Casting process of ball-milled casting cast through wire feeding spheroidizing and application of casting process

Abstract

The invention discloses a casting process of a ball-milled casting cast by wire feeding spheroidizing and application of the casting process, solves the problem that molten iron is inoculated by adopting a granular inoculant in the prior art, and has the beneficial effects that the reaction rate is increased, and the stability of the inoculation effect is improved. According to the specific scheme, the casting technology of the ball-milling casting formed through wire feeding spheroidizing casting comprises the steps that waste steel and recirculated iron are added into a furnace, then pig iron is added, and molten iron is formed through smelting; the components of the molten iron are finely adjusted, so that the molten iron comprises, by mass, 3.7%-3.9% of carbon, 1.0%-1.5% of silicon, 0.1%-0.3% of manganese, less than or equal to 0.06% of phosphorus and less than or equal to 0.05% of sulfur; the temperature of the molten iron is increased to 1520-1530 DEG C, heat preservation is conducted, and standing is conducted for set time; pretreatment is conducted on the molten iron, specifically, a pretreatment agent is added to an iron outlet groove before the molten iron is discharged, the mass of the pretreatment agent is 0.25%-0.35% of the mass of the discharged iron, silicon is brought in in the pretreatment process, and the mass of the silicon is 0.15%-0.2% of the mass of the discharged iron; and the spheroidizing line is added into a spheroidizing chamber of the spheroidizing reaction ladle.

Description

Technical Field

[0001] This invention relates to the field of wind turbine bearing cage technology, and in particular to a casting process for ball mill castings produced by wire feeding spheroidization casting and its application. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Wind turbine bearings are key components of wind turbine generator sets, mainly used in systems such as main shafts, gearboxes, and yaw and pitch control. They bear the weight of the blades and hub and transmit power. Wind turbine bearings contain bearing cages to isolate and guide the rolling elements. The bearing cages must withstand centrifugal force and frictional heat. The wind power environment is characterized by high humidity, large temperature differences, and frequent impact loads. Wind turbine bearing cages need to be corrosion-resistant, fatigue-resistant, and thermally stable. Most wind turbine bearing cages are formed using casting processes, but currently, most wind turbine bearing cages are made using die casting methods.

[0004] In the casting process of wind turbine bearing cages, inoculants are often used for inoculation. However, granular inoculants are usually chosen here. When granular inoculants are sprinkled in the spheroidizing ladle, uneven distribution can easily occur. In some areas, the inoculant accumulates, leading to localized over-inoculation, while in other areas, the inoculant content is insufficient, resulting in poor inoculation. This not only affects the graphite morphology and distribution of the casting but may also cause significant fluctuations in the mechanical properties of the casting. At the same time, the contact area between granular inoculants and molten iron is relatively limited, resulting in insufficient reaction and easy waste of inoculant, increasing production costs.

[0005] Furthermore, in the casting process of wind turbine bearing cages that are larger and thicker, it is necessary to control the composition and temperature of the molten iron to ensure the smooth forming of the wind turbine bearing cage. This is definitely different from the control of the composition and temperature of molten iron for thin-walled and smaller-sized bearings. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a casting process for ball mill castings by wire feeding spheroidization casting, which improves the stability of the inoculation effect and ensures the performance of the castings in all aspects.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: A casting process for ball mill castings using wire-feeding spheroidizing casting includes the following: Scrap steel and recycled iron are added to the furnace, followed by pig iron, and then smelted to form molten iron. The composition of the molten iron is finely adjusted to include carbon, silicon, manganese, phosphorus, and sulfur, with the following mass percentages: 3.7%-3.9%, 1.0%-1.5%, 0.1%-0.3%, ≤0.06%, and ≤0.05%, respectively. Raise the temperature of the molten iron to 1520℃-1530℃, keep it at that temperature and let it stand for a set time; Spheroidization and incubation treatment: When spheroidizing lines are added to molten iron, they introduce silicon and magnesium during the process. Adding the inoculation line to the molten iron introduces silicon during the process. Iron pretreatment: Before tapping the molten iron, a pretreatment agent is added at the tapping trough. The mass of the pretreatment agent is 0.25%-0.35% of the tapped iron mass. Silicon is introduced during the pretreatment process. Inoculation treatment: Add a primary inoculant to the spheroidizing chamber of the spheroidizing reaction package. The mass of the primary inoculant is 0.5%-0.7% of the iron output mass, and it also introduces silicon. The casting temperature is controlled at 1400℃-1370℃. A secondary inoculant is added during casting, which is 0.09%-0.15% of the iron mass and carries in silicon. Stop pouring after the set time.

[0008] The casting process for ball mill castings using wire feeding spheroidization casting as described above involves adding 22-28 meters of spheroidizing wire at a feeding speed of 28-33 meters per minute.

[0009] The casting process for a ball mill casting using wire feeding spheroidization casting as described above, wherein the composition of the spheroidization line includes silicon, calcium, magnesium, aluminum, rhenium, and magnesium oxide, with the mass percentages of silicon, calcium, magnesium, aluminum, rare earth elements, and magnesium oxide being 40%-50%, 2%-3.5%, 23%-30%, 0.5%-1.2%, 1.8%-3%, and 0.8%-2%, respectively.

[0010] The casting process for ball mill casting by wire feeding spheroidization as described above, wherein the inoculation line is a SiBaCa inoculation line, the amount of inoculation line added is 22 m / ton to 28 m / ton, and the wire feeding speed is 28 m / min to 33 m / min; The incubation line is composed of silicon, calcium, aluminum and barium, with the mass percentages of silicon, calcium, aluminum and barium being 65%-75%, 1%-3%, 0.8%-1.4% and 2.5%-3.8%, respectively.

[0011] In the above-described casting process for ball mill casting using wire feeding spheroidization casting, the primary inoculant is SiBaCa inoculant, and the secondary inoculant is Y-SiBi inoculant.

[0012] In the above-described casting process for ball mill casting using wire feeding ball mill casting, the particle size of the pretreatment agent is 0.2mm-1mm, the particle size of the primary inoculant is 3mm-8mm, and the particle size of the secondary inoculant is 0.2mm-0.7mm. The particle size of the spheroidizing lines is 220g / m-250g / m, and the particle size of the inoculation lines is 255g / m-285g / m.

[0013] The casting process for a ball mill casting using wire feeding spheroidizing casting, as described above, involves molten iron in the spheroidizing chamber after inoculation and spheroidizing treatment. The molten iron composition includes carbon, silicon, manganese, phosphorus, sulfur, magnesium, and rare earth elements, with the following mass percentages: 3.4%-3.8%, 2.6%-2.9%, 0.15%-0.2%, ≤0.06%, ≤0.02%, 0.04%-0.06%, and 0.02%-0.04%, respectively.

[0014] The casting process for ball mill castings using wire feeding spheroidization casting as described above, wherein the spheroidization line is a silicon-magnesium rare earth alloy Mg8RE3.

[0015] In the casting process of the ball mill casting by wire feeding spheroidization casting as described above, the ratio of the height to the diameter of the spheroidization reaction chamber is 1.5-2.0.

[0016] Secondly, the present invention also provides an application of the casting process of ball mill casting by wire feeding spheroidizing casting, which is applied to the casting of wind turbine bearing frames. When casting the wind turbine bearing frame, 75Si iron and silicon-barium alloy are used instead of the inoculation line for composite inoculation. The mass percentages of silicon, barium, aluminum and calcium in the 75Si iron and silicon-barium alloy are 60%-68%, 4%-6%, 1.0%-2.0% and 0.8%-2.2%, respectively.

[0017] The beneficial effects of the present invention are as follows: 1) In this invention, during the inoculation and spheroidization processes, spheroidization is performed first, and then an inoculation line is evenly covered on the spheroidization line. The inoculation line replaces the existing inoculant for the first inoculation. The inoculation line has a filamentous structure, which can ensure uniform mixing and rapid reaction with the molten iron, promote the spheroidization and stabilization of the molten iron, significantly reduce the supercooling of the molten iron, reduce the formation of white iron structure, and improve the morphology and distribution of graphite, further enhancing the mechanical properties of the casting. Compared with the pouring inoculation method, the wire feeding inoculation process avoids the problem of insufficient or declining inoculation caused by the inoculant floating on the surface of the molten iron and uneven distribution, making the inoculation effect more stable and lasting, thereby ensuring that the performance of each part of the casting is uniform.

[0018] By precisely controlling the content range of key elements such as carbon, silicon, manganese, phosphorus, and sulfur in molten iron, and controlling the content and control of each component in molten iron, and through the synergistic effect of molten iron pretreatment, spheroidizing treatment, and multiple inoculation treatments, the spheroidizing reaction is stabilized and controllable, effectively improving the spheroidization rate and graphite morphology of ball mill castings, thereby improving the mechanical properties of the castings, especially their impact toughness and wear resistance, to meet the usage requirements of wind turbine bearing cages.

[0019] 2) In this invention, the molten iron is pretreated. The pretreatment agent provides the molten iron with a preliminary silicon supplement, improving its fluidity and oxidation resistance. Barium improves product quality by purifying the molten iron and promoting graphitization. The spheroidizing line contains magnesium, rare earth elements, and other elements at a set mass percentage. Under the precise control of the wire feeding process, these elements can react uniformly with the molten iron, avoiding problems such as excessively rapid magnesium vapor escape or incomplete reaction that may occur in traditional spheroidizing methods. This ensures the stability of the spheroidizing effect. Moreover, the addition of magnesium oxide in the spheroidizing line, which has a greater affinity for sulfur in the molten iron than iron, can effectively reduce the sulfur content in the molten iron, creating favorable conditions for subsequent spheroidizing treatment. The composite inoculation system of SiBaCa inoculation line and Y-SiBi inoculator, as well as the in-flow inoculation process, can refine graphite grains, reduce graphite floating and segregation, and further improve the uniformity and density of the casting structure.

[0020] 3) In this invention, the first inoculation is carried out through an inoculation line, and a primary inoculant is added to the spheroidizing reaction vessel. During the flow of molten iron, a secondary inoculant is added along with the flow, forming a composite inoculation system. That is, wire feeding inoculation provides efficient and uniform basic inoculation in the early stage, while in-flow inoculation provides precise and supplementary inoculation in the later stage. This maximizes the inoculation effect throughout the casting process, significantly improves the comprehensive mechanical properties and dimensional stability of the ball mill castings, and extends the service life of the castings.

[0021] 4) In this invention, silicon is introduced during the inoculation and spheroidization processes to ensure that the components in the molten iron meet the set requirements after inoculation and spheroidization. Through the synergistic effect and precise proportion of these elements, combined with the dual strengthening of wire feeding inoculation and in-flow inoculation, the excellent comprehensive mechanical properties of ball mill castings, such as bearing cages, are ensured, such as high strength, high toughness and good wear resistance. This lays a solid foundation for the subsequent processing of ball mill castings and their application in related fields. Detailed Implementation

[0022] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, existing technologies using granular inoculants to inoculate molten iron are prone to problems such as insufficient reaction. In order to solve the above-mentioned technical problems, this invention proposes a casting process for ball mill castings using wire-feed spheroidizing casting.

[0024] Example 1 In a typical embodiment of the present invention, a casting process for ball mill castings using wire-feeding spheroidizing casting includes the following: Scrap steel and recycled iron are added to the furnace, followed by pig iron, and then smelted to form molten iron. The composition of the molten iron is finely adjusted to include carbon, silicon, manganese, phosphorus, and sulfur, with the following mass percentages: 3.7%-3.9%, 1.0%-1.5%, 0.1%-0.3%, ≤0.06%, and ≤0.05%, respectively. Raise the temperature of the molten iron to 1520℃-1530℃, keep it at that temperature and let it stand for a set time; Scrap steel and recycled iron are added to the furnace, followed by pig iron, and then smelted to form molten iron. The composition of the molten iron is finely adjusted to include carbon, silicon, manganese, phosphorus, and sulfur, with the following mass percentages: 3.7%-3.9%, 1.0%-1.5%, 0.1%-0.3%, ≤0.06%, and ≤0.05%, respectively. Raise the temperature of the molten iron to 1520℃-1530℃, keep it at that temperature and let it stand for a set time; Spheroidization and incubation treatment: Adding spheroidizing wire to molten iron introduces silicon and magnesium during the process. Since spheroidizing wire contains silicon and magnesium, the addition of silicon and magnesium is ensured during the process, thus adjusting the silicon and magnesium content in the molten iron. Add the inoculation line to the molten iron and evenly cover the spheroidizing line. Because the inoculation line contains silicon, and the silicon content in the inoculation line is relatively high, it further adjusts the silicon content in the molten iron and plays a role in inoculating and refining the grains. Iron pretreatment: Before tapping the molten iron, a pretreatment agent is added at the tapping trough. The mass of the pretreatment agent is 0.25%-0.35% (specifically 0.3%) of the tapped iron mass. The pretreatment agent contains silicon, which can introduce silicon and barium elements during the pretreatment process, providing initial silicon element supplementation to the molten iron, improving the fluidity and oxidation resistance of the molten iron. The barium element improves product quality by purifying the molten iron and promoting graphitization. Inoculation treatment: Add a primary inoculant to the spheroidizing chamber of the spheroidizing reaction package. The mass of the primary inoculant is 0.5%-0.7% (specifically 0.6%) of the iron output mass, and it also introduces silicon. The mass of silicon can be determined by determining the content of the inoculant. The casting temperature is controlled at 1400℃-1370℃. A secondary inoculant is added during casting, which is 0.09%-0.15% (specifically 0.1%) of the iron mass. It also introduces silicon. The quality of silicon can be determined by determining the content of the secondary inoculant. Stop pouring after the set pouring time (less than or equal to 10 minutes).

[0025] It needs to be explained that silicon and magnesium work together in the spheroidizing line. While magnesium plays a spheroidizing role, silicon further participates in adjusting the composition of the molten iron. The high silicon content in the inoculation line mainly plays the role of inoculating and refining the grains. The silicon in the pretreatment agent can initially adjust the silicon content of the molten iron, creating suitable conditions for the subsequent spheroidizing reaction. The subsequent inoculation treatment works synergistically to ensure that the molten iron obtains the ideal chemical composition and microstructure after spheroidizing treatment. Controlling the temperature of molten iron during casting: The temperature of molten iron is a very important factor affecting the quality of ductile iron. Referring to Table 1, for cast ductile iron, the temperature is generally controlled at 1450°C. o C-1500 o C, the lowest is 1420 o C. If the temperature of the molten iron is too low, it will lead to poor spheroidization; if the temperature of the molten iron is too high, the magnesium will be severely burned off. At the same time, if the temperature of the molten iron is too low, the casting is prone to defects such as slag inclusions, shrinkage cavities, and subcutaneous porosity.

[0026] Table 1 Requirements for molten iron temperature control

[0027] It should be explained that the raw materials include scrap steel and recycled iron. Scrap steel is controlled according to existing raw material acceptance standards, while recycled iron refers to iron waste containing alloying elements generated during industrial production.

[0028] Among these measures, different grades of recycled iron are classified and stored separately, and used separately during batching. Furthermore, impurities and mud in the recycled iron must be thoroughly cleaned.

[0029] In this embodiment, the quality of the scrap steel is required; the thickness of the scrap steel must be greater than or equal to 3 mm. Alloy steel is removed from the scrap steel. On the one hand, if the thickness of the scrap steel is less than 3 mm, severe corrosion will increase the gas content of the molten iron, causing oxidation and increased consumption of spheroidizing lines, resulting in poor spheroidization of the casting. On the other hand, if alloy steel is mixed into the scrap steel, it will cause iron carbide to form in the casting, reducing its plasticity and toughness.

[0030] In this embodiment, silicon carbide is used as the pretreatment agent. The particle size of silicon carbide is 0.2mm-1mm. In the process of molten iron smelting, silicon carbide plays multiple key roles as a pretreatment agent: On the one hand, silicon carbide has excellent deoxidation ability, effectively reducing the oxygen content in molten iron and reducing the formation of oxide inclusions, thereby improving the purity of molten iron; on the other hand, the silicon element produced by the decomposition of silicon carbide at high temperature can participate in the alloying process of molten iron, moderately increasing the silicon content of molten iron, laying a good foundation for subsequent spheroidizing treatment and casting performance control. At the same time, the carbon element produced by its decomposition also helps to stabilize the carbon equivalent of molten iron, avoiding the influence of excessive carbon content fluctuations on the microstructure and properties of castings.

[0031] The structural design of the spheroidizing reaction package is optimized so that the height-to-diameter ratio of the spheroidizing reaction package is 1.5-2.0. This height-to-diameter ratio design can prolong the residence time of molten iron in the spheroidizing chamber, promote full contact and reaction between the spheroidizing line and the molten iron, and reduce poor spheroidization caused by insufficient reaction time. The spheroidizing wire is made of silicon-magnesium-rare earth alloy Mg8RE3 (to introduce silicon and magnesium). During the spheroidizing process, the amount of spheroidizing wire added is 22-28 meters / ton (specifically 25 meters / ton), the wire feeding speed is 28-33 meters / minute (specifically 30 meters / minute), and the particle size of the spheroidizing wire is 220g / m-250g / m. Combined with the wire feeding spheroidizing process, the spheroidizing wire is precisely fed in at an addition amount of 22-28 meters / ton (specifically 25 meters / ton) and a wire feeding speed of 28-33 meters / minute (30 meters / minute). This allows the key elements such as silicon, magnesium, and rare earth in the spheroidizing wire to be evenly dispersed in the molten iron. This avoids the magnesium element burn-out and splashing caused by excessively high local concentration of spheroidizing wire and overly violent reaction in the traditional injection method. It significantly improves the utilization rate of the spheroidizing wire and the stability of the spheroidizing reaction, thereby ensuring the consistency of the spheroidization rate of the casting.

[0032] Specifically, as shown in Table 2, the composition of the spheroidizing line includes silicon, calcium, magnesium, aluminum, rare earth elements, and magnesium oxide. The mass percentages of silicon, calcium, magnesium, aluminum, rare earth elements, and magnesium oxide are 40%-50%, 2%-3.5%, 23%-30%, 0.5%-1.2%, 1.8%-3%, and 0.8%-2%, respectively. By controlling the amount of spheroidizing line added, the mass of relevant elements added to the molten iron can be reasonably adjusted. The addition of aluminum is used for deoxidation to control the oxygen content in the molten iron. The addition of rare earth elements ensures the content of rare earth elements in the final molten iron (rare earth elements can effectively promote graphite spheroidization, causing graphite to precipitate in a spherical shape, reducing stress concentration and improving the toughness of cast iron). Moreover, the addition of magnesium oxide in the spheroidizing line, since magnesium oxide has a greater affinity for sulfur in the molten iron than iron, can effectively reduce the sulfur content in the molten iron, creating favorable conditions for subsequent spheroidizing treatment.

[0033] During the spheroidizing process, it is important to control the degree of oxidation of the molten iron: severe oxidation of the molten iron not only results in significant element loss and a greater tendency for white iron formation, but also consumes a large amount of magnesium and rare earth elements, often leading to poor spheroidization. Secondly, at this stage, the fluidity of the molten iron is poor, and defects such as slag inclusions, shrinkage cavities, and subcutaneous porosity are severe. Immediate measures must be taken to analyze the causes, add carburizing agents, and prevent the addition of severely corroded scrap steel.

[0034] It should be noted that in this embodiment, the inoculation line is a SiBaCa (silicon-barium-calcium alloy) inoculation line, with an addition amount of 22-28 meters per ton, a feeding speed of 28-33 meters per minute, and a particle size of 255g / m-285g / m. By controlling the amount of inoculation line added, the appropriate addition of relevant elements is controlled. Specifically, the composition of the inoculation line includes silicon, calcium, aluminum, and barium, with mass percentages of silicon, calcium, aluminum, and barium of 65%-75%, 1%-3%, 0.8%-1.4%, and 2.5%-3.8%, respectively. The inoculation line further adjusts the silicon content in the molten iron, and barium is added. Barium improves product quality by purifying the molten iron and promoting graphitization.

[0035] During wire feeding inoculation, the inoculation line is precisely fed into the molten iron following the spheroidizing line. Utilizing its uniform mixing and rapid reaction with the molten iron, it significantly reduces the supercooling of the molten iron, minimizes the formation of white iron structure, and improves the morphology and distribution of graphite, further enhancing the mechanical properties of the casting. Compared to in-flow or pouring inoculation methods, wire feeding inoculation avoids the problems of insufficient or declining inoculation caused by the inoculant floating on the surface of the molten iron and uneven distribution. This results in a more stable and lasting inoculation effect, ensuring uniform performance across all parts of the casting. Especially for complex castings with significant differences in wall thickness, it effectively reduces deviations in microstructure and properties caused by varying cooling rates.

[0036] Specifically, the primary inoculant uses SiBaCa (silicon-barium-calcium alloy), with the same composition as the aforementioned inoculation line. The particle size of the primary inoculant is 3mm-8mm, which also plays the role of controlling the content of various components in the molten iron. In addition, the secondary inoculant used in the inflow process is Y-SiBi inoculant (silicon-bismuth inoculant). The particle size of the inoculant is 0.2mm-0.7mm, and its addition amount is controlled between 0.15%-0.25% of the weight of the molten iron. During the flow of molten iron, the inoculant is uniformly added to the molten iron flow through a dedicated inoculation device to achieve secondary inoculation enhancement of the molten iron. The bismuth element in the Y-SiBi inoculant can strongly promote graphite nucleation, forming a synergistic effect with wire feeding inoculation, further refining the graphite particle size and improving the roundness of the graphite. At the same time, the silicon element can supplement the silicon content in the molten iron, ensuring the matrix structure and properties of the casting.

[0037] By adding silicon to the pretreatment agent, spheroidizing line, inoculation line, primary inoculator, and secondary inoculator, the oxygen content in the molten steel or iron is reduced at each step, non-metallic inclusions are decreased, and the purity and fluidity of the molten iron are improved. Calcium is added to the spheroidizing line, inoculation line, primary inoculator, and secondary inoculator. Calcium can react with impurities in the molten iron, improving the quality of the molten iron and the efficiency of subsequent processing. While calcium is not suitable to be added to the pretreatment agent used in the pretreatment process, it is sufficient to achieve the desired casting effect in other steps before and after pretreatment.

[0038] Table 1. Information on spheroidization lines, incubation lines, pretreatment agents, and incubation agents.

[0039] After inoculation and spheroidizing treatment, the molten iron in the spheroidizing chamber contains carbon, silicon, manganese, phosphorus and sulfur, magnesium, and rare earth elements. The mass percentages of carbon, silicon, manganese, phosphorus and sulfur, magnesium, and rare earth elements are 3.4%-3.8%, 2.6%-2.9%, 0.15%-0.2%, ≤0.06%, ≤0.02%, 0.04%-0.06%, and 0.02%-0.04%, respectively. Precise control of the content of each element in the molten iron enables precise regulation of the microstructure and graphite morphology of the ductile iron matrix. Carbon and silicon, as the main elements, provide sufficient carbon-silicon equivalents for the precipitation and growth of graphite, ensuring the quantity and morphology of graphite. Manganese plays an important role in limiting pearlite formation and refining grains, and its content is strictly controlled to avoid increased casting brittleness caused by excessive manganese. Phosphorus and sulfur effectively prevent the formation of phosphorus eutectic and sulfide inclusions, thereby significantly improving the toughness and plasticity of castings. Magnesium and rare earth elements are the core of spheroidization treatment. The magnesium content is controlled at 0.04%-0.06%, ensuring the sufficiency and stability of graphite spheroidization. The rare earth element content is 0.02%-0.04%, which not only enhances the spheroidization ability of magnesium, but also effectively neutralizes interfering elements in molten iron, optimizing the roundness and uniformity of graphite spheres.

[0040] It should be noted that by controlling the spheroidizing line, inoculant particle size, and feeding speed, the spheroidizing line and inoculant will not break prematurely. If the broken alloy is stored for a long time, the surface is prone to oxidation. For as-cast QT400-18 ductile iron, a silicon-bismuth inoculant is used instead of a dedicated inoculant, and three inoculation processes are performed. In each inoculation process, the amount of silicon-bismuth inoculant added is 0.1% of the tapped iron mass.

[0041] During the casting process, pre-furnace inspection is required: pour a triangular test piece, break it, and observe the fracture surface: the test piece has shrinkage on both sides, the fracture surface is silver-gray, the structure is dense, there is shrinkage porosity in the center, after quenching, there is an acetylene odor, and the spheroidization is good.

[0042] Inspection during the casting process: Before casting and during the final pour, cast round test bars with a diameter of 20 mm. After cooling to a dark red (600°C) temperature... o C-700 o C) When immersed in water, the cylindrical test bar is broken in the middle. The fracture surface is silvery-gray, the structure is dense, and there is shrinkage porosity in the center. After quenching, it has an acetylene odor and good spheroidization.

[0043] Mechanical properties and metallographic examination: Cast Y-shaped integral test blocks are packaged together with the castings and then machined for relevant inspections. One integral Y-shaped test block is used for inspection in each package, and the test specimen is numbered with the date + furnace number + furnace sequence.

[0044] Example 2 This embodiment provides an application of the casting process for ball mill castings using wire feeding spheroidizing casting, which is applied to the casting of wind turbine bearing frames; When casting wind turbine bearing frames (with a maximum thickness of 110mm), a composite inoculation process using 75Si iron and a silicon-barium alloy is employed instead of the aforementioned inoculation line. The mass percentages of silicon, barium, aluminum, and calcium in the 75Si iron and silicon-barium alloy are 60%-68%, 4%-6%, 1.0%-2.0%, and 0.8%-2.2%, respectively. This inoculation method effectively promotes graphite refinement and spheroidization, reduces defects such as white iron structure, shrinkage cavities, and porosity that may occur during casting, and significantly improves the density and mechanical properties of the wind turbine bearing frame castings. Silicon, as the main inoculating agent, strongly promotes graphite nucleation; barium effectively delays the growth of austenite dendrites and refines the grains; and the appropriate ratio of aluminum and calcium helps improve the sphericity and uniformity of graphite spheroids, thereby ensuring that the wind turbine bearing frame possesses good wear resistance, toughness, and fatigue strength under complex loads, meeting the stringent requirements for long-term stable operation of large wind power equipment.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A casting process for ball mill castings using wire-feed spheroidizing casting, characterized in that, Includes the following: Scrap steel and recycled iron are added to the furnace, followed by pig iron, and then smelted to form molten iron. The composition of the molten iron is finely adjusted to include carbon, silicon, manganese, phosphorus, and sulfur, with the following mass percentages: 3.7%-3.9%, 1.0%-1.5%, 0.1%-0.3%, ≤0.06%, and ≤0.05%, respectively. Raise the temperature of the molten iron to 1520℃-1530℃, keep it at that temperature and let it stand for a set time; Spheroidization and incubation treatment: When spheroidizing lines are added to molten iron, they introduce silicon and magnesium during the process. Adding the inoculation line to the molten iron introduces silicon during the process. Iron pretreatment: Before tapping the molten iron, a pretreatment agent is added at the tapping trough. The mass of the pretreatment agent is 0.25%-0.35% of the tapped iron mass. Silicon is introduced during the pretreatment process. Inoculation treatment: Add a primary inoculant to the spheroidizing chamber of the spheroidizing reaction package. The mass of the primary inoculant is 0.5%-0.7% of the iron output mass, and it also introduces silicon. The casting temperature is controlled at 1400℃-1370℃. A secondary inoculant is added during casting, which is 0.09%-0.15% of the iron mass and carries in silicon. Stop pouring after the set time.

2. The casting process for ball mill castings using wire-feed spheroidizing casting according to claim 1, characterized in that, The amount of spheroidizing line added is 22-28 meters / ton, and the feeding speed is 28-33 meters / minute.

3. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, The spheroidized line is composed of silicon, calcium, magnesium, aluminum, rare earth elements and magnesium oxide, with the mass percentages of silicon, calcium, magnesium, aluminum, rhenium and magnesium oxide being 40%-50%, 2%-3.5%, 23%-30%, 0.5%-1.2%, 1.8%-3% and 0.8%-2%, respectively.

4. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, The inoculation line is a SiBaCa inoculation line, with an addition amount of 22 m / ton to 28 m / ton and a feeding speed of 28 m / min to 33 m / min; The incubation line is composed of silicon, calcium, aluminum and barium, with the mass percentages of silicon, calcium, aluminum and barium being 65%-75%, 1%-3%, 0.8%-1.4% and 2.5%-3.8%, respectively.

5. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1 or 3, characterized in that, The primary inoculant is SiBaCa inoculant, and the secondary inoculant is Y-SiBi inoculant.

6. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, The pretreatment agent has a particle size of 0.2mm-1mm, the primary inoculant has a particle size of 3mm-8mm, and the secondary inoculant has a particle size of 0.2mm-0.7mm. The particle size of the spheroidizing lines is 220g / m-250g / m, and the particle size of the inoculation lines is 255g / m-285g / m.

7. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, After the inoculation and spheroidizing treatment, the molten iron in the spheroidizing chamber comprises carbon, silicon, manganese, phosphorus, sulfur, magnesium, and rare earth elements, with the following mass percentages: 3.4%-3.8%, 2.6%-2.9%, 0.15%-0.2%, ≤0.06%, ≤0.02%, 0.04%-0.06%, and 0.02%-0.04%, respectively.

8. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, The spheroidization line is a silicon-magnesium rare earth alloy Mg8RE3.

9. The casting process for ball mill castings using wire-feeding spheroidizing casting according to claim 1, characterized in that, The height-to-diameter ratio of the spheroidizing reaction package is 1.5-2.

0.

10. The application of the casting process for ball mill castings using wire-feeding spheroidizing casting according to any one of claims 1-9, characterized in that, Casting for wind turbine bearing frames; When casting the wind turbine bearing frame, 75Si iron and silicon-barium alloy are used instead of the inoculation line for composite inoculation. The mass percentages of silicon, barium, aluminum and calcium in the 75Si iron and silicon-barium alloy are 60%-68%, 4%-6%, 1.0%-2.0% and 0.8%-2.2%, respectively.

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