JPH04258347A - Mold for continuously casting planar material and casting method - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks, etc., by supporting an end part at the pouring side of a casting material in one part of a long wall side mold frame rockingly with a shaft to a supporting member and also rocking the end part at the outlet side of the casting method in the long wall side mold frame in touching/ detaching direction to the casting material in the mold. CONSTITUTION:This mold is constituted of a pair of the long wall side mold frames 1a, 1b opposed to each other and a pair of short wall side mold frames arranged by adhering them to these both end faces and a cavity C for casting a planar material having a slender flat rectangle is formed in the inner part of the mold. At least, the end part at the pouring side of casting material in a part of the above-mentioned long wall side mold frame is supported rockingly with a rocking shaft 3 to the supporting member and also the end part at the outlet side of casting material in the long wall side mold frame is rocked in touching/detaching direction to the casting material in the mold. By this method, while making the above-mentioned mold frame adhere to the casting material inspite of the shrinkage due to the temp. drop of the casting material in the mold except drawing time of the casting material to the mold, the casting material is quickly cooled in good condition and the generation of the cracks is prevented and the planar material having no flaw can be cast.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold and a casting method used for continuously casting plate-like objects having a rectangular cross section, such as metal plates.

0002

[Prior Art] When continuously casting the above-mentioned plate-like products, conventionally, a pair of molds are placed opposite each other corresponding to the long side and short side of the plate-like product with a rectangular cross section to be cast. Molten metal (cast material) is injected from above into a vertical mold, for example, and the cast material solidified into a predetermined shape by the mold is successively drawn downward, thereby continuously casting plate-shaped objects. It is something to do. In this case, the flow rate of the molten metal injected into the mold is controlled in accordance with the casting speed so that the level of the molten metal is maintained constant, and the molten metal successively contacts the inner surface of the mold just below the molten metal level. The surface temperature of the molten metal rapidly decreases due to the heat dissipated by the contact, reaching the freezing point, and a thin solidified shell is formed on the surface of the contact area. The solidified shell sequentially moves downward while contacting the inner surface of the mold, and the thickness of the solidified layer increases toward the center of the molten metal as time passes. At that time, if the frictional force that acts between the inner surface of the mold and the solidified shell is large, cracks may occur in the solidified shell. A highly durable lining (e.g. graphite lining) is applied.

[0003] Furthermore, when a solidified shell is formed on the surface (periphery) of the molten metal poured into the mold as described above, the temperature of the molten metal and casting material further decreases during subsequent solidification to the center. Because of the shrinkage, if the opposing molds are arranged parallel to each other in the vertical direction, a gap is created between the cast material and the inner surface of the mold by the amount of shrinkage. When such a gap occurs, the contact between the cast material and the inner surface of the mold is cut off, the heat dissipation effect described above is reduced, and the solidification rate and thus the casting rate are reduced. Conventionally, in order to solve this problem, for example, the length (height) of the mold is shortened, and the cast material is pulled out of the mold early after solidification and cooled directly with water or the like. Alternatively, various attempts have been made, such as fixing the gap between mutually opposing formworks in an inclined state so that the gap becomes narrower toward the bottom in response to the solidification and shrinkage of the cast material. However, even if it is pulled out of the mold early after solidification and cooled directly with water, etc., as in the former case, the height of the mold must be at least 250 mm in order to prevent unexpected situations such as destruction of the solidified shell.
It is necessary to maintain the thickness at about 300 mm, and the casting speed cannot necessarily be increased. In addition, when the mold interval is fixed at an angle so that it gradually narrows toward the bottom as in the latter case, it is not easy to accurately estimate the amount of solidification shrinkage according to the casting conditions, and if the interval is too narrow, There have been problems such as an increase in the frictional force between the mold and the solidified shell, leading to the destruction of the shell or the inability to pull it out.

0004

The present invention has been proposed in view of the above-mentioned problems, and it is an object of the present invention to reduce the frictional force between the mold and the solidified shell as much as possible, and to prevent the mold from shrinking regardless of the solidification shrinkage of the cast material. It is an object of the present invention to provide a continuous casting mold and a casting method for a plate-shaped article that can satisfy the conflicting requirements of maintaining good adhesion with a solidified shell.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration. That is, the mold for continuous casting of a plate-like object according to the present invention is a plate-like object formed by disposing a pair of molds facing each other corresponding to the long side and the short side of the plate-like object having a rectangular cross section to be cast. In a mold for continuous casting of a product, at least one casting material injection side end of the long side mold is supported by a support member so as to be swingable about a shaft,
The present invention is characterized in that it includes a swinging means for swinging the casting material outlet side end of the long-side mold in a direction toward and away from the casting material in the mold. Further, the casting method according to the present invention comprises disposing a pair of molds facing each other corresponding to the long side and the short side of the plate-like object having a rectangular cross section to be cast, and at least one pair of the molds on the long side side are arranged opposite to each other, respectively. When casting a plate-like object using a mold in which one end of the outlet side of the casting material is configured to be able to swing inward, the above-mentioned swinging motion of the mold frame configured to be swingable inward. The present invention is characterized in that this is synchronized with the operation of stopping the withdrawal of the casting material from the mold.

[0006]

[Function] As described above, the mold for continuous casting of a plate-shaped article according to the present invention has at least one casting material injection side end of the long side mold supported by a support member so as to be swingable about an axis.
By providing a swinging means for swinging the end of the casting material outlet side of the long side formwork in the direction toward and away from the casting material in the mold, it is possible to reduce the temperature drop of the casting material in the mold. It becomes possible to bring the formwork into close contact with the casting material regardless of shrinkage. Further, in the casting method according to the present invention, the swinging motion of the mold frame configured to be swingable as described above inward of the mold is synchronized with the movement of stopping the withdrawal of the casting material from the mold.
When the casting material is not being pulled out from the mold, the above-mentioned swingable mold frame is kept in close contact with the casting material to achieve good heat dissipation effects from the casting material, regardless of shrinkage caused by the temperature drop of the casting material within the mold. At the same time, when the cast material is pulled out, it is possible to reduce or release the adhesion force to the cast material to prevent cracks or the like from occurring in the solidified shell.

[0007]

EXAMPLES Hereinafter, a mold for continuous casting of plate-shaped articles and a casting method according to the present invention will be specifically explained based on examples. First, a casting mold according to the present invention will be described with reference to the embodiment shown in the drawings. FIG. 1 is a plan view showing an embodiment of a casting mold according to the present invention, and FIG. 2 is a partially vertical front view thereof.

The illustrated mold is composed of a pair of long-side molds 1a and 1b facing each other, and a pair of short-side molds 1c and 1c disposed in close contact with both end surfaces thereof. An elongated planar rectangular space (cavity) C for casting a plate-like object is formed inside. Each formwork 1a to 1c has a graphite lining 11 with good lubricity and heat resistance, and a water cooling block 12 made of copper or the like and having a cooling water passage 12a inside.
and a reinforcing backing plate 13, which are integrally fixed in close contact with each other with fixing bolts 2, as shown in FIG.

When casting a plate-like object with a rectangular cross section using a mold configured as described above, the molten metal (casting material) poured into the mold is gradually cooled and solidified as it comes into contact with the mold. As shown by the chain line in FIG. 2, as it goes downward, it gradually contracts and the contact with the inner surface of the mold is cut off, reducing the cooling effect. In particular, the long-side formworks 1a and 1b have a large contact area with the casting material, which influences the cooling capacity of the entire mold. Therefore, in the case of the figure, the upper part of one long side formwork 1a is swingably attached to a support member such as a pedestal not shown in the figure by the shaft 3, and
A hydraulic cylinder 4 is provided on the lower back side of the formwork 1a as a swinging means for swinging the formwork 1a inward into the space C, and the hydraulic cylinder 4 is fixed to a pedestal 5. The piston rod 4a of the hydraulic cylinder 4 is attached to the formwork 1
It is connected by a shaft 7 to a bearing member 6 attached to the back surface of a. In the case of the figure, the other long-side formwork 1b is attached to a support member 5 such as a pedestal with a shaft 3 in the same way as above, and the formwork 1b is
The formwork 1b is fixed in a non-swiveling manner by connecting the bearing member 6 attached to the lower back surface of the frame 1b with the bearing member 8 attached to the support member 5 through the shaft 7.
Similarly to a, it may be configured to be swung by a swiveling means such as a hydraulic cylinder. In addition, when casting a cast material with a long and narrow rectangular cross section continuously, the four corners of the mold are cooled quickly, and the gap between the molds 1c and 1c on the shorter sides and the cast material is not a big problem, although it depends on the width. Therefore, in the case shown in the figure, the casting materials were arranged and fixed facing each other with an interval equivalent to the width of the casting material, as in the past, but the thickness of the casting material is particularly thick, and heat dissipation to the formwork on the short side is also important. In such a case, it is desirable to configure one or both of the short-side formworks to swing in the same manner as the long-side formwork 1a.

[0010] Next, the continuous casting method of a plate-like article according to the present invention will be specifically explained by taking as an example the case where a plate-like article is continuously cast using the above-mentioned mold. As shown in FIG. 2, molten metal (casting material) at a predetermined temperature is continuously injected at a constant flow rate between the long side molds 1a and 1b which are opposed to each other at a predetermined interval t in the upper part of the mold. Then, the injected molten metal in the mold comes into close contact with the inner surface of the mold just below the molten metal surface, or, if flux is used for purposes such as lubrication, through that layer, and heat is radiated.
An extremely thin solidified shell is formed on the surface of the molten metal. As the heat is released, the thickness of the solidified shell increases and its strength increases, while the cast material apparently contracts in a direction in which the thickness of the cast material decreases as shown by the chain line in FIG. At that time, if the pressure of the molten metal inside is greater than the shell strength, the shell expands outward, and when it comes into contact with the inner surface of the mold, that part is rapidly cooled and contraction is accelerated, but as a whole, as the temperature decreases, the shell expands outward. The gap between the casting material surface and the casting material surface increases, and near the casting material exit at the bottom of the mold, there is a gap between the casting material and the inner surface of the mold on both sides of the casting material.
A gap δ on the order of % occurs.

Therefore, in the casting method according to the present invention, the inner surface of the mold is always in close contact with the surface of the cast material, even when the cast material shrinks due to temperature drop in the mold, except when the cast material is drawn out. . In the illustrated mold, the distance t between the upper parts of the long side formworks 1a and 1b where no shrinkage gap occurs
is always constant, and by swinging the lower part of one long-side formwork 1a inward of the space C by a predetermined inclination angle by the hydraulic cylinder 4, when the amount of displacement near the casting material outlet is Δ. , so that approximately Δ=2δ, thereby preventing a gap δ that gradually expands downward from occurring between the long-side formworks 1a and 1b on both sides of the casting material, and also preventing the above-mentioned hydraulic pressure. By controlling the pressure of the cylinder, an appropriate pressure is applied to the casting material to ensure close contact between both long side molds and the casting material.

[0012] Also, in order to effectively dissipate heat without causing cracks in the solidified shell, ideally there should be no relative movement between the cast material and the mold when they are in close contact. Therefore, in the casting method according to the present invention, when the casting material is drawn from the mold, the relative movement of the mold with respect to the casting material is suppressed. For example, in continuous withdrawal, the mold is moved in the same direction and at the same speed as the cast material is withdrawn. In the illustrated example, a support member 5 such as a pedestal that holds the mold is lowered together with the mold by a vertical movement mechanism or the like not shown in the figure. On the other hand, in the case of intermittent drawing, it is sufficient to bring the mold into close contact with the casting material while the drawing operation of the casting material is stopped, and to separate it when drawing out the casting material, and the above-mentioned vertical movement mechanism of the pedestal, etc. is not necessary.

[0013] In any case, in open molding, since the level of the molten metal within the mold fluctuates, it is desirable to set the contact time short to prevent casting surface defects. On the other hand, in a closed mold, the upper part of the mold is directly connected to the molten metal pool via a break ring or the like, so there is no molten metal level in the mold, and the above-mentioned defects do not occur.

As mentioned above, the heat dissipation effect due to the approximate front surface of the long side formwork being in close contact with the casting material is extremely large, and even with a contact time of several seconds per cycle, heat can be dissipated well and quickly, so that the conventional mold Compared to casting with a fixed frame interval, it is possible to significantly increase the casting speed. In addition, after the long side formwork has come into close contact with the casting material, the hydraulic pressure must be instantly released, or the mold must be retreated by a certain stroke.
(increase the gap between the lower molds) to reduce or eliminate friction with the casting material. At this time, by returning the mold upward or pulling out the cast material, the mold and the cast material can be moved relative to each other, and cracks in the solidified shell due to friction can be prevented.

[Experimental Example] Using the mold of the above example, a copper plate having a rectangular cross-sectional size of 25 mm x 300 mm was continuously cast. The composition of the molten copper is 0.02% by weight of P and 0% of Fe.
．． 01% by weight, and the balance was Cu. The casting conditions were an average drawing speed of 650 mm/min, and a pouring temperature of 1160 mm/min.
It was set to ℃. As a result, the temperature of the cast material at the mold outlet was 240℃.
The temperature was about 330°C, and a good cast product without cracks etc. was obtained.

As a comparative example, a copper plate was formed under the same conditions as above using the same mold as in the above experimental example except that there was no swinging means such as a hydraulic cylinder and the long side formwork was fixed substantially parallel. When continuous casting was performed, no cracks or the like occurred, but the temperature of the cast material at the mold outlet was 680°C to 730°C, and the heat dissipation effect was significantly reduced compared to the above experimental example, and the casting speed had to be slowed considerably. I found out that it doesn't happen.

[0017]

[Effects of the Invention] As explained above, the mold for continuous casting of a plate-shaped article according to the present invention is capable of swinging at least one casting material injection side end of the long-side mold about the support member. In addition to supporting the casting material outlet side end of the long side formwork,
With an extremely simple structure that only includes a swinging means that swings the casting material in the direction toward and away from the casting material in the mold, the above-mentioned formwork can be moved against the casting material regardless of shrinkage due to temperature drop of the casting material in the mold. It is possible to make sure that it is in close contact with the Further, in the casting method according to the present invention, the swinging motion of the swingable mold frame inward of the mold is synchronized with the stopping motion of pulling out the casting material from the mold. Other than that, the above swingable mold frame can be brought into close contact with the casting material regardless of shrinkage due to temperature drop of the casting material in the mold, and the casting material can be cooled well and quickly.
When pulling out the cast material, it is possible to reduce or release the adhesion to the cast material to prevent cracks from forming in the solidified shell, allowing for rapid casting of plate-like products without defects such as cracks. There are other effects.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a mold for continuous casting of plate-shaped articles according to the present invention.

FIG. 2 is a partially longitudinal front view of a mold according to the present invention.

[Explanation of symbols]

1a, 1b Long side formwork 1c Short side formwork 3 Swing axis 4 Swinging means (hydraulic cylinder)

Claims (2)

[Claims] Claim 1. A mold for continuous casting of a plate-shaped article, comprising a pair of molds arranged opposite to each other corresponding to the long side and the short side of the plate-shaped article having a rectangular cross section to be cast. One end of the long side formwork on the casting material injection side is supported swingably on a support member, and the end of the long side formwork on the casting material outlet side is connected to the casting material in the mold. 1. A mold for continuous casting of a plate-shaped article, characterized in that the mold is equipped with a swinging means for swinging the mold in the direction of approaching and separating. [Claim 2] A pair of molds are disposed facing each other corresponding to the long side and short side of a plate-shaped object having a rectangular cross section to be cast, and casting of at least one of the long side molds is provided. When casting a plate using a mold in which the material outlet side end is configured to be able to swing inward of the mold, the swinging motion of the mold frame configured to be able to swing inward is controlled by the mold. 1. A method for continuous casting of a plate-like material, characterized in that the timing of stopping a drawing operation of a cast material is synchronized with the stop timing of a drawing operation of a cast material.