A crystallization roller movement method and device for double-roll thin strip process

Abstract

This application document proposes a crystallization roller movement method and device for a twin-roll thin strip process, which belongs to the field of twin-roll casting technology. During the floating process of the roller gap, the movement trajectory of the moving roller is oblique to the reference plane. Compared with the traditional method and device, the present invention can more effectively promote the early collapse of the long-range shear thinning interface in the molten pool to reduce the peak pressure of the molten pool, prevent the leakage of the side sealing plate, damage to the side sealing plate, jamming, breaking, cracking and other various process stability problems caused by the excessive peak pressure of the molten pool, and can improve the uniformity of the thickness of the cast strip and reduce the fluctuation amplitude of the top tightening force of the crystallization roller.

Description

Technical Field

[0001] The invention belongs to the technical field of twin-roll casting and rolling, and in particular relates to a crystallization roll movement method and device for a twin-roll thin strip process. Background Art

[0002] The concept of twin-roll thin strip was proposed more than a century and a half ago, but the basic technical features have not changed. It has also achieved great success in the field of non-ferrous metals and is a standard method for preparing aluminum and its alloy thin strips. In the field of steel, major economies have conducted intensive research and development on the twin-roll thin strip process. Nucor in the United States took the lead in commercializing steel thin strips around 2000. Nucor attributes the commercialization of twin-roll thin strips to the enhancement of the overall industrial strength under the progress of the times, including four aspects: control (High speed computing and process control); materials (Advanced ceramics and materials); sensors (Sensing technology); mathematical models (Mathematical modeling of physical phenomena). Although Nucor has achieved commercial success, a doctoral student named Luiten, during his doctoral student period, interviewed relevant personnel engaged in twin-roll thin strip research internationally and finally believed that there has been no decisive and far-reaching progress in twin-roll thin strips since its birth. In his doctoral dissertation, Dr. Luiten elaborated on his interview process and conclusions in detail. At present, the world's four commercial twin-roll thin strip production lines (in the United States, Mexico, and China) are all built on the original foundation of Nucor. The reasons for Nucor's success have not been made public, but Nucor's process route has certain limitations in the composition of steel grades that can be produced. Compared with non-ferrous metals, the development of twin-roll thin strip technology in the steel field is slow. There are many reasons for failure reflected by various research institutions, and the root cause is that researchers cannot accurately grasp the molten pool transmission behavior, which is the cornerstone of process stability and cast strip quality control.

[0003] Due to the unique structure of the twin-roll casting machine, there was no experimental means in the world to directly study the transmission process in the molten pool before the inventors proposed the tracer method (invention patent application number: 2021101226378; invention name: a method for characterizing the transmission behavior in the molten pool during twin-roll casting) and the kiss angle measurement method (invention patent application number: 2021112909655; invention name: a method for measuring the kiss angle of twin-roll casting). The technical basis of the tracer method is the turbulent zoning phenomenon in the molten pool that the inventors first discovered. For the turbulent zoning phenomenon in the molten pool, please refer to the literature: "Physical and computational study of a novel submerged entry nozzle design for twin-rollcasting process" (Journal of Iron and Steel Research International, 2021, P1390-1399). The Kiss angle measurement method uses the difference in element concentration distribution during the solidification process to capture the development process of the billet shell when it passes through the two-phase region. The Kiss angle measurement method does not use the organizational characteristics of the molten pool ingot because the phase change process of the molten pool ingot obtained by the emergency stop method is complex, and the organizational characteristics obtained at the moment of emergency stop are still changing.

[0004] In the absence of experimental means, the researchers believe that the growth law of the solidified shell in the molten pool is similar to that of the adjacent Figure 1 As described in . Figure 1 This is common knowledge in the field, but has never been confirmed by actual experiments. Figure 1 References: "Progress in twin roll casting of magnesium alloys, A review" (Journal of Magnesium and Alloys, 2021, P362-391); "Simulation of microstructures insolidification of aluminum twin-roll casting" (Transactions of NonferrousMetals Society of China, 2012, P1452-1456).

[0005] According to the attached Figure 1 , people in the field proposed to use the roll gap floating method to enhance process stability and improve the quality of the cast strip.

[0006] Roll gap floating means that during the casting process, at least one of the two crystallization rollers is driven by a driving device to move, so that the relative position of the two oppositely rotating crystallization rollers changes. The minimum distance between the two crystallization rollers is called the roll gap, and the midpoint of the roll gap is called the Nip point. In three-dimensional space, the roll gap is a surface and the Nip point is a line. The roll gap opening refers to the minimum distance between the two crystallization rollers. When there is no roll gap floating, the plane where the roller axes of the two crystallization rollers are located is called the reference plane. The roll axis refers to the rotation axis of the crystallization roller when it rotates, and the rotation axis is an imaginary auxiliary line.

[0007] There are two traditional roller gap floating methods, as shown in the attached Figure 2 and attached Figure 3 Attached Figure 2 The zero angle motion method is shown (invention patent application number 2017800317704, invention name: Method for operating a twin-roll thin strip continuous casting machine to reduce vibration). Figure 3 The vertical motion method is shown (invention patent number: 2007101853779, invention name: vibrating twin-roller thin strip casting and rolling mill).

[0008] Attached Figure 2 and attached Figure 3 The key problems of the prior art shown are: poor process stability, very few steel materials that can be prepared, the two-phase zone of the steel grade cannot be too wide or too narrow, and even the steel grades that can be commercially prepared now still have common process stability problems such as tape jamming, tape breakage, side sealing plate leakage, and side sealing plate damage. The cast strip leaving the molten pool is prone to common defects such as "backbone", "snake eggs" and "egg-filled pancakes", and the thickness of the cast strip fluctuates greatly. The casting and rolling force also fluctuates greatly. The casting and rolling force is also called the crystallization roller top tightening force, sometimes also called casting force. Over the past century and a half, the key reason why the process stability problem and the cast strip quality problem have not been better improved is: there is a lack of strategies to study the actual molten pool transmission behavior. Figure 1 It cannot explain the scientific mechanisms behind the diverse process stability problems and cast strip quality issues that technicians actually encounter. Summary of the invention

[0009] The inventors obtained the following results based on the tracer method and the kiss angle measurement method: Figure 4 The results shown in (see Chinese patent document with application number 2021112909655) show that in a certain period of time, the "solidified shell" in the molten pool is actually like the attached Figure 4 Developed as shown in . Figure 1 and attached Figure 4 The difference is: Figure 1 In the figure, the two curves converge into a kiss point; Figure 4 In the figure, two straight lines converge into a kiss point. Figure 4 The experimental results show that the Figure 1This understanding is essentially wrong. Figure 4 The schematic diagram is as attached Figure 5 As shown, attached Figure 5 It is drawn based on the tracer technology and the kiss angle measurement technology. Figure 5 It is also the first time in the world that the transmission behavior characteristics within the molten pool in the presence of a long-range shear thinning interface have been clearly and completely described.

[0010] The inventor's subsequent research shows that Figure 4 The two straight lines observed in the figure are actually two long-range shear thinning planes. These two long-range shear thinning interfaces are quasi-periodic collapses. There are quasi-periodic material, momentum and energy transfer behaviors in the molten pool, such as the attached Figure 6 To Attachment Fig.10 shown.

[0011] Attached Figure 6 It is not a continuous and stable stage. Due to multiple factors, the two-phase zone at the bottom of the molten pool becomes wider, and a long-range shear thinning interface appears at the bottom of the molten pool. The long-range shear thinning interface converges into a kiss angle, forming an adhering Figure 7 Since the two long-range shear thinning interfaces that converge into the kiss point have different velocity directions, the kiss point does not actually exist. The kiss point is actually a highly disordered area with a very small range. However, it is difficult to give a specific value for how small it is. Based on many years of research experience, the inventor believes that it should be at the level of several microns to tens of microns.

[0012] Attached Figure 7 In the process, the long-range shear thinning interface hinders the transmission of the driving force of the crystallization roller, resulting in the material in the area sandwiched by the two long-range shear thinning interfaces being unable to obtain the driving force required to move out of the molten pool. Therefore, the Kiss corner material is not easy to be renewed. The difficulty in renewing the Kiss corner material will promote the further development of the long-range shear thinning interface, forming an attached Figure 8 The material at the kiss angle formed by the convergence of two long-range shear thinning interfaces (or long-range shear thinning planes) is not easy to renew.

[0013] Attached Figure 8 In the process, the long-range shear thinning interface continues to develop, the cold zone area in the molten pool expands, and the temperature of the cold zone continues to decrease. The depth of the molten pool is certain. When the cold zone range increases and the temperature decreases, the hot zone range shrinks accordingly and the temperature increases. The temperature difference between the cold zone and the hot zone further increases, and the molten pool transmission environment becomes extreme. The continuous development of the long-range shear thinning interface shows an inhibitory effect on the melt flow range. The shear thinning behavior of semi-solid metals is unstable. Due to the continuous decrease in the temperature at the bottom of the molten pool, the long-range shear thinning interface naturally collapses, forming an attached Fig. 9 .

[0014] Attached Fig. 9In the process, the long-range shear thinning interface collapses, the materials on both sides of the long-range shear thinning interface are welded together, the shear extrusion zone in the molten pool instantly becomes a rolling zone, and the shear process instantly becomes a rolling process, causing a sudden increase in the pressure in the molten pool, forming a pressure peak. The collapse of the long-range shear interface will lead to three possibilities: the crystallization roller stops rotating, such as the crystallization roller is stuck after the materials on both sides of the long-range shear thinning plane are welded; the strong rolling process, and the consequences that are sufficient to interrupt the process, such as the peak pressure acting on the side sealing plate, causing the side sealing plate to be pushed open, causing leakage at the side sealing plate, and the peak pressure will also cause the side sealing plate to be damaged and\or the attachments on the side sealing plate to fall off; the strong rolling process, but does not cause the consequences that are sufficient to interrupt the process, such as cracks and reduced uniformity of cast strip thickness. The pressure peak is higher near the end of the crystallization roller due to the lower temperature. The peak pressure in the molten pool will also greatly wear the crystallization roller and reduce the service life of key equipment.

[0015] Attached Fig.10 In the figure, the cold zone is the intense rolling zone, the material in the rolling zone moves out of the molten pool, the area of ​​the cold zone shrinks, the hot zone moves downward, the temperature of the flow zone decreases, and the temperature of the cold zone increases. Fig.10 Back to the attached Figure 6 Due to the high temperature in the hot zone, a "bright line" may appear across the casting strip. The existence of the "bright line" can prove that the periodicity of the transmission process is synchronous along the roller body direction.

[0016] Patent application documents and attachments of this invention Figure 2 and attached Figure 3 The difference between the conventional method shown is that the invention is based on a different starting point: the present invention is based on the attached Figure 4 To Attachment Fig.10 The understanding in Figure 4 To Attachment Fig.10 It was first obtained by the inventors in the world by using the tracer method and the kiss angle measurement method; Figure 2 and attached Figure 3 The conventional method shown is based on the attached Figure 1 Coming from, and attached Figure 1 The phenomenon shown is caused by misconceptions in the field.

[0017] Patent application documents and attachments of this invention Figure 2 and attached Figure 3 The difference between the conventional method shown in the figure is that the effect is different: in the patent application document of the present invention, the moving direction of the moving roller points to the adjacent Figure 4 and attached Figure 5 The long-range shear thinning interface shown in FIG. Figure 2 and attached Figure 3 In the process, the movement direction of the crystallization roller is not directed toward the long-range shear thinning interface in the molten pool.

[0018] In view of the shortcomings in the background technology, the present invention proposes a crystallization roller movement method and device for a double-roll thin strip process. The method and device adopt a completely different idea from the prior art. The semi-solid metal shear thinning theory and the double-roll thin strip experiments conducted by the inventors show that the method and device proposed in the present invention can greatly improve the various process stability problems caused by the excessively high pressure peak in the molten pool in the prior art, and can improve the quality of the cast strip.

[0019] The present invention provides a crystallization roller motion method for a double-roll thin strip process, taking any plane φ perpendicular to the roller axis of the first crystallization roller, the projection of the first crystallization roller on the plane φ is a circle with point O1 as the center, the projection of the second crystallization roller on the plane φ is a circle with point O2 as the center, the first crystallization roller and / or the second crystallization roller are moving rollers, and the position relationship between the motion trajectory of the center of the projection of the moving roller on the plane φ and the straight line where the line segment O1O2 is located is oblique. The angle formed by the oblique intersection is called the oblique intersection angle.

[0020] The motion trajectory of the center of the projection of the moving crystallization roller on the plane φ may be a straight line or an arc. If the motion trajectory of the center of the projection of the moving roller on the plane φ is an arc segment, then the tangent at any point on the arc segment (excluding the end point) is taken, and the oblique angle at this time is the oblique angle between the tangent and the straight line where the line segment O1O2 is located.

[0021] Whether the motion trajectory of the crystallization roller is a straight line or an arc should be determined by the structure of the equipment. If the equipment is designed to make the motion trajectory of the crystallization roller a straight line, then even if the motion trajectory is deformed due to the load during the casting and rolling process, the deformed motion trajectory should still be identified as a straight line; if the equipment is designed to make the motion trajectory of the crystallization roller an arc, then even if the motion trajectory is deformed due to the load during the casting and rolling process, the deformed motion trajectory should still be identified as an arc.

[0022] Since the cross section of the actual crystallization roller perpendicular to the roller axis of the crystallization roller cannot be a perfect circle, there are non-circular roller shapes that are manufactured and / or specially designed, and the load under the working state will also cause the crystallization roller to deform, therefore, the projection of the crystallization roller on the plane φ should be considered as an approximate circle, and the center of the circle should be considered as the center of mass. In particular, for example, if the projection of the crystallization roller on the plane φ is a rectangle (or any polygon), then the rectangle should be considered as an approximate circle, and the center of mass of the rectangle (or any polygon) should be considered as the center of the approximate circle.

[0023] The motion trajectory of the center of the projection of the moving crystallization roller on the plane φ may be a straight line or an arc. The arc refers to a continuous line with a certain curvature. The arc includes a circular arc, an elliptical arc, and a parabola. The curve can be decomposed into several arcs.

[0024] In the present application, the centers O1 and O2 are the starting centers, and the starting centers are defined as the points at which the crystallization rollers start to move. When the moving crystallization roller starts to move, the center of the circle generated by its projection on the plane φ is the starting center, and the definition of the starting center is for the convenience of explaining the skew angle. It is fully understood by ordinary technicians in the field that the centers O1 and O2 are the centers of the projections of the two crystallization rollers on the plane φ when roller gap floating does not occur. When roller gap floating does not occur, in three-dimensional space, the plane formed by the roller axes of the two crystallization rollers is called the reference plane. When roller gap floating does not occur, the projection of the first crystallization roller on the plane φ is a circle with point O1 as the center, and the projection of the second crystallization roller on the plane φ is a circle with point O2 as the center.

[0025] Furthermore, a crystallization roller movement method for a double-roll thin strip process is provided, wherein the movement trajectory of the center of the projection of the moving roller on the plane φ is a straight line segment.

[0026] Furthermore, in a crystallization roller movement method for a double-roll thin strip process, in the plane φ, the movement trajectory of the center of the projection of the moving roller is an arc segment.

[0027] Furthermore, a crystallization roller movement method for a double-roll thin strip process is provided, wherein the oblique angle is not greater than 60 degrees and the oblique angle is not less than 3 degrees.

[0028] Furthermore, a crystallization roller movement method for a double-roll thin strip process is provided, wherein the skew angle is in the range of 6 to 15 degrees.

[0029] Furthermore, a crystallization roller movement method for a twin-roll thin strip process is provided, wherein the skew angle is variable or constant, and the movement of the moving roller is periodic or non-periodic.

[0030] Further, a crystallization roller motion method for a double-roll thin strip process, the motion of the motion roller can be periodic or non-periodic. The motion elements of the motion roller include motion speed, motion amplitude, motion frequency, and angle with the straight line where O1O2 is located, and the change of any one of the motion elements of the motion roller can be periodic or non-periodic.

[0031] Furthermore, a crystallization roller movement method for a double-roll thin strip process is provided, wherein the first crystallization roller and the second crystallization roller are both the moving rollers, the first crystallization roller moves at a constant oblique angle δ, and the second crystallization roller moves at a constant oblique angle η, wherein δ is the same as or different from η.

[0032] A device for a crystallization roller movement method for a double-roll thin strip process, comprising the first crystallization roller, the second crystallization roller, a first crystallization roller bearing seat, a second crystallization roller bearing seat, and a frame, wherein the geometric shape of the frame is used to constrain the movement of the crystallization roller, and the geometric shape of the frame refers to the geometric shape of the contact area between the bearing seat and the frame when the bearing seat of the crystallization roller and the frame move relative to each other, the first crystallization roller is connected to the frame via the first crystallization roller bearing seat, and the second crystallization roller is connected to the frame via the second crystallization roller bearing seat; the first crystallization roller or / and the second crystallization roller are the moving rollers, and the moving rollers are connected to a driving mechanism, and the driving mechanism drives the moving rollers and their bearing seats to move under the constraint of the geometric shape; wherein the movement of the moving rollers and their bearing seats driven by the driving mechanism refers to the movement of the moving rollers relative to the frame, excluding the self-rotational movement of the moving rollers themselves;

[0033] Take the plane ψ formed by the roller axis of the first crystallization roller and the roller axis of the second crystallization roller, then the constraint generated by the geometric shape of the frame should make the plane where the motion trajectory of the roller axis of the first crystallization roller and / or the roller axis of the second crystallization roller is located obliquely to the plane ψ. The plane ψ refers to the plane where the roller axis of the first crystallization roller and the roller axis of the second crystallization roller are located when the roller gap does not float. Since the cross section of the actual crystallization roller perpendicular to the roller axis of the crystallization roller cannot be a perfect circle, there are non-circular roller shapes that are manufactured and / or specially designed, and the load under the working state will also cause the crystallization roller to deform, therefore, the cross section perpendicular to the roller axis of the crystallization roller should be considered as an approximate circle, the center of the circle should be considered as the center of mass, and the roller axes of the two crystallization rollers should be considered as two parallel straight lines in a certain plane. The plane where the motion trajectory of the roller axis of the first crystallization roller and / or the roller axis of the second crystallization roller is located is obliquely to the plane ψ. When the motion trajectory is a curved surface, the plane where the motion trajectory is located is a series of tangent planes.

[0034] Further, in a device, the oblique angle is in the range of 1.5 to 15 degrees or in the range of 30 to 45 degrees.

[0035] Furthermore, in a device, the first crystallization roller moves under the constraint of a frame, the second crystallization roller is fixed, and the surface swept by the roller shaft of the first crystallization roller is a plane or a curved surface. The roller shaft of the first crystallization roller is regarded as an ideal straight line, and the identification of the plane or curved surface should be inferred from the design of the frame. If the constraint of the frame is curved, the surface swept by the roller shaft is a curved surface. The combination of a partial plane and a partial curved surface should be identified as a curved surface. The inclined frame and / or the curved frame are provided with a track for reducing the movement resistance of the first crystallization roller bearing seat and / or the second crystallization roller bearing seat.

[0036] The method involved in this application document can be used not only for steel thin strips, but also includes but is not limited to the use of a twin-roll casting method to prepare composite thin strips, aluminum alloy thin strips, copper alloy thin strips, and high entropy alloy thin strips.

[0037] The beneficial effects of the present invention are as follows: the present invention uses a crystallization roller movement method and device for a double-roll thin strip process to more efficiently promote the early collapse of the long-range shear thinning interface, prevent the excessive development of the long-range shear thinning interface from causing some materials in the molten pool to be unable to be renewed, avoid the peak pressure in the molten pool that is sufficient to cause process instability due to the collapse of the long-range shear thinning interface after excessive development, inhibit side sealing plate leakage, side sealing plate damage, tape jamming, tape breakage, and cracks caused by excessive peak pressure in the molten pool, reduce the fluctuation amplitude of the top tightening force of the crystallization roller during the floating process of the roller gap, improve the uniformity of the thickness of the cast strip, and achieve the effect of stabilizing the process and improving the quality of the cast strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the traditional understanding of the development process of the solidifying shell in the molten pool.

[0039] Figure 2 The figure shows a schematic diagram of a zero-angle motion method in which the two rollers are always located in a reference plane.

[0040] Figure 3 Shown is a schematic diagram of the vertical movement method.

[0041] Figure 4 This is the experimental result of the presence of a long-range shear thinning interface when the tracer method and the kiss measurement method are implemented together.

[0042] Figure 5 Schematic diagram of the existence of a long-range shear thinning interface for tracer experiments and kiss angle measurement experimental results.

[0043] Figure 6 It is a schematic diagram showing that there is no significant rolling stage or no rolling stage during the periodic transport of the molten pool.

[0044] Figure 7 Shown is a schematic diagram of the formation of a long-range shear thinning interface during the periodic transport of the molten pool.

[0045] Figure 8 Shown is a schematic diagram of the development of a long-range shear-thinning interface during periodic transport of the melt pool.

[0046] Fig. 9 Shown is a schematic diagram of the collapse of the long-range shear thinning interface during the periodic transport of the melt pool.

[0047] Fig.10 Shown is a schematic diagram of the intense rolling process during periodic transport of the molten pool.

[0048] Fig.11 The first roller axis along the straight line segment O1O in Example 1 of the present invention is shown. 1-1 Schematic diagram of the movement.

[0049] Fig.12 The first roller axis along the straight line segment O in the second embodiment of the present invention is shown. 1-1 O 1-2 Schematic diagram of the movement.

[0050] Fig.13 The first roller axis along the straight line segment O in Example 3 of the present invention is shown. 1-1 O 1-2 The second roller moves along the straight line segment O 2-1 O 2-2 Schematic diagram of the movement.

[0051] Fig.14 The first roller axis along the arc segment O1O in Example 4 of the present invention is shown. 1-1 Schematic diagram of the movement.

[0052] Fig.15 The schematic diagram shown is that the hydraulic device in Example 5 of the present invention pushes the first crystallization roller to move along an inclined straight line.

[0053] Fig.16 The diagram shows the hydraulic device in Example 6 of the present invention pushing the first crystallization roller to move along an arc.

[0054] Fig.17 The first roller axis along the arc segment O in Example 6 of the present invention is shown. 1-1 O 1-2 Schematic diagram of the movement.

[0055] The corresponding relationship between the figure numbers involved in the drawings is as follows:

[0056] 1. The first crystallization roller, 2. The second crystallization roller, 3. The molten pool, 4. The roller gap, 5. The first rotation direction, 6. The water outlet, 7. The casting belt, 8. The straight line where the line segment O1O2 is located, 9. The second rotation direction, 10. The long-range shear thinning interface, 11. The lower limit position, 12. The motion trajectory, 13. The upper limit position, 14. The bearing seat of the first crystallization roller, 15. The bearing seat of the second crystallization roller, 16. The inclined frame, 17. The horizontal frame, 18. The pressing cylinder, 19. The curved frame. DETAILED DESCRIPTION

[0057] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only embodiments of a part of the present invention, rather than all embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present invention.

[0058] In each embodiment: the roller axes of the first crystallization roller 1 and the second crystallization roller 2 are respectively called the first roller axis and the second roller axis, and the roller axis is the rotation axis of the crystallization roller when it rotates. Take any plane φ perpendicular to the first roller axis, and the projection of the first crystallization roller 1 and the second crystallization roller 2 is an ideal circle. On plane φ: when no roller gap 4 floats, the projections of the first roller axis and the second roller axis are points O1 and O2 respectively. When no roller gap 4 floats, the plane formed by the first roller axis and the second roller axis is called the reference plane, and the reference plane is also called plane ψ. The projection of the reference plane on plane φ is the straight line 8 where the line segment O1O2 is located, and the straight line 8 where the line segment O1O2 is located is fixed during the floating process of the roller gap 4. During the floating process of the roller gap 4, at least one of the first crystallization roller 1 and the second crystallization roller 2 is driven by a driving device to move, so that it becomes a moving roller to allow the roller gap 4 to float. The surface swept by the roller axis of the moving roller is called the motion trajectory 12. The roller axis of the moving roller is called the moving roller axis, the position of the moving roller axis on the straight line 8 where the line segment O1O2 is located is called the reference position, the movement amplitude is the distance between the moving roller axis and the reference position, and the movement frequency is the number of times the moving roller axis passes through the straight line 8 where the line segment O1O2 is located within unit time. Embodiment 1:

[0059] A crystallization roller movement method for a double-roll thin strip process disclosed in Example 1 of the present invention is as follows: Fig.11As shown. In the process of equal diameter horizontal twin-roll casting, first, the first crystallization roller 1 and the second crystallization roller 2 rotate in opposite directions; then, molten steel is continuously injected into the space between the two crystallization rollers through the flow distribution device 6 to form a molten pool 3 with a relatively stable depth; side sealing devices are set at the ends of the two crystallization rollers to support the formation of the molten pool 3, but when the depth of the molten pool 3 is shallow, the side sealing device may not be set; the casting belt 7 moves out of the molten pool 3 through the roller gap 4; in the process of the casting belt 7 moving out of the molten pool 3, the first crystallization roller 1 is driven by the driving device so that the first crystallization roller 1 is a moving roller; the second crystallization roller 2 is a fixed roller; the movement of the first crystallization roller 1 causes the relative position of the two crystallization rollers to change, so as to allow the roller gap 4 to float. The floating of the roller gap 4 causes the long-range shear thinning interface 10 to collapse, so as to weaken the quasi-periodic transmission behavior in the molten pool 3, especially to cause the long-range shear thinning interface 10 to collapse in advance, so as to effectively reduce the peak pressure in the molten pool 3, thereby avoiding a series of process stability problems and casting belt quality problems caused by excessive peak pressure in the molten pool 3.

[0060] As shown in Example 1 of the present invention Fig.11 In the figure, the movement of the first crystallization roller 1 causes the roller gap 4 to float. During the floating process of the roller gap 4, the position of the straight line 8 where O1O2 is located does not change, because O1 and O2 are the projections of the first roller axis and the second roller axis on the plane φ before the first crystallization roller 1 starts to move, and the straight line 8 where O1O2 is located is a reference position relatively still with respect to the ground. During the floating process of the roller gap 4, the surface swept by the first roller axis is the motion trajectory 12, and the projection of the motion trajectory 12 on the plane φ is the straight line segment O1O2. 1-1 During the floating process of the roller gap 4, the moving direction of the first crystallization roller 1 is always oblique to the straight line 8 where the line segment O1O2 is located, and the oblique angle is δ, δ=15 degrees.

[0061] As shown in Example 1 of the present invention Fig.11 In the plane φ, the first roller axis is at O1O 1-1 Movement on a line segment, O1O 1-1 The straight line where the line segment is located intersects obliquely with the straight line 8 where the line segment O1O2 is located, and the oblique angle δ is 15 degrees.

[0062] As shown in Example 1 of the present invention Fig.11 In the plane φ, the first roller axis is at O1O 1-1 The motion on a line segment can be periodic, non-periodic, or a combination of periodic and non-periodic.

[0063] As shown in Example 1 of the present invention Fig.11 In the plane φ, the first roller can reach O1O 1-1 After any point on the line segment (including O 1-1 points, but not including point O1), that is, return to O1.

[0064] As shown in Example 1 of the present invention Fig.11 In the plane φ, the first roller can be moved linearly to O 1-1 , or it can move to O through an arc 1-1 .

[0065] As shown in Example 1 of the present invention Fig.11 In the figure, the movement amplitude of the first crystallization roller 1 is the straight line segment O1O 1-1 The length of the straight line segment O1O 1-1 The length ranges from 20 to 50 microns.

[0066] As shown in Example 1 of the present invention Fig.11 In the embodiment, the movement frequency of the first crystallization roller 1 is in the range of 0.01 to 9 Hz, and the movement frequency may vary in a sinusoidal manner.

[0067] As shown in Example 1 of the present invention Fig.11 In the embodiment, the first roller moves on the motion track 12, and the motion amplitude may vary in a sinusoidal manner.

[0068] As shown in Example 1 of the present invention Fig.11 In the embodiment, the first roller moves on the motion track 12, and the motion speed may vary in a sinusoidal manner.

[0069] The skew angle is related to the composition of the cast metal. When other process parameters are fixed, the wider the two-phase region of the cast metal, the larger the skew angle should be.

[0070] Optionally, in Embodiment 1 of the present invention, the skew angle δ is in the range of 3 to 60 degrees.

[0071] Optionally, in Embodiment 1 of the present invention, the skew angle δ is in the range of 6 to 15 degrees.

[0072] Optionally, in Example 1 of the present invention, on the plane φ, the motion trajectory of the first roller is a combination of straight line segments and / or arc segments.

[0073] The beneficial effects of Example 1 of the present invention can be preliminarily confirmed by numerical simulation. The casting speed is in the range of 30 to 60 m / min, the roller diameters of the two crystallization rollers are both 400 mm, the molten pool depth is 125 to 135 mm, the superheat of the melt entering the molten pool 3 is in the range of 20 to 60 degrees Celsius, the skew angle is in the range of 3 to 60 degrees, the movement frequency of the first crystallization roller 1 is in the range of 2 to 10 Hz, the movement amplitude of the first crystallization roller 1 is in the range of 10 to 200 microns, and the peak pressure at the bottom of the molten pool 3 can be reduced by 3 to 72%. However, it should also be acknowledged that the numerical simulation method is based on a large number of assumptions, and the current mathematical model cannot be experimentally confirmed. The results obtained by numerical simulation are only a valuable reflection of the actual effect and can be used to predict the actual trend.

[0074] The beneficial effects of embodiment 1 of the present invention are as follows: Figure 2 and attached Figure 3 Compared with the conventional method shown, it can more effectively promote the early collapse of the long-range shear thinning interface 10 in the molten pool 3 and reduce the peak pressure. The reduction of peak pressure can not only avoid various process stability problems, but also reduce the wear of the crystallization roller, increase the service life of key equipment, and thus significantly reduce production costs.

[0075] The embodiment of the present invention is shown Fig.11 It is an equal-diameter horizontal twin-roll casting mill, and the casting belt 7 is moved out of the molten pool 3 from the bottom. The twin-roll casting mill in the present invention not only refers to an equal-diameter casting mill, but can also be a different-diameter twin-roll casting mill, and can also be a variable-diameter twin-roll casting mill. The variable-diameter twin-roll casting mill can be used to prepare composite pipes, composite bars, composite plates and other coating materials. The two crystallization rollers can be placed horizontally, tilted or vertically. The casting belt 7 can be moved out of the molten pool 3 along the direction of gravity, and can be moved out of the molten pool 3 at an angle less than 180 degrees to the direction of gravity, and can even be moved out of the molten pool 3 in a direction completely opposite to the direction of gravity. Embodiment 2:

[0076] A crystallization roller movement method for a double-roll thin strip process disclosed in Example 2 of the present invention is as follows: Fig.12 shown.

[0077] Embodiment 2 of the present invention is an improved embodiment of Embodiment 1.

[0078] The embodiment of the present invention is shown Fig.12 In the plane φ, the first roller axis is at O 1-1 O 1-2 Movement on a line segment. 1-1 Line segments and O1O 1-2 The lengths of the line segments can be the same or different. 1-1 After reaching any point on the line segment, you can move back to O1. 1-1 O 1-2 The straight line where the line segment is located intersects the straight line 8 where the line segment O1O2 is located obliquely, and the oblique angle is δ, which is 5 degrees.

[0079] The embodiment of the present invention is shown Fig.12 It is an equal-diameter horizontal twin-roll casting and rolling mill, and the cast belt 7 is led out from the bottom. Embodiment 3:

[0080] Embodiment 3 of the present invention discloses a crystallization roller movement method for a double-roll thin strip process, such as Fig.13 shown.

[0081] Embodiment 3 of the present invention is an improved embodiment of Embodiment 1 and Embodiment 2.

[0082] As shown in Example 3 of the present invention Fig.13 In the plane φ, the first roller axis is at O 1-1 O 1-2 The second roller moves on the line segment. 2-1 O 2-2 Movement on a line segment. 1-1 O 1-2 The straight line where the line segment is located intersects the straight line 8 where the line segment O1O2 is located obliquely, and the oblique angle is δ. 2- 1O 2-2 The straight line where the line segment is located is obliquely intersected with the straight line 8 where the line segment O1O2 is located, and the oblique angle is η. The oblique angle δ is the same as the oblique angle η.

[0083] Optionally, as shown in Example 3 of the present invention Fig.13 In the embodiment, the skew angle δ and the skew angle η may be different. Embodiment 4:

[0084] A crystallization roller movement method for a double-roll thin strip process disclosed in Example 4 of the present invention is as follows: Fig.14 shown.

[0085] Example 4 of the present invention Fig.14 In the figure, the first crystallization roller 1 is a moving roller, and the second crystallization roller 2 is a fixed roller. The first crystallization roller 1 moves along a preset motion trajectory 12, and the motion trajectory 12 is an arc segment. The oblique angle between the tangent of a certain point on the motion trajectory 12 (excluding the end point) and the straight line 8 where the line segment O1O2 is located is δ. The casting belt 7 is drawn out from the bottom.

[0086] The beneficial effect of embodiment 4 of the present invention is that Figure 2 and attached Figure 3 Compared with the conventional method shown, the method shown in Example 4 of the present invention can more efficiently cause the collapse of the long-range shear thinning interface 3 while reducing the thickness fluctuation of the cast strip 7.

[0087] The starting point of Example 4 of the present invention is that the change of the pressure in the molten pool 3 should be as stable as possible, and changing the pressure in the molten pool 3 too quickly is not conducive to process stability. Compared with Examples 1 to 3 of the present invention, the beneficial effect is that the pressure change rate in the molten pool 3 is significantly reduced, and the pressure in the molten pool 3 can be further suppressed from changing too quickly, avoiding the process stability problem caused by the pressure change in the molten pool 3 too quickly, and further optimizing the process stability.

[0088] In Example 4 of the present invention, the movement amplitude of the moving roller is in the range of 2 to 62 micrometers, and the movement frequency is in the range of 0.01 to 12 Hz. Embodiment 5:

[0089] Embodiment 5 of the present invention discloses a crystallization roller motion device for a double-roll thin strip process, such as Fig.15 As shown, the effect produced is as in Example 1 Fig.11 and Example 2 Fig.12 shown.

[0090] As shown in Example 5 of the present invention Fig.15 In the figure, the first crystallization roller 1 is connected to the frame 10 through the first crystallization roller bearing seat 14, the second crystallization roller 2 is connected to the frame through the second crystallization roller bearing seat 15, and the frame includes an inclined frame 16 and a horizontal frame 17; a roller gap 4 is left between the first crystallization roller 1 and the second crystallization roller 2; the first crystallization roller 1 is a moving roller; the first crystallization roller 1 is connected to the pressing cylinder 18, and under the action of the pressing cylinder 18, on the plane φ, the motion trajectory of the first roller shaft is obliquely intersected with the straight line 8 where O1O2 is located, and the straight line 8 where O1O2 is located is the projection of the plane ψ on the plane φ, the plane ψ is perpendicular to the plane φ, and the plane φ is the paper surface.

[0091] As shown in Example 5 of the present invention Fig.15 In the figure, the slope of the inclined frame 16 is different from the straight line 8 where O1O2 is located. Taking the horizontal plane as a reference, on the plane φ, the left side is lower and the right side is higher, which is a positive slope. The slope of the straight line 8 where O1O2 is located is zero degrees, and the slope of the inclined frame 16 is θ, θ=+15 degrees. In the actual casting process, the inclined frame 16 will be deformed, and this deformation will cause θ to change to a certain extent.

[0092] As shown in Example 5 of the present invention Fig.15 The preferred values ​​of angle θ are 1.5 to 15 degrees and 30 to 45 degrees: for steel materials, the preferred value of angle θ is in the range of 1.5 to 15 degrees, because the thermal conductivity of steel materials is low, the long-range shear thinning interface is short, and it is located at the bottom of the molten pool; for non-ferrous metal materials, especially when preparing multi-layer thin strips, the preferred value of angle θ is in the range of 30 to 45 degrees, because the two-phase region of non-ferrous metals is wide, and the long-range shear thinning interface extends from the bottom of the molten pool to the middle of the molten pool. The size of θ is related to the process parameters such as the composition and superheat of the cast metal, the depth of the molten pool, and the casting speed. When other process parameters are fixed, the wider the two-phase region of the cast metal is, the larger θ should be.

[0093] As shown in Example 5 of the present invention Fig.15 In the embodiment, under the constraint of the tilting frame 16, the surface swept by the first roller is a plane, and the movement amplitude of the first roller does not exceed 0.12 mm.

[0094] As shown in Example 5 of the present invention Fig.15 In the embodiment, the pressing cylinder 18 is a hydraulic drive device. Embodiment 6:

[0095] Embodiment 6 of the present invention discloses a crystallization roller motion device for a double-roll thin strip process, such as Fig.16 As shown, the effect of Example 6 of the present invention is as follows Fig.17 The effect of the sixth embodiment of the present invention can also be the same as that of the fourth embodiment. Fig.14 shown.

[0096] Example 6 of the present invention Fig.16 In the figure, the first crystallization roller 1 is a moving roller, the second crystallization roller 2 is a fixed roller, the first crystallization roller 1 is connected to the curved frame 19 through the first crystallization roller bearing seat 14, and the second crystallization roller 2 is connected to the horizontal frame 17 through the second crystallization roller bearing seat 15.

[0097] Example 6 of the present invention Fig.16 In the embodiment, the slope of the curved frame 19 is continuously changed. During the floating process of the roll gap 4, the first crystallization roll 1 is driven to move by the pressing cylinder 18. Under the constraint of the curved frame 19, the motion track 12 swept by the first roll axis is a curved surface, such as Fig.17 As shown. A track is provided on the curved frame 19 to allow the first crystallization roller bearing seat 14 to move with low resistance. The pressing cylinder 18 can be replaced by other devices to provide a more complex force form to the first crystallization roller 1.

[0098] Example 6 of the present invention Fig.16 In the figure, when the first roller is located at the reference plane 8, the oblique angle between the movement direction of the first roller and the reference plane 8 is θ, θ=15°. Due to the horizontal equal-diameter twin-roll casting, during the floating process of the roller gap 4, when the first crystallization roller 1 approaches the second crystallization roller 2, θ becomes larger; when the first crystallization roller 1 moves away from the second crystallization roller 2, θ becomes smaller.

[0099] Example 6 of the present invention Fig.16 In the embodiment, the surface swept by the first roller is a curved surface, and the curved surface is generated by the design geometry of the frame. The plane where the motion trajectory of the first roller is located is a series of tangent planes.

[0100] Example 6 of the present invention Fig.17 In the middle, arc segment O1O 1-2 The length of the arc segment O1O is greater than 1-1 Length.

[0101] Optionally, in Example 6 of the present invention, when the first roller passes through the reference plane, the speed (or the tangent plane of the trajectory) is orthogonal to the reference plane (or plane ψ); when the first roller leaves the reference plane, the speed direction (or the tangent plane of the trajectory) is oblique to the reference plane (or plane ψ).

[0102] Optionally, in Example 6 of the present invention, a track is provided in the contact area between the frame and the bearing seat, and a rolling bearing may also be provided to reduce the resistance of the bearing seat during movement.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A crystallization roller movement method for a double-roll thin strip process, wherein the roller axes of a first crystallization roller (1) and a second crystallization roller (2) are respectively referred to as the first roller axis and the second roller axis, the first crystallization roller (1) and the second crystallization roller (2) rotate in opposite directions, molten steel is continuously injected into the space between the two crystallization rollers through a flow distribution device (6) to form a molten pool (3), and a cast strip (7) is removed from the molten pool (3) through a roller gap (4); taking any plane φ perpendicular to the roller axis of the first crystallization roller (1), the projection of the first crystallization roller (1) on the plane φ is a circle with point O1 as the center, and the projection of the second crystallization roller (2) on the plane φ is a circle with point O2 as the center; In plane φ: when no roller gap (4) floating occurs, the projections of the first roller axis and the second roller axis are points O1 and O2 respectively; when no roller gap (4) floating occurs, the plane formed by the first roller axis and the second roller axis is called the reference plane, and the projection of the reference plane on plane φ is the straight line (8) where the line segment O1O2 is located, and the straight line (8) where the line segment O1O2 is located is fixed during the roller gap (4) floating process; it is characterized by: In the process of the casting strip (7) moving out of the molten pool (3), the first crystallization roller (1) or the second crystallization roller (2) is driven to be a moving roller, and the movement of the moving roller causes the relative position of the two crystallization rollers to change, so as to allow the roller gap (4) to float; the position relationship between the movement trajectory (12) of the center of the projection of the moving roller on the plane φ and the straight line (8) where the line segment O1O2 is located is oblique, and the floating of the roller gap (4) causes the long-range shear thinning interface to collapse in advance and weakens the quasi-periodic transmission behavior in the molten pool; The oblique intersection angle between the motion trajectory (12) and the line segment O1O2 is in the range of 3 to 60 degrees, the motion amplitude of the motion roller is in the range of 2 to 62 micrometers, and the motion frequency is in the range of 0.01 to 12 Hz.

2. A crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: The motion trajectory (12) of the center of the projection of the moving roller on the plane φ is a straight line segment.

3. The crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: The motion trajectory (12) of the center of the projection of the moving roller on the plane φ is an arc segment.

4. The crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: The motion trajectory (12) of the center of the projection of the moving roller on the plane φ is a combination of a straight line segment and an arc segment.

5. The crystallization roller movement method for a double-roll thin strip process according to claim 2, characterized in that: The skew angle is in the range of 6 degrees to 15 degrees.

6. The crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: During the movement of the moving roller, the skew angle is variable or constant.

7. The crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: The movement of the moving roller may be periodic or non-periodic.

8. The crystallization roller movement method for a double-roll thin strip process according to claim 1, characterized in that: The movement amplitude of the moving roller changes in a sinusoidal manner, and the movement speed of the moving roller changes in a sinusoidal manner; the movement frequency of the moving roller is in the range of 2 to 10 Hz.

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