JPS58224044A - Continuous casting method of hollow round steel - Google Patents

Abstract

PURPOSE:To obtain a hollow round steel having no limits in length and having an excellent characteristic of the inside surface by inserting a steel pipe, which is produced continuously above a mold, into the mold and using the same as a core. CONSTITUTION:A steel pipe 4 to serve as a core is produced continuously above a mold 3. While such pipe 4 is inserted continuously into the central part of the mold 3, the molten steel 2 in a tundish 1 is charged between the steel 4 and the mold wall. The inside surface of the steel pipe 4 inserted into the mold 3 in this stage is cooled by feeding water or air. The cast steel and the pipe 4 are drawn in one body. The hollow round steel having the excellent characteristic on the inside surface is obtained without any limit in the length.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hollow round steel used for seamless steel pipes, raw pipes for seamless steel pipes, etc. by continuous casting.

Methods for producing seamless steel pipes include an inclined rolling method using a Mannesmann plug mill, a Mannesmann mandrel mill, etc., and a hot extrusion method including the Eugene-Séjournet method and the Bush and Pliers method.

Among these, the Eugene Selgenet method is applied to materials that are difficult to process, such as stainless steel and high alloy steel.

However, in these conventional methods, a steel ingot produced by an ingot-forming method or a continuous casting method is rolled into a hollow round steel used as a material for round seamless steel pipes, and this is then hot extruded. In this more conventional manufacturing method, the cost and yield loss of rolling and drilling the round steel are major factors contributing to the high cost.

The present invention utilizes the conventional rolling process and perforation of steel ingots by directly manufacturing hollow round steel, which is the raw material for hot extruding and manufacturing seamless steel pipes using the Eugene Séjournet method, using a continuous casting method. Skip the process and reduce manufacturing costs
] and to directly manufacture seamless steel pipes using a continuous casting method.

Many continuous casting methods for hollow round steel or metal tubes have been proposed. The main manufacturing methods can be summarized into the following four points.

■ A fixed water-cooled core casting method in which a core is placed in the center of a mold, the core is water-cooled, molten steel is injected between the mold and the water-cooled core, and the cast steel is drawn out.

(Special Public Interest Publication No. 47-34579. Special Public Interest Publication No. 47-34581
)■ A fixed graphite core casting method in which a graphite core is attached to the center of the mold, molten steel is injected between the mold and the graphite core, and the cast steel is pulled out.

■ A core is molded from a refractory material such as thermosetting shell mold sand, the sand mold core is continuously inserted into the mold, and molten steel is injected between the mold and the sand mold core to perform casting. A cast-in type sand mold core casting method in which the cast steel and sand mold core are pulled out as one unit.

(Special Publication No. 47-36615, Special Publication No. 48-5412) ■ A steel pipe of a certain length is used as a core, the steel pipe core is inserted into the center of the mold, and a hole is inserted between the mold and the steel pipe core.
k B , l L 1 fA 'a [,・1 pa°“1
A cast-in type steel pipe core casting method that produces hollow round steel tubes one by one by drawing them out in 1-by-1 steps. (Tokuko Showa 49-3
1'621) However, these casting methods have the following drawbacks.

In the fixed water-cooled core casting method (2), the molten steel in contact with the water-cooled core is cooled to form a solidified shell, which tightens the water-cooled core through solidification contraction, and the solidified shell is drawn downward. Because of the fracture phenomenon, the surface quality of the inner surface of the cast steel is poor and may even lead to the discontinuation of casting.

The fixed graphite core casting method described in (2), in addition to the condensation of the coagulation shell on the graphite core and the occurrence of solidification/el breakage phenomena, as with the water-cooled core, the cooling effect is weaker than that of the water-cooled core, and the casting speed is lower. It is easy to break due to the lack of strength of the graphite core.

The cast-in type sand mold core casting method described in (2) does not have the drawbacks of (2) and (3) above because the core is continuously supplied, but since the casting steel and the sand mold core are cast as one unit, the core is continuously supplied. It is difficult to remove the particles, and there are other drawbacks such as poor inner surface properties.

The cast-in type steel pipe core casting method described in (2) cannot produce cast steel that is longer than the core length. If the steel pipe core is made longer, it is necessary to increase the height of the equipment to charge the core into the medium heat of the mold, which limits the length of the cast product, resulting in poor productivity such as a decrease in yield. There is.

The present invention is characterized in that a steel pipe of an appropriate length is continuously manufactured above the mold and inserted into the mold P to be used as a core. Alternatively, the drawbacks of the continuous casting method for metal tubes can be avoided, and hollow round steel with excellent inner surface quality can be stably manufactured without any length restriction.

The present invention will be explained in detail below.

FIG. 1 shows a side view of the main parts of an apparatus for carrying out the method of the present invention, for example a continuous casting apparatus. While continuously manufacturing the steel pipe 4 that will become the core above the mold 3,
While continuously supplying the steel pipe to the center of the mold 3 using the centering device 5, the molten steel 2 in the tundish 1 is poured into the injection pipe 1.
The cast steel and the steel pipe 4 are injected into the space between the steel pipe 4 and the mold wall through the steel pipe 2, and then the cast steel and the steel pipe 4 are pulled out as one unit. The steel pipe manufacturing method utilizes the commonly used manufacturing method of arc welded steel pipes and electric resistance welded steel pipes.The steel strip 6 is continuously unwound and shaped into a cylindrical shape using the front and rear, left and right forming rolls 9. The joints are welded using a welding machine 10 to continuously produce steel pipes, which are used as cores. In order to reduce the height of the steel pipe manufacturing equipment, it is desirable to arrange the steel strip horizontally, bend it with rollers 7, straighten it with pinch rollers 8, and then supply it.

Since the outer surface of the steel pipe 4 comes into contact with the molten steel injected into the mold 3, the surface may be melted. Therefore, when thinning the steel pipe core, insert the water injection pipe or air blowing pipe 13 into the steel pipe 4 from the copper strip joining part above the welding machine 10, and inject water or blow air 14 into the limb pipe 13 to coat the inner surface of the steel pipe 4. Cooling is desirable.

As a part of the steel is fused with the injected molten steel and solidified, a hollow round product is manufactured with no defects between the steel pipe 4" and the injected molten steel, and the inner surface of the hollow round steel. In addition, a refractory material is used as the core. However, when casting with injected molten steel, there are disadvantages such as poor cutting during fixed length gas cutting at the end of casting due to refractory materials, and wear and tear on the saw teeth during saw cutting during product processing. Removal work was extremely difficult, but since the method of the present invention uses a steel pipe for the core, gas cutting is required.

There is no problem with saw cutting. Also, the core steel pipe was not removed, part 1.
Yes, it is possible to use it. By using the same material as the injected molten steel for the steel pipe core, a hollow round steel in which the steel pipe and the injected molten steel are fused and integrated is manufactured.

Furthermore, by using high alloy steel or the like as the material of the steel pipe core, it is possible to improve the inner surface material of the hollow round steel. When using a seamless steel pipe material ζ, even if internal processing is required, boring by turning is easy. In this case, since the steel pipe is turned and removed, the material of the steel pipe can be freely selected.

4. According to the method of the present invention, a single piece of steel pipe can be continuously supplied, and thus a homogeneous steel pipe can be supplied without center shift of the joint and strength loss, compared to the method of connecting steel pipes of appropriate lengths. can.

Furthermore, it is easy to manufacture and supply steel pipes in synchronization with the casting speed.

[Brief explanation of the drawing]

FIG. 1 is a side view of the main parts of a continuous casting apparatus as an example of an apparatus for carrying out the method of the present invention. ■... Tundish, 2... Molten steel, 3... Mold, 4... Steel pipe, 5... Centering device, 6... Steel strip, 7... Loaf +, 8... Pinch roller, 9・
... Forming roll, 10... Welding machine, 12... Molten steel injection pipe, 13... Injection pipe or blower pipe, 14... Injection or blower. Agent Patent attorney Masamitsu Akizawa and 2 others 7/ba℃, 4)~5 Tsutsui 1 Figure g

Claims (2)

[Claims] (1) Continuously manufacturing steel pipes above the mold,
A hollow round steel, which is inserted into the mold, is cast by continuously injecting molten steel between the steel pipe and the mold wall, and the cast steel and the steel pipe are pulled out as one unit. Continuous casting method. (2) The continuous casting method for hollow round steel according to claim 1, characterized in that the inner surface of the steel pipe inserted into the mold is cooled by water injection or air blowing.