CASTING-ROLLING METHOD BASED ON MULTI-LAYER HETEROGENEOUS COMPOSITE ROLL SLEEVE AND APPARATUS THEREOF

TECHNICAL FIELD

[0001]The present disclosure relates to the technical field of advanced metal functional material casting-rolling formation, and specifically to a casting-rolling method based on a multi-layer heterogeneous composite roll sleeve and an apparatus thereof.

BACKGROUND

[0002]Twin-roll casting-rolling technology is a near-net-shape forming technology that integrates rapid solidification and hot rolling deformation. Its process principle is defined as pouring liquid metal from a tundish or a feeding nozzle into a gap between two counter-rotating cooling rolls. The liquid metal solidifies and crystallizes between the two rolls. Under a rolling force generated by the two rolls, it undergoes a certain amount of plastic deformation to directly produce metal strip. This technology has significant advantages such as a short process, high efficiency, and low cost, making it a key development direction in the industry.

[0003]At present, the technology is relatively mature and highly industrialized in the casting-rolling of non-ferrous metals such as aluminum and magnesium. For example, aluminum alloy plates and strips have been industrially produced by a casting-rolling method. However, due to the limited cooling capacity of the casting-rolling rolls, only some alloy grades with low alloy element content and narrow solidification ranges, such as series 1, 3, 8, 5, and 6, can be produced, and the casting-rolling speed is relatively low, only 1.2-2.4 m/min. Therefore, for the casting-rolling process of monometallic metals, it has become an urgent key issue to enhance the cooling capacity of the casting-rolling rolls to increase the casting-rolling speed and expand the range of castable alloy grades.

[0004]Nowadays, with increasing maturity of casting-rolling technology, the requirements for the configuration of casting-rolling plate are also becoming higher and higher. Casting and rolling strips often suffer from defects such as segregation due to uneven distribution of alloy elements in a width direction of the plate, which can seriously affect the formation in subsequent processes. Existing casting-rolling machines almost rely on initial roll profile of the casting-rolling rolls to control the plate shape. However, this method is greatly affected by thermal convexity and wear of the casting-rolling rolls, thereby increasing the difficulty of plate shape control and resulting in poor plate shape quality.

[0005]Based on twin-roll casting-rolling technology, research has been conducted on solid-liquid casting-rolling composite processes for layered metal composite materials, such as the towing type, overflow type twin-roll casting-rolling method, casting-rolling composite process with a scraper, differential diameter casting-rolling composite process, multi-stage series, etc., and successfully prepared two-layer, three-layer, and five-layer composite strips. However, there is still an important problem that has not been solved in the current solid-liquid casting-rolling composite process for layered metal composite materials. In the process of the solid-liquid casting-rolling composition, the feeding of the solid base metal strip forms an asymmetric solid-liquid casting-rolling zone. When asymmetric solid-liquid heat and mass transfer occurs, the solidification point deviates from the center position, resulting in inconsistent microstructure and properties in the thickness direction of the plate. Although external energy fields such as ultrasonic and electromagnetic can have a certain intervention effect on the solidification process, they cannot fundamentally change the phenomenon of solidification point deviation.

[0006]In addition, current casting-rolling rolls mostly use roll sleeves made of a single metal material such as steel or copper. The biggest difference between steel and copper roll sleeves lies in their heat transfer capabilities. The specific heat capacities of the steel and the copper are close, but there is a significant difference in thermal conductivity. For example, a thermal conductivity of steel is 22 W/(m·K), while that of copper is 388 W/(m. K). Although the use of steel roll sleeves has advantages in terms of economic benefits, the poor heat transfer capability of the steel greatly limits the improvement of casting-rolling speed and the expansion of castable metal alloy grades. The use of the copper roll sleeves can achieve good heat transfer and thereby increase the casting-rolling speed. However, the connection between the copper roll sleeves and the steel roll cores is extremely difficult, and there are also problems such as difficult maintenance. Therefore, although casting-rolling technology has a good application prospect, there are still many urgent problems to be solved, including increasing the casting-rolling speed of monometallic metals, expanding the range of castable grades, achieving good heat transfer and low cost for the roll sleeves, improving the uniformity of alloy element distribution in the width direction of the plate, and avoiding deviation of the solidification point from the center position during asymmetric heat and mass transfer in solid-liquid casting-rolling composite processes.

SUMMARY

[0007]In order to address the deficiencies of the existing technologies mentioned above, the present disclosure provides a casting-rolling method based on a multi-layer heterogeneous composite roll sleeve and an apparatus thereof. By sequentially arranging a plurality of metal components along a circumferential direction of the composite roll sleeve, and adjusting combination modes between the metal components according to the structural and process parameters of monometallic metals and layered metal composite materials, the heat transfer thermal resistance path is analyzed. Based on a solidification temperature range of the target metal and the solidification point offset in the solid-liquid heat transfer process of layered metal composite materials, a layer thickness of the metal components in both the radial and axial directions of the composite roll sleeve is determined. This can ensure that the composite roll sleeve has good heat transfer capability while improving the uniformity of strip microstructure and alloy element distribution, thereby enhancing the forming quality of the strip.

[0008]To achieve the aforementioned objectives, the present disclosure adopts the following technical solutions:

[0013]Preferably, in step S3, when the target metal is a monometallic metal, liquid monometallic metal flows from the pouring system into the casting-rolling zone enclosed by the plurality of composite roll sleeves, and under solidification and rolling deformation actions of the composite roll sleeve, the solidification point is at the target solidification point position, and the liquid monometallic metal is solidified and deformed to obtain a monometallic metal strip.

[0014]Preferably, in step S3, when the target metal is a layered metal composite material, a solid base metal is fed into a solid casting-rolling zone enclosed by the plurality of composite roll sleeves through an uncoiling device, liquid cladding metal enters the solid-liquid casting-rolling zone from the pouring system, and under asymmetric solidification and rolling deformation actions of the plurality of composite roll sleeves, the solidification point is at the target solidification point position, and the liquid cladding metal is solidified and deformed to achieve metallurgical bonding with the solid base metal to obtain a layered metal composite material.

[0015]Preferably, each of the metal components has a uniform or variable layer thickness in the radial direction of the composite roll sleeve.

[0016]Preferably, the M metal components are arranged in N layers in an alternating manner along a circumferential direction of the composite roll sleeve, and N is an integer between M and 3M.

[0017]Preferably, the target solidification point position is a center of a roll gap, and the asymmetric heat transfer solidification point offset is an offset of the asymmetric heat transfer solidification point position relative to the target solidification point position.

[0018]According to another aspect, the present disclosure further provides a high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve, including: a main drive system, a main frame, a position control system, a pouring system, a casting-rolling mill set, and an uncoiling device, wherein an output shaft of the main drive system is connected to a first end of a roll core of the casting-rolling mill set, the casting-rolling mill set is disposed at a first end of the main frame, the position control system is disposed at a second end of the main frame and connected to the casting-rolling mill set, the uncoiling device is disposed at a third end of the main frame, and the pouring system is disposed at an end of the uncoiling device;

[0019]the casting-rolling mill set includes: a roll core, a first bearing seat, a composite roll sleeve, a second bearing seat, and a rotary joint, wherein the roll core extends axially through the first bearing seat, the composite roll sleeve, and the second bearing seat in sequence, the rotary joint is disposed at a second end of the roll core, the composite roll sleeve is connected to the roll core and rotates synchronously with the roll core, the roll core and the composite roll sleeve form an enclosed space, and the enclosed space is provided with circulating cooling water;

[0020]M metal components of the composite roll sleeve are arranged in N layers in an alternating manner along a circumferential direction of the composite roll sleeve, and a spatial metallurgical bonding composite interface is present between adjacent metal components.

[0021]Preferably, a shape of the composite interface is one or more of sine, cosine, spline, rectangular, triangular, or arc.

[0022]Preferably, a high-temperature-resistant ceramic coating is provided on an outermost side of the composite roll sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a structural schematic view of a high-speed casting-rolling apparatus based on a multi-layer heterogeneous composite roll sleeve of the present disclosure;

[0029]FIG. 2 is a structural schematic view of a casting-rolling mill set of the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure;

[0030]FIG. 3 is an axial sectional view of a composite roll sleeve with an axial spatial composite interface in the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure;

[0031]FIG. 4 is a radial sectional view of a composite roll sleeve with a radial spatial composite interface in the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure;

[0032]FIG. 5 is a sectional view showing variation of metal component layer in the compsite roll sleeve of the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure along the axial direction;

[0033]FIG. 6 is a schematic view of traditional monometallic metal casting-rolling heat transfer;

[0034]FIG. 7 is a schematic view of the monometallic metal casting-rolling heat transfer of the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure;

[0035]FIG. 8 is a schematic view of traditional solid-liquid casting-rolling composite heat transfer;

[0036]FIG. 9 is a schematic view of solid-liquid casting-rolling composite heat transfer of the high-speed casting-rolling apparatus based on the multi-layer heterogeneous composite roll sleeve of the present disclosure.

DETAILED DESCRIPTION

[0039]To elaborate the technical content, objectives, and effects of the present disclosure, a detailed description will be provided in conjunction with the accompanying figures of the present disclosure.

[0040]A high-speed casting-rolling apparatus based on a multi-layer heterogeneous composite roll sleeve of the present disclosure, as shown in FIG. 1, includes a main drive system 1, a main frame 2, a position control system 3, a pouring system 4, a casting-rolling mill set 5, and an uncoiling device 6. An output shaft of the main drive system 1 is connected to a first end of the roll core 501 of the casting-rolling mill set 5 via a coupling part. The main drive system 1 drives rotation of the roll core 501. The casting-rolling mill set 5 is disposed at a first end of the main frame 2. The position control system 3 is disposed at a second end of the main frame 2 and is connected to the casting-rolling mill set 5. The position control system 3 is used to adjust a roll gap between the two casting-rolling mill sets 5, enabling the production of strips at different dimensions. The uncoiling device 6 is disposed at a third end of the main frame 2 and is used to uniformly unwind and feed a coiled solid base metal into the casting-rolling mill set 5. The main frame 2 is configured to bear the entire rolling force. The pouring system 4 is disposed at an end of the uncoiling device 6 and is used for pouring liquid metal.

[0041]Furthermore, the casting-rolling mill set 5 may be disposed at the first end of the main frame 2 in a horizontal, inclined, or vertical manner. The uncoiling device 6 may be configured in one or more sets to achieve unwinding of solid base metal strips of the same or different types.

[0042]As shown in FIG. 2, the casting-rolling mill set 5 mainly includes a roll core 501, a first bearing seat 502, a composite roll sleeve 503, a second bearing seat 504, and a rotary joint 505. The roll core 501 extends axially through the first bearing seat 502, the composite roll sleeve 503, and the second bearing seat 504 in sequence. The rotary joint 505 is disposed at the second end of the roll core 501. The composite roll sleeve 503 is connected to the roll core 501 and rotates synchronously with the roll core 501. The roll core 501 and the composite roll sleeve 503 form an enclosed space. Cooling water introduced through the rotary joint 505 flows into the enclosed space to provide cooling during the casting-rolling process.

[0043]The composite roll sleeve 503 includes M metal components, which are arranged in N layers along a circumferential direction to form a multi-layer heterogeneous composite roll sleeve, where M≤N≤3M, and both M and N are positive integers. The term “multi-layer heterogeneous” means that multiple different metal components are arranged in N layers. In specific embodiments, a common arrangement is two metal components alternately arranged in two layers. A macroscopic or microscopic spatial metallurgical bonding composite interface is formed between adjacent metal components. A shape of the composite interface may be one or more of sine, cosine, spline, rectangular, triangular, or arc. In other embodiments, it may also be smooth or corrugated. An outermost side of the composite roll sleeve 503 includes a high-temperature-resistant ceramic coating with thermal shock resistance, thermal conductivity, and wear resistance, which directly contacts the solid-liquid metal material during the casting-rolling process. A layer thickness of the M metal components may be uniform or variable along a radial direction, that is, the layer thickness at different positions along the radial direction may be the same or different. As shown in FIG. 5, the layer thickness determines the heat transfer capability of the composite roll sleeve 503. Establishing a composite roll sleeve 503 with different layer thicknesses along the radial direction can adjust the heat transfer capability of the composite roll sleeve 503 at different radial positions. This can achieve uniform cooling of the strip in a width direction, thereby improving the uniformity of microstructural properties and enhancing the forming quality of the strip.

[0044]In a preferred embodiment, M is 2, and the M metal components are respectively a first metal component 5031 and a second metal component 5032. The first metal component 5031 is a copper alloy, and the second metal component 5032 is a steel alloy. A layer thickness of the first metal component 5031 and the second metal component 5032 in the radial direction may be consistent or varied according to actual needs. An axial sectional view of the composite roll sleeve with an axial spatial composite interface is shown in FIG. 3, and a radial sectional view of the composite roll sleeve with a radial spatial composite interface is shown in FIG. 4.

[0045]The schematic view of a traditional monometallic metal casting-rolling heat transfer is shown in FIG. 6. A casting-rolling zone mainly includes an inlet 100, a monometallic metal 101, a left casting-rolling roll 102, a right casting-rolling roll 103, a cooling water 106, and an outlet 105. Traditional monometallic metal casting-rolling is described as pouring monometallic metal between the two casting-rolling rolls to form a melt pool. Under a rapid solidification and rolling deformation action of the roll sleeve, the liquid monometallic metal solidifies and deforms to be a monometallic metal strip. Thermal resistance is an important factor affecting the cooling and solidification speed of the monometallic metals. The thermal resistance in the traditional monometallic metal casting-rolling heat transfer mainly includes thermal resistance between circulating cooling water inside the casting-rolling roll and the roll sleeve, thermal resistance within the roll sleeve during heat transfer, thermal resistance between the roll sleeve and the solidifying shell, and thermal resistance between the solidifying shell and the liquid metal in the heat transferring process.

[0046]The schematic view of monometallic metal casting-rolling heat transfer of a high-speed casting-rolling apparatus based on a multi-layer heterogeneous composite roll sleeve is shown in FIG. 7. The casting-rolling zone mainly includes an inlet 100, a monometallic metal 101, a left copper roll sleeve 111, a left steel roll sleeve 112, a right copper roll sleeve 113, a right steel roll sleeve 114, a cooling water 106, and an outlet 105. Unlike the traditional monometallic metal casting-rolling, the monometallic metal casting-rolling using a multi-layer heterogeneous composite roll sleeve employs a composite roll sleeve 503 based on the original process of the traditional monometallic metal casting-rolling. The thermal resistance in the monometallic metal casting-rolling heat transfer of the high-speed casting-rolling device based on the multi-layer heterogeneous composite roll sleeve includes thermal resistance between the circulating cooling water inside the casting-rolling roll and the roll sleeve, thermal resistance between the roll sleeve and the solidifying shell, and thermal resistance between the solidifying shell and the liquid metal. The thermal resistance during heat transfer within the composite roll sleeve is no longer singular, but become the thermal resistance during heat transfer within the first metal component 5031, the thermal resistance during heat transfer within the second metal component 5032, and the thermal resistance between the first metal component 5031 and the second metal component 5032. By designing the layer thickness of the first metal component 5031 and the second metal component 5032 in the two composite roll sleeves 503, the cooling and solidification speed of the monometallic metal can be changed.

[0047]The schematic view of traditional solid-liquid casting-rolling heat transfer is shown in FIG. 8. The solid-liquid casting-rolling zone mainly includes an inlet 100, a base metal 121, a cladding metal 122, a left casting-rolling roll 123, a right casting-rolling roll 124, a cooling water 106, and an outlet 105. In the traditional solid-liquid casting-rolling process, the solid base metal is fed into the solid-liquid casting-rolling zone enclosed by two roll sleeves through the uncoiling device 6 on one side, and the liquid cladding metal enters the solid-liquid casting-rolling zone from the pouring system on the other side. Under the asymmetric rapid solidification and rolling deformation action of the two roll sleeves, the liquid cladding metal solidifies and deforms to form a metallurgical bond with the solid base metal, resulting in a layered metal composite material. The heat transfer in the traditional solid-liquid casting-rolling composite processes is asymmetric. The thermal resistance on the left side of the solid-liquid casting-rolling composite mainly includes the thermal resistance between the circulating cooling water inside the casting-rolling roll and the roll sleeve, the thermal resistance during heat transfer within the roll sleeve metal, the thermal resistance between the roll sleeve and the solidifying shell, and the thermal resistance between the solidifying shell and the liquid cladding metal. The thermal resistance on the right side of the solid-liquid casting-rolling composite mainly includes the thermal resistance between the circulating cooling water inside the casting-rolling roll and the roll sleeve, the thermal resistance during heat transfer within the roll sleeve metal, the thermal resistance between the roll sleeve and the solid base metal, the thermal resistance between the solid base metal and the solidifying shell, and the thermal resistance between the solidifying shell and the liquid cladding metal.

[0048]The schematic view of a solid-liquid casting-rolling composite heat transfer of the high-speed casting-rolling apparatus based on a multi-layer heterogeneous composite roll sleeve is shown in FIG. 9. The solid-liquid casting-rolling zone mainly includes an inlet 100, a base metal 121, a cladding metal 122, a left copper roll sleeve 131, a left steel roll sleeve 132, a right copper roll sleeve 133, a right steel roll sleeve 134, a cooling water 106, and an outlet 105. Unlike the traditional solid-liquid casting-rolling composite process, the solid-liquid casting-rolling composite of the high-speed casting-rolling device based on the multi-layer heterogeneous composite roll sleeve employs a composite roll sleeve 503 based on the original process of traditional solid-liquid casting-rolling composite process. Based on the analysis of the heat transfer thermal resistance path, the thermal resistance in heat transfer during solid-liquid casting-rolling composite of the high-speed casting-rolling device of the multi-layer heterogeneous composite roll sleeve includes the thermal resistance between the circulating cooling water inside the casting-rolling roll and the roll sleeve, the thermal resistance during heat transfer within the roll sleeve metal, the thermal resistance between the roll sleeve and the solidifying shell, the thermal resistance between the solidifying shell and the liquid cladding metal, the thermal resistance between the roll sleeve and the solid base metal, and the thermal resistance between the solid base metal and the solidifying shell. The thermal resistance during heat transfer within the composite roll sleeve is no longer singular, but become the thermal resistance during heat transfer within the first metal component 5031, the thermal resistance during heat transfer within the second metal component 5032, and the thermal resistance between the first metal component 5031 and the second metal component 5032. By designing the layer thickness of the first metal component 5031 and the second metal component 5032 in the two composite roll sleeves 503, the cooling and solidification speed of the layered metal can be changed, thereby solving the problem of asymmetric heat transfer, achieving uniform cooling of the strip in the thickness direction, and improving the uniformity of microstructural properties.

[0054]Furthermore, in step S3, when the target metal is a monometallic metal, liquid monometallic metal flows from the pouring system 4 into the casting-rolling zone enclosed by the two composite roll sleeves 503. Under the rapid solidification and rolling deformation action of the two composite roll sleeves 503, the solidification point is at the target center position. After solidification and deformation, the liquid monometallic metal becomes a monometallic metal strip with the desired microstructure and properties.

[0055]Furthermore, in step S3, when the target metal is a layered metal composite material, the solid base metal is first fed into the solid-liquid casting-rolling zone enclosed by the two composite roll sleeves 503 through the uncoiling device 6. The liquid cladding metal enters the solid-liquid casting-rolling zone from the pouring system 4. Under the asymmetric rapid solidification and rolling deformation action of the two composite roll sleeves 503, the solidification point is at the target center position. After solidification and deformation, the liquid cladding metal forms a metallurgical bond with the solid base metal to produce a layered metal composite material with the desired microstructure and properties.

[0056]Furthermore, when two uncoiling devices 6 are used to unwind and feed two identical or different base metal strips into the solid-liquid casting-rolling zone enclosed by the two composite roll sleeves 503, the same uniform heat transfer in the width and thickness directions of the strip can be achieved by designing the combination mode and layer thickness of the metal components in the two composite roll sleeves 503. This can improve the forming speed and efficiency. The composite roll sleeve 503 mainly withstands the positive pressure and tangential frictional force. The locking effect of the macroscopic or microscopic spatial composite interface can significantly enhance the resistance to shearing and slippage.

[0057]The embodiments described above are merely illustrative of preferred embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. Any modifications and improvements made by a person skilled in the art to the technical solutions of the present disclosure, without departing from the spirit of the present disclosure, should fall within the scope of protection defined by the claims of the present disclosure.