High-precision bearing outer ring hobbing forging forming method

Abstract

The application discloses a high-precision bearing outer ring horizontal rolling forging forming method, comprising the following steps: S1, blanking: selecting bearing steel bar stock, and obtaining a material section through sawing and blanking; S2, heating: placing the material section in a heating furnace for heating, the heating frequency is not more than 2 times, the initial forging temperature is controlled to be 1050 DEG C to 1130 DEG C, and the final forging temperature is controlled to be 925 DEG C to 1040 DEG C; S3, forming: sequentially performing upsetting, punching, punching, and flattening on the heated material section to obtain a ring-shaped preform; S4, horizontal rolling forming: placing the ring-shaped preform on a radial axial ring rolling mill for horizontal rolling forming to obtain a bearing outer ring forging; wherein, in the S2 heating step, when the machining process is interrupted, the interruption time t is recorded, and the temperature control is adjusted according to the interval of t as follows: when t is less than or equal to 30 min, the furnace temperature is adjusted to 900 DEG C to 1000 DEG C for heat preservation; when 30 min < t is less than or equal to 180 min, the furnace temperature is adjusted to 500 DEG C to 600 DEG C for heat preservation; when t is greater than 180 min, heating is stopped and air cooling is performed.

Description

Technical Field

[0001] This invention belongs to the field of bearing outer ring forging technology, and particularly relates to a method for horizontal rolling forging of high-precision bearing outer rings. Background Technology

[0002] In the forging process of bearing rings, the heated material section needs to undergo multiple processes, including upsetting, punching, die punching, leveling, and horizontal rolling, resulting in a long processing cycle. In actual production, processing is often interrupted due to equipment failures (such as hydraulic system malfunctions or roller breakage), die replacements, poor process coordination, or planned shutdowns (such as shift changes). After an interruption, the material section, already heated to the initial forging temperature, faces a dilemma: if it is scrapped directly, it will result in serious waste of materials and energy; if it is held at high temperature for a long time, it will lead to coarse grains, a deeper decarburized layer, or even overheating, ultimately affecting the mechanical properties and dimensional accuracy of the forging, also generating a large number of scraps.

[0003] In the prior art, CN121348903A discloses a method for handling emergencies during forging, which classifies the handling according to the duration of the fault. However, this method does not specify the target temperature range and the rate of rise and fall corresponding to each level. Therefore, in practical applications, the handling effect is limited by the operator's experience and equipment differences, and it is difficult to guarantee the consistency of the material's microstructure after the interruption. Summary of the Invention

[0004] To address the problems in the prior art, the present invention proposes the following technical solution: This invention provides a method for horizontal rolling and forging of high-precision bearing outer rings, comprising the following steps: S1. Material cutting: Select bearing steel bars and cut them into sections by sawing. S2. Heating: The material segment is placed in a heating furnace and heated no more than twice. The initial forging temperature is controlled at 1050℃~1130℃, and the final forging temperature is controlled at 925℃~1040℃. S3. Forming: The heated material segment is upsetting, punching, die punching, and leveling in sequence to obtain a ring-shaped preform; S4. Horizontal rolling forming: The annular preform is placed on a radial-axial ring rolling mill for horizontal rolling forming to obtain the bearing outer ring forging; In the S2 heating step, when the processing is interrupted, the interruption duration is recorded as t, and the temperature control is adjusted according to the interval where t is located using the following strategy: When t≤30min, adjust the furnace temperature to 900℃~1000℃ and maintain the temperature. When 30min < t ≤ 180min, adjust the furnace temperature to 500℃~600℃ and maintain the temperature. When t > 180 min, heating is stopped and air cooling is performed.

[0005] As a preferred embodiment of the above technical solution, in step S2, a combination of thermocouple and fixed infrared thermometer is used to measure the temperature. Temperature data is collected every 30 seconds and automatically recorded by a computer. An alarm is issued when the deviation between the measured furnace temperature and the target temperature control value exceeds ±15℃.

[0006] As a preferred embodiment of the above technical solution, in step S2, when an interruption occurs, the corresponding temperature control strategy is automatically selected according to the interruption duration t and a prompt signal is issued. When t moves from the low range to the high range, the heating furnace automatically switches the operating mode according to the temperature control strategy corresponding to the current range.

[0007] As a preferred embodiment of the above technical solution, in step S2, when the interruption duration t≤30min, during the period when the heating furnace maintains a temperature of 900℃~1000℃, the furnace door of the heating furnace is kept closed, and the furnace door is opened once every 5min~10min to monitor the oxygen content inside the furnace, and the oxygen content inside the furnace is controlled at ≤500ppm.

[0008] As a preferred embodiment of the above technical solution, in step S2, when the interruption duration t satisfies 30min<t≤180min, the furnace temperature is reduced from the initial forging temperature of 1050℃~1130℃ to 500℃~600℃ at a cooling rate of 5℃ / min~15℃ / min; after the interruption ends, the furnace temperature is increased from 500℃~600℃ to 1050℃~1130℃ at a heating rate of 8℃ / min~20℃ / min, and after reaching the initial forging temperature, it is held for 20min~40min before proceeding to the subsequent S3 forming step.

[0009] As a preferred embodiment of the above technical solution, in step S2, the material segment is laid out in a single layer in the furnace during heating to avoid overlapping; when the heating is stopped after the interruption time t>180min and air cooling is performed, the air-cooled material segment is marked as rework material and stored separately from the unheated material segment. When the rework material is reheated in the subsequent process, the initial forging temperature is increased by 10℃~20℃.

[0010] As a preferred embodiment of the above technical solution, in step S3, the following steps are performed sequentially: upsetting outside the die to 1.2 to 1.5 times the height of the original material segment, punching, punching with a conical die, and leveling to 95% to 105% of the height after upsetting.

[0011] The beneficial effects of this invention are as follows: (1) This invention achieves precise control of the material segment temperature after an interruption by setting a three-stage temperature control strategy based on the interruption duration t in the heating step: when the processing is interrupted, the material segment that has been heated to the initial forging temperature is in an austenitic state. If it is scrapped directly, it will cause waste of materials and energy. If it stays at high temperature for a long time, it will cause grain coarsening and decarburization layer thickening due to the amplification of atomic diffusion. According to the different effects of different interruption durations on the microstructure evolution of the material segment, the interruption duration is divided into three intervals: short, medium and long, and appropriate temperature control schemes are matched for each interval. During short interruption, a higher temperature is maintained to ensure rapid production recovery and shorten auxiliary time; during medium interruption, the temperature is appropriately reduced to reduce the atomic diffusion rate, inhibit grain growth and decarburization; during long interruption, the furnace is shut down for cooling to completely block the microstructure deterioration process at high temperature. Thus, under the premise of ensuring that the final forging quality (grain size, decarburization layer depth, etc.) is basically the same as that under normal working conditions, the waste of materials and energy caused by direct scrapping is effectively avoided, and the scrap rate and production cost are reduced.

[0012] (2) This invention provides a double guarantee for the accurate execution of the stepped temperature control strategy by setting up a high-precision combined temperature measurement and automatic control mechanism: the actual effect of the stepped temperature control strategy is highly dependent on the accuracy of furnace temperature control - if there is a deviation between the measured temperature and the target temperature, it may lead to the actual temperature control level not matching the expectation (such as the actual temperature being too high during a medium-term interruption and falling into the temperature range of a short-term interruption), thus failing to achieve the expected organizational control effect. This invention uses a combination of thermocouples and fixed infrared thermometers for temperature measurement, utilizing the high precision of thermocouples and the wide temperature range response characteristics of infrared thermometers to form a complementary relationship, and automatically records data every 30 seconds by computer and issues an alarm when the deviation exceeds ±15℃, ensuring the accuracy of temperature control at each level; at the same time, by automatically selecting the corresponding temperature control strategy according to the interruption duration and automatically switching the furnace operation mode, it avoids the strategy mismatch that may be caused by manual judgment and operation delay, ensuring the timeliness and accuracy of temperature control strategy switching, so that the entire stepped temperature control scheme can be reliably executed in actual production.

[0013] (3) The present invention further provides differentiated process control measures for the process characteristics of each interruption level, forming a synergistic effect with the step-type temperature control strategy from multiple levels. The thermal state and microstructure of the material feeding section are different for different interruption durations, and the quality risks they face are also different. During short interruptions, although the temperature is still relatively high, the oxygen in the furnace atmosphere at high temperature will continue to cause surface oxidation and decarburization. By controlling the furnace door to close and regularly monitoring the oxygen content, the concentration of oxidizing atmosphere is reduced from the source, effectively inhibiting the further expansion of the decarburized layer. During medium interruptions, the temperature goes through a process of decreasing and then increasing again. If the cooling or heating rate is too fast, the temperature difference between the inside and outside of the material section will be too large, which will generate thermal stress or even cracking risk. At the same time, the unevenness of the microstructure transformation will also affect the subsequent molding quality. By controlling the cooling rate and heating rate and setting the heat preservation and heat equalization time, it is ensured that the temperature and microstructure of the material section reach a uniform state before molding.

[0014] (4) This invention also provides supporting measures for the treatment of rework material after long-term interruption. After long-term interruption, the rework material has undergone a complete cooling-reheating cycle, and its microstructure is different from that of the unheated material. By storing it in separate areas, traceability management can be achieved. When reheating, the initial forging temperature is increased, which provides additional recrystallization nucleation driving force for the rework material. This effectively compensates for the possible changes in microstructure that may occur during the air cooling process, and ensures that the rework material can obtain the same molding quality as the normal material after reheating. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0016] Example 1

[0017] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars were selected, with a diameter of ø250mm. A GZ4250 CNC saw was used for sawing, controlling the blank weight to 236Kg, the blank length to 612mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and the end face inclination was checked using an angle gauge. Blanks exceeding these tolerances were immediately isolated, and the sawing parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0018] S2, Heating The material segment is placed in a natural gas heating furnace and heated once. The material segment is laid out in a single layer in the furnace to avoid overlapping. The initial forging temperature is controlled at 1090℃, and the final forging temperature is controlled at 1040℃.

[0019] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than +15°C.

[0020] A machine malfunction occurred during the heating process, causing the processing to be interrupted. The interruption duration was recorded as t=120min.

[0021] When an interruption occurs, the system automatically selects the corresponding temperature control strategy based on the interruption duration t and issues a prompt signal. The heating furnace automatically switches to the second operating mode, reducing the furnace temperature from the initial forging temperature of 1090℃ to 550℃ at a cooling rate of 10℃ / min for holding. The oxygen content inside the furnace is controlled at 500ppm.

[0022] After the interruption ends, the furnace temperature is increased from 550℃ to 1090℃ at a rate of 14℃ / min. After reaching the initial forging temperature, it is held for 30 minutes before proceeding with the subsequent steps.

[0023] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.35 times the original material segment height; Punching: Punching is performed using a punch, with the punch diameter controlled at ø190mm; Die: A tapered die is used for punching, with die specifications ranging from ø445 to 300 mm; Leveling: The annular preform is leveled to 100% of its height after upsetting to obtain an annular preform with a height of 221mm after leveling.

[0024] S4, Horizontal rolling forming The annular preform is placed on a DA53K-250-160-3000-500 CNC radial axial ring rolling mill, and horizontally rolled using a ø180mm mandrel and a ø990-661mm bottom roller. The forging ratio is 20.4, resulting in the bearing outer ring forging. During the ring rolling process, 100% inspection is performed on the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height. The rolling ratio and forging speed are adjusted to avoid insufficient rolling.

[0025] Example 2

[0026] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars with a diameter of ø200mm were used. A GZ4240 CNC saw was employed for sawing, controlling the weight at 152kg, the length at 510mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and end face inclination was checked using an angle gauge. Materials exceeding these tolerances were immediately isolated, and saw parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0027] S2, Heating The material section is placed in a natural gas heater and heated once. The material section is laid out in a single layer in the furnace, avoiding overlap. The initial forging temperature is controlled at 1090℃, and the final forging temperature is controlled at 1040℃.

[0028] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than +15°C.

[0029] A machine malfunction occurred during the heating process, causing the processing to be interrupted. The interruption duration was recorded as t=20min. When an interruption occurs, the system automatically selects the corresponding temperature control strategy based on the interruption duration t and issues a prompt signal. The heating furnace automatically switches to the first operating mode. The furnace temperature is reduced from 1090℃ to 950℃ at a cooling rate of 10℃ / min for holding. During the holding period, the furnace door remains closed, and is opened every 7 minutes to monitor the oxygen content inside the furnace, which is controlled at 500ppm.

[0030] After the interruption ends, the heating furnace automatically switches back to normal heating mode, raising the furnace temperature to the initial forging temperature of 1090℃, and continues with subsequent steps.

[0031] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.35 times the original material segment height; Punching: Punching is performed using a punch, with the punch diameter controlled at ø150mm; Die: A tapered die is used for punching, with die specifications ranging from ø380 to 260 mm; Leveling: The annular preform is leveled to 100% of its height after upsetting to obtain an annular preform with a height of 184mm after leveling.

[0032] S4, Horizontal rolling forming The annular preform is placed on a DA53K-200-130-2500-400 CNC radial axial ring rolling mill, and horizontally rolled using a ø150mm mandrel and ø800-530mm bottom roller. The forging ratio is 18.5, resulting in the bearing outer ring forging. During the ring rolling process, 100% inspection is performed on the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height. The rolling ratio and forging speed are adjusted to avoid insufficient rolling.

[0033] Example 3

[0034] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars were selected, with a diameter of ø300mm. A GZ4265 CNC saw was used for sawing, controlling the blank weight to 342Kg, the blank length to 720mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and the end face inclination was checked using an angle gauge. Blanks exceeding these tolerances were immediately isolated, and the sawing parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0035] S2, Heating The material section is placed in a natural gas heater and heated once. The material section is laid out in a single layer in the furnace, avoiding overlap. The initial forging temperature is controlled at 1090℃, and the final forging temperature is controlled at 1040℃.

[0036] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than +15°C.

[0037] A machine malfunction occurred during the heating process, causing the processing to be interrupted. The interruption duration was recorded as t=240min.

[0038] When an interruption occurs, the system automatically selects the corresponding temperature control strategy based on the interruption duration t and issues a prompt signal. The heating furnace automatically switches to the third operating mode, stops heating, and begins air cooling.

[0039] After air cooling, the air-cooled material segments are marked as rework material and stored separately from the unheated material segments. When the rework material is reheated later, the initial forging temperature is increased to 1105℃ (i.e., 15℃ higher than 1090℃).

[0040] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.35 times the original material segment height; Punching: Punching is performed using a punch, and the punching diameter is controlled to be ø230mm; Die: A tapered die is used for punching, with die specifications ranging from ø530 to 360 mm; Leveling: The annular preform is leveled to 100% of its height after upsetting to obtain an annular preform with a height of 260mm after leveling.

[0041] S4, Horizontal rolling forming The annular preform is placed on a DA53K-315-200-4000-630 CNC radial axial ring rolling mill, and horizontally rolled using a ø220mm mandrel and a ø1200-800mm bottom roller, with a forging ratio of 22.0, to obtain the bearing outer ring forging. During the ring rolling process, 100% inspection is performed on the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height. The rolling ratio and forging speed are adjusted to avoid insufficient rolling.

[0042] Example 4

[0043] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars were selected, with a diameter of ø220mm. A GZ4240 CNC saw was used for sawing, controlling the blank weight to 183Kg, the blank length to 560mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and the end face inclination was checked using an angle gauge. Blanks exceeding these tolerances were immediately isolated, and the sawing parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0044] S2, Heating The material section is placed in a natural gas heater and heated once. The material section is laid out in a single layer in the furnace, avoiding overlap. The initial forging temperature is controlled at 1090℃, and the final forging temperature is controlled at 1040℃.

[0045] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than +15°C.

[0046] The processing was uninterrupted; the material section was heated once and then moved directly to the next step.

[0047] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.35 times the original material segment height; Punching: Punching is performed using a punch, with the punch diameter controlled at ø165mm; Die: A tapered die is used for punching, with die specifications of ø400-275mm; Leveling: The annular preform is leveled to 100% of its height after upsetting to obtain an annular preform with a height of 202mm after leveling.

[0048] S4, Horizontal rolling forming The annular preform was placed on a DA53K-220-140-2800-450 CNC radial axial ring rolling mill, and horizontally rolled using a ø160mm mandrel and ø880-580mm bottom roller. The forging ratio was 19.2, resulting in the bearing outer ring forging. During the ring rolling process, 100% inspection was performed on the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height. The rolling ratio and forging speed were adjusted to avoid insufficient rolling.

[0049] Example 5

[0050] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars were selected, with a diameter of ø180mm. A GZ4235 CNC saw was used for sawing, controlling the blank weight to 123Kg, the blank length to 460mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and the end face inclination was checked using an angle gauge. Blanks exceeding these tolerances were immediately isolated, and the sawing parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0051] S2, Heating The material section is placed in a natural gas heating furnace and heated twice. The material section is laid out in a single layer in the furnace, avoiding overlap. The initial forging temperature is controlled at 1050℃, and the final forging temperature is controlled at 925℃.

[0052] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than ±15℃.

[0053] The processing was not interrupted. After the first heating was completed, S3 forming was carried out, and after the second heating was completed, S4 horizontal rolling forming was carried out.

[0054] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.2 times the original material segment height; Punching: Punching is performed using a punch, with the punch diameter controlled at ø130mm; Die: A tapered die is used for punching, with die specifications ranging from ø340 to 230 mm; Leveling: The annular preform is leveled to 95% of its height after upsetting to obtain an annular preform with a height of 166mm after leveling.

[0055] S4, Horizontal rolling forming The annular preform was placed on a DA53K-180-110-2200-350 CNC radial axial ring rolling mill, and horizontally rolled using a ø130mm mandrel and ø720-480mm bottom roller. The forging ratio was 17.5, resulting in the bearing outer ring forging. During the ring rolling process, 100% of the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height were inspected. The rolling ratio and forging speed were adjusted to avoid insufficient rolling.

[0056] Example 6

[0057] This embodiment provides a method for horizontal rolling and forging of a high-precision bearing outer ring, including the following steps: S1, Material feeding 100CrMo7-3 bearing steel bars were selected, with a diameter of ø350mm. A GZ4280 CNC saw was used for sawing, controlling the blank weight to 462Kg, the blank length to 840mm, the end face inclination to no more than 2.5°, and the burrs to less than 1.0mm. Weight was sampled and checked using an electronic platform scale, and the end face inclination was checked using an angle gauge. Blanks exceeding these tolerances were immediately isolated, and the sawing parameters were adjusted. Simultaneously, full-process traceability of furnace number and grade was achieved.

[0058] S2, Heating The material section is placed in a natural gas heating furnace and heated twice. The material section is laid out in a single layer in the furnace to avoid overlapping. The initial forging temperature is controlled at 1130℃, and the final forging temperature is controlled at 1040℃.

[0059] Temperature is measured using a combination of thermocouples and a fixed infrared thermometer, with temperature data collected every 30 seconds and automatically recorded by a computer. The thermocouples are fixed in place to prevent misalignment, and the fixed infrared thermometer is calibrated once per shift. An alarm is triggered when the measured furnace temperature deviates from the target temperature control value by more than +15°C.

[0060] The processing was not interrupted. After the first heating was completed, S3 forming was carried out, and after the second heating was completed, S4 horizontal rolling forming was carried out.

[0061] S3, Molding The heated material section will be processed in the following steps: External upsetting: Upsetting the material segment to 1.5 times the original material segment height; Punching: Punching is performed using a punch, with the punch diameter controlled at ø270mm; Die: A tapered die is used for punching, with die specifications ranging from ø620 to 420mm; Leveling: The annular preform is leveled to 105% of its height after upsetting to obtain an annular preform with a height of 304mm after leveling.

[0062] S4, Horizontal rolling forming The annular preform is placed on a DA53K-350-220-4500-700 CNC radial axial ring rolling mill, and horizontally rolled using a ø250mm mandrel and a ø1350-900mm bottom roller. The forging ratio is 23.5, resulting in the bearing outer ring forging. During the ring rolling process, 100% inspection is performed on the outer diameter of the large end, the outer diameter of the small end, the inner diameter, and the height. The rolling ratio and forging speed are adjusted to avoid insufficient rolling.

[0063] Example 7

[0064] The only difference from Example 2 is that the interruption time t=30min, the furnace temperature is reduced from 1090℃ to 900℃ at a cooling rate of 10℃ / min and then held at that temperature; during the holding period, the furnace door is opened every 5min to monitor the oxygen content inside the furnace, and the oxygen content is ≤500ppm. The remaining steps (material specifications, molding and rolling ring parameters) are the same as in Example 2.

[0065] Example 8

[0066] The only difference from Example 1 is that the interruption time is t=180min, during which the furnace temperature is reduced from the initial forging temperature of 1090℃ to 500℃ at a cooling rate of 5℃ / min and held at that temperature; after the interruption, the temperature is increased from 500℃ to 1090℃ at a heating rate of 8℃ / min, and held at that temperature for 20min before proceeding with the subsequent steps. All other steps (material specifications, forming, and rolling parameters) are the same as in Example 1.

[0067] Example 9

[0068] The only difference from Example 3 is that the initial forging temperature of the rework material is increased to 1100°C during subsequent reheating. The remaining steps (interruption time t=240min, air cooling, zoned storage, forming and rolling parameters) are the same as in Example 3.

[0069] Example 10

[0070] The only difference from Example 7 is that the interruption time t=30min, the furnace temperature is reduced from 1090℃ to 1000℃ at a cooling rate of 10℃ / min and then held at that temperature; during the holding period, the furnace door is opened every 10min to monitor the oxygen content inside the furnace, and the oxygen content is ≤500ppm. The remaining steps (material specifications, molding and rolling ring parameters) are the same as in Example 7.

[0071] Example 11

[0072] The only difference from Example 8 is that the interruption time is t=180min, during which the furnace temperature is reduced from the initial forging temperature of 1090℃ to 600℃ at a cooling rate of 15℃ / min and held at that temperature; after the interruption, the temperature is increased from 600℃ to 1090℃ at a heating rate of 20℃ / min, and held at that temperature for 40min before proceeding with the subsequent steps. All other steps (material specifications, forming, and ring rolling parameters) are the same as in Example 8.

[0073] Example 12

[0074] The only difference between this embodiment and Embodiment 9 is that the initial forging temperature of the rework material is increased to 1110℃ during subsequent reheating. The remaining steps (interruption time t=240min, air cooling, zoned storage, forming and ring rolling parameters) are the same as in Embodiment 9.

[0075] Comparative Example 1 The difference between this comparative example and Example 1 is that after an interruption occurred during the processing (t=120min), the step-by-step cooling and heat preservation strategy of this invention was not carried out. Instead, the furnace temperature was directly maintained at the initial forging temperature of 1090℃ for continuous heat preservation, and the subsequent forming steps were carried out directly after the interruption ended.

[0076] Comparative Example 2 The difference between this comparative example and Example 1 is that after an interruption occurred during the processing (t=120min), the heated material section was directly scrapped, and the material was fed back in for heating and molding after the equipment returned to normal.

[0077] Comparative Example 3 The difference between this comparative example and Example 3 is that: after the processing was interrupted (t=240min), the material segment was taken out of the furnace and forced to cool to room temperature. After the interruption ended, the cooled material segment was reheated to 1090℃ and then directly carried out the subsequent forming steps. The initial forging temperature of the rework material was not increased according to the present invention.

[0078] Performance testing The bearing outer ring forgings obtained in the above embodiments and comparative examples were subjected to performance testing. The testing items included grain size, decarburized layer depth, and scrap rate.

[0079] Grain size testing: Metallographic samples were cut from the same location (outer diameter surface) of the bearing outer ring forgings obtained in each embodiment and comparative example. After grinding, polishing and etching, the austenite grain size was determined according to the comparative method in GB / T 6394 "Method for Determination of Average Grain Size of Metals".

[0080] Decarburization layer depth detection: Metallographic samples were cut from the bearing outer ring forgings obtained in each embodiment and comparative example. After inlaying, grinding and polishing, the decarburization layer depth was determined by metallographic method in GB / T 224 "Method for Determination of Decarburization Layer Depth of Steel".

[0081] Scrap rate statistics: 100% dimensional inspection (large end outer diameter, small end outer diameter, inner diameter, height) and surface quality inspection were carried out on the bearing outer ring forgings obtained in each embodiment and comparative example. The scrap rate caused by dimensional deviation or surface defects (cracks, folds, excessive oxide scale, etc.) was calculated.

[0082] The test results are shown in Table 1.

[0083]

[0084] Table 1 Note 1 Comparative Example 3: The grain size is uneven, and mixed crystals appear in some areas. The grain size rating is 6.2.

[0085] As shown in Table 1, the grain size of the bearing outer ring forgings obtained in each embodiment of the present invention is all above grade 7.0, the decarburized layer depth is all ≤0.20mm, and the scrap rate is all ≤2.0%, all meeting the product technical requirements of precision bearing outer rings. Comparative Example 1, due to prolonged holding at the initial forging temperature after interruption, resulted in grain coarsening to grade 5.5, a decarburized layer as high as 0.35mm, and a scrap rate of 8.2%, failing to meet the requirements. Comparative Example 3, due to insufficient recrystallization nucleation driving force because the initial forging temperature of the rework material was not increased, resulted in mixed crystals (grade 6.2) and a scrap rate of 4.5%, also failing to meet the requirements. Comparative Example 2, although directly scrapped, did not produce defective forgings, but caused significant material waste and energy loss. In summary, the present invention, through stepped temperature control based on the interruption duration, allows the interrupted material segment to continue to be used and avoids scrapping, significantly improving material utilization and production efficiency while ensuring product quality, fully demonstrating the reliability and wide applicability of the technical solution of the present invention.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A method for horizontal rolling and forging of high-precision bearing outer rings, characterized in that, Includes the following steps: S1. Material cutting: Select bearing steel bars and cut them into sections by sawing. S2. Heating: The material segment is placed in a heating furnace and heated no more than twice. The initial forging temperature is controlled at 1050℃~1130℃, and the final forging temperature is controlled at 925℃~1040℃. S3. Forming: The heated material segment is upsetting, punching, die punching, and leveling in sequence to obtain a ring-shaped preform; S4. Horizontal rolling forming: The annular preform is placed on a radial-axial ring rolling mill for horizontal rolling forming to obtain the bearing outer ring forging; In the S2 heating step, when the processing is interrupted, the interruption duration is recorded as t, and the temperature control is adjusted according to the interval where t is located using the following strategy: When t≤30min, adjust the furnace temperature to 900℃~1000℃ and maintain the temperature. When 30min < t ≤ 180min, adjust the furnace temperature to 500℃~600℃ and maintain the temperature. When t > 180 min, stop heating and start air cooling.

2. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S2, a combination of thermocouple and fixed infrared thermometer is used to measure temperature. Temperature data is collected every 30 seconds and automatically recorded by computer. An alarm is issued when the deviation between the measured furnace temperature and the target temperature control value exceeds ±15℃.

3. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S2, when an interruption occurs, the corresponding temperature control strategy is automatically selected and a prompt signal is issued according to the interruption duration t. When t moves from the low range to the high range, the heating furnace automatically switches the operating mode according to the temperature control strategy corresponding to the current range.

4. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S2, when the interruption duration t≤30min, the furnace door is kept closed during the period when the heating furnace is kept at 900℃~1000℃. The furnace door is opened once every 5min~10min to monitor the oxygen content inside the furnace, and the oxygen content inside the furnace is controlled at ≤500ppm.

5. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S2, when the interruption duration t satisfies 30min<t≤180min, the furnace temperature is reduced from the initial forging temperature of 1050℃~1130℃ to 500℃~600℃ at a cooling rate of 5℃ / min~15℃ / min; after the interruption ends, the furnace temperature is increased from 500℃~600℃ to 1050℃~1130℃ at a heating rate of 8℃ / min~20℃ / min, and after reaching the initial forging temperature, it is held for 20min~40min before proceeding to the subsequent S3 forming step.

6. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S2, the material segments are laid out in a single layer in the furnace during heating to avoid overlapping. When the heating is stopped after the interruption time t>180min and air cooling is performed, the air-cooled material segments are marked as rework material and stored separately from the unheated material segments. When the rework material is reheated in the subsequent process, the initial forging temperature is increased by 10℃~20℃.

7. The method for horizontal rolling and forging of high-precision bearing outer rings according to claim 1, characterized in that, In step S3, the following steps are performed sequentially: upsetting outside the die to 1.2 to 1.5 times the height of the original material section, punching, punching with a conical die, and leveling to 95% to 105% of the height after upsetting.

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