Graphite ring for aluminum alloy casting crystallizer, preparation method thereof and oil-gas sliding casting method for 6 series aluminum alloy billet

Abstract

The present invention provides a graphite ring for aluminum alloy casting crystallizer, a preparation method thereof and an oil-gas sliding casting method for 6 series aluminum alloy bar blanks. The graphite ring for aluminum alloy casting crystallizer comprises a graphite ring body, a sealing layer and a sealing ring. The graphite ring body has a top wall, an inner wall, an outer wall and a bottom wall. The sealing layer is arranged on the top wall and the bottom wall, and the sealing ring is arranged at the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall; by weight, the graphite ring body comprises 5 to 10 parts of graphite powder, 2 to 3 parts of phenolic resin powder, 1 to 2 parts of modified phenolic resin and 1 to 2 parts of secondary carbon microbeads; the sealing layer and the sealing ring are both silicone polymers. The present invention effectively improves its porosity and thermal conductivity by strictly limiting the composition and structural characteristics of the graphite ring for aluminum alloy casting crystallizer, and at the same time arranging the sealing layer and the sealing ring at specific positions of the graphite ring body.

Description

Technical Field

[0001] The present invention relates to the technical field of semi-continuous casting of aluminum alloys, and in particular to a graphite ring for an aluminum alloy casting crystallizer, a preparation method thereof, and an oil-gas sliding casting method for a 6-series aluminum alloy bar blank. Background Art

[0002] High-performance, high-surface 6xxx aluminum alloys (i.e., 6 series aluminum alloys) are widely used in rail transit, transportation, and 3C fields, which puts strict requirements on the quality of its rods. The annual demand for high-quality 6xxx aluminum alloy rods with thin segregation layers and no peeling is nearly 1 million tons. At present, there are still imperfections in the preparation requirements of high-quality cast rods (especially the extreme thinning of the segregation layer). For example, during the casting process, the oil-gas lubrication effect is unstable, there are occasional defects on the surface of the cast rods, and the lubricating oil overflows from the inner cavity of the crystallizer during long-term use. The main reasons are: 1. The graphite ring of the oil-gas lubrication crystallizer has a low porosity, and the oil and gas supply parameters are not adjusted accordingly during long-term use, and the oil and gas permeability decreases, resulting in unstable oil-gas lubrication effect and surface defects of the cast rods; 2. The graphite ring seal fails during long-term use, resulting in the overflow of lubricating oil from the inner cavity of the crystallizer. The above problems are reflected in the oil-gas sliding casting production of 6xxx aluminum alloy, resulting in a thicker segregation layer (about 140μm~200μm) and uneven internal structure of the 6xxx aluminum alloy bar obtained by casting. The mechanical properties of the product are reduced during the subsequent forging and extrusion process, and defects such as spots appear in the finished product after surface treatment.

[0003] Therefore, there is an urgent need to develop high-performance key components for oil and gas lubricating casting equipment to fundamentally solve the above-mentioned product quality problems.

[0004] Here, it is necessary to explain that the oil-mist lubrication effect is the effect of lubricating and cooling the casting equipment using the oil-mist lubrication (Oil Mist Lubrication) technology during the casting process. The quality of the effect directly affects the cooling rate of the mold and the casting, and then affects the formation of defects such as segregation inside the casting. Oil-mist lubrication casting equipment refers to casting equipment that uses oil and gas as lubrication and cooling media during the alloy casting process. It can reduce the friction resistance of the alloy during the casting process, prevent the alloy from sticking to the mold, and provide appropriate cooling to control the solidification rate of the alloy, thereby improving the surface quality of the casting and the uniformity of the internal structure.

[0005] After investigation and patent review, it is shown that the patents related to oil-gas lubrication casting that have been disclosed are mostly patents for the overall device of oil-gas lubrication casting technology and the structure of crystallizer components, and a few are for the structure and preparation method of graphite rings. For example, the invention patent CN 101733372 B, "Graphite ring for continuous lubrication crystallizer and its manufacturing method", is mainly aimed at ordinary oil-gas lubrication casting graphite rings with a porosity of 12~18%, and does not mention how to prepare high-permeability graphite rings with a porosity of ≥20% through graphite composition and preparation process, nor does it establish the influence relationship between graphite ring performance and oil-gas lubrication casting stability and ingot segregation layer thickness. Invention patent application CN 1903482 A, "A graphite ring for continuous lubrication crystallizer", this patent application uses a single graphite powder to prepare a graphite ring for an oil-gas lubrication crystallizer, and the installation and matching method between the structural design and the crystallizer body. It does not mention the performance parameters of the graphite ring and the key indicators that reflect the oil-gas lubrication effect, that is, the data on the thickness of the segregation layer of the resulting casting. Invention patent CN 100418667 C, "Aluminum and aluminum alloy semi-continuous casting continuous lubrication crystallizer", this patent mainly studies the structure and assembly requirements of oil-gas lubrication casting crystallizer accessories, and focuses on using two rows of water spray holes to improve the secondary water cooling effect, improve the internal structure and surface quality of the ingot, and improve the casting speed and production efficiency. It does not mention the material and processing technology of the graphite ring, and its influence on the oil-gas lubrication effect and the thickness of the ingot segregation layer. Invention patent application CN 111069552 A, "An oil-gas lubrication casting crystallizer", mainly studies the structure and assembly requirements of oil-gas lubrication casting crystallizer accessories. By designing graphite oil rings, graphite gas rings and adapter plate anti-overflow structures, it solves the problems of short service life of graphite rings and bubble overflow during the casting process affecting the quality of the ingot. It also does not mention the influence on the thickness of the segregation layer of the casting ingot. Patent application CN 114393184 A, "An oil-gas lubricated crystallizer that is beneficial to improving the surface quality of aluminum alloy ingots", mainly studies the structure and assembly requirements of oil-gas lubricated casting crystallizer accessories. It mentions that through the use of graphite ring sealing treatment, air leakage can be prevented from causing the liquid surface of the casting plate to roll over, and oxide inclusions inside the ingot can be eliminated, thereby improving the surface quality and internal metallurgical quality of the aluminum alloy ingot. It does not mention the material and processing technology of the graphite ring, and its influence on the oil-gas lubrication effect and the thickness of the ingot segregation layer.

[0006] The above patents have not studied the effects of graphite composition, preparation process, casting oil and gas supply parameters on the porosity, sealing and oil and gas permeability of the finished graphite rings, nor have they established a corresponding relationship between the thickness of the segregation layer of the oil and gas lubricated ingot and the surface quality of the ingot. Therefore, there are still various deficiencies in the overall quality of the resulting castings.

[0007] Based on this, how to provide a high-porosity graphite ring for casting crystallizer and its preparation method so that the oil and gas lubrication effect of the equipment where the obtained graphite ring is located can reach a better state, and then cast a 6 series aluminum alloy casting with superior mechanical properties and surface properties, is one of the important technical problems that need to be solved in this field. Summary of the invention

[0008] The main purpose of the present invention is to provide a graphite ring for an aluminum alloy casting crystallizer, a preparation method thereof and an oil-gas lubrication casting method for a 6-series aluminum alloy rod blank, so as to solve the problem in the prior art that the oil-gas lubrication effect of the equipment in which the graphite ring is located is poor due to the poor performance of the graphite ring for the casting crystallizer, thereby resulting in poor surface properties and mechanical properties of the 6-series aluminum alloy castings obtained by casting.

[0009] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a graphite ring for an aluminum alloy casting crystallizer, which includes a graphite ring body, a sealing layer and a sealing ring. The graphite ring body has a top wall, an inner wall, an outer wall and a bottom wall. The sealing layer is arranged on the top wall and the bottom wall, and the sealing ring is arranged at the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall; in terms of weight, the graphite ring body includes 5 to 10 parts of graphite powder, 2 to 3 parts of phenolic resin powder, 1 to 2 parts of modified phenolic resin and 1 to 2 parts of secondary carbon microbeads; the sealing layer and the sealing ring are both silicone polymers.

[0010] Furthermore, the graphite ring body is a porous structure with a porosity of 15 Vol.% to 30 Vol.%; the thermal conductivity of the graphite ring body is 110 W / (m·K) to 200 W / (m·K).

[0011] Furthermore, the graphite powder is flake graphite powder, and the flake diameter of the flake graphite powder is 100 mesh to 200 mesh; and / or the particle diameter of the secondary carbon microbeads is 15 μm to 20 μm; and / or the modified phenolic resin is epoxy-modified phenolic resin.

[0012] Furthermore, the outer wall of the graphite ring portion body is independently provided with: an oil outlet groove; and a first annular groove and a second annular groove arranged around the graphite ring portion body, and the first annular groove and the second annular groove are both arranged along the circumference of the graphite ring portion body; preferably, starting from the bottom wall, the first annular groove is located at 4 / 19~6 / 19 of the height of the outer wall, and the second annular groove is located at 8 / 19~10 / 19 of the height of the outer wall; and / or, starting from the bottom wall, the oil outlet groove is located at 2 / 3~3 / 4 of the height of the outer wall.

[0013] Preferably, the wall thickness of the graphite ring for the aluminum alloy casting crystallizer is 5mm~8mm; more preferably, the ratio of the depth to the width of the first annular groove is N1, the ratio of the depth to the width of the second annular groove is N2, N1 and N2 are each independently 1:(2~3), the depths of the first annular groove and the second annular groove are each independently 2.0mm~4.0mm; and / or, the specification of the oil outlet groove is Φ2mm~Φ4mm, and the depth is 2.0mm~2.5mm.

[0014] Furthermore, the thickness of the sealing layer is 0.05 mm to 0.15 mm; the thickness of the sealing ring is 0.03 mm to 0.05 mm.

[0015] The second aspect of the present invention provides a method for preparing the above-mentioned graphite ring for aluminum alloy casting crystallizer, comprising: step S1, preparing a graphite ring preform; step S1-1, batching: mixing graphite powder, phenolic resin powder, modified phenolic resin powder and secondary carbon microbeads to obtain a mixed powder; step S1-2, molding: the mixed powder is sequentially pressed and first cured to obtain a graphite ring blank; step S1-3, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-4, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-5, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-6, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-7, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-8, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-9, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-10, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-11, sintering: mixing the graphite powder, phenolic resin powder, modified phenolic resin powder and secondary carbon microbeads to obtain a mixed powder; step S1-2 Step S2, machining the first graphite ring preform into a graphite ring body; step S3, coating the top wall and the bottom wall of the graphite ring body with a silicone sealant, obtaining a pre-sealing layer after a first pre-curing, coating the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall with a silicone sealant, obtaining a pre-sealing ring after a second pre-curing; and then obtaining a second graphite ring preform; step S4, the second graphite ring preform is subjected to a second curing to obtain a graphite ring for an aluminum alloy casting crystallizer.

[0016] Furthermore, in step S1-2, pressing is performed at 90°C to 110°C; the temperature of the first curing is 140°C to 160°C, and the time is 20min to 30min.

[0017] Furthermore, in step S1-3, the sintering temperature is 2200°C to 2800°C, and the time is 5h to 9h; preferably, the sintering is carried out under the protection of an inert gas, and the pressure of the inert gas is 100MPa to 300MPa.

[0018] Furthermore, in step S3, the first pre-curing time is 4h~24h, and / or the second pre-curing time is 12h~36h; preferably, the temperature of the first pre-curing and the second pre-curing is independently 25±2°C.

[0019] Furthermore, in step S4, the temperature of the second curing is 40° C. to 60° C., and the time is 12 h to 24 h.

[0020] The third aspect of the present invention provides an oil-gas sliding casting method for 6 series aluminum alloy billets, wherein the oil-gas sliding casting equipment used in the oil-gas sliding casting method includes an aluminum alloy casting crystallizer, and the aluminum alloy casting crystallizer uses the above-mentioned graphite ring for the aluminum alloy casting crystallizer.

[0021] Furthermore, the graphite ring of the aluminum alloy casting crystallizer is fitted with the inner wall of the aluminum alloy casting crystallizer to form an interference fit, and then the 6 series aluminum alloy billet is cast under the conditions of pulse gas supply and pulse oil supply; and the casting speed is 30mm / min~220mm / min, the casting temperature is 670℃~720℃, and the cooling water flow rate is 2m 3 / h~20m 3 / h; and / or, the pressure of pulse air supply is 0.5MPa~3.0MPa, and the air supply time / interval time is 1:(3~10); and / or, the oil volume of pulse oil supply is 10mL / h~60mL / h, the pressure is 4MPa~8MPa, and the air supply time / interval time is 1:(3~10).

[0022] By applying the technical solution of the present invention, the composition and structural characteristics of the graphite ring for the aluminum alloy casting crystallizer are strictly limited, and a sealing layer and a sealing ring are set at a specific position of the graphite ring body, so as to effectively improve its porosity and thermal conductivity, thereby solving the problems of unstable oil-gas lubrication effect, overflow of lubricating oil in the inner cavity of the crystallizer, thick segregation layer of the obtained casting, and poor mechanical properties during the application process, improving the uniformity of the internal structure of the obtained aluminum alloy oil-gas lubrication ingot, eliminating the coarse grains in its microstructure, and significantly reducing the defects such as spots on its surface, thereby achieving the purpose of improving the comprehensive quality of the aluminum alloy ingot and its subsequent finished parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 This is a scanning electron microscope photograph of the first graphite ring preform obtained in Example 1;

[0025] Figure 2 The schematic diagram of the structure of the graphite ring body obtained in Example 1;

[0026] Figure 3 It is a front view of the graphite ring body obtained in Example 1;

[0027] Figure 4 It is a cross-sectional view of the graphite ring body obtained in Example 1 along the A-A' direction; wherein the reference numerals are as follows: 11, first annular groove; 12, second annular groove;

[0028] Figure 5 This is a metallographic photograph of the 6 series aluminum alloy bar blank obtained in Example 1;

[0029] Figure 6 This is the metallographic structure diagram of the 6 series aluminum alloy bar blank obtained in Example 1;

[0030] Figure 7 This is a scanning electron microscope photograph of the first graphite ring preform obtained in Comparative Example 1;

[0031] Figure 8 This is a scanning electron microscope photograph of the first graphite ring preform obtained in Comparative Example 2;

[0032] Fig. 9 This is a scanning electron microscope photograph of the first graphite ring preform obtained in Comparative Example 3;

[0033] Fig.10 This is a metallographic photograph of the 6 series aluminum alloy bar blank obtained in Comparative Example 5. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0035] As described in the background technology, there is a problem in the prior art that the oil and gas lubrication effect of the equipment in which the graphite ring used for casting crystallizer is poor due to the poor performance of the graphite ring used for casting crystallizer, which leads to poor surface performance and mechanical properties of the 6 series aluminum alloy castings obtained by casting. In order to solve the above technical problems, the first aspect of the present invention provides a graphite ring for aluminum alloy casting crystallizer, which includes a graphite ring body, a sealing layer and a sealing ring. The graphite ring body has a top wall, an inner wall, an outer wall and a bottom wall. The sealing layer is arranged on the top wall and the bottom wall, and the sealing ring is arranged at the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall; by weight, the graphite ring body includes 5 to 10 parts of graphite powder, 2 to 3 parts of phenolic resin powder, 1 to 2 parts of modified phenolic resin and 1 to 2 parts of secondary carbon microbeads; the sealing layer and the sealing ring are both silicone polymers.

[0036] The present invention optimizes the graphite components of the graphite ring body, that is, adds a specific proportion of graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads, and combines the optimized sealing layer and sealing ring design to effectively improve the thermal conductivity and high temperature resistance of the graphite ring, and improve the permeability and thermal conductivity of the graphite ring. And because the average pore size in its internal microstructure increases, the average porosity increases, and the thermal conductivity is also significantly improved, so that it can conduct heat more significantly in the high temperature and high pressure aluminum alloy casting process, improve the stability of the oil-gas sliding casting process and the comprehensive quality of the resulting casting. At the same time, by combining the optimized sealing layer and sealing ring design, the problem of lubricating oil overflow and air leakage in the inner cavity of the crystallizer is solved, thereby eliminating the surface oil spots and scale defects of the ingot obtained by casting. The aluminum alloy casting crystallizer graphite ring prepared by the present invention is used for oil-gas sliding casting of aluminum alloy ingots, which can reduce casting defects, improve the surface quality and internal organization of castings, eliminate coarse crystals, significantly reduce the thickness of the segregation layer of the resulting ingot, eliminate surface cold shut defects, and significantly improve mechanical properties. Based on the above reasons, the present invention effectively improves production efficiency, is suitable for the production of high-precision and high-performance aluminum alloy materials, and has significant economic and social benefits.

[0037] In several preferred embodiments, the graphite ring body is a porous structure with a porosity of 15 Vol.% to 30 Vol.%; and the thermal conductivity of the graphite ring body is 110 W / (m·K) to 200 W / (m·K). The present invention optimizes the porous structure of the graphite ring body so that the obtained graphite ring has better air permeability and uniform thermal conductivity while maintaining high strength, and is suitable for casting processes that require good heat conduction and gas emission, and effectively avoids the generation of defects such as pores inside aluminum alloy castings.

[0038] In order to more significantly optimize the microstructure of the graphite ring, improve the uniformity of the internal organization, thereby optimize its thermal conductivity, reduce the segregation phenomenon inside the aluminum alloy casting during the casting process, and improve the mechanical properties and surface properties of the resulting ingot, the graphite powder is preferably flake graphite powder, and the flake graphite powder has a sheet diameter of 100 to 200 meshes. And / or, in order to optimize the thermal stability and wear resistance of the resulting graphite ring, the particle size of the secondary carbon microbeads is preferably 15 μm to 20 μm, so as to improve the reliability and safety during the casting process.

[0039] Among them, the modified phenolic resin is particularly preferred to be epoxy-modified phenolic resin, so as to improve the structural strength and high temperature resistance of the graphite ring, so that it can maintain good structural integrity and sealing under high temperature conditions of casting. In actual use, the epoxy-modified phenolic resin with the brand name SNE-625 produced by Hunan Saierwei New Materials is preferably used.

[0040] Furthermore, the outer wall of the graphite ring body is also independently provided with: an oil outlet groove; and Figure 4 As shown, the first annular groove 11 and the second annular groove 12 are arranged around the main body of the graphite ring, and the first annular groove 11 and the second annular groove 12 are arranged along the circumference of the main body of the graphite ring; preferably, starting from the bottom wall, the first annular groove 11 is located at 4 / 19~6 / 19 of the height of the outer wall, and the second annular groove 12 is located at 8 / 19~10 / 19 of the height of the outer wall; and / or, starting from the bottom wall, the oil outlet groove is located at 2 / 3~3 / 4 of the height of the outer wall. The above-mentioned graphite ring body structural design optimized by the inventors after a large number of experiments effectively improves the lubricity and thermal stress distribution of the resulting graphite ring, can better control the heat flow and lubrication during the casting process of aluminum alloy, and improves the surface quality and dimensional accuracy of the resulting casting.

[0041] In order to more effectively improve the mechanical stress distribution of the obtained graphite ring during the casting process, and optimize its structural stability and sealing when subjected to thermal stress, the wall thickness of the graphite ring for aluminum alloy casting crystallizer is preferably 5mm~8mm. In order to optimize the heat conduction path and lubrication effect of the graphite ring during the aluminum alloy casting process, improve the heat conduction, cooling and lubrication effects, and thus improve the surface quality and uniformity of the internal structure of the obtained aluminum alloy casting, it is more preferred that: the ratio of the depth to the width of the first annular groove is N1, the ratio of the depth to the width of the second annular groove is N2, N1 and N2 are each independently 1: (2~3), the depth of the first annular groove and the second annular groove are each independently 2.0mm~4.0mm; and / or, the specification of the oil outlet groove is Φ2mm~Φ4mm, and the depth is 2.0mm~2.5mm.

[0042] In several preferred embodiments, the thickness of the sealing layer is 0.05 mm to 0.15 mm; the thickness of the sealing ring is 0.03 mm to 0.05 mm. The design of the sealing layer and the sealing ring of the above dimensions enables the obtained graphite ring to fit more closely with the casting crystallizer, thereby more effectively preventing the leakage of the casting aluminum liquid and the overflow of the lubricating oil in the inner cavity of the crystallizer, and improving the yield rate and surface performance of the obtained casting.

[0043] The second aspect of the present invention provides a method for preparing the above-mentioned graphite ring for aluminum alloy casting crystallizer, comprising: step S1, preparing a graphite ring preform; step S1-1, batching: mixing graphite powder, phenolic resin powder, modified phenolic resin powder and secondary carbon microbeads to obtain a mixed powder; step S1-2, molding: the mixed powder is sequentially pressed and first cured to obtain a graphite ring blank; step S1-3, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-4, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-5, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-6, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-7, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-8, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-9, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-10, sintering: sintering the graphite blank to obtain a first graphite ring preform; step S1-11, sintering: mixing the graphite powder, phenolic resin powder, modified phenolic resin powder and secondary carbon microbeads to obtain a mixed powder; step S1-2 Step S2, machining the first graphite ring preform into a graphite ring body; step S3, coating the top wall and the bottom wall of the graphite ring body with a silicone sealant, obtaining a pre-sealing layer after a first pre-curing, coating the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall with a silicone sealant, obtaining a pre-sealing ring after a second pre-curing; and then obtaining a second graphite ring preform; step S4, the second graphite ring preform is subjected to a second curing to obtain a graphite ring for an aluminum alloy casting crystallizer.

[0044] With respect to the above-mentioned graphite ring for aluminum alloy casting crystallizer, the present invention provides a preparation method thereof accordingly. By precisely controlling the specific method steps and process sequence stages, a graphite ring with better microporous structure and better adaptability between the ring body and the sealing layer and the sealing ring is prepared. With high production consistency and reliability, a graphite ring for aluminum alloy casting crystallizer with better casting effect is obtained.

[0045] And, in practical applications, the mixing time in step S1-1 is preferably 2h~3h, so that the various components of the graphite ring body can be better mixed and dispersed, thereby improving the uniformity of the organizational structure and thermal conductivity of the obtained graphite ring body, thereby further optimizing the comprehensive performance of the aluminum alloy casting obtained by casting.

[0046] In order to improve the structural stability and dimensional accuracy of the obtained graphite ring body, it is preferred that in step S1-2, pressing is performed at 90°C to 110°C; the temperature of the first solidification is 140°C to 160°C, and the time is 20min to 30min. The above-mentioned pressing and solidification conditions can form a graphite ring body with better structural consistency and stability, and can also effectively inhibit the excessive pyrolysis of each component in the ring body during the molding process, thereby improving the yield rate of the obtained graphite ring for aluminum alloy casting crystallizer.

[0047] For the final sintering process of the graphite ring body, the sintering temperature in step S1-3 is preferably 2200°C~2800°C, and the time is 5h~9h, so as to further improve the structural stability of the obtained graphite ring body, optimize its performance in the casting process, and finally improve the comprehensive performance of the obtained casting. It is preferred that the sintering is carried out under the protection of an inert gas, and the inert gas is further preferably introduced at a pressure of 100MPa~300MPa, which can effectively inhibit the oxidation of the components in the graphite ring body at high temperature, improve its thermal stability and corrosion resistance, and thus improve its long-term service stability and reliability in the casting process.

[0048] In several typical embodiments, the inventors have preferred, through a large number of experiments, that in step S3, the first pre-curing time is 4h~24h, and / or the second pre-curing time is 12h~36h. The precise control of the above pre-curing stage more effectively makes the sealing layer and the sealing ring uniformly cured, improves its sealing performance, and further more effectively reduces the generation of various defects in the casting process, and improves the comprehensive performance of the obtained aluminum alloy casting. At the same time, it is further preferred that the temperature of the first pre-curing and the second pre-curing is independently 25±2℃.

[0049] In step S4, the second curing temperature is preferably 40°C~60°C, and the time is 12h~24h, which can further make the combination between the sealing ring, the sealing layer and the graphite ring body more stable, and the sealing system formed by the sealing ring and the sealing layer is more functional, thereby improving the structural stability and sealing of the graphite ring for aluminum alloy casting crystallizer, so as to show higher performance stability and longer service life during high-temperature casting, and also further improve the surface properties and mechanical properties of the resulting casting.

[0050] The third aspect of the present invention provides an oil-gas lubrication casting method for 6-series aluminum alloy billets, wherein the oil-gas lubrication casting equipment used in the oil-gas lubrication casting method includes an aluminum alloy casting crystallizer, and the aluminum alloy casting crystallizer uses the above-mentioned graphite ring for aluminum alloy casting crystallizer. The graphite ring for aluminum alloy casting crystallizer prepared by the present invention has higher thermal conductivity, structural stability and better sealing. The application of such graphite rings significantly improves the oil-gas lubrication casting effect of 6-series aluminum alloy billets, the oil-gas lubrication effect during the casting process is more stable, and the surface quality and uniformity of the internal structure of the resulting casting are also higher.

[0051] In several typical implementations, a graphite ring for an aluminum alloy casting crystallizer is formed into an interference fit with the inner wall of the aluminum alloy casting crystallizer, and then a 6 series aluminum alloy billet is cast under the conditions of pulse gas supply and pulse oil supply; and the casting speed is 30 mm / min~220 mm / min, the casting temperature is 670°C~720°C, and the cooling water flow rate is 2m 3 / h~20m 3 / h; and / or, the pressure of pulse air supply is 0.5MPa~3.0MPa, and the air supply time / interval time is 1:(3~10); and / or, the oil volume of pulse oil supply is 10mL / h~60mL / h, the pressure is 4MPa~8MPa, and the air supply time / interval time is 1:(3~10).

[0052] The above-mentioned preferred casting parameters, combined with the oil and gas supply parameters in the pulse air supply and oil supply technology, can be coordinated with the above-mentioned characteristics of the graphite ring for the aluminum alloy casting crystallizer, thereby comprehensively optimizing the heat conduction and lubrication effects in the casting process, and ultimately significantly improving the mechanical properties, surface properties, yield and production efficiency of the obtained aluminum alloy castings, and reducing their energy consumption and production costs.

[0053] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0054] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0055] Example 1

[0056] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0057] Step S1, preparing a graphite ring preform:

[0058] Step S1-1, ingredients: flake graphite powder with a flake size of 100 mesh, phenolic resin powder, modified phenolic resin SNE-625 (manufactured by Hunan Sailwei New Materials) and secondary carbon microbeads with a particle size of 20 μm (manufactured by Zibo Bomai Ceramic Materials Co., Ltd.) are put into a ball mill in batches at a mass percentage of 5:2:1:1 and mixed thoroughly for 2 hours to obtain a mixed powder.

[0059] Step S1-2, pressing and curing: Control the metal mold temperature at 90°C, add the mixed powder The powder is placed in a pressing mold and flattened; the pressing head applies pressure to press the powder into a dense layered unit; the powder is spread and pressed for multiple times; finally, the temperature is raised to 160°C and the pressure is maintained for 30 minutes to complete the first solidification, and then the mold is cooled and demolded to obtain a porous graphite ring blank.

[0060] Step S1-3, sintering: the obtained blank is placed in a hot air circulation sintering furnace for roasting, and an inert protective gas is charged at an input pressure of 300 MPa. The high temperature sintering system is strictly controlled, the roasting temperature is 2200°C, and the heat and pressure are kept for 9 hours. The blank is cooled to room temperature and taken out of the furnace, and finally a first graphite ring preform with high porosity is obtained, and its scanning electron microscope photo is shown in Figure 1 .

[0061] Step S2, preparing the graphite ring body:

[0062] The graphite ring preform obtained in step S1 is processed into a graphite ring body by machining, and the obtained graphite ring body has a ring structure with a thickness of 5 mm, a height of 68 mm, and an inner radius of 65 mm;

[0063] At the same time, surrounding the obtained graphite ring body, a first annular groove and a second annular groove with a depth of 2 mm and a width of 4 mm (depth: width = 1:2) are provided on the outer wall thereof, the first annular groove and the second annular groove are both arranged along the circumference of the graphite ring body, and starting from the bottom wall of the graphite ring, the first annular groove is located at 5 / 19 of the height of the outer wall, and the second annular groove is located at 9 / 19 of the height of the outer wall;

[0064] In addition, a lubricating oil outlet groove is arranged on the main body of the graphite ring, with a specification of Φ2mm, a depth of 2mm, and a height starting from the bottom wall and located at 2 / 3 of the height of the outer wall.

[0065] The schematic diagram of the structure of the obtained graphite ring body is shown in Figure 2 , its front view is shown in Figure 3 , the cross-sectional view along the A-A' direction is shown Figure 4 .

[0066] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747, which is manufactured by Juli (Dongguan) New Material Technology Co., Ltd., and is applied to the top wall and bottom wall of the graphite ring body respectively, and a pre-sealing layer with a thickness of 0.06 mm is obtained after a first pre-curing at room temperature for 4 hours; then, the same silicone high-temperature sealant is applied to the intersections of the top wall and the inner wall, and the bottom wall and the inner wall of the graphite ring body respectively, and a pre-sealing ring with a thickness of 0.03 mm is obtained after a second pre-curing at room temperature for 12 hours, and the coating of the pre-sealing ring is adapted to the two intersections.

[0067] Step S4, subjecting the graphite ring obtained in step S3 to a second curing at 40° C. for 12 hours to obtain a sealing layer and a sealing ring, and further obtaining a graphite ring for an aluminum alloy casting crystallizer.

[0068] An oil-gas sliding casting method for 6 series aluminum alloy billet:

[0069] During installation, the obtained graphite ring is fitted to the inner wall of the crystallizer, and the graphite ring and the crystallizer are fitted with interference fit.

[0070] Using 6061 aluminum as raw material (its specific components are shown in the table below), the rod blank is cast according to the specification of Φ120mm. During the casting process:

[0071] Casting process: casting speed is 220mm / min, casting temperature is 670℃, cooling water flow is 2m 3 / h.

[0072] Oil-gas lubricating casting pulse air supply parameters: pressure is 0.5MPa, air supply time / interval time is 1:10.

[0073] Oil-gas lubricating casting pulse oil supply parameters: oil pressure 4MPa, oil volume 10mL / h, oil supply time / interval time 1:10.

[0074] The metallographic photograph of the obtained 6 series aluminum alloy billet is shown in Figure 5 , where the segregation layer is shown; the metallographic structure diagram is shown in Figure 6 .

[0075] Table 1 Specific components of 6061 aluminum

[0076]

[0077] Example 2

[0078] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0079] The only difference between this embodiment and embodiment 1 is that the amounts of the components of the graphite ring in step S1-1 are different, specifically: the mass percentages of flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads are changed to 7:2:1:2.

[0080] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0081] Example 3

[0082] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0083] The only difference between this embodiment and embodiment 1 is that the amounts of the components of the graphite ring in step S1-1 are different, specifically: the mass percentage of flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads is changed to 10:3:2:1.

[0084] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0085] Example 4

[0086] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0087] The difference between this embodiment and embodiment 1 is that the preparation conditions of the first graphite ring preform in step S1 are different, specifically:

[0088] Step S1-1, ingredients: put flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads in batches according to a mass percentage of 5:2:1:1 into a ball mill and mix thoroughly for 2.5 hours to obtain a mixed powder.

[0089] Step S1-2, pressing and curing: Control the metal mold temperature at 100°C, add the mixed powder The powder is placed in a pressing mold and flattened; the pressing head applies pressure to press the powder into a dense layered unit; the powder is spread and pressed for multiple times; finally, the temperature is raised to 170°C and the pressure is maintained for 25 minutes to complete the first solidification, and then the mold is cooled and demolded to obtain a porous graphite ring blank.

[0090] Step S1-3, sintering: the obtained blank is placed in a hot air circulation sintering furnace for roasting, and an inert protective gas is filled in at an input pressure of 200 MPa. The high-temperature sintering system is strictly controlled, the roasting temperature is 2500°C, and the heat and pressure are kept for 7 hours. The blank is cooled to room temperature and taken out from the furnace to finally obtain a first graphite ring preform with high porosity.

[0091] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0092] Example 5

[0093] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0094] The difference between this embodiment and embodiment 1 is that the preparation conditions of the first graphite ring preform in step S1 are different, specifically:

[0095] Step S1-1, ingredients: put flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads in batches according to a mass percentage of 5:2:1:1 into a ball mill and mix thoroughly for 3.0 hours to obtain a mixed powder.

[0096] Step S1-2, pressing and curing: Control the metal mold temperature at 110°C, add the mixed powder The powder is placed in a pressing mold and flattened; the pressing head applies pressure to press the powder into a dense layered unit; the powder is spread and pressed for multiple times; finally, the temperature is raised to 180°C and the pressure is maintained for 20 minutes to complete the first solidification, and then the mold is cooled and demolded to obtain a porous graphite ring blank.

[0097] Step S1-3, sintering: the obtained blank is placed in a hot air circulation sintering furnace for roasting, and an inert protective gas is filled in at an input pressure of 100 MPa. The high-temperature sintering system is strictly controlled, the roasting temperature is 2800°C, and the heat and pressure are kept for sintering for 5 hours. The blank is cooled to room temperature and taken out from the furnace to finally obtain a first graphite ring preform with high porosity.

[0098] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0099] Example 6

[0100] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0101] The difference between this embodiment and embodiment 1 is that the main body structure of the graphite ring obtained by machining in step S2 is different, specifically:

[0102] The graphite ring preform obtained in step S1 is processed into a graphite ring body by machining, and the obtained graphite ring body has a ring structure with a thickness of 5 mm, a height of 68 mm, and an inner radius of 65 mm;

[0103] At the same time, surrounding the obtained graphite ring body, a first annular groove and a second annular groove with a depth of 3 mm and a width of 7.5 mm (depth: width = 2:5) are provided on the outer wall of the graphite ring body. The first annular groove and the second annular groove are both arranged along the circumference of the graphite ring body, and starting from the bottom wall of the graphite ring, the first annular groove is located at 5 / 19 of the height of the outer wall, and the second annular groove is located at 9 / 19 of the height of the outer wall;

[0104] In addition, a lubricating oil outlet groove is arranged on the main body of the graphite ring, with a specification of Φ3mm, a depth of 2mm, and a height starting from the bottom wall, located at 17 / 24 of the height of the outer wall.

[0105] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0106] Example 7

[0107] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0108] The difference between this embodiment and embodiment 1 is that the main body structure of the graphite ring obtained by machining in step S2 is different, specifically:

[0109] The graphite ring preform obtained in step S1 is processed into a graphite ring body by machining, and the obtained graphite ring body has a ring structure with a thickness of 5 mm, a height of 68 mm, and an inner radius of 65 mm;

[0110] At the same time, surrounding the obtained graphite ring body, a first annular groove and a second annular groove with a depth of 4 mm and a width of 12 mm (depth: width = 1:3) are provided on the outer wall thereof, the first annular groove and the second annular groove are both arranged along the circumference of the graphite ring body, and starting from the bottom wall of the graphite ring, the first annular groove is located at 5 / 19 of the height of the outer wall, and the second annular groove is located at 9 / 19 of the height of the outer wall;

[0111] In addition, a lubricating oil outlet groove is arranged on the main body of the graphite ring, with a specification of Φ4mm, a depth of 2mm, and a height starting from the bottom wall and located at 3 / 4 of the height of the outer wall.

[0112] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0113] Example 8

[0114] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0115] The difference between this embodiment and embodiment 1 is that step S3 is different from step S4. Specifically:

[0116] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747 and a manufacturer of Juli (Dongguan) New Material Technology Co., Ltd., and apply it on the top wall and bottom wall of the graphite ring body respectively, and obtain a pre-sealing layer with a thickness of 0.10 mm after a first pre-curing at room temperature for 14 hours; then use the same silicone high-temperature sealant to apply it on the intersections of the top wall and the inner wall, and the bottom wall and the inner wall of the graphite ring body respectively, and obtain a pre-sealing ring with a thickness of 0.04 mm after a second pre-curing at room temperature for 24 hours, and the coating of the pre-sealing ring is adapted to the two intersections.

[0117] Step S4, subjecting the graphite ring obtained in step S3 to a second curing at 50° C. for 16 hours to obtain a sealing layer and a sealing ring, and further obtaining a graphite ring for an aluminum alloy casting crystallizer.

[0118] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0119] Example 9

[0120] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0121] The difference between this embodiment and embodiment 1 is that step S3 is different from step S4. Specifically:

[0122] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747 and a manufacturer of Juli (Dongguan) New Material Technology Co., Ltd., and apply it on the top wall and bottom wall of the graphite ring body respectively, and obtain a pre-sealing layer with a thickness of 0.14 mm after a first pre-curing at room temperature for 24 hours; then use the same silicone high-temperature sealant to apply it on the intersections of the top wall and the inner wall, and the bottom wall and the inner wall of the graphite ring body respectively, and obtain a pre-sealing ring with a thickness of 0.05 mm after a second pre-curing at room temperature for 36 hours, and the coating of the pre-sealing ring is adapted to the two intersections.

[0123] Step S4, subjecting the graphite ring obtained in step S3 to a second curing at 60° C. for 24 hours to obtain a sealing layer and a sealing ring, and further obtaining a graphite ring for an aluminum alloy casting crystallizer.

[0124] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0125] Example 10

[0126] A method for preparing a graphite ring for an aluminum alloy casting crystallizer: proceed according to the conditions in Example 1.

[0127] An oil-gas sliding casting method for 6 series aluminum alloy billet:

[0128] During installation, the obtained graphite ring is fitted to the inner wall of the crystallizer, and the graphite ring and the crystallizer are fitted with interference fit.

[0129] Using 6061 aluminum as raw material (its specific components are as shown in the above table: Specific components of 6061 aluminum), casting is performed according to the specification of Φ240mm to obtain a rod blank. During the casting process:

[0130] Casting process: casting speed is 120mm / min, casting temperature is 690℃, cooling water flow is 10m 3 / h.

[0131] Oil-gas lubricating casting pulse air supply parameters: pressure is 1.3MPa, air supply time / interval time is 1:6.

[0132] Oil-gas lubricating casting pulse oil supply parameters: oil pressure 6MPa, oil volume 35mL / h, oil supply time / interval time 1:6.

[0133] Embodiment 11

[0134] A method for preparing a graphite ring for an aluminum alloy casting crystallizer: proceed according to the conditions in Example 1.

[0135] An oil-gas sliding casting method for 6 series aluminum alloy billet:

[0136] During installation, the obtained graphite ring is fitted to the inner wall of the crystallizer, and the graphite ring and the crystallizer are fitted with interference fit.

[0137] Using 6061 aluminum as raw material (its specific components are as shown in the above table: Specific components of 6061 aluminum), casting is performed according to the specification of Φ600mm to obtain a rod blank. During the casting process:

[0138] Casting process: casting speed is 30mm / min, casting temperature is 720℃, cooling water flow is 20m 3 / h.

[0139] Oil-gas lubricating casting pulse air supply parameters: pressure is 3.0MPa, air supply time / interval time is 1:3.

[0140] Oil-gas lubricating casting pulse oil supply parameters: oil pressure 8MPa, oil volume 60mL / h, oil supply time / interval time 1:3.

[0141] Example 12

[0142] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0143] The difference between this embodiment and embodiment 1 is that the preparation conditions of the first graphite ring preform in step S1 are different, specifically:

[0144] Step S1-1, ingredients: put flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads in batches according to a mass percentage of 5:2:1:1 into a ball mill and mix thoroughly for 1.5 hours to obtain a mixed powder.

[0145] Step S1-2, pressing and curing: Control the metal mold temperature at 60°C, add the mixed powder The powder is placed in a pressing mold and flattened; the pressing head applies pressure to press the powder into a dense layered unit; the powder is spread and pressed for multiple times; finally, the temperature is raised to 140°C, the pressure is maintained for 15 minutes to complete the first solidification, and then the mold is cooled and demolded to obtain a porous graphite ring blank.

[0146] Step S1-3, sintering: the obtained blank is placed in a hot air circulation sintering furnace for roasting, and an inert protective gas is filled in at an input pressure of 80 MPa. The high-temperature sintering system is strictly controlled, the roasting temperature is 1800°C, and the heat and pressure are kept for sintering for 2 hours. The blank is cooled to room temperature and taken out from the furnace to finally obtain a first graphite ring preform with high porosity.

[0147] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0148] Embodiment 13

[0149] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0150] The difference between this embodiment and embodiment 1 is that the preparation conditions of the first graphite ring preform in step S1 are different, specifically:

[0151] Step S1-1, ingredients: put flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads in batches according to a mass percentage of 5:2:1:1 into a ball mill and mix thoroughly for 3.5 hours to obtain a mixed powder.

[0152] Step S1-2, pressing and curing: Control the metal mold temperature at 140°C, add the mixed powder The powder is placed in a pressing mold and flattened; the pressing head applies pressure to press the powder into a dense layered unit; the powder is spread and pressed for multiple times; finally, the temperature is raised to 180°C and the pressure is maintained for 40 minutes to complete the first solidification, and then the mold is cooled and demolded to obtain a porous graphite ring blank.

[0153] Step S1-3, sintering: the obtained blank is placed in a hot air circulation sintering furnace for roasting, and an inert protective gas is filled in at an input pressure of 350 MPa. The high-temperature sintering system is strictly controlled, the roasting temperature is 3000°C, and the heat and pressure are kept for 10 hours. The blank is cooled to room temperature and taken out from the furnace to finally obtain a first graphite ring preform with high porosity.

[0154] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0155] Embodiment 14

[0156] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0157] The difference between this embodiment and embodiment 1 is that the main body structure of the graphite ring obtained by machining in step S2 is different, specifically:

[0158] The graphite ring preform obtained in step S1 is processed into a graphite ring body by machining, and the obtained graphite ring body has a ring structure with a thickness of 5 mm, a height of 68 mm, and an inner radius of 65 mm;

[0159] At the same time, surrounding the obtained graphite ring body, only the outer wall thereof is provided with a first annular groove with a depth of 1 mm and a width of 8 mm (depth: width = 1:4), the first annular groove is arranged along the circumference of the graphite ring body, and starting from the bottom wall of the graphite ring, the first annular groove is located at 5 / 19 of the height of the outer wall;

[0160] In addition, a lubricating oil outlet groove is arranged on the main body of the graphite ring, with a specification of Φ1mm, a depth of 2mm, and a height starting from the bottom wall and located at 1 / 3 of the height of the outer wall.

[0161] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0162] Embodiment 15

[0163] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0164] The difference between this embodiment and embodiment 1 is that the main body structure of the graphite ring obtained by machining in step S2 is different, specifically:

[0165] The graphite ring preform obtained in step S1 is processed into a graphite ring body by machining, and the obtained graphite ring body has a ring structure with a thickness of 5 mm, a height of 68 mm, and an inner radius of 65 mm;

[0166] At the same time, surrounding the obtained graphite ring body, only the outer wall thereof is provided with a first annular groove with a depth of 5 mm and a width of 2.5 mm (depth: width = 2:1), the first annular groove is arranged along the circumference of the graphite ring body, and starting from the bottom wall of the graphite ring, the first annular groove is located at 5 / 19 of the height of the outer wall;

[0167] In addition, a lubricating oil outlet groove is arranged on the main body of the graphite ring, with a specification of Φ5mm, a depth of 2mm, and a height starting from the bottom wall, located at 7 / 8 of the height of the outer wall.

[0168] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0169] Example 16

[0170] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0171] The only difference between this embodiment and embodiment 1 is that the main body structure of the graphite ring obtained by machining in step S2 is different, specifically: no annular groove is provided.

[0172] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0173] Embodiment 17

[0174] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0175] The difference between this embodiment and embodiment 1 is that step S4 is different, specifically:

[0176] Step S4, subjecting the graphite ring obtained in step S3 to a second curing at 30° C. for 36 hours to obtain a sealing layer and a sealing ring, and further obtaining a graphite ring for an aluminum alloy casting crystallizer.

[0177] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0178] Embodiment 18

[0179] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0180] The difference between this embodiment and embodiment 1 is that step S4 is different, specifically:

[0181] Step S4, subjecting the graphite ring obtained in step S3 to a second curing at 70° C. for 12 hours to obtain a sealing layer and a sealing ring, and further obtaining a graphite ring for an aluminum alloy casting crystallizer.

[0182] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0183] Comparative Example 1

[0184] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0185] The only difference between this embodiment and embodiment 1 is that the amounts of the components of the graphite ring in step S1-1 are different, specifically: no modified phenolic resin and secondary carbon microbeads are added.

[0186] The scanning electron microscope photo of the first graphite ring preform obtained is shown in Figure 7 .

[0187] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0188] Comparative Example 2

[0189] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0190] The only difference between this embodiment and embodiment 1 is that the amounts of the components of the graphite ring in step S1-1 are different, specifically: no secondary carbon microbeads are added.

[0191] The scanning electron microscope photo of the first graphite ring preform obtained is shown in Figure 8 .

[0192] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0193] Comparative Example 3

[0194] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0195] The only difference between this embodiment and embodiment 1 is that the amounts of the components of the graphite ring in step S1-1 are different, specifically: the mass percentage of flake graphite powder, phenolic resin powder, modified phenolic resin and secondary carbon microbeads is changed to 15:2:1:1.

[0196] The scanning electron microscope photo of the first graphite ring preform obtained is shown in Fig. 9 .

[0197] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0198] Comparative Example 4

[0199] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0200] The only difference between this embodiment and embodiment 1 is that 107 silicone rubber, that is, room temperature sealant, is used in step S3 to form the sealing layer and the sealing ring instead of organic silicon high temperature sealant.

[0201] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0202] Comparative Example 5

[0203] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0204] The difference between this embodiment and embodiment 1 is that step S3 is different, specifically:

[0205] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747 and a manufacturer of Juli (Dongguan) New Material Technology Co., Ltd., and apply it on the top and bottom walls of the graphite ring body respectively. After the first pre-curing at room temperature for 1 hour, a pre-sealing layer with a thickness of 0.1 mm is obtained; at the same time, no sealing ring is formed.

[0206] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0207] The metallographic photograph of the obtained 6 series aluminum alloy billet is shown in Fig.10 , where the segregation layer is shown.

[0208] Comparative Example 6

[0209] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0210] The difference between this embodiment and embodiment 1 is that step S3 is different, specifically:

[0211] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747 and a manufacturer of Juli (Dongguan) New Material Technology Co., Ltd., and apply it on the top and bottom walls of the graphite ring body respectively. After the first pre-curing at room temperature for 2 hours, a pre-sealing layer with a thickness of 0.15 mm is obtained; at the same time, no sealing ring is formed.

[0212] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0213] Comparative Example 7

[0214] A method for preparing a graphite ring for an aluminum alloy casting crystallizer:

[0215] The difference between this embodiment and embodiment 1 is that step S3 is different, specifically:

[0216] Step S3, setting a sealing layer and a sealing ring: select a silicone high-temperature sealant with a model number of JL-747 and a manufacturer of Juli (Dongguan) New Material Technology Co., Ltd., and apply it on the top and bottom walls of the graphite ring body respectively. After the first pre-curing at room temperature for 3 hours, a pre-sealing layer with a thickness of 0.2 mm is obtained; at the same time, no sealing ring is formed.

[0217] An oil-gas sliding casting method for a 6-series aluminum alloy billet is carried out according to the conditions in Example 1.

[0218] Test Method

[0219] Porosity of graphite ring body: tested in accordance with GB / T 3365-2008.

[0220] Thermal conductivity of graphite rings for aluminum alloy casting crystallizers: tested in accordance with GB / T 8722-2008.

[0221] On-site working condition observation during oil-gas lubricant casting: ① Whether the graphite ring is leaking oil; ② Whether the graphite ring is leaking air; ③ The operating stability of the oil-gas lubricant casting equipment.

[0222] The above test results are shown in Table 2.

[0223] Segregation layer thickness of 6 series aluminum alloy bar billet obtained by casting: the test method is GB / T 3246.1-2024.

[0224] The internal average grain size of the 6 series aluminum alloy bar billet obtained by casting: the macrostructure test is carried out in accordance with GB / T 3246.1-2024.

[0225] The tensile strength and elongation of the 6 series aluminum alloy rod billet obtained by casting are tested in accordance with GB / T228.1-2021.

[0226] Preparation and performance testing of end products: The 6 series aluminum alloy rods obtained in the above embodiments and comparative examples were subjected to pre-forging and final forging at 480°C, and solution aging treatment at 535°C×190min+180°C×8 h to obtain a 22.5-inch aluminum alloy forged wheel hub sample. The surface mottling was observed, and the tensile strength and elongation were tested in accordance with GB / T228.1-2021.

[0227] The test results are shown in Table 3. Meanwhile, for the wheel hub sample finally obtained in the embodiment of the present invention, the grains inside the product are small and there is no mottle on the surface; while the wheel hub sample obtained in the comparative example has coarse grains inside the product and there are common mottles on the surface.

[0228] Table 2

[0229]

[0230] Table 3

[0231]

[0232] From the above description, it can be seen that the above-mentioned embodiment of the present invention realizes the preparation of graphite rings for aluminum alloy casting crystallizers with high porosity and high thermal conductivity. The obtained graphite rings are fitted with the inner wall of the aluminum alloy casting crystallizer to form an interference fit, and then the 6 series aluminum alloy bar billet is cast under the conditions of pulse gas supply and pulse oil supply. The segregation phenomenon of the obtained 6 series aluminum alloy bar billet is reduced, the internal structure is optimized, the grains are fine, and the comprehensive performance is improved. After the obtained bar billet is further processed into a terminal product, the obtained aluminum alloy product exhibits excellent mechanical properties and surface properties.

[0233] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0234] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A graphite ring for aluminum alloy casting crystallizer, characterized in that: The graphite ring for aluminum alloy casting crystallizer comprises a graphite ring body, a sealing layer and a sealing ring, wherein the graphite ring body has a top wall, an inner wall, an outer wall and a bottom wall. The sealing layer is arranged on the top wall and the bottom wall, and the sealing ring is arranged at the intersection of the top wall and the inner wall and at the intersection of the bottom wall and the inner wall; The graphite ring body includes 5 to 10 parts of graphite powder, 2 to 3 parts of phenolic resin powder, 1 to 2 parts of modified phenolic resin and 1 to 2 parts of secondary carbon microbeads in parts by weight; The sealing layer and the sealing ring are both made of silicone polymer.

2. The graphite ring for aluminum alloy casting crystallizer according to claim 1, characterized in that: The graphite ring body is a porous structure with a porosity of 15 Vol.% to 30 Vol.%; the thermal conductivity of the graphite ring body is 110 W / (m·K) to 200 W / (m·K).

3. The graphite ring for aluminum alloy casting crystallizer according to claim 1, characterized in that: The graphite powder is flake graphite powder, and the flake graphite powder has a sheet diameter of 100 mesh to 200 mesh; and / or, The particle size of the secondary carbon microbeads is 18 μm to 20 μm; and / or, The modified phenolic resin is epoxy modified phenolic resin.

4. The graphite ring for aluminum alloy casting crystallizer according to claim 3, characterized in that: The outer wall of the graphite ring body is also independently provided with: an oil outlet tank; and, A first annular groove and a second annular groove are arranged around the main body of the graphite ring, and the first annular groove and the second annular groove are arranged along the circumference of the main body of the graphite ring; Starting from the bottom wall, the first annular groove is located at 4 / 19 to 6 / 19 of the height of the outer wall, and the second annular groove is located at 8 / 19 to 10 / 19 of the height of the outer wall; and / or, starting from the bottom wall, the oil outlet groove is located at 2 / 3 to 3 / 4 of the height of the outer wall; The ratio of the depth to the width of the first annular groove is N1, and the ratio of the depth to the width of the second annular groove is N2. The N1 and the N2 are each independently 1:(2-3). The depths of the first annular groove and the second annular groove are each independently 2.0 mm to 4.0 mm. And / or, the oil outlet groove has a specification of Φ2mm~Φ4mm and a depth of 2.0mm~2.5mm.

5. The graphite ring for aluminum alloy casting crystallizer according to claim 4, characterized in that: The thickness of the sealing layer is 0.05 mm to 0.15 mm; The thickness of the sealing ring is 0.03mm~0.05mm.

6. A method for preparing a graphite ring for an aluminum alloy casting crystallizer according to any one of claims 1 to 5, characterized in that: include: Step S1, preparing a graphite ring preform; Step S1-1, mixing ingredients: mixing graphite powder, phenolic resin powder, modified phenolic resin powder and secondary carbon microbeads to obtain a mixed powder; Step S1-2, molding: the mixed powder is pressed and first cured in sequence to obtain a graphite ring blank; Step S1-3, sintering: sintering the graphite ring blank to obtain a first graphite ring preform; Step S2, machining the first graphite ring preform into the graphite ring portion body; Step S3, applying silicone sealant on the top wall and the bottom wall of the graphite ring body, obtaining a pre-sealing layer after a first pre-curing, applying silicone sealant on the intersection of the top wall and the inner wall and the intersection of the bottom wall and the inner wall, obtaining a pre-sealing ring after a second pre-curing; and then obtaining a second graphite ring preform; Step S4, the second graphite ring preform is subjected to a second solidification to obtain the graphite ring for the aluminum alloy casting crystallizer.

7. The method for preparing a graphite ring for an aluminum alloy casting crystallizer according to claim 6, characterized in that: In step S1-2, The pressing is carried out at 90°C to 110°C; The first curing is performed at a temperature of 140° C. to 160° C. and for a time of 20 min to 30 min.

8. The method for preparing a graphite ring for an aluminum alloy casting crystallizer according to claim 7, characterized in that: In step S1-3, The sintering temperature is 2200° C. to 2800° C. and the sintering time is 5 h to 9 h; and / or, The sintering is carried out under the protection of an inert gas, and the pressure of the inert gas is 100 MPa to 300 MPa.

9. The method for preparing a graphite ring for an aluminum alloy casting crystallizer according to claim 8, characterized in that: In step S3, The first pre-curing time is 4h~24h, and / or the second pre-curing time is 12h~36h; The temperatures of the first pre-curing and the second pre-curing are each independently 25±2°C.

10. The method for preparing a graphite ring for an aluminum alloy casting crystallizer according to claim 9, characterized in that: In step S4, the temperature of the second curing is 40°C to 60°C, and the time is 12h to 24h.

11. An oil-gas sliding casting method for 6 series aluminum alloy billet, characterized in that: The oil-gas sliding casting equipment used in the oil-gas sliding casting method includes an aluminum alloy casting crystallizer, and the aluminum alloy casting crystallizer uses the graphite ring for the aluminum alloy casting crystallizer according to any one of claims 1 to 5.

12. The oil-gas sliding casting method for 6 series aluminum alloy billet according to claim 11, characterized in that: The graphite ring of the aluminum alloy casting crystallizer is formed into an interference fit with the inner wall of the aluminum alloy casting crystallizer, and then the 6 series aluminum alloy bar billet is cast under the conditions of pulse air supply and pulse oil supply; and, The casting speed of the casting is 30mm / min~220mm / min, the casting temperature is 670℃~720℃, and the cooling water flow rate is 2m 3 / h~20m 3 / h; and / or, The pressure of the pulse gas supply is 0.5MPa~3.0MPa, and the gas supply time / interval time is 1:(3~10); and / or, The oil volume of the pulse oil supply is 10mL / h~60mL / h, the pressure is 4MPa~8MPa, and the gas supply time / interval time is 1:(3~10).

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