Crystallizer for continuous casting of hypereutectic aluminum-silicon alloy and casting method thereof

Abstract

The invention belongs to the technical field of semi-continuous casting, and particularly relates to a crystallizer for continuous casting of hypereutectic aluminum-silicon alloy and a casting method thereof.The crystallizer for continuous casting of hypereutectic aluminum-silicon alloy comprises a crystallizer body with a barrel-shaped inner cavity and an annular cooling structure embedded in the barrel-shaped inner cavity; the annular cooling structure is of a two-section composite structure and comprises a silicon carbide ring and a graphite ring which are connected up and down, and the silicon carbide ring is arranged close to the melt inlet end of the crystallizer; the graphite ring is respectively communicated with a gas supply system and an oil supply system, and a layer of oil gas film is formed between the graphite ring and the alloy casting rod. An annular cooling structure adopted in the crystallizer is of a two-section composite structure with a silicon carbide ring and a graphite ring, the defects of cold shut, coarse grain layers, segregation, casting knots and the like on the surface of a casting rod can be overcome, and the high-quality hypereutectic aluminum-silicon alloy casting rod is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of semi-continuous casting, and specifically relates to a crystallizer for continuous casting of a hypereutectic aluminum-silicon alloy and a casting method thereof. Background Art

[0002] Hypereutectic aluminum-silicon alloys have been widely used in the automotive manufacturing field due to their low density, small solidification shrinkage, low thermal expansion coefficient and good wear resistance. Compared with traditional hypoeutectic and eutectic aluminum-silicon alloys, hypereutectic aluminum-silicon alloys have better material strength and wear resistance, and can meet the needs of higher speeds and higher powers such as engines, transmission cases and transmissions. However, the high silicon content of hypereutectic aluminum-silicon alloys makes its crystallization latent heat much greater than that of traditional cast aluminum alloys, which increases the difficulty of its continuous casting industrialization.

[0003] In the processing of hypereutectic aluminum-silicon alloy, the quality of the ingot produced by the semi-continuous casting method has a great influence on the quality of subsequent processing steps. Among them, the crystallizer is the most critical component. Its main function is to cool and crystallize the aluminum liquid. The structure of the crystallizer directly affects the surface quality and internal quality of the ingot.

[0004] Since hypereutectic aluminum-silicon alloy has a higher latent heat of crystallization than traditional aluminum alloys, which is four times that of traditional aluminum alloys, if it is not cooled in time, it will cause secondary heating and remelting around the high-silicon aluminum alloy ingot, causing the originally solidified shell to melt, resulting in defects such as bending deformation, cracks, cold shut, coarse grain layer, bubbles, and thick segregation nodules, thereby reducing the quality of the final hypereutectic aluminum-silicon alloy product.

[0005] At present, the semi-continuous casting of hypereutectic aluminum-silicon alloy still uses traditional crystallizers or oil-gas lubricated crystallizers, but due to their limited cooling capacity and surface lubrication capacity, the quality of the final hypereutectic aluminum-silicon alloy product is reduced. Therefore, the existing crystallizers for casting hypereutectic aluminum-silicon alloys still need to be improved. Summary of the invention

[0006] The main purpose of the present invention is to propose a crystallizer for continuous casting of hypereutectic aluminum-silicon alloy and a casting method thereof. The annular cooling structure used in the crystallizer of the present invention is a two-stage composite structure having a silicon carbide ring and a graphite ring, which can improve defects such as cold shut, coarse grain layer, segregation, and casting nodules on the surface of the cast rod, and obtain high-quality hypereutectic aluminum-silicon alloy cast rods.

[0007] A first aspect of the present invention provides a crystallizer for continuous casting of hypereutectic aluminum-silicon alloys, which includes a crystallizer body having a cylindrical inner cavity, and an annular cooling structure embedded in the cylindrical inner cavity; the annular cooling structure is a two-stage composite structure, including a silicon carbide ring and a graphite ring connected upper and lower, and the silicon carbide ring is arranged near the melt inlet end of the crystallizer; the graphite ring is respectively connected to the air supply system and the oil supply system, and a layer of oil and gas film is formed between the graphite ring and the alloy casting rod.

[0008] In some embodiments of the present invention, the graphite ring is provided with an air groove connected to the air supply system, and an oil groove connected to the oil supply system.

[0009] In some embodiments of the present invention, the oil groove is arranged on a side of the graphite ring close to the silicon carbide ring, and the ventilation groove is arranged in the middle of the graphite ring.

[0010] In some embodiments of the present invention, an air inlet channel is provided on the crystallizer body to connect the air supply system with the ventilation groove, and an oil inlet channel is provided to connect the oil supply system with the oil groove.

[0011] In some embodiments of the present invention, the apertures of the air inlet channel and the oil inlet channel are independently 1.5 mm to 2.5 mm.

[0012] In some embodiments of the present invention, the silicon carbide ring is provided with an insert block, the graphite ring is correspondingly provided with a slot, and the silicon carbide ring is snap-connected with the graphite ring to form the annular cooling structure.

[0013] In some embodiments of the present invention, a water spray hole is provided on the crystallizer body, and the water spray hole is located below the graphite ring, for cooling the alloy cast rod.

[0014] The second aspect of the present invention provides a casting method for a hypereutectic aluminum-silicon alloy, and the casting method is based on the crystallizer for continuous casting of the hypereutectic aluminum-silicon alloy described in the first aspect; the casting method comprises: pouring a hypereutectic silicon-aluminum alloy melt at a preset temperature; the hypereutectic silicon-aluminum alloy melt flows into the crystallizer and casting begins; when the length of the cast rod is 200mm to 400mm, ventilation and pulse oiling are turned on to form an oil-gas film on the graphite ring; the hypereutectic silicon-aluminum alloy melt first passes through a silicon carbide ring for preliminary cooling, shell solidification and pre-crystallization, and then is subsequently cooled through the oil-gas film formed on the graphite ring; after the casting is completed, a hypereutectic silicon-aluminum alloy cast rod is obtained.

[0015] In some embodiments of the present invention, during the casting process, the casting temperature is controlled at 680°C to 720°C.

[0016] In some embodiments of the present invention, during ventilation, the air pressure is controlled at 0.3 MPa to 0.5 MPa.

[0017] In some embodiments of the present invention, the continuous casting speed is controlled to be 180 mm / min to 250 mm / min.

[0018] In some embodiments of the present invention, the pouring temperature is 800°C to 820°C.

[0019] In some embodiments of the present invention, during the casting process, cooling water is sprayed through the water spray holes to continuously cool the alloy cast rods, and the cooling water flow rate is controlled to be 450L / min to 550L / min.

[0020] The annular cooling structure adopted in the present invention is a two-stage composite structure having a silicon carbide ring and a graphite ring, which is used to replace the graphite ring cooling structure in the traditional crystallizer. It can improve the defects such as cold shut, coarse grain layer, segregation, and casting nodules on the surface of the cast rod, and obtain high-quality hypereutectic aluminum-silicon alloy cast rods.

[0021] In the present invention, the annular cooling structure is firstly improved in structure, and the annular cooling structure is not a superposition of a silicon carbide ring and a graphite ring with a single function, and it also has strict requirements on process parameters. In order to achieve the necessary surface and internal quality optimization effect, the two-stage composite annular cooling structure and the casting process parameters need to be precisely controlled and coordinated at the same time; and the molten liquid cannot destroy the oil and gas film generated on the inner wall of the graphite ring during the solidification process, so there are also high requirements for the setting and stability of the air pressure.

[0022] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference numerals are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0024] Figure 1 Schematic diagram of the structure of a crystallizer for continuous casting of a hypereutectic aluminum-silicon alloy according to some embodiments of the present invention;

[0025] Figure 2 for Figure 1 Schematic diagram of the cross section in the AA direction;

[0026] Figure 3 A schematic diagram of connecting a silicon carbide ring and a graphite ring according to some embodiments of the present invention;

[0027] Figure 4 This is a surface diagram of a cast rod produced by continuous casting in Example 1 of the present invention;

[0028] Figure 5 A surface diagram of a cast rod produced by continuous casting in the prior art;

[0029] Figure 6 The metallographic structure diagram of the cast rod produced by continuous casting in Example 1 of the present invention;

[0030] Figure 7 This is a metallographic structure diagram of a cast rod produced by continuous casting in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 100. Crystallizer for continuous casting of hypereutectic aluminum-silicon alloy;

[0033] 10. Crystallizer body; 11. Air inlet channel; 12. Oil inlet channel;

[0034] 20. Annular cooling structure; 21. Silicon carbide ring; 22. Graphite ring;

[0035] 30. Card slot; 40. Insert block; 50. Water spray hole. DETAILED DESCRIPTION

[0036] The exemplary embodiments of the present invention will be described in more detail below with reference to specific embodiments. It should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0038] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0039] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship.

[0041] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0042] In the description of the embodiments of the present invention, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the embodiments of the present invention.

[0043] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0044] When using traditional crystallizers to produce cast rods, it is easy to produce deep cold shuts, too thick segregation layers, and surface scratches, which require more peeling and removal for subsequent use, resulting in material waste. Although the above problems can be improved by using oil-gas sliding crystallizers for conventional aluminum alloys, hypoeutectic silicon and eutectic aluminum-silicon alloys, the hypereutectic aluminum-silicon alloy has a higher latent heat of crystallization, making it difficult to form a stable oil-gas film structure. Therefore, the existing oil-gas sliding crystallizer cannot significantly improve the problems of cold shut, segregation, and casting nodules existing in hypereutectic aluminum-silicon alloy cast rods.

[0045] In order to solve the above problems, the present invention provides a hypereutectic aluminum-silicon alloy continuous casting crystallizer for preparing hypereutectic aluminum-silicon alloy cast rods. The annular cooling structure adopted by the hypereutectic aluminum-silicon alloy continuous casting crystallizer is a two-stage composite structure, which has a silicon carbide ring and a graphite ring.

[0046] Crystallizer graphite ring is an important equipment used for industrial crystal growth and has been widely used.

[0047] Silicon carbide is a highly thermally conductive material with a large number of tiny holes on its surface, which can increase the surface area and improve the efficiency of heat dissipation. The thermal conductivity of silicon carbide is higher than that of copper, so the heat generated at high temperature will be quickly transferred to the surface of silicon carbide and dissipated. In addition, silicon carbide materials can withstand high temperature and high pressure environments and are suitable for various harsh environments. Although silicon carbide and graphite have their own advantages and disadvantages in thermal stability, in general, silicon carbide has better thermal stability. Thermal stability will affect the temperature control of crystal growth. The higher the thermal stability, the more accurate the temperature control of crystal growth.

[0048] See also Figure 1 to Figure 2 As shown, the hypereutectic aluminum-silicon alloy continuous casting crystallizer 100 provided by the present invention includes a crystallizer body 10 with a cylindrical inner cavity, and an annular cooling structure 20 embedded in the cylindrical inner cavity; wherein the annular cooling structure 20 is a two-stage composite structure, including a silicon carbide ring 21 and a graphite ring 22 connected upper and lower, and the silicon carbide ring 21 is arranged near the melt inlet end of the crystallizer; the graphite ring 22 is respectively connected to the air supply system and the oil supply system, and a layer of oil and gas film is formed between the graphite ring 22 and the alloy casting rod.

[0049] In the embodiment of the present invention, a two-stage composite annular cooling structure 20 is used to replace the graphite ring cooling structure in the traditional crystallizer to improve the defects of cold shut, coarse grain layer, segregation, casting nodules, etc. on the surface of the cast rod, and obtain high-quality hypereutectic aluminum-silicon alloy cast rods. Specifically, after the molten metal enters the crystallizer, it first contacts with the silicon carbide ring 21. By utilizing the excellent thermal stability of silicon carbide, the heat loss of the molten metal through the silicon carbide ring 21 is reduced, and a pre-crystallized structure is first formed on the ingot, which solves the problem of poor stability of the solidified shell and easy damage of the oil and gas film caused by the excessively high crystallizer latent heat of the hypereutectic aluminum-silicon alloy when the ingot directly contacts the oil and gas talc graphite ring 22, and the surface finish of the ingot is further improved by the two-stage composite cooling structure.

[0050] In an embodiment of the present invention, a ventilation groove connected to the air supply system and an oil groove connected to the oil supply system are provided on the graphite ring 22. The ventilation groove and the oil groove are provided to drain and temporarily store gas and oil, thereby stably forming a layer of oil and gas film on the inner side of the graphite ring 22.

[0051] Continue to see Figure 2 As shown, the graphite ring 22 is provided with an air groove and an oil groove. The oil groove is arranged at the upper end of the graphite ring 22, that is, at the side close to the silicon carbide ring 21; the air groove is arranged in the middle of the graphite ring 22, and the gas and oil enter the graphite ring 22 through the air groove and the oil groove respectively, and form a layer of oil and gas film on the inner side of the graphite ring 22.

[0052] In the embodiment of the present invention, the ventilation groove is provided on the outer wall of the graphite ring 22 along the circumference of the graphite ring 22 , and the outer wall of the graphite ring 22 is a side wall close to the cylindrical inner cavity wall of the crystallizer body 10 .

[0053] In the embodiment of the present invention, the oil passage groove is provided on the outer side wall of the graphite ring 22 along the circumference of the graphite ring 22, and the oil passage groove and the ventilation groove are provided independently of each other.

[0054] Continue to see Figure 2 As shown, the crystallizer body 10 is provided with an air inlet channel 11 and an oil inlet channel 12 to correspond to the air vent and the oil vent on the graphite ring 22 respectively.

[0055] In the embodiment of the present invention, the crystallizer body 10 is provided with an air inlet channel 11 to connect the air supply system with the air vent, and an oil inlet channel 12 to connect the oil supply system with the oil vent.

[0056] In an embodiment of the present invention, the apertures of the air inlet channel 11 and the oil inlet channel 12 are independently 2±0.5 mm, i.e., 1.5 mm to 2.5 mm. For example, the aperture of the air inlet channel 11 can be one of 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, or any value that satisfies the above range. The aperture of the oil inlet channel 12 can be one of 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, or any value that satisfies the above range.

[0057] Continue to see Figure 3 As shown, an insert block 40 is provided on the silicon carbide ring 21, and a clamping groove 30 is correspondingly provided on the graphite ring 22. The silicon carbide ring 21 and the graphite ring 22 are clamped together to form an annular cooling structure.

[0058] In an embodiment of the present invention, the annular cooling structure 20 is a two-stage composite structure, and the silicon carbide ring 21 and the graphite ring 22 are combined in the form of a slot to form the two-stage composite structure, which is used for cooling the melt once.

[0059] Continue to see Figure 2 As shown, a water spray hole 50 is provided on the crystallizer body 10, and the water spray hole 50 is located below the graphite ring 22, and is used to cool the alloy cast rod.

[0060] In the embodiment of the present invention, the water spray holes 50 are arranged on the inner cavity wall of the crystallizer body 10 and arranged in an array along its circumference for secondary cooling of the alloy cast rods.

[0061] The present invention also provides a casting method for hypereutectic aluminum-silicon alloy. The key is that the casting method is based on the above-mentioned hypereutectic aluminum-silicon alloy continuous casting crystallizer, and through the design of an annular cooling structure and precise control of casting process parameters, the effect of improving the surface and internal quality of the casting is achieved.

[0062] The casting method of the hypereutectic aluminum-silicon alloy in the present invention is carried out according to the following steps.

[0063] 1) Melt the hypereutectic silicon aluminum alloy melt.

[0064] In an embodiment of the present invention, a hypereutectic silicon-aluminum alloy ingot is melted in a melting furnace to obtain a hypereutectic silicon-aluminum alloy melt.

[0065] In an embodiment of the present invention, the melting temperature is 800° C. to 900° C. For example, the melting temperature may be 800° C., 810° C., 820° C., 830° C., 840° C., 850° C., 860° C., 870° C., 880° C., 890° C., 900° C., or any value satisfying the above range.

[0066] 2) Deterioration treatment.

[0067] In an embodiment of the present invention, the melt is subjected to a transformation treatment in a melting furnace.

[0068] 3) Degassing and slag removal.

[0069] In an embodiment of the present invention, the melt is transferred to a holding furnace, the holding temperature of the holding furnace is set to 780°C to 840°C, and degassing and deslagging are performed in the holding furnace. Exemplarily, the holding temperature may be one of 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, or any value that satisfies the above range.

[0070] 4) Pouring.

[0071] In an embodiment of the present invention, the temperature of the melt is controlled to be 800° C. to 820° C. for pouring. For example, the pouring temperature may be 800° C., 810° C., 820° C., or any value within the above range.

[0072] 5) Casting.

[0073] In an embodiment of the present invention, the molten metal flows into the crystallizer through the diverter plate to start casting, and the casting temperature is controlled at 680° C. to 720° C. For example, the casting temperature may be one of 680° C., 690° C., 700° C., 710° C., 720° C., or any value satisfying the above range.

[0074] In an embodiment of the present invention, when the length of the cast rod is 200mm to 400mm, ventilation and pulse oil are turned on, the air pressure is controlled at 0.4±0.1MPa, that is, 0.3MPa to 0.5MPa, the continuous casting speed is controlled at 180mm / min to 250mm / min, and the cooling water flow rate is controlled at 450L / min to 550L / min. Exemplarily, the air pressure can be controlled to be one of 0.3MPa, 0.4MPa, 0.5MPa or any value satisfying the above range value. The continuous casting speed can be controlled to be one of 180mm / min, 190mm / min, 200mm / min, 210mm / min, 220mm / min, 230mm / min, 240mm / min, 250mm / min or any value satisfying the above range value. The cooling water flow rate can be controlled to be one of 450L / min, 460L / min, 470L / min, 480L / min, 490L / min, 500L / min, 510L / min, 520L / min, 530L / min, 540L / min, 550L / min or any value that meets the above range.

[0075] In an embodiment of the present invention, the crystallizer annular cooling structure 20 is of segmented design. The melt first passes through the silicon carbide ring 21 for preliminary cooling, shell solidification and pre-crystallization, and then passes through the "oil-gas film" formed on the graphite ring 22 for subsequent cooling. The "oil-gas film" is formed by oil and gas passing through the air inlet channel 11 and the oil inlet channel 12 and evenly sprayed through the micro-channels inside the graphite ring 22, and then continuously cooled under the action of secondary cooling water.

[0076] 6) After the casting is completed, a hypereutectic silicon aluminum alloy cast rod is obtained.

[0077] In the embodiment of the present invention, the setting of the annular cooling structure is not just a single function superposition of the silicon carbide ring and the graphite ring, and it has strict requirements on the process parameters. In order to achieve the necessary surface and internal quality optimization effect, the two-stage composite annular cooling structure and casting process parameters need to be precisely controlled and coordinated at the same time; and the molten liquid cannot destroy the oil and gas film generated on the inner wall of the graphite ring during the solidification process, so there are also high requirements for the setting and stability of the air pressure.

[0078] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the amounts of the experimental reagents, unless otherwise specified, are the amounts of reagents used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0079] Example 1

[0080] A casting method for a hypereutectic aluminum-silicon alloy, the casting method is based on Figure 1-Figure 3 The hypereutectic aluminum-silicon alloy continuous casting crystallizer shown. The casting method of the hypereutectic aluminum-silicon alloy comprises the following steps:

[0081] 1) Melting a hypereutectic silicon aluminum alloy ingot in a melting furnace to obtain a hypereutectic silicon aluminum alloy melt, the melting temperature of which is 860°C.

[0082] 2) The melt is subjected to a modification treatment in a melting furnace.

[0083] 3) Set the holding temperature of the holding furnace to 800°C and perform degassing and deslagging in the ladle.

[0084] 4) The melt temperature is controlled at 810°C for pouring.

[0085] 5) The molten metal flows into the crystallizer through the diverter plate and starts casting. The casting temperature is controlled at 700°C. When the length of the cast rod is 200mm, ventilation and pulse oiling are turned on, the air pressure is controlled at 0.4MPa, the continuous casting speed is controlled at 200mm / min, and the cooling water flow is controlled at 500L / min.

[0086] The crystallizer annular cooling structure 20 is of segmented design. The melt first passes through the silicon carbide ring 21 for preliminary cooling, shell solidification and pre-crystallization, and then passes through the "oil-gas film" formed on the graphite ring 22 for subsequent cooling. The "oil-gas film" is formed on the graphite ring 22 by oil and gas through oil holes and air holes, and then is continuously cooled under the action of secondary cooling water.

[0087] 6) After the casting is completed, a hypereutectic silicon aluminum alloy cast rod is obtained.

[0088] In the embodiments of the present invention, the cast rods obtained by casting in Embodiment 1 and the cast rods obtained by casting using a traditional crystallizer in the prior art are simultaneously subjected to metallographic structure analysis using the same equipment and method.

[0089] Combination Figure 6 and Figure 7 It can be seen that the refinement of the primary silicon grains of the cast rod obtained by casting is significantly improved based on the design of the crystallizer and casting process parameters of the present invention based on the annular cooling structure.

[0090] Combination Figure 4 and Figure 5 It can be seen that the surface finish of the cast rods produced by continuous casting of the crystallizer with a two-stage annular cooling structure in the present invention is significantly improved compared with the surface finish of the cast rods produced by continuous casting using the traditional oil-gas lubrication method.

[0091] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A crystallizer for continuous casting of hypereutectic aluminum-silicon alloy, characterized in that: It comprises a crystallizer body having a cylindrical inner cavity, and an annular cooling structure embedded in the cylindrical inner cavity; The annular cooling structure is a two-stage composite structure, including a silicon carbide ring and a graphite ring connected up and down, wherein the silicon carbide ring is arranged near the melt inlet end of the crystallizer; the graphite ring is connected to the air supply system and the oil supply system respectively, and a layer of oil and gas film is formed between the graphite ring and the alloy casting rod.

2. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 1, characterized in that: The graphite ring is provided with an air groove connected to the air supply system, and an oil groove connected to the oil supply system.

3. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 2, characterized in that: The oil groove is arranged on a side of the graphite ring close to the silicon carbide ring, and the ventilation groove is arranged in the middle of the graphite ring.

4. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 1, characterized in that: The crystallizer body is provided with an air inlet passage to connect the air supply system with the ventilation groove, and an oil inlet passage to connect the oil supply system with the oil groove.

5. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 4, characterized in that: The apertures of the air inlet passage and the oil inlet passage are independently 1.5 mm to 2.5 mm.

6. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 1, characterized in that: The silicon carbide ring is provided with an insert block, and the graphite ring is correspondingly provided with a clamping groove, and the silicon carbide ring is clamped with the graphite ring to form the annular cooling structure.

7. The hypereutectic aluminum-silicon alloy continuous casting crystallizer according to claim 1, characterized in that: The crystallizer body is provided with a water spray hole, and the water spray hole is located below the graphite ring, and is used for cooling the alloy cast rod.

8. A method for casting a hypereutectic aluminum-silicon alloy, characterized in that: The casting method is based on the hypereutectic aluminum-silicon alloy continuous casting crystallizer according to any one of claims 1 to 7; the casting method comprises: pouring a hypereutectic silicon-aluminum alloy melt at a preset temperature; The hypereutectic silicon-aluminum alloy melt flows into a crystallizer to start casting; When the length of the casting rod is 200mm-400mm, ventilation and pulse oiling are turned on to form an oil-gas film on the graphite ring; The hypereutectic silicon aluminum alloy melt is first cooled by a silicon carbide ring to form a shell and pre-crystallize, and then cooled by an oil-gas film formed on a graphite ring. After the casting is completed, a hypereutectic silicon aluminum alloy cast rod is obtained.

9. The casting method according to claim 8, characterized in that: During the casting process, the casting temperature is controlled at 680℃~720℃; Preferably, during ventilation, the air pressure is controlled at 0.3MPa to 0.5MPa; Preferably, the continuous casting speed is controlled to be 180 mm / min to 250 mm / min; Preferably, the pouring temperature is 800°C to 820°C.

10. The casting method according to claim 8, characterized in that: During the casting process, cooling water is sprayed through the water spray holes to continuously cool the alloy cast rods, and the cooling water flow rate is controlled to be 450L / min to 550L / min.

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