JP3406175B2 - Descaling device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a descaling technique for hot rolled steel sheets.

[0002]

2. Description of the Related Art Conventionally, in a descaling process for removing the skeleton attached to the surface of a hot rolled steel sheet, the hot rolled steel sheet is passed through a skel breaker to cause cracks in the skeleton of the surface, and then the hot rolled steel sheet is removed. By passing it through the pickling tank, the pickling solution reaches the FeO layer, which is the lowest layer of the skeleton and is easily attacked by the pickling solution, through the cracked portion, and the method of promoting peeling of the entire skelton is an industrial method. Has been done in. The striping speed of the descaling process is about 10 m / min, which is the maximum speed limit, and compared to the recent speeding up of other processes, the speeding up has slowed down and the overall speeding up bottle It has become a neck.

[0003]

In the descaling process, it is the speed of the pickling tank that limits the strip passing speed. The rate of skeleton peeling depends on the number of cracks generated in the skeletal breaker, and the larger the number of cracks, the faster the peeling. However, a skeletal breaker that has been conventionally implemented is one that passes through a plate so as to alternately sew multiple stages of rolls and uses the bending of the plate to cause cracks in the skeleton, which is technically mature. Therefore, it is considered difficult to significantly improve the crack occurrence frequency compared to the current situation. The present invention has been proposed in view of the problems of the above-described conventional techniques, and the purpose thereof is to significantly improve the frequency of cracking the skeleton without significantly changing the conventional process, and to significantly Another object is to provide a descaling device that realizes a high process speed.

[0004]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the problems of the prior art, and in a descaling device for removing skeleton on a hot-rolled steel sheet, it is provided at a stage before being carried into a skeletal breaker. The hot-rolled steel sheet is irradiated with a laser beam to give a laser irradiation mark to the skeleton.

[0005]

1 is a diagram schematically showing a descaling device of the present invention. The inventors call this device a laser perforation descaling device. The whole is composed of a laser beam 1, a skeletal breaker 2, and a pickling layer 3. The drawing shows the case where the hot-rolled steel sheet 4 is moved to perform descaling in a continuous process. The laser beam 1 is irradiated onto the hot-rolled steel plate 4 before the hot-rolled steel plate 4 is carried into the skeletal breaker 2, and perforations 5 are provided on the skeleton on the hot-rolled steel plate 4. Although FIG. 1 shows that the upper surface of the hot-rolled steel sheet 4 is irradiated with the laser beam 1, the same processing is performed on the lower surface.

FIG. 2 shows a cross section near the surface of a perforation-like irradiation mark 5 provided by the laser beam 1.
The skeleton on the hot-rolled steel sheet 4 usually has a multi-layered structure of three layers, in which the lowermost layer is FeO, then Fe ₃ O ₄ , and the uppermost layer is Fe ₂ O ₃ containing iron as a main component. It consists of physical layers. These oxides have extremely high wavelength absorption characteristics and absorb almost 100% at a wavelength of 10.6 μm of a carbon dioxide laser which is a high-power laser for industrial use. Therefore, even a laser with an energy of several mJ per pulse has a diameter of 10
By condensing light to a size of about 0 μm and irradiating it onto the skeleton, holes having a depth of 10 μm or more can be easily processed. Since the thickness of the skele that grows on the hot-rolled steel sheet between the hot rolling step and the cold rolling step is at most 8 to 10 μm, the skele must be partially completely removed even with the above small laser energy. Is possible. The removal of the skeleton by the laser beam 1 does not necessarily have to be performed in the form of continuous grooves, but discrete perforations are sufficient. The reason is due to the following mechanism.

The hot-rolled steel plate 4 having perforation-like irradiation marks 5 on the surface skeleton is subsequently passed through the skeletal breaker 2. At this time, by being bent by the skeletal breaker 2, as shown in FIG. 3, the peeling of the skeleton from the main body of the hot-rolled steel sheet 4 progresses starting from the perforation portion. By providing perforations at appropriate intervals, the skele after passing the skel breaker 2 through plate has cracks in the tatter, and is in a state of just before peeling. Further, as it is passed through the pickling tank 3, the pickling solution penetrates from these peeled parts, the FeO layer at the bottom of the skeleton is corroded by the pickling solution, and completely peeled from the hot-rolled steel sheet 4. To do. Regarding the interval of perforation imparted by the laser, an experiment was conducted using a sample plate for experiments, and if the width was 20 mm or less in both the sheet passing direction and the sheet width direction, the effect could be maintained even at high speed sheet passing of 100 m / min or more. It was confirmed.

According to the method of the present invention, the efficiency of the pickling solution infiltration is very high due to the presence of a large number of cracks, so that the time required for complete peeling of the skeleton can be greatly shortened.

[0009]

EXAMPLE Using the descaling device of the present invention, a thickness of 2
mm hot rolled steel sheet having a width of 2000 mm was descaled. The material of the steel plate is ordinary steel, and the plate passing speed is 100 m / min.
The conditions for applying laser perforation-like irradiation marks are as follows.

[Example of the present invention] Irradiation laser beam: Q-switch carbon dioxide laser intensity distribution: Donut mode average output: 3.3 kW x 1 unit Pulse energy: 100 mJ Repetition frequency: 33 kHz Focused beam diameter: 200 µm x 10 mm Laser beam scan Direction: Right angle to the sheet passing direction (sheet width direction) The perforation row application interval in the sheet passing direction was 10 mm, and the skeleton removal rate in this example was 100%.

The scanning of the laser beam in the plate width direction was performed by a polygon scanner. Therefore, the actual irradiation mark array on the plate is not perpendicular to the plate passing direction but slightly inclined, but this does not hinder the effect. The individual perforation intervals in the width direction are determined by the plate width, the perforation line spacing in the plate passing direction, and the plate passing speed. That is, the perforation line spacing in the sheet passing direction is now 1
If 0 mm and the plate passing speed are 100 mpm, the time available for scanning in the plate width direction is 6 ms. The plate width of 2000 mm is scanned within this time. Since the laser repetition frequency is 33 kHz, the number of irradiation marks provided in the plate width direction is 198. Therefore, the irradiation mark interval in the plate width direction is about 10 mm. After all, in this example, in the form of repeating diamond-shaped vertices with a side of 10 mm on one side of the board,
Perforations are added.

As a comparative example, a conventional descaling device was used to descale a hot-rolled steel sheet having a thickness of 2 mm and a width of 2000 mm. The material of the steel plate is ordinary steel, and the plate passing speed is 10 m.
/ Min.

[Comparative Example] The skeletal removal rate in this comparative example without irradiation laser beam was 95%. In the example of the present invention, the skeleton removal rate of 100% is achieved despite the passing speed which is 10 times faster than that of the comparative example. Therefore, the innovative effect of the present invention for improving productivity is clear. Let's do it.

[0014]

As is apparent from the above description, according to the present invention, the frequency of cracking to the skeleton can be significantly improved without significantly changing the conventional process, and the process speed can be significantly increased. It is possible to provide a descaling device that realizes

[Brief description of drawings]

FIG. 1 is a drawing schematically showing a laser perforation descaling device of the present invention.

FIG. 2 is a drawing schematically showing how laser perforations are applied.

FIG. 3 is a drawing schematically showing how the skeleton is peeled off starting from the laser perforations when the skeletal breaker is passed through.

[Explanation of symbols]

1 laser beam 2 skeleton breakers 3 pickling tank 4 Hot rolled steel sheet 5 Perforation provided by the laser beam

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-182020 (JP, A) JP-A-59-41482 (JP, A) JP-A-2-197588 (JP, A) JP-A-57- 56109 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B21B 45/06 C23G 3/02

Claims (4)

(57) [Claims] 1. A descaling device for passing a hot-rolled steel sheet and removing the skeleton on the hot-rolled steel sheet, by irradiating a laser beam in the width direction of the hot-rolled steel sheet at a stage before being carried into a skel breaker. , A descaling device comprising a laser irradiation device for providing perforated discrete irradiation marks on the skeleton. 2. The descaling device according to claim 1, wherein the perforation spacing of the irradiation marks is 0.1 mm or more and 20 mm.
It is below, and the irradiation mark row interval in the passing direction is 0.1 mm or more 2
A descaling device comprising a laser irradiation device of 0 mm or less . 3. The descaling device according to claim 1, wherein the laser of the laser irradiation device is a pulse laser.
Descaling device characterized by being a user. 4. A descaling device according to claim 3, descaling and wherein the record over THE is carbon dioxide laser.