Forming method and device for hot-forging and upsetting bearing ring of round steel

Abstract

The application discloses a forming method and device for a round-steel hot-forging and rolling-expanding bearing ring, and comprises the following steps: S1, blank preparation, feeding bearing round-steel bars into a cutting machine to cut into pie blanks with equal length; S2, heating, feeding the pie blanks obtained in S1 into a heating device to heat, and the heating temperature is 1100 DEG C to 1180 DEG C; S3, ring forging, putting the high-temperature pie blanks in S2 into a forging die of a press to stamp to obtain a ring blank, the forging temperature is kept between 950 DEG C and 1250 DEG C, and the pie blanks can be heated again in a furnace at low temperature; and S4, hot rolling-expanding, feeding the ring blank obtained in S2 into a ring rolling machine to roll-expand, the initial temperature for rolling-expanding is 1070 DEG C to 1120 DEG C, the stop temperature is 850 DEG C to 900 DEG C, and the atmosphere used for rolling-expanding is nitrogen. The method is used for step-by-step ring forging, guarantees processing quality and efficiency, the position of the bearing ring is constrained by a conical positioning ring on the outer side of a plate and a roller, the precision is guaranteed, the groove forming position is accurate, and the method also prevents the bearing ring from deviating due to vibration during ring rolling.

Description

Technical Field

[0001] This invention relates to the field of bearing ring processing technology, and in particular to a forming method and apparatus for hot forging and rolling bearing rings from round steel. Background Technology

[0002] The existing forging and rolling process for bearing blank rings involves cutting the bearing steel bar into segments using sawing or hot cutting according to the technical requirements for ring material. These segments are then heated in a furnace and extruded and rolled into shape on a press and rolling mill. The specific process is as follows: blanking → material distribution → heating → forging rings [upsetting → extrusion forming (ring material)] → bottom cutting and flattening (flattening) → rolling.

[0003] In the entire manufacturing process of bearing rings, heating, forging, and rolling are the three key steps in forming. The quality of bearing rings depends mainly on whether the batch of blanks is heated evenly and sufficiently, the magnitude of forging deformation, and the accuracy and deviation of groove positioning during rolling. Existing bearing ring manufacturing technologies do not provide detailed descriptions of these key manufacturing nodes. Often, to maximize efficiency and ensure processing temperatures, bearing ring manufacturing is carried out in a straightforward manner, with extremely high speeds for heating, stamping (forging), and hot rolling, making precise control impossible. This results in a very high defect rate for bearing rings, frequent pressure holding and straightening issues, and significantly increased subsequent costs. Summary of the Invention

[0004] The purpose of this invention is to provide a forming method and apparatus for hot forging and rolling bearing rings from round steel, in order to solve the problems in existing bearing ring processing technology where the heating, forging and hot rolling speeds are extremely fast, making precise control impossible, resulting in a very high defect rate, and requiring a lot of pressure holding and straightening, which greatly increases subsequent costs.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for forming a bearing ring by hot forging and rolling of round steel, the method comprising the following steps: S1. Blank making: The bearing round steel bar is fed into the steel cutting machine and cut into equal-length blanks. S2. Heating: Several cakes obtained in S1 are sent to a heating device for heating at a temperature of 1100℃~1180℃. S3, Forging Ring: The high-temperature blank in S2 is placed into the forging die of the press and stamped to form a ring blank. The forging temperature is maintained between 950℃ and 1250℃. At low temperatures, it can be reheated in the furnace. S4. Hot rolling expansion: The ring blank obtained in S2 is fed into a ring rolling mill for rolling expansion. The initial rolling temperature is 1070℃~1120℃, and the stopping temperature is 850℃~900℃. The atmosphere used for rolling expansion is nitrogen.

[0006] A further technical solution is as follows: In step S2, a sealed nitrogen vibration electric heating furnace is used, with nitrogen purity of 98% or higher, and the temperature rise is controlled as follows: a. Heating stage: The room temperature rises to 180℃, with a heating rate of 12℃ / min; b. Constant temperature coupling section: 180℃ for 90 min, low frequency vibration is applied simultaneously: vibration frequency 32Hz, amplitude 0.12mm, the tooling in the furnace vibrates synchronously with the vibration table, and the workpiece is laid flat in a single layer to reduce stacking. c. Slow cooling section: The furnace temperature is reduced to 65℃, with a cooling rate of ≤6℃ / min. Air cooling after removal from the furnace is prohibited.

[0007] A further technical solution is: in S3, the blank is formed into a ring blank after being forged, upset, reverse extruded and repressed in sequence on the forging die.

[0008] A further technical solution is that the forging die is provided with a forging station, an upsetting station, a reverse extrusion station and a repressing station in sequence along the material advancing direction.

[0009] A further technical solution is: in S3, a sequential punching blind hole is provided between the upsetting cake and the reverse extrusion, and the thickness of the blind hole bottom does not exceed 3mm.

[0010] A further technical solution is: In step S4, the hot rolling expansion adopts a CNC radial axial rolling mill, and the roller surface is preheated to 800℃. a. First-stage high-temperature rough rolling 1070℃~1120℃: radial feed 2.2mm / s, completing 75% deformation, rolling expansion ratio 1.4~1.7; b. Secondary medium-temperature fine rolling 900℃~940℃: feed is reduced to 0.8mm / s, and the last 10s are spent without feed for smooth rolling and shaping, with a final rolling temperature ≥850℃.

[0011] A forming device for hot forging and rolling bearing rings from round steel, wherein the device employs a forming method for production; The device includes a round steel feeder, a steel cutter, an electric heating furnace, a material handling machine, a press, a ring rolling mill, a sizing machine, and an air-cooled chain machine, arranged sequentially and connected in the process direction; wherein... The press is equipped with a forging die for high-temperature blanks at the stamping station. The outer side of the rollers of the ring rolling machine is provided with a conical positioning ring, and a backing plate adapted to the conical positioning ring is detachably provided on the ring rolling machine.

[0012] A further technical solution is that the rolling wheel includes a rolling wheel, a support wheel, and a signal wheel.

[0013] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: This invention proposes a forming method and apparatus for hot forging and rolling bearing rings from round steel. During processing, the initial heating temperature is strictly controlled to ensure that the forging process is not interrupted due to temperature drop, thus affecting processing efficiency. Controlling the processing temperature and atmosphere of hot rolling and rolling ensures the quality of plastic forming of the metal, controls the evolution of microstructure, and prevents oxidation damage to the material surface. It also helps to promote the welding of internal defects that occur during forging.

[0014] During the hot rolling expansion of the ring rolling machine, the position of the bearing ring is constrained by the back plate and the conical positioning ring on the outside of the roller to ensure accuracy, thereby ensuring the accurate positioning of the groove forming position, and also to prevent the ring from deviating due to vibration during rolling. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the forming device for hot forging and expanding bearing rings from round steel according to the present invention.

[0016] Figure 2 For the present invention Figure 1 A schematic diagram of the structure of a medium-sized ring rolling mill.

[0017] Figure 3 For the present invention Figure 2 A schematic diagram of the structure of the middle roller.

[0018] Figure 4 This is a schematic diagram of the forging die in this invention.

[0019] Figure 5 For the present invention Figure 4 A schematic diagram of the half-section structure.

[0020] Figure 6 For the present invention Figure 5 Another structural diagram.

[0021] Figure 7 This is a schematic diagram of the forging process of the bearing ring of the present invention.

[0022] Attached reference numerals: 1. Forging station; 2. Upsetting station; 3. Reverse extrusion station; 4. Re-pressing station; 5. Round steel feeder; 6. Steel cutting machine; 7. Electric heating furnace; 8. Material handling machine; 9. Press; 10. Ring rolling machine; 11. Sizing machine; 12. Air-cooled chain machine; 13. Roller; 14. Conical positioning ring; 15. Backing plate. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Example

[0029] This implementation example Figure 7As shown in the diagram (forming sequence from left to right), a method for forming a hot-forged and expanded bearing ring from round steel includes the following steps: S1. Blank making: The bearing round steel bar is fed into the steel cutting machine and cut into equal-length blanks. S2. Heating: Several cakes obtained in S1 are sent to a heating device for heating at a temperature of 1100℃~1180℃. S3, Forging Ring: The high-temperature blank in S2 is placed into the forging die of the press and stamped to form a ring blank. The forging temperature is maintained between 950℃ and 1250℃. At low temperatures, it can be reheated in the furnace. S4. Hot rolling expansion: The ring blank obtained in S2 is fed into a ring rolling mill for rolling expansion. The initial rolling temperature is 1070℃~1120℃, and the stopping temperature is 850℃~900℃. The atmosphere used for rolling expansion is nitrogen.

[0030] Firstly, the general forming process of the bearing ring follows the existing technical route, but the processing temperature is refined. Heating is a "pre-activation" step for hot forging. 1100℃~1180℃ ensures the material is easily deformable while minimizing excessive grain coarsening, heating the steel billet from room temperature to the austenitizing temperature range. At this high temperature, the yield strength of the steel decreases significantly, its plasticity reaches its optimal state, and a phase transformation occurs in the internal structure, providing conditions for subsequent intense plastic deformation. Strict control of the initial heating temperature ensures that the forging process is not interrupted due to temperature drops during step-by-step forging, thus affecting processing efficiency. Controlling the processing temperature and atmosphere during hot rolling ensures the quality of the metal's plastic forming, controls the evolution of the microstructure, prevents surface oxidation damage, and also helps promote the welding of internal defects that occur during forging.

[0031] Note that in S4, "entering at 1070℃~1120℃" ensures low deformation resistance and easy forging; "stopping at 850℃~900℃" ensures sufficient temperature for dynamic recrystallization during final forging, without causing grain growth. Combined with a "nitrogen atmosphere," a coordinated approach is achieved at the microscopic level between "shape control (precise dimensions)" and "property control (dense microstructure, no surface decarburization)."

[0032] Preferably, in S2, a sealed nitrogen-filled vibrating electric heating furnace is used, with nitrogen purity of 98% or higher, and the temperature is controlled as follows: a. Heating stage: The room temperature rises to 180℃, with a heating rate of 12℃ / min; b. Constant temperature coupling section: 180℃ for 90 min, low frequency vibration is applied simultaneously: vibration frequency 32Hz, amplitude 0.12mm, the tooling in the furnace vibrates synchronously with the vibration table, and the workpiece is laid flat in a single layer to reduce stacking. c. Slow cooling section: The furnace temperature is reduced to 65℃, with a cooling rate of ≤6℃ / min. Air cooling after removal from the furnace is prohibited.

[0033] The room temperature is raised to 180℃ for preheating, and the heating rate is controlled at 12℃ / min to help heat the blank thoroughly. Vibrating and flattening the blank ensures that each blank is heated evenly and fully. The vibration at high temperature also helps remove oxide scale (which includes impurities and oil stains on the blank surface). Any dried or charred oxide scale is easily removed by vibration and impact. The nitrogen gas has a purity of 98% and contains a small amount of rarefied oxygen, which forms a thin oxide scale on the blank surface. This thin oxide scale is easily removed by vibration or other methods, and it also acts as an outer insulating layer, preventing the formation of a thicker oxide layer even after the blank is removed, thus reducing the impact of subsequent oxide scale on processing.

[0034] Preferably, in step S3, the blank is formed into a ring blank after being forged, upsetting, reverse extrusion, and repressing sequentially on the forging die. The forging die is provided with forging station 1, upsetting station 2, reverse extrusion station 3, and repressing station 4 sequentially along the material advance direction.

[0035] In the general bearing machining process, the ring forming (forging) step involves directly punching through the blank. For narrower bearing rings, this can easily cause deformation. The traditional direct punching step is broken down into four consecutive steps, known as the "four-step method." First, the "four-step method" reduces the stress and deformation of the blank in each step. Second, the deformation of the blank is small in each step, resulting in fewer "internal damages." Third, for larger bearing rings, the four-step method can reduce the pressure in each step.

[0036] Preferably, in S3, a sequential punching blind hole is provided between the upsetting cake and the reverse extrusion, and the thickness of the bottom of the blind hole does not exceed 3mm.

[0037] Blind holes are punched to prevent unevenness at the bottom of the bearing ring caused by full penetration. By using blind hole forming, a certain thickness is retained at the bottom to prevent penetration. This ensures that the blank has a regular shape when pressure is applied. Finally, the blank is punched through in another process. The force is small and the speed is fast. The deformation and punching of the blank are small, which facilitates the shaping of the re-pressing process.

[0038] Preferably, in S4, the hot rolling expansion is performed using a CNC radial axial rolling mill, with the roller surface preheated to 800°C. a. First-stage high-temperature rough rolling 1070℃~1120℃: radial feed 2.2mm / s, completing 75% deformation, rolling expansion ratio 1.4~1.7; b. Secondary medium-temperature fine rolling 900℃~940℃: feed is reduced to 0.8mm / s, and the last 10s are spent without feed for smooth rolling and shaping, with a final rolling temperature ≥850℃.

[0039] Preheating the roll surface to 800℃ prevents rapid cooling and thermal fatigue: This avoids drastic heat exchange between the high-temperature (above 1000℃) billet and the room-temperature roll, which could lead to rapid hardening of the workpiece surface or thermal fatigue cracks in the roll. Stabilizing deformation resistance: Maintaining a gentle temperature gradient at the workpiece-die interface ensures uniform flow resistance of the metal within the deformation zone, preventing uneven wall thickness caused by localized temperature differences.

[0040] The first-stage high-temperature rough rolling, within the high-temperature, high-plasticity range, rapidly completes most of the wall thickness reduction and diameter expansion of the ring through a relatively fast feed rate. High temperature combined with a large deformation (75%) utilizes deformation heat and compressive stress to completely eliminate any remaining micropores inside the S3 ring blank, resulting in a highly dense microstructure.

[0041] Secondary medium-temperature precision rolling reduces temperature and feed rate, enabling precision rolling with minimal deformation. This improves dimensional accuracy: the increased deformation resistance of the material at medium temperatures and the smaller feed rate allow for a stronger "ironing" effect of the rolls on the metal, effectively eliminating surface ripples and dimensional fluctuations generated during rough rolling. Grain refinement: 900℃~940℃ is the ideal temperature range for dynamic recrystallization in bearing steel. Appropriate deformation further breaks down coarse grains, resulting in a fine and uniform microstructure, significantly improving the contact fatigue life of bearings.

[0042] The final 10 seconds of feedless finishing rolling (final rolling temperature ≥850℃) eliminates elastic recovery and roundness calibration: Metal exhibits elastic rebound after plastic deformation. Finish rolling is equivalent to "pressure holding shaping," which can completely release residual stress, eliminate geometric defects such as ellipticity and taper, and lock in the final dimensions. Improved surface finish: Feedless rolling can flatten tiny protrusions on the surface, achieving near-net-shape surface quality on both the inner and outer surfaces of the ring. Prevention of low-temperature cracking (final temperature control): Strictly limiting the final rolling temperature to ≥850℃ is to avoid the "blue brittleness zone" and low-temperature deformation zone of the steel, preventing microcracks caused by dislocation pile-up due to excessively low temperatures. Example

[0043] Based on the above embodiments, this embodiment, for example Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, a forming device for hot forging and rolling bearing rings from round steel is used for production. The equipment includes a round steel feeder 5, a steel cutter 6, an electric heating furnace 7, a material handling machine 8, a press 9, a ring rolling mill 10, a sizing machine 11, and an air-cooled chain machine 12, arranged sequentially and connected in the process direction; among which, The stamping station of press 9 is equipped with forging dies for high-temperature blanks; A conical positioning ring 14 is provided on the outer side of the roller 13 of the ring rolling machine 10, and a backing plate 15 adapted to the conical positioning ring 14 is detachably provided on the ring rolling machine 10. The rolling roller 13 includes a rolling roller 131, a support roller 132 and a signal roller 133.

[0044] During the hot rolling expansion of the ring rolling machine, the position of the bearing ring is constrained by the back plate and the conical positioning ring on the outside of the roller to ensure accuracy, thereby ensuring the accurate positioning of the groove forming position, and also to prevent the ring from deviating due to vibration during rolling.

[0045] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for forming a bearing ring by hot forging and rolling of round steel, characterized in that, The method includes the following steps: S1. Blank making: The bearing round steel bar is fed into the steel cutting machine and cut into equal-length blanks. S2. Heating: Several cakes obtained in S1 are sent to a heating device for heating at a temperature of 1100℃~1180℃. S3, Forging Ring: The high-temperature blank in S2 is placed into the forging die of the press and stamped to form a ring blank. The forging temperature is maintained between 950℃ and 1250℃. At low temperatures, it can be reheated in the furnace. S4. Hot rolling expansion: The ring blank obtained in S2 is fed into a ring rolling mill for rolling expansion. The initial rolling temperature is 1070℃~1120℃, and the stopping temperature is 850℃~900℃. The atmosphere used for rolling expansion is nitrogen.

2. The forming method of the hot forging and rolling bearing ring of round steel according to claim 1, characterized in that, In step S2, a sealed nitrogen-filled vibrating electric heating furnace is used, with nitrogen purity of 98% or higher. The temperature is controlled as follows: a. Heating stage: The room temperature rises to 180℃, with a heating rate of 12℃ / min; b. Constant temperature coupling section: 180℃ for 90 min, low frequency vibration is applied simultaneously: vibration frequency 32Hz, amplitude 0.12mm, the tooling in the furnace vibrates synchronously with the vibration table, and the workpiece is laid flat in a single layer to reduce stacking. c. Slow cooling section: The furnace temperature is reduced to 65℃, with a cooling rate of ≤6℃ / min. Air cooling after removal from the furnace is prohibited.

3. The forming method of hot forging and expanding bearing rings from round steel according to claim 1, characterized in that: In S3, the blank is formed into a ring blank after being forged, upset, reverse extruded and repressed in sequence on the forging die.

4. The forming method of hot forging and expanding bearing rings from round steel according to claim 3, characterized in that: The forging die is provided with a forging station (1), an upsetting station (2), a reverse extrusion station (3), and a repressing station (4) in sequence along the material advancing direction.

5. The forming method of hot forging and expanding bearing rings from round steel according to claim 3, characterized in that: In S3, a sequential punching blind hole is provided between the upsetting cake and the reverse extrusion, and the thickness of the blind hole bottom does not exceed 3mm.

6. The forming method of hot forging and expanding bearing rings from round steel according to claim 1, characterized in that, In step S4, the hot rolling expansion is performed using a CNC radial axial rolling mill, with the roller surface preheated to 800°C. a. First-stage high-temperature rough rolling (1070℃~1120℃): radial feed 2.2mm / s, completing 75% deformation, rolling expansion ratio 1.4~1.7; b. Secondary medium-temperature fine rolling (900℃~940℃): The feed is reduced to 0.8mm / s, and the last 10 seconds are spent with no feed for smooth rolling and shaping. The final rolling temperature is ≥850℃.

7. A forming apparatus for hot forging and expanding bearing rings from round steel, characterized in that, The device is manufactured using the molding method described in any one of claims 1-6; The device includes a round steel feeder (5), a steel cutter (6), an electric heating furnace (7), a material handling machine (8), a press (9), a ring rolling machine (10), a sizing machine (11), and an air-cooled chain machine (12), arranged sequentially and connected in the process direction; wherein, The press (9) is equipped with a forging die for high-temperature blanks at the stamping station; A conical positioning ring (14) is provided on the outer side of the roller (13) of the ring rolling machine (10), and a backing plate (15) adapted to the conical positioning ring (14) is detachably provided on the ring rolling machine (10).

8. The forming apparatus for hot forging and expanding bearing rings of round steel according to claim 7, characterized in that: The rolling wheel (13) includes a rolling wheel (131), a support wheel (132), and a signal wheel (133).

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