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Laser shock peening method for improving intensity of laser induced shock wave by adopting time sequence double laser pulse

A technology of laser shock strengthening and laser pulse, applied in the field of improving shock wave intensity and laser shock strengthening, can solve the problems of insufficient utilization of laser energy, affecting shock wave intensity, etc., to achieve the effect of increasing shock wave intensity, enhancing shock wave intensity, and improving production efficiency

Active Publication Date: 2019-09-06
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the existing laser shock peening system generally has insufficient laser energy utilization and affects the shock wave intensity, and provides a laser shock peening method that uses time-sequential double laser pulses to increase the intensity of laser-induced shock waves

Method used

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  • Laser shock peening method for improving intensity of laser induced shock wave by adopting time sequence double laser pulse
  • Laser shock peening method for improving intensity of laser induced shock wave by adopting time sequence double laser pulse
  • Laser shock peening method for improving intensity of laser induced shock wave by adopting time sequence double laser pulse

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Effect test

Embodiment 1

[0026] Embodiment 1: Laser pulse A and laser pulse B are split from the original single laser pulse. For the implementation device, see Figure 6 shown. Figure 1 (a), (b) is the original single laser pulse time waveform and laser spot of the laser used in the verification experiment supporting the present invention. The laser wavelength is 1064nm, the pulse width at half maximum is 12ns, the original spot diameter is 12mm, the total pulse energy is 680±10mJ, the laser spot irradiated to the surface of the workpiece is 1.2mm through lens convergence, and the laser power density is about 5GW / cm 2 .

[0027] Based on the principle of laser-induced plasma detonation waves, the present invention utilizes the changing law of laser absorption characteristics of plasma during ignition and diffusion, and proposes a method of "splitting a single laser pulse and constructing time-sequential double pulses" to successively impact the workpiece, To achieve the purpose of increasing the sh...

Embodiment 2

[0036] Embodiment two: see Figure 7 As shown, laser pulse A and laser pulse B are output by two independent lasers. The specific process is as follows: two independent lasers are used to output two independent laser pulses that are relatively delayed under the control of a delay trigger: laser pulse A, laser pulse b. The delay trigger is implemented by a digital signal generator. After setting the delay amount, two independent pulse lasers are triggered successively to obtain two laser pulses in sequence.

[0037] Others are the same as in Embodiment 1.

Embodiment 3

[0038] Embodiment three: see Figure 8 As shown, the laser pulse train impact strengthening scheme extended from the basic idea and principle of the present invention, such as Figure 8 As shown, according to the needs of the actual process, constructing a time-sequential laser pulse train of more than two pulses and sequentially irradiating and impacting the surface of the workpiece can prolong the duration of the shock wave, increase the impulse, and increase the depth of the residual compressive stress of the workpiece. This is of great significance to laser shock peening engineering and technology. In the specific implementation process, the sub-pulse laser energy size and the time interval between sub-pulse can be set according to the control principle of the plasma electron density described in the present invention, so as to improve the laser energy utilization rate and prolong the duration of the shock wave. Effect.

[0039] The number of split single pulses is set a...

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Abstract

The invention discloses a laser shock peening method for improving the intensity of a laser induced shock wave by adopting a time sequence double laser pulse, and belongs to the field of laser processing. The laser shock peening method aims at solving the problem that existing laser shock peening systems are generally insufficient in laser energy utilization so as to affect the intensity of shockwaves. The method comprises the step that a laser pulse A and a laser pulse B sequentially irradiate and shock the same position of a workpiece surface in a relative delay mode. The specific process comprises the following steps that firstly, the pulse A irradiates and shocks the surface of the workpiece to form an initial plasma, when the electron density of the initial plasma is reduced to be below the critical density of forming the plasma shielding effect, the pulse B which reaches in delay irradiates and shocks a target area, and a part of the laser energy of the pulse B reaches the surface of an absorption layer so as to continue to gasify and ionize the material of the workpiece; and the other part of the laser energy of the pulse B is subjected to inverse bremsstrahlung absorptionby the initial plasma formed through the pulse A. Under the conditions that the output capability of a laser device is not increased and the irradiation area of a light spot is not changed, the purpose of improving the intensity of the shock wave is achieved.

Description

technical field [0001] The invention belongs to the field of laser processing, and relates to a laser shock strengthening technology for the surface of metals, ceramics and other materials, and in particular to a method without amplifying the output capability of a laser device (laser pulse energy) and without changing the size of the irradiation spot on the surface of a workpiece. , a technical method to increase the shock wave intensity by constructing time-sequenced double laser pulses to irradiate and impact the workpiece one after another. Background technique [0002] Laser shock strengthening is a new type of material surface strengthening technology. Its principle is: using short pulses (a few nanoseconds to tens of nanoseconds), high peak power density (greater than GW / cm 2 ) laser beam irradiates the surface of a metal or ceramic workpiece, so that the absorbing protective layer coated on the surface of the workpiece absorbs the laser energy and undergoes explosive...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D10/00
CPCC21D10/005
Inventor 朱成禹远航周罗贤丁奇侃孙鑫常平
Owner HARBIN INST OF TECH
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