JP5970881B2 - Steel rolling method - Google Patents

Description

  The present invention relates to a rolling method for hot rolling a steel material.

  In the hot rolling line for steel materials, the steel material is charged into a heating furnace, the steel material heated to a predetermined temperature is extracted from the heating furnace, and this steel material is rolled in the order of a roughing mill and a finishing rolling mill in order. The product is manufactured. However, in the case of a thin steel material (hereinafter sometimes referred to as a thin material), there is also a demand for finishing rolling by directly feeding the finishing mill without performing rolling with a roughing mill. Such a thin object has a large temperature drop while being extracted from the heating furnace and conveyed to the finishing mill, and the area reduction rate per pass in the finishing mill cannot be set large. This leads to a decrease in production efficiency due to an increase in the number of times. In particular, difficult-to-process steel types, such as austenitic and martensitic stainless steels that contain free-cutting components such as sulfur, lead, selenium, etc., or heat-resistant steels that have high deformation resistance and low workability due to the inclusion of nitrogen components In the case of such difficult-to-process materials, there is a problem that an appropriate temperature range during finish rolling is narrow, it is difficult to feed the finish rolling machine while maintaining the appropriate temperature, and end cracks occur due to low temperature rolling.

  As a measure to suppress the temperature drop of the steel material described above, it is conceivable to reduce the distance between the heating furnace and the finish rolling mill, but the distance can be shortened due to equipment restrictions such as the installation of a rough rolling mill. There is a limit. In addition, it is proposed that an intermediate heating furnace is installed between the roughing mill and the finishing mill, and the steel material is reheated to a temperature suitable for rolling in the finishing mill by the intermediate heating furnace. There are problems in that reheating in the furnace takes time, production efficiency decreases, energy consumption increases, and the hot rolling line becomes longer. Although it may be possible to produce a dedicated hot rolling line consisting of a heating furnace and a finish rolling mill by omitting the rough rolling mill, it costs more to newly manufacture a dedicated hot rolling line. This causes problems such as the need to secure points and installation space.

  Therefore, the material (steel material) and the heat insulating material are heated in the same heating pattern in the heating furnace, and the heat insulating material is placed on the upper surface of the material (steel material) in the heating furnace, and the material is left on the heat insulating material. The thing which suppresses the temperature fall of material (steel material) by conveying (steel material) just before a finish rolling mill is proposed (refer patent document 1).

JP-A-6-99212

  However, there is a problem that the temperature drop of the entire material (steel material) cannot be suppressed only by placing the heat insulating material only on the upper surface of the material (steel material) as in Patent Document 1. Further, it is difficult to place a heat insulating material on the upper surface of the material (steel material) in the heating furnace or to separate the heat insulating material from the material (steel material) extracted from the heating furnace.

  Here, in the heating furnace, a roller conveyor is adopted as a conveying means. However, when the thin object is heated, the end drooped by the heating may be caught between the rollers in the roller conveyor, which may cause a conveyance failure. It is pointed out that the conditions such as the thickness of the steel material that can be hot-rolled are limited.

  That is, the present invention has been proposed to solve this problem in view of the problems inherent in the prior art, and it is possible to improve the rolling efficiency by suppressing the temperature drop of the entire steel material. It aims to provide a method.

In order to overcome the above-mentioned problems and achieve the intended purpose, the steel material rolling method according to the invention of claim 1 comprises:
A method of rolling a steel material that is rolled by conveying the steel material heated in a heating furnace to a rolling mill,
Rolling the holding chamber defined inside the container, housing the whole capable steel material removed the steel, after heating the container in front Symbol furnace, the container having been heated in the heating furnace The gist of the invention is to feed the steel material that has been transported toward the mill and taken out of the container immediately before the rolling mill to the rolling mill and to perform rolling.

According to the invention which concerns on Claim 1, the temperature fall of the whole steel materials can be suppressed, generation | occurrence | production of defects, such as an edge part crack, can be suppressed, and rolling efficiency can be improved . In addition, since the entire steel material is housed in a container and heated and transported, even if the steel material is thin, it will not cause poor transport, and the degree of freedom in conditions such as the thickness of the steel material that can be hot-rolled will increase. , Increase versatility.

In the invention which concerns on Claim 2, the steel material accommodated in the said storage chamber and a container are relatively separated and moved along a conveyance direction, From the insertion / extraction opening opened to the downstream end of the conveyance direction of this container The gist is that the steel material is extracted.
According to the second aspect of the present invention, the steel material can be easily extracted from the housing body simply by relatively moving the steel material and the housing body.

In the invention which concerns on Claim 3, in the state which controlled the movement to the conveyance direction upstream of the steel materials accommodated in the said storage chamber by the control member, by moving the said storage body to the upstream, conveyance of this container is carried out The gist is that the steel material is extracted from the insertion / removal opening opened at the downstream end in the direction.
According to the invention which concerns on Claim 3, steel material can be easily extracted from this accommodating body only by moving an accommodating body upstream.

In the invention according to claim 4, the movement of the upstream end of the steel material is restricted by the restricting member inserted into the accommodating chamber via a gap formed in the outer peripheral wall of the accommodating body and extending in the conveying direction. The summary is as follows.
According to the invention which concerns on Claim 4, the movement to the upstream of this control member can be controlled only by inserting a control member into a storage chamber from the clearance gap formed in the outer peripheral wall of a storage body.

  According to the rolling method of the steel material according to the present invention, the rolling efficiency can be improved by suppressing the temperature drop of the entire steel material.

It is the schematic of the rolling equipment with which the rolling method which concerns on an Example is implemented. It is a top view of the container used for the rolling method which concerns on an Example. It is the sectional view on the AA line of FIG. It is a schematic perspective view which fractures | ruptures and shows the container which concerns on an Example. It is a schematic process drawing of the rolling method which concerns on an Example, (a) shows the state which is heating the steel materials accommodated in the container with a heating furnace, (b) shows steel materials from the container extracted from the heating furnace. A state in which the restricting member is inserted into the container for extraction is shown, and (c) shows a state in which the steel material whose movement is restricted by the restricting member is extracted from the container by moving the container to the upstream side. It is a figure which shows the relationship between the deformation resistance ratio in various steel types, and the temperature range which can be rolled by 50% or more of drawing. It is a graph which shows the result of the experiment 1 which measured the temperature change after extracting from the heating furnace of the steel materials accommodated in the container and heated, and the steel materials heated without accommodating in the container. It is a graph which shows the result of the experiment 2 which measured the temperature change for every pass when the steel materials accommodated and heated in the container and the steel materials reheated just before the finish rolling mill were rolled with the finish rolling mill. It is the schematic which shows another Example of a container.

  Next, the steel material rolling method according to the present invention will be described below with reference to the accompanying drawings by way of preferred examples. The upstream side and the downstream side are designated by the relationship of the steel material conveyance direction (hereinafter referred to as the material conveyance direction).

  FIG. 1 is a schematic view of a rolling facility for carrying out a method for rolling a steel material according to an embodiment. A rough rolling mill 12, an intermediate heating furnace 13, and a finishing rolling mill (rolling mill) 14 are provided downstream of the heating furnace 10. Are installed in series. In the heating furnace 10, a housing body 18 containing a steel material 16 is inserted, and the steel material 16 can be heated to a predetermined temperature together with the housing body 18. As the material of the container 18, a material having higher thermal conductivity than the steel material 16 to be accommodated and capable of efficiently heating the steel material 16 accommodated during heating in the heating furnace 10 is preferable. The material of the container 18 is preferably one that does not generate a scale by heating, and examples thereof include stainless steel such as JIS SUS304, 310, and 316. In addition, a reverse rolling mill is used as the finishing mill 14 of the embodiment.

  The container 18 is a case-like structure that is long in the material conveyance direction, and as shown in FIGS. 2 to 4, a pair of receptacles that are opposed to each other at a predetermined interval in the direction intersecting the material conveyance direction. Part 20 and a connecting part 22 for connecting the upstream ends (one end in the longitudinal direction) of the receiving parts 20 and 20 in the material conveying direction, and the longitudinal direction (material conveying direction) by the receiving parts 20 and 20 and the connecting part 22. ) Is defined so as to internally define the storage chamber S. The storage chamber S is open at the downstream end of the storage body 18 in the material conveyance direction, and is configured such that the steel material 16 can be taken in and out through an insertion / removal port 19 that is the opening. In addition, the internal dimension of the storage chamber S is set according to the dimension of the steel material 16 to be stored, and is set to a dimension that can accommodate the entire steel material 16. Moreover, it is suitable for the container 18 to have a heat capacity larger than the heat capacity of the steel material 16, and the container 18 extracted from the heating furnace 10 is conveyed to the finishing mill 14 by increasing the heat capacity of the container 18. The steel material 16 can be kept at an appropriate temperature.

  As shown in FIGS. 3 and 4, the receiving portion 20 includes a side wall (outer peripheral wall) 20 a and an upper wall (outer peripheral wall) extending from the upper and lower end portions of the side wall 20 a toward the opposite receiving portion 20. It is formed in a U-shaped cross section from 20b and the lower wall (outer peripheral wall) 20c. And between the upper walls 20b and 20b which both the receiving parts 20 and 20 oppose, and between the lower walls 20c and 20c, the clearance gaps 24 and 26 which are connected to the storage chamber S and are extended in a material conveyance direction are formed. Both the upper gap 24 formed between the upper walls 20b and 20b and the lower gap 26 formed between the lower walls 20c and 20c are also opened on the downstream end side of the container 18 in the material transport direction. Further, the upper and lower gaps 24 and 26 are set to have a width dimension that allows insertion of the regulating member 34 used when the steel material 16 is extracted from the storage chamber S. On the upper surface (surface on the side of the storage chamber S) of the lower wall 20c in each receiving unit 20, a plurality of mounting units 28a each made of a round bar extending in the material transport direction are arranged spaced apart in the width direction. In the storage chamber S, the steel material 16 is mounted on the mounting portion 28.

  Roller conveyors 30 and 32 as conveying means are disposed between the heating furnace 10, the roughing mill 12, the intermediate heating furnace 13, and the finishing rolling mill 14, and the steel material 16 is accommodated by the roller conveyors 30 and 32. It is comprised so that the container 18 or the steel material 16 can be conveyed. A roller conveyor 30 as a conveying means is also arranged inside the heating furnace 10 and the intermediate heating furnace 13. The roller conveyor 32 arranged on the upstream side of the finish rolling mill 14 includes an upstream first conveyor 32a and a downstream second conveyor 32b that can be driven independently, in front of the finish rolling mill 14. The steel material 16 extraction station ST is provided on the second conveyor 32b located. Further, the lower end of the regulating member 34 extending downward from the lower gap 26 of the container 18 is supported and supported between the rollers positioned on the upstream side of the second conveyor 32b, and the upstream side of the regulating member 34 in the material conveying direction. A receiving member 36 for restricting the movement to is provided (see FIG. 3).

(Effects of Example)
Next, the operation of the rolling equipment configured as described above will be described in relation to the rolling method. In addition, although the rolling equipment of an Example is provided with the rough rolling mill 12 and the intermediate heating furnace 13, in the rolling method of an Example, the rolling in the rough rolling mill 12 and the heating in the intermediate heating furnace 13 are not performed. .

  The steel material 16 is inserted into the storage chamber S of the storage body 18 from the insertion / removal port 19 that opens to the downstream end side in the material conveyance direction, and the upstream end of the steel material 16 is in relation to the upstream ends of the upper and lower gaps 24 and 26. The regulating member 34 is accommodated with a gap in which it can be inserted (see FIG. 2). And the accommodating body 18 which accommodated the steel material 16 in the accommodating chamber S is inserted into the said heating furnace 10, and it heats, as shown to Fig.5 (a). In the heating furnace 10, the steel material 16 is heated to a temperature suitable for finish rolling, and then the container 18 is extracted while the steel material 16 is accommodated, and the container 18 conveyed by the roller conveyors 30 and 32 is removed from the roughing mill 12. And the intermediate heating furnace 13 is passed, and it is transported to the extraction station ST on the second conveyor 32b and stopped.

  In the extraction station ST, as shown in FIG. 5 (b), a regulating member 34 is inserted from above into the upstream end side of the upper and lower gaps 24, 26 in the container 18, and the regulating member 34 is inserted from the upstream end of the steel material 16. Let it face upstream. Further, the lower end of the restricting member 34 extending from the lower gap 26 is supported by the receiving member 36 as shown in FIG. 3, and the movement of the restricting member 34 to the upstream side is restricted. In this state, when the first conveyor 32a and the second conveyor 32b are driven so as to move the container 18 to the upstream side, as shown in FIG. Only the housing 18 moves upstream with respect to the steel material 16, and the steel material 16 is extracted from the insertion / removal port 19 at the downstream end of the storage chamber S. The regulating member 34 moves relatively in the upper and lower gaps 24 and 26 in the container 18. As shown in FIG. 3, the steel material 16 accommodated in the accommodation chamber S is placed on the placement portion 28 and has a small contact area with the accommodation body 18, so that the steel material 16 is extracted from the accommodation chamber S. The resistance at the time of rolling is small, and the steel material 16 is smoothly extracted. The regulating member 34 is positioned in a positioning member (not shown) while being inserted into the upper and lower gaps 24 and 26 and reliably receives the steel material 16 that is about to move upstream as the container 18 moves. The movement of the steel material 16 can be restricted.

  By moving the container 18 onto the first conveyor 32a, the entire steel material 16 extracted from the container 18 is placed on the second conveyor 32b. In this state, only the second conveyor 32 b is driven to convey the steel material 16 to the downstream side, whereby the steel material 16 is fed into the finishing mill 14 and finish-rolled by the finishing mill 14.

  In the rolling method of the embodiment, the entire steel material 16 is heated in a state of being accommodated in the container 18, and the steel material 16 is transported to just before the finishing mill 14 while being accommodated in the container 18. The steel material 16 can be fed into the finishing mill 14 while being kept at an appropriate temperature without being reheated. Therefore, end cracks can be prevented from occurring during finish rolling due to the temperature drop of the steel material 16. Moreover, the area reduction rate per pass can be set large during rolling in the finishing mill 14, and the rolling efficiency can be improved by reducing the number of passes.

  Here, the difficult-to-work material can be defined as an index of a temperature range (difference between upper limit temperature and lower limit temperature at which rolling is possible) that can be rolled at 50% or more of drawing (drawing in a greeble test). FIG. 6 shows the steel materials of various steel types when JIS 42Ni (ASTM F30) is used as a reference steel grade and the deformation resistance value when the steel material of the reference steel grade is rolled at a temperature of 900 ° C. with a drawing of 50% is set to “1”. The measurement results of rolling with a drawing of 50% or more are shown with the temperature range (rolling upper limit temperature to rolling lower limit temperature) as the horizontal axis and the ratio of the deformation resistance value of various steel grades to the deformation resistance value of the standard steel grade as the vertical axis. It is shown. From this measurement result, it can be seen that the deformation resistance value increases as the temperature range that can be rolled at a drawing of 50% or more narrows, and the processing difficulty increases. In the rolling method of the embodiment, since the width of the temperature drop of the steel material 16 from the time when it is extracted from the heating furnace 10 and sent to the finishing mill 14 can be reduced, the temperature range that can be rolled with a drawing of 50% or more is 350. Even in difficult-to-work materials having a temperature of 0 ° C. or less, they can be fed into the finishing mill 14 in an appropriate temperature range without using the intermediate heating furnace 13.

  The steel material 16 accommodated in the housing body 18 is moved upstream by the roller conveyor 32 while the regulation member 34 inserted into the housing chamber S restricts the upstream movement of the steel material 16. You can easily extract it. That is, since the steel material 16 can be extracted from the container 18 using the existing roller conveyor 32 in the rolling equipment, it is possible to cope with the equipment without major repairs.

  Moreover, since the container 18 which accommodated the whole steel material 16 in the storage chamber S is heated with the heating furnace 10, and it conveys with the steel material 16 accommodated in the container 18, even if the steel material 16 is a thin thing with thin thickness. The container 18 can prevent the end portion drooped by heating from being caught between the rollers of the roller conveyor. Thereby, the conveyance failure by a roller conveyor does not generate | occur | produce, the freedom degree of conditions, such as the thickness dimension of the steel material 16 which can be hot-rolled, becomes large, and versatility becomes high. For example, the steel material 16 having a width of 215 to 700 mm and a thickness of 2.5 to 50 mm can be applied.

  Here, according to the rolling method of the example, the roughing mill 12 and the intermediate heating furnace 13 are installed between the heating furnace 10 and the finishing mill 14, and the separation distance between the heating furnace 10 and the finishing mill 14 is Even in a long rolling facility, finish rolling can be performed by sending the steel material 16 extracted from the heating furnace 10 to the finishing mill 14 without greatly lowering the temperature. That is, the hot rolling of the steel material 16 that does not require rolling in the rough rolling mill 12 can be efficiently performed without renovating existing rolling equipment including the rough rolling mill 12 and the intermediate heating furnace 13. Further, existing rolling equipment is used for steel materials that are roughly rolled in the roughing mill 12 and need to be reheated in the intermediate heating furnace 13 before finishing rolling, and steel materials that are only subjected to finishing rolling in the finishing mill 14. Therefore, the versatility of the rolling equipment can be increased, and various types of rolling can be handled.

(Experiment 1)
Inventive Example 1 in which the steel material is JIS AMS5706 (ASTM B637) and the steel material 16 having a thickness of 14 mm, a width of 250 mm, and a length of 4200 mm (weight: about 100 Kg) is used, and the steel material 16 is accommodated in a container 18 made of JIS SUS304, and For Comparative Example 1 in which the steel material 16 is not housed in the housing 18, the steel material 16 is heated to 1200 ° C. in the heating furnace 10, and then extracted from the heating furnace 10 and left in the outside air. The results of measuring the change in surface temperature are shown in FIG. In addition, as the container 18, the outer dimensions are approximately 140 mm in height, 450 mm in width, and 6000 mm in length, and the inner dimensions are approximately 50 mm in height, 350 mm in width, and 5000 mm in length. Moreover, in the invention example 1, the temperature of the steel material 16 in the state which has accommodated the steel material 16 in the container 18 is shown. As shown in FIG. 7, the temperature change with the passage of time is moderate in Invention Example 1, whereas the temperature change with the passage of time is rapid in Comparative Example 1, and the steel material 16 is accommodated in the container 18 and heated. It was confirmed that an extremely high heat retention effect was obtained.

(Experiment 2)
About the steel material 16 of the same kind and the same size as the steel material 16 used in the experiment 1, the temperature when the steel material 16 is extracted by being heated in the heating furnace 10 while being accommodated in the container 18 made of JIS SUS304 is about 1200 ° C. Inventive Example 2 and Comparative Example 2 in which the temperature when the steel material 16 was heated and extracted in the heating furnace 10 was about 1200 ° C., the thickness was reduced to 5.8 mm in three passes in the finishing mill 14. The result of measuring the surface temperature after each pass during rolling is shown in FIG. Inventive Example 2, in which the container 18 extracted from the heating furnace 10 is passed through the roughing mill 12 and the intermediate heating furnace 13 and transported to just before the finishing mill 14, the steel material 16 extracted from the container 18 is extracted. Rolled with a finishing mill 14. In Comparative Example 2, the steel material 16 is directly charged into the heating furnace 10 and heated without using the container 18, and the steel material 16 extracted from the heating furnace 10 is subjected to intermediate heating after passing through the rough rolling mill 12. After being reheated to about 1200 ° C. in the furnace 13, it was rolled by a finishing mill 14. From the result shown in FIG. 8, the temperature change of Invention Example 2 is substantially the same as that of Comparative Example 2 reheated immediately before the finish rolling mill 14, and the steel mill 16 is accommodated in the accommodating body 18, whereby the finishing mill 14 It was confirmed that it had the same workability as the condition reheated immediately before. Further, when the steel material 16 is reheated in the intermediate heating furnace 13, the time required for the reheating takes about 8 hours, resulting in a problem that the production efficiency is lowered. However, in the invention example 2 in which the reheating is not required, the production efficiency is reduced. Can be improved.

[About another embodiment]
FIG. 9 is a schematic view showing another embodiment of the container, and the same parts and portions having the same functions as those of the embodiment are denoted by the same reference numerals and only different portions will be described. That is, the container 38 according to another embodiment connects the lower walls 20c and 20c of the receiving portions 20 and 20 without gaps, and conveys the material corresponding to the upper gap 24 to the connecting portion of the lower walls 20c and 20c. A long groove 40 extending along the direction is formed. In the container 38 of another embodiment, when the steel material 16 is extracted from the storage chamber S, only the container 18 is placed downstream with the lower end of the restriction member 34 inserted from the upper gap 24 facing the long groove 40. The steel material 16 can be extracted from the storage chamber S by moving to. Moreover, in the container 38 of another Example, since the lower side of the storage chamber S is obstruct | occluded entirely, the heat dissipation of the steel material 16 accommodated in the storage chamber S can be suppressed more, and the heat retention effect is heightened. obtain.

[Example of change]
The present invention is not limited to the configuration of the embodiment, and various modifications are possible. For example, the following configurations can be adopted.
(1) In an embodiment or another embodiment, an upper gap extending in the material transport direction is provided on the upper wall of the container, and a restriction member inserted into the storage chamber from the upper side through the upper gap to the upstream side of the steel material. Although the movement is regulated, the regulating member may be inserted into the accommodating chamber from the lower side through the lower gap, or the regulating member may be inserted into the accommodating chamber from the gap formed on the side wall. That is, the gap formed in the container so as to be connected to the storage chamber and extending in the transport direction may be formed on any of the outer peripheral walls (upper wall, lower wall, side wall) constituting the container. Good.
(2) In the embodiment or another embodiment, a clearance extending in the material conveyance direction is provided on the upper wall of the container, and the movement of the steel material to the upstream side is regulated by a regulating member inserted into the accommodation chamber from the gap. However, the container is formed in a rectangular tube shape that opens to the upstream side and the downstream side, or the upstream end has a bottomed square tube shape and a through hole is formed in the upstream end. The movement of the steel material to the upstream side may be restricted by a restriction member inserted into the storage chamber. Thus, by forming a container in the shape of a rectangular tube, the exposed portion of the steel material can be reduced to further suppress heat dissipation.
(3) In the example and other examples, the steel material was extracted by moving the container to the upstream side in a state where the movement of the steel material to the upstream side was restricted, but the state in which the container was stopped The steel member may be pushed out of the housing body by moving the regulating member inserted into the housing chamber to the downstream side. Alternatively, the steel member may be pushed out of the housing body by inserting an extrusion member into the housing chamber from an upstream opening or through hole of the housing body formed in a rectangular tube shape and moving the extrusion member to the downstream side.
(4) In the examples and other examples, the steel material is inserted / removed through the insertion / removal port formed at the downstream end in the material conveying direction of the container, but the container is formed in a box shape that can be divided vertically. Then, by removing the upper half from the lower half, the steel material may be taken into and out of the accommodation chamber from the insertion / removal opening that opens upward.

DESCRIPTION OF SYMBOLS 10 Heating furnace, 14 Finishing mill (rolling mill), 16 Steel material, 18 Container, 19 Insertion / removal port 20b Upper wall (outer peripheral wall), 24 Upper gap (gap), 34 Control member, 38 Container S Storage chamber

Claims (4)

A steel material (16) heated in a heating furnace (10) is conveyed to a rolling mill (14) and rolled.
The container (18, 38) therein image forms the housing chamber (S), said housing the entire steel (16) a removable to steel material (16), the container (18, 38) before Symbol after heating in a heating furnace (10), and transported toward the accommodating body that is heated by the heating furnace (10) and (18, 38) to the rolling mill (14), housed in the immediately preceding the rolling machine (14) A method of rolling a steel material, characterized in that the steel material (16) taken out from the body (18, 38) is fed into a rolling mill (14) for rolling.   The steel material (16) accommodated in the accommodation chamber (S) and the accommodating body (18, 38) are moved relatively apart from each other along the conveying direction, so that the accommodating body (18, 38) can be moved in the conveying direction. The steel material rolling method according to claim 1, wherein the steel material (16) is extracted from an insertion / removal opening (19) opened at the downstream end.   By moving the container (18, 38) to the upstream side in a state where the movement of the steel material (16) stored in the storage chamber (S) to the upstream side in the conveying direction is regulated by the regulating member (34). The steel material rolling method according to claim 1 or 2, wherein the steel material (16) is extracted from an insertion / removal port (19) opened at a downstream end in the conveying direction of the container (18, 38).   The regulating member (34) inserted into the accommodating chamber (S) through a gap (24) formed in the outer circumferential wall (20b) of the accommodating body (18) and extending in the conveying direction, the steel material (16 The steel material rolling method according to claim 3, wherein movement of the upstream end of the steel material is restricted.

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