JP3458059B2 - Multi-strand continuous rolling method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous rolling method and apparatus for multi-strand hot rolling of strip metal, particularly strip steel.

[0002]

2. Description of the Related Art In the hot rolling of a strip metal, for example, a strip steel, a rolled material is charged into a heating furnace through an inlet of a heating furnace and heated, and then an extraction end arranged on the opposite side of the heating furnace. The rolled material that has been heated is extracted and supplied to the rolling line to start rolling. Side extraction to extract the rolled material from the side with respect to the rolling material moving direction in the heating furnace and supply it to the rolling line,
There is a forward extraction that extracts in the forward direction of the rolling material movement direction, but in both cases, the arrangement in which the heating furnace and rolling mill are as close as possible is adopted, which allows rolling to start before the heated rolling material is cooled. .

In strip rolling, productivity is improved by adopting multi-strand rolling in which a plurality of rolled materials are simultaneously rolled in rough rolling and intermediate rolling. In the multi-strand rolling, a roll having a plurality of calibers is adopted in a rough rolling mill and an intermediate rolling mill, and the same number of rolled materials as the caliber number is supplied to the rough rolling mill and simultaneously rolled.

Also in multi-strand rolling, an arrangement in which the heating furnace and the rolling mill are as close to each other as possible is adopted. In the case of multi-strand rolling, the extraction part of the heating furnace is provided with an extraction line equal in number to the number of strands, and the rolled material that has been heated is sequentially supplied to each extraction line. It is supplied to each strand to start rolling.

Conventionally, in rolling, a rolled material having a predetermined length is individually rolled by each strand. In this case, the leading and trailing end portions of the rolled material are not subjected to tension during rolling, so that the dimensions are deviated, and the leading and trailing edges of each rolled material are forced to be trimmed. Further, since the rolled material after finish rolling has a small cross-sectional area and a high rolling speed, passing of the rolled material tip where tension is not applied is unstable, and a misroll due to tipping or the like is likely to occur. Currently, in the field of wire rods, the speed of rolling is increasing, and the speed of progress after finish rolling is 10 per second.
It has reached 0 m or more. Further, since the secondary processing step using the wire rod as a material is omitted, the diameter of the product after rolling the wire rod is being reduced, and the probability of misrolling is increasing due to the speedup and the diameter reduction.

A continuous rolling method is known in which the trailing end of the preceding rolled material that has started rolling and the leading end of the trailing rolled material extracted from the heating furnace are sequentially joined to perform endless rolling. If this continuous rolling method is adopted, the trimming loss at the leading and trailing edges of the rolled material and the occurrence of misrolls at the rolled material tip in conventional discontinuous rolling are greatly reduced. Continuous rolling has been conventionally known for hot rolling of steel sheets or for single strand rolling even for strips. In continuous rolling, a traveling joining device is arranged between the extraction end of the heating furnace and the rolling mill. The running joining device runs along with the preceding material that has started rolling, and joins the trailing end of the preceding material and the leading end of the following material extracted from the heating furnace while running.

[0007]

In the conventional continuous rolling, the extraction end of the heating furnace and the welding start position by the traveling joining device are similar to the case where the extraction end of the heating furnace and the rolling mill are arranged as close as possible in the discontinuous rolling. The arrangement was used to bring them as close as possible. This is to prevent heat loss of the rolled material as much as possible. The traveling speed of the following material after the start of joining is naturally the same as the rolling speed of the first rolling mill. Since the joining start position is near the extraction end of the heating furnace, the trailing end of the trailing material after the joining is initially left on the extraction line in the heating furnace.
In the multi-strand rolling, if the trailing material of the strand on the front side (charging side) of the heating furnace in the advancing direction remains on the extraction line, the next rolled material after heating is moved to the back side of the heating furnace in the advancing direction ( It cannot be supplied to the strand on the extraction side). In the meantime, if the trailing edge of the preceding material that has started rolling with the strand on the back side passes the joining start position, the strand cannot join the preceding material and the following material, and continuous rolling must be interrupted. It is a situation that can not be obtained.

It is an object of the present invention to provide a continuous rolling method and apparatus capable of supplying a rolled material without interrupting continuous rolling for each strand in multi-strand continuous rolling.

[0009]

Means for Solving the Problems That is, the gist of the present invention is as follows: (1) In a multi-strand continuous rolling method, a trailing material that is rolled with the same strand as the trailing edge of the preceding material that has started rolling When rolling while joining the tip of the rolled material by a joining device that travels with the rolled material, the distance between the rolled material extraction end of the heating furnace and the joining start position of the joining device is at least the length of the rolled material or more. Continuous rolling method. (2) The rolling start time of the first rolled material of each strand is such that the leading end of the trailing material of the strand reaches the joining start position when the trailing end of the first strand passes the joining start position. As described above, the rolling start time of the first rolled material is adjusted, and the continuous rolling method according to (1) above. (3) The rolling start time of the first rolled material is from the scheduled time when the tip of the trailing material arrives at the joining start position,
The heat according to (2) above, which is after a time after subtracting a scheduled elapsed time from the start of the rolling of the first strip to the arrival of the rear end of the first strip at the joining start position. Hot rolling method. (4) A multi-strand continuous rolling apparatus, in which a trailing end of a preceding material that has started rolling and a leading end of a following material that is rolled with the same strand are joined together while running together with the rolled material A continuous rolling mill, which is provided between the rolling mill and a rolling mill, and the distance between the rolled material extraction end of the heating furnace and the joining start position of the joining device is at least the length of the rolled material. Is.

According to the present invention, as shown in FIG. 3, since the distance between the rolled material extraction end 10 of the heating furnace 1 and the joining start position 11 of the joining device 3 is at least the length of the rolled material 17 or more, the heating furnace The rolled material 17 supplied to the extraction line 2 of each strand from 1 immediately travels and the tip of the rolled material reaches the joining start position 11 of the joining device.
The rear end of the rolled material is immediately discharged from the extraction line 2 in the heating furnace. As a result, even if the joining of the trailing material is started in the strand on the front side in the heating furnace advancing direction of the multi-strand rolling, the trailing end of the trailing material has already exited the heating furnace extraction end 10 It becomes possible to supply the subsequent rolled material to the extraction line of the strand on the back side in the direction.

In FIG. 3, when the leading end of the rolled material 17d of the second strand 21 reaches the rolling start position 11, the trailing end of the rolled material 17d has passed through the extraction end 10 of the heating furnace, and therefore follows. It is possible to supply the rolled material to the extraction line of the first strand 20. On the other hand, in FIG. 4, since the distance between the extraction end 10 of the heating furnace and the joining start position 11 is shorter than the length of the rolled material 17, the second strand 2
At the time when the tip of the first rolled material 17d reaches the joining start position 11, the rear end of the rolled material 17d still remains in the extraction line of the heating furnace. Can't feed line.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The outline of the present invention will be described with reference to FIG. The structure of the extraction unit of the heating furnace 1 is such that the rolled material is extracted from the side in the moving direction of the rolled material in the heating furnace and is supplied to the rolling line, and the extraction is performed in the forward direction of the moving direction of the rolled material. There is forward extraction, and either can be adopted. FIG. 1 employs lateral extraction. Lateral extraction is excellent in order to start rolling without taking heat of the extraction material as much as possible. In the extraction part of the heating furnace that employs the multi-strand rolling, the extraction line 2 is provided at the end of the heating furnace 1 on the far side 23 in the traveling direction, the number being equal to the number of strands.

A joining device 3 is provided on the extension of the heating furnace extraction line 2.
However, a rolling mill is arranged further ahead. Here, the rolled material extraction end 10 of the heating furnace is an extension of the extraction line 2 and an outlet portion from the side wall of the heating furnace 1. The length of the rolled material 17 is usually equal to the maximum length of the rolled material that can be charged into the heating furnace.

At the time of joining the rolled materials, one of the rolled materials to be joined is rolling and is running, so the joining device 3
Also, a traveling joining device that travels together with the rolled material is used. Therefore, the joining device 3 can travel in a predetermined section between the heating furnace 1 and the rough rolling mill 4.

In the present invention, the joining start position 11 refers to a position where a portion to be joined of the rolled material exists at a position where the joining device 3 starts traveling together with the rolled material for joining. The joining start position 11 is selected within the region of the joining device travelable range 15 shown in FIG. 2A, but in the present invention,
The position where the joining device is closest to the rolling mill is the joining end position 1
2, and a position returned from the joining end position 12 to the heating furnace side by a distance traveled while the joining apparatus is performing joining is the joining start position 11 of the present invention. That is, the joining start position 11
From the joining position to the joining end position 12 is the joining device running range 14 during joining. By setting in this way, the distance between the heating furnace extraction end 10 and the joining start position 11 can be maximized, and the distance between the heating furnace 1 and the rough rolling mill 4 becomes unnecessarily long. Can be prevented. The distance traveled by the welding device while the welding is performed by the welding device 3 is determined by the required welding time and the traveling speed of the rolled material.

In the multi-strand rolling for strips, it is difficult to arrange a separate traveling joining device for each strand because the distance between the strands is small. If you try to place the joining device for each strand by force, the running range of the joining device of each strand will be placed so as not to interfere with each other, and the length occupied by the joining device from the heating furnace to the rolling mill is long. Therefore, it is not preferable from the viewpoint of equipment construction cost and heat loss of the rolled material. Therefore,
The joining device in the multi-strand continuous rolling is preferably a method in which all the strands are joined by one joining device by traversing the joining device between the strands. In FIG. 2, (a) and (b) are positions where the joining device joins the rolled material of the second strand 21,
(C) is a position where the joining device joins the rolled material of the first strand 20.

As a method of joining the preceding material and the following material, butt welding methods such as upset welding method and flash butt welding method, which are capable of joining the end surfaces of the rolled materials over the entire surface, are suitable. In order to reduce the cross-sectional area while rolling the steel bar or wire rod, etc. while three-dimensionally largely deforming with a roll having a caliber hole type, it is necessary to firmly join so that the joint part does not break during rolling, At the same time, it is necessary to reduce the yield loss due to joining as much as possible, but these conditions can be satisfied by the above butt welding method.

Since the upset welding method is resistance welding under pressure, it is difficult to join the entire surface unless the end faces of the rolled material are processed flat. On the other hand, in the flash butt welding method, since the joining surfaces are melt-joined by flash and then pressure is applied, if the flatness is maintained to some extent, the entire surface joining is possible without end face processing. Therefore, the flash butt welding method is optimal as a method for joining rod-shaped rolled materials such as those used as rolled materials for bar steel and wire rods.

In flash butt welding, the leading material and the trailing material are held by holders that also serve as electrodes, and then the trailing edge of the leading material and the leading edge of the trailing material are brought into contact with each other, and the Joule heat and Butt welding is performed by using the arc heat generated after the contact portion melts and scatters. In order to pass a large current in flash butt welding, it is necessary to suppress the current loss as much as possible, and in order to prevent electrode damage due to sparks, remove the scale on the rolled material surface of the electrode contact part before welding. Is mandatory. Also, in flash butt welding, burrs always occur at the joint, so
A deburring device 16 is provided between the welding device and the rolling mill in order to prevent the burrs from falling off during rolling and biting into the rolled material to form foreign matter biting flaws.

In the present invention, there is a space for one rolled material between the heating furnace extraction end 10 and the joining start position 11. In order to avoid heat loss of the rolled material in this portion, it is effective to install a heat insulating cover so as to cover the transportation path of the rolled material in this portion.

Even in continuous rolling in which endless rolling is performed, the rolling operation itself is no different from the conventional batch type rolling. In the winding or bundling process in the bundling device 9 after the end of rolling, the weight of the wound material exceeds the manageable weight if it is endless, so the rolled material is cut into predetermined lengths after the end of rolling. To do.

Continuous rolling of each strand Since the first rolled material of the first rolling does not have a material being rolled prior to the material of the strand, the first rolled material is rolled immediately after extraction from the heating furnace. It is also possible to convey to the mill and start rolling. On the other hand, for extraction of the subsequent rolled material from the heating furnace, it is sequentially performed based on the heating time of the heating furnace, and in multi-strand rolling, the subsequent rolled material of the strand after extraction of the rolled material of the strand other than the strand. Is extracted. Therefore, since a considerable amount of time is required from the extraction of the preceding material to the extraction of the following material, if the first rolling of the continuous rolling is immediately started, the trailing edge of the preceding material will be removed before the succeeding material is extracted. It will pass the joining start position, making it impossible to join the trailing material. In FIG.
Since the first rolled material 17a of the first strand 20 was started to be rolled immediately after being extracted from the heating furnace, when the tip of the succeeding rolled material 17b reaches the rolling start position 11, after the first rolled material 17a The end has passed the rolling start position 11, and it is impossible to join the two. On the contrary, if the first rolling of the continuous rolling is started too late, the trailing edge of the first rolled material remains on the heating furnace side of the welding starting position when the leading edge of the trailing material reaches the welding starting position 11. However, there is a problem in that the trailing end of the following material is prevented from being discharged from the heating furnace.

In the present invention, in order to solve the above problems, the rolling start time of the first rolled material of each strand is
Adjusting the rolling start time of the first rolled material so that the leading end of the trailing material of the strand reaches the joining starting position when the first trailing end passes through the joining starting position 11. Is characterized by. Further, the rolling start time of the first rolled material is the time when the leading end of the trailing material arrives at the joining start position 11 from the scheduled time when the first rolling is started and the trailing end of the first rolled material is The first and second joinings can be reliably performed by setting the time to be after the scheduled elapsed time until reaching the joining start position 11. The scheduled time at which the tip of the trailing material arrives at the joining start position can be easily predicted from the heating schedule, and the first trailing end reaches the joining start position after the first rolling is started. The estimated elapsed time up to is also easily predictable from the rolling speed.

[0024]

EXAMPLES The present invention was carried out in a three-strand steel wire rod rolling facility shown in FIG. Rough rolling mill 4 and No. In one intermediate rolling mill 5, three strands are rolled using a roll having three calibers, and thereafter, for each strand,
No. 2 Rolling is performed in the intermediate rolling mill 6 and the finish rolling mill 7. The rolled wire rod is cooled by the adjusting cooling facility 8 and then focused by the focusing device 9 to obtain a product. As rolling material 122
Use a billet with a length of 18 mm square and 5 mm to 18 mm
Roll to a wire with a diameter of mm. The heating furnace 1 has one walking beam type continuous heating furnace.

The rolled material is supplied from the heating furnace 1 to the rolling mill.
Three lines of extraction line 2 on the far side 23 of the rolling direction of the heating furnace
From the extraction line, each strand (20,
21 and 22) is supplied with the rolled material 17.

Rolling material extraction end 10 of heating furnace 1 and rough rolling mill 4
The joining device 3 of the present invention was arranged between the two. Joining device 3
Runs with the rolled material (predecessor material) that started rolling,
The trailing end of the preceding material and the leading end of the following material are clamped by electrodes, and both are joined by flash butt welding. The traveling range 15 of the joining device is 3.5 m in the rolling direction. By traversing the joining device 3 at right angles to the rolling direction, the joining of the rolled material of three strands is performed by one joining device. The distance traveled by the welding device when the welding is performed once (the welding device traveling range 14 during welding) is 2.6 m. Therefore, from the position where the joining device 3 is closest to the rolling mill to the heating furnace side.
The joining position of the joining device 3 at the position moved by 6 m is referred to as the joining start position 11 of the present invention. In this embodiment, the heating furnace 1
The distance from the rolled material extraction end 10 to the joining start position 11 of the joining apparatus 3 was set to 26 m. Since the maximum length of the rolled material 17 is 18 m, the distance between the rolled material extraction end 10 of the heating furnace and the joining start position 11 of the joining device is equal to or longer than the length of the rolled material.

In the rolled material 17 having a length of 18 m, it takes about 3 minutes from the start of the rolling of the leading end of the rolled material 17 in the first stage of the rolling mill to the insertion of the trailing end into the rolling mill. On the other hand, the extraction of the rolled material from the heating furnace is a minimum of 60 seconds per one, and since the rolled material is supplied to three strands, it is necessary to extract the preceding material of the same strand and the subsequent material. The minimum time required is 180 seconds. Further, the time required to bond the rolled material with the bonding device is about 48 seconds for occupying the bonding device per bonding (cycle time of electrode gripping-bonding-gripping release-other strand movement). Therefore, the end of one rolled material is joined by the joining device, the rolled material is further inserted into the rolling mill, and the next end of the strand is inserted until the rear end of the material reaches the joining start position of the joining device. The rolled material has finished extraction from the heating furnace and the tip of the rolled material has reached the joining start position. In this way, the rolled material of each strand is sequentially joined while being rolled, and endless continuous rolling can be carried out.

As shown in the second strand 21 of FIG.
At the time when the tip of the trailing material 17d reaches the joining start position 11 and joining with the trailing end of the preceding material 17c is started,
The trailing end of the rolled material 17d as the following material is the heating furnace extraction end 10
Since the passage of No. 2 has been completed, no succeeding material remains in the extraction line 2 in the heating furnace. Therefore, the rolled material of another strand following in the heating furnace can reach the extraction line of its own strand without being disturbed by the rolled material 17d.

Regarding the first rolled material in continuous rolling, even if the rolled material is extracted from the heating furnace and the leading end of the rolled material arrives at the rolling mill, rolling is not started immediately. When rolling is started 120 seconds after the arrival, the rear end of the rolled material reaches the joining start position 60 seconds after the start of rolling. Then, at the same timing, the leading end of the trailing material of the same strand is extracted from the heating furnace and arrives at the rolling start position, so that they can be joined.

Continuous rolling according to the present invention was carried out by joining 10 billets on average. Since the trimming in rolling may be performed only at the leading edge and the trailing end of continuous rolling, the yield loss due to trimming loss was reduced by 90% as compared with the case of discontinuous rolling, and the yield improvement could be realized. In addition, the frequency of misrolling due to tipping etc. is 0.0 in conventional discontinuous rolling.
What was generated by 1% is 0.001 by continuous rolling
% Has been reduced. Further, since the rolling interval between the preceding material and the following material in the discontinuous rolling was reduced, the production efficiency was improved and the production capacity could be increased by 5%.

[0031]

EFFECT OF THE INVENTION By setting the distance between the rolled material extraction end of the heating furnace and the joining start position of the joining device to be at least the length of the rolled material of the present invention, the strand on the front side in the heating furnace advancing direction of multi-strand rolling Even if the joining of the trailing material is started in, the trailing end of the trailing material has already exited the heating furnace extraction end, so the subsequent rolled material is supplied to the extraction line of the strand on the back side in the heating furnace advancing direction. It has become possible. This allows
Endless continuous rolling is possible with the multi-strand rolling equipment, and it has been possible to improve yield by reducing trimming loss, improve yield and production capacity by reducing misrolls, and improve production capacity by continuation.

[Brief description of drawings]

FIG. 1 is an overall view of a continuous rolling apparatus of the present invention, showing a state in which a joining device is located at a joining start position of a second strand.

FIG. 2 is a partial view of the continuous rolling apparatus of the present invention, in which the joining apparatus is located at the position closest to the heating furnace of the second strand in (a) and the position of the second strand closest to the rolling machine in (b). 2 (c) is a diagram showing a situation in which the first strand is located at a position closest to the rolling mill.

FIG. 3 is a partial view showing a continuous rolling method of the present invention.

FIG. 4 is a partial view showing a conventional continuous rolling method.

FIG. 5 is a diagram showing a situation of the first continuous rolling.

[Explanation of symbols]

1 heating furnace 2 extraction lines 3 joining device 4 rough rolling mill 5, 6 Intermediate rolling mill 7 Finishing mill 8 Adjustment cooling equipment 9 Focusing device 10 Extraction end 11 Joining start position 12 Joining end position 13 Position of the welding equipment at the position closest to the heating furnace 14 Running range of joining device during joining 15 Possible range of joining device 16 Deburring device 17 Rolled material 18 joints 20 First Strand 21 Second Strand 22 Third Strand 23 Back side 24 Loading side

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Makio Kikuchi 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation (56) References Japanese Patent Laid-Open No. 53-94250 (JP, A) Kai 54-2254 (JP, A) JP 53-135852 (JP, A) JP 8-155513 (JP, A) JP 10-287916 (JP, A) (58) Fields investigated (58) Int.Cl. ⁷ , DB name) B21B 1/00-1/46 B21B 37/00-37/78

Claims (4)

(57) [Claims] 1. In a multi-strand continuous rolling method, when a trailing end of a preceding material that has started rolling and a leading end of a following material that is rolled in the same strand next are joined and rolled by a joining device that travels together with the rolled material, A continuous rolling method, wherein the distance between the rolled material extraction end of the heating furnace and the joining start position of the joining device is at least the length of the rolled material. 2. The rolling start time of the first rolled material of each strand is such that when the trailing end of the first strand passes the joining start position, the leading end of the trailing material of the strand reaches the joining start position. The continuous rolling method according to claim 1, wherein the rolling start time of the first rolled material is adjusted as described above. 3. The rolling start time of the first rolled material is
A time obtained by subtracting a scheduled elapsed time from the start of the rolling of the first strip to the arrival of the rear end of the first strip from the scheduled time at which the tip of the trailing strip arrives at the joining start position. The hot rolling method according to claim 2, wherein the hot rolling method is performed after the hot rolling. 4. A multi-strand continuous rolling apparatus, wherein a joining apparatus for joining a trailing end of a preceding material that has started rolling and a leading end of a following material that is then rolled with the same strand while running together with the rolled material is a heating furnace. And a rolling mill, and the distance between the rolled material extraction end of the heating furnace and the joining start position of the joining device is at least the length of the rolled material or more.