Device and method for laser shock strengthening inside cylinder wall

Abstract

The present invention discloses a device and method for laser shock strengthening inside a cylinder wall, comprising a laser, a half-wave plate, a polarizing plate, an incident lens, a first displacement platform, a reflector, a water jet, an absorption layer spin coater, and a clamping platform; by extending the clamping platform equipped with the reflector, the water jet, and the absorption layer spin coater into the inside of the processing sample, focusing the incident laser focus on the inner wall of the processing sample through optical path adjustment, combining the absorption layer spin coater to spin coat the absorption layer on the inner wall surface and the water jet to perform water jet on the laser focus, so as to achieve the conditions for laser shock strengthening of the inner wall, and finally by multi-dimensional coordination and adjustment of two electric displacement platforms, laser shock strengthening processing of various positions of the inner wall of the processing sample is achieved, and finally the absorption layer is removed to complete the processing of laser shock strengthening of the inner wall. The present invention not only fills the gap in the field of laser shock strengthening inner wall processing, but also provides a technical solution for improving the service life of various types of cylinder components.

Description

Technical Field

[0001] The invention belongs to the technical field of laser shock strengthening processing, and specifically relates to a device and method for laser shock strengthening inside a cylinder wall. Background Art

[0002] Cylinder structures such as oil pipelines, internal combustion engine cavities, and the inner wall of artillery are often in harsh operating environments such as high temperature, high pressure, and high corrosion for a long time, which easily breeds cracks, broken edges and other defects in their inner walls. In the long run, it is easy to cause complete damage to the components and cause huge losses. The existing strengthening processing of the inner wall of the cylinder structure mostly adopts the traditional mechanical shot peening strengthening method. However, since the inner wall structure of the cylinder structure is a curved surface, it is difficult for the marbles to be evenly sprayed at various positions inside the cylinder wall, so the residual compressive stress layer generated is often not uniform. At the same time, due to the processing characteristics of mechanical shot peening, the residual stress layer obtained by shot peening is very shallow, only tens of microns thick, which has no obvious strengthening effect on the inner wall of the cylinder. More importantly, for cylinder structures with smaller calibers or larger calibers and long sizes, it is more difficult to achieve the conditions for shot peening to strengthen the inner wall of the cylinder. Mechanical shot peening is limited by the controllability of its equipment, and it is difficult to achieve the strengthening processing of the inner wall of cylinder structures of various calibers.

[0003] Laser shock peening, as an emerging material strengthening processing method, has received widespread attention in the aerospace field. Its principle is to use the absorption layer adsorbed on the surface of the component to absorb a large amount of laser energy, generate high-temperature and high-pressure plasma, and generate shock waves to the inside of the component substrate under the regulation of the confinement layer, thereby forming a hard layer of about 1 mm thick on the surface of the component and introducing a large amount of residual compressive stress, thereby improving the fatigue resistance and service life of the component. However, the design of internal laser shock peening of the cylinder wall structure is relatively complicated and has not been studied yet. Therefore, it is of great significance to study a laser shock peening technology for the inside of the cylinder wall to reduce the risk of damage to the cylinder wall during use and to increase the practical life of the cylinder wall. Summary of the invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and to provide a device and method for laser shock strengthening of the inside of a cylinder wall. The reflector, water jet injector and absorption layer spin coater are designed in an integrated manner, and the incident laser, absorption layer and constraint layer are integrated and fixed on a clamping platform, extending into the inside of the cylinder wall. Combined with the coordinated control of mechanical and optical parts, it is ensured that the focus of the laser inside the cylinder wall is always focused on the inner wall surface. Under the joint action of the absorption layer and the water flow as the constraint layer, the laser shock strengthening processing of the inside of the cylinder wall is realized. At the same time, by using a multi-dimensional displacement platform, all-round laser shock strengthening processing of the inside of a cylinder wall of any caliber and any length can be realized, and a strengthening layer with high residual compressive stress and thick hard layer is formed on its surface, thereby obtaining a better processing effect and increasing the service life of the inner wall of the cylinder.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0006] A device for laser shock strengthening inside a cylinder wall, comprising a laser, a half-wave plate, a polarizing plate, an incident lens, a first displacement platform, a reflecting mirror, a water jet, an absorption layer spin coater, and a clamping platform;

[0007] The reflector, water jet and absorption layer spin coater are clamped on the same clamping platform and connected to the second displacement platform through an adapter; the clamping platform is arranged inside the processing sample; the laser, half-wave plate, polarizing plate, incident lens, first displacement platform, reflector, water jet and absorption layer spin coater are arranged on the same optical axis in sequence; the incident lens is mounted on the first displacement platform; the water jet is connected to a water pump;

[0008] During laser shock peening, the second displacement platform translates or rotates along the optical axis, driving the reflector, water jet and absorption layer spin coater on the clamping platform to move synchronously. At the same time, the laser emits a laser, which is incident on the incident lens after passing through the half-wave plate and the polarizer, and then focused on the inner wall of the processed sample after passing through the reflector. The water jet sprays water to the focus position, and the absorption layer spin coater spins the absorption layer on the inner wall of the processed sample.

[0009] To optimize the above technical solutions, the specific measures taken also include:

[0010] The laser wavelength range of the above laser is 300nm-2000nm, and the laser energy adjustment range is 10μJ~100J.

[0011] The first displacement platform is used to adjust the position of the incident lens so that the incident lens is longitudinally translated along the optical axis to ensure that the focus is always focused on the surface of the inner wall of the processed sample.

[0012] The telescopic range of the first displacement platform is 0-30m, and the accuracy range is 0.01-0.05mm.

[0013] The absorption layer is made of black glue or black paint.

[0014] When the above-mentioned second displacement platform translates back and forth along the optical axis direction, the longitudinal depth position of the reflector, water jet and absorption layer spin coater on the clamping platform can be adjusted on the inner wall of the processed sample; when it rotates along the optical axis direction, the lateral position of the reflector, water jet and absorption layer spin coater on the clamping platform can be adjusted on the inner wall of the processed sample.

[0015] The telescopic range of the above-mentioned second displacement platform is 0-30m, the accuracy range is 0.01-0.05mm, the rotation range is 0-360 degrees, and the accuracy is 0.1-0.3μrad.

[0016] A method for laser shock strengthening inside a cylinder wall, specifically comprising the following steps:

[0017] S1, the laser beam emitted by the laser passes through the half-wave plate and the polarizer in sequence along the laser optical path, and then passes through the focusing lens mounted on the first displacement platform and the reflector mounted on the clamping platform, and is focused and irradiated to the inner wall surface of the processed sample. By adjusting the position of the first displacement platform, it is ensured that the laser focus always falls on the inner wall of the processed sample;

[0018] S2, adjusting the half-wave plate to adjust the incident laser to an incident laser energy density W within a set range, the absorption layer spin coater spins the absorption layer on the inner wall of the processed sample, and the water jet sprays water at the laser focus as a constraint layer to achieve the conditions for laser shock peening of the inner wall of the sample, and then moving the second displacement platform to perform laser shock peening on the longitudinal area depth of the processed sample;

[0019] S3, after completing the laser shock peening of the depth of the longitudinal region at the current position, turn off the laser, the water jet and the absorption layer spin coater, move the laser focus back to the entrance of the processed sample by moving the second displacement platform, rotate the second displacement platform, move the laser focus to other lateral positions of the inner wall of the processed sample, and adjust the position of the focusing lens by moving the first displacement platform to ensure that the laser focus remains focused on the inner wall surface of the processed sample, and then turn on the laser, the water jet and the absorption layer spin coater to carry out laser shock peening processing in the longitudinal depth region at the new lateral position of the inner wall of the processed sample;

[0020] S4, after repeating step S3 to complete the laser shock peening of all areas of the inner wall of the processed sample, the absorption layer spin-coated on the inner wall of the processed sample is removed, thereby completing the laser shock peening of the inner wall of the processed sample.

[0021] The incident laser energy density W within the setting range described in S2 above is obtained as follows:

[0022] According to formula (1) and formula (2), the surface residual compressive stress generated by laser shock wave is Plastic influence depth Fitting and screening to obtain the laser shock wave peak pressure P range corresponding to 1-2.5 times HEL;

[0023] Substitute the laser shock wave peak pressure P range corresponding to 1-2.5 times HEL into formula (3) to obtain the set incident laser density W range, so as to adjust the incident laser to the incident laser energy density W within the set range; ; (1)

[0024] ; (2)

[0025] ; (3)

[0026] In the formula, is the Lamé constant, is the shear modulus, is the spot radius, is Poisson's ratio, and is the propagation speed of elastic waves and plastic waves in the material, is the pressure pulse width, a is the conversion coefficient of internal energy into thermal energy, and Z is the acoustic impedance.

[0027] The present invention has the following beneficial effects:

[0028] The present invention extends a fixed frame equipped with a reflector, a water jet and an absorption layer spin coater into the interior of the processed sample, focuses the incident laser focus to the inner wall of the processed sample by adjusting the optical path, and combines the absorption layer spin coater to spin coat the absorption layer on the inner wall surface and the water jet to perform water jet at the laser focus as an absorption layer, thereby achieving the conditions for laser shock strengthening of the inner wall, and finally, through multi-dimensional coordination and adjustment of two electric displacement platforms, laser shock strengthening processing is achieved at various positions of the inner wall of the processed sample, and finally, the absorption layer is removed to complete the laser shock strengthening processing of the inner wall. The present invention not only fills the gap in the field of laser shock strengthening inner wall processing, but also provides a technical solution for improving the service life of various types of cylindrical components.

[0029] The present invention uses laser shock strengthening to prepare a strengthening layer with a thickness of more than 1 mm inside the cylinder wall, which not only improves the hardness, but also forms a high residual compressive stress inside. Compared with the traditional mechanical shot peening and impact strengthening, not only the depth of the residual compressive stress layer is deeper, the residual compressive stress is more significantly improved, and the laser shock strengthening process has better controllability, avoiding the randomness and unevenness of the inner wall of the cylinder in the mechanical shot peening and impact strengthening, and the operation is convenient and simple, and it is not easy to have operation problems such as projectile jamming, and it is more reliable;

[0030] The present invention can realize laser shock strengthening for the inside of the cylinder wall with different calibers through the coordinated processing of mechanical parts and optical parts, solving the problems that the projectiles of small-caliber components are difficult to match and easy to get stuck in the traditional mechanical shot peening and shock strengthening, and large-scale mechanical equipment is required to adjust the position of components for large-caliber components. The laser shock strengthening device for the inside of the cylinder wall of the present invention can realize laser shock strengthening processing for cylinder wall structures of different sizes by adjusting the size of optical components and mechanical parts and the motion range of the position of the displacement platform, without adjusting the posture of the components, and convenient processing;

[0031] The present invention can be used to perform laser shock strengthening processing on the inside of a cylinder wall of any metal or alloy element, and has high applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of laser shock strengthening inside a cylinder wall according to the present invention;

[0033] Figure 2 It is a structural schematic diagram of a laser shock strengthening device for the interior of a cylinder wall according to the present invention;

[0034] The meanings of the numbers in the figure are:

[0035] 1 - first laser, 2 - half-wave plate, 3 - polarizer, 4 - focusing lens, 5 - first displacement platform, 6 - reflector, 7 - water jet, 8 - absorption layer spin coater, 9 - clamping platform, 10 - absorption layer, 11 - processing sample, 12 - water pump, 13 - second displacement platform, 14 - adapter, 15 - computer. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] Although the steps in the present invention are arranged with numbers, they are not used to limit the order of the steps. Unless the order of the steps is clearly stated or the execution of a certain step requires other steps as a basis, the relative order of the steps can be adjusted. It is understood that the term "and / or" used in this article involves and covers any and all possible combinations of one or more of the associated listed items.

[0038] The device for laser shock strengthening inside a cylinder wall of the present invention comprises a laser 1, a half-wave plate 2, a polarizing plate 3, an incident lens 4, a first displacement platform 5, a reflector 6, a water jet 7, an absorption layer spin coater 8, and a clamping platform 9; wherein the reflector 6, the water jet 7, and the absorption layer spin coater 8 are clamped on the same clamping platform 9 and connected to a second displacement platform 13 through an adapter 14; the second displacement platform 13 can be translated along the optical axis direction and can also be rotated; the clamping platform 9 is arranged inside a processing sample 11; the laser 1, the half-wave plate 2, the polarizing plate 3, the incident lens 4, the first displacement platform 5, ... The incident mirror 6, the water jet 7, and the absorption layer spin coater 8 are arranged in sequence on the same optical axis; the incident lens 4 is mounted on the first displacement platform 5; the water jet 7 is connected to the water pump 12; the laser 1 used for laser shock strengthening emits a laser, which passes through the half-wave plate 2 and the polarizer 3, and is incident on the incident lens 4 mounted on the first displacement platform 5, and then passes through the reflector 6 and is focused on the inner wall of the processed sample 11; the water jet 7 is connected to the water pump 12 through a water pipe to ensure that the water jetted by the water jet 7 covers the focal position; the absorption layer spin coater 8 can spin coat the absorption layer 10 on the inner wall of the processed sample 11. During laser shock strengthening, the second displacement platform 13 translates or rotates along the optical axis, driving the reflector 6, water jet 7, and absorption layer spin coater 8 on the clamping platform 9 to move synchronously. At the same time, the laser 1 emits a laser, which passes through the half-wave plate 2 and the polarizer 3 and is incident on the incident lens 4, and then passes through the reflector 6 and is focused on the inner wall of the processed sample 11. The water jet 7 sprays water to the focus position, and the absorption layer spin coater 8 spins the absorption layer 10 on the inner wall of the processed sample 11.

[0039] Specifically, the second displacement platform 13 is used to adjust the overall position of the clamping platform 9, and then adjust the position of the laser shock peening. It can move forward and backward along the optical axis direction to adjust the longitudinal depth position of the inner wall of the processed sample 11, and can also be rotated to adjust the lateral position of the inner wall of the processed sample 11.

[0040] Specifically, the first displacement platform 5 is used to adjust the position of the lens, so as to realize the longitudinal movement of the lens along the optical axis, and ensure that the laser focus is always focused on the surface of the inner wall of the processed sample 11;

[0041] Specifically, the telescopic range of the first displacement platform 5 is 0-30m, and the accuracy range is 0.01-0.05mm;

[0042] Specifically, the telescopic range of the second displacement platform 13 is 0-30m, the accuracy range is 0.01-0.05mm, the rotation range is 0-360 degrees, and the accuracy is 0.1-0.3μrad;

[0043] Specifically, the laser wavelength range of the laser 1 is 300nm-2000nm, and the laser energy adjustment range is 10μJ~100J;

[0044] Specifically, the absorption layer 10 can be made of materials that can efficiently absorb laser energy, such as black glue and black paint.

[0045] A method for laser shock strengthening of the inner wall of a cylinder wall of the present invention is to perform laser shock strengthening processing on the inner wall of a processing sample, and the method specifically comprises the following steps:

[0046] S1, the laser beam emitted by the laser 1 passes through the half-wave plate 2 and the polarizing plate 3 along the laser optical path to adjust the incident laser energy, and then passes through the focusing lens 4 mounted on the first displacement platform 5 and the reflecting mirror 6 mounted on the clamping platform 9, and irradiates to the inner wall surface of the processed sample 11. By adjusting the position of the first displacement platform 5, it is ensured that the laser focus always falls on the inner wall of the processed sample 11;

[0047] S2, turn on the laser 1, and adjust the half-wave plate 2 so that the incident laser is adjusted to a suitable incident laser energy density W. At the same time, the absorption layer spin coater 8 starts to spin coat the absorption layer 10 on the inner wall of the processed sample, and the water jet 7 starts to spray water at the laser focus as a constraint layer, thereby achieving the conditions for laser shock intensive processing of the inner wall of the sample, and then move the second displacement platform 13 to perform laser shock intensive processing on the longitudinal area depth of the processed sample 11;

[0048] The adjustment of the incident laser energy density W is as follows:

[0049] Distribution of surface residual compressive stress and plastic influence depth generated by laser shock wave Model:

[0050] ; (1)

[0051] ; (2)

[0052] In the formula, is the surface residual stress, P is the peak pressure of the laser shock wave, is the Lamé constant, is the shear modulus, is the spot radius, is Poisson's ratio, and is the propagation speed of elastic waves and plastic waves in the material, is the pressure pulse width, and HEL is the maximum elastic stress of the material.

[0053] Combined with the relationship between laser incident energy density (W) and shock wave peak pressure (P):

[0054] ; (3)

[0055] In the formula, a is the conversion coefficient of internal energy to thermal energy, which is 0.1.

[0056] Z is the acoustic impedance, which is determined by the material properties;

[0057] The incident laser density (W) can be selected to optimally induce a shock wave peak pressure (P) of 1-2.5 times the maximum elastic stress (HEL) of the material.

[0058] S3, after completing the laser shock peening of the longitudinal depth of the position, turn off the laser 1, the water jet 7 and the absorption layer spin coater 8, move the laser focus back to the entrance of the processing sample 11 by moving the second displacement platform 13, and rotate the second displacement platform 13 to move the laser focus to other lateral positions of the inner wall of the processing sample 11, and at the same time adjust the position of the focusing lens 4 by moving the first displacement platform 5 to ensure that the laser focus is still focused on the inner wall surface of the processing sample 11, and continue to turn on the laser 1, the water jet 7 and the absorption layer spin coater 8 to carry out laser shock peening processing in the longitudinal depth area on the new lateral position of the inner wall of the processing sample 11;

[0059] S4, after laser shock peening is completed on all areas of the inner wall of the processed sample 11 according to step S3, the absorption layer 10 spin-coated on the inner wall of the processed sample is removed by wiping, removing, etc., thereby completing the laser shock peening processing of the inner wall of the processed sample 11.

[0060] The specific embodiments of the present invention are described in detail below by taking examples.

[0061] Assume that the inner wall depth of the sample 11 to be processed is 1m, the diameter is 0.2m of the aluminum alloy cylinder, the laser wavelength emitted by the laser 1 is 1064nm, the pulse width is 20ns, the repetition frequency is 10Hz, the single pulse laser energy is 10J, the diameter of the laser beam is 6mm, the focal length of the lens 4 is 2m, the moving range of the first displacement platform 5 is 5m, the accuracy is 0.05mm, and the displacement speed is 10mm / s. The moving range of the second displacement platform 13 is 5m, the accuracy is 0.05mm, the displacement speed is 10mm / s, and the absorption layer 10 is black glue.

[0062] First, the laser beam emitted by the laser 1 passes through the half-wave plate 2 and the polarizing plate 3 along the laser optical path to adjust the incident laser energy to 2J, and then passes through the focusing lens 4 mounted on the first displacement platform 5 and the reflector 6 mounted on the clamping platform 9, and irradiates to the inner wall surface of the aluminum alloy cylinder. By adjusting the position of the first displacement platform 5 to a focal distance of 2m, it is ensured that the laser focus always falls on the inner wall of the aluminum alloy cylinder;

[0063] Then, the laser 1 is turned on, and the half-wave plate 2 is adjusted so that the incident laser is adjusted to a suitable incident laser energy of 2J. At the same time, the absorption layer spin coater 8 starts to spin-coat black glue on the inner wall of the aluminum alloy tube, and the water jet 7 starts to spray water at the laser focus as a constraint layer, thereby achieving the conditions for laser shock strengthening the inner wall of the aluminum alloy tube. Subsequently, the second displacement platform 13 is moved to perform laser shock strengthening processing on the longitudinal area depth of the aluminum alloy tube.

[0064] Subsequently, after the laser shock peening of the longitudinal depth of the position is completed, the laser 1, the water jet 7 and the absorption layer spin coater 8 are turned off, and the laser focus is moved back to the entrance of the aluminum alloy cylinder by moving the second displacement platform 13, and the second displacement platform 13 is rotated to move the laser focus to other lateral positions of the inner wall of the aluminum alloy cylinder, and at the same time, the position of the focusing lens 4 is adjusted by moving the first displacement platform 5, so that the distance between the lens 4 and the light transmission to the inner wall of the aluminum alloy cylinder is still adjusted to 2m, ensuring that the laser focus is still focused on the inner wall surface of the aluminum alloy cylinder, and the laser 1, the water jet 7 and the absorption layer spin coater 8 are continued to be turned on to carry out laser shock peening processing in the longitudinal depth area on the new lateral position of the inner wall of the aluminum alloy cylinder;

[0065] Finally, according to the previous step, after laser shock strengthening of all areas of the inner wall of the aluminum alloy cylinder is completed, the black glue spin-coated on the inner wall of the processed sample is removed by wiping and removing, thereby completing the laser shock strengthening processing of the inner wall of the aluminum alloy cylinder.

[0066] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0067] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for laser shock peening inside a cylinder wall, implemented by using a device for laser shock peening inside a cylinder wall, characterized in that: The device comprises a laser (1), a half-wave plate (2), a polarizing plate (3), a focusing lens (4), a first displacement platform (5), a reflector (6), a water jet (7), an absorption layer spin coater (8), and a clamping platform (9); wherein the reflector (6), the water jet (7), and the absorption layer spin coater (8) are clamped on the same clamping platform (9) and connected to the second displacement platform (13) via an adapter; the clamping platform (9) is arranged inside the processing sample (11); the laser (1), the half-wave plate (2), the polarizing plate (3), the focusing lens (4), the first displacement platform (5), the reflector (6), the water jet (7), and the absorption layer spin coater (8) are arranged in sequence on the same optical axis The focusing lens (4) is mounted on the first displacement platform (5); the water jet (7) is connected to the water pump (12); during laser shock strengthening, the second displacement platform (13) translates or rotates along the optical axis direction, driving the reflector (6), the water jet (7), and the absorption layer spin coater (8) on the clamping platform (9) to move synchronously. At the same time, the laser (1) emits laser light, which is incident on the focusing lens (4) after passing through the half-wave plate (2) and the polarizing plate (3), and then is focused on the inner wall of the processed sample (11) after passing through the reflector (6). The water jet (7) sprays water to the focus position, and the absorption layer spin coater (8) spin coats the absorption layer (10) on the inner wall of the processed sample (11); The method specifically comprises the following steps: S1, a laser beam emitted by a laser (1) passes through a half-wave plate (2) and a polarizing plate (3) in sequence along a laser optical path, and then passes through a focusing lens (4) mounted on a first displacement platform (5) and a reflecting mirror (6) mounted on a clamping platform (9), and is focused and irradiated onto the inner wall surface of a processed sample (11). By adjusting the position of the first displacement platform (5), it is ensured that the laser focus always falls on the inner wall of the processed sample (11); S2, adjusting the half-wave plate (2) to adjust the incident laser to an incident laser energy density W within a set range, the absorption layer spin coater (8) spin coats the absorption layer (10) on the inner wall of the processed sample (11), the water jet (7) jets water at the laser focus as a constraint layer to achieve the conditions for laser shock peening processing of the inner wall of the sample (11), and then moving the second displacement platform (13) to perform laser shock peening processing on the longitudinal area depth of the processed sample (11); S3, after completing the laser shock peening of the depth of the longitudinal region at the current position, turn off the laser (1), the water jet (7) and the absorption layer spin coater (8), move the laser focus back to the entrance of the processed sample (11) by moving the second displacement platform (13), rotate the second displacement platform (13), move the laser focus to other lateral positions of the inner wall of the processed sample (11), and adjust the position of the focusing lens (4) by moving the first displacement platform (5) to ensure that the laser focus remains focused on the inner wall surface of the processed sample (11), and turn on the laser (1), the water jet (7) and the absorption layer spin coater (8) again to carry out laser shock peening of the longitudinal depth region at the new lateral position of the inner wall of the processed sample (11); S4, after repeating step S3 to complete the laser shock peening of all regions of the inner wall of the processed sample (11), the absorption layer spin-coated on the inner wall of the processed sample (11) is removed, thereby completing the laser shock peening of the inner wall of the processed sample (11); The incident laser energy density W within the set range described in S2 is obtained as follows: According to formula (1) and formula (2), the surface residual compressive stress generated by laser shock wave is Plastic influence depth Fitting and screening to obtain the laser shock wave peak pressure P range corresponding to 1-2.5 times HEL; Substitute the laser shock wave peak pressure P range corresponding to 1-2.5 times HEL into formula (3) to obtain the set incident laser density W range, so as to adjust the incident laser to the incident laser energy density W within the set range; （1） （2） （3） In the formula, is the Lamé constant, is the shear modulus, is the spot radius, is Poisson's ratio, and is the propagation speed of elastic waves and plastic waves in the material, is the pressure pulse width, a is the conversion coefficient of internal energy into thermal energy, and Z is the acoustic impedance.

2. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: The laser wavelength range of the laser (1) is 300nm-2000nm, and the laser energy adjustment range is 10μJ-100J.

3. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: The first displacement platform (5) is used to adjust the position of the focusing lens (4) so ​​that the focusing lens (4) is longitudinally translated along the optical axis, thereby ensuring that the focus is always focused on the surface of the inner wall of the processed sample (11).

4. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: The telescopic range of the first displacement platform (5) is 0-30m, and the accuracy range is 0.01-0.05mm.

5. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: The absorption layer (10) is made of black glue or black paint.

6. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: When the second displacement platform (13) is translated forward and backward along the optical axis direction, the longitudinal depth position of the reflector (6), the water jet (7), and the absorption layer spin coater (8) on the clamping platform (9) on the inner wall of the processed sample (11) is adjusted; when the second displacement platform (13) is rotated along the optical axis direction, the lateral position of the reflector (6), the water jet (7), and the absorption layer spin coater (8) on the clamping platform (9) on the inner wall of the processed sample (11) is adjusted.

7. The method for laser shock strengthening of the inner wall of a cylinder according to claim 1, characterized in that: The second displacement platform (13) has a telescopic range of 0-30 m, an accuracy range of 0.01-0.05 mm, a rotation range of 0-360 degrees, and an accuracy of 0.1-0.3 μrad.

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