direction of a coarse bar based on a control signal from a position controller.