JP3331041B2 - Tracking method of slab joint in continuous hot rolling. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel slab in which billets or slabs are butt-joined at their leading and trailing ends and several to several tens of billets are continuously rolled. With regard to the continuous hot rolling of (1), an attempt is made to accurately track the joint portion of the slab from immediately after joining to winding after rolling.

[0002]

2. Description of the Related Art Conventionally, in a hot rolling line for a steel slab, a steel slab to be rolled is heated, rough-rolled, and finish-rolled one by one to finish a hot-rolled sheet having a desired thickness. However, such a rolling method inevitably causes the line to stop due to poor biting of the rolled material in the finish rolling, and also has a significant disadvantage in that the yield is reduced due to a defective front and rear end shape of the rolled material.

[0003] For this reason, a continuous hot rolling method has recently been adopted in which a rear end portion and a front end portion of a steel slab to be rolled are joined prior to finish rolling, and this is continuously supplied to a hot rolling line for rolling. It has been adopted.

[0004] In carrying out the above-mentioned continuous hot rolling, it is necessary to accurately grasp a joint between billets, that is, a position of a joint.

[0005] This is because it is necessary to change the running strip thickness at the transition (joining portion) between the preceding slab and the following slab or to change the running strip thickness at the transition side of the rolling mill. This is because it is necessary to cut the preceding steel slab and the following steel slab at the joint at the entry side of the take-off device. In particular, when winding the plate material after rolling, it is desirable in the process that the joint is outside the coil, and it is necessary to wind the joint including the rear end side of the preceding material. It was necessary to cut at the tip of the following material.

As a method of tracking a billet joint in continuous hot rolling, conventionally, at least two or more holes are formed in the vicinity of a joint of a rolled material along a longitudinal direction, and the position of the hole is tracked ( Tokuhei 4-69004
Japanese Patent Application Laid-Open No. 4-89136), and a method of providing a width difference between the rear end of the preceding material and the front end of the following material and joining and tracking the width difference portion. .

However, in the former method, since a hole is formed in the steel plate, the portion is not formed as a product, and the portion is cut off. Therefore, the yield is reduced, and it is necessary to introduce a new device such as a hole detection device. On the other hand, in the latter method, since tracking is performed based on the information of the width deviation at one point of the joint, a problem that a tracking error due to noise or the like occurs is expected.

[0008] As another tracking method, a paint is applied to a joint in advance, and a position is detected by a change in radiant energy of the portion (Japanese Patent Laid-Open No. 23708/1993).
JP-A No. 4-2) and a method of detecting the position of a joint by detecting a change in emissivity due to a difference in steel type in the vicinity of the joint by combining the thickness and the width of the plate at the joint.
No. 8416) has also been proposed.

[0009]

However, in the method of applying a paint to the joint in advance and detecting the position based on a change in the radiant energy of the portion, it is necessary to newly introduce equipment for applying the paint. Tracking errors are likely to occur due to noise, etc., because tracking is performed based on the apparent temperature deviation at one point of the joint, and position detection errors increase when the width of the paint applied is widened to avoid tracking errors. Furthermore, the position of the paint to be applied, difficulty in increasing the accuracy of the timing, and other disadvantages were also caused by a change in the steel type near the joint, in which the thickness and width of the joint at the joint were changed. In the method of detecting the position based on the emissivity change, it is difficult to detect the position of the joint when materials having almost the same emissivity are joined. There was.

The conventional tracking method has various problems as described above, and furthermore, since the position of the joint is detected by the detection signal at one point of the joint, a tracking error due to noise or the like cannot be avoided. Therefore, the yield was inevitably reduced due to cutting involving a large amount of.

An object of the present invention is to propose a method capable of reducing a tracking error or the like at a joint which cannot be avoided in the past when a preceding steel slab and a subsequent steel slab are joined and continuous hot finish rolling is performed. There.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a method for joining a joined steel slab that has been subjected to butt joining from the entry side of a facility for continuous hot rolling to a cutting machine arranged at the exit side. In the continuous tracking in, the temperature of the joining steel slab is continuously measured at least at one place in the region from the entry side of the continuous hot rolling equipment to the cutting machine arranged on the exit side thereof, By extracting the temperature deviation pattern of the unsteady part including its surroundings, and comparing this temperature deviation pattern with the previously-determined pattern of the temperature deviation of the unsteady part, whether or not it is a billet joint is determined. A method of tracking a slab joint in continuous hot rolling, characterized by determining the following: Yo It is desirable to determine a low-temperature section threshold, and to extract a temperature deviation pattern of an unsteady section based on the threshold and the measured temperature. In order to perform more accurate tracking, Preferably, the threshold value is changed based on a temperature deviation pattern obtained by actual measurement, and a new temperature deviation pattern is created based on the changed threshold value.

FIG. 1 shows an example of equipment suitable for carrying out the present invention. In the figure, 1 is a rough rolling machine, 2 is a rough rolling machine 1
A shearing device for removing crops from the leading end and the trailing end of the billet S on the outgoing side of the slab, 3 is a joining device for butt joining the leading end and the trailing end of the billet, and 4 is a joining device for continuously joining the billet to a predetermined thickness This is a group of finishing mills that rolls to. Also, 5a-5
c is a thermometer for measuring the temperature of the billet S, 6 is a tracking device, and this tracking device 6 is a thermometer 5a to 5a.
Based on the temperature of the slab S measured at 5c, a pattern of the temperature deviation of the unsteady portion of the slab (hereinafter, simply referred to as a temperature pattern) is extracted, and the pattern of the unsteady portion which is grasped in advance as the temperature deviation pattern is extracted. The pattern is compared with the temperature deviation pattern to determine whether or not it is a joint.

Reference numeral 7 denotes a cutting machine for cutting the steel slab S according to the judgment of the tracking device 6, and 8a and 8b denote winding machines for winding in a coil shape.

FIG. 2 illustrates the tracking procedure of a billet joint according to the present invention.

[0016]

[Action] The method of joining slabs in hot rolling for the purpose of continuous rolling is as follows: induction heating causes the rear end of the preceding slab (hereinafter referred to as the preceding material) and the succeeding slab (hereinafter referred to as the succeeding material). Write)
Various types of methods have been proposed so far, such as a method in which the tips are heated and pressed against each other, or a method in which they are joined by pressing, fitting, or the like.

In any of the above methods, the temperature distribution changes around the joint between the preceding material and the succeeding material due to the joining method. In particular, in the butt joining in which the end of the plate is heated to a predetermined temperature range, the temperature is raised, and pressed, the joined portion has a higher temperature than the steady portion. Also, when positioning the preceding and following materials or pressing the preceding and following materials against each other, it is necessary to clamp the respective billets, but the clamped parts are normally stationary. The temperature is lower than that of the part.

For example, in a method of joining by heating and raising the temperature of the end of the plate and pressing the preceding material and the succeeding material together, the temperature pattern along the rolling direction near the joint is shown in FIG.
The situation is as shown in the figure.

The temperature around such a junction is measured by a thermometer 5a.
5c, and the measurement result is obtained by the tracking device 6
Into the pattern, compare it with the preset temperature pattern of the unsteady part, judge whether it is a joint, grasp the determined part as the existence area of the joint, and enter the winding device entrance side Tracking in the lead.

FIG. 4 shows a specific example of the tracking method according to the present invention.

Inside the tracking device 6, a data processing unit for extracting a non-stationary temperature pattern from the temperature distribution in the steady part of the billet is constructed. FIG. 5 sets the threshold values of the high temperature side and the low temperature side with respect to the temperature of the steady portion of the plate material,
Recognize the case where the value is more or less than that value as an unsteady part, create a temperature change pattern in this part,
An example is shown in which it is compared with a temperature pattern of an unsteady part that is grasped in advance and whether or not the part is an unsteady part is determined.

In the joining method in which the end of the plate is heated and heated, information that the highest temperature point is the joining point in the temperature pattern shown in FIG.
By providing the tracking device 6 in advance, the position of the junction in the temperature (deviation) pattern can be easily determined.

The temperature pattern can be checked by measuring the shape of the pattern (for example, a continuous shape of a low-temperature portion, a high-temperature portion, and a low-temperature portion as shown in FIG. 5) or a time interval (mass flow) between the high-temperature portion and the low-temperature portion in the pattern. Is almost constant, the time interval is almost constant irrespective of the measurement location). By combining these matching methods, the probability of erroneous detection can be extremely reduced.

In the present invention, it is preferable to appropriately update the threshold value. The reason is that due to the finish rolling and cooling of the strip, etc., the temperature deviation of the joint is reduced as going downstream, and it is difficult to detect the temperature pattern of the joint with the threshold value set at the time of measurement immediately after joining. Because it becomes. Therefore, the threshold value is updated for the temperature pattern sequentially measured, a new temperature pattern is created based on the threshold value, the pattern is stored, and the temperature of the sheet material at the downstream is detected. It is better to compare with the temperature pattern sometimes applied, and according to this, the detection error accompanying the temperature deviation is extremely reduced.

In hot rolling, there are many temperature disturbances typified by skid marks in the steel slab, but on the other hand, the temperature deviation caused by the joining method is large, and after the finish rolling or in the run-out table. Even after the cooling of the steel sheet, the detection does not become difficult.

[0026] Even in a fitting method, a pressure welding, or a joining method in which the joined portion is not heated to a higher temperature than the peripheral portion without heating the joined portion, the low-temperature portion clamped for positioning of the preceding material and the succeeding material. Of course, it is also possible to grasp the temperature pattern based only on this and track that portion in the manner described above.

As shown in FIG. 1 above, when a plurality of thermometers are provided along the longitudinal direction of the slab to measure the temperature, the temperature may be measured at the entrance of the finishing mill or the entrance of the winding machine. A method of arranging a pinch roll or a measuring roll and calculating the moving distance of the material from its rotation speed and tracking, and the tracking method according to the present invention are combined, so that the joining device is moved from the exit side to the entrance side of the winding machine. The tracking of the joint can be performed at all points in the region up to.

The measurement of the billet temperature by the thermometer plays a role of correcting the deviation of the tracking point due to the calculation error of the material speed, etc., and the more thermometers, the more advantageous in increasing the tracking accuracy at each point. It is.

The present invention does not calculate the peak value of one point of the joint in the sensor output signal, but recognizes the position of the joint by a pattern. Therefore, detection errors due to temperature change during rolling, noise of disturbance, etc. In addition, since the temperature deviation for detecting the joint is caused by the joining method, there is no need to provide a special mark for recognizing the position, and it is not necessary to introduce equipment for that. There are no benefits.

Although the temperature pattern around the joint of the steel slab differs somewhat depending on the joining method, the present invention can be applied to any joining method by grasping the temperature pattern in each method in advance. .

[0031]

【Example】

Example 1 A sheet bar having a width of 1000 mm and a thickness of 30 mm was joined by using the equipment shown in FIG. 1 above (the joining method was to heat the ends of the sheet bar by induction heating and press the ends together). Then, while tracking the joint in the following manner, hot finish rolling was performed and the coil was wound into a coil, and the tracking state of the joint at that time was investigated.

After the joining, the temperature of the sheet bar is first measured by a thermometer arranged on the entry side of the rolling mill group, and the tracking device stores the temperature pattern around the joint (at this time, the joining section). The surrounding temperature pattern was as shown in FIG. 3 described above, and the temperature pattern as shown in FIG. 5 (temperature pattern processed by the threshold value) was processed (the actual high-temperature portion temperature deviation of the junction was + 100 ° C., Although the temperature deviation of the clamp portion is −30 ° C., in this embodiment, the threshold value of the high temperature portion is + 70 ° C. and the threshold value of the low temperature portion is −20 ° C.). Compare (recognize the high-temperature part and low-temperature part thresholds as extreme values and recognize them as steady parts during that time). Then, the tracking device calculates the moving distance of the area recognized as an unsteady part based on the moving speed of the sheet bar and the like, and performs tracking until reaching the cutting machine arranged on the entrance side of the winding machine.

[0033] As a result of tracking the joint in accordance with the above procedure and cutting with a cutting machine, it was confirmed that the cutting length of the stationary part could be made shorter than in the past.

Example 2 A sheet bar having a width of 1000 mm and a thickness of 30 mm was joined using the equipment shown in FIG. 1 in the same manner as in Example 1, and the joint was tracked in the following manner, Finish rolling was carried out and coiled, and the tracking state of the joint at that time was investigated.

The tracking procedure of the joining section A thermometer is arranged on the entrance side of the finishing mill group, the exit side, and the entrance side of the cutting machine, respectively. The temperature was measured and the temperature patterns were compared in the same manner as in Example 1. In addition, the temperature was also measured with a thermometer arranged on the exit side of the rolling mill group, and the temperature patterns were compared here (extraction of the rolling mill group). On the other hand, the temperature deviation around the joint is reduced by the temperature drop during rolling, so the high temperature threshold (+ 70 ° C) and the low temperature threshold (-20 ° C) set on the entrance side of the rolling mill group , Respectively, were set at + 40 ° C. and −10 ° C., respectively, to reduce errors caused by relaxation of the temperature deviation.) Then, the temperature is measured by a thermometer on the input side of the cutting machine, the temperature pattern is compared, and for an area recognized as an unsteady portion, the moving distance is calculated based on the moving speed of the sheet bar, etc. Tracking in the lead.

As a result of tracking the joint according to the above procedure and cutting with a cutting machine, the cut-off length of the stationary part has conventionally been several meters, but according to the present invention, the cut-off length is reduced to 1 m or less. It was confirmed that it was extremely effective in improving the yield.

In the present invention, in order to increase the tracking accuracy, the pass time between clamps (t _{1 in} FIG. 5) and the pass time between the clamp and the joint (t _{2 in} FIG. 5) are also checked for matching. Such collation is advantageous in remarkably improving tracking accuracy.

[0038]

According to the present invention, the joint length of the steel slab can be accurately tracked in the continuous hot finish rolling involving the joining operation of the steel slabs, so that the cutting length of the stationary part can be reduced without adding extra equipment. Therefore, the yield can be reduced, and the yield can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of equipment suitable for use in carrying out the present invention.

FIG. 2 is an explanatory diagram of a tracking procedure of the present invention.

FIG. 3 is a diagram showing a state of a temperature distribution in a longitudinal direction of a billet.

FIG. 4 is a diagram more specifically showing a tracking procedure according to the present invention.

FIG. 5 is a diagram showing a state of a temperature distribution in a longitudinal direction of a steel slab and its temperature pattern in comparison.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rough rolling mill 2 Shear 3 Joining device 4 Rolling mill group 5a-5c Thermometer 6 Tracking device 7 Cutting machine 8a, 8b Winding machine S Billet

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI B23Q 17/20 B21B 37/00 BBM (72) Inventor Kunio Isobe 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd. Headquarters (72) Inventor Hideyuki Nikaido 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref.Examiner, Chiba Works, Chiba Works, Ltd.Examiner Yasunobu Kunikata (56) References JP-A-53-144861 (JP, A) 6-7845 (JP, A) JP-A-4-200802 (JP, A) JP-A-7-164048 (JP, A) JP-A-7-88505 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B21B 37/00-37/78 B21B 15/00 B21C 51/00 B23Q 17/20

Claims (3)

(57) [Claims] In order to continuously track the joint portion of the joined steel slab after the butt joining from the entry side of the continuous hot rolling facility to the cutting machine arranged at the exit side, continuous heat is applied. The temperature of the joining billet is continuously measured at least at one point in the region from the entry side of the cold rolling facility to the cutting machine arranged at the exit side, and the temperature deviation of the unsteady portion including the joining portion and its periphery is measured. The continuous heat is characterized by extracting the pattern of the temperature deviation and comparing the pattern of the temperature deviation with the pattern of the temperature deviation of the unsteady part which is grasped in advance to judge whether it is a billet joint. Tracking method for billet joints in hot rolling. 2. The method according to claim 1, wherein a threshold value of a high temperature portion and a threshold value of a low temperature portion of the steel slab are determined in advance, and a temperature deviation pattern of an unsteady portion is extracted based on the threshold value and the measured temperature. Item 7. The method according to Item 1. 3. A predetermined high temperature threshold and low temperature threshold are changed based on a temperature deviation pattern obtained by actual measurement, and a new temperature deviation is determined based on the changed threshold. 3. The method according to claim 2, wherein the pattern is created.