CN117512323A - Laser impact combined strengthening process for improving contact fatigue performance of bearing - Google Patents
Laser impact combined strengthening process for improving contact fatigue performance of bearing Download PDFInfo
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- CN117512323A CN117512323A CN202311412893.6A CN202311412893A CN117512323A CN 117512323 A CN117512323 A CN 117512323A CN 202311412893 A CN202311412893 A CN 202311412893A CN 117512323 A CN117512323 A CN 117512323A
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- 238000005728 strengthening Methods 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 86
- 239000010410 layer Substances 0.000 claims abstract description 92
- 230000035939 shock Effects 0.000 claims abstract description 61
- 238000003754 machining Methods 0.000 claims abstract description 26
- 239000011241 protective layer Substances 0.000 claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 238000010521 absorption reaction Methods 0.000 claims description 17
- 238000012545 processing Methods 0.000 claims description 10
- 239000002390 adhesive tape Substances 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- 238000005516 engineering process Methods 0.000 claims description 5
- 238000007517 polishing process Methods 0.000 claims description 3
- 238000007781 pre-processing Methods 0.000 claims description 3
- 230000003014 reinforcing effect Effects 0.000 claims 1
- 239000002344 surface layer Substances 0.000 abstract description 10
- 238000005096 rolling process Methods 0.000 abstract description 7
- 238000011282 treatment Methods 0.000 description 12
- 238000009826 distribution Methods 0.000 description 9
- 230000002787 reinforcement Effects 0.000 description 8
- 238000005498 polishing Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000002679 ablation Methods 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 3
- 238000000608 laser ablation Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 230000003746 surface roughness Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000005480 shot peening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D10/00—Modifying the physical properties by methods other than heat treatment or deformation
- C21D10/005—Modifying the physical properties by methods other than heat treatment or deformation by laser shock processing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races
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- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Optics & Photonics (AREA)
- Laser Beam Processing (AREA)
- Rolling Contact Bearings (AREA)
Abstract
The invention provides a laser impact combined strengthening process for improving contact fatigue performance of a bearing, which comprises the steps of reserving a machining allowance layer on the surface of a raceway of the bearing; then a protective layer is attached; then carrying out large-spot laser impact to form a first plastic strengthening layer; further carrying out microscale laser shock to form a second plastic strengthening layer on the shallow surface layer of the first plastic strengthening layer; and finally removing the reserved machining allowance layer. According to the process, a first plastic strengthening layer with large depth is formed on the surface of a raceway area through large-spot laser shock, on the basis, a second shallow plastic strengthening layer is formed on the surface through microscale laser shock, the performance of a strengthening area can be improved through secondary strengthening, and more importantly, the smoothness and plastic deformation uniformity of the plastic strengthening layer can be optimized; and removing and finishing the reinforced area by a certain thickness to ensure that the surface finish of the raceway meets the related technical requirements, thereby finally and obviously improving the rolling contact fatigue performance of the bearing.
Description
Technical Field
The invention relates to the technical field of laser shock reinforcement, in particular to a laser shock combined reinforcement process for improving contact fatigue performance of a bearing.
Background
High-end bearings such as aero-engines, gas turbines, steam turbines, high-speed rails and the like are continuously improved along with the continuous improvement of performance technical indexes of the whole equipment, and the performance requirements of the bearings are developing to high DN values, high-temperature environments, heavy loads, long service lives, high reliability and the like. The bearing is used as a supporting and transmitting part of the whole rotor system, so that the faults of abrasion scratch, contact fatigue fracture, clamping shaft, shaft locking and the like easily occur, and the operation safety of the rotating system equipment is seriously influenced. According to the statistical data result of the aviation industry failure analysis center in China, the failure rate of the aviation bearing in the domestic aviation bearing failure case, which is directly caused by abrasion, contact fatigue and the like, is about more than 20 percent in recent 10 years.
During the working process of the bearing, the roller rolls on the raceway at a high speed and with heavy load, and the contact fatigue failure of the raceway surface material cannot be avoided, and especially when the raceway surface is damaged by abrasion, scratch and the like, the crack initiation and fracture process of the contact fatigue can be further accelerated. Therefore, how to effectively modify the bearing raceway surface and improve the rolling contact fatigue performance thereof is important.
The laser shock peening technique (Laser Shock Peening, LSP) is a surface plastic peening technique by short pulse (nanosecond) high power (GW/cm) 2 The level) laser interacts with substances to generate high-pressure (GPa magnitude) plasma shock waves, and the mechanical effect of the shock waves is utilized to enable the surface layer of the metal material to generate plastic deformation, so that residual compressive stress is formed, microstructure is improved, and the fatigue performance of the material is remarkably improved.
However, as in the conventional mechanical shot peening, a large number of plastic deformation pits are formed in the surface treatment area of the material, which results in an increase in the surface roughness of the material and the uniformity of plastic deformation cannot be ensured. For the high-end bearing, the raceway surface finish is extremely high because the raceway works under high-speed and heavy-load conditions for a long time, and the contact fatigue failure of the bearing raceway can be accelerated due to large surface roughness or uneven material hardness.
Therefore, the application of laser shock peening to the raceway portion of the high-end bearing is urgent to provide an innovative process which is feasible in engineering and has multiple aspects, on one hand, the degree and depth of plastic deformation are required to be ensured, and on the other hand, the problems of surface roughness increase and plastic deformation uniformity are required to be eliminated, so that the rolling contact fatigue performance of the bearing is remarkably improved.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention aims at:
in a first aspect, a laser shock combined strengthening process for improving contact fatigue performance of a bearing is provided, and is characterized by comprising the following steps:
s1, preprocessing: reserving a machining allowance layer on the surface of a raceway of the bearing, wherein the thickness of the raceway is d, and the thickness of the machining allowance layer is d 0 ；
S2, sticking protection: attaching an absorption protective layer on the surface of a raceway of the bearing, and applying a constraint layer on the surface of the absorption protective layer;
s3, large-spot laserImpact: the raceway area is reinforced by large-spot laser shock to form a raceway area with depth d 1 D 1 ＞d 0 ；
S4, micro-scale laser shock: directly applying a constraint layer on the surface of the first plastic strengthening layer without absorbing a protective layer, and adopting microscale laser to impact and strengthen a raceway area to form a depth d 2 D 1 ＞d 2 ＞d 0 ；
S5, removing the reserved machining allowance layer.
With reference to the first aspect, in one implementation, the depth d of the first plastic strengthening layer 1 The thickness of the roller path is 0.1 to 0.3 times of the thickness d.
With reference to the first aspect, in one implementation, the energy of the large-spot laser impact is greater than the energy of the micro-scale laser impact; the diameter of the light spot impacted by the large-light-spot laser is larger than that of the light spot impacted by the microscale laser; the pulse width of the large-spot laser impact is larger than that of the microscale laser impact; the repetition frequency of the large-spot laser shock is smaller than that of the micro-scale laser shock.
With reference to the first aspect, in one implementation manner, the energy of the large-spot laser impact is 2-25J, the spot diameter is 1-3 mm, the pulse width is 20-50 ns, and the repetition frequency is 1-20 Hz.
With reference to the first aspect, in one implementation manner, the depth of the first plastic strengthening layer is 1-2 mm, so as to form a plastic strengthening layer with a high surface level and a large section depth.
With reference to the first aspect, in one implementation, the energy of the micro-scale laser impact is 10-500 mJ, the spot diameter is 100-500 μm, the pulse width is 5-10 ns, and the repetition frequency is 100-1000 Hz.
With reference to the first aspect, in one implementation, the depth of the second plastic strengthening layer is 0.4 to 0.6mm. The mechanical property and the microstructure uniformity of the plastic strengthening layer are obviously improved.
With reference to the first aspect, in one implementation manner, the absorption protection layer is a black adhesive tape; the constraint layer is a water curtain formed by applying deionized water.
With reference to the first aspect, in one implementation manner, the removing the reserved machining allowance layer uses a finish grinding and polishing process to machine and remove the machining allowance layer on the surface of the raceway.
In a second aspect, a bearing processing technology is provided, which is characterized in that: comprising the laser shock combining strengthening process for improving the contact fatigue performance of the bearing in any implementation manner of the first aspect.
As described above, the laser shock combined strengthening process for improving the contact fatigue performance of the bearing at least comprises the following beneficial effects: forming a first plastic strengthening layer with large depth on the surface of the raceway area through large-spot laser impact, forming a second shallower plastic strengthening layer on the surface through micro-scale laser impact on the basis, and improving the performance of the strengthening area through secondary strengthening, and more importantly, optimizing the smoothness and plastic deformation uniformity of the plastic strengthening layer; and removing and finishing the reinforced area by a certain thickness to ensure that the surface finish of the raceway meets the related technical requirements, thereby finally and obviously improving the rolling contact fatigue performance of the bearing.
Description of the drawings:
FIG. 1 is a schematic illustration of the process of the present invention for bearing machining; wherein 1 is a bearing raceway, 2 is an absorption protection layer, 3 is a constraint layer, 4 is a large-spot laser shock wave, and 5 is a microscale laser shock wave.
FIG. 2 is a process flow diagram of the present invention;
FIG. 3 is a graph showing the depth distribution of residual compressive stress under different strengthening processes;
FIG. 4 is a view of a transmission electron microscope of a surface microstructure under different strengthening processes (wherein a is an original state, b is a strengthening result of a conventional process, and c is a strengthening result of a laser shock combined strengthening process according to the present invention);
FIG. 5 shows the results of contact fatigue performance tests under different strengthening processes.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be understood that the preferred embodiments are presented by way of illustration only and not by way of limitation.
Firstly, the technical scheme of the invention provides a laser impact combined strengthening process for improving the contact fatigue performance of a bearing, which comprises the following steps:
s1, preprocessing: reserving a machining allowance layer on the surface of a raceway of the bearing, wherein the thickness of the raceway is d, and the thickness of the machining allowance layer is d 0 The method comprises the steps of carrying out a first treatment on the surface of the And the processing redundancy is reserved for the post-finishing treatment.
S2, sticking protection: and (3) attaching an absorption protective layer on the surface of the raceway of the bearing, and applying a constraint layer on the surface of the absorption protective layer.
S3, large-spot laser impact: the raceway area is reinforced by large-spot laser shock to form a raceway area with depth d 1 D 1 ＞d 0 The method comprises the steps of carrying out a first treatment on the surface of the The depth of the first plastic strengthening layer is millimeter level, namely, a strengthening hardening layer with large depth is obtained, and residual compressive stress and hardness with high surface amplitude and gradient distribution are formed on the depth.
S4, micro-scale laser shock: directly applying a constraint layer on the surface of the first plastic strengthening layer, and strengthening the raceway area by adopting microscale laser shock without attaching an absorption protection layer to form a depth d 2 D 1 ＞d 2 ＞d 0 The method comprises the steps of carrying out a first treatment on the surface of the Namely, a second plastic strengthening layer is formed in the shallow surface layer of the first plastic strengthening layer, so that the grain structure of the surface layer is thinned to a high degree, the surface distribution of residual compressive stress, hardness and the like is more uniform, and the uniformity of surface strengthening/hardening is ensured.
S5, removing the reserved processing allowance layer, wherein d is 1 ＞d 2 ＞d 0 Thus, after removal of the work balance layer, the raceway reinforcement region retains only the first plastic reinforcement layer anda second plastic strengthening layer is formed in a shallow surface layer of the first plastic strengthening layer and the surface may be treated to achieve a desired surface finish.
It should be further noted that large-spot laser shock and microscale laser shock are relative concepts based on the laser shock technique to distinguish between the laser shock technique and the enhancement depth. The large-spot laser impact is deeper than the plastic strengthening layer formed by micro-scale laser impact, and the light spot is larger.
In some embodiments, the depth d of the first plastic strengthening layer 1 The thickness of the roller path is 0.1 to 0.3 times of the thickness d. The strengthening depth of the proportion has good strengthening effect and does not cause the integral deformation of the bearing due to the too large plastic deformation.
In some embodiments, the energy of the large spot laser shock is greater than the energy of the microscale laser shock; the diameter of the light spot impacted by the large-light-spot laser is larger than that of the light spot impacted by the microscale laser; the pulse width of the large-spot laser impact is larger than that of the microscale laser impact; the repetition frequency of the large-spot laser shock is smaller than that of the micro-scale laser shock. The high-depth strengthening/hardening layer can be obtained through the combined treatment of the high-energy, large-light-spot, long-pulse-width, low-heavy-frequency and small-energy, small-light-spot, short-pulse-width and high-heavy-frequency process methods, the uniformity of surface strengthening/hardening can be ensured, and the contact fatigue performance is improved from two factors.
On the one hand, on the other hand, on the basis of energy conservation consideration and on the other hand, on the basis of practical application of bearing processing, relevant parameters of large-spot laser impact are required to be optimized, and the hardening enhancement effect is guaranteed, and meanwhile, excessive energy and resources are not wasted, so that in some embodiments, the energy of the large-spot laser impact is 2-25J, the spot diameter is 1-3 mm, the pulse width is 20-50 ns, and the repetition frequency is 1-20 Hz. In some embodiments, the first plastic strengthening layer has a depth of 1 to 2mm.
As described above, the reinforcement hardening effect is ensured without wasting excessive energy and resources, so that in some embodiments, the micro-scale laser impact energy is 10-500 mJ, the spot diameter is 100-500 μm, the pulse width is 5-10 ns, and the repetition frequency is 100-1000 Hz. In some embodiments, the depth of the second plastic strengthening layer is 0.4-0.6 mm, significantly improving the mechanical properties and microstructure uniformity of the plastic strengthening layer.
In some embodiments, the absorptive protective layer is a black tape; the constraint layer is a water curtain formed by applying deionized water.
In some embodiments, the removing the reserved machining allowance layer uses a finish grinding and polishing process to machine and remove the machining allowance layer on the surface of the raceway. And removing and finishing the reinforced area with a certain thickness, removing a damaged layer on the surface of the material, and ensuring that the surface finish of the rollaway nest meets the related technical requirements.
Secondly, a bearing processing technology is also provided, comprising the laser shock combined strengthening technology for improving the contact fatigue performance of the bearing in any embodiment, preferably, the laser shock combined strengthening technology is arranged between bearing machining processes and between rough grinding and fine grinding, so that the application of the laser shock strengthening of the roller path can be realized, the requirements of the surface finish of the roller path and the like can be ensured, and the engineering applicability is good.
The present invention will be described in detail with reference to specific exemplary examples. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, as many insubstantial modifications and variations are within the scope of the invention as would be apparent to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.
Example 1: the main bearing of an aeroengine is taken as an example for carrying out a combined strengthening process, and the main bearing is made of M50 steel, the width of a roller path is 30mm, and the thickness of the roller path is 10mm. The specific implementation process is as follows:
(1) Cutting, turning and other mechanical processing on the bearing blank, and coarse grinding in a grinder to reach the thickness of the roller pathStopping when the dimension is 10.2mm, and reserving the thickness d 0 A machining allowance layer of 0.2 mm.
(2) A black adhesive tape is used as an absorption protective layer and is adhered to the surface of a bearing roller path, then the bearing is fixed on a 5-axis robot arm, and deionized water flow is applied to the roller path area through a universal joint water pipe, so that a water curtain of 1-2 mm is formed on the surface of the roller path and is used as a constraint layer.
(3) The bearing roller way faces the fixed light path outlet by adjusting the gesture of the robot arm, then pulse laser parameter setting is carried out by a laser impact strengthening integrated control system, the laser energy is 25J, the spot diameter is 3mm, the pulse width is 50ns, the repetition frequency is 20Hz, and the laser power density is 7.08GW/cm at the moment 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(4) Starting a traditional laser shock strengthening system, treating a bearing raceway area, and forming depth d in the raceway area 1 The first plastic strengthening layer with the thickness of 2mm is prefabricated with high-amplitude residual compressive stress, the maximum residual compressive stress can reach more than 700MPa, and the microhardness can be improved by more than 20%.
(5) And fixing the reinforced bearing on a micro-scale laser shock reinforcement system, tearing off the black adhesive tape used in the previous process, and avoiding adopting any absorption protection layer.
(6) On a microscale laser shock strengthening system, pulse laser parameter setting is carried out, the laser energy is 500mJ, the diameter of a light spot is 500 mu m, the pulse width is 10ns, the repetition frequency is 1000Hz, and the laser power density is 25.48GW/cm 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(7) The bearing roller path is subjected to microscale laser shock strengthening treatment in a water-light same path mode, laser ablation can occur on the surface of the roller path, and the ablation layer is several micrometers, but can be at depth d 2 Form high degree grain refinement within 600 μm, even reach nanocrystalline structure level, and form high uniform plastic deformation, so that the distribution of mechanical properties such as residual compressive stress, hardness, etc. is more uniform, and the numerical fluctuation value is controlled within 10%.
(8) Finally, carrying out technological treatments such as fine grinding, polishing and the like on the bearing roller path, and removing the machining allowance d 0 The thickness d of the bearing roller path is 10mm, and the surface finish and the like also meet the related technical requirements.
(9) The combined strengthening process method forms a plastic strengthening/hardening layer with large depth through a large-energy, large-light-spot, long-pulse width and low-repetition-frequency process method; forming a plastic strengthening/hardening layer with high uniformity on a shallow surface layer by a small-energy, small-light-spot, short-pulse width and high-repetition frequency process method; and then the surface finish degree is ensured to meet the related technical requirements through working procedures such as fine grinding, polishing and the like, so that the rolling contact fatigue performance of the bearing is improved more remarkably.
Example 2: the main bearing of an aeroengine is taken as an example for carrying out a combined strengthening process, and the main bearing is made of M50 steel, the width of a roller path is 30mm, and the thickness of the roller path is 10mm. The specific implementation process is as follows:
(1) Cutting, turning and other mechanical processing on the bearing blank, coarse grinding in grinder to thickness of 10.2mm, stopping and reserving thickness d 0 A machining allowance layer of 0.2 mm.
(2) A black adhesive tape is used as an absorption protective layer and is adhered to the surface of a bearing roller path, then the bearing is fixed on a 5-axis robot arm, and deionized water flow is applied to the roller path area through a universal joint water pipe, so that a water curtain of 1-2 mm is formed on the surface of the roller path and is used as a constraint layer.
(3) The bearing roller way faces the fixed light path outlet by adjusting the gesture of the robot arm, and then pulse laser parameter setting is carried out by a laser impact strengthening integrated control system, the laser energy is 2J, the light spot diameter is 1mm, the pulse width is 20ns, the repetition frequency is 1Hz, and the laser power density is 12.74GW/cm at the moment 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(4) Starting a traditional laser shock strengthening system, treating a bearing raceway area, and forming depth d in the raceway area 1 The first plastic strengthening layer with the thickness of 1mm is prefabricated with high-amplitude residual compressive stress, the maximum residual compressive stress can reach more than 800MPa, and the microhardness of the first plastic strengthening layer is improvedCan reach more than 30 percent.
(5) And fixing the reinforced bearing on a micro-scale laser shock reinforcement system, tearing off the black adhesive tape used in the previous process, and avoiding adopting any absorption protection layer.
(6) On a microscale laser shock strengthening system, pulse laser parameter setting is carried out, the laser energy is 10mJ, the diameter of a light spot is 100 mu m, the pulse width is 5ns, the repetition frequency is 100Hz, and the laser power density is 25.48GW/cm 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(7) The bearing roller path is subjected to microscale laser shock strengthening treatment in a water-light same path mode, laser ablation can occur on the surface of the roller path, and the ablation layer is several micrometers, but can be at depth d 2 Form high degree grain refinement within 600 μm, even reach nanocrystalline structure level, and form high uniform plastic deformation, so that the distribution of mechanical properties such as residual compressive stress, hardness, etc. is more uniform, and the numerical fluctuation value is controlled within 10%.
(8) Finally, carrying out technological treatments such as fine grinding, polishing and the like on the bearing roller path, and removing the machining allowance d 0 The thickness d of the bearing roller path is 10mm, and the surface finish and the like also meet the related technical requirements.
(9) The combined strengthening process method forms a plastic strengthening/hardening layer with large depth through a large-energy, large-light-spot, long-pulse width and low-repetition-frequency process method; forming a plastic strengthening/hardening layer with high uniformity on a shallow surface layer by a small-energy, small-light-spot, short-pulse width and high-repetition frequency process method; and then the surface finish degree is ensured to meet the related technical requirements through working procedures such as fine grinding, polishing and the like, so that the rolling contact fatigue performance of the bearing is improved more remarkably.
Example 3: the main bearing of an aeroengine is taken as an example for carrying out a combined strengthening process, and the main bearing is made of M50 steel, the width of a roller path is 30mm, and the thickness of the roller path is 10mm. The specific implementation process is as follows:
(1) Cutting, turning and other mechanical processing on the bearing blank, coarse grinding in grinder to thickness of 10.2mm, stopping and reserving thickness d 0 A machining allowance of 0.2mmAnd measuring the layer.
(2) A black adhesive tape is used as an absorption protective layer and is adhered to the surface of a bearing roller path, then the bearing is fixed on a 5-axis robot arm, and deionized water flow is applied to the roller path area through a universal joint water pipe, so that a water curtain of 1-2 mm is formed on the surface of the roller path and is used as a constraint layer.
(3) The bearing roller way faces the fixed light path outlet by adjusting the gesture of the robot arm, then pulse laser parameter setting is carried out by a laser impact strengthening integrated control system, the laser energy is 10J, the spot diameter is 3mm, the pulse width is 20ns, the repetition frequency is 5Hz, and the laser power density is 7.08GW/cm 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(4) Starting a traditional laser shock strengthening system, treating a bearing raceway area, and forming depth d in the raceway area 1 The first plastic strengthening layer with the thickness of 1.2mm is prefabricated with high-amplitude residual compressive stress, the maximum residual compressive stress can reach more than 700MPa, and the microhardness can be improved by more than 20%.
(5) And fixing the reinforced bearing on a micro-scale laser shock reinforcement system, tearing off the black adhesive tape used in the previous process, and avoiding adopting any absorption protection layer.
(6) On a microscale laser shock strengthening system, pulse laser parameter setting is carried out, the laser energy is 50mJ, the diameter of a light spot is 300 mu m, the pulse width is 5ns, the repetition frequency is 500Hz, and the laser power density is 14.15GW/cm 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(7) The bearing roller path is subjected to microscale laser shock strengthening treatment in a water-light same path mode, laser ablation can occur on the surface of the roller path, and the ablation layer is several micrometers, but can be at depth d 2 The high-degree grain refinement is formed in 400 mu m, even the nanocrystalline structure level is reached, and the high-uniformity plastic deformation is formed, so that the distribution of mechanical properties such as residual compressive stress, hardness and the like is more uniform, and the numerical fluctuation value is controlled within 10%.
(8) Finally, carrying out process treatments such as fine grinding, polishing and the like on the bearing roller path,removing the machining allowance d 0 The thickness d of the bearing roller path is 10mm, and the surface finish and the like also meet the related technical requirements.
(9) The combined strengthening process method forms a plastic strengthening/hardening layer with large depth through a large-energy, large-light-spot, long-pulse width and low-repetition-frequency process method; forming a plastic strengthening/hardening layer with high uniformity on a shallow surface layer by a small-energy, small-light-spot, short-pulse width and high-repetition frequency process method; and then the surface finish degree is ensured to meet the related technical requirements through working procedures such as fine grinding, polishing and the like, so that the rolling contact fatigue performance of the bearing is improved more remarkably.
Comparative example 1: the main bearing of an aeroengine is reinforced by a traditional process, and the main bearing is made of M50 steel, the width of a roller path is 30mm, and the thickness of the roller path is 10mm. The specific implementation process is as follows:
(1) Cutting, turning and other mechanical processing on the bearing blank, coarse grinding in grinder to thickness of 10.2mm, stopping and reserving thickness d 0 A machining allowance layer of 0.2 mm.
(2) A black adhesive tape is used as an absorption protective layer and is adhered to the surface of a bearing roller path, then the bearing is fixed on a 5-axis robot arm, and deionized water flow is applied to the roller path area through a universal joint water pipe, so that a water curtain of 1-2 mm is formed on the surface of the roller path and is used as a constraint layer.
(3) The bearing roller way faces the fixed light path outlet by adjusting the gesture of the robot arm, then pulse laser parameter setting is carried out by a laser impact strengthening integrated control system, the laser energy is 10J, the spot diameter is 3mm, the pulse width is 20ns, the repetition frequency is 5Hz, and the laser power density is 7.08GW/cm 2 And designing a facula lap joint scheme and an implementation path for the whole rollaway nest, and making a process task.
(4) Starting a traditional laser shock strengthening system, treating a bearing raceway area, and forming depth d in the raceway area 1 The first plastic strengthening layer with the thickness of 1.2mm is prefabricated with high-amplitude residual compressive stress, the maximum residual compressive stress can reach more than 700MPa, and the microhardness can be improved by more than 20%.
(5) Finally, the bearingThe raceway is subjected to process treatments such as fine grinding, polishing and the like, and the machining allowance d is removed 0 The bearing raceway thickness dimension d was made 10mm.
Test comparison and results: comparative analysis of the reinforced bearings of comparative example 1 and example 3
1. The depth distribution of the residual compressive stress was tested and the results are shown in fig. 3. As can be seen from fig. 3, in the conventional process, the depth distribution of the residual compressive stress fluctuates greatly in the shallow surface layer region, whereas the depth distribution of the residual compressive stress is smoother and more uniform in the combined strengthening process of the present invention, regardless of whether it is the shallow surface layer region or the deep layer region.
2. The surface microstructure was examined and the results are shown in fig. 4. As can be seen from fig. 4, the uniformity of the strengthening layer in the conventional process is inferior to that in the combined strengthening process of the present invention.
3. The contact fatigue properties were measured, and the results are shown in FIG. 5. As can be seen from fig. 5, the average contact fatigue life of the combined strengthening process is approximately 2 times that of the conventional strengthening process.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. It is therefore intended that all equivalent modifications and changes made by those skilled in the art without departing from the spirit and technical spirit of the present invention shall be covered by the appended claims.
Claims (10)
1. A laser shock combined strengthening process for improving contact fatigue performance of a bearing is characterized by comprising the following steps of:
s1, preprocessing: reserving a machining allowance layer on the surface of a raceway of the bearing, wherein the thickness of the raceway is d, and the thickness of the machining allowance layer is d 0 ；
S2, sticking protection: attaching an absorption protective layer on the surface of a raceway of the bearing, and applying a constraint layer on the surface of the absorption protective layer;
s3, large-spot laser impact: laser shock enhancement roller with large light spotA track region formed to a depth d 1 D 1 ＞d 0 ；
S4, micro-scale laser shock: directly applying a constraint layer on the surface of the first plastic strengthening layer without absorbing a protective layer, and adopting microscale laser to impact and strengthen a raceway area to form a depth d 2 D 1 ＞d 2 ＞d 0 ；
S5, removing the reserved machining allowance layer.
2. The laser shock peening process for improving bearing contact fatigue performance according to claim 1, wherein: depth d of the first plastic reinforcing layer 1 The thickness of the roller path is 0.1 to 0.3 times of the thickness d.
3. The laser shock peening process for improving bearing contact fatigue performance according to claim 1, wherein: the energy of the large-facula laser impact is larger than that of the microscale laser impact; the diameter of the light spot impacted by the large-light-spot laser is larger than that of the light spot impacted by the microscale laser; the pulse width of the large-spot laser impact is larger than that of the microscale laser impact; the repetition frequency of the large-spot laser shock is smaller than that of the micro-scale laser shock.
4. The laser shock peening process for improving bearing contact fatigue performance according to claim 1, wherein: the energy of the large-spot laser impact is 2-25J, the spot diameter is 1-3 mm, the pulse width is 20-50 ns, and the repetition frequency is 1-20 Hz.
5. The laser shock peening process for improving bearing contact fatigue performance according to claim 4, wherein: the depth of the first plastic strengthening layer is 1-2 mm.
6. The laser shock peening process for improving bearing contact fatigue performance according to claim 1, wherein: the energy of the micro-scale laser impact is 10-500 mJ, the diameter of a light spot is 100-500 mu m, the pulse width is 5-10 ns, and the repetition frequency is 100-1000 Hz.
7. The laser shock peening process for improving bearing contact fatigue performance according to claim 6, wherein: the depth of the second plastic strengthening layer is 0.4-0.6 mm.
8. The laser shock peening process for improving bearing contact fatigue property according to any one of claims 1 to 7, wherein: the absorption protective layer adopts a black adhesive tape; the constraint layer is a water curtain formed by applying deionized water.
9. The laser shock peening process for improving bearing contact fatigue property according to claim 1 or 2 or 3, wherein: and (5) removing the reserved machining allowance layer in the step (S5) and adopting a fine grinding and polishing process to machine and remove the machining allowance layer on the surface of the roller path.
10. The bearing processing technology is characterized in that: a laser shock combining strengthening process for improving bearing contact fatigue performance according to any one of claims 1 to 9.
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| CN202311412893.6A CN117512323A (en) | 2023-10-27 | 2023-10-27 | Laser impact combined strengthening process for improving contact fatigue performance of bearing |
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| CN202311412893.6A CN117512323A (en) | 2023-10-27 | 2023-10-27 | Laser impact combined strengthening process for improving contact fatigue performance of bearing |
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