JP5159516B2 - Laser irradiation device - Google Patents

Description

  The present invention relates to a laser irradiation apparatus for laser peening, and more particularly to a laser irradiation apparatus capable of performing laser peening processing even for a processing object having a complicated shape.

  In most cases, the damage to the structure starts from the surface, such as the occurrence of corrosion or cracks, and the lifetime of the structure tends to depend on the surface characteristics. For this reason, the lifetime of structures has been improved by applying various surface treatment techniques to improve the mechanical or chemical properties of the material surface and improving fatigue strength, corrosion resistance, wear resistance, etc. Attempts to extend are being made.

  Shot peening is a typical surface treatment technique, and can increase the hardness of the member surface layer and introduce compressive residual stress into the surface layer. For this reason, shot peening is often used in industrial fields such as automobiles and aircraft (see, for example, Patent Document 1).

  On the other hand, lasers are capable of precise and high-speed control of energy density and irradiation position, and can perform high-speed processing, super rapid thermal quenching processing, etc. that are difficult with other methods. Applications to material processing are expanding.

  As one of them, a laser shock hardening process in which a surface of a material is irradiated with a pulsed laser beam through a liquid is known. Like shot peening, the hardness of a member surface layer is increased and It is possible to introduce compressive residual stress.

Laser shock hardening treatment has a higher treatment effect than shot peening, non-contact work is possible, there is no reaction force, laser irradiation conditions and parts can be precisely controlled, etc. Excellent advantages that can not be realized with shot peening Development and practical application are underway (see, for example, Patent Document 2 to Patent Document 4 and Non-Patent Document 1).
Japanese Patent Application Laid-Open No. 07-246483 JP 08-111261 A Japanese Patent Laid-Open No. 08-326502 JP 2003-504212 A Shot Peening Technology Association edited by “Metallic Fatigue and Shot Peening”

  In laser peening technology that uses a pulsed laser with a high temporal energy density and improves the mechanical strength of the material by the pressure of the plasma generated when the material surface is irradiated, the spatial energy density of the laser also affects the improvement effect. One of the processing conditions.

Therefore, when the energy (J / pulse) of the irradiated laser pulse is constant, the spatial energy density (J / mm ² ) determined by the area of the image of the laser beam irradiated on the material surface should satisfy the condition. It is necessary to adjust the position of the condenser lens.

When a laser having a wavelength λ and a beam diameter D is condensed by a lens having a focal length f, an ideal focal diameter d of the laser beam is defined by the following diffraction limit equation.
[Equation 1]
d = 2.44 × λ × f / D

  The actual focal diameter becomes larger than the diffraction limit due to various aberrations such as the beam quality of the laser beam when using an actual laser oscillator and the spherical aberration of the lens used. If these are taken into consideration, the area of the image projected on the material surface can be determined from the optical element such as a lens and its arrangement, the refractive index of the transmission space, and the relative distance between the lens and the material surface to be irradiated. After the laser beam is condensed to the minimum diameter, it is enlarged at the same angle as the condensing angle, so that an image of a certain projection area exists before and after the position having the minimum diameter.

  On the other hand, when the light is condensed and the energy density is increased, the probability of occurrence of nonlinear energy loss (breakdown) is increased accordingly. In laser peening in which the pulse energy of the irradiated laser is large and the laser is irradiated in water, breakdown is more likely to occur than in the atmosphere due to the presence of water molecules even if the optical path is kept clean.

For this reason, in laser peening, the image area is limited by setting an upper limit area that is greater than or equal to the energy density necessary to obtain the effect of laser peening and a lower limit area that is greater than or equal to the energy density at which breakdown occurs as processing conditions. The laser peening apparatus must be arranged with the focal position adjusted so that the image area on the surface of the target material satisfies this condition. The focal position where the laser image is the upper limit area and the width of the focal position where the lower limit area is related to the accuracy of equipment installation required for processing, which complicates the design of the irradiation device and the device operation control method. Also, there is a restriction on the shape to be processed.

  The present invention has been made for the purpose of solving these problems associated with the prior art, and has a wide range in the direction of the laser optical axis that forms an image area capable of improving the mechanical strength of the surface of the material to be processed. An object is to provide a laser irradiation apparatus.

In the present invention, pulsed laser light is condensed so that the spatial energy density is high, and the solid material is subjected to the pressure of plasma generated by irradiating the solid material whose surface is in contact with the liquid. A laser irradiation apparatus for improving the mechanical strength of the laser beam, wherein a laser light source, a laser light transmission means for transmitting laser light emitted from the laser light source, and an irradiation position of the laser light on the solid material are arbitrarily moved An irradiation position moving means; a condensing means for condensing the irradiated laser light; and a projection area adjusting means for arbitrarily adjusting a laser projection area when the laser light is projected onto the surface of the solid material. A first optical element configured to refract, diffract, or reflect the laser beam symmetrically with respect to a plane including an optical axis of the laser beam and a first axis perpendicular to the optical axis. A second optical element that refracts, diffracts, or reflects the laser beam symmetrically with respect to a plane that is perpendicular to the optical axis of the laser beam and includes a second axis different from the first axis. And a plurality of surfaces whose surfaces are discontinuously connected to each other as a region for spatially dividing the laser light by at least one of the first optical element and the second optical element. Each of the surfaces has a structure in which the divided laser light is condensed by refraction, diffraction or reflection, and the projection area adjusting means includes the first optical element and the second optical element. The angle formed between the first axis and the second axis on the projection plane perpendicular to the optical axis is changed by rotating at least one of the optical elements about the optical axis. Rotating mechanism To provide over The irradiation apparatus.

According to the present invention, a laser irradiating apparatus for laser peening is provided that expands the processable range on the optical axis of laser light, which is an energy density range necessary for suppressing breakdown and obtaining the effect of laser peening. be able to. As a result, control for focus adjustment can be simplified, and laser peening processing can be performed on a processing object having a complicated shape.

  Hereinafter, embodiments of a laser irradiation apparatus according to the present invention will be described with reference to the drawings.

First Embodiment (FIGS. 1 to 6)
FIG. 1 is an overall configuration diagram showing a part of a laser irradiation apparatus A according to the present embodiment as a cross section. As shown in FIG. 1, the laser irradiation apparatus A is roughly divided into a laser oscillator 1 as a laser light source that oscillates a laser beam L downward, and a laser beam L provided at the lower end of the laser oscillator 1 for controlling the laser beam L. A beam control unit 2, a light guide tube 3 for guiding a laser beam as laser light transmission means extending downward from the beam control unit 2 and having its lower end bent in a substantially horizontal direction, and the light guide tube 3 The water tank 4 which covers the lower end part of this and accommodates a liquid, for example, water w, and the irradiation positioning device 5 provided in a substantially parallel arrangement to the side of the light guide tube 3 are provided.

  The beam control unit 2 includes an output adjustment device 6 that adjusts the output of the laser beam L oscillated from the laser oscillator 1. The output adjusting device 6 includes a partial reflection mirror 7 that extracts a part of the laser beam L as a sampling beam SB, a power meter 8 that detects the output of the extracted sampling beam SB, and a lower part from which the laser beam L is emitted. And a shutter 9 that opens and closes.

  A reflection mirror 10 inclined by 45 ° with respect to the vertical line is provided at the lower portion of the light guide tube 3. After the laser beam L oscillated downward by the reflection mirror 10 is reflected in the horizontal direction to form a horizontal beam. The converged laser beam L1 is converged by the polyhedral condensing element 12 in the irradiation head 11 provided at the tip of the light guide tube 3, and the processed laser beam L1 is irradiated to the processing target member 13 which is a solid material. ing.

  Further, the irradiation positioning device 5 includes a horizontal driving mechanism 15 that performs driving for scanning the laser beam L in the horizontal direction (arrow a direction) along the thickness direction of FIG. 1 and a column 14 that rises vertically. A vertical drive mechanism 16 that moves up and down in the vertical direction (arrow b direction), and a focus adjustment mechanism 17 that moves in the horizontal direction (arrow c direction) by the horizontal drive mechanism 15 to adjust the focus of the laser beam L. I have.

  In this way, the irradiation positioning device 5 performs laser irradiation in the horizontal direction (perpendicular to the paper surface) in order to irradiate the laser beam to an arbitrary region of the member 13 to be processed which is installed in the water tank 4 soaked in the water w. A horizontal drive mechanism 15 for scanning the beam L and a vertical drive mechanism 16 for scanning in the vertical direction (upward on the paper surface) are mounted.

Then, to focus adjustment mechanism 17 the laser light L _1, which is condensed has a desired projected area on the surface of the member to be processed 13, adjust the laser projection area when the projection of the laser beam on the surface of the member to be processed 13 It is used as a projection area adjustment means.

  That is, in the present embodiment, a laser oscillator 1 as a laser light source, a light guide tube 3 and a water tank 4 as laser light transmission means for transmitting laser light emitted from the laser light source, and a member to be processed that is a solid material The irradiation positioning device 5 as an irradiation position moving unit that arbitrarily moves the irradiation position of the laser beam with respect to the laser beam 13, the polyhedral condensing element 12 as a condensing unit that condenses the irradiated laser beam, and the laser beam L as a solid An optical element driving mechanism 26 is provided as projection area adjusting means for arbitrarily adjusting the laser projection area when projected onto the surface of the material.

  With the above configuration, the output of the laser beam L emitted from the laser oscillator 1 is adjusted by the output adjusting device 6 in the beam control unit 2. Laser output measurement for output adjustment is performed by sampling a part of the laser beam L (1% or less of the total output) by the partial reflection mirror 7 and making the sampling beam SB enter the power meter 8. .

  Further, by opening the shutter 9 in the beam control unit 2, the laser beam L is transmitted through the light guide tube 3, the direction of the optical axis is changed by the reflection mirror 10 in the light guide tube 3, and the irradiation head 11 Irradiates the member 13 to be processed.

  FIG. 2 is an enlarged cross-sectional view showing the irradiation head 11 shown in FIG. 1 in detail. As shown in FIG. 2, since the irradiation head 11 and a part of the light guide tube 3 are installed in water, the irradiation head 11 and the light guide tube 3 are provided with O-rings to prevent water from entering the inside. A waterproof structure is formed by a gasket, an adhesive, welding, or other means. The light guide tube 3 and the irradiation head 11 are partitioned by a waterproof window 18 so that when either the light guide tube 3 or the irradiation head 11 is submerged, they do not affect each other through the optical path. .

  The laser beam L incident on the irradiation head 11 is condensed by the polyhedral condensing element 12 after the beam diameter is enlarged by the magnifying mirror 19. The magnifying mirror 19 includes a concave mirror 20 and a convex mirror 21 arranged along the optical axis direction of the laser beam L.

  The polyhedral condensing element 12 is fixedly held by the optical element mount 22 and can be moved in the optical axis direction d by the optical element driving mechanism 26. In other words, the optical element driving mechanism 26 includes a motor 23 provided in the irradiation head 11, a ball screw 24 connected to the motor 23, and a linear guide 25 that supports them. Then, by moving the optical element mount 22 in the optical axis direction (arrow d direction) of the laser beam L by the optical element driving mechanism 26, the focal position viewed from the irradiation head 11 can be linearly moved.

  In this way, the laser beam L is condensed through the polyhedral condensing element 12, passes through the outlet-side waterproof window 27, is emitted into the environment of water w, and is irradiated onto the member 13 to be processed shown in FIG. 1. . An injection nozzle 28 projects from the periphery of the outlet side window 27, and a purified water supply tube 29 is connected to a peripheral wall on the base end side of the injection nozzle 28. Then, the water e filtered by a filter (not shown) is supplied from the purified water supply tube 29 to the injection nozzle 28, and due to the effect of the jet 30 after exiting the injection nozzle 28, it is caused by fine particles or bubbles in the optical path. Scattering and absorption are suppressed.

  Next, the configuration and operation of the polyhedral condensing element 12 will be described with reference to FIGS.

  3A is a front view showing the shape of the polyhedral condensing element 12 from a direction orthogonal to the optical axis, and FIG. 3B is a longitudinal sectional view.

  As shown in FIGS. 3A and 3B, the polyhedral condensing element 12 is a polyhedron in which a plurality of hexagonal small condensing regions 31 are gathered, and each small condensing region 31 is a prism. Play a role.

  Note that the plane normal lines of the small condensing region 31 shown in FIG. 3 are formed so that all intersect at one point. For this reason, when the area of the small condensing region 31 is reduced to the limit, the polyhedral condensing element 12 becomes a spherical lens. When there are a plurality of points where the normals intersect or do not intersect, the polyhedral condensing element 12 when the area of the small condensing region 31 is reduced to the limit becomes an aspherical lens, and an optical element having such a shape is used. May be.

4 and 5 are explanatory diagrams showing beam trajectories. As shown in FIG. 4, in the present embodiment, since the laser beam L is clipped by the small light collecting area 31, the laser light L ₁ after condensing, as shown in FIG. 5, becomes the set of split beams L2, The cross-sectional area of the laser beam at the beam waist L3 having the smallest cross-sectional area can be set by the shape of the small condensing region 31.

  FIG. 6 is an explanatory diagram showing a profile of laser light. As shown in FIG. 6, profiles 32 and 33 show the cross-sectional areas of the laser light when the polyhedral condensing element 12 is arranged at the position a and when the spherical lens is arranged at the same position a.

  Assuming that the apparent focal length from the polyhedral condensing element 12 to the position of the beam waist L3, the focal length of the spherical lens is equal to this. Assuming that the cross-sectional area that is the energy density causing breakdown is s1, and the cross-sectional area that is the energy density necessary to obtain the effect of laser peening is s2, the laser beam L in the optical axis direction in the range from s1 to s2 The processable range is L′ 1 for the spherical lens and L′ 2 for the polyhedral condensing element 12. In the polyhedral condensing element 12, since the cross-sectional area of the beam waist L3 does not reach s1, laser peening can be performed after the beam waist L3, and L′ 2 is longer than L′ 1.

  The projected area on the surface of the member to be processed 13 can be controlled by the focus adjustment mechanism 17 or the optical element driving mechanism 26. The processing position and processing area of the surface of the member to be processed 13 can be controlled by the drive mechanism of the irradiation positioning device 5, and the surface shape of the member to be processed 13 is not a plane perpendicular to the optical axis of the laser beam L. Even in the case where it is not a flat surface, the laser peening process can be performed while maintaining a desired laser projection area by operating the irradiation head 11 in accordance with the shape.

  The driving mechanism of the irradiation positioning device 5 shown in FIG. 1 is a three-axis linear movement including the focus adjustment mechanism 17, but in addition to this, by mounting one or a plurality of rotation mechanisms, a wider variety is provided. Processing operation can be realized. As a result, laser peening processing can be performed in a narrow area where there is a concern about interference between the apparatus and the processing target.

  When the water tank 4 is larger than the laser irradiation apparatus of the present embodiment, the laser oscillator 1 and the irradiation positioning apparatus 5 may be installed in the water together with the light guide tube 3 and the irradiation head 11. In this case, the laser oscillator 1, the beam control unit 2, and the irradiation positioning device 5 are also water-tight, and the connecting portions of the laser oscillator 1, the beam control unit 2 and the light guide tube 3 are also water-tight. In this case, by arranging a window similar to the waterproof window 18 in the irradiation head 11 at the connection between the laser oscillator 1, the beam control unit 2, and the light guide tube 3, it is possible to prevent water from adjoining equipment from mutual. it can.

  3 are all flat surfaces, they may be a spherical aggregate.

  In this embodiment, the liquid in which the material to be treated is immersed is water w. However, this liquid is not limited to water, and an aqueous solution, silicon oil, organic liquid, inorganic liquid, liquid metal, or the like is applied. Also good. In this case, the liquid supplied to the spray nozzle 28 is not water but has the same composition as the immersion environment. The liquid pumped from the water tank 4 is filtered and purified by a filter, and is supplied to the injection nozzle 28, whereby the treatment can be performed regardless of the composition of the environmental liquid.

  Further, by enlarging the beam diameter of the magnifying glass 19 and lowering the energy density on the surfaces of the polyhedral condensing element 12 and the outlet side waterproof window 27, there is an effect of suppressing these damages. Further, a diffusing plate, a lens array, a diffractive optical element (DOE), a kaleidoscope, or the like may be used instead of the magnifying glass 19.

  In addition, the laser beam L may be expanded by forming an optical path using a folding mirror instead of the refracting magnifier shown in FIG.

  As described above, in the laser irradiation apparatus according to the present embodiment, the condensing unit that condenses the laser light includes a plurality of discontinuous plural elements for spatially dividing the laser light by at least one of the optical elements. Each region has a region constituted by a combination of surfaces, and each surface is configured such that the divided laser light is condensed by refraction, diffraction or reflection.

According to the above embodiment, the laser irradiating apparatus for laser peening that expands the processable range on the optical axis of the laser beam, which is an energy density range necessary for suppressing the breakdown and obtaining the effect of laser peening, is provided. Can be supplied. As a result, control for focus adjustment can be simplified, and laser peening processing can be performed on a processing object having a complicated shape.

Second Embodiment (FIGS. 7 to 9)
In the present embodiment, a laser irradiation apparatus will be described in which discontinuous surfaces in an optical element are continuous in the circumferential direction and a set of concentric circular surfaces discontinuous in the radial direction.

  FIG. 7 is an explanatory view showing a concentric prism shape according to the second embodiment of the present invention, and FIG. 8 is an explanatory view showing a beam locus of the embodiment shown in FIG. FIG. 9 is an explanatory view showing a beam waist of the embodiment shown in FIG.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals as those in FIGS. 1 to 6, and redundant descriptions are omitted.

  A concentric optical element 36 shown in FIGS. 7A and 7B is used in place of the polyhedral condensing element 12 of FIG. 1, and is a plurality of concentric condensing regions discontinuous in the radial direction and continuous in the circumferential direction. 37. The concentric condensing region 37 has a shape of an inclined surface when two portions of the triangular pyramid are cut out by a plane parallel to the bottom surface, and each plays the role of a prism. If the width cut by the two planes is made as small as possible, the concentric optical element 36 becomes a lens without spherical aberration.

  In the present embodiment configured as described above, as shown in FIG. 7, the laser beam refracted by the concentric condensing region 37 forms a circular image on the optical axis.

  Further, in the present embodiment, as shown in FIG. 8, the respective inclinations are adjusted so that different concentric condensing regions 37 are imaged at the same position.

  For this reason, as shown in FIGS. 8 and 9, a beam waist 38 for synthesizing images of all concentric condensing regions 37 is provided. The cross-sectional area of the laser beam at the position of the beam waist 38 can be set by the width of the concentric condensing region 37. The cross-sectional area of the laser beam can be represented in FIG. 6 as in the first embodiment.

  Note that the concentric condensing region 37 is not a triangular pyramid, and may have a partial spherical shape when two portions of a sphere are cut by two parallel surfaces.

According to the present embodiment, a laser irradiation apparatus for laser peening is provided that expands the processable range on the optical axis of the laser beam, which is an energy density range required for suppressing the breakdown and obtaining the effect of laser peening. can do. As a result, control for focus adjustment can be simplified, and laser peening processing can be performed on a processing object having a complicated shape.

[Third Embodiment] (FIGS. 10 to 15)
Next, a third embodiment of the laser irradiation apparatus according to the present invention will be described with reference to FIGS. In the following embodiments, a first optical element that refracts, diffracts, or reflects a laser beam symmetrically with respect to a plane including the optical axis of the laser beam and a first axis perpendicular to the optical axis; And a second optical element that refracts, diffracts, or reflects laser light symmetrically with respect to a plane including a second axis perpendicular to the axis, and the laser is configured to collect the laser light by these optical elements An irradiation apparatus will be described. In addition, at least one of the first optical element and the second optical element is a cylindrical lens, and the distance at which the first optical element and the second optical element collect parallel light is different. The laser irradiation apparatus will be described. A laser irradiation apparatus provided with a horizontal drive mechanism for changing the distance between the first optical element and the second optical element will be described. A laser irradiation apparatus provided with a rotation mechanism for rotating at least one of the first optical element and the second optical element around the optical axis will be described.

  FIG. 10 is an enlarged cross-sectional view showing the irradiation head 11 in detail, and FIG. 11 is an explanatory view showing the lens configuration. As shown in FIG. 10, in this embodiment, instead of the polyhedral condensing element 12 in the irradiation head 11 of FIG. 2 shown in the first embodiment, a combined optical element of a vertical cylindrical lens 41 and a horizontal cylindrical lens 42 is used. Use. The vertical cylindrical lens 41 and the horizontal cylindrical lens 42 are both cylindrical lenses, but as shown in FIG. 11, the central axes of the cylinders that form the cylindrical surfaces are configured to be perpendicular to each other.

  The position where the ellipse where the laser beam L is condensed by the vertical cylindrical lens 41 becomes the smallest and the position where the ellipse where the laser beam L is condensed by the horizontal cylindrical lens 42 do not coincide with each other do not coincide. The focal length of the lens and the distance between the lenses are set. Since other configurations are substantially the same as those of the first embodiment, description thereof is omitted.

  12 and 13 show the locus and cross-sectional area of the laser beam L when the curvatures of the vertical cylindrical lens 41 and the horizontal cylindrical lens 42 are equal.

  In the present embodiment configured as described above, as shown in FIG. 12, the vertical cylindrical lens 42 arranged at the position a1 condenses the laser beam L in the beam axis orthogonal direction (x direction) and the x direction. An image is formed in a vertical ellipse at the focal position c.

  Similarly, the horizontal cylindrical lens 42 arranged at the position a2 in FIG. 12 condenses the laser beam L in the beam axis orthogonal direction (y direction) and forms an image in a horizontal ellipse at the y-direction focal position d. From the combination of the two types of cylindrical lenses, as shown in FIG. 13, the spherical lens beam cross-sectional area 102 when a spherical lens having the same curvature as that of the vertical cylindrical lens 41 is disposed at the position a1, as shown in the cross-sectional area 101 of the laser beam. Will always be bigger.

  Even if the cross-sectional area 102 is equal to or smaller than the cross-sectional area 101 that is an energy density causing breakdown, the cross-sectional area 101 does not reach this, and therefore no breakdown occurs. Therefore, the focal points of the vertical cylindrical lens 41 and the horizontal cylindrical lens 42 Laser peening can be performed after positions c and d, and L′ 2 is longer than L′ 1.

  FIG. 14 shows a beam cross-sectional area in the present embodiment. As shown in FIG. 14, when the distance between the vertical cylindrical lens 41 and the horizontal cylindrical lens 42 is increased, the distance between the focal positions c and d is increased. The interval between a1 and a2 can be expanded between c and d to a range where the cross-sectional area 101 becomes an energy density necessary for obtaining the effect of laser peening so as not to be larger than s2.

  FIG. 15 shows an example in which the focal length of the horizontal cylindrical lens 42 is longer than that of the vertical cylindrical lens 41. Here, the focal length of the horizontal cylindrical lens 42 can be increased between c and d within a range in which the cross-sectional area 101 becomes an energy density necessary for obtaining the effect of laser peening so as not to be larger than s2. .

  It is possible to make the focal length of the horizontal cylindrical lens 42 shorter than the focal length of the vertical cylindrical lens 41. These have the effect of changing the center position of the peening processable range, and the same effect as changing the focal length in the spherical lens can be obtained.

  The vertical cylindrical lens 41 and the horizontal cylindrical lens 42 may be replaced with a polyhedral prism in which the cylindrical surface is replaced with the outer surface of a polygonal pyramid.

According to the present embodiment, a laser irradiating apparatus for laser peening that expands the processable range on the optical axis of the laser beam L, which is an energy density range necessary for suppressing breakdown and obtaining the effect of laser peening, is provided. Can be supplied. As a result, control for focus adjustment can be simplified, and laser peening processing can be performed on a processing object having a complicated shape. Further, since the condition of the vertical ellipse and the horizontal ellipse can be selected as the image of the laser beam on the surface of the member to be processed by the focus adjustment mechanism, the laser peening process corresponding to the surface shape of the member to be processed can be performed.

[Fourth Embodiment] (FIGS. 16 and 17)
Next, a fourth embodiment of the laser irradiation apparatus according to the present invention will be described with reference to FIGS. FIG. 16 is a detailed view of the irradiation head, and FIG. 17 is a non-orthogonal cylindrical configuration diagram. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 16, the vertical cylindrical lens 41 and the horizontal cylindrical lens 42 mounted on the irradiation head 11 are each incorporated in a hollow ultrasonic motor 45 that rotates the central axis of the cylinder around the optical axis of the laser beam L, and further optically. The element drive mechanism 26 linearly moves in the optical axis direction of the laser beam L.

In the present embodiment configured as described above, the two hollow ultrasonic motors 45 can operate independently from each other, and therefore, the cylindrical central axes of the vertical cylindrical lens 41 and the horizontal cylindrical lens 42 are formed as shown in FIG. The angle θ can be set to an arbitrary angle. It is assumed that the laser beam L travels from the front to the back with respect to the paper surface. Similarly, since the two optical element driving mechanisms 26 can operate independently from each other, the interval between the two cylindrical lenses can be arbitrarily changed. Unless the angle θ is not 0, the laser light L ₁ has a horizontal oval focus, two focal positions of the vertical ellipse focus.

Since these intervals are determined by the angle θ formed, there is an effect of changing the center position of the peening processable range by controlling the rotation angle of the hollow ultrasonic motor 45, and an effect equivalent to changing the focal length in the spherical lens is obtained. It is done. Further, by controlling the formed angle θ to be 0, the laser light L ₁ is condensed in one direction at one place on the optical axis and is a long ellipse (line shape) that is not condensed in the vertical direction. Get a statue of.

  By changing the lens interval by the optical element driving mechanism 26, the focal length of the combined cylindrical lens can be made variable, and the line angle can also be controlled by the rotation angle control of the hollow ultrasonic motor 45.

According to the present embodiment, a laser irradiation apparatus for laser peening is provided that expands the processable range on the optical axis of the laser beam, which is an energy density range required for suppressing the breakdown and obtaining the effect of laser peening. can do.

  Further, the processable range can be changed without exchanging the lens.

  Furthermore, it is possible to remotely switch the image of the laser beam on the surface of the member 13 to be processed between an elliptical shape and a line-shaped image, and it is possible to remotely select a laser peening process according to the processing conditions.

1 is an overall configuration diagram of a laser irradiation apparatus according to a first embodiment of the present invention. FIG. 2 is an enlarged detailed view showing an irradiation head of the laser irradiation apparatus shown in FIG. 1. (A) is a front view which shows the polyhedral condensing element of FIG. 2, (b) is a longitudinal cross-sectional view of (a). Explanatory drawing which shows the beam locus | trajectory of the polyhedral condensing element shown in FIG. Explanatory drawing which shows the beam waist of the polyhedral condensing element shown in FIG. Explanatory drawing which shows the beam cross-sectional area of the polyhedral condensing element shown in FIG. (A), (b) is explanatory drawing which shows the prism shape by 2nd Embodiment of this invention. Explanatory drawing which shows the beam locus | trajectory of embodiment shown in FIG. Explanatory drawing which shows the beam waist of embodiment shown in FIG. FIG. 5 is a detailed view showing an irradiation head according to a third embodiment of the present invention. Explanatory drawing which shows the lens structure in 3rd Embodiment. Explanatory drawing which shows the beam shape in the said 3rd Embodiment. Explanatory drawing which shows the beam cross-sectional area 1 in the said 3rd Embodiment. Explanatory drawing which shows the beam cross-sectional area 2 in the said 3rd Embodiment. Explanatory drawing which shows the beam cross-sectional area 3 in the said 3rd Embodiment. Detailed view of an irradiation head in a fourth embodiment of the present invention. The non-orthogonal arrangement cylindrical block diagram in the said 4th Embodiment.

Explanation of symbols

1. Laser oscillator, 2. Beam control unit, 3. Light guide tube, 4. Water tank, 5. Irradiation positioning device, 6. Output adjustment device, 7. Partial reflection mirror, 8. Power meter, 9. Shutter, 10. Reflection mirror, 11... Irradiation head, 12 .. Polyhedral condensing element, 13... Member to be processed, 14 .. support, 15 .. horizontal drive mechanism, 16 .. vertical drive mechanism, 17. Magnifying mirror, 20 ... Concave mirror, 21 ... Convex mirror, 22 ... Optical element mount, 23 ... Motor, 24 ... Ball screw, 25 ... Linear guide, 26 ... Optical element driving mechanism, 27 ... Outlet side waterproof window, 28 ... Injection nozzle, DESCRIPTION OF SYMBOLS 30 ... Jet, 31 ... Small condensing area | region, 32, 33 ... Profile, 34 ... Purified water supply tube, 36 ... Concentric optical element, 37 ... Concentric-circle condensing area | region, 38 ... Beam waist, 1 ‥ vertical cylindrical lenses, 42 ‥ horizontal cylindrical lens, 45 ‥ hollow ultrasonic motor, 45A ‥ laser irradiation device, L ‥ laser beam, _{L 1} ‥ convergent laser beam, w ‥ water, SB ‥ sampling beam.

Claims (2)

The mechanical strength of the solid material is obtained by the pressure of the plasma generated by condensing the pulsed laser beam to a high spatial energy density and irradiating the solid material whose surface is in contact with the liquid. A laser light source, a laser light transmission means for transmitting laser light emitted from the laser light source, and an irradiation position moving means for arbitrarily moving the irradiation position of the laser light on the solid material And condensing means for condensing the irradiated laser light, and a projection area adjusting means for arbitrarily adjusting a laser projection area when the laser light is projected onto the surface of the solid material,
The condensing means includes a first optical element that refracts, diffracts, or reflects laser light symmetrically with respect to a plane including an optical axis of the laser light and a first axis perpendicular to the optical axis;
A second optical element that refracts, diffracts, or reflects the laser beam symmetrically with respect to a plane that is perpendicular to the optical axis of the laser beam and includes a second axis different from the first axis. ,
A combination of a plurality of surfaces whose surfaces are discontinuously connected to each other as a region for spatially dividing the laser light by at least one of the first optical element and the second optical element. Each surface has a structure in which the divided laser light is condensed by refraction, diffraction or reflection,
The projected area adjusting means rotates at least one of the first optical element and the second optical element about an optical axis, thereby causing the first axis and the second axis to be Is a rotation mechanism for changing the angle formed on the projection plane perpendicular to the optical axis. The laser irradiation apparatus according to claim 1, wherein the rotation mechanism is a motor that rotates the first optical element or the second optical element and a control unit that remotely controls the motor.

Images