JPS61126945A - Continuous casting method of hollow round bloom - Google Patents

Abstract

PURPOSE:To cast continuously and efficiently a hollow round bloom by using a free-cutting steel pipe as a core, casting simultaneously a molten steel to cast continuously the bloom together with said core by an insert-casting method then machining away the core thereby removing quickly the core. CONSTITUTION:The molten steel in a ladle 8 is cast through a tundish 6 and an immersion nozzle 9 into a casting mold 3. The free-cutting steel pipe is at the same time supplied as the core 2 under the tension exerted thereto by tension rolls 4 to the casting mold 3 while said pipe is welded by a core connector 5 consisting of flash butt welding machine. The continuous casting of the insert-casting method is thus executed. The billet drawn from the mold 3 by pinch rolls 7 is cut to a prescribed length by a torch 10 and the insert-cast core 2 is machined away after cooling. The hollow round bloom 1 is thus efficiently and continuously cast and the consumption of the tool for machining is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuous casting method for steel using a core casting method.

(Prior Art) Materials for hot pressing, such as materials for seamless steel pipes, are formed by a process of drilling the center of the cross section of a corner or round bloom obtained by continuously applying molten steel.

For example, the 69th and 70th Nishiyama Memorial Technical Lectures [Recent Advances in Bloom Billet Continuous FI Building Technology] (Iron and Steel Institute of Japan) or Mitsubishi Heavy Industries Eden Vol. 18 No. 5.

(1981, 9), a process for directly obtaining a hollow material by a fixed water-cooled core method or a core filling method has been proposed.

In the core maigurumi method, the core is cast simultaneously with the molten steel, and after the slab is cooled, the core is turned and removed to obtain a hollow slab.

In this method, since the core is removed by turning, the turning time is a major factor affecting the productivity of this process.

In the continuous casting method of the Nakasen casting method, which is the object of this invention, there seems to be no disclosure yet regarding means for improving the efficiency when turning the center of the cross section of the bond piece after it has been removed.

(Problems to be Solved by the Invention) This invention is a continuous casting method for molten metal, such as molten steel, using a core feeding method, in which the core is removed by turning the center of the cross section of the cast slab in the axial direction. The purpose of this invention is to provide a means for improving turning efficiency and lowering the unit consumption of the cutting tool (work i4:).

(Means and effects for solving the problems) The gist of this invention is to use a free-cutting steel pipe as a core in the casting method continuous II method in which the core is introduced at the same time as the molten steel. It is in the continuation of the Hollow Maru Bloom that is characterized by this.

The present invention will be explained in detail below.

An apparatus for carrying out this invention is shown in Figure #1.

In FIG. 1, 1 is a hollow round bloom, which is a product of the process targeted by this invention. 2 is the core;
In this example it is a steel pipe.

3 is a mold, 4 is a tension roll, and a plurality of rolls hold the core 2 movably in the axial direction, and the pinch roll 7 for pulling out the hollow round bloom 1 resists the downward tensile force. It is rotated at a controlled rate to impart a tensile force to the child 2 that causes it to develop a stress below its allowable stress.

5 is a core connecting device, which in this embodiment is a 7-ratch butt welding machine for welding the core at its annular end. 6
is a tundish, which is an intermediate container for supplying the molten steel from the extraction nozzle 9 into the mold 3 through the immersion nozzle 9.

10 is a torch, which cuts the hollow round bloom product into a predetermined length.

Therefore, the present inventors have found that using a core material with excellent rigidity in this process will directly improve the efficiency of turning the center of the cross section of the slab after demolition. I realized that this is a factor that has a positive effect.

Materials used for the core (steel pipe) include lead, sulfur, and Bi.
Alternatively, free-cutting steel to which sb is added alone or in combination can be used.

(Example) Using the apparatus shown in FIG. 1, continuous bonding was performed to obtain hollow circles and blooms under dog conditions.

Steel type: 5US304 Bond type inner diameter: 210m-φ Core size: 42.7m-outer diameter
n As a result, the efficiency when turning the center of the cross section of the slab after II casting is 400 s/sin in the present invention, compared to the turning speed of 200 + ss/sin when using the conventional STG steel pipe core.
1711111 - On the other hand, the lifespan of the cutting tool has been extended by 1.5 times.

(Effects of the Invention) Since the present invention is constructed and operated as described above, it greatly improves the efficiency of removing the core after continuous feeding of the hollow bloom of the core-stuffed method.
This has the effect of lowering tool consumption.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for implementing the present invention.

Claims (1)

[Claims] (1) A continuous casting method for hollow round blooms, characterized in that a free-cutting steel pipe is used as a core in a cast-in continuous casting method in which a core is cast simultaneously with molten steel.