JP2017217658A - Laser processor, laser processing method, optical system and padding processed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processor capable of changing flexibly a light intensity distribution at a processing point by a simple constitution, and controlling easily heat input into a workpiece; and to provide a laser processing method, an optical system and a padding processed product.SOLUTION: A laser processor includes a laser source 12, a condensation part 14 for condensing a light flux L generated from the laser source 12 toward a workpiece W, and a light flux converter having a nonuniform transmissivity to the light flux L condensed by the condensation part 14, and containing an optical element 16 for non-uniformizing a light intensity distribution at a condensation point P.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser processing apparatus, a laser processing method, an optical system, and a built-up product.

  As an apparatus for processing a workpiece, there is a laser processing apparatus. By using a laser processing apparatus, it is possible to perform various processes such as drilling, cutting, welding, quenching, and cladding (building up) on a workpiece such as metal. In addition, various studies have been conducted on the laser beam profile (light intensity distribution, energy density) in the vicinity of the processing point of the laser light source used in the laser processing apparatus and the method of forming the laser light source, depending on the processing content to be applied.

  In other words, in laser processing, the desired beam of the laser light source used for laser processing according to the processing content, workpiece, heat input to the workpiece (amount of heat applied from the outside to the vicinity of the processing point during processing), etc. Since the profiles are different, the beam profile in the vicinity of the processing point of the laser light source, that is, the light intensity distribution is required to be flexibly changed.

  One method for changing the profile of the laser beam is to use a spatial modulator (liquid crystal, optical crystal, micromachine, etc.). In other words, by making the laser beam incident on the spatial modulator and transmitting or reflecting it through the spatial modulator, the transmittance with respect to the laser beam and the phase of the laser beam are controlled, and the intensity distribution at the condensing point can be controlled. It is a method to adjust.

  Further, as a prior art relating to a laser beam profile, a laser processing apparatus disclosed in Patent Document 1 is known. The laser processing apparatus disclosed in Patent Document 1 includes a solid-state laser oscillator that outputs a laser, and an optical system that focuses the laser output from the solid-state laser oscillator and irradiates the workpiece. The solid-state laser oscillator outputs a laser having a shape in which a beam profile in a cross section passing through the center of the laser traveling direction forms a plurality of peaks whose outputs are higher than the center outside the center. The workpiece is irradiated with a laser whose position is shifted from the machining position of the workpiece. In the laser processing apparatus disclosed in Patent Document 1, by having such a configuration, the laser irradiated to the workpiece is distributed with a stronger output on the end side of the region irradiated with the laser. Therefore, a strong laser can be irradiated to the end of the processing region of the workpiece, and processing can be performed with high accuracy.

  On the other hand, as a processing method that takes advantage of the characteristics of laser processing, there is overlaying. The build-up process is a process in which a material different from the base material is melted and solidified in a predetermined portion of the base material to improve the surface strength and wear resistance of the predetermined portion of the base material. In laser processing, a laser light source is used as a heat source in the build-up processing.

  As a document disclosing a laser processing apparatus for build-up processing, a laser processing apparatus disclosed in Patent Document 2 is known. In the laser processing apparatus disclosed in Patent Document 2, while continuously feeding a predetermined amount of copper-based alloy powder while applying rotational feed to the valve seat of the cylinder head, an integrating mirror having a concave cylindrical mirror and a thin flat mirror as a segment Then, a laser beam formed linearly is irradiated from above the copper-based alloy powder to form a build-up layer of the copper-based alloy on the valve seat. In the laser processing apparatus disclosed in Patent Document 2, by having such a configuration, the energy density characteristic of the linear laser beam becomes substantially uniform in the build-up width direction. It is said that it is difficult to cause partial variations in the amount of heat input, and it is possible to form a good build-up layer without partial dilution of the base material particularly in the build-up width direction.

Japanese Patent No. 5595573 Japanese Patent No. 3232940

  However, since the spatial modulator is not generally configured to irradiate a laser beam with a high output (several kW) like the optical output of the laser processing apparatus, a part of the optical output of the laser processing apparatus is spatially modulated. If it hits a mirror (generally made of metal), it may melt.

  On the other hand, in the laser processing apparatus disclosed in Patent Document 1, the light intensity distribution is changed by defocusing the focal point of the laser beam. In such a method, movement in the optical axis direction that changes the light intensity distribution is performed. There is a problem that the range is limited and the variable width of the light intensity distribution is small. Therefore, there is room for improvement in terms of flexible change of the heat input profile.

  Furthermore, the laser processing apparatus disclosed in Patent Document 2 specializes in build-up processing, and intends to make the light intensity distribution uniform by using a special optical system that is a combination of a concave cylindrical mirror and an integrating mirror. However, it does not correspond to a flexible change of the light intensity distribution. Moreover, since the laser processing apparatus disclosed in Patent Document 2 is a reflection type, there is a disadvantage that the apparatus becomes large and the cost is increased accordingly.

  The present invention has been made in order to solve the above-described problems. The light intensity distribution at a processing point can be flexibly changed with a simple configuration, and the heat input to the workpiece can be easily controlled. An object of the present invention is to provide a laser processing apparatus, a laser processing method, an optical system, and a build-up product.

  In order to achieve the above object, a laser processing apparatus according to claim 1 includes a laser light source, a condensing unit that condenses a light beam generated from the laser light source toward a workpiece, and the condensing unit. A light beam conversion unit including an optical element that has a non-uniform transmittance with respect to the condensed light beam and makes the light intensity distribution at the light condensing point non-uniform.

  According to a second aspect of the present invention, in the first aspect of the present invention, the optical element is formed of columnar quartz.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the light intensity distribution has a substantially circular outer shape, and the light intensity is low in the diameter direction of the circular shape. By having a region, the light intensity distribution is made non-uniform.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the light beam conversion unit includes a plurality of the optical elements.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the light generated from the laser light source is interposed between the laser light source and the condensing unit. It further includes a collimating portion for parallel light.

  The invention according to claim 6 is provided with a build-up member supply unit for supplying a build-up member for performing build-up processing in the invention according to any one of claims 1 to 5. The build-up processing unit further includes a build-up processing unit, and the build-up processing unit moves the work piece from the build-up member supply unit while relatively moving the build-up member supply unit, the light flux, and the work piece. The build-up member is supplied on top, and the build-up processing is performed by irradiating the supplied build-up member with the light beam.

  The invention according to claim 7 is the invention according to claim 6, wherein the build-up processing portion performs the build-up processing to form a valve seat of a cylinder head for an internal combustion engine. .

  In order to achieve the above object, an optical system according to claim 8, a light collecting unit that collects a light beam generated from a light source, and a non-uniform transmission with respect to the light beam collected by the light collecting unit. And an optical element that makes the light intensity distribution at the condensing point non-uniform.

  In order to achieve the above object, in the laser processing method according to claim 9, the light beam generated from the laser light source is condensed toward the workpiece by the light collecting unit, and is collected by the light collecting unit. The light intensity distribution at the condensing point is made non-uniform by a light beam conversion unit including an optical element having non-uniform transmittance with respect to the light beam.

  The invention according to claim 10 is the invention according to claim 9, wherein the build-up processing unit includes a build-up member supply unit that supplies a build-up member supply unit for performing build-up processing. The build-up member is supplied onto the workpiece from the build-up member supply unit while relatively moving the member supply unit, the light beam, and the workpiece, and the supplied build-up member The build-up processing is performed by irradiating the light flux.

  In order to achieve the above object, the build-up product according to claim 11 includes a base material made of a first metal, a build-up part formed of the second metal on the base material, and the base material. And an alloy part that melt-joins the base material and the build-up part disposed between the material and the build-up part, and the shape of the joint surface between the base material and the alloy part is a bowl shape A build-up product, wherein the build-up part and the alloy part have a light beam generated from a laser light source generated by a light collecting unit when a build-up member is supplied on the base material. The light intensity distribution at the condensing point is made non-uniform by the light beam conversion unit including an optical element that is condensed toward the light and has a non-uniform transmittance with respect to the light beam collected by the light collecting unit. As a result, the light beam is irradiated on the supplied build-up member, and the build-up processing is performed. And it is formed.

  According to the present invention, a laser processing apparatus, a laser processing method, an optical system capable of flexibly changing a light intensity distribution at a processing point with a simple configuration and easily controlling heat input to a workpiece. In addition, there is an effect that the processed meat product can be provided.

It is a figure which shows an example of the structure of the laser processing apparatus which concerns on 1st Embodiment, the figure which shows an example of an optical element, and the figure which shows an example of a beam profile. It is the graph and photograph which show an example of the light intensity distribution in the processing point of the laser light source concerning a 1st embodiment. It is sectional drawing which shows an example of the state of the hardening process by the laser processing apparatus which concerns on 1st Embodiment, and sectional drawing which shows the state of the hardening process by the laser processing apparatus which concerns on a prior art. It is a figure which shows an example of a structure of the laser processing apparatus which concerns on 2nd Embodiment, and a figure which shows a beam profile. It is a figure which shows an example of a structure of the optical element which concerns on 3rd Embodiment, and a figure which shows a beam profile. It is a figure which shows an example of a structure of the laser processing apparatus which concerns on 4th Embodiment. It is a figure explaining manufacture of the valve seat using the build-up process by the laser processing apparatus which concerns on 4th Embodiment. It is a figure explaining the build-up process part by the laser processing apparatus which concerns on 4th Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
A laser processing apparatus 10 according to the present embodiment will be described with reference to FIGS. As shown in FIGS. 1A and 1C, the laser processing apparatus 10 includes a laser light source 12, a condensing element 14, and an optical element 16 (light beam conversion unit).

  The laser light source 12 is a heat source that supplies heat at the time of processing. In the present embodiment, the laser light source 12 is configured using a semiconductor laser. The laser light source 12 includes a collimator lens (not shown) and outputs parallel light emitted from the semiconductor laser as a light beam L. Further, the semiconductor laser constituting the laser light source 12 may be a single semiconductor laser or a semiconductor laser array in which a plurality of light emitting points are arranged. In the present embodiment, the light beam L is parallel light. However, the present invention is not limited to this. For example, the light beam L condensed to a certain degree toward the processing point P of the workpiece W may be used.

  In the present embodiment, an example in which a semiconductor laser is used as the laser light source 12 will be described as an example. However, the present invention is not limited to this, and an Nd: YAG (neodymium: yttrium, aluminum, garnet) solid state laser, fiber laser, and fiber transmission Other types of laser light sources, such as a type laser (a light source that transmits a solid-state laser output or a semiconductor laser output using an optical fiber), may be used.

  The condensing element 14 is an element that condenses the light beam L toward the processing point P of the workpiece W, and for example, a lens can be used. The lens constituting the condensing element 14 may be a single lens or a plurality of lens groups.

  The optical element 16 according to the present embodiment is an element that has a lens action and changes the beam profile of the laser light source 12 by converting a part of the optical axis of the light beam L. The optical element 16 is disposed, for example, in a processing torch of the laser processing apparatus 10. An optical system 20 according to the present embodiment is configured including the condensing element 14 and the optical element 16. As shown in FIG. 1E, the optical element 16 according to the present embodiment has a cylindrical outer shape as an example, and is formed of a material transparent to the wavelength of the laser light source 12, such as quartz. Yes. That is, the optical element 16 according to the present embodiment is a quartz rod (quartz rod). The processing torch is a head portion that emits laser light, and generally has a shape in which a cylinder and a cone are connected.

  Here, when laser processing is performed by a laser processing apparatus having a high-power (for example, several kW) laser, processing characteristics (processing conditions such as drilling, welding, and quenching) are examined while examining the light intensity distribution at the processing point. Sometimes you want to improve. In general, in order to change the light intensity distribution at the focal point (processing point), it is necessary to prototype various optical systems composed of special lenses and determine the suitability of the optical system while observing the processing state. It was. As a result, the laser processing apparatus according to the prior art requires a great amount of time and cost for trial and error until the optical system is determined.

  Therefore, in the present embodiment, the optical system 20 that can easily change the beam profile is employed. That is, an optical component having a lens effect such as a quartz rod is disposed in the optical path of the light beam L. In this case, due to the lens effect of the quartz rod, the laser light passing through the quartz rod creates a condensing point other than the condensing point before the quartz rod is inserted, and diverges at the original condensing point. In this way, the light intensity distribution at the original condensing point is adjusted by causing a partial loss in the laser light passing through the quartz rod.

  With the above configuration, the laser processing apparatus 10 according to the present embodiment can significantly reduce the time and cost for determining the optical system. Further, by making it possible to easily change the beam profile, in the laser processing apparatus 10 according to the present embodiment, the heat input distribution to the workpiece can be easily adjusted. Hereinafter, the operation of the optical element 16 according to the present embodiment will be described in more detail.

  FIGS. 1B and 1D show a spot S (beam profile or irradiation pattern) formed at a processing point P by the optical system 20. As shown in FIGS. 1B and 1D, the spot S according to the present embodiment has a substantially circular shape as a whole and has a slit portion B extending in the diameter direction. The slit part B is an area where the light intensity is lower than the area around the slit part B. That is, in the laser processing apparatus 10 according to the present embodiment, the spot S is formed into a shape having a non-uniform light intensity distribution in which the light intensity in the center portion is linearly reduced, so that the laser beam is focused on the center portion. It is possible to keep power from concentrating.

  More specifically, as a result of the light beam L being condensed by the light condensing element 14, the light beam L tends to form a condensing point (imaging point) in the vicinity of the processing point P or the processing point P. However, as shown in FIG. 1C, the light beam L that forms a condensing point is refracted outward along the diameter direction of the optical element 16 by the lens action of the optical element 16 and is scattered. Therefore, since a part of the light beam L to be collected does not reach the condensing point, the spot S does not have a uniform light intensity distribution, and has a shape having a slit portion B whose light intensity is reduced in the diameter direction. Become. In other words, the optical element 16 is an element that converts the optical path of the light beam L having a substantially uniform light intensity distribution and two-dimensionally converts the light intensity distribution (makes the light intensity distribution biased).

  In the present embodiment, a description will be given by exemplifying a form in which the spot S has a substantially circular shape. However, the present invention is not limited to this. Good. Further, in the present embodiment, a description is given of an example in which the slit portion B reaches the outer edge of the spot S. However, the present invention is not limited to this, and the slit portion B may be included in the outer shape of the spot S. . Furthermore, in the present embodiment, a description will be given by exemplifying a form in which the slit portion B is arranged at the center portion (the portion corresponding to the diameter) of the spot S. It is good also as a form arrange | positioned in the position where the part biased.

  With reference to FIG. 2, the actual observation result of the spot S of the laser beam in the laser processing apparatus 10 will be described. In FIG. 2, the distance d (see FIG. 1 (a)) between the optical element 16 and the processing point P is used as a parameter.

  In this observation, in the laser processing apparatus 10 shown in FIG. 1A, the focal length f of the light converging element 14 is set to f = 380 mm, and the diameter of the optical element 16 is set to 1 mm. 2A shows the light intensity distribution in the A-A ′ direction shown in FIG. 1B when d = 19 mm, and FIG. 2B shows a photograph of the spot S. 2C shows the light intensity distribution in the AA ′ direction shown in FIG. 1B when d = 64 mm, and FIG. 2D shows a photograph of the spot S. .

  As shown in FIGS. 2A and 2C, the light intensity distribution of the spot S has a shape having a concave portion C near the center corresponding to the slit portion B. 2A and 2C, and FIG. 2B and FIG. 2D, the slit portion B when the distance d is 19 mm has a distance d. The light intensity at the portion of the slit portion B is lower than that at the slit portion B in the case of 64 mm, and the boundary with the region other than the slit portion B becomes clearer. In other words, it can be seen that by increasing the distance d, it is possible to suppress a decrease in light intensity at the slit portion B and to broaden the light intensity distribution. That is, in the present embodiment, as an example, the light intensity distribution of the spot S at the processing point P can be adjusted by adjusting the distance d between the optical element 16 and the processing point P.

  Next, with reference to FIG. 3, a description will be given of trial results when the quenching process is actually performed by the laser processing apparatus 10 according to the present embodiment. FIG. 3A is a cross-sectional view showing the quenched portion 100 when the metal base material 104 is quenched by the laser machining apparatus 10 according to the present embodiment, and FIG. 3B is related to the prior art. It is sectional drawing which shows the hardening part 102 at the time of performing a metal hardening process to the metal base material 104 with a laser processing apparatus. The laser processing apparatus according to the prior art is a laser processing apparatus having a configuration excluding the optical element 16 in FIGS. 1A and 1C, and its beam profile is, for example, near the center in FIG. The shape has no concave portion C.

  As apparent from comparison between FIGS. 3A and 3B, the laser processing apparatus according to the prior art generates an excessively hardened portion (heat input) in the center portion, whereas the present embodiment According to the laser processing apparatus 10 according to the above, it can be seen that quenching can be performed in a shallow and wide area. That is, according to the laser processing apparatus 10 according to the present embodiment, it is possible to set an optimal heat input profile according to the processing purpose and the like.

  As described above in detail, according to the laser processing apparatus, the optical system, and the laser processing method according to the present embodiment, the light intensity distribution at the processing point can be flexibly changed with a simple configuration, and the workpiece There is an effect that heat input to can be easily controlled.

[Second Embodiment]
With reference to FIG. 4, the laser processing apparatus 10a which concerns on this Embodiment is demonstrated. The laser processing apparatus 10a according to the present embodiment is obtained by changing the optical element 16 and the optical system 20 to the optical element 16a and the optical system 20a in the laser processing apparatus 10 described above. Therefore, since the configuration other than the optical element 16a and the optical system 20a is the same as that of the laser processing apparatus 10, the same reference numerals are given to the same configurations, and detailed description thereof is omitted.

  As shown in FIGS. 4A and 4C, the optical element 16a of the laser processing apparatus 10a is a mask formed of a metal plate. As the metal material, a material that exhibits reflection characteristics (partial absorption characteristics) with respect to the wavelength of the laser beam of the laser processing apparatus 10a is selected. Also in the laser processing apparatus 10a, as shown in FIGS. 4B and 4D, the spot S having the slit portion B can be formed. However, in the present embodiment, since the metal generally melts by absorbing a part of the kW class laser beam, the relationship between the wavelength of the laser light source 12 and the reflection (absorption) characteristics of the optical element 16a, etc. It is preferable to fully examine the above.

[Third Embodiment]
With reference to FIG. 5, the laser processing apparatus 10b which concerns on this Embodiment is demonstrated. FIG. 5A is a plan view and a side view of the optical element 16b according to the present embodiment, and FIG. 5B is a view showing a spot S formed by the optical element 16b. The laser processing apparatus 10b is obtained by changing the optical element 16 and the optical system 20 to the optical element 16b and the optical system 20b, respectively, in the laser processing apparatus 10 according to the above embodiment. Therefore, since the other structure of the laser processing apparatus 10b is the same as that of the laser processing apparatus 10, illustration is abbreviate | omitted.
Further, since the optical system 20b is configured to include the condensing element 14 and the optical element 16b as in the laser processing apparatus 10, the illustration is omitted.

  As shown in FIG. 5A, the optical element 16b according to the present embodiment includes a plurality of quartz rods, that is, quartz rods 22a, quartz rods 22b and quartz rods 22c arranged so as to intersect the quartz rods 22a, and quartz. The holding mechanism 18 that fixes each of the rods 22a, 22b, and 22c is included.

  As shown in FIG. 5B, the spot S by the optical element 16b has a shape in which not only the slit portion B formed by the quartz rod 22a but also the peripheral portion is deleted by the quartz rods 22b and 22c. Thus, according to the laser processing apparatus 10b and the optical system 20b according to the present embodiment, for example, the spot S including the peripheral portion is mounted by fixing the optical element 16b during the processing torch of the laser processing apparatus 10b. The shape of (irradiation pattern) can be set more finely.

[Fourth Embodiment]
With reference to FIGS. 6-8, the laser processing apparatus 70 which concerns on this Embodiment is demonstrated. The laser processing apparatus 70 is a form in which the laser processing apparatus according to the present embodiment is applied to build-up processing. As shown to Fig.6 (a), the laser processing apparatus 70 adds the metal powder supply mechanism 30 for performing build-up processing to said laser processing apparatus 10. As shown in FIG. Therefore, since the laser processing apparatus 10 including the laser light source 12, the condensing element 14, and the optical element 16 is the same as the laser processing apparatus 10 according to the above-described embodiment, detailed description thereof is omitted.

  The metal powder supply mechanism 30 includes a nozzle 32, a metal powder source (not shown) and its transport unit, a transport gas and its transport unit, a shielding gas and its transport unit.

  As shown in FIG. 6A, the nozzle 32 includes a metal powder / carrier gas flow path 34 for supplying metal powder as a build-up member as a powder mixed gas PG together with a carrier gas (for example, nitrogen gas), A shield gas flow path 36 for supplying a shielding gas SG (for example, nitrogen gas) for shutting off the processing work site from the outside during the build-up processing is provided. As shown in FIG. 6B, the nozzle 32 has a configuration in which the metal powder / carrier gas channel 34 and the shielding gas channel 36 are arranged concentrically when viewed from the + Y direction. In the laser processing apparatus 70, the metal powder is ejected from the nozzle 32 while irradiating the processing beam with the light beam L to perform the overlay processing. At this time, the work site where the build-up process is performed is shielded with the shielding gas SG so that the periphery of the work site is maintained in the atmosphere of the carrier gas.

  In the build-up processing, a material (build-up member) supplied in the form of powder or wire is melt bonded to the surface of the base material. The energy density of the spot S in the build-up process is sufficient to melt the build-up member, and the amount of heat input is suppressed as much as possible, and the heat-affected zone (influence of the heat input upon heat input) It is desirable that the range is as narrow as possible (distortion due to heat input to the base material is minimized). In addition, in the build-up processing, a so-called dilution phenomenon in which the molten base material diffuses into the build-up member inevitably occurs to some extent. However, when the diffusion of the base material progresses excessively and the area of the diluted portion becomes large, there arises a problem that cracks occur in the build-up portion, and the characteristics of the build-up portion deteriorate and become hard and brittle.

  Regarding the above point, the energy density of the spot S of the laser processing apparatus according to the prior art that does not use the optical element 16 and the optical system 20 is generally such that the energy of the laser light source is concentrated in the central portion of the spot S. The energy density of the spot S according to such a conventional technique does not necessarily coincide with the energy density suitable for overlaying processing that requires the energy density as described above. In addition, there is a conventional technique in which the light intensity distribution of the spot S is made uniform, but even if such a light intensity distribution is adopted, it tends to be overheated at the central portion.

  Therefore, in the laser processing apparatus 70 according to the present embodiment, the energy density of the processing point and the spot S in the vicinity of the processing point is optimized in the overlay processing by using the action of the optical element 16 and the optical system 20. It is adjusted. More specifically, by suppressing the energy density in the vicinity of the center of the spot S, that is, by dispersing the energy in the vicinity of the linear center on both sides, the processing point and the heat input distribution in the vicinity of the processing point are made uniform. It is trying to become. As a result, the concentration of heat at the processing point and in the vicinity of the processing point is alleviated, and the build-up member is uniformly melted, and the base material is prevented from being melted too much, thereby obtaining a high-quality build-up product. it can.

  Next, with reference to FIG. 7 and FIG. 8, the case where the build-up processing by the laser processing apparatus 70 is applied to the formation of the valve seat of the cylinder head of the engine (internal combustion engine) will be described in detail. . Fig.7 (a) is sectional drawing which shows a cylinder head, FIG.7 (b) is a perspective view for demonstrating build-up processing. FIG. 8 is a diagram showing a cross-sectional state of the built-up portion formed by the build-up processing in comparison with a cross-sectional state of the built-up portion according to the conventional technique.

  As shown in FIG. 7A, a valve seat 66 formed by overlaying is provided on the peripheral edge of the air supply / exhaust valve hole 64 of the cylinder head 60 constituting a part of the engine. The valve 68 abuts on or separates from the valve seat 66, and intake and exhaust are performed during engine operation. Therefore, the valve seat 66 must have high hardness, and the valve seat 66 is required to have airtightness and wear resistance. The build-up processing using the laser processing apparatus 70 according to the present embodiment can be suitably used for forming a valve seat that requires such characteristics.

  As shown in FIG. 7B, the cylinder head 60 is provided with four supply / exhaust valve holes 64 as an example. A seat surface 62 is formed at the peripheral edge of each air supply / exhaust valve hole 64. The sheet surface 62 may be provided with a groove for forming a built-up portion. In the present embodiment, an example in which the cylinder head 60 is formed of aluminum and the valve seat 66 is formed of copper will be described. The aluminum forming the cylinder head 60 may be an aluminum alloy, and the copper forming the valve seat 66 may be a copper alloy. Of course, the combination of metals is not limited to these, and other metal combinations may be applied.

  When performing the build-up processing, as shown in FIG. 7B, the powder mixed gas PG is ejected from the nozzle 32, and the metal powder (copper powder in the present embodiment) contained in the powder mixed gas PG is used. The light beam L from the laser light source 12 is irradiated. The copper powder heated by the irradiation of the light beam L is melted and sintered to form a copper overlay on the sheet surface 62. The valve seat 66 is formed by forming the build-up portion along the peripheral edge of the air supply / exhaust valve hole 64. Similarly, the aluminum on the sheet surface 62 heated by the irradiation of the light beam L is also melted, and an alloy layer is formed below the build-up portion. In FIG. 7B, the nozzle 32 shown in FIG. 6 is limited to the metal powder / carrier gas flow path 34 in order to avoid complexity.

  With reference to FIG. 8, the cross-sectional structure of the valve seat 66 formed using the laser processing apparatus 70 according to the present embodiment will be described.

  FIG. 8A shows a cross-sectional structure of the valve seat 66 made of copper formed on the aluminum base material 84 by the laser processing apparatus 70. As shown in FIG. 8A, the valve seat 66 has a built-up portion 80, and a copper-aluminum alloy layer (diluted layer) is formed below the built-up portion 80 so as to bite into the base material 84. ) 82 is formed. The alloy layer 82 is formed at a site where heat is input by the laser light source 12, and the contour shape of the alloy layer 82 is substantially equal to the heat affected zone.

  As shown in FIG. 8A, the shape of the alloy layer 82 of the valve seat 66 according to the present embodiment is a simple concave shape (saddle shape) having no steps. This is due to the effect of uniformizing the heat input distribution near the processing point and the processing point by suppressing the energy density of the spot S at the processing point and in the vicinity of the processing point in the formation of the valve seat 66. It is.

  On the other hand, FIG. 8B shows a valve seat 66a formed on the base material 84 by the laser processing apparatus according to the prior art. The valve seat 66a also has a build-up portion 80a, and an alloy layer 82a is formed below the build-up portion 80a.

  As shown in FIG. 8B, the shape of the alloy layer 82 a of the valve seat 66 a is different from the alloy layer 82 of the valve seat 66 and has a step portion D. As described above, this is because the energy density of the beam spot of the laser processing apparatus according to the prior art is relatively high in the central portion, and therefore excessive heat is input in the central portion of the processing point. If there is such an excessively heated step portion D, the alloy layer 82a at that portion becomes brittle. Since the alloy layer 82 of the valve seat 66 according to the present embodiment has a simple saddle shape that does not have the step portion D or the like, the occurrence of such a problem is suppressed.

  In the above-described embodiment, the optical element is described by using a quartz rod or a metal mask as an example. However, the present invention is not limited thereto, and other materials such as a dielectric multilayer film may be used. Good. The dielectric multilayer film is a reflector having a reflective film in which dielectric thin films having a high refractive index and a low refractive index are alternately laminated on a substrate such as glass. The dielectric multilayer film can design the reflectance with respect to the wavelength of the laser beam of a laser processing apparatus by changing the material which comprises a multilayer film, and its film thickness. The beam profile (the shape of the spot S) at the condensing point can be adjusted by reflecting the light beam L being collected using such a dielectric multilayer film.

  In the optical element using the quartz rod, the light intensity in the slit portion B is significantly suppressed, whereas the optical element using the dielectric multilayer film can change the transmittance of the dielectric multilayer film with respect to the wavelength of the laser light source. Therefore, the light intensity profile at the condensing point can be finely adjusted. Therefore, the processing characteristics (heat input characteristics) can be controlled more precisely.

10, 10a, 10b Laser processing device 12 Laser light source 14 Condensing element 16, 16a, 16b Optical element 18 Holding mechanism 20, 20a, 20b Optical system 22a, 22b, 22c Quartz rod 30 Metal powder supply mechanism 32 Nozzle 34 Metal powder / Carrier gas flow path 36 Shielding gas flow path 60 Cylinder head 62 Seat surface 64 Air supply / exhaust valve holes 66, 66a Valve seat 68 Valve 70 Laser processing devices 80, 80a Overlay portion 82, 82a Alloy layer 84 Base material 100, 102 Quenching Part 104 Metal base material B Slit part C Concave part D Step part L Light flux P Processing point PG Powder mixed gas SG Shielding gas S Spot W Workpiece

Claims (11)

A laser light source;
A condensing unit that condenses the light beam generated from the laser light source toward the workpiece;
A light beam conversion unit including an optical element having non-uniform transmittance with respect to the light beam collected by the light collecting unit and making the light intensity distribution at the light collecting point non-uniform;
A laser processing apparatus comprising: The laser processing apparatus according to claim 1, wherein the optical element is formed of cylindrical quartz. The shape of the light intensity distribution has a substantially circular outer shape, and the light intensity distribution is made non-uniform by having a low light intensity region in the diameter direction of the circular shape. The laser processing apparatus as described. The laser beam machining apparatus according to claim 1, wherein the light beam conversion unit includes a plurality of the optical elements. The laser processing apparatus according to any one of claims 1 to 4, further comprising a collimating unit that collimates light generated from the laser light source between the laser light source and the condensing unit. Further comprising a build-up processing unit provided with a build-up member supply unit for supplying a build-up member for performing build-up processing,
The build-up processing unit supplies the build-up member on the workpiece from the build-up member supply unit while relatively moving the build-up member supply unit, the light flux, and the workpiece. The laser processing apparatus according to claim 1, wherein the supplied build-up member is irradiated with the light flux to perform build-up processing. The laser processing apparatus according to claim 6, wherein the build-up processing unit performs the build-up processing to form a valve seat of a cylinder head for an internal combustion engine. A condensing unit that condenses the luminous flux generated from the light source;
An optical element having a non-uniform transmittance with respect to the light beam collected by the light condensing unit, and a non-uniform light intensity distribution at the light collecting point;
Including optical system. Condensing the light beam generated from the laser light source toward the workpiece by the condensing unit,
A laser processing method in which a light intensity distribution at a condensing point is made non-uniform by a light beam converting unit including an optical element having a non-uniform transmittance with respect to the light beam condensed by the light collecting unit. By the build-up processing part provided with the build-up member supply part which supplies the build-up member for performing build-up processing, the said build-up member supply part, the said light beam, and the said workpiece are moved relatively. The laser processing method according to claim 9, wherein the build-up member is supplied from the build-up member supply unit onto the workpiece and the build-up member is irradiated with the light beam to perform build-up processing. . A base material made of a first metal;
A built-up portion formed of a second metal on the base material;
An alloy part that melt-joins the base material and the build-up part disposed between the base material and the build-up part;
And a build-up product in which the shape of the joint surface between the base material and the alloy part is a bowl shape,
When the build-up member is supplied on the base material, the build-up part and the alloy part are focused by the light collection unit on the light beam generated from the laser light source toward the workpiece. The above-mentioned surfacing supplied by making the light intensity distribution at the condensing point non-uniform by the light beam converting unit including an optical element having a non-uniform transmittance with respect to the light beam condensed by the light unit A build-up product formed by irradiating a member with the light beam and performing build-up processing.