JPH08243701A - Production of cast slab for rolling - Google Patents

Abstract

PURPOSE: To improve economical efficiency by pouring molten metal into a mold, passing through the mold while cooling to produce a cast block and thereafter, rolling with flattening rollers, in a producing method of a cast slab for rolling. CONSTITUTION: The molten metal M is received into a molten metal trough 1 and poured into the mold 3 from the molten metal trough/through a pouring cylinder 2. The molten metal M is formed to the same shape as a flat surface shape forming a rectangular shape of the mold 3 and descended and passed through the mold 3. The molten metal M passed through the mold 3 is cooled by contacting with cooling water W forming a wall by spraying from many cooling water spraying holes 5 at the lower side of the mold 3. By this method, the molten metal M is gradually solidified toward the inner part from the surface part even after passing through the mold 3, and finally, the molten metal becomes the whole solid phase and changes into the cast block forming the rectangular cross section. A receiving ladle 6 is arranged just below the mold 3 and the descended cast block is received. In the process for descending the cast slab S continuing the cast block obtd. by solidifying the whole molten metal M, the cast slab S is rolled with one pair of the flattening rollers 7 to flatten the surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rolling ingot slab in which a molten metal is put into a mold and cooled to form an ingot, and the ingot is continuously drawn to produce a rolling ingot slab. .

[0002]

2. Description of the Related Art A direct cooling continuous casting method has been adopted for producing a rolling slab made of an aluminum alloy. In this direct cooling type continuous casting method, a molten metal obtained by melting a metal material in a melting furnace is sent from a holding furnace to a casting machine through a molten metal treatment device, and a casting machine produces an ingot slab from the molten metal.

In a casting machine, the molten metal is poured from a gutter into a mold through a barrel. Cooling water is circulated inside the mold to be cooled, and the cooling water is jetted from the lower part of the mold to the outside. Therefore, the molten metal is cooled by the wall of the mold and formed into the same shape as the plan shape of the mold and passes through the mold.Furthermore, the molten metal is cooled by the cooling water ejected downward from the mold to be solidified and cast. It becomes a lump. This ingot is received by a pedestal that can move up and down, and as the pedestal descends, it is continuously formed into a slab shape to obtain an ingot slab.

The ingot slab manufactured by the direct cooling type continuous casting method has its surface cut by a chamfering machine (scalper) and then hot rolled into a form such as a strip or plate. The cutting with this chamfering machine is intended to scrape off the defective structure layer on the surface portion of the ingot slab and remove the uneven portion formed on the surface portion of the ingot slab.

That is, in the direct cooling type continuous casting, when the molten metal is passed through a mold to be cooled to produce an ingot slab, a bad structure layer such as a molten slag is formed on the surface of the ingot slab. This defective tissue layer is unnecessary as a product and must be removed.

Further, in the direct cooling continuous casting, the molten metal does not uniformly solidify and shrink over the entire cross section of the ingot slab,
Partial variations in solidification shrinkage occur in the cross section of the ingot slab. For this reason, the entire cross section of the ingot slab is not uniform, and unevenness is partially generated. If the ingot slab having such irregularities is rolled, good rolling cannot be performed.

Therefore, in addition to the conventional direct cooling continuous casting, in addition to cutting the surface portion of the ingot slab with a chamfering machine to scrape off the defective structure layer on this surface portion, unevenness existing on the surface portion Parts are eliminated and the entire surface is made uniform.

[0008]

However, in general, the depth dimension of the uneven portion generated in the ingot slab due to the variation in the solidification shrinkage of the molten metal is larger than the thickness dimension of the defective structure layer. Therefore, in order to remove the irregularities from the surface of the ingot slab, the surface of the ingot slab must be cut with a cutting thickness larger than the thickness of the defective structure layer. Therefore, the cutting thickness of the surface portion of the ingot slab is large, and the number of times of cutting the surface portion of the ingot slab by the chamfering machine (scalper) is increased in order to secure this large cutting thickness.

Further, the fact that the cutting thickness of the surface portion of the ingot slab is large means that the portion of the ingot slab that cannot be supplied to the final rolled product increases, and in this respect, it can be said that the economical efficiency is poor.

The present invention has been made in view of the above circumstances. In the direct cooling type continuous casting method, the portion of the lump which has passed through the mold is solidified to be a solid phase, which is rolled to solidify. An object of the present invention is to provide a method for manufacturing an ingot slab for rolling, which can flatten the uneven portion generated in the ingot and reduce the cutting thickness of the surface portion after casting.

[0011]

Means for Solving the Problems In order to achieve the above-mentioned object, a method for producing a rolling ingot slab according to the present invention is as follows. Are continuously formed to obtain an ingot slab, and then the manufactured slab is rolled by a pair of flattening rollers.

[0012]

The molten metal is poured into the mold and cooled by the wall of the mold. As a result, the molten metal starts to solidify from the surface to the inside, passes through the mold after being shaped into the same shape as the plan shape of the mold. The molten metal that has passed through the mold gradually solidifies from the surface portion toward the inside, and becomes an ingot that entirely forms a solid phase portion. Then, the ingot is received by a pedestal that can move up and down, and as the pedestal descends, the ingot is continuously formed to obtain an ingot slab.

However, in the course of solidification of the molten metal, the entire cross section of the molten metal cannot be uniformly solidified and shrunk, and the solidified shrinkage partially varies. As a result, the entire cross section of the ingot obtained by solidifying the entire molten metal is not uniform, and uneven portions are partially formed.

In the method of the present invention, the ingot slab obtained as described above is passed between a pair of flattening rollers. By passing the ingot slab through the pair of flattening rollers,
The concavo-convex portion existing on the surface portion of the ingot slab is compressed and deformed to flatten the surface of the ingot slab.

Therefore, since there is no uneven portion on the surface of the ingot slab, in the step of cutting the surface of the ingot slab after casting, only the defective structure layer existing on the surface of the ingot slab is scraped off. The cutting thickness may be the thickness of the poor texture layer. As a result, the cutting thickness becomes smaller and the number of times of cutting the surface portion of the ingot slab by the chamfering machine is reduced as compared with the case where the surface portion of the ingot slab is uneven as in the conventional case. Further, since the cutting thickness is reduced, the portion of the ingot slab that cannot be supplied to the final rolled product is reduced, and the economical efficiency is improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for manufacturing an ingot slab for rolling of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a mold showing the method of the present invention, and FIG. 2 is a sectional view of the mold showing the method of the present invention. First, a metal material, for example, an aluminum alloy material is melted in a melting furnace to obtain a molten metal, and the molten metal is processed by a molten metal processing device (filter) through a holding furnace.

Next, as shown in FIG.
Then, it is poured into the casting mold 3 from the gutter 1 through the casting pipe 2. As shown in FIGS. 1 and 2, the mold 3 has a rectangular frame shape and is arranged horizontally. As shown in FIG. 2, a cooling water passage 4 is formed as a space inside the mold 3, and a large number of cooling water injection ports 5 communicating with the cooling water passage 4 are arranged in the lower part of the inner circumference of the mold 3 in the circumferential direction of the mold 3. Form.

Then, the cooling water W is supplied from a water supply source (not shown) to the cooling water passage 4 inside the casting mold 3 so as to flow therein.
The cooling water W flows over the entire circumference of the mold 3 to cool the wall of the mold 3 over the entire circumferential direction. Further, the cooling water W is jetted downward from a large number of cooling water jet ports 5 of the mold 3 to form a cooling water wall surrounding the entire circumferential direction on the lower side of the mold 3.

The molten metal M is poured into a rectangular inner space surrounded by the mold 3. The poured molten metal M touches the wall of the mold 3 and is cooled, and the surface portion is solidified. As a result, the molten metal M is formed into the same shape as the rectangular planar shape of the mold 3 and descends to pass through the mold 3. Further, the molten metal M that has passed through the mold 3 is cooled by touching the cooling water w that forms a wall by being sprayed from a large number of cooling water spray ports 5 on the lower side of the mold 3. As a result, the molten metal M gradually solidifies from the surface portion toward the inside even after passing through the mold 3, and finally becomes the whole solid phase and changes into an ingot having a rectangular cross section.

A pedestal 6 is provided right below the mold 3 to receive the ingot that has descended. The cradle 6 is moved up and down by a cylinder (not shown), receives the ingot, and moves down by driving the piston rod 7. As the pedestal 6 descends, ingots are continuously formed to manufacture the ingot slab S.

Here, in the process in which the molten metal M which is a liquid phase is solidified and is transferred to the ingot which is a solid phase, the entire cross section of the molten metal M cannot be solidified uniformly, and the solidification shrinkage partially varies.
As a result, as shown in FIG. 4, the cross section of the ingot is not entirely uniform, and uneven portions 11 are partially formed. The uneven portion 11 of the ingot slab S occurs on a wide surface of the ingot having a rectangular cross section. In the figure, 12 is a defective structure layer formed on the surface of the ingot. Also, the virtual line in the figure is the shape cut by a chamfer.

In the present invention, the ingot slab S is rolled by the pair of flattening rollers 7 in the process of descending the ingot slab S in which the ingot obtained by solidifying the entire molten metal M descends. Make the surface flat. That is, a pair of flattening rollers 7 is arranged on the lower side of the mold 3 along the path of movement of the ingot so as to sandwich the wide surface of the ingot slab S. The position where the pair of flattening rollers 7 is provided is a point after the entire melt M that has passed through the mold 3 in the moving path of the ingot slab S is solidified and transferred to the ingot which is the solid phase.

The pair of flattening rollers 7 are arranged to be positioned by a rolling device (not shown) according to the rolling dimension of the pair of flattening rollers 7, and to be rotationally driven by a rotary driving device (not shown). Has become. The amount of reduction of the pair of flattening rollers 7 with respect to the ingot (thickness inlet thickness-thickness outlet thickness) is a size that can remove the uneven portion 11 generated in the ingot slab S. For example, it is about 1/100 of the thickness of the ingot.

Then, when the pedestal 6 moves up to receive the ingot, it passes through the pair of flattening rollers 7, and when the pedestal 6 that receives the ingot descends, it passes through the pair of flattening rollers 7. In order to do so, the pair of flattening rollers 7 are opened to allow passage of the pair of flattening rollers 7.

After the pedestal 6 which has received the ingot slab S descends and passes through the pair of flattening rollers 7, the ingot slab S is cast with a reduction amount required by the pair of flattening rollers 7. It moves to a position where the uneven portion 11 generated in the lump can be removed. After that, as the pedestal 6 descends, the ingot slab S successively passes between the pair of flattening rollers 7 from the lower end.

As a result, the wide surface of the ingot slab S is pressed by the pair of flattening rollers 7 to roll the ingot slab S. At this time, as shown in FIG. 3, the concavo-convex portion 11 existing on the surface of the wide surface of the ingot slab S is pressed by the pair of flattening rollers 7 to be compressed and deformed to be flat. The uneven portion 11 on the surface of the wide surface of S is removed, and the surface of the wide surface of the ingot slab S is flattened.

Thereafter, the surface portion of the ingot slab S is cut by a chamfering machine to the cutting position of the imaginary line shown in FIG. 3 to scrape off the defective texture layer 12 formed on the surface portion. At this time, since the uneven portion does not exist on the surface portion of the ingot slab S, in the step of cutting the surface portion of the ingot slab S after casting, only the defective structure layer 12 existing on the surface portion of the ingot slab S is scraped off. The cutting thickness A may be almost the thickness of the defective structure layer 12. As a result, the ingot slab S is BI-cut when the uneven surface portion is present as in the conventional ingot slab. The cutting thickness A becomes smaller than the thickness B, and the number of times the surface portion of the ingot slab S is cut by the chamfering machine also decreases. Moreover, since the ingot slab S has a small cutting thickness,
The portion of the ingot slab S that cannot be supplied to the final rolled product is reduced and the economical efficiency is improved.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways. The flattening with the flattening roller for the ingot slab is not limited immediately after the ingot is manufactured by the mold as shown in the above-described examples, and the process is performed until the ingot slab is cut by the chamfering machine. If it is good.

Further, in the above-mentioned embodiment, the flat surface of the ingot slab having a rectangular cross section is pressed by the flattening roller to flatten it. It is also possible to press the narrow surface to flatten it.

[0030]

As described above, according to the method for producing the ingot slab for rolling of the present invention, the molten metal is put into the mold and passed through the mold while being cooled, and the ingot is continuously formed. Form the ingot slab, and then roll the manufactured slab with a pair of flattening rollers to compress the irregularities formed on the surface of the ingot slab with the flattening roller when the molten metal condenses during casting. It can be deformed to flatten the surface of the ingot.

Therefore, according to the method of the present invention, since there is no uneven portion on the surface of the ingot slab, it exists on the surface of the ingot slab in the step of cutting the surface of the ingot slab after casting. The defective tissue layer is only scraped off, and the cutting thickness may be the thickness of the defective tissue layer.

As a result, the ingot slab obtained by the method of the present invention has a smaller cutting thickness as compared with the conventional case where the surface portion has irregularities, and the ingot slab is produced by the chamfering machine. The number of times the surface of the slab is cut is also reduced. Further, since the cutting thickness is reduced, the portion of the ingot slab that cannot be supplied to the final rolled product is reduced, and the economical efficiency is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a method for manufacturing an ingot slab for rolling of the present invention.

FIG. 2 is an explanatory view showing the same embodiment.

FIG. 3 is a cross-sectional view showing an ingot slab for rolling after being flattened by a flattening roller.

FIG. 4 is a sectional view showing an ingot slab for rolling before being flattened in a comparative example.

[Explanation of symbols]

 3 ... Mold, 6 ... Cradle, 7 ... Flattening roller, M ... Molten metal, S ... Casting slab.

Claims (1)

[Claims] 1. An ingot slab is formed by continuously pouring molten metal into a mold while cooling the molten metal and passing through the mold to obtain an ingot slab. Then, the ingot slab is paired with a pair of flattening rollers. A method for manufacturing an ingot slab for rolling, which comprises rolling with an ingot.