Laser shock forming apparatus and method with adjustable absorption layer

Abstract

The application relates to a laser shock forming device and method with adjustable absorption layer, which comprises a magnetic field force applying system, a working groove and a laser shot forming system. A part of the magnetic field force applying system is tightly attached to the upper side of the working groove to seal the liquid in the working groove, and the laser shot forming system is located above the working groove. The magnetic field force applying system controls the current size and direction to adjust the direction and size of the magnetic field generated by the coil, and then generates different force applying conditions for the annular magnet. The application utilizes the characteristics that the magnetic field generated by the energized coil and the annular magnet will generate force to extrude the liquid in the working groove, so that the thickness of the liquid absorption layer can be adjusted, and the application can be applied to various large-size high-end structural parts with variable thickness.

Description

Technical Field

[0001] This invention belongs to the field of laser shock forming, and specifically relates to a laser shock forming apparatus and method with an adjustable absorption layer. Background Technology

[0002] Laser peening is a novel, flexible, precision, moldless forming method. It involves sequentially covering the workpiece surface with an absorption layer and a constraint layer. A laser beam penetrates the constraint layer and irradiates the workpiece perpendicularly. The laser is absorbed by the absorption layer, causing it to vaporize, ionize, explode, and expand, inducing a high-pressure plasma shock wave on the workpiece surface. This ultra-high-pressure plasma shock wave acts on the workpiece surface, and the high-energy laser beam impacts the sheet metal point-by-point, causing compressive plastic deformation. Utilizing the plastic ductility and extensibility of metals, small deformations accumulate to form large macroscopic deformations. It has been widely applied in aerospace, space science, and marine engineering.

[0003] The absorption layer is used to absorb laser energy and protect the workpiece surface. In current laser shock processing, the absorption layer must be pre-sprayed or pre-applied before the laser shock process. After a laser pulse acts on the absorption layer, it is ablated, vaporized, and ionized, generally thinning or completely destroying its thickness. If multiple continuous laser shocks are required at the same point, or high-density continuous laser shocks per unit area, the force of each shock varies due to the different thicknesses of the absorption layer. The cumulative effect of these errors significantly impacts the forming accuracy of the workpiece, and the surface of the workpiece without the protection of the absorption layer will also be ablated and damaged by the laser. Therefore, in practical applications, when the absorption layer becomes thinner or damaged, to avoid ablation and damage to the workpiece surface or to ensure the shock effect, a thicker absorption layer is usually used, or the absorption layer is re-sprayed or reapplied offline. This method is impractical, inefficient, and fails to solve the problem of low precision. Summary of the Invention

[0004] In view of the defects and deficiencies in the existing technology, the present invention provides a laser shock forming apparatus and method with adjustable absorption layer. The apparatus is suitable for applications involving multiple continuous laser shocks at the same point or high-density continuous laser shock processing.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: a laser shock forming device with adjustable absorption layer, comprising an optical path system consisting of a nanosecond laser, a reflector, and a focusing lens. A working groove is provided below the focusing lens, and a slider is provided on the inner wall of the working groove. The slider is connected to the inner wall of the working groove via a sliding pair. The slider is fixed on a clamping block, and a ring magnet is nested inside the clamping block. The ring magnet is connected to a magnetic field force application system. Optical glass is installed on both the upper and lower sides of the clamping block. The working groove is fixed as a whole on an xyz three-axis machining platform. A constraint medium is contained in the working groove, and an absorption medium conveying system is installed on the groove wall of the working groove.

[0006] In the above scheme, the magnetic field force application system includes a circuit system consisting of a controllable DC power supply, a commutator, and a coil, with the coil located above the annular magnet.

[0007] In the above scheme, the absorption medium conveying system includes a flow valve, a first liquid storage tank, a hydraulic pump, a second liquid storage tank, and a safety valve connected in sequence. The flow valve and the safety valve are both connected to the working tank through pipelines.

[0008] In the above scheme, an ultrasonic vibrator, a temperature controller and a pressure sensor probe are also installed in the working tank. A first three-dimensional information collector and a second three-dimensional information collector are installed outside the working tank. The first three-dimensional information collector is angled towards the processing indicator of the workpiece to be processed, and the second three-dimensional information collector is flush with the upper surface of the workpiece to be processed.

[0009] In the above scheme, the safety valve is connected to the computer through a safety valve threshold controller, the ultrasonic vibrator is connected to the computer through an ultrasonic controller, the xyz three-axis machining platform is connected to the computer through a motion controller, the pressure sensor probe is connected to the computer through a pressure sensor, and the temperature controller, the flow valve, the hydraulic pump, the controllable DC power supply, the commutator, and the nanosecond laser are all connected to the computer.

[0010] In the above scheme, the density of the liquid absorption medium is greater than that of the liquid confinement medium, and the two are immiscible.

[0011] In the above scheme, the nanosecond laser uses a Gaussian spot with a spot diameter of 5-8 mm and a laser energy of 50-100 J, and the flow rate of the flow valve is 5-20 cm3 / min.

[0012] This invention also provides a method for laser shock forming using a laser shock forming apparatus, comprising the following steps: S1: Injecting an appropriate amount of liquid absorbing medium and liquid constraining medium into a working tank, placing a workpiece inside, and placing a rectangular pressure plate with a ring magnet on the liquid constraining layer; S2: Opening the flow valve, safety valve, and second three-dimensional information acquisition device, and activating the safety valve threshold controller to adjust the threshold of the safety valve so that the liquid interface is slightly higher than the upper surface of the workpiece; S3: Adjusting the voltage of the controllable DC power supply and the position of the commutator, and applying pressure to the constraining medium by changing the force exerted on the ring magnet by the magnetic field generated by the coil, thereby adjusting the liquid height of the absorbing medium; S4: Activating the ultrasonic vibrator, temperature controller, pressure sensor probe, three-dimensional information acquisition device, workpiece to be processed, xyz three-axis machining platform, and nanosecond laser to process the workpiece. During the interval between two shocks, it is necessary to ensure that the first three-dimensional information acquisition device observes no bubbles above the workpiece, and that the pressure sensor shows no significant fluctuations.

[0013] The beneficial effects of this invention are as follows: (1) This invention utilizes the characteristic that the magnetic field generated by the energized coil and the force generated by the ring magnet are used to squeeze the liquid in the working tank, thereby adjusting the thickness of the liquid absorption layer. It is applicable to various large-size variable-thickness high-end structural parts. (2) The safety valve threshold is adjustable, which can quickly adjust the height of the liquid absorption layer. It is flexibly applicable to large-size variable-thickness high-end structural parts, greatly saving efficiency. (3) By controlling the magnitude and direction of the coil current to change the pressure on the ring magnet, the height of the absorption layer during laser shot peening can be flexibly fine-tuned, greatly improving the forming accuracy. (4) The use of an ultrasonic vibrator and temperature controller avoids the interference of liquid thermal expansion and bubbles on the laser beam, ensuring the stability of the processing environment variables. (5) The liquid absorption layer can be recycled, which is economical and sustainable. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the device of the present invention.

[0015] In the diagram: 1-Controllable DC power supply, 2-Commutator, 3-Nanosecond laser, 4-Reflector, 5-Coil, 6-Computer, 7-Focusing lens, 8-Ring magnet, 9-Optical glass, 10-Clamping block, 11-Slider, 12-Ultrasonic controller, 13-Ultrasonic vibrator, 14-Liquid confinement medium, 15-Flow valve, 16-Second 3D information acquisition device, 17-Temperature controller, 18-First 3D information acquisition device, 19-First liquid storage tank, 20-Pressure sensor, 21-Pressure sensor probe, 22-Workpiece to be processed, 23-XYZ three-axis machining platform, 24-Liquid absorption medium, 25-Hydraulic pump, 26-Motion controller, 27-Safety valve, 28-Second liquid storage tank, 29-Safety valve threshold controller. Detailed Implementation

[0016] The technical solution of the present invention will be described in more detail below with reference to the accompanying drawings.

[0017] The laser shock forming apparatus provided by this invention includes a magnetic field force application system, a working tank, and a laser shot peening forming system. The magnetic field force application system is closely attached to the upper surface of the working tank, and the laser shot peening forming system is located on the upper surface of the working tank and in the middle of the magnetic field force application system. The magnetic field force application system includes a controllable DC power supply 1, a commutator 2, a coil 5, a ring magnet 8, an optical glass 9, a clamping block 10, and a slider 11. The working tank contains a liquid confinement medium 14, a liquid absorption medium 24, an ultrasonic vibrator 13, a temperature controller 17, a three-dimensional information acquisition device 18, a pressure sensor probe 21, a workpiece to be processed 22, and an xyz three-axis machining platform 23. It is also equipped with an external flow control valve 15, a second three-dimensional information acquisition device 16, a liquid storage tank 19, a hydraulic pump 25, a safety valve 27, and other equipment.

[0018] The controllable DC power supply 1 and commutator 2 are connected to coil 5, which can change the magnitude and direction of the current to generate magnetic fields of different magnitudes and directions. The ring magnet 8 drives the optical glass 9 to be in close contact with the surface of the liquid confinement medium 14 and parallel to the coil 5.

[0019] The slider 11 is bonded to the clamping block 10 and connected to the annular magnet 8. The side of the slider 11 that is against the wall is smooth and coated with lubricant, so that the friction with the wall surface can be ignored and there is no gap to allow the liquid constraint layer 14 to flow out.

[0020] The working tank, safety valve 27, second liquid storage tank 28, hydraulic pump 25, first liquid storage tank 19, and working tank are connected by pipelines in sequence, and the liquid absorption medium 24 circulates in them.

[0021] The nanosecond laser 3 uses a Gaussian spot with a diameter of 5-8 mm and a laser energy of 50-100 J. The flow rate of the flow valve 15 is 5-20 cm. 3 / min.

[0022] The present invention also provides a laser shock forming method for the above-mentioned laser shock forming apparatus, comprising the following steps: S1 Injecting an appropriate amount of liquid absorbing medium 24 and liquid confinement medium 14 into the working tank, and placing the workpiece 22 to be processed in the tank, and placing the optical glass 9 below the rectangular pressure plate with the annular magnet 8 above the liquid confinement layer 14; S2 Opening the flow valve 15, the safety valve 27, and the second three-dimensional information acquisition device 16, and activating the safety valve threshold controller 29 to adjust the threshold of the safety valve 27 so that the liquid interface is slightly higher than the upper surface of the workpiece 22 to be processed; S3 Adjusting the voltage of the controllable DC power supply 1 and the position of the commutator 2, and changing the output of the coil 5 The magnetic field exerted on the annular magnet 8 is used to fine-tune the interface between the liquid confinement layer 14 and the liquid absorption medium 24. Since the density of the liquid absorption layer 24 is greater than that of the liquid confinement layer 14 and they are immiscible, the height of the liquid absorption layer 24 is adjusted by compressing the liquid confinement layer 14. In step S4, the ultrasonic vibrator 13, temperature controller 17, pressure sensor probe 21, three-dimensional information acquisition device 18, workpiece 22 to be processed, xyz three-axis machining platform 23, and nanosecond laser 3 are activated to process the workpiece 22. The ultrasonic vibrator 13 promotes slow liquid flow to avoid localized high temperatures and bubble annihilation. The pressure sensor probe 21 is used to monitor whether the liquid pressure is stable to determine whether the inflow and outflow velocities have reached a steady-state equilibrium. During the interval between two impacts, it is necessary to ensure that the first three-dimensional information acquisition device 18 observes no bubbles above the workpiece 22 and that the pressure sensor 20 shows no significant fluctuations.

[0023] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A laser shock forming apparatus with an adjustable absorption layer, comprising an optical path system consisting of a nanosecond laser (3), a reflector (4), and a focusing lens (7), characterized in that, A working groove is provided below the focusing lens (7). A slider (11) is provided on the inner wall of the working groove. The slider (11) is connected to the inner wall of the working groove via a sliding pair. The slider (11) is fixed on the clamping block (10). A ring magnet (8) is nested inside the clamping block (10). The ring magnet (8) is connected to the magnetic circuit of the magnetic field force application system. Optical glass (9) is installed on both the upper and lower sides of the clamping block (10). The working groove is fixed as a whole on the xyz three-axis machining platform (23). The working groove contains a liquid confinement medium (14) and a liquid absorption medium (24). The density of the liquid absorption medium (24) is greater than that of the liquid confinement medium (14), and the two are immiscible. An absorption medium conveying system is installed on the wall of the working groove.

2. The laser shock forming apparatus with adjustable absorption layer according to claim 1, characterized in that, The magnetic field force application system includes a circuit system consisting of a controllable DC power supply (1), a commutator (2) and a coil (5), with the coil (5) located above the annular magnet (8).

3. The laser shock forming apparatus with adjustable absorption layer according to claim 2, characterized in that, The absorption medium conveying system includes a flow valve (15), a first liquid storage tank (19), a hydraulic pump (25), a second liquid storage tank (28), and a safety valve (27) connected in sequence. The flow valve (15) and the safety valve (27) are both connected to the working tank through pipelines.

4. The laser shock forming apparatus with adjustable absorption layer according to claim 3, characterized in that, The working tank is also equipped with an ultrasonic vibrator (13), a temperature controller (17) and a pressure sensor probe (21). Outside the working tank, a first three-dimensional information collector (18) and a second three-dimensional information collector (16) are installed. The first three-dimensional information collector (18) is angled to the processing surface of the workpiece (22) to be processed, and the second three-dimensional information collector (16) is flush with the upper surface of the workpiece (22) to be processed.

5. The laser shock forming apparatus with adjustable absorption layer according to claim 4, characterized in that, The safety valve (27) is connected to the computer (6) via the safety valve threshold controller (29), the ultrasonic vibrator (13) is connected to the computer (6) via the ultrasonic controller (12), the xyz three-axis machining platform (23) is connected to the computer (6) via the motion controller (26), the pressure sensor probe (21) is connected to the computer (6) via the pressure sensor (20), and the temperature controller (17), the flow valve (15), the hydraulic pump (25), the controllable DC power supply (1), the commutator (2), and the nanosecond laser (3) are all connected to the computer (6).

6. The laser shock forming apparatus with adjustable absorption layer according to claim 5, characterized in that, The nanosecond laser (3) uses a Gaussian spot with a diameter of 5-8 mm and a laser energy of 50-100 J. The flow rate of the flow valve (15) is 5-20 cm. 3 / min.

7. A method for laser shock forming using the laser shock forming apparatus as described in claim 5, characterized in that, Includes the following steps: S1: Inject an appropriate amount of liquid absorption medium (24) and liquid constraint medium (14) into the working tank, and place the workpiece (22) in it. Place the rectangular pressure plate with the ring magnet (8) on the liquid constraint medium (14). S2: Open the flow valve (15), safety valve (27) and the second three-dimensional information acquisition device (16), and start the safety valve threshold controller (29) to adjust the threshold of the safety valve (27) so that the liquid interface is slightly higher than the upper surface of the workpiece (22) to be processed; S3: Adjust the voltage of the controllable DC power supply (1) and the position of the commutator (2), and apply pressure to the liquid confinement medium (14) by changing the force exerted on the ring magnet (8) by the magnetic field generated by the coil (5), thereby adjusting the liquid height of the liquid absorption medium (24); S4: Start the ultrasonic vibrator (13), temperature controller (17), pressure sensor probe (21), first three-dimensional information acquisition device (18), workpiece to be processed (22), xyz three-axis machining platform (23) and nanosecond laser (3) to process the workpiece (22). During the interval between two impacts, it is necessary to ensure that the first three-dimensional information acquisition device (18) observes no bubbles above the workpiece to be processed (22) and that the pressure sensor (20) does not fluctuate significantly.

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