JPS6250066A - Mold for building up by continuous tinkering - Google Patents

Abstract

PURPOSE:To prevent the transverse crack of a build-up layer by the construction consisting in extending upward the top end face of a graphite sleeve from the top surface of a water cooling type jacket to project the jacket and imposing a refractory flask onto the projecting graphite sleeve. CONSTITUTION:The mold for building up is constituted by extending and projecting the top end face of the sleeve 2 consisting of a graphite material to the position upper than the top surface of the water cooling type jacket 3 and imposing the refractory flask 1 on the sleeve 2. A base metal 5 is positioned into the mold space and a molten metal 6 is poured therein. The material 5 is gradually lowered while the molten metal 6 is stirred by an induction heating coil 4, then the solidification of the molten metal 6 is always started in the region of the graphite sleeve 2 and thinkering progresses. The transverse crack of the build-up layer is thereby prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for continuous casting overlay.

[Conventional technology]

Providing a graphite lining on the inner surface of the cooling jacket as a cooling mold for continuous casting overlay was introduced in 1986.
It is described in the publication No.-2846.

[Problem that the invention seeks to solve]

Although this graphite lining is extremely effective in slowly cooling the built-up layer, it has the disadvantage that horizontal splits occur in the built-up layer.

Repairing transverse cracks is extremely difficult and impossible depending on the material.

An object of the present invention is to provide a new structure of a build-up mold that can prevent horizontal cracking of the build-up layer.

[Means for solving problems]

As a result of intensive research into the prevention of lateral cracks in built-up layers, the present inventors were unable to obtain the following new knowledge.

That is, a sleeve made of graphite material is fitted into the inner surface of a water-cooled jacket, and the upper end surface of this sleeve is extended above the upper surface of the jacket to protrude, and the fireproof frame is placed above the protruding sleeve. It has been found that horizontal cracking of the built-up layer can be prevented by creating a structure in which it is placed on the cladding layer.

The present invention has been made based on the above findings.

[For production]

Although the reason for the occurrence of horizontal cracks in the overlay layer is not necessarily clear,
It is assumed that this is due to the following usage.

That is, since transverse cracks are likely to occur in areas where the growth of the solidified shell is immature, if the slidability of the shell near the point where growth begins is low, transverse cracks will occur frequently. Specifically, as long as the growth of the solidified shell occurs on the inner surface of the graphite sleeve, there will be sufficient sliding, and no transverse cracking will occur. However, when the starting point of the shell exceeds the upper end of the graphite sleeve and reaches the refractory frame, the solidified shell begins to grow there, and since the sliding properties are not high, transverse cracking occurs.

However, if the upper end of the graphite sleeve extends above the upper surface of the water-cooling jacket, even if the growth point of the solidified shell is above the jacket, the graphite sleeve provides good sliding properties and no transverse cracking occurs. Further, since the upper end of the graphite sleeve is close to the heating coil, the temperature is sufficiently high, and the solidified shell does not go above the upper end. In this way, solidification can be set to always begin in the area of the graphite sleeve, and transverse cracking can be prevented due to sufficient sliding properties.

The above is the theory that is considered to be the reason for the action of the present invention,
It should be noted that the present invention is not bound by such theory.

〔Example〕

The present invention will be explained in detail with reference to the drawings.

As shown in FIG. 1, the overlay mold of the present invention surrounds an annular fireproof frame l, an annular graphite sleeve 2 coaxially connected below it, and a part of the sleeve 2. It has an annular water cooling jacket 3. Further, an induction heating coil 4 is provided on the outer periphery of the fireproof frame 1. A cylindrical base material 5 to be overlaid is lowered within the vertical cylindrical space at the center of the mold formed by these parts by a suitable drive device (not shown). The gap between the cylindrical base material 5 and the inner wall of the mold corresponds to the amount of overlay.

Overlay work is carried out as follows. First, the base material 5 is installed in the mold space, and after setting it at a predetermined vertical position, molten metal 6 is poured from a ladle into the gap between the mold and the base material. The injected molten metal is stirred by the coil 4 and welded to the base material 5. The lower part of the molten metal is cooled by a water cooling jacket and solidified. Since the base material 5 gradually descends, overlaying is performed continuously.

In the mold of the present invention, the graphite-based sleeve 2 extends upward from the upper surface of the water-cooling jacket 3 and reaches the vicinity of the heating coil 4, so that solidification of the molten metal always starts in the region of the graphite-based sleeve 2.

Since the graphite-based sleeve 2 has extremely good sliding properties, the occurrence of transverse cracks when solidification starts can be suppressed.

〔Effect of the invention〕

With the above configuration, when the mold of the present invention is used, overlaying without horizontal cracking can be performed. Furthermore, since solidification always occurs on the graphite-based sleeve 2 which has good sliding properties, the surface of the built-up layer becomes extremely smooth.

Furthermore, the unevenness of the coagulation structure is also reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the mold of the present invention. ■... Fireproof frame, 2... Graphite sleeve, 3...
Water cooling jacket, 4... Induction heating coil, 5... Base material, 6... Molten metal.

Claims (1)

[Claims] In a continuous casting overlay mold having a refractory frame surrounded by an induction heating coil on the outside and a water-cooled jacket coaxially installed below the frame, the inner surface of the jacket is made of graphite-based material. 1. A mold for continuous casting overlay, characterized in that a sleeve is fitted into the mold, and the upper surface of the sleeve is extended and protrudes above the upper surface of the jacket.