Laser beam combining and forming device and method with time-space phase coordinated control

Abstract

The present invention relates to a laser beam combining and forming device and method with coordinated spatiotemporal phase control, which mainly includes a laser spatiotemporal beam combining device, a laser beam splitting device, and a laser shock forming device. The laser spatiotemporal beam combining device includes two nanosecond lasers, three one-way glasses, three reflectors, a transmission device, and a high-reflective material; the laser beam splitting device includes multiple motors, multiple semi-transparent mirrors, and multiple delay devices; the laser shock forming device includes optical glass, a gasket, an x-y-z three-axis processing platform, and a water spray device. The present invention first uses polarization beam combining to combine two pulse lasers, and then multiplies the combined laser to obtain laser energy with a greater energy density; then, the laser beam splitting device can obtain ultra-high repetition rate laser pulses. The shock waves under the ultra-high repetition rate will have mutual influences, providing a new method for laser shock forming.

Description

Technical Field

[0001] The present invention belongs to the field of laser shock forming, and in particular relates to a laser beam combining and forming device and method with coordinated control of time and space phases. Background Art

[0002] With the continuous development and maturity of laser technology, high-power lasers are finding increasingly widespread applications, profoundly impacting the development of multiple industries. High-energy pulsed lasers require a certain repetition rate in many applications. However, simply increasing the repetition rate of high-energy pulsed lasers can produce severe thermal effects, which can affect laser performance and even cause a decrease in output pulse energy or even inoperability.

[0003] Laser shot peening is a new flexible, precision, moldless forming method. It involves sequentially coating the surface of the workpiece with an absorbing layer and a constraining layer. Laser light passes through the constraining layer, irradiating the workpiece perpendicularly. This laser is absorbed by the absorbing layer, which vaporizes, ionizes, explodes, and expands, inducing a high-pressure plasma shock wave on the workpiece surface. The ultrahigh-pressure plasma shock wave is limited in diffusion by the constraining layer, exerting a strong effect on the workpiece surface. Currently, laser shock peening (LSP) mostly uses high-energy nanosecond lasers. According to research, the maximum repetition rate for high-energy LSP is 20 Hz, resulting in relatively low efficiency. Summary of the Invention

[0004] The object of the present invention is to provide a laser beam forming device and method with coordinated control of time and space phases, which is suitable for realizing laser composite impact processing on the surface of a workpiece.

[0005] In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is: a laser beam forming device with coordinated control of time and space phases, including a laser emission system and an xyz three-axis processing platform, on which a target workpiece is installed. The laser beam emitted by the laser emission system passes through multiple semi-transparent mirrors in sequence, and the laser beam reflected from each semi-transparent mirror is respectively delayed by a delay device and then irradiated onto the target workpiece.

[0006] In the above solution, each of the semi-transparent mirrors is fixed on the output shaft of the motor.

[0007] In the above scheme, the laser emission system includes a first nanosecond laser, a second nanosecond laser, one-way glass 1, one-way glass 2, a first reflector, a second reflector, a third reflector and a high-reflective material. The back of the high-reflective material is adhered to one-way glass 3. The laser beam emitted from the one-way glass 3 is transmitted to the semi-transparent mirror. The emission ports of the first nanosecond laser and the second nanosecond laser are arranged vertically. The laser beam emitted by the first nanosecond laser and the laser beam emitted by the second nanosecond laser are polarized and combined through the one-way glass 1 and then re-emitted from the one-way glass 2, the first reflector, the second reflector, the high-reflective material and the third reflector to the one-way glass 2 to form a closed optical path loop.

[0008] In the above solution, a gasket is installed above the target workpiece, and the gasket supports the optical glass.

[0009] In the above solution, a water spraying device is provided near the target workpiece.

[0010] In the above solution, the high reflective material is wound on a conveyor belt.

[0011] In the above solution, the first nanosecond laser, the second nanosecond laser, the conveyor belt, the delay device, the motor, the water spray device, and the xyz three-axis machining platform are all connected to a computer.

[0012] In the above solution, the high-reflective material can be any one of gold foil, silver foil, and copper foil, and the thickness of the high-reflective material is 5-100 μm.

[0013] The present invention also provides a laser beam forming method with coordinated time-space phase control, which is characterized in that it includes the following steps: S1 starts multiple motors to control the semi-transparent mirror to rotate to a suitable position, and adjusts the delay time of multiple delay devices; S2 simultaneously starts the first nanosecond laser, the second nanosecond laser, the conveyor belt and the xyz three-axis processing platform, and the laser beam is cyclically reflected in a closed-loop optical path composed of one-way glass two, the first reflector, the second reflector, the high-reflective material, and the third reflector. When the high-reflective material is vaporized and penetrated, the beam is strengthened to the limit and is then transmitted to the semi-transparent mirror through the one-way glass three. The laser beam reflected from each of the semi-transparent mirrors is respectively delayed by the delay device and then irradiated onto the target workpiece, thereby realizing composite laser impact processing of the target workpiece.

[0014] The beneficial effects of the present invention are as follows: (1) Polarization beam combining is used to superimpose the energies of two lasers. The synthesized laser beam is continuously strengthened through circulation, and a larger laser energy can be obtained. Theoretically, the energy can be increased by up to 1 / (1-a) times (a is the reflectivity of the high-reflectivity material). (2) The high-energy laser beam can be divided into several parts by multiple semi-transparent mirrors, greatly improving the laser repetition frequency. (3) Different light spots are combined into different light spot shapes and energy density distributions. (4) When it is a liquid confinement layer, multiple shock waves inside the target workpiece affect each other within nanoseconds, forming a new impact method and impact effect. (5) When it is a rigid confinement layer, the detonation waves on the surface of the target workpiece affect each other within nanoseconds to increase the impact force, which can form a new impact method. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0016] Figure 2 Schematic diagram of the interaction of shock waves within the workpiece under the liquid confinement layer.

[0017] Figure 3 Schematic diagram of the interaction of shock waves inside the workpiece under the rigid constraint layer.

[0018] Figure 4 Schematic diagram of the effect of multi-spot combined impact.

[0019] In the figure: 1 - First nanosecond laser, 2 - Second nanosecond laser, 3 - One-way glass 1, 4 - One-way glass 2, 5 - Reflector, 5-1 - First reflector, 5-2 - Second reflector, 5-3 - Third reflector, 6 - Conveyor belt, 7 - High-reflective material, 8 - One-way glass 3, 9 - Motor, 10 - Semi-transmissive mirror, 11 - Delay device, 12 - Optical glass, 13 - Target workpiece, 14 - Spacer, 15 - XYZ three-axis machining platform, 16 - Computer, 17 - Water spray device, 18 - First shock wave, 19 - Water, 20 - Second shock wave, 21 - First detonation wave, 22 - Second detonation wave. DETAILED DESCRIPTION

[0020] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0021] The technical solution of the present invention is described in more detail below with reference to the accompanying drawings.

[0022] like Figure 1As shown, the laser beam combining and forming device with coordinated spatiotemporal phase control provided in this embodiment includes a laser spatiotemporal beam combining device, a laser beam splitting device, and a laser shock forming device. The laser spatiotemporal beam combining device includes a first nanosecond laser 1 and a second nanosecond laser 2, one-way glass 1 3 and one-way glass 2 4, a first reflector 5-1, a second reflector 5-2, a high-reflective material 7 and a third reflector 5-3, a conveyor belt 6, and the high-reflective material 7. The high-reflective material 7 is closely attached to the one-way glass 3 8. The conveyor belt 6 can transport the high-reflective material 7 and move intermittently. The first nanosecond laser 1 is stationary when emitting light and moves otherwise. The laser beam splitting device includes multiple motors 9, multiple semi-transparent mirrors 10, and multiple delay devices 11. The multiple motors 9 control the rotation of the multiple semi-transparent mirrors 10 to change the direction of the laser. The multiple delay devices 11 can change the time it takes for the light beam to reach the target workpiece 13. The laser shock forming device includes the target workpiece 13 and an xyz three-axis machining platform 15. When a liquid constrained layer is used, a water spray device 17 is installed near the target workpiece 13. When a rigid constrained layer is used, a gasket 14 is installed on the target workpiece 13, and an optical glass 12 is installed above the target workpiece 13 through the gasket 14. The first nanosecond laser 1, the second nanosecond laser 2, the conveyor belt 6, the delay device 11, the motor 9, the water spray device 17, and the xyz three-axis machining platform 15 are all connected to a computer 16.

[0023] The laser energy of the first and second nanosecond lasers 1 and 2 is Q. After polarization beam combining through one-way glass 1 (3), the laser energy is 2Q. The laser energy is then re-emitted back to one-way glass 2 (4), passing through the first reflector 5-1, the second reflector 5-2, the high-reflective material 7, and the third reflector 5-3, further enhancing the laser energy. The high-reflective material 7 can be made of smooth gold, silver, or copper foil, and has a thickness of 5-100 μm. Assuming the reflectivity of the high-reflective material 7 to the laser is fixed at a, and the laser propagation paths continuously overlap, the combined laser energy can theoretically be amplified by a factor of up to 1 / (1-a).

[0024] The laser beam combining and forming method with coordinated time-space phase control provided in this embodiment includes the following steps: S1 starts multiple motors 9 to control the semi-transparent mirror 10 to rotate to a suitable position, and adjusts the delay time of multiple delay devices 11; S2 simultaneously starts the first nanosecond laser 1, the second nanosecond laser 2, the conveyor belt 6 and the xyz three-axis processing platform 15, and the laser beam is cyclically reflected in a closed-loop optical path composed of the one-way glass 2 4, the first reflector 5-1, the second reflector 5-2, the high-reflection material 7, and the third reflector 5-3. When the high-reflection material 7 is vaporized and penetrated, the beam is strengthened to the limit and then transmitted to the semi-transparent mirror 10 through the one-way glass 3 8. The laser beam reflected from each of the semi-transparent mirrors 10 is respectively delayed by the delay device 11 and then irradiated onto the target workpiece 13, thereby realizing composite laser impact processing of the target workpiece 13.

[0025] When multiple semi-transparent mirrors 10 and multiple delay devices 11 control multiple laser beams to irradiate the surface of the target workpiece 13 at the same time, the shape and energy distribution of the laser spot 23 can be freely combined. Figure 2 As shown, when the multiple semi-transparent mirrors 10 and the multiple delay devices 11 control the multiple laser beams to arrive at the surface of the target workpiece 13 in sequence, and the water 19 is used as a confinement layer, ultra-high repetition rate laser shock can be achieved. The first shock wave 18 and the second shock wave 20 generated inside the target workpiece 13 affect each other, and a new shock method emerges. Figure 3 As shown, when the multiple semi-transparent mirrors 10 and the multiple delay devices 11 control the multiple laser beams to arrive at the surface of the target workpiece 13 in sequence, and the optical glass 12 is used as a constraint layer, the first detonation wave 21 and the second detonation wave 22 on the surface of the target workpiece 13 can be mutually affected, resulting in a new impact method. The shape of the spot 23 is as follows Figure 4 shown.

Claims

1. A laser beam forming device with coordinated time-space phase control, comprising a laser emission system and an xyz three-axis processing platform (15), wherein a target workpiece (13) is mounted on the xyz three-axis processing platform (15), characterized in that: The laser beam emitted by the laser emission system passes through a plurality of semi-transparent mirrors (10) in sequence, and the laser beam reflected from each semi-transparent mirror (10) is respectively delayed by a delay device (11) and irradiated onto the target workpiece (13). The laser emission system comprises a first nanosecond laser (1), a second nanosecond laser (2), a one-way glass 1 (3), a one-way glass 2 (4), a first reflector (5-1), a second reflector (5-2), a third reflector (5-3) and a high-reflection material (7). The back of the high-reflection material (7) is bonded with a one-way glass 3 (8). The laser beam emitted from the one-way glass 3 (8) is transmitted to the target workpiece (13). To the semi-transparent mirror (10), the emission ports of the first nanosecond laser (1) and the second nanosecond laser (2) are arranged vertically, and the laser beam emitted by the first nanosecond laser (1) and the laser beam emitted by the second nanosecond laser (2) are polarized and combined through the one-way glass (3) and then re-emitted from the one-way glass (4), the first reflector (5-1), the second reflector (5-2), the high-reflection material (7) and the third reflector (5-3) to the one-way glass (4) to form a closed optical path. When the high-reflection material (7) is vaporized and penetrated, the light beam is strengthened to a limit and then transmitted to the semi-transparent mirror (10) through the one-way glass (8).

2. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 1, characterized in that: Each of the semi-transmissive mirrors (10) is respectively fixed on an output shaft of the motor (9).

3. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 2, characterized in that: A gasket (14) is installed above the target workpiece (13), and an optical glass (12) is supported on the gasket (14).

4. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 3, characterized in that: A water spray device (17) is provided in the vicinity of the target workpiece (13).

5. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 4, characterized in that: The high reflective material (7) is wound on the conveyor belt (6).

6. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 5, characterized in that: The first nanosecond laser (1), the second nanosecond laser (2), the conveyor belt (6), the delay device (11), the motor (9), the water spray device (17), and the xyz three-axis processing platform (15) are all connected to a computer (16).

7. The laser beam combining and shaping device with spatiotemporal phase coordinated control according to claim 5, characterized in that: The high-reflective material (7) is any one of gold foil, silver foil, and copper foil, and the thickness of the high-reflective material (7) is 5-100 μm.

8. A laser beam combining method for performing spatiotemporal phase coordinated control using the device according to claim 1, characterized in that: The following steps are involved: S1 starts multiple motors (9) to control the semi-transparent mirror (10) to rotate to a suitable position, and adjusts the delay time of multiple delay devices (11); S2 simultaneously starts the first nanosecond laser (1), the second nanosecond laser (2), the conveyor belt (6) and the xyz three-axis processing platform (15). The laser beam is circularly reflected in a closed-loop optical path composed of the one-way glass two (4), the first reflector (5-1), the second reflector (5-2), the high-reflection material (7) and the third reflector (5-3). When the high-reflection material (7) is vaporized and penetrated, the beam is strengthened to a limit and then transmitted to the semi-transparent mirror (10) through the one-way glass three (8). The laser beam reflected from each of the semi-transparent mirrors (10) is respectively delayed by the delay device (11) and then irradiated onto the target workpiece (13), thereby realizing the composite laser impact processing of the target workpiece (13).

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