CN103526145A - High-quality laser modification life-prolonging method based on laser pulse width modulation - Google Patents
High-quality laser modification life-prolonging method based on laser pulse width modulation Download PDFInfo
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- CN103526145A CN103526145A CN201310469762.1A CN201310469762A CN103526145A CN 103526145 A CN103526145 A CN 103526145A CN 201310469762 A CN201310469762 A CN 201310469762A CN 103526145 A CN103526145 A CN 103526145A
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Abstract
The invention relates to a modification life-prolonging new method based on laser pulse width modulation, and the method is characterized in that: by changing relative delay among three incident lights, a pulse width of a backward wave is modulated; the pulse width of the backward wave is modulated by a double grating linear frequency-modulation pulse amplification method, and a pulse laser with an optimal laser power and power density is obtained by employing a pulse width modulation technology. A high-amplitude shock wave generated by laser shock allows a material to generate elastic plastic deformation, and allows dense dislocation, vacancies and vacancy clusters to be formed on the metal surface. These effects can change the microstructure and mechanical properties of a laser shocked metal, and thus high-quality modification life prolonging of the material surface is realized by the laser.
Description
Technical field
The present invention relates to the laser surface modification technology of lengthening the life, refer in particular to a kind of nanosecond laser alloy material based on laser pulse width modulation and carry out the novel method that modification is lengthened the life, the surface laser modification that is particularly useful for aluminium alloy, titanium alloy and nickel-bass alloy material with lengthen the life.
Background technology
The current laser modified apparatus expensive of lengthening the life, production efficiency is lower, causes use cost higher, can only be confined to use in aircraft industry that technology content is higher, in the general industries such as automobile making, mechanical workout, cannot apply.Major cause is that high energy pulse laser cost is high; And because manufacturing process is complicated, to adopt large-sized operation material in addition, high-power pumping lamp, high-precision plated film lens, causes laser modified lengthening the life to process the laser apparatus costliness of use, and the laser modified efficiency of processing of lengthening the life has much room for improvement; At present domestic laser modified lengthening the life processed laser apparatus used ability impact in about tens seconds once, and foreign applications is in the advanced laser apparatus repetition rate of producing also only in 1Hz left and right, and production efficiency is not high.This just needs the high repetition laser of Development of Novel, and makes it under prerequisite of energy requirement, realize grating and impact meeting, and so once can impact several even tens hot spots, greatly enhances productivity.
Adopt the pulse of novel method modulated laser, obtain the laser modified optimal laser power of lengthening the life of material surface (10-100W), reach high-quality laser selective modification and lengthen the life and just can solve above deficiency.The present invention adopts special amplification technique, with double grating chirp amplification method, carrys out adjusting pulsewidth, reaches the object of optimizing lasing effect.
Summary of the invention
The object of the invention is to overcome the current laser modified apparatus expensive of lengthening the life, the defect that production efficiency is lower and laser device reliability is not high, provides a kind of laser modified novel method of lengthening the life of high quality based on laser pulse width modulation.
Principle of the present invention is: the pulse width that adopts PWM modulation nanosecond laser retonation wave, by regulating the amplitude of ultrashort subpulse to obtain suitable laser pulse width, to obtain, material surface is carried out to best laser power (10-100W) and the power density that modification is lengthened the life, and then the modification that obtains changing the instantaneous local characteristics of metal and the phase transition process novel method of lengthening the life.
The technical scheme that the present invention takes is: a kind of laser modified life-prolonging method of high quality based on laser pulse width modulation, comprises following steps:
A is by changing the relative retardation between three beams incident light, the pulse width of modulation retonation wave, concrete grammar is: by the output Q-switched pulse of Nd:YAG laser apparatus, described Q impulse is obtained to a pulse that approaches rectangle by electric light wave absorption switch, after the described pulse that approaches rectangle is amplified by one-level Nd:YAG amplifier, energy is amplified, and be orthogonal polarized light, described orthogonal polarized light is through 45 ° of total reflective mirrors, condenser lens and beam splitter, orthogonal polarized light is divided into light beam L1 and light beam L2, described light beam L1 is divided into again light beam L3 and light beam L4 through beam splitter, described light beam L2 is divided into again light beam L5 and light beam L6 through beam splitter, described light beam L4 arrives PIN, described light beam L6 arrives high current pipe, for surveying the pulse waveform of incident wave and retonation wave, described light beam L3 and described light beam L5 enter mixing medium CS
2, the another light beam L7 through total reflective mirror 13 also enters mixing medium CS simultaneously
2, optical time delay device carries out relative time delay to three-beam, so that three-beam is overlapping in medium, and produces retonation wave signal.
The retonation wave that B is shortened the pulsewidth obtaining in steps A is through double grating chirp amplifying method modulated laser pulsewidth, detailed process is: first the retonation wave that the pulsewidth in steps A is shortened stretches by double grating pulse stretcher, with the pulse laser that obtains stretching; After this stretching pulse laser amplifies by pulse amplifier paired pulses again, the stretching pulse laser being amplified; The stretching pulse laser of finally this amplification carries out suitable compression by double grating pulse shortener paired pulses, with the short-pulse laser being amplified.
C utilizes the short-pulse laser of the amplification obtaining in step B to carry out the laser modified operation of lengthening the life to the surface of material.
In aforesaid method, described light beam L4 arrives after PIN, described light beam L6 arrive high current pipe and is connected with indicating meter respectively, and described indicating meter is used for its waveform to show.
In aforesaid method, when the pulse of described light beam L3, described light beam L5 and described light beam L7 is strict Gauss pulse, the half-width of described retonation wave is than the pulse width of original incident wave
doubly, irrelevant with time of lag.
In aforesaid method, when the pulse of described light beam L3, described light beam L5 and described light beam L7 is square topped pulse, while not postponing, pulsewidth is constant; The incident pulse that while having delay, the pulsewidth of retonation wave equals described light beam L3, described light beam L5 and described light beam L7 is at described mixing medium CS
2in overlapping time.
Advantage of the present invention is: processing method is simple, and PWM technology is all digital form from treater to controlled system signal, without carrying out digital-to-analog conversion, the resistivity of noise is strengthened, and cost is low; Adopt pulse modulation technology can obtain the pulse laser of optimal laser power and power density.The high-amplitude shockwave that laser-impact produces, makes the distortion of material generation resilient plastic, and forms intensive dislocation, room and vacancy cluster at metal surface.These effects can change microstructure and the mechanical property of laser-impact metal, thereby realize laser, the high quality modification of material surface are lengthened the life.
Accompanying drawing explanation
Fig. 1 Technology Roadmap of the present invention.
Fig. 2 nanosecond retonation wave pulse width modulation apparatus figure.
Fig. 3 double grating chirp amplifying method modulation pulsewidth schema.
The schematic diagram that in Fig. 4 the present invention, retonation wave pulsewidth shortens.
The laser pulse width schematic diagram of modulating through double grating chirp amplifying method in Fig. 5 the present invention
Fig. 6 Fatigue Life for Aluminum Alloy contrast schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, the technical scheme of this law is described in detail.1. first the Q impulse of Nd:YAG laser apparatus 1 is shortened to modulation by Fig. 1 device pulsewidth.Detailed process is as follows: Q impulse is by electric light wave absorption switch 2, and before and after obtaining, edge is less than 1ns, width is about the pulse that 13ns approaches rectangle; Then after amplifying by one-level Nd:YAG amplifier 3, the about 3mJ of energy, and be orthogonal polarized light; This light beam is through 45 ° of total reflective mirrors 4, after condenser lens 5, arrive beam splitter 7, and light beam is divided into two bundle L1 and light beam L2, light beam L1 is divided into again light beam L3 and light beam L4 through beam splitter 6, described light beam L2 through beam splitter 8 be divided into again light beam L5 and light beam L6(wherein the reflectivity of 6,7,8 pairs of 1.06um laser of beam splitter be respectively 43%, 50%, 95%.）。Light beam L4 and light beam L6 arrive respectively PIN 9 and high current pipe 11, for surveying the pulse waveform of incident wave and retonation wave, and on indicating meter 10, demonstrate the pulse waveform of retonation wave.Light beam L3 and light beam L5 enter mixing medium CS
212, under the condition lower than the laser coherence time to the time delay of light beam L3, described light beam L3 and described light beam L5 are at described mixing medium CS
2in 12, produce body grating, obtain the signal of retonation wave; Light beam L7 through total reflective mirror 13 also enters into described mixing medium CS simultaneously
2in 12, described light beam L3, described light beam L5 and described light beam L7 are at described mixing medium CS
2in 12, carry out overlappingly, utilize optical time delay device to carry out relative time delay to three-beam, to modulate the pulsewidth of retonation wave simultaneously.
Along with the increase of three-beam relative retardation, the pulsewidth of retonation wave narrows down gradually, and when time delay is 9ns, the pulsewidth of retonation wave has been shortened 3ns left and right.As shown in Figure 4, shown the schematic diagram that retonation wave pulsewidth shortens.(for different materials, the optimal laser power that laser is lengthened the life to its modification is different with power density, so the pulsewidth of the retonation wave that will modulate is also different).What deserves to be explained is, when the pulse of described light beam L3, described light beam L5 and described light beam L7 is strict Gauss pulse, the half-width of described retonation wave is than the pulse width of original incident wave
doubly, irrelevant with time of lag.When the pulse of described light beam L3, described light beam L5 and described light beam L7 is square topped pulse, while not postponing, pulsewidth is constant; The incident pulse that while having delay, the pulsewidth of retonation wave equals described light beam L3, described light beam L5 and described light beam L7 is at described mixing medium CS
2(12) overlapping time in.When pulse waveform that the pulse of described light beam L3, described light beam L5 and described light beam L7 is other, the effect of described backward pulse compression is between above-mentioned two situations.
2. the retonation wave pulsewidth obtaining being shortened is by the flow process of Fig. 3, as follows: the short-pulse laser of stretching pulse laser → double grating pulse shortener → amplification of double grating pulse stretcher → stretching pulse laser → pulse amplifier → amplification, that is: first the retonation wave of compression pulse width is stretched by double grating pulse stretcher, with the pulse laser that obtains stretching; After this stretching pulse laser amplifies by pulse amplifier paired pulses again, the stretching pulse laser being amplified; The stretching pulse laser of finally this amplification carries out suitable compression by double grating pulse shortener paired pulses, with the short-pulse laser being amplified.The laser obtaining by above step is to meet optimal laser power that material surface modifying is lengthened the life and the pulse laser of power density, thereby can realize efficient, high-quality laser selective modification, lengthens the life (as shown in Figure 5).
Utilize the high quality nanosecond laser obtaining in the present invention to carry out modification to aluminum alloy material surface and lengthen the life, and obtain its fatigue property result, as shown in Figure 6.Can obviously see, utilize short-pulse laser that this programme obtains to carry out modification to aluminum alloy materials and lengthen the life, its fatigue lifetime is more much longer than the fatigue lifetime of common laser.
Claims (5)
1. the laser modified life-prolonging method of high quality of modulating based on laser pulse width, comprises following steps:
A is by changing the relative retardation between three beams incident light, the pulse width of modulation retonation wave, concrete grammar is: by the output Q-switched pulse of Nd:YAG laser apparatus (1), described Q impulse is obtained to a pulse that approaches rectangle by electric light wave absorption switch (2), after the described pulse that approaches rectangle is amplified by one-level Nd:YAG amplifier (3), energy is amplified, and be orthogonal polarized light, described orthogonal polarized light is through 45 ° of total reflective mirrors (4), condenser lens (5) and beam splitter (7), orthogonal polarized light is divided into light beam L1 and light beam L2, described light beam L1 is divided into again light beam L3 and light beam L4 through beam splitter (6), described light beam L2 is divided into again light beam L5 and light beam L6 through beam splitter (8), described light beam L4 arrives PIN(9), described light beam L6 arrives high current pipe (11), for surveying the pulse waveform of incident wave and retonation wave, described light beam L3 and described light beam L5 enter mixing medium CS
2(12), the another light beam L7 of process total reflective mirror 13 also enters mixing medium CS simultaneously
2(12), optical time delay device carries out relative time delay to three-beam, so that three-beam is overlapping in medium, and produces retonation wave signal,
?the retonation wave signal that B is shortened the pulsewidth obtaining in steps A is through double grating chirp amplifying method modulated laser pulsewidth, detailed process is: first the retonation wave that the pulsewidth in steps A is shortened stretches by double grating pulse stretcher, with the pulse laser that obtains stretching; After this stretching pulse laser amplifies by pulse amplifier paired pulses again, the stretching pulse laser being amplified; The stretching pulse laser of finally this amplification carries out suitable compression by double grating pulse shortener paired pulses, with the short-pulse laser being amplified;
C utilizes the short-pulse laser of the amplification obtaining in step B to carry out the laser modified operation of lengthening the life to the surface of material.
2. a kind of laser modified life-prolonging method of high quality based on laser pulse width modulation according to claim 1, it is characterized in that, realize the modulation to retonation wave pulsewidth by the relative retardation changing between three beams incident light, described three beams incident light is respectively light beam L3, light beam L5 and light beam L7; Described light beam L4 arrives PIN(9), described light beam L6 is connected with indicating meter (10) respectively after arriving high current pipe (11), on described indicating meter 10, be used for its waveform to show.
3. a kind of laser modified life-prolonging method of high quality based on laser pulse width modulation according to claim 2, it is characterized in that, when the pulse of described light beam L3, described light beam L5 and described light beam L7 is strict Gauss pulse, the half-width of described retonation wave is than the pulse width of original incident wave
doubly, irrelevant with time of lag.
4. a kind of laser modified life-prolonging method of high quality based on laser pulse width modulation according to claim 2, is characterized in that, when the pulse of described light beam L3, described light beam L5 and described light beam L7 is square topped pulse, while not postponing, pulsewidth is constant; The incident pulse that while having delay, the pulsewidth of retonation wave equals described light beam L3, described light beam L5 and described light beam L7 is at described mixing medium CS
2(12) overlapping time in.
5. a kind of laser modified life-prolonging method of high quality based on laser pulse width modulation according to claim 1, is characterized in that, adopts double grating chirp amplifying method to carry out adjusting pulsewidth, to obtain the pulse laser of optimal laser power and power density.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111628000A (en) * | 2020-05-06 | 2020-09-04 | 武汉大学 | Method for preparing sub-nanometer channel back electrode field effect transistor by laser shock |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5744781A (en) * | 1995-08-07 | 1998-04-28 | General Electric Company | Method and apparatus for laser shock peening |
| CN1404954A (en) * | 2002-09-25 | 2003-03-26 | 江苏大学 | Flexible lamina for laser impact treatment |
| CN1986841A (en) * | 2006-11-03 | 2007-06-27 | 江苏大学 | Method of raising corrosion resistance of magnesium alloy based on reiforcing laser impact technology |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5744781A (en) * | 1995-08-07 | 1998-04-28 | General Electric Company | Method and apparatus for laser shock peening |
| CN1404954A (en) * | 2002-09-25 | 2003-03-26 | 江苏大学 | Flexible lamina for laser impact treatment |
| CN1986841A (en) * | 2006-11-03 | 2007-06-27 | 江苏大学 | Method of raising corrosion resistance of magnesium alloy based on reiforcing laser impact technology |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111628000A (en) * | 2020-05-06 | 2020-09-04 | 武汉大学 | Method for preparing sub-nanometer channel back electrode field effect transistor by laser shock |
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