JPH0144401B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a method for treating the end face of a cast slab.
More specifically, the present invention relates to a treatment method for locally heating and melting the end face of a continuously cast slab.

Center cavities (hereinafter simply referred to as cavities), which are shrinkage holes, are scattered in the center of a slab cast by a continuous casting device. When this slab is heated in a heating furnace prior to rolling, end face oxidation occurs in which oxidation and decarburization progress from the cavity exposed on the end face of the slab to the inside, so both ends of the slab are rolled to maintain quality. 80~ each after
It was necessary to cut off about 100 kg, which was uneconomical. In addition, in order to prevent this end face oxidation, attempts have been made to seal the cavity by welding the end face of the slab, locally melting it with a burner, or applying mortar paste, but in the case of hot slabs, Both methods are difficult work as they require working near the cast slab, which is at temperatures of over 1000°C, and are time-consuming even when working with cold slabs.

This invention solves the above-mentioned conventional drawbacks,
The object of the present invention is to provide a method for treating the end face of a slab, which can quickly and easily perform oxidation prevention treatment on the end face of the slab.

However, the gist of this invention is to press a thermite solid piece made by solidifying a thermite agent using a binder to the center of the end face of the cast piece,
A method for treating an end face of a cast slab, characterized in that the solid piece of thermite is heated and ignited, and the vicinity of the pressed part of the solid piece of thermite of the slab is melted by the heat of reaction of the solid piece of thermite, and then solidified. .

The thermite agent used in the present invention is a mixture of aluminum powder and a metal oxide such as iron oxide, to which is added an oxidizing agent such as sodium chlorate, a combustion improver such as cryolite, and the like. The ignition speed can be controlled by adjusting the amount of the oxidizing agent and combustion improver. Further, as the binder in this invention, an organic binder such as phenol resin is suitable, but other materials such as an inorganic binder such as sodium silicate can also be used.

An embodiment of the present invention will be explained below with reference to FIG.

20% aluminum powder (weight%, same below),
A solid piece of thermite with a diameter of 50 mm and a thickness of 20 mm is obtained by heat molding a mixture of a thermite agent and a binder with a blending ratio of 70% iron oxide (scale), 2% sodium chlorate, 4% cryolite, and 4% phenol resin. I got 1. A pressing plate 4 fixed to the tip of the piston rod 3 of the air cylinder 2 has an appropriate number of claws 7 protruding from the surface opposite to the end surface 6 of the slab 5, and the solid thermite piece 1 is attached to the claws 7. Lock and press plate 4
hold it. Next, the air cylinder 2 is driven to cause the piston rod 3 to protrude in the direction of the arrow X, and the thermite solid piece 1 is pressed against the center of the end face 6 of the slab 5 that has just been continuously cast and cut. The thermite solid piece 1 is heated by the heat possessed by the slab 5 and ignites in about 20 to 30 seconds after pressure welding, and the iron oxide is reduced by the thermite reaction for about 5 to 10 seconds, and the heat of reaction causes the slab 5 to ignite. The vicinity of the part of the end face 6 where the thermite solid piece is pressed is locally melted. After the thermite reaction is completed, the piston rod 3 is retracted and allowed to cool naturally.
The molten part of the iron oxide and the molten iron oxide in the thermite agent solidify, thereby sealing the cavity 8 exposed at the end face 6.

The slabs subjected to the above-mentioned end face treatment have extremely little occurrence of dot scale, which is characteristic of end face oxidation after heating in a heating furnace. The amount required for rounding down is reduced to about 1/10.

The present invention is not limited to the above-described embodiments; for example, the raw material blending ratio and shape of the thermite solid pieces may be other than those described above. Also, devices other than those described above may be used for pressing the thermite solid pieces against the end faces of the slabs. In addition, in the above example, since the end face treatment was performed on the slab immediately after cutting, the heat held by the slab can be used most effectively for igniting the solid thermite pieces, and during subsequent transportation to a heating furnace etc. Although there is an advantage that end face oxidation is also prevented, the above end face treatment may be performed immediately before charging into the heating furnace, depending on the convenience of the conveyance route of the slab after casting.

The above describes the end face treatment of hot slabs.
The present invention can also be applied to end face treatment of cold slabs, in which case a heating source such as a gas burner may be used to heat the solid thermite slab and ignite it.

As explained above, according to the present invention, the thermite agent is solidified using a binder and the end face of the slab is locally melted using the thermite solid pieces, so the thermite agent can be used in a solid state that is extremely easy to handle. The end face oxidation prevention treatment of the slab can be performed quickly and easily through a simple treatment process, and the treatment equipment can be easily automated.

[Brief explanation of drawings]

FIG. 1 is a process explanatory diagram showing an embodiment of the present invention. 1... solid piece of thermite, 5... cast piece, 6...
End face.

Claims (1)

[Scope of Claims] 1. A solid thermite piece made by solidifying a thermite agent using a binder is pressed against the center of the end face of a cast piece, and the solid thermite piece is heated and ignited to cause a reaction of the solid thermite piece. A method for treating an end face of a slab, characterized in that the vicinity of the pressed part of the thermite solid piece of the slab is melted by heat, and then solidified. 2. The method for treating the end face of a cast slab according to claim 1, wherein the solid piece of thermite is heated and ignited using the heat possessed by the slab.