JPH08206705A - Method for manufacturing thick plate and middle plate - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a highly productive manufacturing method for drastically reducing the manufacturing cost of thick plates and intermediate plates. [Structure] When manufacturing thick plates and intermediate plates by a continuous hot rolling mill or a hot rolling mill directly connected to a thin slab CC, the hot rolled steel sheets are immediately or at 300 ° C. on a runout table.
A method for producing a thick plate, which is characterized in that after cooling, the base metal of the thick medium plate, the thick plate or the medium plate is cut at high speed during the cooling. A method for producing the thick plate and the middle plate, which comprises piling the base material of the thick middle plate, the thick plate or the middle plate on a runout table at high speed while stacking them in the air with a magnet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing thick plates and intermediate plates, and more particularly to rolled steel products for general structures such as shipbuilding, construction, bridges, industrial machines, automobiles, tanks and pressure vessels, rolled steel products for welded structures, The present invention relates to running cutting of steel plates for pressure vessels, workable hot rolled steel materials for automobiles and the like.

[0002]

2. Description of the Related Art Due to the increase in imported steel materials against the backdrop of the strong yen in recent years, the demand for price reduction for thick plates and middle plates has become stronger, and it is necessary to consolidate high quality thick plates and middle plates to international prices. I'm in a situation where I can't get it. Therefore, in order to cope with the wave of price destruction, it is necessary to review the manufacturing of thick plates or intermediate plates to drastically reduce the manufacturing cost.

A hot rolled steel sheet of 3 mm or more and less than 6 mm is used as an intermediate plate,
Hot-rolled steel sheet of 6 mm or more is classified as a thick plate and may be collectively referred to as a thick medium plate. However, the production of a thick plate in a thick plate rolling mill is usually 4.5 mm or more, and sometimes 300 mm or more and 600 mm. 3 production of thick and medium plate in continuous hot rolling mill
It is manufactured by cutting with a shear line from a hot rolled coil of mm or more or an extremely thick hot rolled coil of 13 mm or more.

As a conventional method for manufacturing a thick plate and an intermediate plate, a thick plate rolling mill is used to manufacture thick plates (Steel Manual 3 (1) Rolling foundation / steel plate P221, issued in 1980) and hot rolling by a continuous hot rolling mill. Manufacturing by rewinding and cutting the coil (Steel Manual 3
(1) Rolling foundation / steel sheet P436, issued in 1980). However, the production of thick plates characterized by reverse rolling is low in productivity, the manufacturing cost is higher than that of medium-thick plates, and it is difficult to compete with imported steel except high-grade steel.

On the other hand, although the thick and medium plate obtained by cutting the hot rolled coil has a lower manufacturing cost than the thick plate produced by the thick plate rolling mill, the uncoiler for rewinding the hot rolled coil and the leveler equipment for correcting the shape This imposes restrictions on production capacity and manufacturing dimensions, and naturally limits the price of imported steel.

As a conventional piling method for thick plates, there is a method using a piling crane (edited by The Iron and Steel Institute of Japan, Second Edition (Recent Advances in Plank Manufacturing Technology in Japan) P81, published in 1984). This is used when steel sheets are taken offline from a line table to a warehouse or a refinery, transferred to another line, or stacked on a table.
In the case of stacking only on a table, there is a limitation that productivity of piling is low because the movement when stacking one steel plate on another steel plate is slow.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the problems of productivity, production capacity and dimensional constraint in the above-described thick plate and intermediate plate, and also reduces the manufacturing cost drastically. The purpose is to provide a manufacturing method.

[0008]

Means for Solving the Problems The inventors of the present invention have made a detailed study on the improvement of productivity of a thick plate or an intermediate plate, and found that the hot rolled steel sheet is manufactured by breaking the common sense that it is wound as a hot rolled coil. We have come to discover that the cost can be drastically reduced.

The method for producing a hot rolled steel sheet, which is the object of the present invention, is rapidly prevailing by means of a rough rolling mill and a continuous finishing rolling mill after reheating a conventional continuous cast slab, or by a recently developed mini mill. Any of the methods for producing a hot rolled steel sheet directly connected to the thin slab CC may be used. Further, the production of the hot rolled steel sheet is carried out by a dedicated line for producing the thick plate or the intermediate plate of the present invention
It may also be used as a combined line for manufacturing a hot rolled coil.

That is, the gist of the present invention is as follows. (1) When manufacturing a thick plate and an intermediate plate by a continuous hot rolling mill or a hot rolling mill directly connected to a thin slab CC, the hot rolled steel plate is cooled on a run-out table immediately or after cooling to 300 ° C. or less, and 400 to 1500 t / h. A method for manufacturing a thick plate and a medium plate, which comprises cutting a sheet to a length of an order after manufacturing a base material of the medium plate by performing hot cutting at. (2) When manufacturing a thick plate and an intermediate plate by a continuous hot rolling mill or a hot rolling mill directly connected to a thin slab CC, the hot rolled steel plate is cooled on a run-out table immediately or after cooling to 300 ° C. or lower, and then 400 to 1500 t / h. A method for manufacturing thick and medium plates, which is characterized by cutting while running to a custom length. (3) The thick plate according to the above (1) or (2), characterized in that after the base material of the thick medium plate, the thick plate or the medium plate is cut while running on a runout table, it is piled in the air by a magnet and piled. And a method for manufacturing an intermediate plate. Here, the base material of the thick and medium plate refers to an intermediate product including a thick plate of a custom-made length manufactured by the present invention and a cutting allowance before final cutting capable of collecting a plurality of middle plates.

[0011]

[Function] The inventors of the present invention have made a detailed study on the influence of productivity on the manufacturing cost reduction method for thick plates or medium plates, and it is most advantageous to effectively utilize the characteristics of hot-rolled steel plate with high productivity. I found that. That is, it has been found that in manufacturing a hot rolled steel sheet, by breaking the common sense of winding as a hot rolled coil, it is possible to enjoy the highest productivity and to save the process of coiling → uncoiling → leveler straightening.

The present invention will be described in detail below. The hot-rolled steel sheet targeted by the present invention is manufactured by a rough rolling mill and a continuous finish rolling mill, or by a hot rolling mill directly connected to a thin slab CC. Further, the hot rolled steel sheet is manufactured by a dedicated line for manufacturing the thick plate or the intermediate plate of the present invention, or by a combined line for manufacturing the hot rolled coil.

In the case of a dedicated line, on the run-out table on the rear surface of the finishing rolling mill, the running cutting machine → the steel plate cooling device → the magnet pillar or the steel plate cooling device → the running cutting machine → do not interfere with each other in this order. Install. On the other hand, in the case of a dual-use line, on the run-out table between the finishing rolling mill and the hot-rolled steel sheet coiler, the running cutting machine → steel plate cooling device → magnet pillar or steel plate cooling device → running cutting machine → magnet pillar Install so that they do not interfere with each other. In addition, in order to attract the steel sheets after hot cutting by a magnet pillar and to reheat after stacking, the steel sheets are cooled to 300 ° C. or lower in order to prevent aesthetic deterioration of the steel sheet surface due to defective shapes and scale.

The hot-rolled steel sheet is cut while running for each base material (order length × N + final cutting allowance) of a thick or medium plate capable of collecting a plurality of thick plates or medium plates (for example, N = 2 to 7). Or, for each ordered length of thick plate or medium plate. Considering the productivity of hot-rolled steel sheets, it is preferable to use thick-medium plate for each base metal, but in that case, it is necessary to perform final cutting to the ordering dimensions of thick- or medium-sized plates with a finishing line. From the viewpoint, it is possible to comprehensively judge and select the more advantageous one. The cutting of the thick plate or the medium plate from the base material of the thick medium plate may be performed by shearing or degassing which is commonly used for plate thickening or shearing of hot rolled coils, but laser cutting, electron beam cutting or plasma cutting with high productivity. Cutting is preferred.

A conventional method such as a mechanical type or an energy type may be used as the cross cutting machine. The running cutting speed is 400 to 1500t because it is necessary to match the productivity of hot rolled steel sheet.
/ H. As a mechanical type, for example, Japanese Patent Publication No. 6-9200
There is a high-speed type shear as shown in Japanese Patent No. 2, in which an upper blade and a lower blade intersect each other after a plurality of rotations to shear the hot-rolled steel sheet. As an energy type, there is a method of systematically tracking the length and performing electron beam cutting, plasma cutting, laser cutting, or the like in between. In this case, it is necessary to maintain the function of correcting the conveying speed of the hot-rolled steel sheet so that the cutting line is not inclined and the yield is not greatly reduced.

[0016] For stacking and piling piles of thick-middle plates or thick plates in the air by means of magnets, a piling crane or the like is arranged on a run-out table, and the thick-middle plate base materials and thick plates are cut while running. Alternatively, the intermediate plates are successively stacked in the air underneath, and line-off is performed after every fixed number of sheets (for example, N = 5 to 50) to be conveyed to the next step (storage, shipping), or they are transferred to the adjustment line table. . In this case, in order not to lose the productivity of the hot-rolled steel sheets, the purpose is to stack them in the air with a magnet and perform a piling process in a large lot. Mutual shift may be performed using a crane or the like.

[0017]

EXAMPLES Table 1 shows examples of the present invention. In the example of the present invention, a hot rolled steel sheet was manufactured by continuous hot rolling. In addition, the middle plate is cut by electron beam to the base material of thick middle plate (N = 5), and then cut to the desired length with a laser while being stacked on the adjusting line.
The slab was cut by running with an electron beam to the ordered length (N = 1). Then, after cooling to 200 ° C., they were piled up in the air by a piling crane.

[0018]

[Table 1]

The thick plate or the middle plate of the present invention is 800 to 110 without impairing the high productivity which is a characteristic of the continuous hot-rolled steel plate.
It has a high productivity of 0t / h. On the other hand, although the middle plate of the comparative example uses the hot rolled steel plate, the productivity is reduced to 1/3 of that of the present invention because the hot rolled coil is unwound and the leveler is corrected. The thickness of the thick plate is about 1/4 of the present invention.

Therefore, according to the present invention, it is possible to achieve a great improvement in productivity as well as a process saving such as coiling, rewinding and leveling of a hot rolled coil. Further, in the production of the conventional intermediate plate, there was a plate thickness constraint for rewinding the hot rolled coil, but in the method of the present invention, the plate thickness constraint is eliminated because there is no rewinding using the hot rolled steel plate, It is possible to manufacture thick plates as well as plates.

[0021]

EFFECTS OF THE INVENTION In the production of thick plates and intermediate plates according to the present invention, it is possible to reduce the capital investment cost (fixed cost) by the process saving, and at the same time, reduce the variable cost (variable cost) by significantly improving the productivity. It is possible to reduce the Therefore, according to the present invention, it is possible to solve the plate thickness constraint, improve the competitiveness in a short period of time, and improve the energy saving price competitiveness, and the economic benefits to the industry are enormous.

Claims (3)

[Claims] 1. When manufacturing thick plates and intermediate plates by a continuous hot rolling mill or a hot rolling mill directly connected to a thin slab CC, the hot rolled steel sheets are immediately or 3 times on a run-out table.
A method for producing a thick plate and a medium plate, which comprises cooling to a temperature of 00 ° C. or lower, cutting while running at 400 to 1500 t / h to manufacture a base material of a thick medium plate, and then cutting to a custom length. 2. When producing a thick plate and an intermediate plate by a continuous hot rolling mill or a hot rolling mill directly connected to a thin slab CC, the hot rolled steel sheet is immediately or 3
A method for producing a thick plate and an intermediate plate, which comprises cooling to a temperature of 00 ° C. or lower and then cutting while running to a custom length at 400 to 1500 t / h. 3. The thick plate according to claim 1 or 2, wherein the base material of the thick medium plate, the thick plate or the medium plate is cut on a run-out table during running and then piled up in the air by a magnet for piling. Manufacturing method of middle plate.