Steel ring forging process

Abstract

The invention relates to the technical field of metal material processing, in particular to a steel ring forging process which comprises the following steps: S1, heating a steel ingot to an initial forging temperature of 1150-1250 DEG C; s2, a wide flat anvil high-temperature forced pressing method is adopted, the anvil width ratio is 0.6-0.8, and the reduction rate is 20%; s3, a pre-hole with the diameter being 1 / 3-1 / 2 of the diameter of the steel ingot is formed in the center of the forged steel ingot through a punching technology; s4, a ring rolling mill is adopted for chambering, and the ring rolling ratio of a driving roller to a core roller is 2.5-3.0; s5, through a multi-pass rolling process, the outer diameter of the steel ring reaches the designed size; s6, an air cooling or fog cooling mode is adopted, and the cooling rate is controlled to be 50-80 DEG C / h; and S7, deburring, surface polishing and dimensional precision inspection are included. The technical problems that in the forging and pressing process of an existing steel ring, internal cracks and residual stress are likely to be generated in a steel ingot, and the size precision of the steel ring is likely to be low in the rolling broaching and forming process are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material processing, in particular to a steel ring forging process. Background Art

[0002] Currently, steel rim forging is a key branch of mechanical manufacturing, widely used in industries such as automotive, aviation, aerospace, and energy. As a key component, the quality and performance of steel rims directly impact the operational stability and safety of the entire mechanical system. Therefore, improving the quality of steel rim forging has always been a key focus of technical research and development in this field.

[0003] The steel rim forging process involves multiple steps, including heating, forging, punching, roll-forming, cooling, and subsequent processing. The process parameters and operating conditions of each step significantly impact the quality of the final steel rim. While existing steel rim forging technology has made some progress, some defects and shortcomings still exist in actual production, making it difficult to further improve the quality of steel rim forging. The main drawbacks of existing steel rim forging technology are:

[0004] 1. During the forging process, improper control of the reduction amount and reduction rate may cause uneven deformation of the steel ingot, resulting in internal cracks or residual stress, affecting the mechanical properties of the steel ring;

[0005] 2. During the roller expansion and forming process, unreasonable control of parameters such as the rolling ratio, feed speed, and rolling temperature may lead to problems such as low steel ring size accuracy and large ovality error. Summary of the Invention

[0006] Therefore, in response to the above problems, the present invention proposes a steel ring forging process, which solves the technical problems that the existing steel rings are prone to cause internal cracks and residual stress in the steel ingot during the forging process, and are prone to low dimensional accuracy of the steel rings during roller expansion and forming.

[0007] To achieve the above object, the present invention adopts the following technical solution: a steel ring forging process, comprising the following steps:

[0008] S1. Ingot heating: Heat the ingot to the initial forging temperature of 1150℃~1250℃. The holding time is calculated based on the weight of the ingot at 1.5 hours / ton, ensuring the temperature uniformity of ±10℃;

[0009] S2. Ingot forging: adopt wide flat anvil high temperature strong pressing method, anvil width ratio 0.6-0.8, pressing rate 20%, single pressing amount does not exceed 30% of the ingot height;

[0010] S3. Ingot punching: A pre-hole with a diameter of 1 / 3 to 1 / 2 of the ingot diameter is formed in the center of the forged ingot through a punching process;

[0011] S4. Ring Rolling Expansion: Ring rolling mill is used for hole expansion, with the expansion ratio of the driving roller to the core roller being 2.5-3.0, the feed speed being 8-15 mm / s, and the rolling temperature being controlled at 1050-1100°C.

[0012] S5. Steel ring roll forming: Through multiple roll forming processes, the outer diameter of the steel ring reaches the designed size, the deformation of a single pass does not exceed 15%, and the total deformation is ≥ 60%;

[0013] S6. Steel ring cooling: Use air cooling or mist cooling, and control the cooling rate at 50℃ / h~80℃ / h to avoid surface cracks;

[0014] S7. Subsequent processing: including deburring, surface polishing and dimensional accuracy inspection.

[0015] Furthermore, in the steel ingot heating step, when the initial temperature of the steel ingot is ≥600°C, a hot delivery process is adopted, and the holding time is shortened by 20%; when the initial temperature of the steel ingot is <600°C, a cold delivery process is adopted, and the holding time is increased by 15%.

[0016] Furthermore, in the steel ingot forging step, a two-pressing process is adopted, and a 10% anvil width overlap is retained between the two pressing parts. When flipping and pressing, the anvil angle is ≥30° to ensure uniform compaction of the billet.

[0017] Furthermore, in the steel ring rolling and expanding step, the ratio of the drive roller radius to the core roller radius (R+r) / (Rr) is 2.5-3.0, the rolling line speed is controlled at 1.5-2.0 m / s, and the ring wall thickness thinning rate is ≥40%.

[0018] Furthermore, in the steel ring roll forming step, a rolling process with synchronous control of radial and axial directions is adopted, the ratio of axial feed to radial feed is 1:2 to 1:3, and the ring ovality error is ≤0.5mm.

[0019] Furthermore, in the steel ring rolling and expanding step, the initial height-to-thickness ratio of the ring is ≤6:1. When the height-to-thickness ratio exceeds 6:1, a pre-rolling groove process is adopted, and the groove depth is 10% to 15% of the wall thickness, and the width is 20% to 25% of the wall thickness.

[0020] Furthermore, in the steel ring cooling step, when the steel ring wall thickness is ≥50 mm, a graded cooling process is adopted, and the specific steps are as follows:

[0021] S61, mist cooling stage: place the steel ring in a mist cooling environment, and control the cooling rate at 60℃ / h~80℃ / h until the surface temperature of the steel ring drops to 800℃;

[0022] S62, air cooling stage: transfer the steel ring to an air cooling environment, and control the cooling rate at 40℃ / h~60℃ / h until the surface temperature of the steel ring drops to 400℃;

[0023] S63, slow cooling stage: placing the steel ring in a heat preservation environment, and controlling the cooling rate at 10℃ / h~20℃ / h until the surface temperature of the steel ring drops to room temperature;

[0024] When the wall thickness of the steel ring is less than 50mm, a continuous air cooling process is adopted and the cooling rate is controlled at 50℃ / h~80℃ / h to avoid surface cracks.

[0025] Furthermore, the slow cooling stage includes the following steps:

[0026] S631, Insulation: Place the steel ring in an insulation device with temperature monitoring and automatic adjustment functions. The device can adjust the heating power according to the real-time temperature of the steel ring to ensure a stable cooling rate;

[0027] S632, cooling rate control: the cooling rate is controlled within the range of 8°C / h to 15°C / h in the range of 400°C to 300°C; the cooling rate is controlled within the range of 5°C / h to 10°C / h in the range of 300°C to 200°C; the cooling rate is controlled within the range of 3°C / h to 8°C / h in the range of 200°C to room temperature;

[0028] S633, Ambient atmosphere control: During the slow cooling stage, inert gas is filled into the insulation device to reduce oxidation on the surface of the steel ring. At the same time, the humidity in the device is controlled to avoid cracks on the surface of the steel ring due to humidity changes.

[0029] Furthermore, the slow cooling stage also includes the following steps:

[0030] S634, vibration treatment: During the slow cooling process, the steel ring can be subjected to low-frequency vibration treatment, with the vibration frequency controlled at 50Hz~100Hz and the amplitude controlled at 0.1mm~0.5mm, to promote the release of internal stress of the steel ring and reduce residual stress.

[0031] Furthermore, in the environmental atmosphere control step, the inert gas charged is nitrogen, and the oxygen concentration is maintained at 1-5%;

[0032] High-frequency and small-amplitude vibration is used in the temperature range of 400℃-300℃, and low-frequency and large-amplitude vibration is used when the temperature is less than 300℃, and the vibration adopts pulse intermittent vibration.

[0033] By adopting the above technical solution, the beneficial effects of the present invention are:

[0034] 1. By precisely controlling the steel ingot heating temperature, holding time, forging parameters, punching process, roll expansion and forming parameters, cooling rate, and subsequent processing steps, the quality of steel ring forging can be significantly improved. This process ensures high dimensional accuracy, uniform structure, and excellent mechanical properties of the steel ring. It also effectively reduces surface cracks and internal residual stress, thereby increasing product qualification rate and service life.

[0035] 2. Flexibly adjusting the hot or cold delivery process based on the initial ingot temperature and shortening or increasing the holding time accordingly can improve production efficiency and reduce energy consumption. This adjustment ensures temperature uniformity during the heating process, avoiding local overheating or underheating, and laying a good foundation for subsequent forging steps.

[0036] 3. Using a double-pressing process while maintaining the anvil width overlap and staggered anvil angle ensures uniform compaction of the billet, reducing internal cracks and residual stress. This process improves the forging quality of the steel ring, resulting in a denser internal structure and superior mechanical properties.

[0037] 4. By precisely controlling the rolling ratio between the drive and core rollers, the rolling line speed, and the ring wall thickness reduction rate, the steel ring roll expansion process can be optimized, improving dimensional accuracy and forming quality. This process reduces cracks and defects during expansion, enhancing the surface quality and mechanical properties of the steel ring.

[0038] 5. A rolling process that utilizes synchronous radial and axial control, while precisely controlling the ratio of axial to radial feed, effectively reduces ovality errors during the steel ring roll-forming process. This process improves the dimensional accuracy and appearance quality of the steel ring, meeting the requirements of high-precision applications.

[0039] 6. For rings with a high thickness ratio exceeding 6:1, the pre-rolling groove process can effectively reduce cracks and defects during the hole expansion process. This process improves the forming quality and mechanical properties of the steel ring while reducing material waste and production costs.

[0040] 7. Flexible use of graded cooling or continuous air cooling processes based on the steel ring wall thickness and precise control of the cooling rate effectively avoids surface cracks and internal structural unevenness. This process improves the cooling quality and mechanical properties of the steel ring while reducing deformation and cracking during the cooling process.

[0041] 8. During the slow cooling phase, a heat preservation device, temperature monitoring, and automatic adjustment functions are used to ensure a stable cooling rate, reducing internal stress and cracking. This process improves the cooling quality and mechanical properties of the steel ring, while also reducing the defective product rate during the production process.

[0042] 9. Low-frequency vibration treatment of the steel ring during the slow cooling process can promote the release of internal stress in the steel ring and reduce residual stress. This process improves the mechanical performance and service life of the steel ring, while reducing cracks and fractures caused by stress concentration during use.

[0043] 10. During the atmosphere control step, nitrogen and other inert gases are introduced, and oxygen concentration and humidity are controlled to reduce surface oxidation and cracking caused by humidity fluctuations. This process improves the surface quality and corrosion resistance of the steel rims, while also extending their service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a process flow diagram of the present invention.

[0045] Figure 2 It is a schematic diagram of the graded cooling process flow.

[0046] Figure 3 It is a process flow diagram of the slow cooling stage.

[0047] Figure 4 It is a structural schematic diagram of the present invention.

[0048] Figure 5 yes Figure 4 Schematic diagram of the structure of the middle support mechanism cooperating with the second roller part.

[0049] Figure 6 It is a structural diagram of the support component and the metal ring.

[0050] Figure 7 yes Figure 5 Enlarged view of point A in the middle.

[0051] Reference numerals:

[0052] 1. Frame; 2. Sliding seat; 21. Pushing cylinder; 3. Rolling mechanism; 33. Rotating motor; 31. First rolling part; 32. Second rolling part; 4. Support roller body; 41. First roller part; 42. Second roller part; 43. Transition arc surface; 51. Support plate; 52. Swing drive device; 511. Recessed part; 512. Flexible buffer layer; 513. Wear-resistant material layer; 61. Lifting cylinder; 62. Lifting plate; 71. Supporting cylinder; 72. Pressing roller; 73. Rotating cylinder; 9. Metal ring. DETAILED DESCRIPTION

[0053] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0054] refer to Figures 1 to 3 This embodiment provides a steel ring forging process, comprising the following steps:

[0055] S1. Ingot heating: Heat the ingot to the initial forging temperature of 1150℃~1250℃. The holding time is calculated based on the weight of the ingot at 1.5 hours / ton, ensuring the temperature uniformity of ±10℃;

[0056] S2. Ingot forging: adopt wide flat anvil high temperature strong pressing method, anvil width ratio 0.6-0.8, pressing rate 20%, single pressing amount does not exceed 30% of the ingot height;

[0057] S3. Ingot punching: A pre-hole with a diameter of 1 / 3 to 1 / 2 of the ingot diameter is formed in the center of the forged ingot through a punching process;

[0058] S4. Ring Rolling Expansion: Ring rolling mill is used for hole expansion, with the expansion ratio of the driving roller to the core roller being 2.5-3.0, the feed speed being 8-15 mm / s, and the rolling temperature being controlled at 1050-1100°C.

[0059] S5. Steel ring roll forming: Through multiple roll forming processes, the outer diameter of the steel ring reaches the designed size, the deformation of a single pass does not exceed 15%, and the total deformation is ≥ 60%;

[0060] S6. Steel ring cooling: Use air cooling or mist cooling, and control the cooling rate at 50℃ / h~80℃ / h to avoid surface cracks;

[0061] S7. Subsequent processing: including deburring, surface polishing and dimensional accuracy inspection.

[0062] In the steel ingot heating step, when the initial temperature of the steel ingot is ≥600°C, a hot delivery process is adopted, and the holding time is shortened by 20%; when the initial temperature of the steel ingot is <600°C, a cold delivery process is adopted, and the holding time is increased by 15%.

[0063] In the steel ingot forging step, a two-pressing process is adopted, and a 10% anvil width overlap is retained between the two pressing parts. When turning and pressing, the anvil angle is ≥30° to ensure uniform compaction of the billet.

[0064] In the steel ring rolling and expanding step, the ratio of the driving roller radius to the core roller radius (R+r) / (Rr) is 2.5-3.0, R represents the driving roller radius, r represents the core roller radius, the rolling line speed is controlled at 1.5-2.0 m / s, and the ring wall thickness thinning rate is ≥40%.

[0065] In the steel ring rolling and expanding step, the initial height-to-thickness ratio of the ring is ≤6:1. When the height-to-thickness ratio exceeds 6:1, a pre-rolling groove process is adopted, and the groove depth is 10% to 15% of the wall thickness and the width is 20% to 25% of the wall thickness.

[0066] In the steel ring roll forming step, a rolling process with synchronous radial and axial control is adopted, the ratio of axial feed to radial feed is 1:2 to 1:3, and the ring ovality error is ≤0.5mm.

[0067] In the steel ring cooling step, when the steel ring wall thickness is ≥50mm, a graded cooling process is adopted, and the specific steps are as follows:

[0068] S61, mist cooling stage: place the steel ring in a mist cooling environment, and control the cooling rate at 60℃ / h~80℃ / h until the surface temperature of the steel ring drops to 800℃;

[0069] S62, air cooling stage: transfer the steel ring to an air cooling environment, and control the cooling rate at 40℃ / h~60℃ / h until the surface temperature of the steel ring drops to 400℃;

[0070] S63, slow cooling stage: placing the steel ring in a heat preservation environment, and controlling the cooling rate at 10℃ / h~20℃ / h until the surface temperature of the steel ring drops to room temperature;

[0071] When the wall thickness of the steel ring is less than 50mm, a continuous air cooling process is adopted and the cooling rate is controlled at 50℃ / h~80℃ / h to avoid surface cracks.

[0072] Of course, all stages of the fan cooling process can also use mist cooling or air cooling.

[0073] The slow cooling stage includes the following steps:

[0074] S631, Insulation: Place the steel ring in an insulation device with temperature monitoring and automatic adjustment functions. The device can adjust the heating power according to the real-time temperature of the steel ring to ensure a stable cooling rate;

[0075] S632, cooling rate control: the cooling rate is controlled within the range of 8°C / h to 15°C / h in the range of 400°C to 300°C; the cooling rate is controlled within the range of 5°C / h to 10°C / h in the range of 300°C to 200°C; the cooling rate is controlled within the range of 3°C / h to 8°C / h in the range of 200°C to room temperature;

[0076] S633, Ambient atmosphere control: During the slow cooling stage, inert gas is filled into the insulation device to reduce oxidation on the surface of the steel ring. At the same time, the humidity in the device is controlled to avoid cracks on the surface of the steel ring due to humidity changes.

[0077] S634, vibration treatment: During the slow cooling process, the steel ring can be subjected to low-frequency vibration treatment, with the vibration frequency controlled at 50Hz~100Hz and the amplitude controlled at 0.1mm~0.5mm, to promote the release of internal stress of the steel ring and reduce residual stress.

[0078] The insulation device is equipped with high-precision temperature sensors located at key locations around the steel ring and within the device. These sensors accurately monitor the temperature of the steel ring and the ambient temperature within the device in real time. The temperature sensors transmit the collected temperature data to the central control system for subsequent analysis and processing. The insulation device is equipped with heating elements, such as electric heating wires or infrared heaters, which provide heat when needed to maintain a stable temperature within the device. Based on the data transmitted by the temperature sensors, the central control system automatically adjusts the power of the heating elements to control the temperature within the device. When the temperature falls below the set point, the control system increases the power of the heating elements; when the temperature rises above the set point, the control system reduces the power of the heating elements or stops heating.

[0079] During the atmosphere control step, nitrogen is used as an inert gas, maintaining an oxygen concentration of 1-5%. High-frequency, low-amplitude vibration is employed in the 400°C-300°C range, while low-frequency, high-amplitude vibration is used below 300°C. Pulsed intermittent vibration is employed. Introducing nitrogen and other inert gases during the atmosphere control step, while controlling oxygen concentration and humidity, reduces surface oxidation and cracking caused by humidity fluctuations in the steel rings. This process improves the surface quality and corrosion resistance of the steel rings, while also extending their service life. High-frequency, low-amplitude vibration in the higher temperature range promotes rapid stress release within the steel rings, while preventing surface damage or internal cracking caused by excessive vibration amplitude. Low-frequency, high-amplitude vibration in the lower temperature range further promotes stress release within the steel rings, while reducing energy loss and equipment wear caused by excessive vibration frequency. Pulsed intermittent vibration effectively controls the input of vibration energy, preventing internal stress concentration or excessive release caused by continuous vibration, thereby improving the vibration treatment effect and the overall quality of the steel rings. The surface quality and internal structural uniformity of the steel ring are improved, thereby reducing the risk of cracks and fractures caused by stress concentration or surface damage during use.

[0080] During the steel ring roll forming step, a closed-loop proportional control system is used to monitor the outer diameter of the ring in real time, automatically adjust the rolling force, and control the outer diameter tolerance within ±1mm.

[0081] The steel ring forging process is applicable to carbon steel, alloy steel and stainless steel materials, wherein the rolling temperature of carbon steel is 1100°C to 1150°C, the rolling temperature of alloy steel is 1150°C to 1200°C, and the rolling temperature of stainless steel is 1200°C to 1250°C.

[0082] In the steel ring forging process, during the steel ring roller expansion and forming process, an induction heating furnace can be used to provide real-time temperature compensation to ensure that the ring temperature is higher than the material recrystallization temperature and avoid work hardening.

[0083] In addition, in the steel ring roll forming of step S5, a double-station ring rolling machine is used to achieve the steel ring roll forming. Figures 4 to 7 As shown, a double-station ring rolling machine is used for rolling and expanding a metal ring body 9, comprising a frame 1 and a sliding seat 2 that can slide up and down along the frame 1, a pushing cylinder 21 provided on the frame 1 to drive the sliding seat 2, a rolling mechanism 3 rotatably provided on the sliding seat 2, a rotating motor 33 that drives the rolling mechanism 3 to rotate, and a supporting roller body 4 rotatably provided on the frame 1 and located below the rolling mechanism 3, the supporting roller body 4 is used to support the ring body and cooperate with the rolling mechanism 3 to achieve rolling expansion, the frame 1 is in an inclined state, and the inclination angle β is 5-30 degrees, so that the supporting roller body 4 can achieve independent support for the metal ring body 9, the supporting roller body 4 is close to the first roller portion 41 of the frame 1 and the second roller portion 42 located outside the first roller portion 41, the diameter of the second roller portion 42 is smaller than the diameter of the first roller portion 41, and the rolling mechanism 3 includes a first rolling portion 31 cooperating with the first roller portion 41 and a second rolling portion 32 cooperating with the second roller portion 42.

[0084] The tilt angle β is preferably 10 degrees, which ensures independent support while also facilitating operation and observation.

[0085] The frame 1 is provided with a support mechanism for supporting the second roller portion 42. The support mechanism is rotatably mounted on a support plate 51 on the frame 1 and includes a swing drive device 52 that drives the support plate 51 toward or away from the second roller portion 42. The support plate 51 is provided with a recessed portion 511 that engages with the free end of the second roller portion 42. The swing drive device 52 is a hydraulic cylinder.

[0086] The shape of the recessed portion 511 is an arc that matches the free end of the second roller portion 42 , and the depth can be set according to actual needs, for example, 10 mm, to ensure good matching and supporting effects.

[0087] A flexible buffer layer 512 is disposed within the recessed portion 511, and a wear-resistant material layer 513 is disposed within the flexible buffer layer 512. The flexible buffer layer 512 can be made of rubber, which has excellent elasticity and shock absorption properties and a thickness of 5 mm to provide sufficient buffer space. The wear-resistant material layer 513 can be made of polytetrafluoroethylene (PTFE), which has an extremely low coefficient of friction and excellent wear resistance. A ceramic coating can also be used as an alternative to extend service life.

[0088] A lifting mechanism for lifting the metal ring 9 is located below the second roller portion 42 on the frame 1. This mechanism comprises a lifting cylinder 61 mounted on the frame 1 and a lifting plate 62 mounted on the piston rod of the lifting cylinder 61. The upper end surface of the lifting plate 62 is inclined, ensuring that the metal ring 9 has a tendency to move toward the first roller portion 41. The upper end surface of the lifting plate 62 is provided with anti-slip grooves with a depth of 0.5-2 mm and a wavy distribution. The angle α between the upper end surface of the lifting plate 62 and the axis of the support roller 4 is 5-15 degrees. In this embodiment, the angle α is 7 degrees.

[0089] A transition arc surface 43 is defined between the first roller portion 41 and the second roller portion 42 .

[0090] Support assemblies are respectively provided on both sides of the frame 1 below the support roller body 4, and the support assemblies include a support cylinder 71 whose bottom is hinged to the frame 1, a top pressure roller 72 rotatably provided on the piston rod of the support cylinder 71, and a rotating cylinder 73 whose bottom is hinged to the frame 1. The piston rod of the rotating cylinder 73 is hingedly connected to the support cylinder, and the top pressure roller 72 can cooperate with the metal ring body 9 on the first roller portion 41 and / or the second roller portion 42 to achieve support.

[0091] The oil cylinders mentioned above are all standard oil cylinders, and their strokes are controlled by a hydraulic system. The above-mentioned support mechanism may also adopt other structures, as long as it can support the second roller portion, and it may not be set. The above-mentioned lifting mechanism may also be other structures, the purpose of which is to lift the metal ring body so that the metal ring body can break away from the second roller portion and enter the first roller portion, and it may not be set. The support assembly may also be other structures, which mainly realizes the cooperation between the two top pressure rollers and the rolling mechanism to realize the rolling forming of the metal ring body, and it may not be set. The support assembly can be used to limit and support the final forming of the metal ring body.

[0092] Although the present invention has been particularly shown and described in conjunction with preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. A steel ring forging process, characterized in that: The following steps are involved: S1. Ingot heating: Heat the ingot to the initial forging temperature of 1150℃~1250℃. The holding time is calculated based on the weight of the ingot at 1.5 hours / ton, ensuring the temperature uniformity of ±10℃; S2. Ingot forging: adopt wide flat anvil high temperature strong pressing method, anvil width ratio 0.6-0.8, pressing rate 20%, single pressing amount does not exceed 30% of the ingot height; S3. Ingot punching: A pre-hole with a diameter of 1 / 3 to 1 / 2 of the ingot diameter is formed in the center of the forged ingot through a punching process; S4. Ring Rolling Expansion: Ring rolling mill is used for hole expansion, with the expansion ratio of the driving roller to the core roller being 2.5-3.0, the feed speed being 8-15 mm / s, and the rolling temperature being controlled at 1050-1100°C. S5. Steel ring roll forming: Through multiple roll forming processes, the outer diameter of the steel ring reaches the designed size, the deformation of a single pass does not exceed 15%, and the total deformation is ≥ 60%; S6. Steel ring cooling: Use air cooling or mist cooling, and control the cooling rate at 50℃ / h~80℃ / h to avoid surface cracks; S7. Subsequent processing: including deburring, surface polishing and dimensional accuracy inspection.

2. A steel ring forging process according to claim 1, characterized in that: In the steel ingot heating step, when the initial temperature of the steel ingot is ≥600°C, a hot delivery process is adopted, and the holding time is shortened by 20%; when the initial temperature of the steel ingot is <600°C, a cold delivery process is adopted, and the holding time is increased by 15%.

3. A steel ring forging process according to claim 1, characterized in that: In the steel ingot forging step, a two-pressing process is adopted, and a 10% anvil width overlap is retained between the two pressing parts. When turning and pressing, the anvil angle is ≥30° to ensure uniform compaction of the billet.

4. A steel ring forging process according to claim 1, characterized in that: In the steel ring rolling and expanding step, the ratio of the drive roller radius to the core roller radius (R+r) / (Rr) is 2.5-3.0, the rolling line speed is controlled at 1.5-2.0 m / s, and the ring wall thickness thinning rate is ≥40%.

5. A steel ring forging process according to claim 1, characterized in that: In the steel ring roll forming step, a rolling process with synchronous radial and axial control is adopted, the ratio of axial feed to radial feed is 1:2 to 1:3, and the ring ovality error is ≤0.5mm.

6. A steel ring forging process according to claim 1, characterized in that: In the steel ring rolling and expanding step, the initial height-to-thickness ratio of the ring is ≤6:

1. When the height-to-thickness ratio exceeds 6:1, a pre-rolling groove process is adopted, and the groove depth is 10% to 15% of the wall thickness and the width is 20% to 25% of the wall thickness.

7. A steel ring forging process according to claim 1, characterized in that: In the steel ring cooling step, when the steel ring wall thickness is ≥50mm, a graded cooling process is adopted, and the specific steps are as follows: S61, mist cooling stage: place the steel ring in a mist cooling environment, and control the cooling rate at 60℃ / h~80℃ / h until the surface temperature of the steel ring drops to 800℃; S62, air cooling stage: transfer the steel ring to an air cooling environment, and control the cooling rate at 40℃ / h~60℃ / h until the surface temperature of the steel ring drops to 400℃; S63, slow cooling stage: placing the steel ring in a heat preservation environment, and controlling the cooling rate at 10℃ / h~20℃ / h, until the surface temperature of the steel ring drops to room temperature; When the wall thickness of the steel ring is less than 50mm, a continuous air cooling process is adopted and the cooling rate is controlled at 50℃ / h~80℃ / h to avoid surface cracks.

8. A steel ring forging process according to claim 7, characterized in that: The slow cooling stage includes the following steps: S631, Insulation: Place the steel ring in an insulation device with temperature monitoring and automatic adjustment functions. The device can adjust the heating power according to the real-time temperature of the steel ring to ensure a stable cooling rate; S632, cooling rate control: the cooling rate is controlled within the range of 8°C / h to 15°C / h in the range of 400°C to 300°C; the cooling rate is controlled within the range of 5°C / h to 10°C / h in the range of 300°C to 200°C; the cooling rate is controlled within the range of 3°C / h to 8°C / h in the range of 200°C to room temperature; S633, Ambient atmosphere control: During the slow cooling stage, inert gas is filled into the insulation device to reduce oxidation on the surface of the steel ring. At the same time, the humidity in the device is controlled to avoid cracks on the surface of the steel ring due to humidity changes.

9. A steel ring forging process according to claim 8, characterized in that: The slow cooling stage also includes the following steps: S634, vibration treatment: During the slow cooling process, the steel ring can be subjected to low-frequency vibration treatment, with the vibration frequency controlled at 50Hz~100Hz and the amplitude controlled at 0.1mm~0.5mm, to promote the release of internal stress of the steel ring and reduce residual stress.

10. A steel ring forging process according to claim 9, characterized in that: In the environmental atmosphere control step, the inert gas filled is nitrogen, and the oxygen concentration is maintained at 1-5%; High-frequency and small-amplitude vibration is used in the temperature range of 400℃-300℃, and low-frequency and large-amplitude vibration is used when the temperature is less than 300℃, and the vibration adopts pulse intermittent vibration.

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