US20020060061A1

US20020060061A1 - Apparatus for manufacturing sheet metals through both sheet-casting process and continuous shear-straining process

Info

Publication number: US20020060061A1
Application number: US09/861,382
Authority: US
Inventors: Jae Lee; Hyun Seok; Jun Han; Young Chung; Ho Lee
Original assignee: Korea Advanced Institute of Science and Technology KAIST
Current assignee: Korea Advanced Institute of Science and Technology KAIST
Priority date: 2000-11-22
Filing date: 2001-05-18
Publication date: 2002-05-23
Also published as: JP2002153957A; KR20020039910A; KR100430065B1

Abstract

An apparatus for manufacturing sheet metals is disclosed. This apparatus primarily casts a liquid metal into an intermediate sheet through a sheet-casting process, and secondarily strains the intermediate sheet through a continuous shear-straining process, thus forming a desired high quality sheet metal having a high strength, a high formability and a specifically oriented texture without changing the thickness of the intermediate sheet or while slightly changing the thickness. This apparatus thus simplifies the process of manufacturing the sheet steels. The apparatus has a sheet-casting device used for primarily casting a liquid metal into an intermediate sheet, and a continuous shear-straining device used for continuously shear-straining the intermediate sheet from the sheet-casting device to form a desired sheet metal. The apparatus of this invention also has an intermediate device for pre-processing the intermediate sheet from the sheet-casting device prior to feeding the intermediate sheet to the continuous shear-straining device.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for manufacturing sheet metals and, more particularly, to an apparatus for manufacturing sheet metals by primarily casting a liquid metal into an intermediate sheet through a sheet-casting process and secondarily shear-straining the intermediate sheet through a continuous shear-straining process to form a desired high quality sheet metal having a high strength, a high formability and a specifically oriented texture, the apparatus thus consisting of a sheet-casting device for casting a liquid metal into an intermediate sheet and a continuous shear-straining device for continuously straining the intermediate sheet to form a desired sheet metal.

2. Description of the Prior Art

In the prior art, sheet metals have been typically produced through a rolling process or a casting process. In a conventional rolling process, a thick sheet, or a so-called “slab” formed by casting a liquid metal, passes through multistage rolling rolls to form a desired sheet metal. In a conventional casting process, a liquid metal is directly cast into a desired sheet metal prior to hardening the sheet metal.

However, the conventional rolling process for producing sheet metals is problematic in that it undesirably requires a lengthy rolling facility having a length ranging from several ten meters to several hundred meters. Such a lengthy rolling facility increases installation costs, and increases the processing time in addition to reducing productivity while producing sheet metals. This increases the production cost of the sheet metals.

On the other hand, the conventional casting process for producing sheet metals is advantageous in that it reduces the size of a sheet producing facility in addition to reducing the processing time while producing the sheet metals, thus finally decreasing the production cost of the sheet metals. However, this casting process is problematic in that its resulting sheet metals are inferior in their properties as the sheet metals have low strength, low hardness, low elongation ratio, and low formability.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an apparatus for manufacturing sheet metals, which primarily casts a liquid metal into an intermediate sheet through a sheet-casting process, thus greatly simplifying the process of producing the sheet metals, and which secondarily strains the intermediate sheet through a continuous shear-straining process, thus forming a desired high quality sheet metal having high strength, high formability and a specifically oriented texture without changing the thickness of the intermediate sheet or while slightly changing said thickness, and which simplifies the process of manufacturing the sheet steels.

In order to accomplish the above object, the present invention provides an apparatus for manufacturing sheet metals, comprising a sheet-casting device used for primarily casting a liquid metal into an intermediate sheet, and a continuous shear-straining device used for continuously shear-straining the intermediate sheet from the sheet-casting device, thus forming a desired sheet metal.

The sheet metal manufacturing apparatus of this invention also comprises an intermediate device for pre-processing the intermediate sheet from the sheet-casting device prior to feeding the intermediate sheet to the continuous shear-straining device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [0010]
FIG. 1 is a view, schematically showing the construction of a sheet metal manufacturing apparatus consisting of a sheet-casting device and a continuous shear-straining device in accordance with the primary embodiment of the present invention; [0011]
FIGS. 2[0012] a, 2 b, 2 c to 2 d are views, schematically showing the arrangements of two rolls of a double roll-type casting device used as the sheet-casting device of the sheet metal manufacturing apparatus in accordance with different modifications of the primary embodiment of this invention;
FIG. 3 is a view, showing the construction of a chained block-type casting device used as the sheet-casting device in accordance with the second embodiment of the present invention; [0013]
FIG. 4 is a view, showing the construction of a belt-type casting device used as the sheet-casting device in accordance with the third embodiment of the present invention; [0014]
FIGS. 5[0015] a and 5 b are views, showing the construction of a melt drag-type casting device used as the sheet-casting device in accordance with the fourth embodiment of the present invention;
FIG. 6 is a view, showing the construction of a single roll-type casting device used as the sheet-casting device in accordance with the fifth embodiment of the present invention; [0016]
FIG. 7 is a view, showing the construction of a mold-type casting device used as the sheet-casting device in accordance with the sixth embodiment of the present invention; [0017]
FIGS. 8[0018] a, 8 b and 8 c are views, showing the construction of an electromagnetic agitator, a mechanical vibrator and an ultrasonic vibrator, each of which is installed in the sheet-casting device in accordance with an embodiment of the present invention so as to agitate or vibrate the liquid metal before the liquid metal reaches the sheet-casting device;
FIGS. 9[0019] a and 9 b are views, showing the arrangements of the sheet-feeding unit and mold unit of the continuous shear-straining device in accordance with different embodiments of the present invention;
FIG. 10 is a view, showing the arrangement of the sheet-feeding unit and mold unit of the continuous shear-straining device in accordance with another embodiment of the present invention; [0020]
FIGS. 11[0021] a, 11 b and 11 c are views, showing the construction of the sheet-feeding units of the continuous shear-straining device in accordance with further embodiments of the present invention;
FIGS. 12[0022] a and 12 b are views, showing the construction of continuous shear-straining devices provided with a sheet scalping function in accordance with another embodiment of the present invention;
FIG. 13 is a graph, showing the Vickers hardness as a function of the reduction ratio for a sheet metal produced by the apparatus of the present invention and a sheet metal produced through the conventional rolling process; and [0023]
FIG. 14 is a graph, showing the formability index as a function of the angle of the rolling direction for a sheet metal produced by the apparatus of the present invention.[0024]

DETAILED DESCRIPTION OF THE INVENTION

Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. [0025]
FIG. 1 is a view, schematically showing the construction of a sheet metal manufacturing apparatus consisting of a sheet-casting device and a continuous shear-straining device in accordance with the primary embodiment of the present invention. [0026]
As shown in the drawing, the apparatus for manufacturing sheet metals according to the primary embodiment of the present invention has a double roll-[0027] type casting device 10 used as a sheet-casting device for primarily casting a liquid metal into an intermediate sheet 100. This apparatus also has a continuous shear-straining device 40 used for continuously shear-straining the intermediate sheet 100, thus forming a desired sheet metal.
In FIG. 1, the [0028] reference numeral 30 denotes an intermediate device for pre-processing the intermediate sheet 100 from the double roll-type casting device 10 prior to feeding the intermediate sheet 100 to the continuous shear-straining device 40. In a first modification of the primary embodiment of this invention, the intermediate device 30 may comprise a roller guider 32 consisting of a plurality of guide rollers as shown by portion “A” of FIG. 1. This roller guider 32 allows the intermediate sheet 100 from the roll-type casting device 10 to pass over the rollers so as to simply and directly feed the intermediate sheet 100 to the continuous shear-straining device 40.
In a second modification of the primary embodiment, the [0029] intermediate device 30 may comprise a sheet-winding drum 34 as shown by portion “B” of FIG. 1. The sheet-winding drum 34 winds the intermediate sheet 100 from the double roll-type casing device 10 on its winding roll prior to feeding said intermediate sheet 100 to the continuous shear-straining device 40.
In a third modification of the primary embodiment, the [0030] intermediate device 30 may comprise a rolling machine 36 as shown by portion “C” of FIG. 1. This rolling machine 36 hot-rolls or cold-rolls the intermediate sheet 100 from the roll-type casting device 10 prior to feeding the intermediate sheet 100 to the continuous shear-straining device 40.
In a fourth modification of the primary embodiment, the [0031] intermediate device 30 may comprise a heating or cooling unit 38 as shown by portion “D” of FIG. 1. This heating or cooling unit 38 heats or cools the intermediate sheet 100 from the roll-type casting device 10 prior to feeding the intermediate sheet 100 to the continuous shear-straining device 40.
In the sheet metal manufacturing apparatus of the present invention, the [0032] intermediate device 30 is installed at a position between the sheet-casting device and the continuous shear-straining device. In addition, it is possible to use at least one of the above-mentioned guide rolls 32 of portion “A”, sheet-winding drum 34 of portion “B”, rolling machine 36 of portion “C” and heating or cooling unit 38 of portion “D” as the intermediate device 30.
FIGS. 2[0033] a, 2 b, 2 c and 2 d are views, showing the arrangements of two rolls of the double roll-type casting device 10 in accordance with different modifications of the primary embodiment of this invention.
As shown in the drawings, the double roll-[0034] type casting device 10 of the present invention comprises two rolls 11 and 12 provided with a cooling unit. In such a case, the rolling direction of the roll-type casting device 10 may be changed in accordance with the arrangement of the two rolls 11 and 12.
That is, the two [0035] rolls 11 and 12 of the double roll-type casting device 10 may be arranged to form a vertical rolling direction, with a liquid metal moving in the vertical inlet downward into the nip of the two rolls 11 and 12 as shown in FIG. 2a. In another modification, the two rolls 11 and 12 of the double roll-type casting device 10 may be arranged to form another type of vertical rolling direction, with the liquid metal moving in the vertical inlet upward into the nip of the two rolls 11 and 12 as shown in FIG. 2b. In a further modification, the two rolls 11 and 12 may be arranged to form a horizontal rolling direction, with the liquid metal moving in the horizontal inlet into the nip of the two rolls 11 and 12 as shown in FIG. 2c. In still another modification, the two rolls 11 and 12 may be arranged to form a diagonal rolling direction, with the liquid metal moving in the diagonal inlet upward into the nip of the two rolls 11 and 12 as shown in FIG. 2d. In addition, the two rolls 11 and 12 of the double roll-type casting device 10 may be arranged to form another type of diagonal rolling direction (not shown), with the liquid metal moving in the diagonal inlet downward into the nip of the two rolls 11 and 12.
In accordance with the second embodiment of the present invention, the sheet-casting device may comprise a chained block-[0036] type casting device 10A, which consists of two block chains 13 each formed by connecting a plurality of blocks together into a rotatable block chain 13 as shown in FIG. 3. Each of the two block chains 13 is provided with a cooling unit (not shown). It is particularly preferred to use this chained block-type casting device 10A for producing thick sheet metals since the device 10A more quickly cools the intermediate sheet 100 and increases the length of its sheet hardening section in comparison with the double roll-type casting device 10 of FIGS. 2a to 2 d.
In accordance with the third embodiment of the present invention, the sheet-casting device may comprise a belt-[0037] type casting device 10B, which consists of two belts 15 each wrapped around two rolls 14 as shown in FIG. 4. Each of the two belts 15 is provided with a cooling unit (not shown).
In accordance with the fourth embodiment of the present invention, the sheet-casting device may comprise a melt drag-[0038] type casting device 10B, in which liquid metal is dragged by a rotating roll 16 to form an intermediate sheet 100 as shown in FIG. 5a. This melt drag-type casting device 10B is advantageous in that it more quickly produces a thin intermediate sheet 100 in comparison with the double roll-type casting device 10. In a modification of the fourth embodiment of the present invention, a subsidiary roll 17 may be installed above the main roll 16 as shown in FIG. 5b so as to improve the smoothness of the upper surface of the intermediate sheet 100.
In addition, the fifth embodiment of the present invention provides a single roll-[0039] type casting device 10D as the sheet-casting device as shown in FIG. 6. This single roll-type casting device 10D consists of one roll 18, provided with a cooling unit (not shown), different from the double roll-type casting device 10.
FIG. 7 shows the construction of a continuous mold-[0040] type casting device 10E used as the sheet-casting device in accordance with the sixth embodiment of the present invention. This continuous mold-type casting device 10E consists of a cold mold 20 provided with an intermediate sheet discharging slit 19 at its bottom wall.
In the present invention, an [0041] electromagnetic agitator 20 a of FIG. 8a may be installed in each of the sheet-casting devices 10, 10A, 10B, 10C, 10D and 10E of FIGS. 1 to 7 so as to agitate the liquid metal before the liquid metal reaches the sheet-casting device. Alternatively, a mechanical vibrator 21 of FIG. 8b may be installed in each of the sheet-casting devices 10, 10A, 10B, 10C, 10D and 10E of FIGS. 1 to 7 so as to mechanically vibrate the liquid metal before the liquid metal reaches the sheet-casting device. As a further alternative, an ultrasonic vibrator 22 of FIG. 8c may be installed in each of the sheet-casting devices 10, 10A, 10B, 10C, 10D and 10E of FIGS. 1 to 7 so as to vibrate the droplets of the liquid metal using ultrasonic waves before the liquid metal reaches the sheet-casting device. When the sheet-casting device of this invention is provided with one of the above-mentioned agitator 20 a, mechanical vibrator 21 or ultrasonic vibrator 22, it is possible to make a spherical fine texture from the liquid metal and prevent formation of undesired segregations, thus finally improving the mechanical properties of the intermediate sheet 100.
FIGS. 9[0042] a and 9 b are views, showing the arrangements of the sheet-feeding unit and mold unit of the continuous shear-straining device in accordance with different embodiments of the present invention.
In the embodiment of FIG. 9[0043] a, the continuous shear-straining device 40A comprises a sheet-feeding unit 41 consisting of two rotating rolls. A mold unit 42, consisting of upper and lower molds and having a shear-straining passage, is assembled with the sheet-feeding unit 41. This mold unit 42 is used for shear-straining the intermediate sheet 100 to form a desired sheet metal. In the continuous shear-straining device 40B according to the embodiment of FIG. 9b, the sheet-feeding unit 41 and the mold unit 42 are arranged such that the intermediate sheet 100 is initially fed to the mold unit 42 after the sheet 100 moves along the outside surface of one roll of the sheet-feeding unit 41 to reach a position on the roll spaced apart from the outlet of the nip of said rolls. The arrangement of FIG. 9b preferably increases the frictional force between the sheet 100 and the sheet-feeding device 41.
FIG. 10 is a view, showing the arrangement of the sheet-feeding [0044] unit 41 and mold unit 42 of the continuous shears-training device in accordance with another embodiment of the present invention. In this embodiment, the continuous shear-straining device 40C comprises a sheet-feeding unit 41 consisting of one or two rotating rolls. A mold unit 42 is assembled with the sheet-feeding unit 41, and is used for shear-straining the intermediate sheet 10 while separating the sheet 100 from the sheet-feeding unit 41, thus form a desired sheet metal.
Different from the continuous shear-straining [0045] devices 40A and 40B of FIGS. 9a and 9 b, each of which is designed to shear-strain the intermediate sheet 100 within the mold unit 42, the continuous shear-straining device 40C of FIG. 10 is designed to shear-strain the sheet 100 at the inlet of the mold unit 42.
FIGS. 11[0046] a, 11 b and 11 c are views, showing the construction of the sheet-feeding units of the continuous shear-straining device 40A, 40B or 40C in accordance with further embodiments of the present invention. In the embodiment of FIG. 11a, the sheet-feeding unit for feeding the sheet 10 to the mold unit 42 comprises a belt-type feeding unit 41A. This belt-type unit 41A consists of two belts 44, each of which is wrapped around two rolls 43. In the embodiment of FIG. 11b, the sheet-feeding unit comprises a roll-type feeding unit 41B. This roll-type unit 41B consists of a plurality of identical rolls 45, which are regularly arranged opposite each other to form a plurality of pairs of rolls and feed the sheet 100 into the mold unit 42 through the nips between the pairs of rolls 45. In the embodiment of FIG. 11c, the sheet-feeding unit comprises a roll-type feeding unit 41C, which consists of a plurality of rolls 46. These rolls 46 have different sizes, and are arranged specifically to feed the intermediate sheet 100 to the mold unit 42.
In the present invention, the circumferential surface of each roll of the sheet-feeding [0047] unit 41, 41A, 41B or 41C may have an uneven surface capable of increasing the frictional force between the sheet 100 and the rolls of the sheet-feeding unit.
FIGS. 12[0048] a and 12 b are views, showing the construction of continuous shear-straining devices provided with a sheet scalping function in accordance with still another embodiment of the present invention. In each of the continuous shear-straining devices of FIGS. 12a and 12 b, a predetermined gap is formed in the lower mold 42 or at a position between the sheet-feeding unit 41 and the mold unit 42 to scalp the surface of the sheet 100 during a continuous shear-straining process. That is, when the sheet 100 is shear-strained by the mold unit 42 with the bent passage having an angle N, a plurality of shells are formed on the surface of the sheet 100 and so it is necessary to change the shells into chips prior to scalping the surface of the sheet 100 to discharge the chips from the sheet 100 to the outside through the gap. Such a scalping process improves the surface properties of the shear-strained sheet 100. The gap formed in the mold unit 42 also increases the frictional force between the lower surface of the sheet 100 and the mold unit 42, thus finally allowing the sheet 100 to be uniformly shear-strained in a set thickness of the sheet 100.
FIG. 13 is a graph, showing the Vickers hardness as a function of the reduction ratio for 1050 aluminum alloy sheet produced by the apparatus of this invention and a sheet metal produced through the conventional rolling process. As shown in the graph, the 1050 aluminum alloy sheet, which was produced by shear-straining an intermediate sheet using a [0049] mold unit 42 having a one time bent passage angle of 120°, has a Vickers hardness ranging from 60 Hv (200 g) to 70 Hv (200 g). Such hardness of the sheet metal of this invention can be expected from a sheet metal produced through a conventional rolling process with a reduction ratio of 90% or more.
FIG. 14 is a graph, showing the formability index (R-value) as a function of the angle to the rolling direction for the 1050 aluminum alloy sheet produced by the apparatus of the present invention. The 1050 aluminum alloy sheet was produced by shear-straining an intermediate sheet using the [0050] mold unit 42 having a one time bent passage angle of 120° in the same manner as that described above. As shown in the graph, the R-value of the 1050 aluminum alloy sheet ranges from about 1.0 to about 2.5 in the set thickness of the sheet. Such an R-value is almost equal to that expected from a sheet steel having high formability.
The sheet manufacturing apparatus of the present invention may be preferably used for producing sheet metals having a thickness of about 0.5 mm or less˜10 mm or more. [0051]
As described above, the present invention provides an apparatus for manufacturing sheet metals. This apparatus primarily casts a liquid metal into an intermediate sheet through a sheet-casting process, and secondarily strains the intermediate sheet through a continuous shear-straining process, thus forming a desired high quality sheet metal having a high strength, a high formability and a specifically oriented texture. When the apparatus of this invention is used for producing aluminum sheets, it is possible to improve the formability of the aluminum sheets even though aluminum intrinsically has a low formability. In addition, this apparatus preferably reduces the production cost of the aluminum sheets. Therefore, the sheet manufacturing apparatus of this invention can entirely solve the problems experienced in the conventional processes of manufacturing aluminum sheets caused by low formability and high production costs. When the aluminum sheets having a high formability produced by the apparatus of this invention are used in the chassis of automobiles, it is possible to reduce the total weight of an automobile by about 50%. In addition, this apparatus reduces the production cost of sheet metals by about 20% in comparison with conventional apparatuses. [0052]
Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. [0053]

Claims

What is claimed is:

1. An apparatus for manufacturing sheet metals, comprising:

a sheet-casting device used for primarily casting a liquid metal into an intermediate sheet; and

a continuous shear-straining device used for continuously shear-straining said intermediate sheet from the sheet-casting device, thus forming a desired sheet metal.

2. The apparatus according to claim 1, further comprising an intermediate device used for pre-processing the intermediate sheet from the sheet-casting device prior to feeding said intermediate sheet to the continuous shear-straining device.

3. The apparatus according to claim 1, wherein said sheet-casting device comprises a double roll-type casting device consisting of two rotating rolls arranged to form a nip between them, with a cooling unit provided in said double roll-type casting device.

4. The apparatus according to claim 1, wherein said sheet-casting device comprises a chained block-type casting device consisting of two block chains each formed by connecting a plurality of blocks together into a rotatable block chain, with a cooling unit provided in said chained block-type casting device.

5. The apparatus according to claim 1, wherein said sheet-casting device comprises a belt-type casting device consisting of two belts each wrapped around two rolls, with a cooling unit provided in said belt-type casting device.

6. The apparatus according to claim 1, wherein said sheet-casting device comprises a melt drag-type casting device consisting of a rotating roll dragging the liquid metal to form the intermediate sheet.

7. The apparatus according to claim 1, wherein said sheet-casting device comprises a single roll-type casting device consisting of one roll, with a cooling unit provided in said single roll-type casting device.

8. The apparatus according to any one of claims 1 to 7, wherein either an electromagnetic agitator, a mechanical vibrator or an ultrasonic vibrator is installed in said sheet-casting device so as to improve mechanical properties of the intermediate sheet.

9. The apparatus according to claim 1, wherein said continuous shear-straining device comprises:

a mold unit consisting of upper and lower molds and having a shear-straining passage bent at a predetermined angle, said mold unit thus being used for shear-straining the intermediate sheet to form the sheet metal; and

a sheet-feeding unit used for feeding said intermediate sheet to said mold unit.

10. The apparatus according to claim 9, wherein said sheet-feeding unit and said mold unit are arranged such that the intermediate sheet is initially fed to the mold unit after the intermediate sheet moves along the surface of said sheet-feeding unit to a predetermined position, thus increasing frictional force between the intermediate sheet and the sheet-feeding device.

11. The apparatus according to claim 1, wherein said continuous shear-straining device comprises:

a sheet-feeding unit; and

a mold unit used for shear-straining the intermediate sheet while separating said intermediate sheet from the sheet-feeding unit, thus forming the sheet metal.

12. The apparatus according to claim 9, wherein said sheet-feeding unit is selected from the group consisting of a first roll-type feeding unit having two rolls, a belt-type feeding unit having two belts each wrapped around two rolls, a second roll-type feeding unit having a plurality of identical rolls regularly arranged opposite each other to form a plurality of pairs of rolls, and a third roll-type feeding unit having a plurality of different-sized rolls.

13. The apparatus according to claim 12, wherein each of the rolls of said sheet-feeding unit is uneven on its circumferential surface so as to increase frictional force between the intermediate sheet and the roll of the sheet-feeding unit.

14. The apparatus according to claim 9, wherein a predetermined gap is formed in said mold unit or at a position between the sheet-feeding unit and the mold unit to scalp the surface of said intermediate sheet during a continuous shear-straining process.

15. The apparatus according to claim 2, wherein said intermediate device is selected from the group consisting of a roller guider, a sheet-winding drum designed to wind the intermediate sheet on its winding roll, a rolling machine designed to hot-roll or cold-roll the intermediate sheet, and a heating or cooling unit designed to heat or cool the intermediate sheet.