JPH05185129A - Rolling mill for metallic sheet - Google Patents

Abstract

PURPOSE:To roll a metallic sheet by energizing it directly to be heated and adjusting its rolling atmosphere and cooling speed. CONSTITUTION:An apparatus provided with grounded work rolls 2-1, 2-2, pinch rolls 4-1, 4-2 on the inlet side, gas or liquid injection nozzles 8-1, 8-2, 8-3, 8-4. The material 1 to be rolled is energized directly, heated and rolled with the work rolls and pinch rolls as electrodes. For instance, Ar gas and cooling water are injected respectively from an injection nozzle on the inlet side and from an injection nozzle on the outlet side to produce the metallic sheet nearly free from scale.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for directly energizing a metal plate of a material to be rolled to heat it to a predetermined temperature for rolling, and adjusting an atmosphere during rolling, a cooling rate after rolling and the like. The present invention relates to a device that can be used.

[0002]

2. Description of the Related Art In manufacturing a metal plate, for example, a steel plate, a material to be rolled is often rolled in a heated state. When performing such rolling, it is customary to heat the material to be rolled in a heating furnace in advance and then send it to a rolling mill for rolling. A technique of inductively heating and rolling a material to be rolled in a rolling line without using a heating furnace or in combination with a heating furnace is also partially used.

In the rolling of metal, it is extremely important to make the rolling temperature proper. If the rolling temperature is too low, rolling becomes difficult, or the rolling mill is overloaded,
There is a problem that a desired material cannot be obtained.

The material to be rolled heated in the heating furnace is radiated and cooled in the process of being conveyed to the rolling mill, and is brought into contact with the work rolls of the rolling mill to be deheated, so that the temperature is lowered. Normal,
Although heating is performed in anticipation of this temperature decrease, excessive temperature rise causes an increase in scale loss of the rolled material and an increase in energy cost. Not only that, even if heating is performed by predicting a temperature decrease until rolling, the rolling temperature does not always become an appropriate rolling temperature during actual rolling.

Considering the above circumstances, it is most rational to heat the material to be rolled in the rolling line and as close as possible to the rolling mill to adjust the temperature. As a method of performing such heating, induction heating and direct current heating can be considered. However, since induction heating uses high frequency, the equipment is complicated and expensive, and the heating efficiency (the efficiency of converting the electric energy to heat energy) is about
As low as 30%.

On the other hand, when the temperature of the material exceeds 1000 ° C. as in hot rolling of steel sheet, it reacts with oxygen in the atmosphere during rolling to form scales, which lowers the product yield. Gas such as nitrogen penetrates into the rolled material, resulting in deterioration of product quality. Even if the scale can be removed by pickling after rolling, an additional facility is required for that, and the work is increased.

In order to prevent the material to be rolled from coming into contact with the atmosphere during rolling, it is conceivable to cover the entire rolling line with a vacuum or an atmosphere of an inert gas, but the equipment therefor becomes enormous and it is extremely difficult. It cannot be put to practical use.

[0008]

DISCLOSURE OF THE INVENTION The inventor of the present invention has developed a device that directly heats a material to be rolled by heating it by using a pinch roll and a work roll roll of a rolling mill as an electrode. Filed a patent application (Japanese Patent Application No. 3-14291)
. By using this apparatus, the material to be rolled is heated very efficiently and accurately to a predetermined temperature. Moreover, since the material to be rolled reaches the maximum temperature in the immediate vicinity of the work roll, it is exposed to the atmosphere at a high temperature for a short time, and the above-mentioned oxidation and nitrogen absorption are small.

The present invention relates to an improvement of the apparatus of the above-mentioned prior invention, in which the atmosphere during rolling is set to a non-oxidizing atmosphere, or rapid cooling is performed after rolling so that the high-temperature rolled material is exposed to the atmosphere. It is an object of the present invention to provide a device capable of further reducing the number.

[0010]

SUMMARY OF THE INVENTION The invention is summarized by the following rolling device. It is equipped with one or more sets of pinch rolls on the inlet side of the rolling mill and connected to a power source, and a work roll incorporated in the rolling mill and grounded. A device for rolling a metal plate, comprising:

The apparatus of the present invention has a basic structure in which a metal plate as a material to be rolled is directly energized and heated, and a mechanism for cutting off the vicinity of the work roll from the atmosphere or immediately cooling the rolled metal plate is added. It has a feature.

[0012]

FIG. 1 is a side view showing an example of the device of the present invention.
FIG. 2 is a diagram schematically showing only the main part thereof. In these figures, 1 is a material to be rolled (metal plate) that is rolled while traveling in the direction of the arrow. The housing 7 of the rolling mill includes back rolls 3-1, 3-2 and work rolls 2-1, 2
-2 and are incorporated. The basic structure of the rolling mill and the mechanism for rolling down the material 1 to be rolled using the rolling mill are the same as those of the conventional rolling mill.

The shafts of the work rolls 2-1 and 2-2 of the rolling mill are
A conductive brush 6 made of, for example, a copper alloy is in contact with the brush 6, and the brush 6 is connected to a part of the housing 7 so as to be able to conduct electricity. Therefore, the potential of the work roll becomes the same as the potential of the ground.

On the inlet side (upstream side) of the rolling mill, there are pinch rolls 4-1 and 4-2, which also use the same brush,
Connected to power supply 5. Plural pairs of the pinch rolls may be installed.

Work roll entry side and exit side (downstream side)
Is a device that injects gas or liquid (eg, a nozzle)
There are 8-1, 8-2, and 8-3, 8-4. These nozzles are installed in one row or several rows so as to cover the entire width of the metal plate. The apparatus shown in FIGS. 1 and 2 is an example in which the injection nozzles are provided on both the inlet side and the outlet side, but the nozzles may be installed on only one of them.

When rolling is carried out by the above apparatus, first, brushes are brought into contact with the pinch rolls 4-1 and 4-2 to supply a direct current or an alternating current. On the other hand, the work rolls 2-1 and 2-2 are also contacted with a brush and grounded. In this state, when the rolled material 1 is passed, the current flows from the pinch roll through the rolled material-work roll-housing-ground circuit,
Joule heat is generated in the rolled material. The temperature of the material to be rolled can be freely adjusted by controlling the power supplied. For this control, it is desirable to install a temperature sensor for detecting the temperature of the material to be rolled near the work roll.

The electric resistance of the metal plate increases as the temperature rises, and the amount of Joule heat generated increases.

Moreover, since the metal plate 1 runs toward the work roll, the temperature of the metal plate 1 rises steeply as it approaches the work roll of the rolling mill, and reaches the maximum temperature at the position of the work roll. Therefore, in the case of rolling with this apparatus, the time during which the metal plate is exposed to the atmosphere at a high temperature is much shorter than in the case of rolling by heating with a normal heating furnace or induction heating apparatus.

Moreover, the above-mentioned nozzle group is provided in the device of the present invention. From the inlet nozzles 8-1 and 8-2,
For example, if argon gas (Ar gas) is jetted, the hottest position of the metal plate can be completely shielded from the atmosphere and rolled, and the undesired effects such as oxidation can be further reduced. In the roll gap, the metal plate and the roll are shielded by contact, so that the rolling is performed in a completely non-oxidized state, and hot rolling at a temperature of more than 1000 ° C. can be performed without fear of oxidation.

Furthermore, if cooling water is jetted from the exit side nozzles 8-3 and 8-4 to rapidly cool the rolled metal sheet, it is possible to prevent oxidation after exiting the work roll. The outlet nozzles 8-3 and 8-4 may be used to inject argon gas or the like. The method of jetting cooling water from the outlet nozzle to rapidly cool the rolled metal sheet can also be used for heat treatment for imparting special properties to the metal sheet.

The so-called 4 is shown in FIGS.
Although it is an ordinary rolling mill of Hi, the present invention is not limited to such a rolling mill, but a rolling mill of 2Hi or a rolling mill of 6Hi, and a so-called roll shift type rolling mill in which an intermediate roll is axially operated. Can also be applied to. It goes without saying that the rolling mill can also be applied to a multi-stage tandem rolling mill.

[0022]

Example A stainless steel (JIS SUS 304) plate was rolled using the rolling apparatus shown in FIG. The main specifications of rolling equipment and rolling conditions are as follows.

Specifications of rolling mill, etc. Work roll diameter ・ ・ ・ 100 mm Back abroll diameter ・ ・ ・ 330 mm Front tension ・ ・ ・ 5 kgf / mm ² Rear tension ・ ・ ・ 5 kgf / mm ² Maximum load ・ ・ ・100 tons Pinch roll diameter ・ ・ ・ 80 mm Distance between shaft center of work roll and pinch roll ・ ・ ・ 700 mm Material to be rolled ・ ・ ・ SUS 304 Initial (before rolling) Plate thickness ・ ・ ・ 0.25 mm (Descaled material) Product (after rolling) Thickness: 0.20 mm Width: 100 mm Temperature before heating: 20 ° C Rolling conditions: Rolling speed: 10 m / min Rolling load: 85 tons Power source: AC (Commercial frequency) 15 V, 2000 A Heating temperature: 1150 ° C (Inlet side) Injection device Four jet nozzles were arranged in the plate width direction on the inlet and outlet sides at a distance of 50 mm from the work roll. The injectors were arranged in one row each above and below.

As shown in Table 1, Ar from these nozzles
The scale thickness of the rolled sheet was measured with and without the injection of gas or water.
The results are shown in Table 1. The conditions when the injection is performed are as follows.

Injection from the inlet nozzle: Ar gas (pressure:
5kgf / cm ² , flow rate: 10 liters / minute) Water jet from outlet nozzle: water (pressure: 2.5kgf / cm ² , flow rate: 5 liters / minute)

[0026]

[Table 1]

Test No. 1 in Table 1 is a comparative example in which injection was not performed on the inlet side or the outlet side. The outlet temperature of the plate at this time is
At 1050 ° C, the scale thickness is 5.2 μm. No. 2 is an example in which only Ar gas was injected on the inlet side, and the outlet temperature of the plate at this time is the same as No. 1 because the cooling is the same air cooling as No. 1. However, as a result of being shielded before rolling, the scale thickness is reduced to 3.1 μm. No. 3 is an example in which only water is injected on the exit side. The temperature of the plate after this injection is 120
The thickness of the scale has decreased to 0.7 μm.

No. 4 is an example in which Ar gas injection on the inlet side and water injection on the outlet side are used together. The thickness of the scale is reduced below the measurement error.

[0029]

The apparatus of the present invention can effectively shut off the atmosphere in the rolling section with a relatively simple structure. According to this apparatus, the metal plate can be efficiently and accurately heated to hot temperature while being shielded from the atmosphere to prevent oxidation and the like. Since the number is small, the scale removal after rolling is unnecessary or reduced, and the process and equipment can be simplified. Further, it is possible to prevent deterioration of the material due to absorption of nitrogen, and it is also possible to manufacture a metal plate having special mechanical properties by quenching after rolling.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a device of the present invention.

FIG. 2 is a diagram schematically showing a main part of the apparatus shown in FIG.

Claims (1)

[Claims] 1. At least one of a work roll inlet side and an outlet side, which comprises one or more sets of pinch rolls on the inlet side of the rolling mill and connected to a power source, and a work roll incorporated in the rolling mill and grounded. 1. A rolling apparatus for a metal plate, comprising: a device for injecting a gas or a liquid.