Water cooling structure of casting roll for liquid continuous solidification forming of aluminum alloy sheet

Abstract

A water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin sheets is disclosed. The casting roll includes a roll core and a roll sleeve. The roll sleeve is fitted onto the roll core. An axial water inlet channel is provided at the center of the roll core end face. At least two water outlet channels parallel to the water inlet channel are provided beside the water inlet channel, with the inlet and outlet ends on the same side. The roll core end face corresponding to the other ends of the water inlet and outlet channels is closed. A ring of water-collecting grooves is provided circumferentially on the outer surface of the closed end of the roll core. These water-collecting grooves are connected to the water inlet channel through multiple connecting channels. Several sets of grooves are provided circumferentially on the roll core surface, each set consisting of two grooves. One end of each set of two grooves is connected, forming a U-shaped loop on the roll core surface. The inlet of the U-shaped loop communicates with the water-collecting grooves, and its outlet is connected to the water outlet channel through a connecting channel. The water-cooled structure of this invention can enhance the cooling intensity of the casting roll and significantly improve the axial cooling uniformity of the casting roll, thus meeting the requirement of high-speed aluminum alloy thin sheet preparation.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy slab preparation, and specifically relates to a water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates. Background Technology

[0002] With the development of modern technology and the national economy, the demand for aluminum alloy sheets, especially thin aluminum alloy sheets, is increasing. The main applications of thin aluminum alloy sheets include: aircraft and ship skins, automotive body panels (inner and outer panels), architectural decorative panels, and various foil blanks. Currently, the most promising short-process, low-cost method for producing thin aluminum alloy sheets is the casting-rolling-cold rolling method. This technology involves directly injecting liquid metal between two relatively rotating casting rolls, where it is solidified, cooled, and deformed during rolling to complete the forming process. The desired thin sheet or foil product is then produced through cold rolling. However, when using the casting-rolling method to produce high-alloy thin sheet products, defects such as center segregation, surface segregation, and rolling cracks in the slab can prevent production.

[0003] To further improve the adaptability of cast-rolled products, it is hoped that faster casting speeds can refine the microstructure of the cast-rolled plates, reduce segregation, thereby lowering the risk of rolling cracks and improving production efficiency. Typically, the conventional casting speed for aluminum alloy thin plates is about 1–2 m / min. During the casting process, due to fluctuations in the solidification front of the aluminum alloy melt, faster casting speeds can lead to aluminum leakage. However, the production of high-alloy slabs requires speeds several times, or even ten times, greater.

[0004] The fluctuations at the solidification front of aluminum alloy melt are closely related to the cooling of the casting roll. Higher casting speeds require further improvement in the cooling capacity of the casting roll, especially the axial uniformity of the entire casting roll surface. The existing internal water tank structure of aluminum alloy casting and rolling rolls is a circumferentially distributed groove with no cooling water between adjacent grooves, resulting in a large difference in axial cooling on the outside of the casting roll.

[0005] US Patent 6527042B1 proposes an improved structure to enhance the cooling uniformity of casting rolls: Based on the existing circumferential grooves, the design of the inlet and outlet water pipes is optimized. Three circumferential grooves are grouped together, and each group has its own inlet and outlet water passages. The inlet and outlet holes of adjacent groups of grooves are located at the same angular point on the roll's circumference, achieving a regular alternation of cooling water inflow and outflow. The different cooling capacities of adjacent cooling waters compensate for each other, improving the cooling uniformity of the entire roll surface. However, because the structure of US Patent 6527042B1 uses circumferential grooves, the inlet and outlet points are located within the working area of ​​the casting roll, which still leads to abrupt changes in axial cooling, making it difficult to meet the higher requirements for roll cooling uniformity in the preparation of high-alloy steel plates.

[0006] Chinese patent CN201510641053 discloses a method and apparatus for controlling the cooling intensity of casting rolls in twin-roll thin strip continuous casting. Each casting roll has one or more water inlets and one or more corresponding water outlets, thereby forming one or more individual cooling water channels inside the casting roll. A flow regulating valve is provided at the outlet of each cooling water channel. The cooling controller adjusts the flow rate q of the cooling water at the outlet based on the cooling water temperature t0 at the inlet of each cooling water channel. n Temperature t n Pressure p n Calculate the heat Q carried away by the cooling water in each cooling water channel within a single casting roll per unit time. n The amount of heat Q carried away by the cooling water in each cooling water channel of each casting roll per unit time. n Same; will be based on total heat ∑Q n Adjust the water flow rate q in the cooling water channel according to the deviation from the target value Q of heat carried away by the cooling water in the single casting roll cooling water channel per unit time. n Ultimately, the amount of heat removed by the cooling water in each casting roll per unit time is the same as the target heat value Q.

[0007] The Chinese patent CN201510641053 adopts a double-ended water inlet and outlet structure, with water entering from one end and exiting from the other. Each end has an inlet and outlet channel, and a separate control unit is used for flow and pressure control. The structure is complex and the control requirements are high. The cooling water flow is opposite in multiple cooling channels, but the cooling water in a single channel enters from one end of the roll sleeve and flows out from the other end. The cooling water flow is only the length of one roll sleeve. Improving the cooling efficiency can only be achieved by increasing the cooling water flow rate, and it is difficult to further improve the cooling intensity of the roll. Summary of the Invention

[0008] The purpose of this invention is to provide a water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy sheets, which can enhance the cooling intensity of the casting rolls and significantly improve the axial cooling uniformity of the casting rolls, thus meeting the requirement of fast aluminum alloy sheet preparation speed.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A water-cooled structure for a casting roll used in the continuous solidification and forming of aluminum alloy thin sheets, the casting roll comprising a roll core and a roll sleeve; the roll sleeve is fitted onto the roll core; wherein...

[0011] A water inlet channel is provided along the axial direction at the center of the roller core end face. At least two water outlet channels parallel to the water inlet channel are provided on the side of the water inlet channel, and the water inlet end and the water outlet end are on the same side. The roller core end face at the other end of the water inlet channel and the water outlet channel is closed. A water collection groove is provided around the outer surface of the closed end of the roller core along the circumference. The water collection groove is connected to the water inlet channel through multiple connecting holes.

[0012] The roller core surface is provided with several sets of grooves along the circumference, with two grooves in each set. One end of the two grooves is connected to form a U-shaped loop on the roller core surface. The inlet of the U-shaped loop is connected to the water collection groove, and its outlet is connected to the water outlet channel through a connecting channel.

[0013] Preferably, the roller core surface is provided with several sets of grooves along the circumference, with two grooves in each set. One end of the two grooves is connected, and the other end of one groove is blocked from the water collection groove. This end is provided with a connecting channel to the water outlet channel; the other end of the other groove is connected to the water collection groove.

[0014] Preferably, the bottom surface of the groove on the roller core surface is provided with a plurality of protrusions at intervals along the length direction, and the ratio of the height of the protrusion to the depth of the groove is 1:3 to 1:5.

[0015] Preferably, the bottom width of the boss is the same as the width of the groove, and the bottom length of the boss is 3 to 6 mm.

[0016] Preferably, the ratio of the distance between the two bosses to the width of the groove is 3:1 to 5:1.

[0017] Preferably, the protrusion has a triangular cross-section.

[0018] Compared with the prior art, the advantages of the present invention are as follows:

[0019] (1) This invention utilizes a unique design with multiple sets of grooves as the main cooling chambers of the casting roll. The cooling water flows in opposite directions in adjacent grooves, and the cooling water flow in a single groove is the length of two roll sleeves. The groove structure avoids the insufficient local cooling of the outer surface of the roll sleeve in the lateral direction caused by using circumferential grooves; and each set of grooves forms a U-shaped loop on the outer circumference of the roll core. The cooling water enters from one end and flows back at the other end. The cooling water flows in opposite directions in the two lateral branches of this loop. As the flow distance of the cooling water in the cooling chamber increases, its flow velocity decreases slightly and its water temperature increases slightly, and its cooling capacity gradually weakens. Therefore, the advantage of this design is that by adjusting the flow direction of the cooling water, the strong cooling part compensates for the weak cooling part, thereby ensuring the uniformity of lateral cooling of the roll sleeve.

[0020] Meanwhile, the U-shaped loop design of the groove in this invention allows the cooling water flow within a single groove to be the length of two roller sleeves, doubling the distance for convective heat exchange with the roller core and roller sleeve. Furthermore, the change of direction of the cooling water during flow can enhance the degree of turbulence, improve the heat exchange efficiency of the cooling water, and enhance the cooling intensity of the casting roller.

[0021] Although the structure of Chinese patent CN201510641053 adopts a transverse cooling channel and the cooling water flow is opposite in multiple cooling channels, the cooling water in a single channel enters at one end of the roller sleeve and flows out at the other end. The cooling water flow is only the length of one roller sleeve, so its heat exchange and cooling efficiency is relatively poor.

[0022] (2) In this invention, the water inlet and outlet are both on the same side, and only one cylindrical water inlet channel is used, which avoids the inconsistency in water pressure and flow rate caused by multiple water inlet channels, thus avoiding uneven cooling. Since the water inlet and outlet are both on the same side, and there is no need for additional control components due to multiple water inlet channels, the device structure is simple and compact.

[0023] (3) In this invention, grooves are used as the main cooling channels for the casting roll, and several protrusions are evenly distributed on the bottom surface of the grooves. Cooling water flows in the grooves. When it flows past the protrusions, the cross-sectional area decreases and its flow velocity increases. After passing the protrusions, the flow velocity decreases. Several protrusions are regularly distributed in a single set of transverse grooves. The velocity of the cooling water changes continuously throughout the entire flow process, which disturbs the laminar flow state of the cooling water at the groove boundary and increases the turbulence of the cooling water in the entire groove, thereby improving the heat exchange efficiency of the cooling water and enhancing the cooling intensity of the casting roll. Attached Figure Description

[0024] Figure 1 This is a perspective view of an embodiment of the present invention;

[0025] Figure 2 This is an exploded perspective view of an embodiment of the present invention;

[0026] Figure 3 This is a top view of the roller core in an embodiment of the present invention;

[0027] Figure 4 for Figure 3 AA section view;

[0028] Figure 5 for Figure 3 BB section view;

[0029] Figure 6 for Figure 3 CC section view;

[0030] Figure 7 This invention provides a three-dimensional representation of the cooling water distribution in the water-cooled structure application of the casting roll in this embodiment. Figure 1 ;

[0031] Figure 8 This invention provides a three-dimensional representation of the cooling water distribution in the water-cooled structure application of the casting roll in this embodiment. Figure 2 ;

[0032] Figure 9In the application of the water-cooled structure for casting rolls in this embodiment of the invention, multiple sets of cooling water are distributed ( Figure 7 , 8 (Chinese) tiling diagram;

[0033] Figure 10 for Figure 8 The front view;

[0034] Figure 11 for Figure 9 The front view;

[0035] Figure 12 Temperature distribution cloud maps of the outer surface of rolls with different structures;

[0036] Figure 13 Temperature distribution cloud maps of the contact surfaces between rolls with different structures and molten aluminum;

[0037] Figure 14 This is a temperature distribution diagram of the contact line between rolls with different structures and molten aluminum. Detailed Implementation

[0038] See Figures 1 to 11 The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin sheets according to the present invention includes a roll core 1 and a roll sleeve 2; the roll sleeve 2 is assembled onto the roll core 1; wherein,

[0039] A water inlet channel 101 is provided axially at the center of the end face of the roller core 1. At least two water outlet channels 102 parallel to the water inlet channel 101 are provided on the side of the water inlet channel 101, and the water inlet end and the water outlet end are on the same side. The end face of the roller core 1 at the other end of the water inlet channel 101 and the water outlet channel 102 is closed. A water collecting groove 103 is provided circumferentially on the outer surface of the closed end of the roller core 1. The water collecting groove 103 is connected to the water inlet channel 101 through multiple connecting holes 104.

[0040] The roller core 1 has several sets of grooves 105 arranged circumferentially on its surface. Each set has two grooves, and one end of each groove is connected to form a U-shaped loop on the surface of the roller core 1. The inlet of the U-shaped loop is connected to the water collection groove 103, and its outlet is connected to the water outlet channel 102 through the connecting channel 106.

[0041] Preferably, the surface of the roller core 1 is provided with several sets of grooves along the circumferential direction, with two grooves in each set. One end of the two grooves is connected, and the other end of one groove is blocked from the water collection groove. The other end of the groove is provided with a connecting channel to the water outlet channel; the other end of the other groove is connected to the water collection groove.

[0042] Preferably, the bottom surface of the groove 105 on the surface of the roller core 1 is provided with a plurality of protrusions 107 at intervals along the length direction, and the ratio of the height of the protrusion to the depth of the groove is 1:3 to 1:5.

[0043] Preferably, the bottom width of the boss is the same as the width of the groove, and the bottom length of the boss is 3-6 mm.

[0044] Preferably, the ratio of the distance between the two protrusions to the width of the groove is 3:1 to 5:1.

[0045] Figures 7-11 The diagram shown is a cooling water distribution diagram in the application of the water-cooled structure of the casting roll of the present invention. For the sake of explaining the cooling water distribution, the main body of the roll core 1 and the roll sleeve 2 has been removed from the diagram.

[0046] After the main inlet column a is filled, it forms a branch inlet column b, which in turn forms an inlet ring c. The inlet ring c provides sufficient cooling water for multiple groups of cooling water flow d. Each group of cooling water flow d is divided into cooling water sub-flows d1 and d2. Each group of cooling water flow d merges into the outlet column e through its corresponding branch outlet column f.

[0047] Because the structure of this invention has only one water inlet channel, it avoids the use of multiple water inlet channels, thereby avoiding slight differences in water pressure and flow rate between different water inlet channels. At the same time, a circumferential water collection groove 103 is cleverly designed. Cooling water enters the water collection groove 103 to form a water inlet ring c. The water inlet ring c maintains a certain pressure, which can provide several sets of cooling water flows d with uniform pressure and flow rate to several sets of grooves 105. Since the cooling water in each set of grooves 105 travels the same path, it ensures that the cooling water pressure and flow rate in the groove are uniform.

[0048] This invention utilizes a unique design with multiple sets of grooves 105 as the main cooling chambers for the roller core and sleeve, avoiding the insufficient axial cooling of the outer surface of the sleeve caused by using circumferential water collection grooves. Furthermore, each set of grooves 105 forms a U-shaped loop on the outer circumference of the roller core. Cooling water enters from one end and flows axially, then turns back axially at the other end, with the two axial branches of this loop flowing in opposite directions. The molten aluminum solidifies under the cooling of the casting roller, causing the roller temperature to rise. The cooling water carries the heat from the casting roller. As the flow distance in the cooling chamber increases, the flow rate of the cooling water decreases slightly, and the water temperature gradually increases, thus gradually weakening its cooling capacity. Therefore, the advantage of this design is that by adjusting the flow direction of the cooling water, the stronger cooling areas compensate for the weaker cooling areas, thereby ensuring the uniformity of lateral cooling of the sleeve.

[0049] The cooling water flow d within a single groove 105 flows back and forth between the two ends of the roller sleeve, a distance of two roller sleeve lengths. This doubles the distance for convective heat exchange with the roller core and roller sleeve. Furthermore, the cooling water changes direction during its flow, which enhances the degree of turbulence.

[0050] Since several protrusions 107 are evenly distributed on the bottom surface of each groove 105, the cooling water flow d flows in the groove 105. When it flows through the protrusion 107, the cross-sectional area decreases and its flow velocity increases. After passing the protrusion 107, the flow velocity decreases. Since several protrusions 107 are regularly distributed in a single set of grooves 105, the velocity of the cooling water changes continuously throughout the entire flow process, which disturbs the laminar flow state of the cooling water at the groove boundary and increases the degree of turbulence of the cooling water in the entire groove, thereby improving the heat exchange efficiency of the cooling water and improving the cooling intensity of the casting roll.

[0051] The cooling uniformity of conventional casting rolls and the structure of this invention was compared through numerical simulation calculations.

[0052] 1. Modeling parameters:

[0053] The outer diameter of the casting and rolling roll sleeve is 200mm, the thickness is 15mm, and the roll width is 500mm; the thickness of the prepared slab is 8mm; the contact angle of the slab is 19.5° (arc length 75mm); the material of the roll sleeve and the roll core is 32CrMo1V alloy steel.

[0054] The standard structure uses a circumferential groove with a depth of 4mm, a width of 8mm, and a center distance of 16mm.

[0055] The structure of this invention adopts an axial transverse groove with a depth of 4mm, a width of 8mm, and a center distance of 16mm. The bottom width of the transverse groove protrusion is 4mm, the height is 1mm, and the center distance is 31mm.

[0056] 2. Cooling process parameters:

[0057] The rolling mill linear speed is 1 m / min, the aluminum liquid temperature is 700℃, the aluminum plate temperature leaving the rolling mill is 380℃, the water flow rate is 75.4 L / min, and the water temperature entering the mill is 20℃.

[0058] Figures 12-14 These are the results of numerical simulation.

[0059] Figure 12 The temperature distribution cloud map of the outer surface of the roll with different structures shows that, compared with the conventional structure, the highest and lowest temperatures of the outer surface of the roll decreased after adopting the structure of the present invention, from 527.6℃ and 166℃ to 437.5℃ and 122.8℃, respectively, indicating that the structure of the present invention can increase the cooling effect.

[0060] Figure 13 The figures show temperature distribution cloud maps of the contact surfaces between rolls with different structures and molten aluminum. As can be seen from the figures, the transverse temperature distribution of the casting roll structure of the present invention is more uniform.

[0061] Figure 14The temperature distribution diagrams of the contact lines between the rolls and the molten aluminum with different structures show that the transverse temperature difference of the casting rolls using the structure of this invention is 1.2℃, while the temperature difference of the conventional structure is 13.0℃.

[0062] Simulation results show that the cooling capacity of the casting roll is enhanced and the uniformity of cooling is greatly improved after adopting the structure of the present invention, which will help to increase the casting speed and produce high-quality aluminum alloy slabs.

Claims

1. A water-cooled structure for a casting roll used in the continuous solidification forming of aluminum alloy thin sheets, the casting roll comprising a roll core and a roll sleeve; the roll sleeve being fitted onto the roll core; characterized in that: A water inlet channel is provided along the axial direction at the center of the roller core end face. At least two water outlet channels parallel to the water inlet channel are provided on the side of the water inlet channel, and the water inlet end and the water outlet end are on the same side. The roller core end face at the other end of the water inlet channel and the water outlet channel is closed. A water collection groove is provided around the outer surface of the closed end of the roller core along the circumference. The water collection groove is connected to the water inlet channel through multiple connecting holes. The roller core surface is provided with several sets of grooves along the circumference, with two grooves in each set. One end of the two grooves is connected to form a U-shaped loop on the roller core surface. The inlet of the U-shaped loop is connected to the water collection groove, and its outlet is connected to the water outlet channel through a connecting channel.

2. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 1, characterized in that, The roller core surface is provided with several sets of grooves along the circumference, with two grooves in each set. One end of the two grooves is connected, and the other end of one groove is blocked from the water collection groove. This end is provided with a connecting channel to the water outlet channel; the other end of the other groove is connected to the water collection groove.

3. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 1, characterized in that, The bottom surface of the groove on the roller core surface is provided with several protrusions at intervals along the length direction, and the ratio of the height of the protrusion to the depth of the groove is 1:3 to 1:

5.

4. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 3, characterized in that, The bottom width of the boss is the same as the width of the groove, and the bottom length of the boss is 3-6 mm.

5. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 3 or 4, characterized in that, The ratio of the distance between the two bosses to the width of the groove is 5:1 to 3:

1.

6. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy sheets as described in claim 3, 4, or 5, characterized in that, The protrusion has a triangular cross-section.

7. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 1, characterized in that, The roller sleeve is interference-fitted onto the roller core.

8. The water-cooled structure for casting rolls used in the continuous liquid solidification forming of aluminum alloy thin plates as described in claim 1, characterized in that, The water inlet and outlet channels are circular.

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