A deep cooling laser shock device and method

Abstract

The present invention provides a device and method for deep-cold laser shock, which belongs to the field of deep-cold laser shock strengthening. It includes a cooling box, a transition chamber, a laser shock chamber and a general control system. The invention method is to first use the cooling box to cool the sample, use a low-temperature probe to detect the temperature of the sample in real time, and after the sample temperature stabilizes to the specified temperature, the gas in the box is drained, and the cooling box is moved to the laser shock chamber under a vacuum state, and the deep-cold laser shock is completed with the cooperation of a robotic arm and a three-dimensional motion platform. The characteristics and advantages of the present invention are: first, it avoids the problem of insufficient light transmittance caused by direct contact between liquid nitrogen and the sample, so that the sample can be deep-cold laser shock strengthened in a vacuum environment; in addition, metal materials can be deep-cold laser shock strengthened within the sample temperature range of 0℃ to ‑190℃; secondly, it is suitable for deep-cold laser shock strengthening of straight and curved surface samples; finally, the present invention is suitable for large-scale deep-cold laser shock, which can reduce the cost of shock strengthening.

Description

Technical Field

[0001] The present invention relates to the field of cryogenic laser shock strengthening, and in particular to a device and method for cryogenic laser shock strengthening a sample in a vacuum environment. Background Art

[0002] Laser shock peening, also known as laser shot peening, is a new surface strengthening process. Studies have shown that under ultra-low temperature conditions, the dislocation slip resistance of metal materials increases, which can effectively increase the threshold for the material to accommodate high-density dislocations. Laser shock peening of metal materials under deep-cold conditions can cause the material to produce more dislocations and deformation twins, and can produce a higher strain rate inside the material. Therefore, deep-cold laser shot peening can produce a better strengthening effect on the material, thereby significantly improving the strength and hardness of the metal material surface.

[0003] Currently, cryogenic laser shock peening involves lowering the material's temperature through heat conduction and then laser peening the sample. This process is primarily categorized into two types: fixed-temperature and controllable-temperature. Fixed-temperature shock peening involves immersing the sample in liquid nitrogen for laser shock. This method's temperature cannot be adjusted, making it difficult to study the relationship between the laser shock effect and temperature. Furthermore, liquid nitrogen absorbs heat and vaporizes, instantly generating a large amount of bubbles and white mist at room temperature, reducing light transmittance. A commonly used temperature control method involves continuously and intermittently delivering liquid nitrogen or nitrogen gas to the metal material. By controlling the output of liquid nitrogen or nitrogen gas, the sample is maintained at an adjustable low temperature for laser shock. However, this method wastes a significant amount of liquid nitrogen or nitrogen gas when cryogenic shocking a large number of samples, increasing costs. Furthermore, existing cryogenic laser shock peening is primarily targeted at straight-surfaced samples, while cryogenic laser shock peening of curved-surface samples remains a technological challenge. Summary of the Invention

[0004] The object of the present invention is to provide a device and method for cryogenic laser shock with controllable temperature in a vacuum environment.

[0005] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a deep-cold laser shock device, including a cooling box, a transition chamber and a laser shock chamber, the transition chamber is provided with a first automatic door and a second automatic door, the second automatic door is located between the transition chamber and the laser shock chamber, the transition chamber and the laser shock chamber are both connected to a vacuum pump through an exhaust hose, and a robotic arm and a laser shock strengthening device are provided in the laser shock chamber.

[0006] In the above scheme, the cooling box is located as a whole on the first conveyor belt, a one-dimensional motion platform is provided in the transition chamber, a second conveyor belt is installed on the one-dimensional motion platform, a two-dimensional motion platform is provided in the laser impact chamber, a third conveyor belt is installed on the two-dimensional motion platform, and the first conveyor belt, the second conveyor belt and the third conveyor belt are coplanar.

[0007] In the above solution, the cooling box includes an upper box body, a lower box body, a nitrogen bottle and a vacuum pump. The upper box body is connected to the lower box body rotating pair through a hinge, and the nitrogen bottle and the vacuum pump are connected to the lower box body through a pipeline system.

[0008] In the above solution, an electric lifting motor and a partition are provided in the lower box body. The electric lifting motor passes through the partition and is connected to a supporting plate in the partition. A low-temperature probe is installed on the supporting plate.

[0009] In the above scheme, the upper box body is provided with a box in-vivo device, and the box in-vivo device includes a hollow end cover, a first high-pressure resistant glass, a second high-pressure resistant glass, a pressure block and a second vacuum valve installed on one side of the outer wall of the upper box body. The second high-pressure resistant glass is tightly pressed and fixed in the light-transmitting hole of the upper box body by the pressure block; the hollow end cover and the upper box body are fastened by threads, and the first high-pressure resistant glass is tightly screwed onto the light-transmitting hole of the upper box body. The first high-pressure resistant glass and the second high-pressure resistant glass are installed inside the light-transmitting hole of the upper box body, and a gasket is installed on the contact surface with the upper box body.

[0010] In the above scheme, the piping system includes a pressure reducing valve, a quick connector, a second solenoid valve, a pressure relief valve, a first vacuum valve and a third vacuum valve. The pressure reducing valve is installed between the nitrogen cylinder and the quick connector, the second solenoid valve is installed on the top surface of the upper box body, and the quick connector is installed above the second solenoid valve. When the quick connector is disconnected, the box body and the metal hose can be separated; the pressure relief valve is installed on the top surface of the upper box body, and the first vacuum valve is installed on the top surface of the upper box body. When the sample temperature drops to the specified temperature T, the vacuum pump drains the air in the cooling chamber formed between the upper box body and the interlayer through the exhaust hose.

[0011] In the above solution, the upper box body is fixed with a lifting ear, the lower box body is fixed with a support block, one end of the movable connecting rod is movably connected to the lifting ear, and the other end is movably connected to the top of the electric push-pull rod, and the bottom of the electric push-pull rod is fixedly connected to the support block.

[0012] In the above scheme, the first automatic door, the second automatic door, the first solenoid valve, the vacuum pump, the first conveyor belt, the second conveyor belt, the one-dimensional motion platform, the third conveyor belt, the two-dimensional motion platform, the robotic arm, the three-dimensional motion platform, the pulse laser, the servo motor and the third solenoid valve are all connected to the first computer through the first controller; the low-temperature probe is connected to the second computer through the temperature sensor for real-time measurement of the sample temperature.

[0013] The present invention also provides a low-temperature laser shock method, comprising the following steps: S1, opening the upper box, raising the support plate, placing the sample with the absorption layer on the support plate, then lowering the support plate, and closing the upper box; S2, opening the pressure relief valve and the second solenoid valve through the low-temperature control device, controlling the gas flow of nitrogen input into the cooling chamber, and after the sample temperature stabilizes to T°C, controlling the second computer to close the pressure relief valve and the second solenoid valve, and then starting the vacuum pump to drain the air in the cooling chamber; after the gas in the cooling chamber is drained, disconnecting the quick connector and the exhaust hose, and placing the cooling box on the first conveyor belt; S3 The first automatic door is opened by the first computer, and the cooling box is transported from the first conveyor belt to the second conveyor belt, and then the first automatic door is closed, the first solenoid valve is opened, and the gas in the transition chamber is drained; S4 opens the second automatic door, transports the sample to the third conveyor belt, opens the upper box body through the box body movement device, raises the support plate, and then the robotic arm takes out the sample and transports it to a position where the end face of the impact head end cover is 15 to 25 mm away from the sample to be strengthened, adjusts the laser laser energy, spot diameter, frequency, pulse width and overlap rate, and then pre-impacts the laser shock chamber in a vacuum state for 2 minutes, and then performs laser shock strengthening; S5 After the shock strengthening is completed, the sample is placed on the support plate, and then the support plate is lowered, the upper box body is covered, and the cooling box is transported to the second conveyor belt, and then the second automatic door is closed, the first automatic door is opened, and the cooling box is transported to the first conveyor belt, and finally the sample is taken out. The entire impact process is completed, all equipment is turned off, and the next impact process only needs to repeat S1 to S5.

[0014] The beneficial effects of the present invention are as follows: (1) By continuously and controllably injecting low-temperature nitrogen into the cooling box, the sample is brought to a low temperature, and the temperature is fed back to the second computer control system in real time through the low-temperature probe and temperature sensor. When the temperature drops to the specified temperature, the cooling is stopped and the air in the box is evacuated to achieve controllable deep-cold temperature; the sample is placed in a vacuum environment for laser shock, which avoids heat conduction in the sample and achieves temperature-controlled deep-cold laser shock; a transition chamber is set in front of the laser shock chamber to reduce the amount of gas vacuum pumping; an automatic door, a mechanical motion device and a robotic arm are arranged to achieve deep-cold shock of curved surface samples and improve the efficiency of large-scale deep-cold shock. (2) The invention method is to first use the cooling box to cool the sample, use the low-temperature probe to detect the temperature of the sample in real time, and after the sample temperature stabilizes to the specified temperature, the gas in the box is evacuated, and the cooling box is moved to the laser shock chamber in a vacuum state. The deep-cold laser shock is completed with the cooperation of the robotic arm and the three-dimensional motion platform. First, the problem of insufficient light transmittance caused by direct contact between liquid nitrogen and the sample is avoided, so that the sample can be cryogenically laser shock strengthened in a vacuum environment; in addition, metal materials can be cryogenically laser shock strengthened within the sample temperature range of 0°C to -190°C; secondly, it is suitable for cryogenic laser shock strengthening of straight and curved surface samples; finally, the present invention is suitable for large-scale cryogenic laser shock strengthening, which can reduce the cost of shock strengthening. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the overall structure of the device of the present invention.

[0016] Figure 2 It is a structural diagram of the cooling box.

[0017] Figure 3 Schematic diagram of the laser transmission system.

[0018] Figure 4 This is a schematic diagram of the laser shock operation in progress.

[0019] Figure 1 Middle: 1. Cooling chamber, 2. Transition chamber, 3. Laser shock chamber, 4. First automatic door, 5. Pipe connector, 6. Second automatic door, 7. First solenoid valve, 8. Exhaust hose, 9. Vacuum pump, 10. First controller, 11. First computer, 12. Pipe connector, 13. Liquid nitrogen tank, 14. Metal hose, 15. First conveyor belt, 16. Second conveyor belt, 17. One-dimensional motion platform, 18. Third conveyor belt, 19. Two-dimensional motion platform, 20. Robotic arm, 21. Three-dimensional motion platform, 22. Fully reflective mirror, 23. Pulsed laser, 24. Transmission system, 25. Laser shock head.

[0020] Figure 2Middle: 1-1. Nitrogen cylinder, 1-2. Pressure reducing valve, 1-3. Connecting rod, 1-4. Hinge, 1-5. Lifting lug, 1-6. Metal hose, 1-7. Quick connector, 1-8. Second solenoid valve, 1-9. Hollow end cap, 1-10. Gasket, 1-11. First high-pressure resistant glass, 1-12. Second high-pressure resistant glass, 1-13. Pressure block, 1-14. Pressure relief valve, 1-15. First vacuum valve, 1-16. Exhaust hose, 1-17. Upper box, 1-18. Second vacuum valve, 1-19. Electric Push-pull rod, 1-20 supporting block, 1-21. Partition, 1-22. Lower box, 1-23. Support plate, 1-24. Plastic pad, 1-25. Electric lifting motor, 1-26. Low-temperature probe, 1-27. Connecting block, 1-28. Sample, 1-29. Absorption layer, 1-30. Controller with power supply, 1-31. Plastic strip, 1-32. Plastic pad, 1-33. Third vacuum valve, 1-34. Vacuum pump, 1-35. Temperature sensor, 1-36. Second controller, 1-37. Second computer.

[0021] Figure 3 Middle: 21. Three-dimensional motion platform, 21-1. Laser support block, 21-2. Fixed bracket, 24-1. Servo motor, 24-2. Driving pulley, 24-3. Driven pulley, 24-4. Long bearing, 24-5. Shaft shoulder, 24-6. Bolt, 24-7. Pressing block, 24-8. Hollow long shaft, 25-1. Third solenoid valve, 25-2. Impact head body, 25-3. Impact head end cover, 25-4. Fastening nut, 25-5. Small full-reflection mirror, 25-6. Full-reflection mirror support bracket, 25-7. T-shaped glass block, 25-8. Plastic gasket. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0023] like Figure 1 As shown, a cryogenic laser shock device provided in this embodiment includes a cooling box 1, a transition chamber 2, a laser shock chamber 3 and a general control system.

[0024] like Figure 2As shown, the cooling box 1 includes a low-temperature control device, a box movement device, a box internal viewing device and a second computer control system; the low-temperature control device is composed of a high-pressure nitrogen bottle 1-1, a pressure reducing valve 1-2, a quick connector 1-7, a second solenoid valve 1-8, a pressure relief valve 1-14, a first vacuum valve 1-15, a third vacuum valve 1-33, a vacuum pump 1-34 and a low-temperature probe 1-26 installed inside the support plate 1-23. The pressure reducing valve 1-2 is installed between the nitrogen bottle 1-1 and the quick connector 1-7 to control the gas flow of nitrogen input into the cooling box 1; the second solenoid valve 1-8 is installed on the top surface of the upper box 1-17 to close the inflow of nitrogen after the sample 1-28 is cooled to the specified temperature; the quick connector 1-7 is installed above the second solenoid valve 1-8, and when the quick connector is disconnected, the box can be separated from the metal hose 1-6; the pressure relief valve 1-14 is installed on the top surface of the upper box 1-17 to discharge the nitrogen that absorbs heat and expands inside the box air; the first vacuum valve 1-15 is installed on the top surface of the upper box body 1-17. When the temperature of the sample 1-28 drops to the specified temperature T, the vacuum pump 1-34 can drain the air in the cooling chamber formed between the upper box body 1-17 and the interlayer 1-21 through the exhaust hose 1-16; a plastic pad 1-32 is installed between the interlayer 1-21 and the lower box body 1-22 to achieve a sealed connection; the low-temperature probe 1-26 is connected to the second computer 1-37 through the temperature sensor 1-35 for real-time measurement of the temperature of the sample 1-28;

[0025] The box movement device includes an electric push-pull rod 1-19, a support block 1-20, a movable connecting rod 1-3, a hinge 1-4, a lifting lug 1-5, an electric lifting motor 1-25, and a connecting block 1-27 installed between the electric lifting motor 1-25 and the supporting plate 1-23. The support block 1-20 is installed on the side of the lower box 1-22; the lifting lug 1-5 is installed on the side of the upper box 1-17, on the same side as the support block 1-20; one end of the movable connecting rod 1-3 is movably connected to the lifting lug 1-5, and the other end is movably connected to the top of the electric push-pull rod 1-19; the bottom of the electric push-pull rod 1-19 is fixedly connected to the support block 1-20; the bottom of the electric lifting motor 1-25 is connected to the inner wall of the lower box 1-22, and the joint surface between the two is fixed. A plastic pad 1-24 is installed in the middle; the hinge is located between the upper and lower boxes to ensure that the upper box 1-17 can be opened and closed normally; the connecting block 1-27 is used to connect the electric lifting motor 1-25 and the supporting plate 1-23, so that the supporting plate 1-23 can be driven up and down when the lifting column is raised and lowered; the box movement device is controlled by the second computer 1-37, which can control the opening and closing of the upper box 1-17, as well as the lifting and lowering of the supporting plate 1-23 connected to the electric lifting motor 1-25.

[0026] The box in-vivo viewing device includes a hollow end cover 1-9, a first high-pressure resistant glass 1-11, a second high-pressure resistant glass 1-12, a pressing block 1-13, and a second vacuum valve 1-18 installed on one side of the outer wall of the upper box body 1-17; the box in-vivo viewing device is used to observe the sample 1-28 inside the box body during cooling, wherein the second high-pressure resistant glass 1-12 is tightly pressed and fixed in the light-transmitting hole of the upper box body 1-17 by the pressing block 1-13; the hollow end cover 1-9 is fastened to the upper box body 1-17 by screw threads, and the first high-pressure resistant glass is tightly screwed onto the light-transmitting hole of the upper box body 1-17; the first 1-11 and the second high-pressure resistant glass 1-12 are installed in the light-transmitting hole of the upper box body 1-17, and are in contact with the upper box body. A gasket 1-10 is installed on the contact surface of 1-17; a second vacuum valve 1-18 on the outer wall of the upper box body 1-17 is used to drain the air between the first and second high-pressure resistant glasses to prevent fog or ice from forming on the first high-pressure resistant glass 1-11 due to low temperature, which affects the observation of the sample 1-28 in the cooling box 1; the second solenoid valve 1-8, the electric push-pull lever 1-19, and the electric lifting motor 1-25 are all wirelessly connected to the second computer 1-37 through a controller 1-30 with a power supply, and the controller 1-30 with a power supply is installed on the outer wall of the lower box body 1-22; the pressure reducing valve 1-2 and the vacuum pump 1-34 are connected to the second computer 1-37 through the second controller 1-36;

[0027] The transition chamber 2 includes a second conveyor belt 16 and a one-dimensional motion platform 17. The one-dimensional motion platform 17 can move left and right to enable the second conveyor belt 16 installed on the one-dimensional motion platform 17 to dock with the first conveyor belt 15 and the third conveyor belt 18 respectively, so that the cooling box 1 can be transported from the first conveyor belt 15 to the third conveyor belt 18 when the first automatic door 4 and the second automatic door 6 are opened.

[0028] The laser shock chamber 3 includes a third conveyor belt 18, a two-dimensional motion platform 19, a robotic arm 20, a three-dimensional motion platform 21 and a laser shock device; the laser shock device is composed of liquid nitrogen 13, a metal hose 14, a full-reflection mirror 22, a pulse laser 23, a transmission system 24, and a laser shock head 25; wherein the pulse laser 23, the transmission system 24, and the laser shock head 25 are installed on the three-dimensional motion platform 21; the third conveyor belt 18 is installed on the two-dimensional motion platform 19; in the laser shock chamber 3, on the side of the second automatic door 6, a two-dimensional motion platform 19, a robotic arm 20 and a three-dimensional motion platform 21 are installed in sequence; the two-dimensional motion platform 19 can be moved forward, backward, left and right The two-dimensional movement on the right enables the cooling box 1 to dock with the robotic arm 20; by installing a specific thermal insulation fixture on the robotic arm 20, the sample 1-28 of the cooling box 1 can be taken out, and under the action of the laser impact device and the three-dimensional motion platform 21, the sample 1-28 is subjected to low-temperature laser shock strengthening; the first automatic door 4, the second automatic door 6, the first solenoid valve 7, the vacuum pump 9, the first conveyor belt 15, the second conveyor belt 16, the one-dimensional motion platform 17, the third conveyor belt 18, the two-dimensional motion platform 19, the robotic arm 20, the three-dimensional motion platform 21, the pulse laser 23, the servo motor 24-1 and the third solenoid valve 25-1 are all connected to the first computer 11 through the first controller 10.

[0029] The overall control system includes a first controller 10, a first computer 11, a controller 1-30 with a power supply, a second controller 1-36, and a second computer 1-37.

[0030] like Figure 3 and Figure 4 As shown, the transmission system 24 includes a servo motor 24-1, a driving wheel 24-2, a driven wheel 24-3, a long bearing 24-4 and a hollow long shaft 24-8; the bottom of the servo motor 24-1 is fixedly connected to the fixed frame 21-2, and the motor output shaft is tightly connected to the driving wheel 24-2; the driven wheel 24-3 is meshed with the driving wheel 24-2 for movement, and the inner ring of the driven wheel 24-3 is tightly connected to the outer wall of the hollow long shaft 24-8, so that when the driven wheel 24-3 rotates Drive the hollow long shaft 24-8 to rotate together; the end faces of the two long bearings 24-4 are restricted by the shaft shoulder 24-5 and are fixed on the hollow long shaft 24-8, the inner ring of the long bearing 24-4 is tightly fitted with the hollow long shaft, and the outer ring is fixed to the fixing frame 21-2 by the combined action of the clamping block 24-7 and the bolt 24-6; the fixing frame 21-2 is fixed on the lifting block of the three-dimensional motion platform 21, and can drive the hollow long shaft 24-8 and the laser impact head 25 to move up and down.

[0031] The laser impact head 25 includes a third solenoid valve 25-1, an impact head body 25-2, an impact head end cover 25-3, a small full-reflection mirror 25-5, a full-reflection mirror support frame 25-6 and a T-shaped glass block 25-7; the laser impact head 25 is fixed to one end of the hollow long shaft 24-8 by a fastening nut 25-4; the third solenoid valve 25-1 is installed on the impact head body 25-2, and can control the flow of liquid nitrogen flowing out of the liquid nitrogen tank 13 through the metal hose 14; the impact head end cover 25-3 is installed on the impact head body 25-2 through threaded cooperation. The size of the center hole of the end cover can be replaced according to the size of the laser spot. The center of the small total reflection mirror 25-5 coincides with the center line of the hollow long axis 24-8. The small total reflection mirror is fixed in the impact head body 25-2 at an angle of 45° through the total reflection mirror support frame 25-6. The T-shaped glass block 25-7 is installed in the impact head body 25-2 to ensure that liquid nitrogen is ejected from the center hole of the impact head end cover 25-3.

[0032] Furthermore, the third vacuum valve 1-33 is mounted on the outer wall of the lower chamber 1-22. Before cooling the sample 1-28, a vacuum pump and an exhaust hose are used to evacuate the air from the vacuum chamber formed between the interlayer 1-21 and the lower chamber 1-22. This vacuum chamber reduces heat conduction within the chamber. Furthermore, before placing the sample 1-28 in the cooling chamber 1, an absorbing layer is applied to the area to be laser-strengthened. This absorbing layer is made of black paint and has a thickness of less than 20 μm. Furthermore, the temperature T of the sample 1-28 within the cooling chamber 1 can be controlled to any temperature between 0°C and -190°C. Furthermore, the cooling status of the sample 1-28 within the cooling chamber 1 can be monitored at any time using the endoscope device in the upper chamber 1-17. Furthermore, the support plate 1-23 is drilled with several small holes to facilitate nitrogen flow. It is made of plastic and its length is shorter than the inner wall of the interlayer 1-21. Furthermore, there are two movable connecting rods 1-3, hinges 1-4, lifting lugs 1-5, electric push-pull levers 1-19, and support blocks 1-20, each mounted at the front and rear ends of the cooling box 1. Furthermore, the transmission ratio between the driving wheel 24-2 and the driven wheel 24-3 is 36:1. By controlling the rotation angle of the servo motor 24-1, the rotation angle of the hollow shaft 24-8 and the laser impact head 25 can be precisely controlled. Furthermore, the diameter D of the center hole of the impact head end cap 25-3 can be controlled to any size between 2 and 10 mm; the diameter D of the center hole of the impact head end cap (25-3) should be larger than the spot diameter d. Furthermore, the vacuum pump 9 is connected to the transition chamber 2 and the laser shock chamber 3 respectively through the exhaust hose 8, and the first solenoid valve 7 is installed on the exhaust hose 8 of the transition chamber 2; when the first automatic door 4 is opened and the second conveyor belt 16 on the one-dimensional motion platform 17 is docked with the first conveyor belt 15, the first solenoid valve 7 is closed and the vacuum pump 9 stops vacuuming the transition chamber 2; before the first automatic door 4 is closed and the second automatic door 6 is opened, the first solenoid valve 7 is connected and the vacuum pump 9 vacuums the transition chamber 2. After the gas in the transition chamber 2 is drained, the second automatic door 6 is opened, and the second conveyor belt 16 on the one-dimensional motion platform 17 is docked with the third conveyor belt 18, so that the cooling box 1 on the second conveyor belt 16 can be docked and transported to the third conveyor belt 18 under a vacuum state. Furthermore, the vacuum pump 9 continuously evacuates the laser shock chamber 3 to ensure that the laser shock chamber 3 is continuously in an empty state, and almost no heat conduction occurs in the sample 1-28; after the cooling box 1 enters the laser shock chamber 3, the electric push-pull rod 1-19 contracts, and the upper box body 1-17 is driven to open through the movable connecting rod 1-3, and the robotic arm takes out the sample 1-28 for impact strengthening operation.Furthermore, during the impact peening operation, the three-dimensional motion platform 21 is responsible for controlling the vertical and circular motion of the laser impact head 25. The robotic arm 20 is responsible for ensuring that the surface of the sample 1-28 to be peened is perpendicular to the centerline of the center hole of the impact head end cap 25-3, and for maintaining a certain distance between the end face of the impact head end cap 25-3 and the surface of the sample 1-28 to be peened. Furthermore, during the laser shock peening operation, the end face of the impact head end cap 25-3 maintains a distance of 15 to 25 mm from the surface of the sample 1-28 to be peened. When the third solenoid valve 25-1 is opened, the laser shock chamber 3 is in a vacuum state, allowing liquid nitrogen to be ejected from the center hole of the impact head end cap 25-3. Furthermore, after the absorption layer 1-29 absorbs the laser energy emitted by the pulse laser 23, a local plasma explosion occurs. By controlling the opening frequency and opening time difference of the pulse laser 23 and the third solenoid valve 25-1, the laser and liquid nitrogen can reach the surface of the sample 1-28 at the same time, thereby constraining the laser-induced shock wave. In a vacuum environment, liquid nitrogen will evaporate instantly after each enhanced impact, and the contact time between the liquid nitrogen and the sample 1-28 is extremely short, and there is no time for heat conduction between the two, so the sample 1-28 still maintains the temperature when it is taken out of the cooling box 1; the opening frequency of the pulse laser 23 and the third solenoid valve 25-1 must be consistent, and the said opening time difference can be measured by special equipment before impact enhancement and uniformly controlled by the first computer 11.

[0033] This example uses Al alloy as an example. Laser shock testing is performed using a cryogenic laser shock apparatus described in this example. The specific steps include: A. Using a hollow pipe with an inner diameter of 140 mm, a wall thickness of 4 mm, and a length of 220 mm as the sample, the upper housing 1-17 is opened using the housing movement device, the support plate 1-23 is raised, and the sample 1-28 coated with 18 μm thick black paint is placed on the support plate 1-23. The support plate 1-23 is then lowered, and the upper housing 1-17 is closed. B. The pressure relief valve 1-14 and the second solenoid valve 1-8 are opened through the low-temperature control device, and high-pressure nitrogen is first input into the cooling chamber at a flow rate of 10 L / min. When the temperature of the sample 1-28 reaches -160°C, the flow rate of nitrogen is halved. When the temperature of the sample 1-28 reaches -170°C, the pressure relief valve 1-14 is closed to stop the nitrogen input, and the temperature is kept warm for 2 minutes. During this period, if the temperature of the sample 1-28 is higher than -170°C, nitrogen is input again at a rate of 5 L / min until the temperature of the sample 1-28 stabilizes at -170°C. Then, the second computer 1-37 is controlled to close the pressure relief valve 1-14 and the second solenoid valve 1-8, and the vacuum pump 1-34 is activated to drain the air from the cooling chamber. The quick connector 1-7 and the exhaust hose 1-16 are disconnected, and the cooling chamber 1 is placed on the first conveyor belt 15. C. The first computer 11 opens the first automatic door 4, transporting the cooling chamber 1 to the second conveyor belt 16. The first automatic door 4 is then closed, and the first solenoid valve 7 is opened to drain the air from the transition chamber 2. D. After the transition chamber 2 reaches a vacuum state, the second automatic door 6 is opened, and the sample 1-28 is transported to the third conveyor belt 18. The upper box 1-17 is opened by the box movement device, and the support plate 1-23 is raised. Then, the robotic arm 20 equipped with a thermal insulation clamp removes the sample 1-28 and transports it to a position 20 mm away from the end face of the impact head end cover 25-3 on the outer wall of the pipeline. The laser energy is adjusted to 10 J, the spot diameter is 3 mm, the frequency is 1 Hz, and the overlap rate is 50%; E. The time difference between the liquid nitrogen and the laser reaching the surface to be strengthened at the same time, which was measured in advance by special equipment, is input into the first computer 11, and the opening frequency of the third solenoid valve 25-1 is adjusted to 1 Hz. The robotic arm is responsible for circular motion, and the laser impact head is responsible for up and down motion. Pre-impact for 2 minutes is performed, and then laser impact strengthening of the outer wall of the pipeline is started; F. After the pipeline completes one circle of impact, the next circle of impact is repeated again until the entire area to be strengthened is completed.

[0034] The above embodiments are preferred implementations of the present invention, but the present invention is not limited to them. For example, when laser shock peening the inner wall of a pipe, only the robotic arm is responsible for the up-and-down motion, while the laser shock head is responsible for the circular motion. Any obvious improvements, substitutions, or modifications that can be made by those skilled in the art without departing from the essence of the present invention and without departing from the principles and purpose of the present invention are within the scope of protection of the present invention.

Claims

1. A cryogenic laser shock device, characterized in that: The invention comprises a cooling box (1), a transition chamber (2) and a laser shock chamber (3), wherein the transition chamber (2) is provided with a first automatic door (4) and a second automatic door (6), the second automatic door (6) is located between the transition chamber (2) and the laser shock chamber (3), the transition chamber (2) and the laser shock chamber (3) are both connected to a vacuum pump (9) through an exhaust hose (8), and a robotic arm (20) and a laser shock strengthening device are provided in the laser shock chamber (3); the cooling box (1) is located on a first conveyor belt (15) as a whole, and a one-dimensional motion platform (17) is provided in the transition chamber (2), and a second conveyor belt (15) is installed on the one-dimensional motion platform (17). The laser impact chamber (3) is provided with a two-dimensional motion platform (19), a third conveyor belt (18) is installed on the two-dimensional motion platform (19), and the first conveyor belt (15), the second conveyor belt (16) and the third conveyor belt (18) are coplanar; the cooling box (1) comprises an upper box body (1-17), a lower box body (1-22), a nitrogen bottle (1-1) and a vacuum pump (1-34), the upper box body (1-17) is connected to the lower box body (1-22) through a hinge (1-4) and a rotating pair, and the nitrogen bottle (1-1) and the vacuum pump (1-34) are connected to the lower box body (1-22) through a pipeline system.

2. The cryogenic laser shock device according to claim 1, characterized in that: An electric lifting motor (1-25) and a partition (1-21) are provided in the lower box body (1-22); the electric lifting motor (1-25) passes through the partition (1-21) and is connected to a supporting plate (1-23) in the partition; a low-temperature probe (1-26) is installed on the supporting plate (1-23).

3. The cryogenic laser shock device according to claim 2, characterized in that: The upper box body (1-17) is provided with a box in-penetration device, which comprises a hollow end cover (1-9), a first high-pressure resistant glass (1-11), a second high-pressure resistant glass (1-12), a pressing block (1-13), and a second vacuum valve (1-18) installed on one side of the outer wall of the upper box body (1-17); the second high-pressure resistant glass (1-12) is tightly pressed and fixed in the light-transmitting hole of the upper box body (1-17) by the pressing block (1-13); the hollow end cover (1-9) and the upper box body (1-17) are fastened by threads, and the first high-pressure resistant glass is tightly screwed onto the light-transmitting hole of the upper box body (1-17); the first high-pressure resistant glass (1-11) and the second high-pressure resistant glass (1-12) are installed inside the light-transmitting hole of the upper box body (1-17), and a gasket (1-10) is installed at the contact surface with the upper box body (1-17).

4. The cryogenic laser shock device according to claim 3, characterized in that: The pipeline system comprises a pressure reducing valve (1-2), a quick connector (1-7), a second solenoid valve (1-8), a pressure relief valve (1-14), a first vacuum valve (1-15) and a third vacuum valve (1-33), wherein the pressure reducing valve (1-2) is installed between the nitrogen cylinder (1-1) and the quick connector (1-7), the second solenoid valve (1-8) is installed on the top surface of the upper box (1-17), and the quick connector (1-7) is installed above the second solenoid valve (1-8). When the quick connector (1-7) is disconnected, the box body and the metal hose (1-6) can be separated; the pressure relief valve (1-14) is installed on the top surface of the upper box body (1-17), and the first vacuum valve (1-15) is installed on the top surface of the upper box body (1-17). When the temperature of the sample (1-28) is reduced to a specified temperature T, the vacuum pump (1-34) evacuates the air in the cooling chamber formed between the upper box body (1-17) and the interlayer (1-21) through the exhaust hose (1-16).

5. The cryogenic laser shock device according to claim 4, characterized in that: The upper box body (1-17) is fixed with a lifting lug (1-5), the lower box body (1-22) is fixed with a supporting block (1-20), one end of the movable connecting rod (1-3) is movably connected to the lifting lug (1-5), and the other end is movably connected to the top of the electric push-pull rod (1-19), and the bottom of the electric push-pull rod (1-19) is fixedly connected to the supporting block (1-20).

6. The cryogenic laser shock device according to claim 5, characterized in that: The first automatic door (4), the second automatic door (6), the first solenoid valve (7), the vacuum pump (9), the first conveyor belt (15), the second conveyor belt (16), the one-dimensional motion platform (17), the third conveyor belt (18), the two-dimensional motion platform (19), the robotic arm (20), the three-dimensional motion platform (21), the pulse laser (23), the servo motor (24-1) and the third solenoid valve (25-1) are all connected to the first computer (11) through the first controller (10); the low-temperature probe (1-26) is connected to the second computer (1-37) through the temperature sensor (1-35) for real-time measurement of the temperature of the sample (1-28).

7. A method for performing low-temperature laser shock using the cryogenic laser shock device according to claim 6, characterized in that: The following steps are included: S1. Open the upper box (1-17), raise the supporting plate (1-23), place the sample (1-28) provided with the absorption layer (1-29) on the supporting plate (1-23), then lower the supporting plate (1-23), and close the upper box (1-17); S2 opens the pressure relief valve (1-14) and the second solenoid valve (1-8) through the low-temperature control device to control the gas flow of nitrogen input into the cooling chamber. After the temperature of the sample (1-28) stabilizes to T℃, the second computer (1-37) is controlled to close the pressure relief valve (1-14) and the second solenoid valve (1-8), and then the vacuum pump (1-34) is turned on to drain the air in the cooling chamber. After the gas in the cooling chamber is drained, the quick connector (1-7) and the exhaust hose (1-16) are disconnected, and the cooling box (1) is placed on the first conveyor belt (15); S3 opens the first automatic door (4) through the first computer (11), transports the cooling box (1) from the first conveyor belt (15) to the second conveyor belt (16), then closes the first automatic door (4), opens the first solenoid valve (7), and drains the gas in the transition chamber (2); S4 opens the second automatic door (6), transports the sample (1-28) to the third conveyor belt (18), opens the upper box (1-17) through the box movement device, lifts the support plate (1-23), and then the robot arm (20) takes out the sample (1-28), transports it to a position where the end face of the impact head end cover (25-3) is 15 to 25 mm away from the sample to be strengthened (1-28), adjusts the laser energy, spot diameter, frequency, pulse width and overlap rate, and then pre-impacts it in the laser shock chamber (3) under vacuum for 2 minutes, and then performs laser shock strengthening; After the S5 impact strengthening is completed, the sample (1-28) is placed on the support plate (1-23), and then the support plate (1-23) is lowered, the upper box body (1-17) is covered, and the cooling box (1) is transported to the second conveyor belt (16). Then the second automatic door (6) is closed, the first automatic door (4) is opened, and the cooling box (1) is transported to the first conveyor belt (15). Finally, the sample (1-28) is taken out. The entire impact process is completed, and all equipment is turned off. The next impact process only needs to repeat S1 to S5.

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