JP5798945B2 - Continuous casting mold and continuous casting equipment - Google Patents

Description

  The present invention relates to a continuous casting mold used in a continuous casting apparatus for continuously casting a casting made of magnesium or a magnesium alloy (hereinafter collectively referred to as “magnesium alloy”), and continuous casting using the same. It relates to the device.

Conventionally, in a magnesium alloy continuous casting apparatus, molten magnesium alloy is supplied from a holding furnace to a continuous casting mold via a tundish and solidified through primary cooling by a continuous casting mold and secondary cooling by direct water cooling. Then, it is drawn in the extending direction of the continuous casting mold and formed into a casting.
The continuous casting apparatus can be generally classified into a vertical (vertical) continuous casting apparatus and a horizontal (horizontal) continuous casting apparatus.

In the vertical continuous casting machine, molten metal is introduced from the upper opening into a cylindrical mold installed so that the holes communicate with each other in the vertical direction, and the casting is discharged or pulled out by its own weight from the lower opening. A casting is produced. On the other hand, in the horizontal continuous casting apparatus, the molten metal is introduced from one opening into a cylindrical mold installed so that the holes communicate with each other in the horizontal direction, and the casting is continuously pulled out while supporting the casting from the other opening. Castings are produced.
When the vertical continuous casting apparatus and the horizontal continuous casting apparatus are compared, there are merits and demerits, respectively, which are selectively used according to requirements in the scene where casting is performed.

  From the viewpoint of production efficiency, these vertical continuous casting equipment and horizontal continuous casting equipment have come to be applied in many situations. Various studies have been conducted on molds that have a large effect on objects.

For example, in Patent Document 1, the inner diameter of a continuous casting mold is formed in a taper shape that spreads at a predetermined angle toward the casting direction, and the thermal conductivity is 0.7 cal / cm · sec · ° C. (293 W / m · K). As described above, a continuous casting mold made of a material having a yield stress of 250 MPa or more is disclosed.
According to the continuous casting mold described in Patent Document 1, when casting aluminum or an aluminum alloy (hereinafter collectively referred to as “aluminum alloy”), a casting having a good surface shape is produced with high production. The effect that it can be manufactured with the property is exhibited.

JP 2006-110558 A

  However, the technique described in Patent Document 1 is a technique related to a continuous casting mold that solves a problem inherent to an aluminum alloy, and is not related to a magnesium alloy. Therefore, even if the technique described in Patent Document 1 is simply applied to continuous casting of a magnesium alloy, the same effect as that applied to continuous casting of an aluminum alloy is naturally not obtained. In detail, when the technique described in Patent Document 1 is applied to continuous casting of a magnesium alloy, a deep uneven shape is formed on the cast surface after casting.

  Then, this invention makes it a subject to provide the casting mold and continuous casting apparatus which can manufacture the casting which has a favorable surface shape in performing the continuous casting of the casting which consists of magnesium alloys.

In order to solve the above problems, continuous casting mold according to the present invention is a continuous casting mold for use in continuous casting of castings made of magnesium alloy, among the continuous casting mold, before Symbol casting a portion in contact, the thermal conductivity at 20 ° C. which is characterized in that the mold ring 10~150W / m · K is provided.

According to this continuous casting mold, a casting made of a magnesium alloy is used by using a material having a thermal conductivity of 10 to 150 W / m · K at 20 ° C. for the portion in contact with the casting of the continuous casting mold. Can be cooled properly. Specifically, the portion of the continuous casting mold that comes into contact with the casting is made of a material having a thermal conductivity of 150 W / m · K or less (20 ° C.), so that the casting is rapidly cooled. The formation of uneven shapes on the surface can be prevented. That is, a casting having a good surface shape can be produced.
On the other hand, the portion of the continuous casting mold that comes into contact with the casting is made of a material having a thermal conductivity of 10 W / m · K or more (20 ° C.), so that it takes a very long time to cool the casting. A reduction in casting speed (a reduction in productivity) can be avoided. Further, the portion of the continuous casting mold that comes into contact with the casting is made of a material having a thermal conductivity of 10 W / m · K or more (20 ° C.), so that the heat removal at the time of solidification of the casting is insufficient. Surface roughness can be avoided.

Further, the continuous casting mold according to the present invention, among the continuous casting mold, the portion in contact with the front Symbol casting, thermal conductivity at 20 ° C. is provided a mold ring 100~150W / m · K It is preferable.

  According to this continuous casting mold, the portion in contact with the casting of the continuous casting mold is made of a material having a thermal conductivity (20 ° C.) of 100 W / m · K or more, so that the casting is rapidly cooled. For this reason, it is possible to improve the casting speed, and it is possible to ensure sufficient productivity. That is, according to this continuous casting mold, it is possible to achieve both good surface shape and productivity of the cast product to be manufactured.

The continuous casting apparatus according to the present invention includes the above-mentioned continuous casting mold.
According to this continuous casting apparatus, by providing the continuous casting mold, it is possible to manufacture a casting having a good surface shape. Moreover, sufficient productivity can be ensured by providing the mold for continuous casting.

According to the continuous casting mold according to the present invention, a casting having a good surface shape is manufactured by using a material having a predetermined value of thermal conductivity for a portion in contact with the casting of the continuous casting mold. Can do. In addition, since the casting is rapidly cooled, sufficient productivity can be ensured.
According to the continuous casting apparatus of the present invention, a casting having a good surface shape can be produced by providing the continuous casting mold. Moreover, sufficient productivity can be ensured by providing the mold for continuous casting.

It is sectional drawing which showed the structure of the continuous casting apparatus which concerns on embodiment of this invention. It is sectional drawing which showed the structure of the casting mold for continuous casting which concerns on embodiment of this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings as appropriate.
≪Schematic configuration of continuous casting equipment≫
First, with reference to FIG. 1, the structure of the continuous casting apparatus D provided with the casting mold 1 for continuous casting which concerns on this invention is demonstrated.
The continuous casting mold 1 and the continuous casting apparatus D will be described by taking the case of a so-called horizontal type (horizontal type) as an example, but the present invention relates to a vertical (vertical type) continuous casting mold and continuous casting apparatus. It can also be applied to.

The continuous casting apparatus D is an apparatus for producing a magnesium alloy casting W by horizontal continuous casting. The continuous casting apparatus D further includes the tundish 20 that stores the molten metal M, the connecting member 7 that is connected to the tundish 20 and sends the molten metal M in the direction of the arrow, and the molten metal M that is sent out from the connecting member 7 is further arrowed. Ceramic nozzle 4 fed in the direction, continuous casting mold 1 to be cast W by cooling the molten metal M fed from the ceramic nozzle 4, and drawing to draw the cast W fed from the continuous casting mold 1 Device 30.
The continuous casting apparatus D includes a cooling water transport pipe and a lubricating oil transport pipe (not shown). From these transport pipes, a cooling water supply hole 5 and a lubricating oil supply hole 6 of the continuous casting mold 1 described later are provided. The cooling water and the lubricating oil may be introduced from the outside (see FIG. 2). Further, the continuous casting apparatus D includes a holding furnace (not shown) for holding the molten metal M supplied from the melting furnace, a molten metal hot water supply pipe (not shown) for supplying the molten metal M to the tundish 20 from the holding furnace, May be provided.

<Continuous casting mold>
Next, the continuous casting mold 1 will be described with reference to FIG.
The continuous casting mold 1 cools the molten metal M introduced in the direction of the arrow from the ceramic nozzle 4 to produce a casting W having a predetermined diameter.
The continuous casting mold 1 has a substantially cylindrical shape having an inner diameter that is the same as the outer diameter of the casting W to be manufactured, and is formed with a cooling water supply hole 5 and a lubricating oil supply hole 6 (FIG. 2). (See (a)).
The continuous casting mold 1 may be configured by combining a plurality of members.

  The cooling water supply hole 5 cools both members by introducing cooling water sent from a cooling water transport pipe (not shown) into the surface of the continuous casting mold 1 and the surface of the casting W. Moreover, the said lubricating oil supply hole 6 can send out the casting W appropriately by introduce | transducing into the casting W surface the lubricating oil sent from the lubricating oil transport pipe which is not shown in figure.

The molten metal M (cast W) is sent out in the direction of the arrow while contacting the inner peripheral surface 1a of the continuous casting mold 1, and a mold ring 3 is provided on the radially inner side of the inner peripheral surface 1a. (See FIG. 2B). In this case, the molten metal M (cast W) is sent out in the direction of the arrow while being in contact with the inner peripheral surface 3 a of the mold ring 3.
In addition, about the structure of the casting mold for continuous casting, although two structures of Fig.2 (a) and (b) were demonstrated, it is not limited to the said structure.

(Materials constituting continuous casting mold)
The portion of the continuous casting mold 1 that contacts the casting W is made of a material having a thermal conductivity of 10 to 150 W / m · K at 20 ° C.
The portion is made of a material having a thermal conductivity of 150 W / m · K or less (20 ° C.), thereby preventing the formation of uneven shapes on the surface of the cast W accompanying the rapid cooling of the cast W. Can do. That is, the casting W having a good surface shape can be manufactured.
On the other hand, since the portion is made of a material having a thermal conductivity (20 ° C.) of 10 W / m · K or more, the casting speed is lowered (productivity is reduced due to the time required for cooling the casting W). Can be avoided. In addition, by making the part of a material having a thermal conductivity (20 ° C.) of 10 W / m · K or higher, avoid surface roughness caused by insufficient heat removal during solidification of the cast W. Can do.

In addition, it is preferable that the part which contact | connects the casting W is comprised from the material whose heat conductivity in 20 degreeC is 100-150 W / m * K.
The casting portion can be rapidly cooled by forming the portion made of a material having a thermal conductivity (20 ° C.) of 100 W / m · K or more. Productivity can be ensured.

Here, the portion in contact with the casting W is the portion of the inner peripheral surface 1a of the continuous casting mold 1 that comes into contact with the casting W (or molten metal M) during casting (in the case where a mold ring is provided, the inner peripheral surface). 3a portion), specifically, a portion from the inner peripheral surface 1a (inner peripheral surface 3a) in contact with the casting W to 2 mm radially outward.
That is, the effect can be exhibited when at least the portion of the continuous casting mold 1 is made of the material. In other words, the part comprised from the said material among the casting molds 1 for continuous casting should just be 2 mm or more from the inner peripheral surface 1a (inner peripheral surface 3a) which contacts the casting W to radial direction outer side.
In addition, since at least the part which contact | connects the casting W among the continuous casting molds 1 should just be comprised from the said material, Naturally, the whole continuous casting mold 1 may be comprised from the said material.

  The specific material type (metal type) is not particularly limited as long as it satisfies the thermal conductivity. For example, stainless steel, lead, carbon and the like.

<Other members>
About the continuous casting apparatus D, although it does not specifically limit about members other than the casting mold 1 for continuous casting, What is necessary is just to use the thing of the following structures.
The tundish 20 is a tank for storing a molten M of magnesium alloy.
The ceramic nozzle 4 is a nozzle made of ceramic having heat resistance, and supplies the molten metal M in the tundish 20 to the continuous casting mold 1. The ceramic nozzle 4 connects the tundish 20 and the continuous casting mold 1 via the connecting member 7. The connecting member 7 may be made of a heat-resistant ceramic or the like.

  The drawing device 30 is a device that pulls out the casting W sent from the continuous casting mold 1 and is rotated by, for example, a motor (not shown). A plurality of the drawing devices 30 are arranged so as to be laid under the casting W.

<Molten metal and casting>
The molten metal M is a metal melted in a melting furnace (not shown) and is made of a magnesium alloy.
The casting W is a slab (ingot) cast by the continuous casting mold 1 of the continuous casting apparatus D and solidified by the molten metal M. For example, the casting W has a round bar shape with a diameter of several tens to 100 mm. Manufactured as follows.

≪Operation of continuous casting machine≫
Next, operation | movement of the continuous casting apparatus D provided with the casting_mold | template 10 for continuous casting which concerns on this invention is demonstrated.

  As shown in FIG. 1, in the continuous casting apparatus D, the molten magnesium M stored in the tundish 20 passes from the tundish 20 through the ceramic nozzle 4 via the connecting member 7 into the continuous casting mold 10. be introduced. And the molten metal M is heat-extracted through the inner peripheral surface 1a in the continuous casting mold 10, and solidifies from the surface (surface) that contacts the inner surface 1a (see FIG. 2 (a)).

Here, a lubricating film is formed between the surface of the molten metal M (cast W) and the inner peripheral surface 1a of the continuous casting mold 10 (mold body 1) by the lubricating oil supplied from the lubricating oil supply hole 6. Is formed. Further, since the casting W is drawn at a predetermined speed by the drawing device 30, the solidified casting W moves at a predetermined speed along the inner peripheral surface 1a of the continuous casting mold 10 (mold body 1). To do. The casting W is forcibly cooled by the cooling water supplied from the cooling water supply hole 5.
By the above operation, the casting W is continuously cast by the continuous casting apparatus D.

  Note that conventionally known casting conditions may be used for other casting conditions that are not explicitly described.

  Next, an example that satisfies the requirements of the present invention and a comparative example that does not satisfy the requirements of the present invention will be described in detail.

(Continuous casting mold)
The following three molds were prepared as continuous casting molds.
Continuous casting mold No. 1
Mold name: Copper mold Mold material: Chromium copper Thermal conductivity: 376 (W / m · K)
Structure: The structure shown in FIG. 2A, in which the mold body 1 is made of the above material.
Continuous casting mold No. 2
Mold name: Carbon sleeve mold Mold material: Carbon Thermal conductivity: 120 (W / m · K)
Structure: The structure shown in FIG. 2B, in which the mold ring 3 is made of the above material. The mold body 1 is constituted by a copper mold.
Continuous casting mold No. 3
Mold name: Stainless steel mold Material: SUS304
Thermal conductivity: 16 (W / m · K)
Structure: The structure shown in FIG. 2A, in which the mold body 1 is made of the above material.

(Molten metal and casting)
As the molten metal, a magnesium alloy JIS “MC2” alloy (= ASTM “AZ91”) was used. Moreover, the diameter of the manufactured casting was φ65 mm.

(Evaluation)
About the manufactured casting, the surface shape (appearance shape shown in Table 1) from right side with respect to the casting direction was observed with a stereomicroscope. Moreover, it was the cross section of the same direction as a casting direction, and the upper end 4mm (cross-sectional micro shape shown in Table 1) was observed using the optical microscope. The observation results (photos) are shown in Table 1.

(Examination of results)
Continuous casting mold No. 1 (copper mold) had a thermal conductivity that exceeded the upper limit defined in the present invention. Therefore, although productivity was good, the surface shape of the casting was bad.

  Continuous casting mold No. No. 2 (carbon sleeve mold) corresponded to the range in which the thermal conductivity is defined in the present invention. Therefore, productivity was good and the surface shape of the casting was good.

  Continuous casting mold No. No. 3 (stainless steel mold) corresponded to the range specified by the present invention in terms of thermal conductivity. Therefore, productivity was good and the surface shape of the casting was good. However, no. Compared with 2, productivity was slightly inferior.

Note that the continuous casting mold no. When the casting speed of 1 is 1, continuous casting mold no. No. 2 is 0.58, mold No. for continuous casting. 3 was 0.27.
That is, according to the present invention, when continuously casting a casting made of a magnesium alloy, it was found that a casting having a good surface shape can be produced while ensuring productivity applicable to practical use.

1 Continuous casting mold (mold)
DESCRIPTION OF SYMBOLS 1a Inner peripheral surface of a mold body 3 Mold ring 3a Inner peripheral surface of a mold ring 4 Ceramic nozzle 5 Cooling water supply hole 6 Lubricating oil supply hole 7 Connecting member 20 Tundish 30 Drawing device W Cast product D Continuous casting device M Molten metal

Claims (3)

A casting mold for continuous casting of a casting made of magnesium or a magnesium alloy,
Wherein one of the continuous casting mold, the portion in contact with the front Symbol castings, 20 ° C. in the thermal conductivity of 10~150W / m · K of the continuous casting mold, wherein the mold ring is provided. Among the continuous casting mold, the portion in contact with the front Symbol casting, according to claim 1, thermal conductivity at 20 ° C. which is characterized in that the mold ring 100~150W / m · K is provided Mold for continuous casting.   A continuous casting apparatus comprising the continuous casting mold according to claim 1.