JPS6383228A - Heating method and heating furnace for hot rolling line - Google Patents

Abstract

PURPOSE:To execute heating with high thermal efficiency by making one-row operation of a heating furnace if the treating capacity of a rolling stage in succession to a heating stage is enough to be covered by one row of the heating furnace and conversely, making two-row operation of the heating furnaces if the treating capacity of the rolling line is higher. CONSTITUTION:The operation is made by using only one row of the heating furnace 3 or 4 and the unused row is put out to reduce energy consumption in the case of treating the ingots having small heating load in the heating furnace T. On the other hand, the two rows of the heating furnaces 3, 4 are used so that the treating capacity meets the treating capacity of the rolling stage if the ingots (CCR materials) and high-temp. heat retaining materials, etc., loaded into the heating furnace T after cooling have the large heating load. The materials having the larger heating load are charged in precedence to the other row and are preheated while the materials having the smaller heating load are treated in one load at the time of changing the operation from one-row to two-row operation. The waiting for materials to be heated in the rolling stage is thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heating method and a heating furnace in a hot rolling line.

(Conventional technology) Modern steel mills aim to save energy, save labor, and increase efficiency by making each process continuous, and the line from continuous casting to hot rolling is no exception. The 2-in hot-rolling line is directly connected to utilize the sensible heat of the slab during the casting process to reduce energy consumption in the heating furnace of the hot-rolling line. In this case, the conventional heating furnace for the hot rolling line is generally used as is.

(Problems to be Solved by the Invention) However, in the current state of the art, it is difficult to charge all slabs into a heating furnace at high temperatures due to restrictions such as surface flaws and internal quality of slabs. (hereinafter referred to as HCR) is impossible,
Some of the slabs are charged into the heating furnace after cooling as before (hereinafter referred to as CC).
R). In addition, in the heating furnace of the hot rolling line, in addition to raising the temperature of the slab for the purpose of reducing deformation resistance, it is also used for long periods of time at high temperatures for processing such as solid solution of alloying elements and diffusion of impurity elements. Heat retention may be required. For these reasons, the heating capacity required of the heating furnace differs greatly depending on the slab, and this causes a mismatch in processing capacity with the rolling process, which has a relatively stable processing time, resulting in the following losses. First, if the processing capacity of the heating process is lower than that of the rolling process, the processing capacity of the entire hot rolling line will be limited by the heating capacity, resulting in an opportunity loss; conversely, the processing capacity of the heating process is lower than that of the rolling process. If the heating temperature is high, the heated slab will remain in the heating furnace unnecessarily, and during that time, the furnace zone will dissipate,
Energy is wasted due to waste gas sensible heat loss, etc. Furthermore, when processing materials with a large heating load after processing materials with a small heating load, setting the furnace temperature to match the material with a large heating load will cause the material with a small heating load to be overcooked, resulting in energy loss. In addition, quality is likely to be adversely affected, and if the furnace temperature is lowered to avoid this, the baking of materials that require a large heating load will be delayed, resulting in material waiting in the rolling process. In order to solve this problem, it is possible to vary the processing capacity of the heating process by installing multiple furnaces in parallel, but this requires high equipment costs and a large space. . Furthermore, when a large number of small furnaces are installed, the ratio of the furnace length area to the furnace volume increases, resulting in a decrease in thermal efficiency. As an example of solving these problems, there is a proposal in Japanese Unexamined Patent Publication No. 52-73110. this is,
Using a heating furnace with two rows of heating zones, billets are sequentially charged from one row until it is full, and then sequentially charged to the other row. Once the temperature is reached, one zone is continuously rolled at once, but the time it takes to fill the zone becomes an opportunity loss, and the energy saving effect is not necessarily great.

(Means for Solving the Problems) The present invention solves the above-mentioned drawbacks, and its gist is (1) In the heating process of the hot rolling line, a heating furnace extending in the direction of conveyance of the rolled material is used. The heating furnace is divided into two rows of heating zones, and when the processing capacity of the rolling process following the heating process can be covered by one row of the heating furnaces, the heating furnace is operated in one row, and the rolling line has a high capacity and the heating furnace - A heating method for a hot rolling line, characterized in that the heating furnace is operated in two rows when the heating capacity is insufficient in row operation.

(2) A partition wall extending in the length direction of the furnace is provided at the center of the width of the furnace to form two rows of independent heating zones, and a movable hearth that moves independently is provided in each heating zone. This is a heating furnace in a hot rolling line.

(Function) The first invention divides the width of the heating zone of the heating furnace into two in the furnace length direction, and adjusts the heating load according to the temperature of the slab. By using a bisected heating zone for single-row operation and double-row operation, the discrepancy in processing capacity between the heating process and rolling process can be resolved, and the equipment cost can be lowered, while heat loss can be reduced in a small space. The second invention is a furnace that performs heating suitable for the above-mentioned heating method.

(Example) The present invention will be described in detail below with reference to the accompanying drawings showing one example thereof.

FIG. 2 shows a cross-sectional front view of a heating furnace (walking beam type heating furnace) T used in an embodiment of the present invention. The rolled material W is placed between the casting process) and the R process (rolling process), and is placed on a conveyance roller and conveyed from the C0C process.
is charged into each zone 3, 4 of the heating furnace T by a busher P, while being extracted by a moving beam 9 and conveyed to the R process.

In the drawing, 1 is a furnace shell, and a partition wall 2 made of bricks is provided in the center direction of the furnace width, extending from the furnace charging side to the furnace extraction side, and is divided into two heating zones 3 and 4 in the furnace length direction. Separate inlets 3 & 14 on the charging and extraction sides of both heating zones 3, 4;
Outlets 3b and 4b are provided. In each of the heating zones 3, 4, a fixed beam 7.7 is arranged extending in the furnace length direction by fixed columns 6, 6 at a position slightly closer to the center of the hearth 5, and a fixed beam 7.7 is provided at a position slightly closer to the center of the hearth 5. The moving beams 9,9 are arranged extending in the longitudinal direction of the furnace 1 by means of moving columns 8,8 penetrating the floor 5, and by means of an independent drive means 11 driving an eccentric wheel 11& by means of a motor 11b via a supporting frame 10. The movable beam 9 is moved up and down, and the material W (workpiece to be rolled) is alternately placed on the fixed beam 7 and the movable beam 9 while being conveyed through the furnace. Furthermore, in order to heat the front and back sides of the material W, axial flow burners 2.13 are provided above and below the material passing surface, and the heating zone 3.4 is configured to be able to individually adjust the temperature (heating - heat retention switching) in the furnace length direction. are doing. Note that the partition wall 2 may be a hollow partition wall in order to achieve a heat insulating effect.

When processing HCR materials with a small heating load, the heating furnace T is operated using only one row of heating zones 3 or 4, and the unused rows are extinguished to reduce energy consumption. When processing slabs with a large heating load such as steel sheets, Todoro CCR materials, and high-temperature heat insulating materials, two rows of heating zones 3 and 4 are used together to match the processing capacity to the processing capacity of the rolling process. In addition, when changing from -row operation to double-row operation, material with a small heating load is processed in one row, while material with a large heating load is charged in advance into the other rows and preheated, thereby reducing the baking of the material in the rolling process. It is possible to prevent waiting time.

In the embodiments of the present invention, a walking beam furnace with heating on both upper and lower sides has been described, but it can also be applied to a walking hearth furnace with a heating on the upper side of a brick hearth.

(Effects of the Invention) As is clear from the above description, according to the present invention, the equipment cost is lower than when a plurality of heating furnaces are installed, and the space is also reduced, allowing efficient heat treatment. Furthermore, since the furnace temperature can be adjusted in accordance with the internal state of the heating zone, which is divided into two by providing a partition wall, thermal efficiency is excellent and running costs are reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the entire continuous hot rolling line according to an embodiment of the present invention, and FIG. 2 is a cross-sectional front view of an embodiment heating furnace used in the continuous hot rolling line of the same embodiment. . T... Heating furnace 2... Partition wall 3m, 4m.
... Entrance 3b, 4b... Outer lower... Fixed beam 9... Moving beam 11... Drive means
12.13... Axial flow burner. Figure 1 Figure 2 Figure 2: Partition walls 3a, 4a: Entrance 3b, 4b/Exit A Fixed beam 9: Moving beam

Claims (1)

[Scope of Claims] 1. The heating process of the hot rolling line is divided into two rows of heating zones extending in the direction of conveyance of the rolled material, and if the processing capacity of the heating process ≧ the processing capacity of the rolling process, A heating method in a hot rolling line, characterized in that the heating furnace is operated with one row of heating zones, and when the throughput of the rolling process is greater than the throughput of the heating process, the heating furnace is operated with two rows of heating zones. 2. A hot rolling product characterized in that a partition wall extending in the furnace length direction is provided at the center of the furnace width to form two rows of independent heating zones, and each heating zone is provided with a movable hearth that moves independently. Heating furnace for line.