JP3580197B2 - Manufacturing method of seamless steel pipe - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
In the present invention, when manufacturing seamless steel pipes using a Mannesmann mandrel mill or the like, even if products of different dimensions are aggregated for the same material, the excess product is eliminated as much as possible to reduce the yield. The present invention relates to a method for manufacturing a seamless steel pipe that can be improved.
[0002]
[Prior art]
In the Mannesmann mandrel mill method for manufacturing seamless steel pipes, the wall thickness is determined by the piercer plug and mandrel bar, and the outer diameter is determined by the sizer roll. Has the characteristic that products of various sizes can be manufactured from, and the production efficiency is high.
[0003]
Therefore, because of the advantages described above, even products of various dimensions required by customers can be manufactured at low cost, and many of the seamless steel pipe manufacturing facilities are manufactured using the Mannesmann mandrel mill method. Has been adopted.
[0004]
[Problems to be solved by the invention]
By the way, seamless steel pipes, which are products, are often required in large quantities for products of the same dimensions, such as line pipes and oil country tubular goods, but recently, orders for small lots such as structural steel pipes have been increasing. When ordering such a small lot or short tube, if the length of the material billet is restricted by the lower limit due to conveyor conveyance etc., the material billet must be taken longer than necessary, Material design for pipe making had to be designed, and the production of more than the number ordered was forced, resulting in a large yield loss.
[0005]
As described above, recently, an increase in yield loss due to the occurrence of surplus due to small lot orders has caused a cost increase.
As a method for improving the yield of such rolled material, there is a method in which a cutting length arrangement method is devised, but in particular, a method in which surplus is reduced in advance for small lot materials having different product dimensions. There was no.
[0006]
The present invention has been made in view of the above-described problems, and has as its object to provide a method for manufacturing a seamless steel pipe that is devised so as to reduce surplus in advance for small lot materials having different product dimensions.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described object, the method for manufacturing a seamless steel pipe according to the present invention secures a material length equal to or more than the material constraint lower limit length by consolidating the same material even for products having different dimensions, after heating to convey the material, the control unit disconnects instructs the required length to the cutting machine, then sizer to sizer so that each material with the controller disconnects becomes a predetermined product dimension Rolling is instructed to change the roll interval . By doing so, the production of surplus products is suppressed as much as possible, and the product yield is improved.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
A method for manufacturing a seamless steel pipe according to the present invention includes a rolling mill capable of adjusting a product size according to an instruction from a control device, and a cutting machine that cuts a heated material downstream from a heating furnace according to an instruction from the control device. This is a method of manufacturing seamless steel pipes on a production line in which the same material is consolidated even for products of different dimensions, ensuring a material length equal to or longer than the lower limit of material constraints, and transporting this material. after to heating, the controller disconnects instructs the required length to the cutting machine, then, the material that the control device is cut becomes a predetermined product dimension (a predetermined outer diameter, wall thickness) In this way, rolling is performed by instructing the sizer to change the size of the sizer roll .
[0009]
In the method for manufacturing a seamless steel pipe according to the present invention, even if products of different dimensions are aggregated for the same material, a material length equal to or more than the material constraint lower limit length is secured, and the material is transported and heated. , the control unit disconnects instructs the required length to the cutting machine, then the controller instructs the sizer to the interval changes sizer roll so that each material taken is a predetermined product dimensions rolling Therefore, it is possible to prevent the production of surplus products as much as possible and to improve the product yield.
[0010]
【Example】
Hereinafter, a method for manufacturing a seamless steel pipe according to the present invention will be described with reference to FIG.
FIG. 1 (a) is an explanatory diagram for manufacturing order lots A and B according to the method of the present invention, (b) is an explanatory diagram for manufacturing order lot A by a conventional method, and (c) is an order lot according to a conventional method. It is explanatory drawing in the case of manufacturing B.
[0011]
In carrying out the method for manufacturing a seamless steel pipe according to the present invention, a rolling mill capable of adjusting product dimensions and a manufacturing line in which a cutting machine is arranged downstream of a heating furnace are required.
First, lots of the same material category and of the same product size or lots of the same material category and appropriately close product dimensions are grouped and combined with the same material to make them longer than the material constraint lower limit length of the production line.
[0012]
For example, one piece of 0.2% carbon steel having an outer diameter of 300 mm, a thickness of 10.0 mm, and a length of 6 m (order lot A) has an outer diameter of 302 mm, a thickness of 10.5 mm, and a length of 5 m. In the case of receiving an order of two (order lot B) of 0.2% carbon steel, a seamless steel pipe production line with a material constraint lower limit length of, for example, 1.7 m (converted product length: 13 m) As shown in FIG. 1 (a), the above-mentioned order lot A and order lot B are consolidated into a material (billet) having the same outer diameter of 300 mm as shown in FIG. , For example, 2 m 160 mm.
[0013]
Next, after transporting the above-described material and performing required heating in the heating furnace, the control device instructs a cutting machine arranged downstream of the heating furnace to supply one material A for the A lot and one material for the B lot. Material B is cut into two pieces. After that, since the outer diameter is different between the lot A and the lot B, the control device instructs the sizer to change the interval between the sizer rolls and roll the product into the lot A product and the lot B product. In this case, the material B for the B lot may be rolled into one piece having a double length and then cut into two pieces to obtain a product. In particular, when there is a restriction on the length at the time of rolling, it is also possible to perform assembling rolling of several pieces as described above and cut the product length after rolling.
[0014]
On the other hand, conventionally, since the product length is 6 m in the case of the order lot A, as shown in FIG. Since the length is 5 m, as shown in FIG. 1C, three pieces were manufactured at a time from the lower limit length of the material constraint.
[0015]
That is, when the order lot A and the order lot B are manufactured by the conventional method, of the products manufactured from different materials, two pieces are excess in the order lot A and one piece is excess in the order lot B. In the case where a product that has been a product is manufactured by combining the order lot A and the order lot B on the same material according to the method of the present invention, there is no surplus product, and the product yield is improved.
[0016]
【The invention's effect】
As described above, in the method for manufacturing a seamless steel pipe according to the present invention, even for products having different dimensions, the same material is aggregated for each material to secure a material length equal to or greater than the material constraint lower limit length, and this material is used. after heating and transport, the control unit disconnects instructs the required length to the cutting machine, then, the control device spacing sizer roll the sizer so that each material taken is a predetermined product dimensions Since the rolling is instructed in accordance with the change, it is possible to prevent the production of a surplus product as much as possible, and to improve the product yield.
[Brief description of the drawings]
1 (a) is an explanatory diagram for manufacturing order lots A and B according to the method of the present invention, FIG. 1 (b) is an explanatory diagram for manufacturing order lots A by a conventional method, and FIG. It is explanatory drawing in the case of manufacturing order lot B.
[Explanation of symbols]
A Material for A lot B Material for B lot

Claims (1)

A seamless steel pipe is manufactured on a production line provided with a rolling mill capable of adjusting the product size according to an instruction from the control device, and a cutting machine that cuts a material after heating is arranged downstream of the heating furnace according to the instruction from the control device. The method
Even products are aggregated for each same material to ensure material constraints limit the length over the material length, after heating and conveying this material, the controller required length cutter of different sizes cut instructs, then the controller method of producing a seamless steel pipe, characterized in that each material was cut and rolled instructs the sizer to the interval changes sizer roll so as to have a predetermined product size .

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