JP2004330204A - Method for electric resistance welded steel pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an electric resistance welded steel pipe by which, even in the case of using a batch type producing process by uncoiling a steel strip by each coil and feeding the uncoiled steel strip sequentially, the productivity can be made higher than that of the conventional process. <P>SOLUTION: In the method for producing electric resistance welded steel pipe, the tip end part of the steel strip of the following coil starts to run at the same speed as that of the tail end part of the preceding coil with a delay of 60 to 90 sec compared to the tail end part of the steel strip of the preceding coil. After the tip end part of the steel strip of the following coil passes through a leveler, this steel strip runs at a speed higher by 30 to 40% than the tail end part speed of the steel strip in the preceding coil. Then, the tip end part of the steel strip of the following coil passes through an edge miller at a speed of 4 to 5 m/sec and accelerated so as to become faster by 30 to 40% than the tail end speed of the preceding coil until the inlet side of a forming mill from the outlet of this edge miller and further become 4 to 5 m/min from the inlet side of the forming mill to only a first step of a fin-pass roll, and on and after the second step, the speed of the tip end part of the following coil is again returned to the same speed as the tail end speed of the preceding coil. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００２０】
その結果が図２であるが、スクイズ・ロールの出側位置での先行コイルの尾端と後行コイルの後端との時間間隔は、従来法では３分であったが、本発明では約１分と短縮できた。また、これにより、同一鋼種及びサイズの電縫鋼管の生産速度（本／時間）が従来より２０％向上した。
【００２１】
【発明の効果】
以上述べたように、本発明により、後行コイルの先端速度を製造工程の位置に応じて増速するようにしたので、生産性を従来より高めることが可能になる。
【図面の簡単な説明】
【図１】本発明に係る電縫鋼管の製造方法における先行コイルの尾端と後行コイルの先端との時間間隔を模式的に示す図である。
【図２】実施例で得た先行コイルの尾端と後行コイルの先端との時間間隔を示す図である。
【図３】従来の電縫鋼管の製造方法における先行コイルの尾端と後行コイルの先端との時間間隔を示す図である。
【図４】一般的なバッチ方式の電縫鋼管の製造工程を示すフロー図である。
【符号の説明】
１ アンコイラー
２ 鋼帯
３ エッジ・ミラー
４ ピンチローラー
５ エッジ・ベンド・ロール
６ フィンパス・ロール
７ 成形ミル
８ 高周波抵抗溶接機
９ スクイズ・ロール
１０ 管体
１１ 切削手段
１２ 超音波探傷器
１３ 焼鈍装置
１４ 水噴射ノズル
１５ サイザー
１６ 走間切断機
１７ 電縫鋼管
１８ レベラー[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an electric resistance welded steel pipe, and more particularly to a technical improvement for improving productivity in a batch-type manufacturing process in which a steel strip is rewound for each coil and sequentially fed.
[0002]
[Prior art]
An ERW steel pipe is generally manufactured by continuously forming a steel strip of a material into a cylindrical shape by a group of forming rolls while running the steel strip, and then welding the widthwise ends of the butted steel strips. . Although not shown, a steel slab obtained by continuously casting molten steel is heated to a predetermined temperature in a heating furnace and then hot-rolled into a steel strip having a constant width. This steel strip is wound into a coil having a weight of about 40 tons. Then, the coil is rewound one by one by an uncoiler and sequentially fed into a production line to form an ERW steel pipe. In this case, a method of performing a so-called “continuous operation” by integrating the rear end of the steel strip of the preceding coil (hereinafter, simply referred to as the rear end) and the front end of the steel strip of the coil to be followed (hereinafter, simply referred to as the front end) by welding. There is a method of performing discontinuous operation (also called batch operation or batch operation) at a certain distance without welding. Also, after welding the steel strips of the leading coil and the trailing coil to each other without welding, the tip of the trailing electrical resistance welded steel pipe is caused to collide with the rear end of the preceding electrical resistance welded steel pipe, and the two are meshed with each other. There is also a discontinuous operation that passes through a fixed (drawing) process (see, for example, Patent Document 1).
[0003]
Among these operations, the discontinuous operation, which is usually performed, is as follows. First, as shown in FIG. 4, after the steel strip 2 unwound by the uncoiler 1 is flattened by the leveler 18, the end mirror 3 And the steel strip surface is fed at a constant speed to a group of forming mills 7 starting from the edge bend roll 5 and ending with a multi-stage fin pass roll (only one stage is shown) 6. The steel strip 2 formed into a cylindrical shape by these forming mills 7 is heated by a high-frequency resistance welding machine 8 or the like at the butted end in the width direction (hereinafter, simply referred to as a butted portion or a seam portion), and is squeezed and rolled. And press-bonded and welded to form a temporary pipe 10. Since a bead (not shown, but a thread-like projection formed on a normal welded portion) is formed on the inner and outer surfaces of the pipe 10 by the above welding, the bead is cut and removed by the cutting means 11. Further, after the flaw inspection by the ultrasonic flaw detector 12, as a heat treatment, annealing of the welded portion (the seam portion) and cooling by the water injection nozzle 14 are sequentially performed by the annealing device 13 as a seam aniler. Thereafter, the size is adjusted by a drawing mill such as a sizer 15 and then cut to a desired length by a running cutter 16 on a transfer line for dispensing to form an ERW steel pipe 17 having desired characteristics. . In addition, when the joining method is replaced by the above-mentioned welding and forged, a forged steel pipe is obtained.
[0004]
By the way, the current state of manufacturing the electric resistance welded steel pipe 17 through such a discontinuous operation process with the steel strip 2 having a thickness of 19 mm and a width of 2200 mm is represented by a time interval between the tail end position of the preceding coil and the tip end position of the following coil. As shown in FIG. That is, 90 seconds after the tail end of the preceding coil passes through the leveler exit side, the following coil passes through the leveler exit side. The tip speed is the same as the tail speed of the preceding coil. Then, the tip is once decelerated (this is referred to as an E / M threading speed) so as to bite into the edge mirror (symbol: E / M), and then returned to the tail end speed of the preceding coil again. After that, since it takes time to weld with a squeeze roll (symbol: SQ), when the leading end of the following coil reaches the entry side of the fin pass roll (symbol: FP), which is the final rolling mill of the forming mill, Then, the speed is reduced again until reaching the exit side of the squeeze roll (referred to as a threading speed between FP and SQ), and thereafter, the speed is returned to the initial speed.
[0005]
Therefore, when compared at the exit side position of the squeeze roll, the tail end of the preceding coil and the front end of the following coil have an interval of about 3 minutes in time, and the productivity in the batch-type ERW pipe manufacturing process is reduced. Was a factor in inhibiting
[0006]
[Patent Document 1]
JP-A-6-198330
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a method of manufacturing an electric resistance welded steel pipe capable of increasing productivity as compared with the conventional method even when using a batch-type manufacturing process in which a steel strip is unwound and sequentially fed for each coil. It is an object.
[0008]
[Means for Solving the Problems]
The inventor conducted intensive research to achieve the above object, and realized the results in the present invention.
[0009]
That is, in the present invention, the steel strip is rewound for each steel strip coil by an uncoiler, straightened by a leveler, trimmed with an edge mirror, formed into a cylindrical shape by a forming mill, and then butted. The seam part is heated with an induction coil, pressed with a squeeze roll, crimped, and welded to form a tubular body.In the method of manufacturing an ERW steel pipe, the tip of the steel strip of the following coil is attached to the tail end of the steel strip of the preceding coil. The running starts at the same speed as the tail end speed of the preceding coil with a delay of 60 to 90 seconds, and after the steel strip tip of the following coil passes through the leveler, runs at a speed 30 to 40% faster than the tail end speed of the preceding coil, The leading end speed of the steel strip of the succeeding coil passes through the edge mirror at a speed of 4 to 5 m / min, and the distance from the exit side of the edge mirror to the entrance side of the forming mill is 30 times lower than the tail end speed of the preceding coil. Speed up to ~ 40% faster, An electric resistance welded steel pipe characterized in that only the first stage of the fin pass roll is set at 4 to 5 m / min from the entry side of the forming mill, and the second stage and subsequent stages are returned to the same speed as the tail end speed of the preceding coil. Is a manufacturing method. In this case, the tail end speed of the preceding coil is preferably 10 to 40 m / min, and more preferably 12 to 20 m / min.
[0010]
According to the present invention, even if a batch-type manufacturing process in which a steel strip is unwound and sequentially fed for each coil is used, the tip speed of the succeeding coil is increased according to the position of the manufacturing process. Therefore, it is possible to increase productivity more than before.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described, taking into account the circumstances that led to the invention.
[0012]
An object of the present invention is a method of manufacturing a so-called "batch type" ERW steel pipe in which a steel strip coil is rewound one by one by an uncoiler and sequentially sent to a manufacturing process. That is, as shown in FIG. 4, after the steel strip 2 unwound by the uncoiler 1 is trimmed with the edge mirror 3, a group of steel strips starting with the edge bend roll 5 and ending with the multi-stage fin pass roll 6 is formed. After being formed into a cylindrical shape by the forming mill 7, the butted seam portion is heated by a high-frequency resistance welding machine 8, pressed by a squeeze roll 9, pressed and welded to produce an ERW steel pipe 17 to be a pipe body 10. The process is used to improve the operation method.
[0013]
Therefore, if the time interval (see FIG. 3) between the tail end position of the leading coil and the leading end position of the following coil in the conventional operation method described above can be shortened by about 3 minutes, the productivity is improved. The possible positions in the manufacturing process were studied. As a result, they have found that it can be realized in the following several places, and have completed the present invention. Hereinafter, the present invention will be described with reference to FIG. 1, which schematically shows a time interval between the tail end of the preceding coil and the front end of the following coil in the manufacturing method according to the present invention. In this example, a steel strip coil having a width of 1930 mm, a thickness of 22 mm, and a length of 110 m manufactured by hot rolling is used.
[0014]
First, 90 seconds after the tail end of the preceding coil passes through the leveler exit side, the running of the leading end of the following coil at the same speed as the tail end speed of the preceding coil is started by setting the following coil in the uncoiler. The 90 seconds cannot be reduced so much because the time is limited. However, according to a worker having a high level of skill in the setting operation, the time can be reduced to 60 seconds. Therefore, the lower limit is set to 60 seconds. Note that the tail end speed of the preceding coil varies depending on the type and size of the material steel of the steel pipe, but is set to 10 to 40 m / min in the present invention. If it is less than 10 m / min, it is too slow with respect to the current facility capacity, and if it exceeds 40 m / min, it is too fast.
[0015]
Next, the tip of the succeeding coil is once decelerated so as to bite into the edge mirror (symbol: E / M) (this is referred to as E / M threading speed), and then again to the tail end speed of the preceding coil. For returning, the E / M threading speed was reduced to 4 to 5 m / min. The reason why the upper limit of the deceleration is set to 5 m / min is that if the speed is higher than this, the effect of the deceleration is not exhibited, and the tip of the coil may not be smoothly engaged with the edge mirror. Further, the lower limit of the deceleration is set to 4 m / min, because the biting is sufficiently performed at that speed.
[0016]
Subsequently, after the tip has passed through the edge mirror, the speed is conventionally returned to the above-mentioned constant speed. However, there is only a pinch roll up to the entry side of the forming mill, and there is nothing that causes a large resistance (obstacle) in running. Therefore, we examined whether the speed increase was possible in that section. As a result, it was found that the speed from the exit side of the edge mirror to the entry side (symbol: PF) of the forming mill can be increased to a speed that is 30 to 40% higher than the tail end speed of the preceding coil. If it is less than 30%, the speed-up effect is too small, and if it is more than 40%, it is too fast and the transport capacity is insufficient, which is inconvenient.
[0017]
Then, the head is driven at the same speed as the tail end speed of the preceding coil from the entry side of the forming mill to the entry side of the fin pass roll. : FP), the speed was reduced again (referred to as the threading speed between FP and SQ) until the squeeze roll reached the exit side. Therefore, the inventor has intensively reviewed the deceleration from the entrance of the fin pass roll to the exit of the squeeze roll. As a result, no problem occurs even if only the first stage of the fin-pass rolls arranged in multiple stages is reduced to 4 to 5 m / min and the second stage and subsequent stages are returned to the same speed as the tail end speed of the preceding coil. Was found as an important point of the present invention. The reason why the deceleration is set to 4 to 5 m / min is that if the speed exceeds 5 m / min, the deceleration effect cannot be exerted, and the leading end does not bite into the roll smoothly, and if the speed is 4 m / min, it bites.
[0018]
【Example】
Using the manufacturing process of the ERW steel pipe shown in FIG. 4, a number of ERW steel pipes were manufactured by the conventional method and the manufacturing method according to the present invention. The product has an outer diameter of 609.6 mmφ x a wall thickness of 22 mm, the leading end speed of the preceding coil at which the steel strip starts traveling from the uncoiler is 14 m / min, and the trailing coil has a trailing end of the leading coil. Running was started 90 seconds after leaving the uncoiler. FIG. 2 schematically shows this state. Table 1 shows the speeds of the steel strip or the pipe running in the manufacturing process in the conventional example and the present invention example.
[0019]
[Table 1]

[0020]
The result is shown in FIG. 2. The time interval between the tail end of the preceding coil and the rear end of the following coil at the exit position of the squeeze roll was 3 minutes in the conventional method, but was about 3 minutes in the present invention. It was reduced to one minute. This also increased the production speed (book / hour) of ERW steel pipes of the same steel type and size by 20% compared to the conventional case.
[0021]
【The invention's effect】
As described above, according to the present invention, the tip speed of the following coil is increased in accordance with the position of the manufacturing process, so that the productivity can be increased as compared with the related art.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a time interval between a tail end of a preceding coil and a tip of a following coil in the method for manufacturing an electric resistance welded steel pipe according to the present invention.
FIG. 2 is a diagram showing a time interval between a tail end of a leading coil and a tip end of a following coil obtained in the embodiment.
FIG. 3 is a diagram showing a time interval between a tail end of a preceding coil and a front end of a following coil in a conventional method of manufacturing an electric resistance welded steel pipe.
FIG. 4 is a flowchart showing a manufacturing process of a general batch-type ERW steel pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Uncoiler 2 Steel strip 3 Edge mirror 4 Pinch roller 5 Edge bend roll 6 Fin pass roll 7 Forming mill 8 High frequency resistance welding machine 9 Squeeze roll 10 Tube 11 Cutting means 12 Ultrasonic flaw detector 13 Annealing device 14 Water Injection nozzle 15 Sizer 16 Cutting machine during running 17 ERW steel pipe 18 Leveler

Claims (2)

After rewinding the steel strip for each steel strip coil with an uncoiler, correcting the distortion with a leveler, trimming the end with an edge mirror, shaping it into a cylindrical shape with a forming mill, and then abutting the seam part with an induction coil In the method of manufacturing ERW steel pipes, which are heated with squeeze rolls, pressed with
The leading end of the steel strip of the succeeding coil starts running at the same speed as the tail end speed of the leading coil with a delay of 60 to 90 seconds behind the leading end of the steel strip of the leading coil, and after the leading end of the steel strip of the following coil passes through the leveler, It travels at a speed that is 30 to 40% faster than the tail end speed of the preceding coil, and the steel strip tip speed of the following coil passes through the edge mirror at a speed of 4 to 5 m / min, and from the exit side of the edge mirror. The speed up to the entry side of the forming mill is increased so as to be 30 to 40% faster than the tail end speed of the preceding coil, and only the first stage of the fin pass roll from the entry side of the forming mill becomes 4 to 5 m / min. And returning the second and subsequent stages to the same speed as the tail end speed of the preceding coil again. The method for manufacturing an electric resistance welded steel pipe according to claim 1, wherein the tail end speed of the preceding coil is set to 10 to 40 m / min.

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