JP2007237208A - Method and apparatus for producing magnesium-based metal sheet material, and method for producing magnesium-based decorative metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method and an apparatus with which in the case of producing a magnesium-based metal sheet material with a continuous casting, the sheet material can be produced in good yield by preventing the development of defect, such as crack. <P>SOLUTION: When magnesium-based molten metal is supplied in a gap between one pair of rolls 4a,4b for casting and sheet-like material is cast to make the sheet material, as at least one of roll between the rolls for casting, the roll forming recessed and projected parts on the surface, is used. On the sheet material with this way, the recessed and projected pattern is clearly transferred on the surface, and the sheet is useful as a magnesium-based decorative metal sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a plate material of magnesium or an alloy thereof and a manufacturing apparatus thereof, and relates to a method of manufacturing a magnesium metal plate material for manufacturing a metal plate material by casting magnesium or an alloy thereof, a manufacturing apparatus used therefor, It relates to the manufacturing method.

Magnesium has abundant resources among metals, and its specific gravity is lighter than that of aluminum or iron, so that it is attracting attention as a lightweight component. Although the actual strength of magnesium is inferior to that of aluminum or iron, it is lightweight and has high specific strength, and can be used instead of aluminum for the same strength requirements. Therefore, it is expected to be applied to products that require weight reduction such as nursing care and welfare products.
Moreover, since magnesium is excellent in electromagnetic shielding performance, it has excellent characteristics that it can prevent electromagnetic noise of electronic equipment, has a high ability to absorb vibration, and can reduce noise.
Furthermore, magnesium is resistant to deformation and impact, and has a surface that can be easily cut. In addition, since it has a low melting point and is excellent in recyclability, it has excellent properties of being a metal suitable for protecting the global environment.

  A technology for producing a magnesium-based metal thin plate by casting and rolling has been developed (see Patent Document 1). In this method, molten magnesium metal is supplied between twin rolls, the plate material is cast, and then rolled. In this method, the temperature of the magnesium metal at the time of entering the casting process is controlled within a specific range, so that the quality is excellent. It is possible to manufacture a thin plate material.

  By the way, the above method enables continuous casting of a magnesium-based metal sheet material, which has been extremely difficult in the past, but the obtained sheet material has cracks or spots transverse to the longitudinal direction of the casting. In order to produce a thin plate material that is easily cracked and has a good yield, complicated work is required for setting the conditions, and workability is low.

Japanese Patent No. 3503898 Specification

The present invention realizes a method and an apparatus capable of preventing the occurrence of cracks and the like and producing a thin plate material excellent in surface properties with a high yield when producing a magnesium-based metal thin plate by continuous casting and rolling. It is aimed.

  According to the present invention, there is provided a method of manufacturing a plate material of magnesium or an alloy thereof (hereinafter, magnesium and its alloys are collectively referred to as a magnesium-based metal) by supplying a molten magnesium-based metal between at least a pair of rolls. In producing a plate material by casting to a predetermined thickness solidified to a temperature, at least one roll is a roll having an uneven portion on its surface.

  In another magnesium-based metal plate manufacturing method according to the present invention, a magnesium-based metal melt is supplied between at least a pair of rolls and cast to a predetermined thickness solidified at a predetermined temperature to obtain a plate material. Further, at least one roll is a roll having a concavo-convex portion on the surface thereof, whereby a plate material having a convex portion on the surface is cast and subsequently rolled to produce a magnesium-based metal thin plate. .

The depth of the concavo-convex portion formed on the roll surface is preferably 0.01 to 3 mm, and more preferably 0.1 to 1 mm. Moreover, it is preferable that the diameter or width | variety of the uneven | corrugated | grooved part formed in the said roll surface is 0.01-5 mm, and the range of 0.5-2.5 mm is further more preferable. Furthermore, it is preferable that the uneven | corrugated | grooved part formed in the said roll surface is formed in the range of 0.5-100 mm in distance with an adjacent uneven | corrugated | grooved part, and the range of 1-10 mm is further more preferable. The concavo-convex portions formed on the roll surface are preferably formed at a density of 0.01 to 400 pieces / cm ² , and more preferably 1 to 100 pieces / cm ² .

The magnesium-based metal sheet manufacturing apparatus of the present invention is a casting for casting a molten magnesium-based metal between at least a pair of first rolls and applying pressure to cast a sheet material solidified to a predetermined temperature. A roll part;
An apparatus for producing a magnesium-based metal thin plate comprising at least a rolling roll portion for applying a pressure to the cast plate material by at least a pair of second rolls and rolling to produce a magnesium-based metal thin plate having a predetermined thickness In
An apparatus for producing a magnesium-based metal thin plate, wherein at least one of the pair of first rolls has an uneven portion formed on a surface thereof.

Furthermore, the method for producing a magnesium-based metal decorative board according to the present invention includes supplying a magnesium-based metal melt between at least a pair of rolls and casting it to a predetermined thickness solidified at a predetermined temperature to manufacture a plate material. The at least one roll is a roll having an uneven portion on the surface thereof.

According to the present invention, it is possible to manufacture a plate material having a good surface property with high yield without causing spot cracks or the like on the surface of the plate material after casting.

The present invention has been made based on the following knowledge. That is, when light metal plate materials such as magnesium are produced by casting using twin rolls, the molten liquid surface that contacts the upper casting roll is locally up-and-down oscillated at the position where the molten metal contacts the twin roll. Phenomenon is observed. This is because the molten metal liquid level that contacts the upper casting roll is dragged downward as the upper casting roll rotates and moves in the direction of lowering the liquid level, but excessive local liquid level drop occurs. In addition, the liquid level rises due to repulsion due to the force of surface tension or the like. It is considered that this phenomenon is repeatedly caused by the vibration. When such a liquid level vibration occurs, on the surface of the plate material to be cast, the plate material portion in the lowered position and the plate material portion in the raised position have different cooling conditions for the plate material. There is a periodic variation in thickness. As the plate thickness periodically fluctuates, cracks or cracks that appear to be caused by uneven cooling rates are observed around the fluctuating portion.
In the above description, the upper roll of the casting roll has been described, but the same phenomenon occurs in the lower roll.

As a result of various investigations on means for avoiding such a phenomenon, the present inventors alleviated uneven heat transfer by forming irregularities on the surface of the twin rolls, and resolved the poor surface properties of the cast plate material. In particular, the present invention has been completed. Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, the concavo-convex portion formed on the roll surface may be a concave portion formed by machining the surface of the roll, such as cutting, or a convex portion formed by a method such as pressurizing the roll surface. It may be.

[First Embodiment]
FIG. 1 is a schematic side view showing the overall configuration of a magnesium-based metal sheet manufacturing apparatus according to an embodiment of the present invention. In the apparatus for manufacturing a magnesium-based metal plate shown in FIG. 1, the apparatus is generally composed of a molten metal supply unit 1 and a casting roll unit 4.

(Molten supply part)
The molten metal supply unit 1 is a mechanism for supplying a magnesium-based metal melted by a melting device (not shown) to a casting roll unit 4 composed of twin rolls for casting a magnesium-based metal in a magnesium-based metal plate manufacturing apparatus. It consists of a molten metal tank 3.

The molten metal tank 3 is for storing the molten metal 2, and is configured such that the molten metal 2 is drawn out by a casting roll portion 4 from an outlet 3 a formed on one side surface of the molten metal tank 3. Yes.
Moreover, although the bottom part of this molten metal tank 3 may be parallel to a horizontal surface, it is preferable to incline at a predetermined angle with respect to a horizontal surface. In FIG. 1, the angle β formed with the bottom of the molten metal tank 3 with respect to the horizontal plane can be 0 to 45 °. A more preferable angle is 5 to 30 °. By setting the angle formed with the horizontal surface of the bottom of the molten metal tank 3 within this range, the plate material can be stably cast without causing an abnormality such as a ripple mark on the surface of the cast plate material.

(Casting roll part)
The casting roll unit 4 is a mechanism for casting the molten magnesium-based metal supplied from the previous process onto a plate material between twin rolls at a predetermined temperature. That is, as shown in FIG. 1, the casting roll unit 4 applies pressure from above and below to the molten metal 2 to form a sheet material 7 having a predetermined thickness and temperature that can be rolled. The molten metal 2 drawn out from the three outlets 3a is composed of at least a pair of rolls, that is, a casting upper roll 5 and a casting lower roll 6 in a rotational operation state.

Among the upper and lower casting rolls 5 and 6, at least one casting roll has a plurality of concave and convex portions 22 formed on the surface thereof as shown in FIG. 2 (a). The convex and concave portions 22 of the roll are transferred to form convex portions.
2 (b), 2 (c), and 2 (d) show modifications of the uneven portions formed on the surface of the casting roll 21. FIG. As shown in FIG. 2, in the present embodiment, the concavo-convex portion has a plurality of hemispherical or bowl shapes formed on the surface of the casting roll 31 as shown in FIG. 3, which is an enlarged cross-sectional view of the main part of the casting roll. Or a concave-convex portion 32 of a semicircular or V-shaped groove (FIG. 3B) extending in the circumferential direction of the roll. The groove extending on the circumference may be a spiral groove (FIGS. 2B and 2D), or a ring-shaped groove that circulates around the roll (FIG. 3C). ). Further, the groove may be singular or plural.

  The diameter or width a of the uneven portion is preferably in the range of 0.01 to 3 mm, and more preferably in the range of 0.5 to 2.5 mm. If the irregularity diameter a is less than the above range, there is a problem of frequent occurrence of cracks due to adhesion and solidification of the roll and the molten metal, and oxidation problems. On the other hand, if the irregularity diameter a exceeds the above range, solidification is insufficient. There are problems such as the occurrence of surface defects due to cracks and the occurrence of cracks and dents that appear to be due to uneven heat transfer on the roll surface. Moreover, the depth b of this uneven | corrugated | grooved part (projection part height of a board | plate material) has the preferable range of 0.01-3 mm, and the range of 0.1-1 mm is further more preferable. When the uneven part depth b is less than this range, it is not possible to expect the effect of forming the convex part on the plate material after casting. On the other hand, when the depth of the concavo-convex portion exceeds the above range, the surface properties of the obtained plate material are disturbed, and a plate material having a uniform structure cannot be obtained. Furthermore, the pitch C of the arrangement of the concavo-convex portions 32 is preferably in the range of 0.5 to 100 mm, and more preferably in the range of 1 to 10 mm. If the pitch of the irregularities is below the above range, there are problems such as excessively non-uniform thickness due to the adhesion of rolls and molten metal and the occurrence of cracks due to solidification, resulting in high production costs. When the pitch exceeds the above range, the effect is not seen so much, and there is a problem that the commercial value is lowered.

The lower casting roll is arranged close to the molten metal outlet of the molten metal tank, and the molten metal stored in the molten metal tank adheres to the roll surface of the lower molten roll and is drawn out of the molten metal tank by its rotational force. Has been.
Further, a pair of side dams are disposed so as to be in sliding contact with both end surfaces of the lower casting roll and the upper casting roll at a position closest to the lower casting roll and the upper casting roll. The molten metal supplied between them is prevented from leaking from the end faces of these rolls.

  A rotation driving unit (not shown) is connected to each of the upper casting roll and the lower casting roll, and is configured to rotate at a predetermined rotational speed in a direction indicated by an arrow shown in FIG. As a result, the molten metal drawn out of the molten metal tank by the rotational force of the lower casting roll is formed by pressing the solidified surface from above by the upper casting roll, that is, being reduced. The load applied at this time is preferably in the range of 0.01 to 1.0 kN / mm per unit length in the width direction of the roll. When the load per unit length in the width direction of the roll falls below the above range, not only is it difficult to form a continuous plate material, but the surface of the produced plate material is roughened, which is not preferable. On the other hand, when the load per unit length in the width direction of the roll exceeds the above range, defects such as peeling occur at the center of the formed plate material, which is not preferable.

  Moreover, it is preferable that a mechanism for controlling temperature is added to each of the upper casting roll and the lower casting roll. These upper casting roll 21 and lower casting roll 22 can be formed of an iron-based alloy or a copper alloy.

(Effect of this embodiment)
According to this embodiment, the vibration of the molten metal liquid surface is relieved, and a plate material having excellent surface properties can be manufactured.
In general, in the casting of non-ferrous metal, it is necessary to use a release agent such as carbon powder, but in the method of the present embodiment, it is not necessary to use a release agent.

[Second Embodiment]
In the first embodiment, an example in which a magnesium-based metal thin plate is continuously cast is shown. However, after this casting step, a thin plate can also be manufactured by performing a rolling and / or forging step. . Hereinafter, an embodiment in which a thin plate is manufactured by performing a rolling process after a casting process will be described.

Hereinafter, the magnesium-based metal sheet manufacturing method and manufacturing apparatus of the present embodiment will be described based on one embodiment shown in FIG.
FIG. 4 is a schematic side view showing an overall configuration of an apparatus for continuously casting and rolling a magnesium-based metal plate material.

The magnesium-based metal sheet manufacturing apparatus shown in FIG. 4 generally includes a molten metal supply unit 41, a casting roll unit 44, a plate material transport unit 45, and a rolling roll unit 48.
In the present embodiment, the molten metal supply unit 41 and the casting roll unit 44 are the same as those in the first embodiment, and thus detailed description thereof is omitted.

(Transport section)
The plate material conveyance unit 45 is a mechanism for conveying the magnesium-based metal plate material formed in the previous process to the rolling roll unit 48 which is the next process. As such a mechanism, a roller conveyor or a belt conveyor can be employed. Moreover, it may be preferable to control the temperature of the board | plate material conveyed, and it is desirable to provide a temperature control apparatus in this conveyance part.

(Rolling roll part)
The rolling roll unit 48 is a step of rolling and forming the cast metal plate material conveyed in the previous step into a thin plate having a predetermined thickness. That is, the rolling roll unit 48 rolls the plate material 47 to form a magnesium-based metal thin plate, and is rolled by applying pressure to the plate material 47 from above and below by at least a pair of rolls 49 in a rotating operation state. It is configured.
At this time, the plate material 47 conveyed to the rolling roll portion has a convex portion formed by transferring the concavo-convex portion formed on the casting roll on the surface thereof. In the rolling roll portion, rolling can be performed so that the convex portion has a uniform and flat surface.
The rolling reduction ((thickness before rolling−thickness after rolling) / thickness before rolling) in the rolling roll portion is preferably in the range of 10% to 50%.
In addition, a temperature adjusting mechanism (not shown) is attached to the rolling roll, and it is preferable that the roll temperature can be arbitrarily adjusted.

(Element part of other manufacturing equipment)
In the above description, the molten metal supply unit, the casting roll unit, the conveyance unit, and the rolling roll unit have been described. However, in the manufacturing apparatus of the present invention, in addition to these element parts, a magnesium-based metal material supply / melting mechanism, obtained after rolling. A machining mechanism that performs processing such as cutting on a thin plate, a molding mechanism that performs molding such as in-line press, a temperature control mechanism that manages the temperature of the entire manufacturing apparatus, a control mechanism that controls each component, etc. It is preferable to provide it.

(Operational effect of the present embodiment)
According to the present invention, since the convex portion is formed on the surface of the plate material that enters the rolling process, the magnesium metal material of the convex portion is flattened and rolled in the periphery in the rolling step. This makes it possible to produce a plate material having a uniform metal structure or crystal arrangement and having no structure anisotropy.

  According to the present embodiment, it is possible to manufacture a magnesium-based metal sheet-shaped molded body having few surface defects such as cracks and excellent surface properties from a molten magnesium-based metal at a high speed and with a high yield.

[Third Embodiment]
As described above, in the first embodiment, it has been shown that a magnesium-based metal plate can be manufactured by casting a magnesium-based alloy using a roll having an uneven portion, but such a method is adopted. The magnesium-based metal plate produced in this way is excellent in surface properties and can be obtained with a substantially uniform plate thickness.
Moreover, the uneven | corrugated | grooved part of the roll surface used for casting is faithfully transcribe | transferred on the surface, and the board | plate material which has surface unevenness | corrugation is obtained, and it is visually excellent. This can be used as a decorative board without any processing on its surface. According to this method, it is possible to manufacture a plate material having a surface pattern from a molten magnesium-based metal with a small number of steps, and this is a manufacturing method that is extremely excellent in workability.

  In addition, in order to improve the quality as a decorative board, the surface can be further smoothed, plated, or painted.

[Modification of manufacturing equipment]
The magnesium-based metal thin plate of the present invention can be manufactured by using the above manufacturing apparatus, but in addition to the above-described ones, in the molten metal supply unit, the arrangement / number of casting rolls, the conveying device, etc. Can be employed.

Example 1
Using the apparatus shown in FIG. 1, a magnesium alloy (composition AM60) was melted at 640 ° C. and supplied between a pair of upper casting roll 5 and lower casting roll 6 made of a copper alloy having a roll diameter of 300 m. As this casting upper roll, hemispherical irregularities with a diameter of 1.7 mm were formed on the surface at a density of 25 pieces / cm ² . Using this casting roll, the gap between the rolls was 2 mm, and the casting was performed at a roll peripheral speed of 40 m / min and a load per unit length in the roll width direction of 0.6 kN / mm. The temperature of the molten metal when introduced into the casting roll was 612 ° C.
Defects such as cracks and spot cracks were not observed on the surface of the obtained thin plate.

(Example 2)
The magnesium alloy (composition AM60) was melted at 640 ° C. using the apparatus shown in FIG. 2 and supplied between a pair of upper casting roll 5 and lower casting roll 6 made of a copper alloy having a roll diameter of 300 m. As this casting upper roll, hemispherical uneven portions having a diameter of 2 mm were formed on the surface at a density of 20 pieces / cm ² . Using this casting roll, the gap between the rolls was 2 mm, and the casting was performed at a roll peripheral speed of 40 m / min and a load per unit length in the roll width direction of 0.6 kN / mm. The temperature of the molten metal when introduced into the casting roll was about 612 ° C. The cast plate material was conveyed using a conveyor belt conveyance device and rolled with a rolling roll to obtain a magnesium alloy plate material with a plate thickness of 2.5 mm. The rolling reduction was 30%.
The surface of the obtained thin plate had a smooth surface without cracks, spot cracks or surface roughness.

(Example 3)
As a casting upper roll, a casting roll having 8 spiral grooves each having a diameter of 0.5 mm on the surface is formed per roll width of 1 cm, the gap between the rolls is 2 mm, the peripheral speed of the roll is 40 m / min, and the roll width direction unit. A plate material was cast using the magnesium alloy melt of Example 1 with a load per length of 0.6 kN / mm. The temperature of the molten metal when introduced into the casting roll was about 612 ° C.
The surface of the obtained thin plate had a convex portion transferred faithfully, and was a plate material having excellent surface properties without cracks, spot cracks, or surface roughness.

(Comparative Example 1)
For comparison, a magnesium-based metal thin plate was produced by the same method as in Example 1 above using a casting roll having a smooth surface on which no irregularities were formed. In order to obtain a plate material having the same surface properties as in Example 1 by this method, it is necessary to control the temperature control of the twin rolls and the rate of change of the rotational speed of the twin rolls with an accuracy about five times that of the examples. there were. For this reason, the workability was remarkably reduced as compared with Example 1.

It is a schematic sectional drawing which shows the whole structure of the magnesium type metal thin plate manufacturing apparatus of 1st Embodiment. It is a perspective view which shows an example of the casting roll used by this invention. It is a partially expanded sectional view which shows an example of the casting roll used by this invention. It is a schematic sectional drawing which shows the whole structure of the magnesium-type metal thin plate manufacturing apparatus of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 41 ... Molten metal supply part 2, 42 ... Molten metal 3, 43 ... Molten tank 3a, 43a ... Molten metal outlet 4, 44 ... Casting roll part 5, 45 ... Upper casting roll 6, 46 ... Lower casting roll 7, 47 ... Plate material 45 ... Plate-shaped body conveyance part 46 ... Conveyance device 48 ... Rolling roll part

Claims (9)

In a method for producing a magnesium-based metal plate by supplying molten magnesium-based metal between at least a pair of rolls and casting it to a plate having a predetermined thickness,
A method for producing a magnesium-based metal sheet, wherein an uneven portion is formed on the surface of at least one of the at least one pair of rolls.   The depth of the uneven | corrugated | grooved part formed in the said roll surface is 0.01-3 mm, The manufacturing method of the magnesium type metal plate material of Claim 1 characterized by the above-mentioned.   The method for producing a magnesium-based metal sheet according to claim 1, wherein the uneven portion formed on the roll surface has a diameter of 0.01 to 5 mm.   2. The method for producing a magnesium-based metal sheet according to claim 1, wherein the uneven portions formed on the roll surface are formed with a distance between adjacent uneven portions of 0.5 to 100 mm. The uneven portion formed on the roll surface, method of manufacturing magnesium-based metal sheet according to claim 1, characterized in that it is formed at a density of from 0.01 to 400 pieces / cm ^2.
A casting process in which molten magnesium-based metal is supplied between at least a pair of first rolls and cast into a plate material having a predetermined thickness;
In the method for producing a magnesium-based metal thin plate, including a rolling step of applying pressure to at least a pair of second rolls and rolling the cast plate material to produce a magnesium-based metal thin plate having a predetermined thickness,
A method for producing a magnesium-based metal sheet, wherein an uneven portion is formed on the surface of at least one of the at least one pair of first rolls.
In a magnesium-based metal plate manufacturing apparatus comprising at least a casting roll portion for casting molten magnesium-based metal between at least a pair of rolls, applying pressure, and casting the solidified plate at a predetermined temperature,
An apparatus for producing a magnesium-based metal sheet, wherein at least one of the pair of rolls has an uneven portion formed on a surface thereof.
A cast roll portion for supplying molten magnesium-based metal between at least a pair of first rolls, applying pressure, and casting the plate material solidified to a predetermined temperature;
An apparatus for producing a magnesium-based metal sheet comprising at least a rolling roll unit for applying a pressure to the cast sheet material with at least a pair of second rolls and rolling to produce a magnesium-based metal sheet having a predetermined thickness In
An apparatus for producing a magnesium-based metal plate material, wherein at least one of the pair of first rolls has a concavo-convex portion formed on a surface thereof.
In the manufacturing method of the magnesium-based metal decorative board, supplying the molten magnesium-based metal between at least a pair of rolls and casting the plate material,
A method for producing a magnesium-based metal decorative board, wherein at least one of the pair of rolls is a roll having a concavo-convex portion formed on a surface thereof.

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