JPH0596319A - Hot-rolled thin-scale steel sheet manufacturing equipment - Google Patents

Abstract

PURPOSE:To obtain a hot rolled steel sheet having uniformly thin scale in the width direction, by realizing equal and uniform cooling to feed water and waste water after finish rolling and mixing inert gas in the cooling water. CONSTITUTION:After the hot rolled steel sheet 14 out of a hot rolling mill 12 is measured by a measuring instrument 16, it runs as it is bitten between upper and lower table rollers, is cooled by a running water cooling device 20 in the meantime and taken up by a take-up machine 24 via pinch rolls 22. The steel sheet is put in an N2 atmosphere from the hot finish rolling mill to the measuring instrument, then, cooled by the running water, then, N2 is mixed into the water, cooled and taken up by the take-up machine. Loose cooling is required to secure a property according to a kind of steel and cooling water is cooled loosely by flowing inert gas only like N2 gas to control the cooling speed as oxidation is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a hot-rolled thin scale steel sheet, and more particularly to a hot-rolled sheet equipped with a cooling apparatus for realizing uniform cooling and expansion of a cooling rate control range when producing the hot-rolled thin scale steel sheet. This is a thin-scale steel plate manufacturing device.

[0002]

2. Description of the Related Art FIG. 7 is a schematic explanatory view of a conventional hot-rolled steel sheet manufacturing apparatus, in which a steel sheet 72 exiting a hot rolling mill 70 passes through a cooling zone 76 while traveling on a table roller 74. It is cooled by a cooling means such as a water cooling nozzle 78, and then wound by a winder 82 through a pinch roll 80. A steel plate temperature and the like are measured by a measuring device 83 provided immediately after the exit side of the hot rolling mill 70, and the cooling strength is determined based on them.

According to such a conventional apparatus, the hot rolled steel sheet 72
Is exposed to the atmosphere during traveling on the table roller 74, so that oxide scale is generated on the surface of the steel sheet. Especially 900-1000 ℃
In the steel sheet rolled by, the scale is as thick as 10 μm. Further, since the tip end of the steel plate limits cooling in order to improve the sheet passing property, the scale becomes thicker.

Further, in the cooling in the cooling zone, all the cooling water flows down in the width direction of the steel sheet, so that the width end portion of the steel sheet is overcooled, so that the scale has a thick central portion and a thin end portion. Thus, in the conventional hot-rolled steel sheet manufacturing apparatus,
A thick scale of about 10 μm is generated on the surface of the steel sheet, and the cooling rate is different in the longitudinal direction and the width direction, resulting in uneven thickness, which is uniform in the width direction and less than 5 μm, preferably less than 2 μm. It could not be manufactured.

By the way, it is general that the oxide scale generated in the hot rolling is removed by a pickling treatment, but recently, the above-mentioned pickling treatment is simplified by suppressing the generation of scale itself in the hot rolling process. Various methods of producing or omitting hot-rolled steel sheets have been proposed. For example, JP-A-61-123403
In the gazette, the rolling mill exit side to the winder are covered with a cover to shut off the ambient atmosphere, and the atmosphere is filled with an inert gas or a reducing gas to form an atmosphere having an oxygen concentration of 1 vol% or less. A method of performing cooling until taking is disclosed.

However, in this method, the equipment cost is very high, and it is difficult to completely seal the equipment.
There is a safety issue and the feasibility is extremely low. In addition, JP-A-60
In Japanese Patent Publication No. 77932, a constrained immersion cooling device as shown in FIG. 8 is introduced as a conventional example. In this device, the steel plate 72 is constrained by upper and lower table rollers 86, the upper and lower table rollers 86 are covered with a cover 88, and water supply / drainage ports 90 and 92 are provided above and below these table rollers. According to this, running water can be cooled, and a certain scale suppression effect can be obtained, but there are the following problems.

(1) Since water is supplied and drained from the upper and lower portions of the table roller, the amount of flowing water changes with respect to the width of the steel plate, uneven cooling occurs in the width direction, and uneven characteristics of the steel plate easily occur. (2) The cooling control range is narrow due to water flow cooling, and moreover, rapid cooling will be performed, and after rapid cooling of the steel sheet that is to be wound at high temperature, it is passed without water at the coiling temperature to recover the temperature. There is a need. Therefore, the amount of oxide scale generated tends to increase rather.

[0008]

As described above, in the conventional apparatus, even in flowing water cooling, uniform cooling is not performed in the width direction, and the appearance of no water flow cannot be avoided. Thus, an object of the present invention is to solve the above-mentioned conventional problems and to provide an apparatus for manufacturing a hot-rolled steel sheet having a thin scale uniform in the width direction.

[0009]

The inventors of the present invention have completed the present invention by discovering the following points as a result of various development studies for solving the above problems. (1) For the production of thin scale steel sheet, it is preferable to cool with running water after finishing rolling is completed.In this case, the water supply port and the water discharge port can be made close to each other to make the water supply and drainage even, That allows uniform cooling in all directions. (2) In order to increase the cooling control range such as rapid cooling and slow cooling, it is effective to mix an inert gas in the cooling water.

According to the present invention, there is provided a roller restraint type running water cooling device provided on the outlet side of the hot rolling mill, which running water cooling device is constituted by respective steel plate guide portions provided between the table rollers. A hot rolled thin scale characterized in that a plurality of water jet nozzles are arranged at predetermined intervals in the width direction and the longitudinal direction in the steel plate guide portion, and drainage ports are provided corresponding to these water jet nozzles, respectively. It is a steel plate manufacturing apparatus.

According to a preferred embodiment of the present invention, a plurality of inert gas injection nozzles are arranged at predetermined intervals in the width direction and the longitudinal direction in the steel plate guide portion, and the inert gas injection nozzles are respectively provided corresponding to these inert gas injection nozzles. An exhaust port may be provided. The flow water cooling capacity can be controlled by adjusting the supply amount of the inert gas.

[0012]

The present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic explanatory view of an apparatus 10 for manufacturing a hot-rolled thin scale steel sheet according to the present invention. In the figure, a hot-rolled steel sheet 14 exiting a hot rolling mill 12 undergoes measurement by a measuring instrument 16 and then an upper and lower table. The roller 28 is run while being bitten by the roller 28, while being cooled by a running water cooling device 20 as described later, and then wound around a winder 24 through a pinch roll 22 in the same manner as in the conventional device. In the present invention, the conventional device can be used as it is, except for this flowing water cooling device, in other words, there is no particular limitation on such a device.

In order to manufacture a thin scale steel sheet, it is necessary to lower the temperature of the steel sheet 14 immediately after finishing hot rolling to shorten the oxidation reaction time and further lower the oxygen concentration in the ambient atmosphere. Even in that case, the thickness of the scale must be constant and the formation of surface defects must be prevented.

In the present invention, a flowing water cooling device for cooling the flowing water while passing the steel sheet is used as a device that exhibits such an action. Here, a specific configuration of this running water cooling device will be described. 2 is an external view of a flowing water cooling device used in the present invention, FIG. 3 is a water supply / drainage system diagram of the flowing water cooling device shown in FIG. 2, FIG. 4 is a detailed view of the same water supply / drainage, and FIG. Nozzle detail drawing, Figure 6
Is a side seal mechanism.

FIG. 2 (a) is a partial side view of the running water cooling device 20. A series of table rollers 28 are installed on the upper and lower chocks 26, 27 supported by the chock guide 24 in a state that their side surfaces are sealed. In the illustrated example, the spacing between the upper and lower table rollers 28 can be adjusted by the hydraulic cylinder 29 as a set of three sets, and the spacing is maintained at an appropriate amount, and the tip of the steel plate 14 is The trailing ends may preferably be controlled to bite them.

Similarly, as can be seen from FIG. 2 (b) showing the plan view, upper and lower steel plate guide portions 30 and 31 are provided between the table rollers, and both side surfaces thereof are provided with upper and lower chocks as in the case of the table roller. It is sealed. As shown in the figure, the water supply nozzle 3
4, N ₂ nozzle 36 and drainage / exhaust port 38 are provided at predetermined intervals. In the illustrated example, only one steel plate guide portion is shown.

From the viewpoint of uniform cooling of the front and back surfaces, they are preferably provided symmetrically on the upper and lower steel plate guide portions 30, 31. Therefore, in the following description, only the upper steel plate guide 30 will be described, but it should be understood that the same applies to the lower steel plate guide portion 31. Note that Fig. 2 (c) is
A front view is shown, and a pit 40 is provided below, and although not shown, a device for collecting and collecting the falling water is provided. 2B is a sectional view taken along the line AA of FIG.

FIG. 3 is a water supply / drainage system diagram of the running water cooling apparatus shown in FIG. 2, in which the steel plate guide portion 30 provided between the table rollers 28 is provided with a cooling water reservoir 42, respectively. The details of the cooling water pool 42 are shown in FIG. 4, and the cooling water from the cooling water system flows from the cooling water pool 42 to the tip nozzle portion.
Although it is sprayed onto the steel plate 14 via 45, the entire strip passage is in running water, and the overflowing cooling water is collected from the drainage / exhaust ports 46 provided adjacently corresponding to each other, and the steel plate guide part is also provided. It is discharged to the outside after passing 30. Thus, the central portion and the end portions of the steel sheet can be cooled at the same cooling rate.

[0019] A same for blowing inert gas such as N ₂ N ₂ gas from the supply pipe system is in flowing water of the strip passing line through the blowing nozzles 47 provided on the steel plate guide portion 30 at predetermined intervals Be blown in. The blown N ₂ gas is an exhaust port provided corresponding to each of the blowing nozzles, and in the case of the drawing, the drain port and the exhaust port are also used
Exhaust out of the system via 46. The situation at this time is shown in Fig. 4 (b).
Partly enlarged.

The provision of the drainage port (exhaust port) "correspondingly" to the water supply port or the N ₂ gas blowing nozzle is a limitation for making the cooling capacity of the cooling water uniform in the width direction of the steel sheet. This means that the cooling water in the center of the steel plate is collected at an appropriate place so that it does not flow to the end of the steel plate. Therefore, as long as such an effect is exerted, it is not limited to a specific number of installations and arrangements,
Many modifications are possible.

The detailed structure of the injection nozzles 45, 47 used for blowing the cooling water and the inert gas is shown in FIG.
Shown in (a) and (b) respectively. In each case, the tip of each piping system constitutes the steel plate guide section
44, each nozzle 45 at the tip,
47 is screwed. Structure of cooling water jet nozzle 45,
The arrangement is sufficient as long as it is possible to secure a flowing water velocity that can maintain flowing water in the passage, and also for the gas injection nozzle 47, as long as it is possible to secure a gas flow rate that can change the cooling speed,
It is not limited to a specific structure.

FIG. 6 is a partially enlarged view of the sealing structure between the upper and lower chocks 26 and 27. The sealing plate 50 is provided upright along the longitudinal direction of the lower chock 27 and the side plate 52 of the upper chock 26.
A sealing material 54 is appropriately provided between and. This is because the running water in the passage does not overflow, and it suffices to exert a sealing effect to that extent. The operation of the preferred embodiment of the flowing water cooling device used in the present invention configured as described above will be summarized and shown below.

First of all, the cooling during the passage of the hot rolled steel sheet is
Water is discharged from a nozzle attached to the tip steel plate guide plate that constitutes the guide surface of the steel plate guide portion in the gap between the hot rolled steel sheet and the steel plate guide portion. In order to uniformly cool the hot-rolled steel sheet in the width direction, a drain port is provided in the vicinity of the nozzle of the tip steel sheet guide plate so that the cooled water can be immediately discharged from the vicinity of the nozzle.

[0024] for such cooling water may be mixed with inert gases such as N ₂ gas, and further may only N ₂ gas. As described above, the water and N ₂ supply device is appropriately configured by pipes, and water or an inert gas can be flown into the gap. The existence of this gap is optimal for controlling the flow of water and temperature, and the gap is usually set to about 3 to 50 mm. It is preferable that this gap be configured to be changeable within the above range depending on the temperature, thickness and speed of the steel sheet. Flow velocity is 1 to 20 m /
It is preferable to configure so that it can be controlled in sec.

Secondly, depending on the type of steel, there are some steels that cannot be wound up on a winder at a low temperature after being rapidly cooled in order to secure their properties. In such a case, gentle cooling is required, and cooling water and an inert gas such as N ₂ gas are caused to flow from another nozzle, and further only the inert gas is caused to perform gentle cooling to prevent oxidation. The cooling rate may be controlled while controlling the cooling rate. Both drainage and exhaust are performed from the above drainage and exhaust ports.

Incidentally, since the cooling capacity varies depending on the flow rate of the cooling water, the cooling capacity in the longitudinal direction is changed by changing the flow rate of the cooling water from each water jet nozzle stepwise along the longitudinal direction of the steel sheet. You can also

Thirdly, at the time of passing the hot-rolled steel sheet, the hot-rolled steel sheet is sandwiched by the upper and lower table rollers from the delivery side of the rolling mill, and the hydraulic cylinder is operated after the tip of the hot-rolled steel sheet has passed. When the tip of the hot-rolled steel sheet is mounted on the winder in the system of sequentially releasing the pincers, all the table rollers are released and tension is applied between the rolling mill and the winder.
The rear end portion is pinched immediately before the rear end portion passes through each table roller, and is opened sequentially after the passage. With such a configuration, a constant tension may be applied over the entire length of the steel sheet.

A hydraulic cylinder and a gap adjusting sensor may be provided between the upper and lower table rollers to control the opening / closing and pressing force to control the tension of the steel sheet. Moreover, you may further install the apparatus which opens and closes by interlocking with the appropriate position sensor which detects passage of the front-end part and rear-end part of a hot-rolled steel sheet.

As described above, the table roller sandwiches only the front end and the rear end of the hot-rolled steel sheet and comes into contact with the steel sheet, but the central portion of the steel sheet does not come into contact with the table roller, so that damage to the roller is extremely small. By providing the table roller, the plate passing property including the front end portion and the rear end portion is improved as compared with the conventional case. Next, the present invention will be described more specifically by way of examples.

[0030]

【Example】

Example 1 With a conventional hot rolling mill, the inlet side thickness is 40 mm, the inlet side temperature is 1050 ° C.
The finished product was finished with a finishing mill at a delivery side thickness of 2.5 mm × width of 1200 mm and a delivery side temperature of 900 ° C, and was wound at 650 ° C. The strip running speed at the exit side of the finish rolling mill was 600 m / min.

(Example of the present invention) In the example of the present invention, the apparatus of FIG. 1 was used to set the N ₂ atmosphere from the hot finish rolling mill to the measuring instrument, and then the flow rate from 900 ° C. to 700 ° C. for 15 m was 5 m. / se
Cool with running water of c, then N _{2 in the} water at a flow rate of 1.5 m / sec
The mixture was mixed with the above, cooled to 650 ° C, and wound by a nearby winder.

(Conventional example 1) In this conventional example, the apparatus using the water spray of FIG. 7 was used. The cooling capacity was low due to the spray cooling device, and it was possible to cool to 650 ° C in about 100 m. After that, it ran in the air and was wound up by a winder in the distance. At this time, it was 180 m to the remote winder.

(Conventional example 2) In this conventional example, the apparatus of the system of FIG. 8 was used. With this device, 650 with running water of about 20 m
It could be rapidly cooled to ℃, and then it was run idle and wound by a nearby winder.

Example 2 In a conventional hot rolling mill, the inlet side thickness was 40 mm and the inlet side temperature was 1050 ° C.
The finished product was finished with a finishing mill at a delivery thickness of 2.5 mm × width of 1200 mm and a delivery temperature of 900 ° C, and was wound at 550 ° C. The strip running speed was 600 m / min except in the case of Conventional Example 1 below.

[0035] In (Embodiment) The present invention example, using the apparatus of FIG. 1, from the rolling mill to the instrument to an N ₂ atmosphere, then 25
It was cooled with running water at a flow rate of 6 m / sec from 900 ° C. to 550 ° C. over a distance of m, then passed through an N ₂ atmosphere and wound by a nearby winder.

(Conventional Example 1) In this conventional example, the apparatus using the water spray shown in FIG. 7 was used. With this method, the cooling capacity is low, so the stripping speed is reduced to 400 m / min,
It was cooled to 550 ° C. and wound on a remote winder.

(Conventional Example 2) In this conventional example, the apparatus of the system shown in FIG. 8 was used. With this device, it is possible to run 55 minutes with running water.
It could be rapidly cooled to 0 ° C, and then it was run idle and wound by a nearby winder. In the example of the present invention in Example 2, the sheet passing speed was 600 m / min over the entire length, and tension was applied by the upper and lower table rollers at the leading end and the rear end, and when the tension was applied between the rolling mill and the winder, the upper and lower tables were applied. The roller went open.

Further, in Conventional Example 1, in order to improve the sheet passing property at the tip end, cooling was restricted, the speed was made to travel up to the winder at 200 m / min, and then the speed was increased to a predetermined speed. Also, the tip
No tension could be applied to the rear end. In Conventional Example 2, the strip passing speed was 600 m / min as in the case of the present invention, but the upper and lower table rollers sandwiched the strip through the entire length of the strip. With respect to the hot-rolled steel sheets obtained in Examples 1 and 2, the scale thickness, the presence or absence of flaws, and the life of the table roller were evaluated. The above results are summarized in Table 1.

[0039]

[Table 1]

(Note) Steel plate flaw- ○: Good, △: Indentation flaw,
×: Slip defect, width shrinkage Table roller life − ○: Good wear with little wear, △: Medium wear defect, ×: Large wear defect

[0041]

EFFECTS OF THE INVENTION According to the present invention, a thin-scale hot rolled steel sheet having uniform properties can be manufactured, and further, the flaw of the steel sheet by a table roller or the like and the shrinkage of the width at the front and rear ends due to the application of tension are eliminated. Is very effective.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an apparatus for producing a hot-rolled thin scale steel sheet according to the present invention.

FIG. 2 shows a flowing water cooling device used in the present invention,
2 (a) is a front view, FIG. 2 (b) is a plan view, and FIG.
(c) is a side view.

FIG. 3 is a system diagram of water supply / drainage of a flowing water cooling device used in the present invention.

FIG. 4 is a detailed explanatory view of water supply / drainage of the running water cooling device used in the present invention, FIG. 4 (a) is a side view, and FIG.
Is a front view.

FIG. 5 is a detailed explanatory view of water supply / air supply of running water cooling water used in the present invention, FIG. 5 (a) is an explanatory view of a water supply nozzle, and FIG. 5 (b) is an explanatory view of an air supply nozzle. is there.

FIG. 6 is an explanatory view of a side seal mechanism of the flowing water cooling device used in the present invention.

FIG. 7 is a schematic explanatory view of a conventional hot-rolled steel sheet manufacturing apparatus.

FIG. 8 is a schematic explanatory view of a constrained immersion cooling device (Japanese Patent Laid-Open No. 60-77932).

[Explanation of symbols]

10: Hot-rolled steel sheet manufacturing equipment 12: Hot-rolling mill 14: Hot-rolled steel sheet 16: Measuring equipment 20: Flow cooling device 28: Table roller 30,31: Steel sheet guide section 34,45: Water supply nozzle 36,47: N ₂ nozzles 38,46: drainage / exhaust outlet

Claims (2)

[Claims] 1. A roller-constrained running water cooling device provided on the exit side of a hot rolling mill, wherein the running water cooling device comprises respective steel plate guide portions provided between respective table rollers, and the steel plate guide portion Is a plurality of water jet nozzles arranged at predetermined intervals in the width direction and the longitudinal direction, and a drainage port is provided corresponding to each of these water jet nozzles. 2. A plurality of inert gas injection nozzles are arranged at predetermined intervals in the width direction and the longitudinal direction in the steel plate guide portion, and exhaust ports are provided corresponding to these inert gas injection nozzles, respectively. The apparatus for producing a hot-rolled thin scale steel sheet according to claim 1, which is characterized in that.