JP2002126805A - Method for rolling and cutting endless hot rolled steel strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a subsidiary fracture failure of a splicing portion caused by an excessive tensile force when an edge of hot rolled steel strip is wound into a coiler mandrel in an endless hot rolling. SOLUTION: A splicing point is transferred with a trucking device 30 and a cutting target point is decided so as to be situated at the upstream side than the splicing point and the splicing point is always placed safely at the revolute position of a preceding stock even if fluctuations in the cutting work may occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling and cutting an endless hot-rolled steel strip.

[0002]

2. Description of the Related Art Raw materials (slabs) having the same or different dimensions and steel types are joined on a hot strip mill line during or after rough rolling, and finished to predetermined dimensions by endless finish rolling. Subsequently, continuous hot rolling (endless rolling) has been proposed in which the product is cut into a length according to the order, wound up, and processed into a product coil.

[0003] Fig. 8 shows a typical equipment arrangement row of such a continuous hot rolling mill. The raw material rolled by the rough rolling mill 1 is joined by a sheet bar joining device 2 via a crop shear 3, rolled to a predetermined thickness by a finishing mill 4, cooled by a hot-rolled steel strip cooling device 6, and stripped by a strip shear 7. The product is cut into coil units and passed through a coiler pinch roll 8 to a coiler 9.
It is wound up.

FIG. 2 shows the concept of each step of such endless hot rolling. The raw materials produced in the casting 21 process for each steel type and size are joined in the joining 24 process through the heating 22 and the rough rolling 23, and are endlessly rolled in the continuous finishing hot rolling 25 process. In FIG. 2, during the process from joining 24 to cutting 26, sheet bars of the same steel type or different steel types and different dimensions are connected and endless hot-rolled. After cutting, the product is divided according to the order, and is wound around a coil in a winding step 27.

[0005] In this series of steps, in the cutting and winding operations of the endless hot-rolled steel strip after finish rolling, for example, thin sheets having different dimensions such as different steel types, different thicknesses, and sheet widths are continuously rolled. It is required to cut what has been done at the changed part of the steel type and the changed part of the dimensions without reducing the yield as much as possible, and to wind the product coil into a single steel type and single size product coil .

In general, the yield is improved by cutting with a strip shear at a point where different sheet bars are connected.

[0007]

According to the above-described method of cutting at a joining point as a target, when cutting an endless hot-rolled steel strip moving at an extremely high speed, an error in the cutting position becomes large. Due to the error in the cutting position, the joining point is located on the outer winding side of the preceding material (the front material at the time of cutting) or the inner winding side of the succeeding material (the rear material at the time of cutting).

(2) When the tip of the succeeding material is wound around the mandrel of the coiler, a large instantaneous tension is generated between the mandrel and the pinch roll before the shear. If the material strength of the joint is weaker than the instantaneous tension, there is a problem that the endless hot-rolled steel strip may be broken at the weakest point.

In the case (2) above, the material involved in the accident cannot be produced as a matter of course and is treated as scrap. In addition, the line has to be shut down for a long time to recover from the accident. This means that the purpose of endless hot rolling with the aim of improving efficiency cannot be achieved.

With respect to the problem (1), the above problem does not occur when the junction is located on the outer winding side, but when the junction is too far ahead of the coil cut portion, Since the outer winding portion is scrapped, there is a problem that the coil yield is reduced.

As means for solving such a problem, techniques disclosed in Japanese Patent Application Laid-Open Nos. 61-14007 and 4-28416 are disclosed. In these techniques, cutting is performed aiming at a joining point. Therefore, when a cutting position error accompanying high-speed rolling becomes large, the above problem cannot be avoided.

Japanese Patent Application Laid-Open No. 61-14007 discloses a method of cutting and removing a portion including a rolled material connecting portion by using two pairs of high-speed cutting machines operating synchronously.
Application to a strip moving at high speed is mechanically unreasonable and difficult to realize.

An object of the present invention is to provide a technique for cutting a hot-rolled steel strip which solves the above-mentioned problems.

That is, a first object of the present invention is to provide a method of cutting an endless rolled material which does not break at a joint when winding a coil in endless rolling of an endless rolled steel strip. An object of the present invention is to provide a method of cutting an endless rolled steel strip capable of producing a hot coil in which an excessively truncated portion is reduced as much as possible.

[0015]

SUMMARY OF THE INVENTION According to the present invention, an endless hot-rolled steel strip is obtained by joining sheet bars before finish rolling, and continuously finish-rolling the obtained joined sheet bar. In a continuous hot rolling process in which the band is cut just before winding and wound into a coil, a joining point is generated in the tracking device, and after the joining point has passed through the finishing stand, a cutting target point is generated. A method of rolling and cutting an endless hot-rolled steel strip, characterized in that the coil is cut so as to be positioned at an outer winding of a coil.

[0016]

The present invention will be specifically described below.

FIG. 1 is a block diagram of an apparatus for tracking a joining point, determining a cutting point, and cutting a predetermined position of a continuously rolled endless hot-rolled steel strip.

In FIG. 1, 1 is a rough rolling mill, 2 is a sheet bar joining device, 2a is a plate speed detecting device, 3 is a crop shear, 4 is a finish rolling mill, 5 is a pinch roll before shear, 7
Denotes a strip shear, 8 denotes a coiler pinch roll, 9 denotes a coiler, and 1a denotes a coil box.

The raw material roughly rolled by the rough rolling mill 1 is once wound into a coil box 1a and unwound for the next finish rolling. The leading end of the succeeding rolled material unwound from the coil box 1a is joined to the tail end of the preceding rolled material by the sheet bar joining device 2.

The joint information at this time is stored in the tracking device 3.
0, and thereafter, on a computer, a joint point is generated on the tracking device 30, and the plate speed detecting device 2a
It is transferred to downstream equipment based on the detected value of the (measurement roll) and passes through the first stand of the finishing mill 4. The position of the joining point in the finishing mill 4 is obtained by successive calculation using the exit side plate thickness of each stand and each stand speed.

After the joint point tracked in the computer has passed through the final finishing stand, when the steel sheet having the length specified by the host computer 40 is sent out from the finishing mill 4, the tracking device 30 starts the finishing rolling. A cutting target point is generated at the position of the last stand of the machine 4.

The target cutting point is transferred on the transport table by calculation using the actual value of the roll peripheral speed of the final stand of the finishing mill 4. 1. In transport table
The conveying speed of a 0 mm thick steel plate is about 1000 mpm.
The strip is cut by the strip shear 7 aiming at the cutting target point.

The determination of the cutting target point is performed as follows.

As described above, since the position of the joint is transferred by calculation on the tracking device 30, there is a difference between the position on the computer, that is, on the tracking device 30, and the actual position of the joint. Therefore, when determining the cutting target point for the joining point on the tracking device 30, it is necessary to consider an error between the position of the joining point and the actual position.

Further, even after the generation of the cutting target point, an error of tracking up to the strip shear 7 occurs.
This is because, even when the cutting target point is transferred on the transport table, the transfer is performed on the tracking device 30, that is, on the controller.

Further, in the present invention, the junction may be recognized by a detector arranged immediately upstream of the strip shear, and the position on the upstream side of the recognized junction may be determined as the target cutting point. .

The method of detecting the cutting point and the method of cutting in this case will be described below.

At the joint portion at the sheet bar stage, the tail end of the preceding material 10 advancing in the advancing direction 12 and the leading end of the succeeding material 11 are formed with corner cuts 10a, 11a as shown in FIG. Generally, when the central straight portion 13 is joined by a joining machine, a notch mark 15 as shown in FIG. 5 is provided. FIG. 6 shows an example in which a planar shape detector 14 is arranged on the upstream side of the strip shear 7. The changed shape of the flat shape of the width of the hot-rolled steel sheet clearly remains even after finish rolling, and can be easily detected by the flat shape detector 14 or a general width meter, and accurately joined. The part can be grasped. Therefore, it is possible to cut at a desired position by giving this information to the strip shear and adjusting the cutting timing.

Further, in the present invention, the cutting target point is determined by comprehensively considering the cutting speed, the tracking error of the joining point, and the cutting control error. As a result, even under the occurrence of the error, the cutting is always performed on the upstream side of the joining point, and the joining point can be stably attached to the outer winding of the preceding material.

The error of the cutting point and how to determine the cutting target point will be described below.

When the cutting point is determined on the basis of the joining point, the cutting point error σ _C is the joining point tracking error σ _TRK
And a shear control error σ _SH .

The relationship between the magnitudes of the respective errors (represented by the standard deviation) is as follows: σ _C = √ (σ _TRK ² + σ _SH ² ) (1) Although σ _TRK and σ _SH change depending on the cutting speed, it is easy to estimate the relationship between the cutting speed and these errors.

The cutting target point may be set upstream of the tracked joining point by a distance of α * σ _C.
Here, α is an adjustment constant.

Since errors generally appear in a normal distribution, α = 3 may be set to ensure that the cutting position is located on the upstream side of the joining point. The strip (steel plate) is cut by the strip shear to aim at the cutting target point thus determined. The steps are as described below.

The strip shear 7 has a cutting control device 5
0 is provided and shear speed control and cutting control are performed as described above. The strip shear 7 is a rotary shear having cutting blades on the upper and lower rotating drums. Here, the cutting target point is set at a position where the cutting blades face each other, and at the same time, the speed of the hot-rolled steel strip and the peripheral speed of the rotating drum match. The rotation speed is controlled in such a manner.

The cutting target point is located at a predetermined distance from the strip shear 7 (about 2 mm when the conveying speed of the steel sheet is about 1000 mpm).
0m), the distance between the upper and lower drums is reduced, and the upper and lower cutting blades are overlapped and cut.

As described above, the method of determining a cutting position by tracking the bonding points generated in the bonding apparatus on a computer has been described. However, the method of determining the cutting position is not limited to this.

For example, as shown in FIG. 3, a joint point detecting sensor 60 is provided on a transfer table on the exit side of the finishing mill 4, and thereafter, the detected joint points are tracked on a computer to determine a cutting point. Can also be performed.

In this case, the joining point can be easily detected by the notch 15 generated at the time of joining.

In the present invention described above, if the cutting target point is α × σ _C and α = 3 from the junction, the junction can be reliably positioned on the outer winding side, and The dissimilar steel type part existing in the outer winding part can be statistically minimized.

[0041]

EXAMPLE 1 FIG. 1 shows a block diagram of an apparatus for cutting an endless hot-rolled steel strip.

When the joining information is input from the sheet bar joining device 2 to the joining completion 31 of the tracking device 30, the occurrence of the joining point 32 is confirmed, and the joining point is determined based on the detection value of the plate speed detecting device 2a (measuring roll). The transfer 33 is calculated. When the joining point passes through the first stand 34 of the finishing mill 4, the exit thickness of each stand of the endless rolled steel strip on the exit side of each stand of the finishing mill 4 and the speed information 35 of each stand are input. Based on this, a sequential calculation is performed, and a timing 36 at which the joining point passes through the final stand of the finishing mill 4 is calculated.

The tracked joining point is the finishing mill 4
After passing through the final stand, when the steel sheet of the length indicated by the signal from the cutting point setting 41 of the host computer 40 is sent out from the final stand of the finishing mill 4, the tracking device 30 A cutting target point is generated at the position of the last stand of the mill 4 and the final stand passing timing 37 of the finishing mill 4 at the cutting point (cutting target point) is set. The information of the last stand passage 37 at the cutting point is output to the cutting control device 50, which inputs the information to the shear speed synchronization control 51, and performs control calculation of the shear speed.

On the other hand, the tracking device 30 calculates a cutting point transfer 38 until the cutting point reaches the strip shear 7,
The result is output to the cutting control device 50. The cutting control device 50 performs the cutting control 5 of the strip shear 7 on the basis of the two pieces of information of the cutting point transfer 38 and the shear speed synchronization control 51.
Execute Step 2. Embodiment 2 FIG. 3 is a block diagram showing another embodiment. Instead of the tracking of the first embodiment, the tracking device 30 inputs a signal of a joint point detection sensor 60 provided at a position after leaving the final stand of the finishing mill 4 and performs a joint point detection 61. In response to a signal from the cutting point setting 41 of the host computer 40, the tracking device 30 executes the cutting point generation 62 at a position closer to the finishing mill 4 than the joint point detection sensor 60. The information of the cutting point occurrence 62 is input to the shear speed synchronization control 51 of the cutting control device 50.

On the other hand, the tracking device 30 calculates the transfer 64 of the cutting point until the cutting point reaches the strip shear 7, and inputs this to the cutting control device 50. The cutting control device 50 controls the cutting of the strip shear 7 based on these two pieces of information.

In the present invention, as described above, the cutting target point is determined by comprehensively considering the cutting speed, the tracking error of the joining point, and the cutting control error. In any of Example-2, the cutting is always performed on the upstream side of the joining point. Therefore, the joining point can be stably attached to the outer winding of the preceding material. Embodiment 3 An embodiment will be described with reference to FIGS.

For example, the cutting speed of the hot-rolled steel strip in the range of the product sheet thickness of 0.8 to 6.0 mm is 300 to 1200 mpm. In addition, in order to prevent the tracking accuracy of the cutting point from deteriorating, no acceleration / deceleration is performed during the tracking of the cutting point.

FIG. 7 is an explanatory diagram showing an embodiment of the present invention. The hot-rolled steel strip 10 finish-rolled by the finish-rolling machine 4 is wound on a coiler 9 via a pinch roll 8. The target cutting point B is set upstream of the joining point A with respect to the tracked joining point A. The joining point A is determined by tracking the joining position from the entry side of the finishing mill 4. That is, after the joining point A has passed through the final stand of the finishing mill 4, the transfer length is calculated based on the exit side sheet speed of the finishing mill 4 and the elapsed time, and the joining point A is obtained.

In the embodiment in which the distance from the final stand of the finishing mill 4 to the strip shear 7 is about 150 m, the error in cutting the hot-rolled steel strip 10 having a thickness of 1.0 mm at a speed of 1000 mpm is a tracking error σ. _TRK
Was 2.51 m, the cutting control error σ _SH was 0.33 m, and the cutting point error σ _C was 2.53 m. When the tracking error σ _TRK and the cutting control error σ _SH are expressed in time, they correspond to 150 msec and 20 msec, respectively. Cutting the target point correction amount L _C is determined by the following equation.

L _C = α * σ _C Here, α ≒ 3 is set for safety, and the cutting target point B is set upstream of the tracked junction point A by about 8 m.

In the above-described embodiment, the method of cutting a hot-rolled steel strip having a thickness of 1.0 mm has been described, but good results can be obtained by applying the same method to any sheet thickness. . Further, the method of tracking the junction A is not limited to this embodiment, and various conventionally known tracking methods can be applied.

[0052]

According to the present invention, since the joining point of continuous hot rolling is stably positioned at the outer winding of the product coil, excessive tension when the tip of the hot-rolled steel strip is wound around the coiler mandrel. There was no breakage of the joints due to the above, and the facility operation rate and yield were greatly improved. Further, since the joining portion is always attached to the outer winding of the hot coil, the unnecessary portion can be surely removed at the entrance of the next step.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a divided state of a slab and a coil in each step.

FIG. 3 is a block diagram of an embodiment of the present invention.

FIG. 4 is a plan view of a joint portion of a sheet bar before joining.

FIG. 5 is a plan view of a joint portion of the sheet bar at the time of joining.

FIG. 6 is an explanatory view in which a planar shape detector is installed on the upstream side of a strip shear.

FIG. 7 is an explanatory diagram of the embodiment.

FIG. 8 is a layout diagram of endless hot rolling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rough rolling mill 1a Coil box 2 Sheet bar joining device 3 Crop shear 4 Finish rolling mill 5 Pinch roll before shearing 6 Hot rolled steel strip cooling device 7 Strip shear 8 Koila pinch roll 9 Coirer 10 Leading material 11 Trailing material 12 Progression direction DESCRIPTION OF SYMBOLS 13 Straight part 14 Plane shape detector 15 Notch 21 Casting 22 Heating 23 Rough rolling 24 Joining 25 Finish rolling 26 Cutting 27 Winding 30 Tracking device 31 Joining completed 32 Joining point generation 33 Joining point transfer 34 Joint stand first finishing stand Passing 35 Thickness and speed at the exit side of each stand 36 Passing the final stand at the joining point finish 37 Passing the final stand at the cutting point 38 Transferring the cutting point 40 Host computer 41 Cutting point setting 50 Cutting control device 51 Shear speed synchronization control 52 Cutting control 60 Detection sensor 61 Joint point detection 62 Cutting point generation 63 Above the final stand speed 64 cutting point transfer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Imazeki 1 Kawasaki-cho, Chuo-ku, Chiba Kawasaki Steel Co., Ltd. (72) Inventor Toshisada Takechi 1 Kawasaki-cho, Chuo-ku, Chiba Kawasaki Steel Co., Ltd. F-term in the steelworks (reference) 4E002 AD04 BD03 BD05 BD06 CB05 CB10 4E026 BA04 BA13

Claims (1)

[Claims] 1. A sheet bar is joined before finish rolling, and the obtained joined sheet bar is continuously finish-rolled to obtain an endless hot-rolled steel strip, and the endless hot-rolled steel strip is cut just before winding. In the continuous hot rolling step of winding on a coil, a joining point is generated in the tracking device, and after the joining point passes through the finishing stand, a cutting target point is generated, so that the joining point is located on the outer winding of the coil. A method of rolling and cutting an endless hot-rolled steel strip, comprising cutting into a shape.