Shaft surface ultrasonic rolling-laser shock composite strengthening device and method

Abstract

The invention discloses a shaft surface ultrasonic rolling-laser shock composite strengthening device and method. The device comprises a laser shock system, an ultrasonic rolling system, a part clamping system and a machining working platform. The laser shock system can realize laser shock and automatic replacement of an absorption layer; the ultrasonic rolling system can realize ultrasonic rolling processing; and the part clamping system can realize the rotary motion and the axial motion of the shaft part. By means of the device, full-automatic machining of ultrasonic rolling and laser shock on the surface of the shaft is achieved. By means of the device and method, laser shock and ultrasonic rolling are distributed on the two sides of the shaft piece, the ultrasonic-laser-workpiece space position analysis relation is clarified, and synchronous machining of ultrasonic rolling and laser shock is achieved. In addition, the relation among laser-ultrasonic-workpiece machining parameters is established, and efficient and high-quality machining of ultrasonic rolling-laser shock on the surfaces of shafts such as aero-engine spindles, helicopter rotor shafts and gas turbine rotors is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface strengthening of metal materials, and particularly relates to an ultrasonic rolling-laser shock composite strengthening device for the surface of shaft parts, which is mainly used for strengthening the anti-fatigue, corrosion resistance and wear resistance of the surfaces of shaft parts such as aero-engine main shafts, helicopter rotor shafts, and gas turbine rotors. Background Art

[0002] Shaft parts are one of the core components of mechanical equipment, mainly used for supporting components, transmitting torque and bearing loads. However, under the influence of factors such as harsh service environments, inherent material defects, and excessive working loads, shaft parts such as aero-engine main shafts, helicopter rotor shafts, and gas turbine rotors are prone to failure forms such as distortion, fracture, wear, fatigue, and corrosion. This not only causes mechanical equipment to be unable to work properly, but may also pose hazards to economic property and life and health. Among them, surface integrity is the key factor affecting the failure of shaft parts.

[0003] The surface severe plastic deformation technology induces plastic deformation on the material surface to construct a gradient nanostructure, thereby inducing beneficial effects such as grain refinement strengthening, dislocation strengthening, precipitation strengthening, work hardening, and residual compressive stress, improving the wear resistance, corrosion resistance and fatigue resistance of the material, and extending the service life of shaft parts. Common surface severe plastic deformation technologies include laser shock and ultrasonic rolling. With the rapid development of high-end equipment manufacturing, a single surface severe plastic deformation technology has been difficult to meet the surface strengthening and service requirements of shaft parts. Therefore, combining laser shock and ultrasonic rolling is expected to further improve material properties.

[0004] At present, relevant patents have carried out relevant research: The Chinese invention patent with the publication number CN114438307A proposes a laser shock-ultrasonic rolling composite surface strengthening treatment method, which forms residual compressive stress with higher amplitude and deeper influence layer by sequentially performing laser shock and ultrasonic rolling on the workpiece, and at the same time significantly reduces the surface roughness and greatly improves the fatigue life of metal components. The Chinese invention patent with the publication number CN116590517A proposes a movable laser shock composite ultrasonic shock device and method, which realizes the synchronous operation of laser and ultrasonic shocks on the surface of workpieces with complex shapes.

[0005] However, the above-mentioned invention patents still have the following disadvantages: First, the spatial distribution of the two technologies of laser shock and ultrasonic rolling lacks a clear definition, resulting in difficulty in realizing synchronous processing, low automation degree, and low processing efficiency. Second, an effective connection between laser, ultrasonic and workpiece processing and motion parameters has not been established, making it difficult to achieve high-quality processing of the two technologies. Summary of the Invention

[0006] The object of the present invention is to provide a device for ultrasonic rolling-laser shock composite strengthening of the surface of a shaft part, so as to solve the above-mentioned technical problems existing in the prior art.

[0007] To achieve the above object, in one aspect, the present invention provides a device for ultrasonic rolling-laser shock composite strengthening of the surface of a shaft part, including a part clamping system, a laser shock system and an ultrasonic rolling system arranged on a processing workbench. The shaft part is clamped in the part clamping system, and the laser shock system and the ultrasonic rolling system are distributed on both sides of the shaft part to realize synchronous processing of ultrasonic rolling and laser shock.

[0008] The laser shock system includes a water spraying unit, an absorption layer replacement unit and a pulsed laser generator. The water spraying unit is used to form a flowing water curtain as a confinement layer; a pulsed laser is formed by the laser generator and irradiated on the absorption layer on the surface layer of the shaft part, and under the restriction of the confinement layer, a laser shock wave is formed to perform shock strengthening on the surface of the shaft part; the absorption layer replacement unit realizes automatic replacement of the absorption layer.

[0009] The ultrasonic rolling system includes a fixed base, a moving module, an ultrasonic generator and a roller. The ultrasonic generator is installed on the fixed base through the moving module, and the roller is rotatably connected to the processing end of the ultrasonic generator to apply the ultrasonic shock wave generated by the ultrasonic generator to the surface of the shaft part.

[0010] Optionally, in the laser shock system, the frequency of the pulsed laser is 1-10 Hz, the spot radius is 1-10 mm, the spot overlap rate is 50%, the pulse width is 5-100 ns, the laser wavelength is 1064 nm, and the laser energy is 2-20 J.

[0011] Optionally, in the ultrasonic rolling system, the ultrasonic frequency is 20-50 kHz, the ultrasonic amplitude is 1-20 μm, and the ultrasonic static pressure is 50-500 N.

[0012] Optionally, the length of the roller is 1-2 times the radius of the pulsed laser spot.

[0013] Optionally, the absorption layer replacement unit includes a unwind reel, a wind-up reel, a tensioning wheel, a reversing wheel and an absorption layer. The unwind reel and the wind-up reel are synchronously driven by motors to release a new absorption layer and recycle the old layer.

[0014] Optionally, the part clamping system includes a ground rail, a slide table sliding on the ground rail, a three-jaw chuck and a center installed on the slide table, and a motor for driving the rotation of the three-jaw chuck. The three-jaw chuck and the center are used to clamp the shaft part from both ends.

[0015] In another aspect, the present invention also provides a method for ultrasonic rolling-laser shock composite strengthening of the surface of a shaft part. According to the device for ultrasonic rolling-laser shock composite strengthening of the surface of a shaft part described in any one of the above, the method includes the following steps:

[0016] Step 1: Grind the surface of the shaft part to remove surface impurities and oxides;

[0017] Step 2: Clamp the shaft part in the part clamping system, and adjust the part clamping system so that the shaft part can perform rotational motion and axial movement synchronously;

[0018] Step 3: Apply an absorption layer on the surface of the shaft part, and form a flowing water curtain through the water spraying unit as a constraint layer;

[0019] Step 4: Start the laser shock system and the ultrasonic rolling system, so that the pulsed laser irradiates the absorption layer on one side of the shaft part to generate a laser shock wave, and at the same time apply an ultrasonic shock wave to the other side of the shaft part through the roller of the ultrasonic rolling system to realize the synchronous processing of laser shock and ultrasonic rolling;

[0020] Step 5: Through the linkage control of the rotation and axial movement of the part clamping system, the surface of the shaft part is subjected to composite strengthening processing area by area, and after each laser shock, the absorption layer is automatically replaced and the processing position is adjusted.

[0021] In some optional methods of the present invention, the replacement of the absorption layer in step 5 is realized by the synchronous drive of the unwinding wheel and the winding wheel, and its rotation speed satisfies the following relationship:

[0022]

[0023] where s is the rotation speed of the unwinding wheel and the winding wheel, in r / min; f laser is the laser frequency; r laser is the radius of the pulsed laser spot; R axis is the radius of the shaft part.

[0024] In some optional methods of the present invention, the rotation speed N of the shaft part in step 5 axis satisfies the relational expression:

[0025]

[0026] where n axis is the number of turns of the shaft part after a single laser shock, and the value is 5-100 r.

[0027] In some optional methods of the present invention, the axial movement of the shaft part is triggered once every X seconds, and the movement step length is the spot radius r laser ; where X satisfies the relational expression:

[0028]

[0029] The present invention discloses the following technical effects:

[0030] The present invention provides an ultrasonic rolling-laser shock composite strengthening device and method for the surface of a shaft part. Through structural innovation and parameter collaborative optimization, the surface strengthening effect is significantly improved. The main manifestations are as follows: By placing the laser shock system and the ultrasonic rolling system on both sides of the shaft part, synchronous processing is achieved; the laser shock wave (low frequency, high pressure) induces deep plastic deformation to form a gradient nanostructure and residual compressive stress; the ultrasonic shock wave (high frequency, low pressure) refines the surface grains and reduces the roughness. The combination of the two increases the microhardness by 54.9% and the residual compressive stress reaches -246.1 MPa, which is 10% - 47.6% higher than that of a single technology; the absorption layer replacement unit and the part clamping system are synergistically controlled to achieve automatic replacement of the absorption layer and full coverage of the processing area, ensuring processing continuity and increasing the efficiency by more than 30%; the device can process shaft parts of different sizes and materials, reduce the surface roughness to the micron level, and significantly extend the fatigue life, meeting the stringent requirements of high-end equipment for surface performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of the ultrasonic rolling-laser shock composite strengthening device for the surface of the shaft part of the present invention;

[0033] Figure 2 It is an axonometric view of the ultrasonic rolling-laser shock composite strengthening device for the surface of the shaft part of the present invention;

[0034] Figure 3 It is a schematic structural diagram of the laser shock system in the device of the present invention;

[0035] Figure 4 It is a schematic diagram of the ultrasonic rolling-laser shock composite strengthening principle for the surface of the shaft part of the present invention;

[0036] Figure 5 It is a processing flow chart of the ultrasonic rolling-laser shock composite strengthening for the surface of the shaft part of the present invention.

[0037] Among them, 1. machining workbench; 2. part clamping system; 21. ground rail; 22. sliding table; 23. three-jaw chuck; 24. shaft part; 25. center; 3. ultrasonic rolling system; 31. fixed base; 32. first moving module; 33. second moving module; 34. ultrasonic generator; 35. roller; 4. laser shock system; 41. pulsed laser; 42. water spraying unit; 421. water pump; 422. universal joint water spraying head; 43. absorber layer replacement unit; 431. unwind reel; 432. first reversing wheel; 433. second reversing wheel; 434. tensioning wheel; 435. absorber layer; 436. take-up reel; 437. constraint layer; 44. side plate; 5. ultrasonic shock wave; 6. laser shock wave. Detailed implementation manners

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0039] Through the background art, it can be understood that common surface deep plastic deformation technologies include laser shock and ultrasonic rolling. Laser shock: The absorber layer on the material surface is irradiated by pulsed laser, and under the restriction of the constraint layer, a laser shock wave is formed to induce ultra-high strain rate plastic deformation on the material surface. The laser shock wave has the characteristics of ultra-high pressure and short action time. Although the induced microhardness and residual compressive stress amplitude are small and the degree of grain refinement is low, the depth of the hardened layer and the residual compressive stress layer is large, and dislocation multiplication is significant. Ultrasonic rolling: The ultrasonic shock wave is induced by a roller / roller to act on the material surface, promoting high strain rate plastic deformation on the material surface. The ultrasonic shock wave has the characteristics of high pressure and long action time, and the induced microhardness and residual stress amplitude are high, and grain refinement is significant, but the hardened layer and the residual compressive stress layer are shallower.

[0040] However, with the rapid development of the high-end equipment manufacturing industry, a single surface deep plastic deformation technology has been difficult to meet the surface strengthening and service requirements of shaft parts. Therefore, there is an urgent need for a composite strengthening method and device that combines the advantages of laser shock and ultrasonic rolling to achieve synchronous processing of laser shock and ultrasonic shock. By introducing deep residual compressive stress through laser shock and combining ultrasonic rolling to refine the surface grains, a higher residual compressive stress amplitude and a deeper influence layer can be achieved. Utilizing the burnishing effect of ultrasonic rolling, the surface roughness can be significantly reduced, and the surface quality can be further improved. Through composite strengthening, the anti-fatigue, anti-wear and anti-corrosion properties of parts can be significantly improved. Finally, the purpose of improving the surface performance of shaft parts is achieved, and their service life and reliability under complex working conditions are improved to meet the requirements of high-end equipment manufacturing.

[0041] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0042] Embodiment 1:

[0043] Referring to Figures 1 to 3 As shown, the present invention provides a surface ultrasonic rolling-laser shock composite strengthening device for a shaft part, including a processing workbench 1, a part clamping system 2, a laser shock system 4, and an ultrasonic rolling system 3. The part clamping system 2, the laser shock system 4, and the ultrasonic rolling system 3 are all installed on the processing workbench 1 to cooperate to complete the strengthening treatment of the shaft part surface. The part clamping system 2 can clamp the shaft part 24 to be processed and realize the circumferential rotation and axial movement of the shaft part 24; the laser shock system 4 can realize the formation of the constraint layer 437, the automatic replacement of the absorption layer 435, and the laser shock strengthening treatment; the ultrasonic rolling system 3 can realize the ultrasonic rolling treatment.

[0044] Specifically, as Figure 2 shown, the part clamping system 2 is used to clamp the shaft part 24 and realize the circumferential rotation and axial movement of the shaft part 24. The part clamping system 2 mainly includes a ground rail 21, a sliding table 22, a three-jaw chuck 23, and a center 25. Among them, the sliding table 22 is slidably connected to the ground rail 21, and the three-jaw chuck 23 and the center 25 are both installed on the sliding table 22. The motor rotation drives the sliding table 22 to reciprocate along the ground rail 21, thereby realizing the axial movement of the shaft part 24. The shaft part 24 to be processed is clamped by the three-jaw chuck 23, and the circumferential rotation movement of the shaft part 24 is realized by relying on the motor to drive the three-jaw chuck 23 to rotate. The center 25 is used to support the shaft part 24 to maintain the necessary stiffness of the shaft part 24 during the strengthening process.

[0045] In a specific embodiment, the part clamping system 2 can clamp shaft parts 24 with different diameters and lengths, and the radius R of the shaft part 24 axis ranges from 10 to 100 mm, and the length L of the shaft part 24 ranges from 100 to 500 mm.

[0046] In a specific embodiment, the types of shaft parts 24 processed by the part clamping system 2 include smooth shafts, stepped shafts, and special-shaped shafts.

[0047] As Figure 3As shown in the figure, the laser shock system 4 mainly includes a laser generator, a water spraying unit 42, an absorber layer replacement unit 43, and a side plate 44. Among them, the water spraying unit 42 and the absorber layer replacement unit 43 are both installed on the side plate 44. The pulsed laser 41 formed by the laser generator irradiates on the absorber layer 435 on the surface of the shaft part 24. Under the restriction of the constraint layer 437, a laser shock wave 6 is formed to impact and strengthen the material surface. The absorber layer replacement unit 43 is composed of a unwind reel 431, a take-up reel 436, a tension pulley 434, a first reversing pulley 432, and a second reversing pulley 433. Through the linkage of the take-up reel 436 and the unwind reel 431, the automatic replacement of the constraint layer 437 in the laser shock area is realized, so as to realize the automatic processing of the shaft part surface. The water spraying unit 42 is composed of a water pump 421 and a universal joint bamboo joint water spraying head 422.

[0048] Using the above laser shock system 4 for laser shock requires a pulsed laser 41, an absorber layer 435, a constraint layer 437, etc. The absorber layer 435 is used to absorb laser energy to form a plasma and prevent the laser from ablating the surface of the shaft part 24. The constraint layer 437 is mainly used to increase the action pressure of the laser shock wave 6 and play a certain cooling role.

[0049] In a specific embodiment, the constraint layer 437 is formed by the water spraying unit 42, and the water curtain flowing out of the water gun is used as the constraint layer 437. In order to make the water flow down naturally and obtain a uniform constraint layer 437, the water gun is preferably placed above the pulsed laser 41 and close to the shaft part 24. Further, the thickness of the flowing water curtain is adjusted by adjusting the universal joint bamboo joint water spraying head 422, and the preferred thickness is a 2-mm flowing water curtain.

[0050] In a specific embodiment, the material of the absorber layer 435 is selected as a relatively thick aluminum foil or black tape. Specifically, the absorber layer 435 can be selected as a 0.15-mm thick black tape, and the adhesion pressure of the black tape is maintained at 100 N by adjusting the tension pulley 434, so that the black tape tightly adheres to the surface of the shaft part 24.

[0051] In a specific embodiment, the automatic replacement of the absorber layer 435 is realized through the linkage movement of the take-up reel 436 and the unwind reel 431. The positions of the take-up reel 436 and the unwind reel 431 need to be installed on the side close to the laser shock and should not hinder the ultrasonic rolling process.

[0052] As Figure 2As shown in the figure, the ultrasonic rolling system 3 includes a fixed base 31, a first moving module 32, a second moving module 33, an ultrasonic generator 34, and a roller 35. The first moving module 32 and the second moving module 33 are installed above the fixed base 31; the ultrasonic generator 34 is installed on the first moving module 32 and the second moving module 33. By adjusting the module and the fixed base 31, the processing end of the ultrasonic generator 34 is tangent to the surface of the shaft member 24 with different radii, and the center line of the ultrasonic generator is coaxial with the pulsed laser 41.

[0053] In the above embodiment, in the ultrasonic rolling system 3, the ultrasonic generator generates high-frequency electrical signals, driving the ultrasonic actuator (roller 35) connected thereto to generate high-frequency mechanical vibrations. These vibrations are transmitted to the surface of the shaft member 24 through the roller 35, forming ultrasonic shock waves 5 in the contact area. The ultrasonic shock waves 5 act on the surface of the shaft member 24, inducing high strain rate plastic deformation of the material, thereby achieving the surface strengthening and finishing effects.

[0054] In a specific embodiment, the roller 35, as the ultrasonic actuator, can act the ultrasonic shock waves 5 on the surface of the shaft member 24. In addition, the roller 35 can rotate itself, effectively reducing the friction between it and the shaft member 24, thereby avoiding scratching or adhesion phenomena on the surface of the shaft member 24. The processing end of the ultrasonic generator 34 is connected to the roller 35. In order to ensure that the single ultrasonic rolling processing area should be larger than the single laser shock area, the length B of the roller 35 ultrasonic is the spot radius is r laser is 1 to 2 times of, that is, B ultrasonic =(1 - 2)r laser , in unit of mm.

[0055] In a further optimized solution, the ultrasonic rolling action area needs to be larger than the laser shock action area.

[0056] In a further optimized solution, the center line of the ultrasonic actuator should be coaxial with the center line of the pulsed laser 41, and both the roller 35 and the front end of the pulsed laser 41 need to be tangent to the surface of the shaft member 24 to be processed, so that the ultrasonic rolling and laser shock processing areas effectively coincide at the same time, better realizing the ultrasonic rolling - laser shock composite strengthening.

[0057] The working principle of the embodiment of the present invention:

[0058] The pulsed laser 41 is loaded onto the surface of the shaft part. The absorption layer 435 attached to the surface of the shaft part 24 absorbs the energy of the pulsed laser 41 to induce plasma. Under the restriction of the constraint layer 437, a laser shock wave 6 with low frequency (in the order of Hz), ultra-high pressure (in the order of GPa), and short pulse width (in the order of ns) is formed and acts on the surface of the shaft part 24, causing plastic deformation of the surface material of the shaft part 24. At the same time, the ultrasonic actuator generates high-frequency and low-amplitude vibrations, and through the roller 35, an ultrasonic shock wave 5 with high frequency (in the order of kHz), low pressure (in the order of MPa), and long pulse width (in the order of μs) is loaded onto the surface of the shaft part 24, promoting further plastic deformation on the surface of the shaft part. Thanks to the combined effect of the ultrasonic shock wave 5 and the laser shock wave 6, the plastic deformation produces a superimposed effect, significantly improving the surface microstructure, mechanical properties, and surface topography of the shaft part, etc., and then realizing the integration of surface finishing and surface strengthening effects.

[0059] The combined strengthening effect of ultrasonic rolling-laser shock mainly reflects in the microstructure, surface topography, and mechanical properties. In terms of microstructure: First, the laser shock wave 6 induces a gradient structure mainly composed of high-density dislocations and complex dislocation structures in the material. On this basis, the high-frequency effect of the ultrasonic shock wave 5 reduces the dislocation threshold and induces a severe dynamic recrystallization effect, thereby forming ultra-nanocrystalline grains, and finally constructing a gradient nanostructure characterized by high-density dislocations and ultra-fine nanocrystalline grains. In terms of mechanical properties: The severe plastic deformation induced by the laser shock wave 6 and the ultrasonic shock wave 5 will produce a significant work-hardening effect and implant residual compressive stress, and finally form a hardened layer and a residual compressive stress layer with high amplitude and large influence depth. In terms of surface topography: The acoustic softening effect induced by the ultrasonic shock wave 5 promotes the plastic flow of the surface material of the shaft part, achieving the effect of "leveling the peaks and filling the valleys", reducing the surface roughness of the material to the micron level, and realizing the mirror finishing effect.

[0060] The embodiment of the present invention also provides a method for combined strengthening of ultrasonic rolling-laser shock on the surface of a shaft part. This method uses the above-mentioned device for combined strengthening of ultrasonic rolling-laser shock on the surface of a shaft part, and includes the following steps:

[0061] Step 1: Grind the surface of the shaft part 24 to remove surface impurities and oxides.

[0062] Step 2: Install and clamp the shaft part 24 on the three-jaw chuck 23, and use the center point 25 to align with the rear end face of the shaft part 24; wind the absorption layer 435 on the tape replacement unit, and adjust the tension wheel 434 to ensure that the absorption layer 435 tightly adheres to the surface of the shaft part 24; turn on the water pump 421, and adjust the universal joint water spray head 422 to flow out a flowing water curtain; according to the processing requirements, set the parameters of ultrasonic rolling and laser shock.

[0063] Step 3: Adjust the first moving module 32, the second moving module 33 and the fixed base 31 to make the roller 35 tangent to the shaft part 24; meanwhile, ensure that the ultrasonic rolling processing path covers the laser shock area; turn on the external laser to generate pulsed laser 41 and irradiate it on the surface of the shaft part 24; meanwhile, turn on the ultrasonic generator 34 and load the ultrasonic roller 35 onto the surface of the shaft part 24; then, start the ultrasonic rolling-laser shock composite strengthening processing.

[0064] Step 4: After the laser shocks once, the shaft part 24 rotates n axis circles, that is, the ultrasonic rolling is n axis circles; then, the unwinding wheel 431 and the winding wheel 436 move to replace the tape in the laser shock area and start the second laser shock; reciprocate in this way for processing. After processing one circle (i.e., after Xs), the sliding table 22 moves the spot radius r laser and moves to a new processing area; through the linkage and cooperation of the part clamping system 2, the laser shock system 4 and the ultrasonic rolling system 3, the ultrasonic rolling-laser composite strengthening processing of the surface of the shaft part 24 is completed (a total of Ts).

[0065] Step 5: After the processing is completed, remove the shaft part 24; after the CNC lathe cuts off the unprocessed part, store it in the processed area.

[0066] In a specific embodiment, the frequency f laser of the pulsed laser 41 is 1 - 10 Hz, preferably 5 Hz; the spot radius is r laser is 1 - 10 mm, preferably 3 mm; the spot overlap rate is 50%; the pulse width is 5 - 100 ns, preferably 15 ns; the laser wavelength is 1064 nm; the laser energy is 2 - 20 J, preferably 10 J.

[0067] In a specific embodiment, the absorption layer 435 applied to the laser shock area must be continuously updated to ensure the laser shock strengthening effect and prevent laser ablation of the surface of the shaft part 24. The replacement of the absorption layer 435 is realized by the synchronous drive of the unwinding wheel 431 and the winding wheel 436, and its rotation speed satisfies the following relationship:

[0068]

[0069] where s is the rotation speed (r / min) of the unwinding wheel 431 and the winding wheel 436, f laser is the laser frequency, r laser is the spot radius of the pulsed laser 41, and R axis is the radius of the shaft part 24.

[0070] In a specific embodiment, the ultrasonic frequency is 20 - 50 kHz, preferably 28 kHz; the ultrasonic amplitude is 1 - 20 μm, preferably 5 μm; the ultrasonic static pressure is 50 - 500 N, preferably 100 N.

[0071] To achieve efficient and high-quality machining of the surface of the shaft part 24, the characteristics of the surface strengthening parameters of the ultrasonic rolling-laser shock composite strengthening of the shaft part 24 lie in that there is a corresponding matching relationship among machining and motion parameters such as the shaft radius, shaft rotation speed, laser frequency, spot radius, and winding wheel rotation speed. The three-jaw chuck 23 rotates to realize the circumferential rotation motion of the shaft part 24, and the slide table 22 realizes the axial linear movement of the shaft part 24. Through the cooperation of the rotational motion and the axial movement, the entire surface of the shaft part 24 is machined. The circumferential motion rotation speed N of the shaft part 24 axis satisfies the relationship:

[0072] where n axis is the number of turns that the shaft part 24 rotates after a single laser shock, and its value ranges from 5 to 100 r.

[0073] In a specific embodiment, in order to reduce the formation of an array of pit morphologies on the surface of the shaft part 24 due to laser shock-induced plastic deformation and ensure that the surface of the shaft part 24 reaches a mirror finish after ultrasonic rolling, the number of turns n that the shaft part 24 rotates after a single laser shock axis needs to be 5 to 100 r.

[0074] The axial movement of the shaft part 24 triggers a movement once every X seconds, and the movement step size is the spot radius r laser . Where X satisfies the relationship:

[0075]

[0076] Furthermore, according to the above motion relationship, the total duration T required for machining the shaft part 24 satisfies the relationship:

[0077]

[0078] In a further optimized solution, the ultrasonic rolling-laser shock composite strengthening method for the shaft surface is applicable to materials such as titanium alloy, nickel-based alloy, aluminum alloy, magnesium alloy, and stainless steel.

[0079] In a further optimized solution, for high-strength alloys such as titanium alloy and nickel-based alloy, in order to improve the ultrasonic rolling machining effect, lubricants and coolants need to be added.

[0080] Example 2:

[0081] In a specific embodiment, referring to Figure 5 , taking the surface machining of a 2024-T351 aluminum alloy shaft part as an example, the length of the 2024-T351 aluminum alloy shaft part is 120 mm (the machining section is 100 mm), and the radius is 10 mm. The specific machining steps are as follows:

[0082] Step 1: Grind the surface of the shaft part 24 to remove surface impurities and oxides.

[0083] Step 2: Install and clamp the shaft part 24 on the three-jaw chuck 23, and align the rear end face of the shaft part 24 using the center drill 25. A black tape with a thickness of 0.15 mm is wound around the tape replacement unit, and the tension pulley 434 is adjusted to ensure that the black tape is tightly attached to the surface of the shaft part 24. Turn on the water pump 421 and adjust the universal joint sprinkler head 422 to flow out a flowing water curtain with a thickness of 2 mm. Set the laser energy to 10 J, the laser frequency to 5 Hz, and the spot radius to 3 mm. Set the length of the roller 35 to 5 mm, the ultrasonic frequency to 28 kHz, the ultrasonic amplitude to 5 μm, and the static pressure to 100 N.

[0084] Step 3: Adjust the first moving module 32, the second moving module 33, and the fixed base 31 so that the roller 35 is tangent to the shaft part 24. At the same time, ensure that the ultrasonic rolling processing path covers the laser shock area. Turn on the external laser to generate pulsed laser 41 and irradiate it on the surface of the shaft part 24. At the same time, turn on the ultrasonic generator 34 and load the ultrasonic roller 35 onto the surface of the shaft part 24. Subsequently, start the ultrasonic rolling-laser shock composite strengthening process.

[0085] Step 4: After the shaft part 24 rotates 10 circles after one laser shock, that is, the ultrasonic rolling is performed 10 circles. Subsequently, the unwinding wheel 431 and the winding wheel 436 move to replace the tape in the laser shock area and start the second laser shock. Repeat this reciprocating motion for processing. After the laser shock processing is completed for one circle (i.e., 9 s), the slide table 22 moves the spot radius rlaser to move to a new processing area. Through the linkage and cooperation of the part clamping system 2, the laser shock system 4, and the ultrasonic rolling system 3, the ultrasonic rolling-laser composite strengthening processing of the surface of the shaft part 24 is completed (a total of 297 s).

[0086] Step 5: After the processing is completed, remove the shaft part 24. The CNC lathe cuts off the unprocessed part and stores it in the processed area.

[0087] Through the above processing method, the surface properties of the 2024-T351 aluminum alloy shaft parts are significantly improved, as follows: The surface microhardness of the untreated specimen is 126.8 HV. The microhardness of the laser shock specimen is 172.2 HV, and the microhardness of the ultrasonic rolling specimen is 180.5 HV. The microhardness of the ultrasonic rolling-laser shock specimen is 196.4 HV, which is increased by 54.9%, 14.1% and 8.8% compared with the untreated, laser shock and ultrasonic rolling specimens respectively. The surface residual compressive stress of the untreated specimen is -20.2 MPa, the surface residual compressive stress of the laser shock specimen is -166.7 MPa, and the surface residual compressive stress of the ultrasonic rolling specimen is -223.6 MPa. The surface residual compressive stress of the ultrasonic rolling-laser shock specimen is -246.1 MPa, which is increased by 47.6% and 10.1% compared with the laser shock and ultrasonic rolling specimens respectively. The surface microhardness and residual compressive stress of the 2024-T351 aluminum alloy specimen treated by ultrasonic rolling-laser shock composite strengthening are much higher than those of single treatment.

[0088] Example 3:

[0089] In a specific embodiment, referring to Figure 5 , taking the surface machining of the Inconel 718 nickel-based superalloy aeroengine main shaft as an example, the length of the Inconel 718 nickel-based superalloy aeroengine main shaft is 2000 mm and the radius is 100 mm. The processing steps of the Inconel 718 nickel-based superalloy aeroengine main shaft are the same as those in Example 2 and will not be elaborated here.

[0090] Using the processing method of the present invention to process the Inconel 718 nickel-based superalloy aeroengine main shaft significantly improves the surface properties of the Inconel 718 nickel-based superalloy aeroengine main shaft, as follows: The surface microhardness of the untreated specimen is 274.2 HV (Vickers hardness). The microhardness of the laser shock specimen is 340.6 HV, and the microhardness of the ultrasonic rolling specimen is 342.5 HV. The microhardness of the ultrasonic rolling-laser shock specimen is 387.8 HV, which is increased by 41.4%, 13.9% and 13.2% compared with the untreated specimen, the single laser shock specimen and the single ultrasonic rolling specimen respectively. The surface residual compressive stress of the untreated specimen is -26.2 MPa, the surface residual compressive stress of the laser shock specimen is -268.4 MPa, and the surface residual compressive stress of the ultrasonic rolling specimen is -302.5 MPa. The surface residual compressive stress of the ultrasonic rolling-laser shock specimen is -368.5 MPa, which is increased by 37.2% and 21.8% compared with the laser shock and ultrasonic rolling specimens respectively. The surface microhardness and residual compressive stress of the Inconel 718 nickel-based superalloy specimen treated by ultrasonic rolling-laser shock composite strengthening are much higher than those of single treatment.

[0091] Compared with the prior art, the present embodiment discloses at least the following beneficial effects:

[0092] For the surface ultrasonic rolling-laser shock composite strengthening technology of the shaft part described in the present invention, by distributing laser shock and ultrasonic rolling on both sides of the shaft part 24, the spatial position relationship required for laser shock (pulse laser 41 beams, constraint layer 437, absorption layer 435) and ultrasonic rolling technology is clarified, realizing the synchronous processing of the two technologies. Utilizing the composite effect of laser shock wave 6 and ultrasonic shock wave 5, the surface performance of the shaft part 24 is improved, thereby increasing the service life of the shaft part 24.

[0093] Relying on the part clamping system 2, laser shock system 4 and ultrasonic rolling system 3, the present invention highly automatically realizes the composite shock on the surface of the shaft part, effectively improving the processing efficiency.

[0094] The present invention establishes the relationship between processing and motion parameters such as the radius of the shaft part, the rotational speed of the shaft part, the laser frequency, the spot radius, and the rotational speed of the rewinding wheel, matches the processing parameters of the two technologies, and thus realizes high-quality processing of the surface of the shaft part.

[0095] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention.

[0096] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A shaft surface ultrasonic rolling-laser shock composite strengthening device, characterized in that: The invention comprises a part clamping system (2), a laser impact system (4) and an ultrasonic rolling system (3) arranged on a processing workbench (1); a shaft (24) is clamped in the part clamping system (2); the laser impact system (4) and the ultrasonic rolling system (3) are distributed on both sides of the shaft (24), so as to realize synchronous processing of ultrasonic rolling and laser impact; The laser impact system (4) comprises a water spray unit (42), an absorption layer replacement unit (43) and a pulse laser (41) generator. The water spray unit (42) is used to form a flowing water curtain as a constraint layer (437). The pulse laser (41) is formed by the laser generator and irradiated on the absorption layer (435) on the surface of the shaft (24). Under the restriction of the constraint layer (437), a laser shock wave (6) is formed to impact strengthen the surface of the shaft (24). The absorption layer replacement unit (43) realizes automatic replacement of the absorption layer (435). The ultrasonic rolling system (3) comprises a fixed base (31), a movable module, an ultrasonic generator (34) and a roller (35); the ultrasonic generator is mounted on the fixed base (31) via the movable module; the roller (35) is rotatably connected to the processing end of the ultrasonic generator, so that the ultrasonic shock wave (5) generated by the ultrasonic generator (34) acts on the surface of the shaft (24).

2. The shaft surface ultrasonic rolling-laser shock composite strengthening device according to claim 1 is characterized in that: In the laser impact system (4), the frequency of the pulsed laser (41) is 1 to 10 Hz, the spot radius is 1 to 10 mm, the spot overlap rate is 50%, the pulse width is 5 to 100 ns, the laser wavelength is 1064 nm, and the laser energy is 2 to 20 J.

3. The shaft surface ultrasonic rolling-laser shock composite strengthening device according to claim 1 is characterized in that: In the ultrasonic rolling system (3), the ultrasonic frequency is 20 to 50 kHz, the ultrasonic amplitude is 1 to 20 μm, and the ultrasonic static pressure is 50 to 500N.

4. The shaft surface ultrasonic rolling-laser shock composite strengthening device according to claim 1 is characterized in that: The length of the roller (35) is 1 to 2 times the radius of the pulse laser spot (41).

5. The shaft surface ultrasonic rolling-laser shock composite strengthening device according to claim 1 is characterized in that: The absorption layer replacement unit (43) comprises an unwinding wheel (431), a rewinding wheel (436), a tensioning wheel (434), a reversing wheel and an absorption layer (435); the unwinding wheel (431) and the rewinding wheel (436) are synchronously driven to rotate by a motor to release a new absorption layer (435) and recycle an old layer.

6. The shaft surface ultrasonic rolling-laser shock composite strengthening device according to claim 1 is characterized in that: The part clamping system (2) comprises a ground rail (21), a slide table (22) sliding on the ground rail (21), a three-jaw chuck (23) and a center (25) mounted on the slide table (22), and a motor driving the three-jaw chuck (23) to rotate, wherein the three-jaw chuck (23) and the center (25) are used to clamp a shaft (24) from both ends.

7. A method for ultrasonic rolling-laser shock composite strengthening of shaft surface, according to the device for ultrasonic rolling-laser shock composite strengthening of shaft surface according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Grinding the surface of the shaft (24) to remove surface impurities and oxides; Step 2: Clamp the shaft (24) in the part clamping system (2), and adjust the part clamping system (2) so that the shaft (24) can perform rotational motion and axial movement synchronously; Step 3: applying an absorption layer (435) on the surface of the shaft (24), and forming a flowing water curtain as a constraint layer (437) through a water spray unit (42); Step 4: Start the laser shock system (4) and the ultrasonic rolling system (3), so that the pulsed laser (41) irradiates the absorption layer (435) on one side of the shaft (24) to generate a laser shock wave (6), and at the same time, the ultrasonic shock wave (5) is applied to the other side of the shaft (24) through the roller (35) of the ultrasonic rolling system (3), so as to achieve synchronous processing of laser shock and ultrasonic rolling; Step 5: The rotation and axial movement of the part clamping system (2) are controlled by linkage, so that the surface of the shaft (24) is subjected to composite strengthening processing region by region, wherein after each laser shock, the absorption layer (435) is automatically replaced and the processing position is adjusted.

8. The shaft surface ultrasonic rolling-laser shock composite strengthening method according to claim 7, characterized in that: The replacement of the absorption layer (435) in step 5 is achieved by synchronously driving the unwinding wheel (431) and the rewinding wheel (436), and the rotation speeds thereof satisfy the following relationship: Wherein, s is the rotation speed of the unwinding wheel (431) and the reeling wheel (436), in units of r / min; f laser is the laser frequency; r laser is the spot radius of the pulsed laser (41); R axis is the radius of the shaft member (24).

9. The method for ultrasonic rolling-laser shock composite strengthening of shaft surface according to claim 8, characterized in that: The rotation speed N of the shaft (24) in step 5 is axis Satisfies the relationship: Among them, n axis It is the number of revolutions of the shaft member (24) after a single laser impact, and the value is 5 to 100 r.

10. The shaft surface ultrasonic rolling-laser shock composite strengthening method according to claim 9, characterized in that: The axial movement of the shaft (24) triggers a movement after X seconds, and the movement step length is the spot radius r laser ; Among them, X satisfies the relationship:

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