High-strength machine tool casting and preparation method thereof

Abstract

The invention belongs to the technical field of metal casting, and particularly relates to a high-strength machine tool casting and a preparation method thereof. The preparation method of the machine tool casting comprises the following steps: S1, weighing the following raw materials in parts by weight: 150-200 parts of pig iron, 200-300 parts of waste steel, 50-100 parts of foundry returns, 10-20 parts of modified basalt fibers, 1-5 parts of neodymium fluoride powder, 1-3 parts of ferromanganese, 10-20 parts of a carburant, 1-4 parts of an in-ladle inoculant and 0.5-1 part of a stream inoculant for later use; s2, after the waste steel is heated, pig iron, foundry returns and a carburant are added, after the temperature continues to rise, neodymium fluoride powder and ferromanganese are added, and molten iron is obtained after discharging; s3, the molten iron in the step S2 is added into an in-ladle nucleating agent for inoculation treatment, and the molten iron subjected to inoculation treatment is obtained; and adding a stream inoculant and the modified basalt fiber during casting, and forming to obtain the machine tool casting. The machine tool casting obtained through the method has high strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal casting, and particularly relates to a high-strength machine tool casting and a preparation method thereof. Background Art

[0002] The machine tool industry, as an important pillar and cornerstone of the national economic development, can be regarded as the "heart" of the manufacturing industry and the core "mother machine". It not only promotes the technological progress and industrial upgrading of all walks of life, but also directly relates to the strength of a country's industrial strength and the competitiveness of the manufacturing industry. High-end machine tools, as the outstanding ones in the machine tool industry, need to have excellent machining accuracy, high machining ability, stable, reliable and durable quality. The realization of these characteristics is inseparable from the support of the basic component of machine tool castings. The performance of machine tool castings directly affects the overall performance and service life of machine tools. However, with the rapid development and continuous progress of technology, traditional machine tool castings are difficult to meet the stringent requirements of current high-end machine tool equipment. Traditional castings have limitations in terms of strength, hardness, elastic modulus, etc., and cannot fully meet the requirements of high-precision, high-efficiency and high-stability of high-end machine tools.

[0003] Based on the above background, the present invention aims to provide a preparation method that can significantly improve the strength of castings while maintaining high hardness and high elastic modulus, with the expectation of greatly extending the service life of machine tools and improving processing efficiency. Summary of the Invention

[0004] The first object of the present invention is to provide a preparation method for high-strength machine tool castings, with simple steps and easy for batch production.

[0005] The second object of the present invention is to provide a high-strength machine tool casting with excellent strength performance.

[0006] In order to achieve the above objects, the technical solution adopted by the present invention is:

[0007] A preparation method for high-strength machine tool castings includes the following steps:

[0008] S1. Weigh the following raw materials in parts by weight: 150 - 200 parts of pig iron, 200 - 300 parts of scrap steel, 50 - 100 parts of return material, 10 - 20 parts of modified basalt fiber, 1 - 5 parts of neodymium fluoride powder, 1 - 3 parts of ferromanganese, 10 - 20 parts of carbon additive, 1 - 4 parts of in-package inoculant, 0.5 - 1 part of stream inoculant, and set aside;

[0009] S2. Heat the scrap steel and then add pig iron, return material, and carbon additive. After further heating, add neodymium fluoride powder and ferromanganese, and obtain molten iron after tapping.

[0010] S3. Add the molten iron from step S2 to the in-package inoculant for inoculation treatment to obtain the inoculated molten iron; add the in-stream inoculant and modified basalt fiber during casting, and the machine tool casting can be obtained after molding.

[0011] Preferably, the preparation process of the modified basalt fiber is as follows:

[0012] (1) Remove the surface impurities of the basalt fiber and then soak it in an acid solution to obtain acid-treated basalt fiber;

[0013] (2) Add the acid-treated basalt fiber from step (1) and cetyltrimethoxysilane to an aqueous solution of ethanol for heating reaction to obtain a reaction solution;

[0014] (3) Add the pretreated diatomite to the reaction solution from step (2) for stirring reaction to obtain the modified basalt fiber.

[0015] Preferably, in step (3), the dosage ratio of the pretreated diatomite to the reaction solution is 1 g:(250 - 400) mL; the temperature of the stirring reaction is 50 - 60 °C, and the time of the stirring reaction is 1 - 2 h.

[0016] Preferably, the preparation method of the pretreated diatomite is:

[0017] At 60 - 70 °C, treat the diatomite with nitric acid for 5 - 7 h, wash it to neutrality and then calcine it at 350 - 450 °C for 0.5 - 1.5 h to obtain a product; disperse the product in water, then add sodium dodecylbenzenesulfonate, adjust the pH of the system to 2 - 3, react for 4 - 7 h, and then obtain the pretreated diatomite through standing, washing, and vacuum drying.

[0018] Preferably, the concentration of the nitric acid is 1 - 3 mol / L; the mass ratio of the product to sodium dodecylbenzenesulfonate is 1:(2 - 4).

[0019] Preferably, in step (2), the dosage ratio of the acid-treated basalt fiber, cetyltrimethoxysilane, and the aqueous solution of ethanol is 1 g:(50 - 100) mL:(80 - 120) mL; the concentration of the aqueous solution of ethanol is 40 - 50 wt%; the temperature of the heating reaction is 110 - 120 °C, and the time of the heating reaction is 2 - 3 h.

[0020] Preferably, in step (1), the temperature of the soaking treatment is 25 - 35 °C, and the time of the soaking treatment is 30 - 45 min; the acid solution is a 0.1 - 0.2 mol / L hydrochloric acid solution.

[0021] Preferably, in step S2, the temperature is raised to 1050 - 1100 °C and then continuously raised to 1550 - 1580 °C; the temperature for discharging from the furnace is 1450 - 1500 °C; and the temperature for casting in step S3 is 1300 - 1350 °C.

[0022] Preferably, the recarburizer is a graphite recarburizer, the in-package inoculant is composed of a barium-silicon inoculant and a 75% ferrosilicon inoculant with a mass ratio of (2 - 3):1, and the in-stream inoculant is a barium-silicon inoculant.

[0023] A high-strength machine tool casting is prepared by using the above preparation method for high-strength machine tool castings.

[0024] Compared with the prior art, the beneficial effects of the present invention mainly lie in:

[0025] 1. The raw materials of the high-strength machine tool casting of the present invention include components such as modified basalt fiber and neodymium fluoride powder. Testing the performance of the machine tool casting obtained in the present invention reveals that the combined use of neodymium fluoride powder and modified basalt fiber can improve the organizational structure of the machine tool casting, and thus improve the strength of the machine tool casting. Specifically, the acid treatment of basalt fiber in the present invention can partially decompose the silicate structure on its surface, exposing more hydroxyl groups, and then reacting with cetyltrimethoxysilane to generate network cross-linking through silane groups, thereby improving the interfacial bonding ability of basalt fiber and enhancing the dispersibility of basalt fiber; at the same time, the porous and electrostatic adsorption effects of pretreated diatomite are used to further modify basalt fiber to improve the stability of its dispersion. The addition of neodymium fluoride powder can promote the uniform distribution of various elements in the molten iron, avoiding the uneven alloying phenomenon caused by element enrichment.

[0026] 2. The present invention also provides the preparation method of the above high-strength machine tool casting, and this method has simple steps and is easy for batch production. Specific Embodiments

[0027] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0028] 1. Preparation Examples

[0029] Preparation Example 1

[0030] This preparation example provides a modified basalt fiber, and the specific preparation process is as follows:

[0031] (1) Immerse the basalt fiber in acetone for 3 h to remove surface impurities. After taking it out, add it to a 0.15 mol / L hydrochloric acid solution and soak it at 30 °C for 40 min. Then wash it with deionized water until neutral, and obtain acid-treated basalt fiber after vacuum drying.

[0032] (2) According to the dosage ratio of acid-treated basalt fiber, cetyltrimethoxysilane, and aqueous ethanol solution of 1 g: 80 mL: 100 mL, add the acid-treated basalt fiber and cetyltrimethoxysilane in step (1) to an aqueous solution of 45 wt% ethanol, and heat and react at 115 °C for 2.5 h to obtain a reaction solution.

[0033] (3) At 65 °C, treat diatomite with 2 mol / L nitric acid for 6 h, wash it until neutral, and then calcine it at 400 °C for 1 h to obtain a product; according to the mass ratio of the product to sodium dodecylbenzenesulfonate of 1: 3, disperse the product in water, then add sodium dodecylbenzenesulfonate, use 0.1 mol / L hydrochloric acid to adjust the pH of the system to 2, and then stir and react at room temperature for 6 h. After standing, washing, and vacuum drying, obtain pretreated diatomite.

[0034] According to the dosage ratio of pretreated diatomite to the reaction solution of 1 g: 300 mL, add the pretreated diatomite to the reaction solution in step (2), stir and react at 55 °C for 1.5 h, and obtain modified basalt fiber after filtration and vacuum drying.

[0035] Preparation Example 2

[0036] This preparation example provides a modified basalt fiber, and the specific preparation process is as follows:

[0037] (1) Immerse the basalt fiber in acetone for 3 h to remove surface impurities. After taking it out, add it to a 0.1 mol / L hydrochloric acid solution and soak it at 25 °C for 45 min. Then wash it with deionized water until neutral, and obtain acid-treated basalt fiber after vacuum drying.

[0038] (2) According to the dosage ratio of acid-treated basalt fiber, cetyltrimethoxysilane, and aqueous ethanol solution of 1 g: 50 mL: 80 mL, add the acid-treated basalt fiber and cetyltrimethoxysilane in step (1) to an aqueous solution of 40 wt% ethanol, and heat and react at 110 °C for 3 h to obtain a reaction solution.

[0039] (3) At 60 °C, treat diatomaceous earth with 1 mol / L nitric acid for 7 h, wash it until neutral, and then calcine it at 350 °C for 1.5 h to obtain a product; disperse the product in water at a mass ratio of the product to sodium dodecylbenzenesulfonate of 1:2, add sodium dodecylbenzenesulfonate, adjust the pH of the system to 2 with 0.1 mol / L hydrochloric acid, and then stir and react at room temperature for 4 h. After standing, washing, and vacuum drying, pretreated diatomaceous earth is obtained.

[0040] Add the pretreated diatomaceous earth to the reaction solution in step (2) at a dosage ratio of 1 g of pretreated diatomaceous earth to 250 mL of the reaction solution, stir and react at 50 °C for 2 h, and obtain modified basalt fibers after filtration and vacuum drying.

[0041] Preparation Example 3

[0042] This preparation example provides a kind of modified basalt fiber, and the specific preparation process is as follows:

[0043] (1) Immerse basalt fibers in acetone for 3 h to remove surface impurities. After taking them out, add them to a 0.2 mol / L hydrochloric acid solution, soak and treat them at 35 °C for 30 min, and then wash them with deionized water until neutral. After vacuum drying, acid-treated basalt fibers are obtained.

[0044] (2) At a dosage ratio of 1 g of acid-treated basalt fibers, 100 mL of cetyltrimethoxysilane, and 120 mL of an aqueous solution of ethanol, add the acid-treated basalt fibers and cetyltrimethoxysilane in step (1) to an aqueous solution of 50 wt% ethanol, heat and react at 120 °C for 2 h to obtain a reaction solution.

[0045] (3) At 70 °C, treat diatomaceous earth with 3 mol / L nitric acid for 5 h, wash it until neutral, and then calcine it at 450 °C for 0.5 h to obtain a product; disperse the product in water at a mass ratio of the product to sodium dodecylbenzenesulfonate of 1:4, add sodium dodecylbenzenesulfonate, adjust the pH of the system to 3 with 0.1 mol / L hydrochloric acid, and then stir and react at room temperature for 7 h. After standing, washing, and vacuum drying, pretreated diatomaceous earth is obtained.

[0046] Add the pretreated diatomaceous earth to the reaction solution in step (2) at a dosage ratio of 1 g of pretreated diatomaceous earth to 400 mL of the reaction solution, stir and react at 60 °C for 1 h, and obtain modified basalt fibers after filtration and vacuum drying.

[0047] Preparation Example 4

[0048] This preparation example provides a kind of modified basalt fiber, which is different from Preparation Example 1 in that diatomaceous earth is used instead of pretreated diatomaceous earth, and the rest of the preparation conditions and raw material dosages are the same as those in Preparation Example 1.

[0049] 2. Examples

[0050] Example 1

[0051] This example provides a method for preparing a high-strength machine tool casting, which is as follows:

[0052] S1. Weigh the following raw materials by weight: 160 parts of pig iron, 220 parts of scrap steel, 70 parts of return material, 13 parts of the modified basalt fiber prepared in Preparation Example 1, 4 parts of neodymium fluoride powder, 2 parts of ferromanganese, 11 parts of graphite carburizer, 2 parts of in-mold inoculant, and 0.6 parts of silicon-barium inoculant, and set aside; among them, the in-mold inoculant is composed of silicon-barium inoculant (Si: 69 - 72%, Ca: 2.1 - 2.8%, Ba: 1.3 - 2.5%, the balance is Fe) and 75 ferrosilicon inoculant (Si: 73 - 75%, Al ≤ 0.3%, the balance is Fe) with a mass ratio of 3:1;

[0053] S2. Add the scrap steel to the electric furnace, heat it to 1080 °C, then add the pig iron, return material, and graphite carburizer, continue to heat it to 1560 °C, then add the neodymium fluoride powder and ferromanganese, and obtain the molten iron after discharging at 1480 °C;

[0054] S3. Heat the molten iron pouring ladle to 700 °C for drying, then add the in-mold inoculant at the bottom of the molten iron pouring ladle. The bottom of the ladle is flat. Quickly pour the molten iron in step S2 into the molten iron pouring ladle, stir the molten iron to melt the inoculant, and obtain the inoculated molten iron after slag removal; pour the inoculated molten iron into the mold and carry out casting at 1320 °C. When casting, add the silicon-barium inoculant and the modified basalt fiber with the flow, and the machine tool casting is obtained after molding.

[0055] This example also provides a high-strength machine tool casting prepared by the above preparation method.

[0056] The composition of the above high-strength machine tool casting by weight percentage includes: modified basalt fiber: 2.69%; C: 2.05%; Mn: 0.35%; Si: 0.35%; the rest are iron and impurities.

[0057] Example 2

[0058] This example provides a method for preparing a high-strength machine tool casting, which is as follows:

[0059] S1. Weigh the following raw materials by weight: 200 parts of pig iron, 300 parts of scrap steel, 100 parts of return material, 20 parts of the modified basalt fiber prepared in Preparation Example 2, 5 parts of neodymium fluoride powder, 3 parts of ferromanganese, 20 parts of graphite carburizer, 4 parts of in-mold inoculant, and 1 part of silicon-barium inoculant, and set aside. The in-mold inoculant consists of silicon-barium inoculant (Si: 69 - 72%, Ca: 2.1 - 2.8%, Ba: 1.3 - 2.5%, the balance is Fe) and 75% ferrosilicon inoculant (Si: 73 - 75%, Al ≤ 0.3%, the balance is Fe) with a mass ratio of 4:1;

[0060] S2. Add the scrap steel to an electric furnace, heat it to 1100 °C, then add the pig iron, return material, and graphite carburizer, continue to heat it to 1580 °C, add the neodymium fluoride powder and ferromanganese, and obtain molten iron after tapping at 1500 °C;

[0061] S3. Heat the molten iron pouring ladle to 700 °C for drying, then add the in-mold inoculant to the bottom of the molten iron pouring ladle. The bottom of the ladle is flat. Quickly pour the molten iron from step S2 into the molten iron pouring ladle, stir the molten iron to melt the inoculant, and obtain the inoculated molten iron after slag removal. Pour the inoculated molten iron into a mold and carry out casting at 1350 °C. During casting, add silicon-barium inoculant and modified basalt fiber with the flow, and the machine tool casting is obtained after molding.

[0062] This example also provides a high-strength machine tool casting prepared by the above preparation method.

[0063] The composition of the above high-strength machine tool casting by weight percentage includes: modified basalt fiber: 3.06%; C: 2.75%; Mn: 0.39%; Si: 0.51%; the rest is iron and impurities.

[0064] Example 3

[0065] This example provides a preparation method of a high-strength machine tool casting, which is as follows:

[0066] S1. Weigh the following raw materials by weight: 150 parts of pig iron, 200 parts of scrap steel, 50 parts of return material, 10 parts of the modified basalt fiber prepared in Preparation Example 3, 1 part of neodymium fluoride powder, 1 part of ferromanganese, 10 parts of graphite carburizer, 1 part of in-mold inoculant, and 0.5 part of silicon-barium inoculant, and set aside. The in-mold inoculant consists of silicon-barium inoculant (Si: 69 - 72%, Ca: 2.1 - 2.8%, Ba: 1.3 - 2.5%, the balance is Fe) and 75% ferrosilicon inoculant (Si: 73 - 75%, Al ≤ 0.3%, the balance is Fe) with a mass ratio of 2:1;

[0067] S2. Add scrap steel to the electric furnace, heat it up to 1050 °C, then add pig iron, return scrap, and graphite carburizer. Continue to heat it up to 1550 °C, then add neodymium fluoride powder and ferromanganese. After tapping at 1450 °C, molten iron is obtained.

[0068] S3. Heat the molten iron pouring ladle to 700 °C and dry it. Then add the in-ladle inoculant at the bottom of the ladle. The bottom of the ladle is flat. Quickly pour the molten iron from step S2 into the molten iron pouring ladle, stir the molten iron to melt the inoculant, and remove the slag to obtain the inoculated molten iron. Pour the inoculated molten iron into the mold and cast it at 1300 °C. During casting, add silicon-barium inoculant and modified basalt fiber with the flow. After forming, the machine tool casting is obtained.

[0069] This embodiment also provides a high-strength machine tool casting prepared by the above preparation method.

[0070] The composition of the above high-strength machine tool casting by weight percentage includes: modified basalt fiber: 2.36%; C: 2.12%; Mn: 0.20%; Si: 0.23%; the rest is iron and impurities.

[0071] 3. Comparative Examples

[0072] Comparative Example 1

[0073] This comparative example provides a preparation method of a machine tool casting, which is different from that of Example 1 in that: basalt fiber is used instead of modified basalt fiber, and the rest is the same as that of Example 1.

[0074] This comparative example also provides a machine tool casting prepared by the above preparation method.

[0075] Comparative Example 2

[0076] This comparative example provides a preparation method of a machine tool casting, which is different from that of Example 1 in that: the modified basalt fiber of Preparation Example 4 is used instead of the modified basalt fiber of Preparation Example 1, and the rest is the same as that of Example 1.

[0077] This comparative example also provides a machine tool casting prepared by the above preparation method.

[0078] Comparative Example 3

[0079] This comparative example provides a preparation method of a machine tool casting, which is different from that of Example 1 in that: neodymium fluoride powder is omitted, and the rest is the same as that of Example 1.

[0080] This comparative example also provides a machine tool casting prepared by the above preparation method.

[0081] 4. Test Examples

[0082] The properties of the machine tool castings prepared in Examples 1-3 and Comparative Examples 1-3 were detected. The detection methods and indexes are as follows:

[0083] Brinell hardness: The test was carried out with reference to GB / T231.2-2022. The test result was the average value of 5 test results, and the results are shown in Table 1;

[0084] Tensile strength: The test was carried out with reference to GB / T228.1-2021. The test result was the average value of 5 test results, and the results are shown in Table 1;

[0085] Elastic modulus: The test was carried out with reference to GB / T22315-2008. The test result was the average value of 5 test results, and the results are shown in Table 1.

[0086] Table 1

[0087] Sample Tensile strength / MPa Brinell hardness / HBC Elastic modulus / GPa Example 1 396 215 144 Example 2 395 212 143 Example 3 393 211 140 Comparative example 1 368 202 131 Comparative example 2 382 207 136 Comparative example 3 376 205 133

[0088] It can be seen from observing Table 1 that compared with Comparative Examples 1-3, the machine tool castings prepared in Examples 1-3 can significantly improve the strength of the castings while maintaining high hardness and high elastic modulus. In Comparative Example 1, the modified basalt fiber was replaced with basalt fiber. In Comparative Example 2, the preparation process of the modified basalt fiber was adjusted. In Comparative Example 3, the neodymium fluoride powder was omitted. The above results show that the combined use of modified basalt fiber and neodymium fluoride powder can improve the strength of the castings. Specifically, in the present invention, acid treatment of basalt fiber can decompose part of the silicate structure on its surface, expose more hydroxyl groups, and then react with cetyltrimethoxysilane to generate network cross-linking through silane groups, thereby improving the interfacial bonding ability of basalt fiber and enhancing the dispersibility of basalt fiber; at the same time, the porous and electrostatic adsorption effects of pretreated diatomite are used to further modify basalt fiber to improve the stability of its dispersion. The addition of neodymium fluoride powder can promote the uniform distribution of each element in the molten iron water and avoid the uneven alloying phenomenon caused by element enrichment. To sum up, the combined use of neodymium fluoride powder and modified basalt fiber can improve the organizational structure of the machine tool casting, and thus improve the strength of the machine tool casting.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. The basic principles and main features of the present invention have been described with specific implementation schemes above. On the basis of the present invention, some modifications or replacements can be made, but these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of protection required by the present invention.

Claims

1. A method for preparing a high-strength machine tool casting, characterized in that: The steps include: S1. In parts by weight, weigh the following raw materials: 150-200 parts of pig iron, 200-300 parts of scrap steel, 50-100 parts of recycled materials, 10-20 parts of modified basalt fiber, 1-5 parts of neodymium fluoride powder, 1-3 parts of ferromanganese, 10-20 parts of recarburizer, 1-4 parts of inoculant in the bag, 0.5-1 parts of flow inoculant, set aside; S2. After heating the scrap steel, pig iron, recycled materials, and carburizer are added, and after continuing to heat, neodymium fluoride powder and ferromanganese are added to obtain molten iron after being discharged from the furnace; S3. Add the molten iron of step S2 to the inoculant in the ladle for inoculation treatment to obtain the molten iron after inoculation treatment; add the inoculant and modified basalt fiber during casting, and obtain the machine tool casting after molding.

2. The method for preparing a high-strength machine tool casting according to claim 1, characterized in that: The preparation process of the modified basalt fiber is as follows: (1) removing surface impurities from basalt fibers and then adding them into an acid solution for immersion treatment to obtain acid-treated basalt fibers; (2) adding the acid-treated basalt fiber and hexadecyltrimethoxysilane of step (1) to an aqueous solution of ethanol for heating reaction to obtain a reaction solution; (3) adding the pretreated diatomaceous earth to the reaction solution of step (2) for stirring reaction to obtain modified basalt fiber.

3. The method for preparing a high-strength machine tool casting according to claim 2, characterized in that: In step (3), the ratio of the pretreated diatomaceous earth to the reaction solution is 1 g: (250-400) mL; the temperature of the stirring reaction is 50-60° C., and the time of the stirring reaction is 1-2 h.

4. The method for preparing a high-strength machine tool casting according to claim 3, characterized in that: The preparation method of the pretreated diatomaceous earth is: Treat diatomaceous earth with nitric acid at 60-70°C for 5-7h, wash to neutrality and then calcine at 350-450°C for 0.5-1.5h to obtain the product; The product is dispersed in water, and then sodium dodecylbenzene sulfonate is added to adjust the pH of the system to 2-3. After reacting for 4-7 hours, the pretreated diatomaceous earth is obtained by standing, washing and vacuum drying.

5. The method for preparing a high-strength machine tool casting according to claim 4, characterized in that: The concentration of the nitric acid is 1-3 mol / L; the mass ratio of the product to sodium dodecylbenzene sulfonate is 1:(2-4).

6. The method for preparing a high-strength machine tool casting according to claim 2, characterized in that: In step (2), the amount ratio of the acid-treated basalt fiber, hexadecyltrimethoxysilane, and ethanol aqueous solution is 1 g: (50-100) mL: (80-120) mL; the concentration of the ethanol aqueous solution is 40-50 wt %; the temperature of the heating reaction is 110-120° C., and the heating reaction time is 2-3 h.

7. The method for preparing a high-strength machine tool casting according to claim 2, characterized in that: The soaking temperature in step (1) is 25-35° C., and the soaking time is 30-45 min. The acid solution is a 0.1-0.2 mol / L hydrochloric acid solution.

8. The method for preparing a high-strength machine tool casting according to claim 1, characterized in that: In step S2, the temperature is raised to 1050-1100°C, and then continued to be raised to 1550-1580°C; the temperature of the furnace is 1450-1500°C; and the casting temperature in step S3 is 1300-1350°C.

9. The method for preparing a high-strength machine tool casting according to claim 1, characterized in that: The recarburizer is a graphite recarburizer, the inoculant in the bag is composed of a silicon-barium inoculant and a 75% silicon-iron inoculant in a mass ratio of (2-4):1, and the inoculant is a silicon-barium inoculant.

10. A high-strength machine tool casting, characterized in that: The high-strength machine tool casting is prepared by the preparation method of any one of claims 1 to 9.