Manufacturing method of large ring steel casting sectioning ring

Abstract

The invention relates to the technical field of steel casting machining processes, in particular to a manufacturing method of a large ring type steel casting sectioning ring. Comprising the following steps that S1, a casting model is designed, and the casting model comprises at least two sectioning ring bodies; s2, every two adjacent sectioning ring bodies are connected through a connecting rib, the connecting ribs are arranged in the axial direction of the sectioning ring bodies, and the thickness of the connecting ribs is 50%-70% of the wall thickness of the corresponding positions of the sectioning ring bodies; s3, a casting pouring system is arranged; s4, a sand mold cavity is manufactured according to the shape and size of the casting model and the casting and pouring system, qualified molten steel is poured and then cooled along with molding sand, and after a pit is cooled to the temperature, the mold is knocked out of the pit to obtain an integral casting; s5, a feeding system and a casting and pouring system are removed from the integral casting, and an integral ring casting is obtained; s6, the whole-ring casting is put into a furnace to be subjected to heat treatment, and heat treatment comprises normalizing and tempering; and S7, cutting the qualified whole-ring casting subjected to heat treatment in the step S6 along the central line of the connecting rib, and dividing the whole-ring casting into split rings.

Description

Technical Field

[0001] The invention relates to the technical field of steel casting processing technology, in particular to a method for manufacturing a petal ring of a large-scale ring-type steel casting. Background Art

[0002] With the maturity and development of my country's large-scale hydropower unit technology and the construction of large power stations, the diameter of the turbine's core component, the runner, has also increased accordingly. The diameter of common large-scale runner steel castings reaches φ4000~7000mm. For higher-power hydropower stations, such as the Wudongde Hydropower Station and the Baihetan Hydropower Station, the runner diameter reaches 10 meters. For such large runners, due to road width and transportation capacity limitations, manufacturers are generally required to split the runner into petals before delivering it to the power station site, and then weld it into a runner at the site for production. The so-called petal splitting refers to dividing the runner evenly along the circumference into several equal parts (generally 2 to 4 equal parts), and each equal part of the runner is a petal ring. When the petal ring casting is supplied in petals, if the petal ring is cast as an independent steel casting, there are many manufacturing difficulties, which are mainly manifested as follows:

[0003] 1. As a separate curved surface, the thermal stress and tissue stress generated during the manufacturing process of the individual petal ring cannot be constrained, the stress deformation is uncontrolled, and the deformation generated is extremely difficult to repair by technological means.

[0004] 2. When loading a single split ring into a furnace for high temperature heat treatment, in order to ensure the mechanical properties of the product material and reduce deformation, it is better to load the product vertically. However, it is very difficult to load the single split ring vertically, and special matching furnace loading tooling is required. Due to the addition of the tooling, it is basically impossible to ensure that the heating or cooling uniformity of the casting is not affected.

[0005] 3. In order to offset the risk of shortage caused by deformation, more deformation correction and casting allowance need to be considered in the casting process design, which will lead to low utilization rate of casting molten steel and high manufacturing cost. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for manufacturing a large-scale ring-type steel casting split ring, which can ensure the internal quality of the split ring and reduce the manufacturing cost.

[0007] The technical solution adopted by the present invention to solve the technical problem is a method for manufacturing a large-scale ring-type steel casting petal ring, comprising the following steps:

[0008] S1: Design a casting model, the casting model includes at least two petal ring bodies, each of the petal ring bodies is provided with a shrinkage compensation system, the shrinkage compensation system includes a riser, inner and outer circumferential surfaces of the petal ring body, end surface design processing amount and casting correction amount;

[0009] S2: two adjacent petal ring bodies are connected by connecting ribs, which are arranged along the axial direction of the petal ring body, and the thickness of the connecting ribs is 50% to 70% of the wall thickness of the petal ring body at the corresponding position;

[0010] S3: Setting up a casting pouring system, wherein the casting pouring system includes a straight runner, a ring runner, an inner runner, a distribution position, a quantity and a runner cross-sectional size;

[0011] S4: Make a sand mold cavity according to the shape and size of the casting model and the casting pouring system, pour qualified molten steel and cool it along with the molding sand, and after the pit cools to the temperature, box it out of the pit to obtain the integral casting;

[0012] S5: removing the feeding system and the casting pouring system from the integral casting to obtain a full-ring casting;

[0013] S6: placing the whole ring casting into a furnace for heat treatment, wherein the heat treatment includes normalizing and tempering;

[0014] S7: The whole ring casting that has passed the S6 heat treatment is cut along the center line of the connecting rib to split the whole ring casting into petal rings and remove the connecting rib.

[0015] Further, in step S2, the width of the connecting rib is 50 mm to 100 mm.

[0016] Further, in step S6, the normalizing is to heat the whole ring casting to 100°C to 250°C above the Ac3 point of the material, keep it warm and then cool it quickly; the tempering is to heat the whole ring casting to 20°C to 30°C above the Ac1 point of the material, keep it warm and then cool it slowly; the normalizing and tempering temperature holding time is calculated according to the hot node diameter at the thickest position of the whole ring casting, and the insulation time is 3h to 5h for every 100mm.

[0017] Furthermore, after step S7, the method further includes the following step: S8: machining the inner and outer circular surfaces and the upper and lower end surfaces of the petal ring described in S7, and performing corresponding quality inspection and quality repair;

[0018] S9: Welding anti-deformation reinforcement bars on the inner surface of the petal ring that has passed the treatment in S8.

[0019] Furthermore, the anti-deformation reinforcement includes at least two first transverse ribs arranged at intervals along the axial direction of the petal ring, the first transverse ribs connecting the two radial ends of the inner surface of the petal ring, a second transverse rib is arranged between the first transverse rib and the inner surface of the petal ring, the second transverse rib is perpendicular to the first transverse rib, one end of the second transverse rib is connected to the first transverse rib, and the other end is connected to the inner surface of the petal ring, and two adjacent first transverse ribs are connected by longitudinal ribs.

[0020] Furthermore, the number of the first transverse ribs is determined according to the height of the petal ring, and one first transverse rib is provided at every 800 mm to 1000 mm in height.

[0021] Furthermore, the first transverse reinforcement, the second transverse reinforcement and the longitudinal reinforcement are rails or channel steels made of low carbon equivalent materials, and the effective cross-sectional areas of the first transverse reinforcement, the second transverse reinforcement and the longitudinal reinforcement are 3000-5000mm 2 .

[0022] Furthermore, a transition section made of the same material as the petal ring is provided at the connection between the first transverse rib and the petal ring and at the connection between the second transverse rib and the petal ring.

[0023] The beneficial effects of the present invention are as follows: This method addresses the problem of difficulty in manufacturing split rings by casting the entire ring followed by segmentation, which not only meets the internal quality of the product, but also effectively solves the problem of deformation during the product manufacturing process, improves the utilization rate of the product casting molten steel, and reduces the manufacturing difficulty and manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of the petal ring of the first embodiment;

[0025] Figure 2 It is a schematic structural diagram of the petal ring body of the first embodiment;

[0026] Figure 3 It is a structural schematic diagram of a casting model of the first embodiment;

[0027] Figure 4 Schematic diagram of the first embodiment of the split ring welding anti-deformation reinforcement;

[0028] Figure 5 is a schematic structural diagram of a petal ring according to a second embodiment;

[0029] Figure 6 is a schematic structural diagram of a petal ring body according to a second embodiment;

[0030] Figure 7 is a schematic structural diagram of a casting model of a second embodiment;

[0031] Figure 8 Schematic diagram of the second embodiment of the split ring welding anti-deformation reinforcement;

[0032] Figure numerals: 1-petal ring; 2-casting model; 3-petal ring body; 4-shrinkage compensation system; 5-connecting ribs; 6-casting pouring system; 7-first transverse ribs; 8-second transverse ribs; 9-longitudinal ribs; 10-transition section. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] like Figure 1-Figure 8 As shown, the present invention provides a method for manufacturing a large-scale ring-type steel casting petal ring, comprising the following steps:

[0035] S1: Design a casting model 2, the casting model 2 includes at least two petal ring bodies 3, each of the petal ring bodies 3 is provided with a shrinkage compensation system 4, the shrinkage compensation system 4 includes a riser, inner and outer circular surfaces of the petal ring body 3, end surface processing amount and casting correction amount; it should be noted here that a plurality of petal ring bodies 3 can form a rotating wheel, if there are two petal ring bodies 3, the corresponding central angle of each petal ring body 3 is 180°, if there are three petal ring bodies 3, the corresponding central angle of each petal ring body 3 is 120°. The cavity of the riser is a cavity for storing liquid metal, which supplies metal when the casting is formed, and has the function of preventing shrinkage cavities, shrinkage, exhaust and slag collection. The number, size and spacing of the risers are set according to actual conditions.

[0036] S2: Two adjacent petal ring bodies 3 are connected by connecting ribs 5, which are arranged along the axial direction of the petal ring body 3, and the thickness of the connecting ribs 5 is 50% to 70% of the wall thickness at the corresponding position of the petal ring body 3; the connecting ribs 5 are arranged on the side of the petal ring 1, extending from the top of the side of the petal ring 1 to the bottom, and the outer surface of the connecting ribs 5 is coplanar with the outer surface of the petal ring body 3, and the thickness of the connecting ribs 5 is 50% to 70% of the wall thickness at the corresponding position of the petal ring body 3, so that the position of the connecting ribs 5 can be better found when the connecting ribs 5 are cut later, and the amount of molten steel used can also be reduced. The setting of the connecting ribs 5 can not only meet the cutting amount during the splitting and the end surface machining allowance of the petal ring 1 after the subsequent cutting is completed, but also constrain multiple petal rings 1 into a whole during the subsequent casting and processing process, which increases the rigidity, can greatly reduce the stress deformation of the product during the manufacturing process, and at the same time, the heat treatment furnace loading is also simpler and faster.

[0037] S3: Setting up a casting pouring system 6, wherein the casting pouring system 6 includes a straight runner, a ring runner, an inner runner, a distribution position, a quantity and a runner cross-sectional size;

[0038] S4: a sand mold cavity is made according to the shape and size of the casting model 2 and the casting pouring system 6, and qualified molten steel is poured in and cooled along with the molding sand, and after the pit is cooled to the temperature, the pit is boxed out to obtain the integral casting;

[0039] S5: removing the feeding system 4 and the casting pouring system 6 from the integral casting to obtain a full-ring casting; that is, removing the sprue, the ring runner, the ingates, the risers, etc.

[0040] S6: The whole ring casting is put into the furnace for heat treatment, wherein the heat treatment is normalizing and tempering; when the whole ring casting is put into the furnace, the axis of the whole ring casting is vertical, and the normalizing treatment refines the crystal grains of the whole ring casting, improves the strength of the whole ring casting, and can significantly improve the toughness (AKV value), and reduce the cracking tendency of the whole ring casting. The tempering treatment reduces the internal stress in the whole ring casting and improves the ductility of the whole ring casting.

[0041] S7: The whole ring casting that has passed the S6 heat treatment is cut along the center line of the connecting rib 5 to split the whole ring casting into petal rings 1, and the connecting rib 5 is removed. The cutting of the connecting rib 5 can be done by flame cutting or mechanical processing, and then the redundant connecting rib 5 is removed by grinding.

[0042] Further, in step S2, the width of the connecting rib 5 is 50 mm to 100 mm. With this arrangement, the center line of the connecting rib 5 can be better found during cutting, which facilitates cutting.

[0043] Further, in step S6, the normalizing is to heat the whole ring casting to 100°C to 250°C above the Ac3 point of the material, keep it warm and then cool it quickly; the tempering is to heat the whole ring casting to 20°C to 30°C above the Ac1 point of the material, keep it warm and then cool it slowly; the normalizing and tempering temperature holding time is calculated according to the hot node diameter at the thickest position of the whole ring casting, and the insulation time is 3h to 5h for every 100mm.

[0044] Since the processing amount and casting correction amount of the inner and outer circular surfaces and the end surfaces are set in the design process of the casting model 2, the surface of the petal ring 1 needs to be processed after the casting is completed. Furthermore, after step S7, the following steps are also included: S8: the inner and outer circular surfaces and the upper and lower end surfaces of the petal ring 1 described in S7 are machined, and the corresponding quality inspection and quality repair are performed; S9: the petal ring 1 that has been processed qualifiedly in S8 is welded with anti-deformation tie rods on the inner surface of the petal ring 1. Welding anti-deformation tie rods in the petal ring 1 can prevent the petal ring 1 that has been processed qualifiedly from being deformed during transportation.

[0045] As an embodiment, further, the anti-deformation reinforcement includes at least two first transverse ribs 7 arranged at intervals along the axial direction of the petal ring 1, and the number of the first transverse ribs 7 is determined according to the height of the petal ring 1, and a first transverse rib 7 is arranged at every 800mm to 1000mm height. The first transverse rib 7 connects the two radial ends of the inner surface of the petal ring 1, and a second transverse rib 8 is arranged between the first transverse rib 7 and the inner surface of the petal ring 1. The second transverse rib 8 is perpendicular to the first transverse rib 7, one end of the second transverse rib 8 is connected to the first transverse rib 7, and the other end is connected to the inner surface of the petal ring 1. Two adjacent first transverse ribs 7 are connected by longitudinal ribs 9, and the number of longitudinal ribs 9 can be multiple to improve the stability of the anti-deformation reinforcement.

[0046] Furthermore, the first transverse reinforcement 7, the second transverse reinforcement 8 and the longitudinal reinforcement 9 are rails or channel steels made of low carbon equivalent materials. To ensure the rigidity of the first transverse reinforcement 7, the second transverse reinforcement 8 and the longitudinal reinforcement 9, the effective cross-sectional area of ​​the first transverse reinforcement 7, the second transverse reinforcement 8 and the longitudinal reinforcement 9 is 3000-5000mm. 2 .

[0047] In order to prevent the first transverse rib 7, the second transverse rib 8 and the petal ring 1 from being contaminated when being welded, further, a transition section 10 made of the same material as the petal ring 1 is provided at the connection between the first transverse rib 7 and the petal ring 1 and at the connection between the second transverse rib 8 and the petal ring 1, and the length of the transition section 10 is 70 to 80 mm.

[0048] Embodiment 1:

[0049] The diameter of the power wheel of a BHT project hydropower station in the Jinsha River Basin is 7.8 meters and the height is 1.8 meters. The cross-sectional thickness is about 180mm to 280mm. Due to the narrow transportation road, the castings cannot be transported to the power station site. The main engine manufacturer of the turbine requires the manufacturer to divide the wheel into two petal rings 1 for supply. See the schematic diagram Figure 1 .

[0050] The product manufacturing steps are as follows (see Figure 2-Figure 4 ):

[0051] S1: Design a casting model 2, the casting model 2 comprising two petal ring bodies 3, each of the petal ring bodies 3 being provided with a shrinkage compensation system 4, the shrinkage compensation system 4 comprising a riser, inner and outer circumferential surfaces of the petal ring body 3, and end surface design processing amounts and casting correction amounts;

[0052] S2: The two petal ring bodies 3 are connected by connecting ribs 5, which are arranged along the axial direction of the petal ring body 3. The thickness of the connecting ribs 5 is 50% of the wall thickness at the corresponding position of the petal ring body 3. The width should meet the cutting amount and processing allowance during the later splitting, and the width is about 50mm.

[0053] S3: Setting up a casting pouring system 6, wherein the casting pouring system 6 includes a straight runner, a ring runner, an inner runner, a distribution position, a quantity and a runner cross-sectional size;

[0054] S4: a sand mold cavity is made according to the shape and size of the casting model 2 and the casting pouring system 6, and qualified molten steel is poured in and cooled along with the molding sand, and after the pit is cooled to the temperature, the pit is boxed out to obtain the integral casting;

[0055] S5: removing the shrinkage feeding system 4 and the casting pouring system 6 from the integral casting to obtain a complete ring casting;

[0056] S6: Place the whole ring casting into a furnace for heat treatment, wherein the heat treatment is normalizing and tempering; the normalizing and tempering process is: slowly heat until the workpiece temperature reaches 1040±10°C and maintain for 10 hours, quickly cool after taking out of the furnace, with a cooling rate of 1°C / s, and when the product cools to <100°C, enter the heat treatment furnace, heat until the workpiece temperature reaches 600±10°C and maintain for 12 hours, then slowly cool, with a slow cooling rate of 20°C / min.

[0057] S7: The whole ring casting that has passed the S6 heat treatment is cut along the center line of the connecting rib 5 by flame cutting or mechanical processing to split the whole ring casting into two petal rings 1, and the connecting rib 5 is removed by grinding.

[0058] S8: The inner and outer circular surfaces and the upper and lower end surfaces of the petal ring 1 are machined according to the size requirements of the drawing, and corresponding quality inspections and necessary quality repairs are performed.

[0059] S9: Weld anti-deformation reinforcement on the inner surface of the petal ring 1 after the qualified treatment described in S8. The anti-deformation reinforcement includes at least two first transverse reinforcements 7 arranged at intervals along the axial direction of the petal ring 1, the first transverse reinforcement 7 connecting the two radial ends of the inner surface of the petal ring 1, and a second transverse reinforcement 8 is arranged between the first transverse reinforcement 7 and the inner surface of the petal ring 1. The second transverse reinforcement 8 is perpendicular to the first transverse reinforcement 7, one end of the second transverse reinforcement 8 is connected to the first transverse reinforcement 7, and the other end is connected to the inner surface of the petal ring 1, and two adjacent first transverse reinforcements 7 are connected by a longitudinal reinforcement 9. The material of the first transverse reinforcement 7, the second transverse reinforcement 8 and the longitudinal reinforcement 9 is Q345 channel steel, and the effective cross-sectional area of ​​the channel steel is 3000mm 2 Each layer of the first transverse rib 7 is connected with two longitudinal ribs 9. The material of the petal ring 1 is martensitic stainless steel. To prevent ferrite contamination, the connection between the first transverse rib 7 and the petal ring 1 and the connection between the second transverse rib 8 and the petal ring 1 are provided with a transition section 10 made of the same material as the petal ring 1. The length of the transition section 10 is about 70 mm.

[0060] Embodiment 2:

[0061] In a hydropower station of a WDD project in the Jinsha River Basin, the diameter of the petal ring 1 in the power generation wheel reaches 9.9 meters and the height is 2.5 meters. The cross-sectional thickness is about 100mm to 180mm. Due to the narrow transportation road, the castings cannot be transported to the power station site. The main engine manufacturer of the turbine requires the manufacturer to divide the wheel into three petal rings 1 for supply. See the schematic diagram Figure 5 .

[0062] The petal ring 1 is made of ZG04Cr13Ni4Mo martensitic stainless steel, has a special-shaped curved surface, and has an uneven wall thickness.

[0063] The product manufacturing steps are as follows (see Figure 6-Figure 8 ):

[0064] S1: Design a casting model 2, the casting model 2 comprising two petal ring bodies 3, each of the petal ring bodies 3 being provided with a shrinkage compensation system 4, the shrinkage compensation system 4 comprising a riser, inner and outer circumferential surfaces of the petal ring body 3, and end surface design processing amounts and casting correction amounts;

[0065] S2: The two petal ring bodies 3 are connected by connecting ribs 5, which are arranged along the axial direction of the petal ring body 3. The thickness of the connecting ribs 5 is 70% of the wall thickness at the corresponding position of the petal ring body 3. The width should meet the cutting amount and processing allowance during the later splitting, and the width is about 100mm.

[0066] S3: Setting up a casting pouring system 6, wherein the casting pouring system 6 includes a straight runner, a ring runner, an inner runner, a distribution position, a quantity and a runner cross-sectional size;

[0067] S4: a sand mold cavity is made according to the shape and size of the casting model 2 and the casting pouring system 6, and qualified molten steel is poured in and cooled along with the molding sand, and after the pit is cooled to the temperature, the pit is boxed out to obtain the integral casting;

[0068] S5: removing the shrinkage feeding system 4 and the casting pouring system 6 from the integral casting to obtain a complete ring casting;

[0069] S6: Place the whole ring casting into a furnace for heat treatment, wherein the heat treatment is normalizing and tempering; the normalizing and tempering process is: slowly heat until the workpiece temperature reaches 1040±10°C and maintain for 10 hours, then quickly cool down after being taken out of the furnace, with a cooling rate of 1°C / s; when the product cools to <100°C, enter the heat treatment furnace, heat until the workpiece temperature reaches 600±10°C and maintain for 12 hours, then slowly cool, with a slow cooling rate of 20°C / min.

[0070] S7: The whole ring casting that has passed the S6 heat treatment is cut along the center line of the connecting rib 5 by flame cutting or mechanical processing to split the whole ring casting into two petal rings 1, and the connecting rib 5 is removed by grinding.

[0071] S8: The inner and outer circular surfaces and the upper and lower end surfaces of the petal ring 1 are machined according to the size requirements of the drawing, and corresponding quality inspections and necessary quality repairs are performed.

[0072] S9: Weld anti-deformation reinforcement on the inner surface of the petal ring 1 after the qualified treatment described in S8. The anti-deformation reinforcement includes at least two first transverse reinforcements 7 arranged at intervals along the axial direction of the petal ring 1, the first transverse reinforcement 7 connecting the two radial ends of the inner surface of the petal ring 1, and a second transverse reinforcement 8 is arranged between the first transverse reinforcement 7 and the inner surface of the petal ring 1. The second transverse reinforcement 8 is perpendicular to the first transverse reinforcement 7, one end of the second transverse reinforcement 8 is connected to the first transverse reinforcement 7, and the other end is connected to the inner surface of the petal ring 1, and two adjacent first transverse reinforcements 7 are connected by a longitudinal reinforcement 9. The material of the first transverse reinforcement 7, the second transverse reinforcement 8 and the longitudinal reinforcement 9 is Q345 channel steel, and the effective cross-sectional area of ​​the channel steel is 5000mm 2 Each layer of the first transverse rib 7 is connected with two longitudinal ribs 9. The material of the petal ring 1 is martensitic stainless steel. To prevent ferrite contamination, the connection between the first transverse rib 7 and the petal ring 1 and the connection between the second transverse rib 8 and the petal ring 1 are provided with a transition section 10 made of the same material as the petal ring 1. The length of the transition section 10 is about 80 mm.

[0073] The embodiments of this specific implementation method are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a large ring-type steel casting split ring, characterized in that: The following steps are included: S1: Designing a casting model (2), the casting model (2) comprising at least two petal ring bodies (3), each of the petal ring bodies (3) being provided with a shrinkage compensation system (4), the shrinkage compensation system (4) comprising a riser, inner and outer circumferential surfaces of the petal ring body (3), and end surface design processing amounts and casting correction amounts; S2: Two adjacent petal ring bodies (3) are connected by a connecting rib (5), the connecting rib (5) is arranged along the axial direction of the petal ring body (3), and the thickness of the connecting rib (5) is 50% to 70% of the wall thickness of the corresponding position of the petal ring body (3); S3: Setting up a casting pouring system (6), wherein the casting pouring system (6) includes a straight runner, a ring runner, an inner runner, a distribution position, a quantity and a runner cross-sectional size; S4: a sand mold cavity is made according to the shape and size of the casting model (2) and the casting pouring system (6), and qualified molten steel is poured in and cooled along with the molding sand. After the pit is cooled to the temperature, the pit is boxed and the integral casting is obtained; S5: removing the shrinkage feeding system (4) and the casting pouring system (6) from the integral casting to obtain a complete ring casting; S6: placing the whole ring casting into a furnace for heat treatment, wherein the heat treatment includes normalizing and tempering; S7: The whole ring casting that has passed the S6 heat treatment is cut along the center line of the connecting rib (5) to split the whole ring casting into petal rings (1), and the connecting rib (5) is removed.

2. The method for manufacturing a large-scale ring-type steel casting petal ring according to claim 1, characterized in that: In step S2, the width of the connecting rib (5) is 50 mm to 100 mm.

3. The method for manufacturing a large-scale ring-like steel casting petal ring according to claim 1, characterized in that: In step S6, the normalizing is to heat the whole ring casting to 100°C to 250°C above the Ac3 point of the material, keep it warm and then cool it quickly; the tempering is to heat the whole ring casting to 20°C to 30°C above the Ac1 point of the material, keep it warm and then cool it slowly; the normalizing and tempering temperature holding time is calculated according to the hot node diameter at the thickest position of the whole ring casting, and the insulation time is 3h to 5h for every 100mm.

4. The method for manufacturing a large-scale ring-like steel casting petal ring according to claim 1, characterized in that: After step S7, the following steps are also included: S8: Mechanically process the inner and outer circular surfaces and the upper and lower end surfaces of the petal ring (1) described in S7, and perform corresponding quality inspection and quality repair; S9: Welding anti-deformation reinforcement bars on the inner surface of the petal ring (1) that has passed the treatment in S8.

5. The method for manufacturing a large-scale ring-type steel casting petal ring according to claim 4, characterized in that: The anti-deformation reinforcement comprises at least two first transverse ribs (7) arranged at intervals along the axial direction of the petal ring (1), the first transverse rib (7) connecting the two radial ends of the inner surface of the petal ring (1), a second transverse rib (8) is arranged between the first transverse rib (7) and the inner surface of the petal ring (1), the second transverse rib (8) is perpendicular to the first transverse rib (7), one end of the second transverse rib (8) is connected to the first transverse rib (7), and the other end is connected to the inner surface of the petal ring (1), and two adjacent first transverse ribs (7) are connected by a longitudinal rib (9).

6. The method for manufacturing a large-scale ring-like steel casting petal ring according to claim 5, characterized in that: The number of the first transverse ribs (7) is determined according to the height of the petal ring (1), and one first transverse rib (7) is provided for every 800 mm to 1000 mm of height.

7. The method for manufacturing a large-scale ring-like steel casting petal ring according to claim 5, characterized in that: The first transverse reinforcement (7), the second transverse reinforcement (8) and the longitudinal reinforcement (9) are rails or channel steels made of low carbon equivalent materials, and the effective cross-sectional areas of the first transverse reinforcement (7), the second transverse reinforcement (8) and the longitudinal reinforcement (9) are 3000 to 5000 mm 2 .

8. The method for manufacturing a large-scale ring-like steel casting petal ring according to claim 5, characterized in that: A transition section (10) made of the same material as the petal ring (1) is provided at the connection between the first transverse rib (7) and the petal ring (1) and at the connection between the second transverse rib (8) and the petal ring (1).

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