A hierarchical laser shock peening method for bearing inner ring arc surface raceway

Abstract

The application discloses a kind of hierarchical laser shock peening methods for bearing inner ring cambered raceway, comprising: calculating first laser peak power density and second laser peak power density;Constraining layer is applied to bearing raceway surface, and the optical axis of laser beam is incident along the surface normal direction of current machining position;In pre-impact stage, first laser peak power density is used to implement pre-impact to current machining position along predetermined machining track, and continuous pre-hardening layer is formed;In the same current machining position, continue to implement main impact with second laser peak power density, and form residual compressive stress field;After completion, move to next machining position until complete the coverage of bearing raceway area to be strengthened.The application calculates different levels of laser peak power density, sequentially implements low-energy pre-impact and high-energy main impact in the same machining position, forms continuous pre-hardening layer in surface layer and constructs deep residual compressive stress field in subsurface layer, effectively improves the contact fatigue life of bearing.

Description

Technical Field

[0001] This invention relates to the field of laser surface strengthening technology, and more specifically to a graded laser shock strengthening method for the inner ring arc surface raceway of a bearing. Background Technology

[0002] Rolling bearings play a crucial supporting and transmission role in aerospace, high-speed trains, precision machine tools, and high-end power equipment. During service, bearing raceways are subjected to high-frequency alternating Hertzian contact stress. Cracks often originate in the surface or subsurface layer of the raceway and further develop into failure modes such as wear, pitting, and spalling. Therefore, improving the damage resistance of the raceway surface and subsurface layer without compromising its surface integrity is a significant challenge in bearing strengthening.

[0003] Laser shock peening, with its advantages of being non-contact, having a high strain rate, large strengthening depth, and being precisely controllable, has been used to improve the residual compressive stress level and fatigue performance of metal components. However, for bearing raceways, especially concave inner ring raceways, directly using single-stage high-energy laser shock parameters can easily lead to excessive loading in local areas, resulting in deterioration of surface roughness, increased risk of local damage, or decreased strengthening uniformity. On the other hand, simply reducing the loading intensity can easily lead to insufficient subsurface strengthening depth.

[0004] Existing laser shock blasting techniques for curved surfaces primarily focus on improving uniformity by altering the incident angle, trajectory, orientation, or energy distribution. Similarly, existing laser shock blasting techniques for bearing raceways mainly concentrate on single-stage or single-process strengthening. For rolling contact surfaces like bearing raceways, which require both surface integrity and a stable residual compressive stress field in the subsurface layer, a coupled laser shock blasting technique that integrates surface pre-hardening and subsurface primary strengthening within the same process chain is still lacking.

[0005] Therefore, how to establish a coupled process that uses low-energy pre-impact to protect and pre-regulate the raceway surface, and then uses high-energy main impact to achieve secondary surface reinforcement under the same clamping, reference and high overlap trajectory conditions, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In view of the above problems, the present invention is proposed to provide a graded laser shock peening method for the inner ring arc surface raceway of a bearing that overcomes or at least partially solves the above problems, so as to solve the problem in the prior art that it is difficult to simultaneously take into account the surface integrity of the raceway and the subsurface strengthening depth.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a graded laser shock peening method for the raceway of the inner ring of a bearing, comprising: The dynamic impact threshold pressure of the bearing raceway material and the curvature compensation coefficient of the bearing inner ring arc surface are obtained; based on the constrained laser shock peak pressure model, combined with the first impact pressure coefficient corresponding to the pre-impact stage and the second impact pressure coefficient corresponding to the main impact stage, the first laser peak power density and the second laser peak power density are calculated. A constraint layer is applied to the surface of the bearing raceway, and the optical axis of the laser beam is incident along the surface normal direction of the current processing position; in the pre-impact stage, the current processing position is pre-impacted along the predetermined processing trajectory with the first laser peak power density to form a continuous pre-hardened layer; at the same current processing position, the main impact is continued with the second laser peak power density to form a residual compressive stress field; After completing the pre-impact and main impact at the current processing position, control the laser beam and / or bearing raceway to move to the next processing position according to the predetermined processing trajectory, and repeat the pre-impact and main impact until the area of ​​the bearing raceway to be reinforced is covered.

[0009] Furthermore, the first laser peak power density is less than the second laser peak power density, satisfying:

[0010] in, Indicates the first laser peak power density. This represents the second laser peak power density, expressed in GW / cm².

[0011] Furthermore, the first laser peak power density and the second laser peak power density are expressed by the following formula:

[0012]

[0013] 1.0 k 1<1.5 2.0 k 2<3.0 0.8 C r <0.95 in, C r Indicates the curvature compensation coefficient; P th Indicates the dynamic impact threshold pressure; α Indicates the laser-plasma coupling coefficient; Z Indicates the equivalent impact acoustic impedance; k 1 indicates the first impact pressure coefficient. k 2 indicates the second impact pressure coefficient.

[0014] Furthermore, in the pre-impact stage, a first laser peak power density of 1.0 GW / cm² to 3.0 GW / cm², a pulse width of 5 ns to 10 ns, and a first spot diameter of 1 mm to 2 mm are used to form a continuous pre-hardened zone within a range of 5 μm to 15 μm below the bearing raceway surface.

[0015] Furthermore, during the main impact phase, a second laser peak power density of 5.0 GW / cm² to 10.0 GW / cm², a pulse width of 10 ns to 30 ns, and a second spot diameter of 2 mm to 4 mm are used to create a residual compressive stress field within a range of 50 μm to 300 μm from the bearing raceway surface.

[0016] Furthermore, during the pre-impact phase and the main impact phase, the overlap rate of the light spots of adjacent pulses is 40% to 70%.

[0017] Furthermore, the constraint layer is a flowing water constraint layer with a thickness of 0.5 mm to 2.0 mm, a flow rate of 1 L / min to 5 L / min, and a temperature of 18 °C to 25 °C.

[0018] Furthermore, the dynamic impact threshold pressure of the bearing raceway material is the Hugon elastic limit of the bearing raceway material, or the dynamic impact threshold pressure obtained through impact test calibration, numerical inversion, or literature conversion.

[0019] Furthermore, the laser beam adopts a single-pulse mode or a double-pulse mode during the main impact phase; when the double-pulse mode is adopted, the time interval between the two sub-pulses is 1ns to 5ns.

[0020] Furthermore, the pre-impact and main impact at the current processing position are implemented within a cycle time of 100ms.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a graded laser shock blasting method for the raceway of the inner ring of a bearing, which has the following beneficial effects: 1. Eliminate the focusing effect of curved surfaces and ensure processing safety.

[0022] This invention innovatively introduces a curvature compensation coefficient, combined with a constrained laser shock peak pressure model for parameter calculation. This effectively counteracts the concave focusing effect of the bearing inner ring arc raceway during laser processing, avoiding surface ablation or microcracks caused by excessively high local energy density, and significantly improving the safety of the processing and the surface quality of the workpiece.

[0023] 2. Strengthen synergistic regulation in a tiered manner, taking into account both surface and deep layer performance.

[0024] By employing a graded strategy of "low-energy pre-impact + high-energy main impact," this invention overcomes the limitations of traditional single-impact processes. The pre-impact stage forms a continuous pre-hardened layer on the surface, improving the material's resistance to plastic deformation; the main impact stage further constructs a deep residual compressive stress field in the subsurface layer. This synergistic strengthening mechanism effectively improves the bearing's contact fatigue life and service reliability.

[0025] 3. Precise and controllable process parameters improve manufacturing consistency.

[0026] This invention sets the impact pressure coefficient based on the material's dynamic impact threshold pressure, achieving quantitative and precise control of process parameters. Compared to traditional trial-and-error methods, this invention significantly improves the stability and repeatability of laser shock peening processes, making it particularly suitable for the mass production of high-end precision bearings and possessing significant industrial application value. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0028] Figure 1 This is a flowchart of a graded laser shock blasting method for the raceway of the inner ring of a bearing, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the graded laser shock blasting method for the inner ring arc raceway of a bearing provided in an embodiment of the present invention. Figure 3 This is a diagram showing the distribution of residual compressive stress along the depth direction after treatment, provided in an embodiment of the present invention. Figure 4 This is a diagram showing the distribution of residual compressive stress along the treatment trajectory after treatment, provided in an embodiment of the present invention. Figure 5 This is a diagram showing the surface roughness along the direction perpendicular to the guide rail after processing, as provided in an embodiment of the present invention. Detailed Implementation

[0029] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention discloses a graded laser shock peening method for the raceway of the inner ring of a bearing, referring to... Figure 1 As shown, it includes: The dynamic impact threshold pressure of the bearing raceway material and the curvature compensation coefficient of the bearing inner ring arc surface are obtained; based on the constrained laser shock peak pressure model, combined with the first impact pressure coefficient corresponding to the pre-impact stage and the second impact pressure coefficient corresponding to the main impact stage, the first laser peak power density and the second laser peak power density are calculated. A constraint layer is applied to the surface of the bearing raceway, and the optical axis of the laser beam is incident along the surface normal direction of the current processing position; in the pre-impact stage, the current processing position is pre-impacted along the predetermined processing trajectory with a first laser peak power density to form a continuous pre-hardened layer; at the same current processing position, the main impact is continued with a second laser peak power density to form a residual compressive stress field; After completing the pre-impact and main impact at the current processing position, control the laser beam and / or bearing raceway to move to the next processing position according to the predetermined processing trajectory, and repeat the pre-impact and main impact until the area of ​​the bearing raceway to be reinforced is covered.

[0031] This embodiment uses the inner ring arc raceway of a certain type of aero-engine main shaft bearing (made of M50 high-temperature bearing steel) as the machining object. First, the parameters are calibrated and set to obtain the dynamic impact threshold pressure (HEL) of the M50 bearing steel material, and the radius of curvature of the inner ring raceway is measured to calculate the curvature compensation coefficient. Based on the constrained laser shock peak pressure model, the pre-impact pressure coefficient and the main impact pressure coefficient are set. Then, the pre-impact and main impact are performed sequentially. Under the constraint of flowing water, the pre-impact is first performed along the predetermined trajectory of the raceway with a lower peak power density and a smaller spot size, forming a continuous pre-hardened zone on the raceway surface. Then, under the same clamping state and the same coordinate reference, the main impact is performed along the same or highly overlapping trajectory as the pre-impact trajectory with a higher peak power density and a larger spot size, so that the main impact spot covers the continuous pre-hardened zone formed by the pre-impact in the transverse direction, thereby maintaining the integrity of the raceway surface while stably introducing residual compressive stress into the subsurface layer of the raceway. Finally, the laser beam and / or bearing raceway are controlled to move to the next processing position according to the predetermined processing trajectory, and the pre-impact and main impact are repeated until the area of ​​the bearing raceway to be reinforced is covered.

[0032] This embodiment includes a pre-impact, main impact, and process parameter coordinated control process. In the pre-impact stage, a lower peak power density and a smaller spot size are applied to the raceway surface to form a continuous pre-hardened zone near the raceway surface. In the main impact stage, a higher peak power density and a larger spot size are applied to the raceway region along the same or highly overlapping trajectory, causing the stress wave generated by the main impact to continue to propagate to the subsurface layer and form a residual compressive stress field.

[0033] Reference Figure 2 The diagram illustrates the process of graded strengthening of a material matrix using laser beams of varying energies. The laser source is the initiating device for generating the laser beam; after emission, the beam is transmitted and focused through a series of optical elements (including lenses and mirrors). A double-arrow at the end of the optical path indicates that the laser beam moves horizontally during processing. The rectangular block below represents the metal workpiece being processed. The material surface is shown with two stages of processing, from left to right: pre-impact uses a low-energy laser to act on the material surface, forming a pre-hardened area; main impact uses a high-energy laser to act on the pre-impact-controlled area, creating a deeper residual compressive stress field within the material. By combining pre-impact and main impact, the strengthening effect of the secondary surface layer can be improved while maintaining surface integrity. Figure 2 This clearly demonstrates a graded laser shock blasting strategy of "weak first, strong later": first, surface pre-hardening is performed using a low-energy laser, then deep strengthening is performed using a high-energy laser, and finally a beneficial residual compressive stress layer is constructed inside the material, thereby improving the mechanical properties of the material.

[0034] The specific implementation process is described in detail below: First, parameter calibration and settings are performed.

[0035] This embodiment focuses on the raceway of the inner ring of a high-temperature bearing steel in an M50 type of aero-engine. This raceway is a typical concave surface. To ensure consistent parameter setting logic, the dynamic impact threshold pressure P of the material under this operating condition is first determined. th The coupling parameters under water-constrained conditions were calibrated.

[0036] The dynamic impact threshold pressure of the bearing raceway material is either the Hugon elastic limit of the bearing raceway material or the dynamic impact threshold pressure obtained through impact testing, numerical inversion, or literature calculation. In this embodiment, the previously calibrated dynamic impact threshold pressure P is used. th =1.10GPa, laser-plasma coupling coefficient α=0.10, equivalent impact acoustic impedance Z=3.2×105g / (cm²·s), concave surface curvature compensation coefficient Cr=0.90.

[0037] After setting the parameters, pre-impact and main impact are performed on each processing position in sequence according to the predetermined processing trajectory.

[0038] The first and second laser peak power densities are determined according to the following formulas:

[0039]

[0040] in, Indicates the first laser peak power density. This represents the second laser peak power density, expressed in GW / cm². C r Indicates the curvature compensation coefficient; P th Indicates the dynamic impact threshold pressure; α Indicates the laser-plasma coupling coefficient; Z Indicates the equivalent impact acoustic impedance; k 1 indicates the first impact pressure coefficient. k 2 indicates the second impact pressure coefficient.

[0041] In this embodiment, the peak power density of the first laser during the pre-impact stage is less than the peak power density of the second laser during the main impact stage, and satisfies the following:

[0042] In this embodiment, the impact pressure coefficients of the pre-impact stage and the main impact stage satisfy: 1.0 k 1<1.5 2.0 k 2<3.0 The formula is expressed as follows:

[0043]

[0044] In this embodiment, the target peak pressures of the pre-impact stage and the main impact stage are defined as follows: and ,satisfy:

[0045]

[0046] in, This indicates the target peak impact pressure during the pre-impact phase. The target peak impact pressure during the main impact phase is represented by GPa.

[0047] In this embodiment, the constrained laser shock peak pressure model is used to estimate the peak pressure of the laser-induced plasma shock wave acting on the raceway surface under the constraint layer condition. Its expression is as follows:

[0048] in, Indicates the first i Peak surface pressure under staged constrained laser shock, in GPa; Indicates the first iThe peak power density of the laser at each stage, expressed in GW / cm².

[0049] For the concave raceway of the bearing inner ring in this embodiment, the curvature compensation coefficient satisfies: 0.8 C r <0.95 The calculation formula is:

[0050] in, This represents the surface focusing effect coefficient, which is used to characterize the degree of amplification of the residual compressive stress response of the concave curved raceway relative to a planar reference specimen of the same material under the same laser shock parameters. The absolute value of the peak residual compressive stress formed in a planar reference specimen of the same material under the same laser shock parameters; It represents the absolute value of the peak residual compressive stress formed on the concave raceway specimen under the same laser shock parameters.

[0051] The pre-impact stage employs a first laser peak power density of 1.0 GW / cm² to 3.0 GW / cm², a pulse width of 5 ns to 10 ns, and a first spot diameter of 1 mm to 2 mm to form a continuous pre-hardened zone within a range of 5 μm to 15 μm below the raceway surface.

[0052] In this embodiment, the first impact pressure coefficient k1 = 1.25 is selected. Based on the above formula, specific calculations are performed, and the first laser peak power density I1 is approximately 1.8 GW / cm². Considering the discrete setting capability of the equipment, the first laser peak power density is set to 1.8 GW / cm², the pulse width is 8 ns, the spot diameter is 1.5 mm, the repetition frequency is 30 Hz, and the overlap rate of adjacent pulse spots is set to 50%. During the processing, the laser optical axis is always aligned with the surface normal of the current processing point by means of a normal follower mechanism, and a spiral trajectory is used to scan along the roller arc surface.

[0053] Under the aforementioned parameters, controlled high-strain-rate plastic deformation occurred on the raceway surface, resulting in a significant increase in dislocation density and the formation of a continuous pre-hardened layer approximately 5 μm to 12 μm below the workpiece surface. The microhardness of this region was measured to be approximately 118% of the substrate, and the average surface roughness Ra of the raceway after surface treatment was no higher than 0.25 μm. No obvious melting, spalling, or surface microcracks were observed.

[0054] After the pre-impact, under the same clamping condition and coordinate reference, the system switches to the main impact stage within 80ms. During the main impact stage, a second laser peak power density of 5.0GW / cm² to 10.0GW / cm², a pulse width of 10ns to 30ns, and a second spot diameter of 2mm to 4mm are used to create a residual compressive stress field within a range of 50μm to 300μm from the bearing raceway surface.

[0055] In this embodiment, the second impact pressure coefficient k2 = 2.66 is selected. Based on the parameter setting formula, the second laser peak power density I2 is calculated to be approximately 8.1 GW / cm². In actual processing, the second laser peak power density is set to 8.1 GW / cm², the pulse width is 20 ns, the spot diameter is 3.0 mm, the main impact trajectory covers the pre-impact trajectory, and the overlap rate of adjacent pulse spots is also set to 50%. The peak power density ratio of the two stages is approximately 1:4.5.

[0056] In this embodiment, the main impact adopts a dual-pulse mode, with a time interval of 3ns between the two sub-pulses. This dual-pulse structure is used to extend the time of the confined plasma pressure load in a single main impact; while the 80ms stage switching time is used to ensure that the pre-impact and main impact are completed under the same clamping, the same trajectory, and the same water confinement conditions, and is not used to explain the plasma transient shielding mechanism.

[0057] This embodiment uses a lower first laser peak power density to pre-impact the raceway surface, forming a pre-hardened layer on the material surface without causing significant macroscopic damage. A higher second laser peak power density is then used for the main impact on the same or overlapping trajectory, ensuring the impact load primarily acts on the raceway subsurface, thereby creating a residual compressive stress field that helps suppress the initiation and propagation of rolling contact fatigue cracks. The purpose is not simply to perform two laser impacts, but to ensure the following linkage occurs simultaneously: (1) The peak power density of the first laser in the pre-impact stage is lower than that of the second laser in the main impact stage; (2) The diameter of the first spot in the pre-impact stage is smaller than the diameter of the second spot in the main impact stage; (3) The main impact trajectory is the same as or highly overlaps with the pre-impact trajectory; (4) The main impact spot covers the continuous pre-hardened zone formed by the pre-impact in the transverse direction; (5) The two stages are carried out continuously under the same clamping state and the same coordinate reference.

[0058] Through the above-mentioned linkage, the pre-impact is no longer just an independent strengthening step, but exists as a surface pre-regulation step before the main impact. Its role is to preferentially improve the bearing state of the raceway surface to the subsequent main impact. The main impact no longer acts in isolation on the unregulated raceway surface, but introduces the residual compressive stress more stably into the raceway sub-surface on the basis of the continuous pre-hardened zone formed by the pre-impact.

[0059] Secondly, implement coordinated control of process parameters.

[0060] Throughout the entire processing in this embodiment, the raceway surface is continuously covered with a 1.0 mm thick flowing water constraint layer at a water flow rate of 2 L / min and a temperature controlled at 20℃±2℃. The flowing water constraint layer is used to stabilize the impact loading and promptly remove air bubbles and debris. By controlling the peak power density ratio, trajectory overlap, and spot overlap rate, the process matching between the formation of the pre-hardened layer and the deep reinforcement of the main impact is ensured.

[0061] Finally, after completing the pre-impact and main impact at the current processing position or trajectory segment, the laser beam and / or the bearing inner ring are controlled to move to the next processing position according to the predetermined processing trajectory, and the pre-impact and main impact are repeated until the raceway area to be strengthened is covered. The next processing position is determined by the predetermined processing trajectory, the spot diameter, and the spot overlap rate, rather than by a fixed time interval.

[0062] To further demonstrate the effectiveness of the graded laser shock peening strategy in improving the residual compressive stress and surface integrity of the raceway subsurface, this embodiment conducts residual stress and surface roughness tests on the treated raceway.

[0063] Reference Figure 3 The diagram shown illustrates the distribution of residual compressive stress along the depth direction. Figure 3 The residual compressive stress in the middle raceway exhibits a distribution characteristic of first increasing and then gradually decreasing along the depth direction. The peak value of the residual compressive stress appears at about 100 μm from the surface, indicating that the main impact can effectively introduce the compressive stress into the secondary surface layer of the raceway on the basis of the pre-hardened surface layer formed by the pre-impact.

[0064] Reference Figure 4 As shown, the distribution of residual compressive stress along the transverse position of the treatment trajectory is illustrated. The residual compressive stress in the transverse position of the treatment area remains at a high level in the central region and gradually decreases towards both sides, indicating that the main impact area can cover the pre-hardened area formed by the pre-impact and form a relatively continuous transverse residual compressive stress distribution.

[0065] Reference Figure 5As shown, the result diagram of surface roughness along the direction perpendicular to the guide rail is displayed. The surface roughness of the raceway after processing fluctuates less along the lateral position, indicating that the graded impact method in this embodiment can maintain the integrity of the raceway surface well while introducing residual compressive stress in the subsurface layer.

[0066] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A graded laser shock peening method for the raceway of the inner ring of a bearing, characterized in that, include: The dynamic impact threshold pressure of the bearing raceway material and the curvature compensation coefficient of the bearing inner ring arc surface are obtained; based on the constrained laser shock peak pressure model, combined with the first impact pressure coefficient corresponding to the pre-impact stage and the second impact pressure coefficient corresponding to the main impact stage, the first laser peak power density and the second laser peak power density are calculated. A constraint layer is applied to the surface of the bearing raceway, and the optical axis of the laser beam is incident along the surface normal direction of the current processing position; in the pre-impact stage, the current processing position is pre-impacted along the predetermined processing trajectory with the first laser peak power density to form a continuous pre-hardened layer; at the same current processing position, the main impact is continued with the second laser peak power density to form a residual compressive stress field; After completing the pre-impact and main impact at the current processing position, control the laser beam and / or bearing raceway to move to the next processing position according to the predetermined processing trajectory, and repeat the pre-impact and main impact until the area of ​​the bearing raceway to be reinforced is covered.

2. The method as described in claim 1, characterized in that, The first laser peak power density is less than the second laser peak power density, satisfying: in, Indicates the first laser peak power density. This represents the second laser peak power density, expressed in GW / cm².

3. The method as described in claim 2, characterized in that, The first laser peak power density and the second laser peak power density are expressed by the following formulas: 1.0< k 1<1.5 2.0< k 2<3.0 0.8< C r <0.95 in, C r Indicates the curvature compensation coefficient; P th Indicates the dynamic impact threshold pressure; α Indicates the laser-plasma coupling coefficient; Z Indicates the equivalent impact acoustic impedance; k 1 indicates the first impact pressure coefficient. k 2 indicates the second impact pressure coefficient.

4. The method as described in claim 3, characterized in that, During the pre-impact stage, a first laser peak power density of 1.0 GW / cm² to 3.0 GW / cm², a pulse width of 5 ns to 10 ns, and a first spot diameter of 1 mm to 2 mm are used to form a continuous pre-hardened zone within a range of 5 μm to 15 μm below the bearing raceway surface.

5. The method as described in claim 3, characterized in that, During the main impact phase, a second laser peak power density of 5.0 GW / cm² to 10.0 GW / cm², a pulse width of 10 ns to 30 ns, and a second spot diameter of 2 mm to 4 mm are used to create a residual compressive stress field within a range of 50 μm to 300 μm from the bearing raceway surface.

6. The method as described in claim 1, characterized in that, During the pre-impact and main impact phases, the overlap rate of adjacent pulse spots is 40% to 70%.

7. The method as described in claim 1, characterized in that, The constraint layer is a flowing water constraint layer with a thickness of 0.5 mm to 2.0 mm, a flow rate of 1 L / min to 5 L / min, and a temperature of 18 °C to 25 °C.

8. The method as described in claim 1, characterized in that, The dynamic impact threshold pressure of the bearing raceway material is the Hugon elastic limit of the bearing raceway material, or the dynamic impact threshold pressure obtained by impact test calibration, numerical inversion or literature conversion.

9. The method as described in claim 1, characterized in that, The laser beam uses either a single-pulse mode or a double-pulse mode during the main impact phase; when using the double-pulse mode, the time interval between the two sub-pulses is 1 ns to 5 ns.

10. The method as described in claim 1, characterized in that, The pre-impact and main impact at the current processing position are implemented within a cycle time of 100ms.

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