JP3061341B2 - Cutting method of continuous cast slab - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the cutting of continuous cast metal slabs by means of an abrasive water jet.

[0002]

2. Description of the Related Art Conventionally, a billet is cut by an oxygen torch for continuous casting.

However, in the cutting by fusing, if center segregation is present in the cast structure, the heat input becomes large and the center cracks on the cut surface due to thermal strain and the like, and casting burrs such as burrs adhere to the cut portion. However, it is known that there is a problem that the removal operation is required.

However, when cutting a thick slab in continuous casting, there is no alternative means capable of high-speed cutting that can follow the moving speed of the slab which requires a cutting speed of 300 mm / min or more. At the present time, the fusing method using an oxygen torch is applied at present.

On the other hand, in recent years, a so-called abrasive water jet processing method has been developed in which an abrasive is mixed with a high-pressure jet water stream, and the abrasive is collided with a material to be cut in an accelerated state to cut the abrasive. Published Patent Publication Sho 63
JP-A-501489 discloses that this abrasive is added to a high-pressure jet stream in a pressurized state. By adding this abrasive under pressure, a large amount of abrasive can be ejected simultaneously. The cutting ability by the abrasive water jet was improved in each step.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to find out the optimum conditions for applying such an abrasive water jet cutting to the cutting of a continuous cast piece.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an abrasive having an abrasive size of 80 mesh or more is pressurized in a high-pressure jet stream in which the pressure of a high-pressure fluid source of an abrasive transport medium is 300 kgf / cm ² or more. In the cutting of a slab during continuous casting by an abrasive water jet that is added and mixed in a state, the ratio of the abrasive supplied to the high-pressure jet stream by the carrier pressurized fluid to the high-pressure jet stream is 0.1 to 2.0. It is characterized by setting.

When the present invention is applied to cutting of a continuous cast slab by the abrasive water jet, it can be efficiently applied by incorporating a circulation system for collecting and reusing the abrasive.

[0009]

In order to make this abrasive water jet correspond to the moving speed of the continuous casting slab, the pressure of the high-pressure fluid source of the abrasive medium is set to 300 kgf / cm ² or more, and the starting force source The capacity should be 75 kW or more,
In order to increase the processing ability, the abrasive should preferably have a larger abrasive grain size, and must be subjected to a condition of 80 mesh or more.

In the cutting under these conditions, if the supply weight ratio of the abrasive to the discharge amount of the carrier fluid is less than 0.1, the casting speed is 0.2 m for a slab having a thickness of about 50 to 350 mm.
The cutting ability cannot be maintained in accordance with the movement in the state of / min or more. On the other hand, if it exceeds 2.0, the cutting ability is reduced, the abrasive material is lost, and the nozzle is worn, resulting in inconvenience.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has a size of 250 × 980 mm in thickness.
An example in which the present invention is applied to cutting of a continuously cast slab at a casting speed of 1.4 m / min will be described.

FIG. 1 shows an abrasive water jet cutting apparatus 1 according to the present invention in a continuous casting apparatus, together with an abrasive continuous collection apparatus 2 and a reuse apparatus 3.
The molten steel injected from the ladle 4 through the tundish 5 into the mold 6 passes through the secondary cooling zone 7, enters the straightening roll 8 into the transport zone 9, and is cut by the cutting device 1. The abrasive used for cutting the slab is supplied again to the high-pressure jet stream at the injection nozzle 10 through the continuous recovery device 2 and the reuse device 3.

Further, the recovery device 2 and the reuse device 3 are shown in FIG.
As shown in (b), it comprises a recovery hopper, a conveyor, a three-stage sieve and a medium-size recovery hopper, a drying device, a water jet, and an abrasive hopper.

Table 1 shows that the above-mentioned continuous casting apparatus was equipped with a low-carbon steel material, an aluminum alloy containing 50% Al, and Ti40.
The following shows the application conditions of the abrasive water jet when applied to a titanium alloy having a composition of 50% or more and a copper alloy having a composition of 50% copper. In any case, the pressure of the high-pressure fluid source of the transport medium is set to 300 kgf / cm ² or more, the capacity of the starting force source is 450 kw, and the water pressure of the high-pressure jet flow is 3000
and kgf / cm ^2, was performed in a pressurized condition conveyed naturally aspirated and 3 kg / cm ² for the supply of the abrasive.

[0015]

[Table 1] FIG. 2 shows the relationship between the abrasive supply ratio to the high-pressure jet stream for each material under the above conditions and the cutting speed represented by the type of abrasive.

FIG. 2 shows the relationship between the abrasive supply ratio and the cutting speed in each embodiment.
Indicates that the above is essential.

From the above results, the following can be said.

In each of the examples, cutting was possible in accordance with the casting speed, and there was no opening at the center crack of the slab, and there was no burrs or return on the cut surface. In particular, in the cutting of the hot slab after continuous casting, the cut portion was cooled and shrunk, and the opening due to thermal strain in the segregated portion and the center crack portion could be reliably suppressed.

However, if the ratio of the amount of the abrasive supplied to the amount of the carrier fluid discharged exceeds 2.0, the cutting ability is reduced, and the loss of the abrasive increases sharply.

Further, the abrasive used for cutting was re-used by classifying the cutting powder and the abrasive in the continuous recovery device 2. This allowed 95% of the used abrasives to be recycled.

[0021]

According to the present invention, the following effects can be obtained.

(1) At the time of cutting, there is no thermal influence on the cast slab and the cut surface is finely finished, so that reprocessing after cutting is not necessary, and the cutting efficiency is remarkably improved.

(2) Since the cutting ability is excellent, a cutting step directly connected to high-speed casting can be performed, and the steps from continuous casting to rolling are completely continuous.

(3) The cracks or segregation in the central portion, which is a unique problem of the continuous cast slab, can be prevented from opening at the time of cutting and oxidizing the inside and causing defects, thereby improving the product yield.

(4) Since there is no fusing loss at the time of cutting the slab, there is no cutting loss and the slab yield is improved.

[Brief description of the drawings]

FIG. 1 (a) shows an outline of an example of equipment for carrying out the present invention. (B) shows a system in which an abrasive is collected and a reuse device is installed.

FIG. 2 shows a required supply rate of an abrasive when the present invention is applied to continuous casting of various metals.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Abrasive water jet cutting device 2 Abrasive recovery device 3 Recycling device 4 Ladle 5 Tundish 6 Mold 7 Secondary cooling area 8 Straightening roll 9 Transfer area 10 Injection nozzle

Continued on the front page (72) Inventor Kazumi Daitoku 1-1, Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Yawata Works (72) Inventor Fujiya Nogami Tobihata, Tobata-ku, Kitakyushu-shi, Fukuoka 1-1, Nippon Steel Corporation Yawata Works (72) Inventor Hiroyuki Matsumura 3-1-1, Higashikawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd.Kobe Plant (72) Inventor Yoshikazu Ikemoto Kobe 3-1-1 Higashi-Kawasaki-cho, Chuo-ku, Kawasaki-shi Kobe Plant, Kawasaki Heavy Industries, Ltd. (72) Inventor Koji Tsujida 3-1-1 Higashi-Kawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd. Kobe Plant (72) Inventor Hidenaka Tanaka 3-1-1 Higashi Kawasaki-cho, Chuo-ku, Kobe Kawasaki Heavy Industries, Ltd. Kobe Factory (56) References JP-A-1-159173 (JP, A) JP-A-62-193799 (JP, A) Hei 1-135477 (JP, A) JP Hei 4-44846 (JP, A) JP Hei 6-126622 (JP, A) JP JP-A-3-111172 (JP, A) JP-A-3-111173 (JP, A) JP-A-5-169130 (JP, A) JP-A-6-198398 (JP, A) JP-A-61-38762 (JP) , A) Special table 63-501489 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/126 B24C 5/02

Claims (1)

(57) [Claims] 1. A continuous abrasive water jet in which an abrasive having an abrasive size of 80 mesh or more is added to and mixed with a high-pressure jet flow in which the pressure of a high-pressure fluid source of an abrasive transport medium is 300 kgf / cm ² or more. A method for cutting a continuous cast slab, wherein the ratio of the abrasive supplied to the high-pressure jet stream by the carrier pressurized fluid to the high-pressure jet stream is set to 0.1 to 2.0 in cutting the slab during casting.