JP2015047638A - Laser processing method using beam branched rotary optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser processing method capable of performing grinding, cutting, drilling and groove processing of composite material reinforced with fiber such as carbon fiber or glass fiber or a metal member of which the surface is coated with resin at a high speed and with high quality.SOLUTION: A laser 6 having two kinds of oscillation characteristics or different wavelength is branched by using a processing optical system such as DOE (diffraction optical element) 8; the branched lasers are synthesized (superimposed), while being condensed and rotated, together with another laser beam 1 while aligning an optical axis with the laser beam 1 by using a specific metal mirror 3, and are applied to a work 12, and thereby removal processing or joint of composite material such as metal plates coated with resin and fiber reinforced resin, which has not been possible in the conventional technique, is made possible, and the efficiency of laser processing is improved.

Description

  The present invention relates to a technical field for performing laser processing of a fiber reinforced composite material such as CFRP, and relates to a processing optical system related to branching and / or rotation / synthesis of a laser beam, and processing using the same. Two types of lasers with different properties are split by using a processing optical system such as DOE (diffractive optical element), and while rotating at high speed, another laser beam and optical axis are combined together using a special metal mirror. In addition, the present invention relates to a method for irradiating a workpiece to enable removal processing and welding of a composite material such as a resin-coated metal plate and fiber reinforced resin, which has not been possible in the past, and to increase the efficiency of laser processing. This technology has proposed a new technique for laser processing of complex materials such as CFRP and CFRM that are difficult to process and various coating materials.

Realizing light weight, high performance, high efficiency, resource saving and recycling in order to solve the current energy, environmental, and resource problems of industries such as automobiles, aircraft, ships, and railway vehicles. Development of processing technology for fiber reinforced composite materials represented by CFRP composite materials as a new material that can be used is screamed.
In recent years, fiber reinforced composite materials such as CFRP and GFRP have already been applied to airframes, car bodies and parts in the aircraft and automobile industries. Currently, for the drilling and cutting, diamond cutters, mechanical cutting / drilling using a diamond-coated cutting tool, and water jet cutting are used. However, since composite materials such as CFRP composite material and FRM composite material have different materials and physical properties of the matrix and the reinforcing material, removal processing such as cutting, drilling and grooving is not easy. For example, when cutting with a diamond tool, if the carbon fiber is scattered in the air, the operator sucks it, which causes a serious problem to the human body. Further, the wear of expensive cutting tools is easily damaged, and the processing cost becomes expensive. Further, when many fine holes are made in electrical products and machine parts made of metal and a composite material of metal and nonmetal, if the hole diameter is 50 μm or less, mechanical drilling with a drill becomes difficult. In water jet cutting, the machine is very expensive, and there is a problem that the abrasive used after cutting needs to be separated from water.

  Japanese Patent No. 4734437   Japanese Patent Application No. 2010-210422   Japanese Patent Application No. 2011-056622

  It is very difficult to perform cutting, cutting, drilling, and grooving of a composite material reinforced with fibers such as carbon fiber or tempered glass or a metal member whose surface is resin-coded at high speed and high quality. For example, in machining such as diamond cutter and water jet cutting, it is very difficult to cut a CFRP composite material having a thickness of 2 mm at 5 m / min. Moreover, it is very difficult to process a hole having a hole diameter of 50 μm or less. Even in the conventional laser processing method, there is a problem that the fibers on the cut surface are loosened and the processing speed is low. As a result, processing costs are very high and difficult to apply in the automotive industry. Therefore, the application field of composite materials is limited. In particular, when cutting a CFRP (carbon fiber reinforced plastic) material, there is a problem that fine carbon fibers are scattered in the air, causing problems on the human body in terms of safety and hygiene, and not only material costs but also processing costs are high.

Means to solve the problem

The present invention relates to a laser processing method that performs cutting, cutting, drilling, and grooving of composite materials reinforced with fibers such as carbon fiber and tempered glass, which are extremely difficult to cut and drill, at high speed and high quality, and the processing. An optical system is proposed.
In order to solve the above-described problem, the inventor used a diffractive optical element (hereinafter referred to as DOE) or a beam splitter to convert a laser beam oscillated from a solid-state pulse laser having a pulse width of 10 picoseconds or more and 100 nanoseconds or less. By using a condensing lens, multi-point branching of the beam and reduction of the beam diameter, etc., and irradiating the workpiece with multiple points, the processing speed can be increased by using multiple processing points as compared to irradiation for each point. We have devised a method to increase the processing speed by minimizing thermal damage to the composite material such as CFRP at each point, and rotating and scanning multiple multi-point beams at high speed.

  That is, when an object is irradiated with an ultrashort pulse laser having a pulse width of between 10 picoseconds and 100 nanoseconds with an output density of 0.1 GW / cm 2 or more and 25 GW / cm 2 or less, the laser light emits electrons in the atomic structure of the object. Since the surface of the object is heated to 8000 ° C or higher and the pulse duration is shorter than the thermal diffusion time of the substance, heat accumulation occurs on the surface, and near the irradiation surface of the material (substance) Only the heat is generated, and the heat causes the material to be heated, melted, and evaporated, resulting in ionization and plasma. As a result, when applied to a composite material such as CFRP, carbon fibers can be ablated with high cutting quality. Moreover, the same effect can be expected even when the composite material of metal and nonmetal is irradiated.

  However, the average output of the ultrashort pulse solid-state pulse laser is still low, and the processing speed is limited. Further, in the conventional processing using a continuous-wave high-power laser, there is a problem in cutting quality, such as a large amount of input heat and a slow heat escape rate in the CFRP cutting, causing separation of the resin and the reinforcing fiber. Therefore, a method for processing the above-described ultrashort pulse solid-state laser and a continuous-wave high-intensity (100 kW / mm2 or more) solid-state laser at a processing speed of 20 m / min or more using a special optical system has been devised. did. That is, in the trimming process of the member to be cut, the traveling speed of the corner portion is reduced to 1 m / min or less, so that it is difficult to process at a processing speed of 20 m / min or more with a continuous wave laser. The part that can be cut at a high speed of 20 m / min or higher is cut with a high-power (300 W or higher) high-intensity solid-state laser (for example, a single-mode fiber laser), and the low-speed traveling part such as a corner is a solid pulse laser with the above ultrashort pulse. Devised a method of cutting with high quality even at low speeds. In particular, when the fiber reinforced composite material has a thickness of 5 mm or more, the processing method using an ultra-short pulse laser is very slow and not industrial, so by using these together, a highly efficient laser processing method and processing system can be used. Is proposed.

  That is, a continuous-wave high-intensity solid wave that is branched into multiple points by a DOE 8 or a beam splitter 8 as shown in FIG. The reflecting surface 5 of the metal mirror 3 having a hole through which the laser 1 passes is irradiated, the beam is bent approximately 90 degrees, and the work surface 12 is irradiated. At this time, a laser processing system using different types of beams for irradiating the ultrashort pulse laser in a ring shape so as to partially overlap the periphery 14 of the beam spot (diameter of about 30 μm to 100 μm) 15 of the continuous wave high-intensity solid-state laser 1 This is a proposal.

  After condensing an ultrashort pulse laser with a condensing optical system and branching into 4 or 8 beams by DOE, each beam spot diameter is reduced to a range of 10 μm to 100 μm by the condensing optical system, and the installed DOE or beam The splitter holder 9 is rotated at a high speed by a motor 10 or the like, and is processed by irradiating the periphery of a continuous oscillation, high-intensity, high-power solid-state laser while rotating the multi-branched beam. In this case, when thick plate processing is performed using a single mode fiber laser with a high output of 3 kW or 5 kW, naturally, fiber peeling development occurs in the heat affected zone, but this is formed in a ring shape on the outer periphery of the beam. This is a laser processing system in which a solid pulse laser beam of ultra-short pulse rotating at high speed improves the quality of the processed surface by high-quality laser ablation processing.

  In the first aspect of the present invention, the laser beam transmitted from the solid-state pulse laser (laser A) device is branched into a plurality of parts by a diffractive optical element (DOE) or a beam splitter, and condensed by a condenser lens. Rotate each DOE or beam splitter holder, and irradiate the reflective surface (bottom surface of about 45 degrees) of the metal mirror with a vertical hole through which another type of solid-state laser (laser B) beam penetrates, making it totally reflected By bending the beam approximately 90 degrees and passing through the gas nozzle installed at the bottom of this metal mirror, aligning with the beam optical axis of laser B and irradiating the workpiece surface, it is a continuous oscillation high-intensity solid coming from another optical path A machining optical system that can be combined (superposed) with a laser (laser B) both spatially and temporally, and a laser machining method using this machining optical system.

According to a second aspect of the present invention, the laser A of the processing optical system according to the first aspect is a Q-switched YAG laser, a YVO4 laser, or a picosecond solid-state laser having a pulse width in the range of 10 picoseconds to 100 nanoseconds. The solid-state pulse laser includes a wavelength of 532 nm to 1080 nm, and after branching into a plurality of beams by DOE, the diameter of each beam spot is reduced to a range of 20 μm to 80 μm by a condensing optical system. The output density is set to 100 kW / mm 2 or more, the DOE lens holder is rotated at high speed with a motor or the like, the multi-branched beam is rotated, and the laser beam B of a continuous-wave high-power solid-state laser of 300 W or more is rotated. This is a laser processing system that irradiates the laser beam so that it partially overlaps (synthesizes) around the spot. Includes systems.

  The invention of claim 3 is the processing optical system according to any one of claims 1 and 2, wherein an ultrashort pulse laser of a solid pulse laser (laser A) is 0.1 GW / cm 2 or more and 25 GW / cm 2 or less. It is irradiated with a condensing lens so that the output density is about 50 μm to 100 μm on the surface of the object, and a portion around the beam spot diameter (about 30 μm to 80 μm) of the continuous wave solid-state laser (Laser B). This laser processing system uses two types of laser beams of different oscillation modes that irradiate the solid pulse laser (laser A) in a ring shape so as to overlap each other, and the solid pulse laser (laser A) and a continuous wave high output solid state In order to properly use the laser (laser B) according to the processing part of the workpiece, it is controlled in time by a sequencer, and (1) processing using only a solid pulse laser (2) Processing using a solid-state pulse laser and processing using a continuous-wave high-power solid-state laser with high brightness (100 kW / mm2 or more) and processing at a processing speed of 20 m / min or more, and (3) High brightness (100 kW / mm2) The processing system and the laser processing method are characterized in that the continuous oscillation high-power solid-state laser can be used in three ways, that is, processing at a processing speed of 20 m / min or more.

According to a fourth aspect of the present invention, in the machining optical system and the machining method according to any one of the first, second, and third aspects, the beam spot on the workpiece surface includes a stationary beam at the center and a rotating beam at the outer periphery. The present invention relates to a laser processing system which is partially synthesized and has a mechanism capable of adjusting the ratio of overlapping areas of two beams by adjusting the focal length of two laser beams (laser A and laser B).

The invention of claim 5 cuts, cuts, drills, grooves, cleans and joins a fiber-reinforced composite material using the processing optical system and laser processing method according to one of claims 1, 2, 3 and 4. The present invention relates to a laser processing method.

Invention of Claim 6 cuts and cut | disconnects the metal material and surface treatment member which carried out resin coating and metal coating using the processing optical system and laser processing method of any one of Claim 1, 2, 3 and 4 Further, the present invention relates to a laser processing method for drilling, grooving, cleaning, and bonding.

The invention according to claim 7 is an inorganic material such as ceramic, gemstone, glass, sapphire, diamond, and various polymers, using the processing optical system and the laser processing method according to any one of claims 1, 2, 3, and 4. The present invention relates to a laser processing method for cutting, cutting, drilling, grooving, cleaning and bonding.

The invention of claim 8 cuts and cuts dissimilar materials having different laser absorption rates above and below the surface using the processing optical system and laser processing method according to any one of claims 1, 2, 3 and 4. Further, the present invention relates to a laser processing method characterized by drilling, grooving, cleaning and joining.

Effect of the invention

In the past, it was very difficult to cut, cut, drill, and groove high-quality composite materials reinforced with fibers such as carbon fiber and tempered glass, and metal members with resin-coated surfaces. By using the technology of the present invention, it becomes possible to cut a CFRP composite material having a thickness of 2 mm at 5 m / min, improving the cutting accuracy of the cut surface, and improving the processing speed, thereby reducing the processing cost. As a result, laser processing of difficult-to-cut materials becomes possible in the automotive industry and industrial machinery fields. In addition, the processing environment is improved and the safety and health of the operator is ensured.
It is expected that not only CFRP (carbon fiber reinforced plastic) but also resin-coated metal plates can be easily laser processed.

  It is explanatory drawing explaining 1st Embodiment, and shows the front view of the processing optical system which branches and rotates two types of lasers.   It is explanatory drawing explaining 1st Embodiment, and is a top view which shows the relationship between a process table, a workpiece | work, and a laser beam spot.   It is explanatory drawing explaining 1st Embodiment and is a figure which shows the relationship between the oscillation time of two types of lasers, and the sequence control in a corner part.   It is explanatory drawing explaining 2nd Embodiment, and shows the photograph of the battery case made from CFRP which cut | disconnected the corner part with the ultra-short pulse solid-state laser and the linear part with the high-intensity solid-state laser.   It is explanatory drawing explaining 3rd Embodiment and shows the processing condition of the steel plate by which resin coating was carried out.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

In Example 1, a case where a rectangular CFRP composite material 12 is laser cut along a cutting line having a corner portion using the processing optical system of the present invention will be described with reference to FIGS.
The processing optical system shown in FIG. 1 splits a laser beam 6 transmitted from an ultrashort solid-state laser (laser A) device into a plurality of beams by a diffractive optical element (DOE) 8 or a beam splitter 8, and then collects a condensing lens 7. The reflecting surface of the metal mirror 3 having a vertical hole 4 through which another kind of solid-state laser (laser B) beam 1 penetrates while being constrained and rotated by a motor for each holder 9 of the DOE or beam splitter. By irradiating the bottom surface 5), bending the beam approximately 90 degrees, passing through the gas nozzle 11 installed at the lower part of this metal mirror, aligning the beam optical axis of the laser B1, and irradiating the surface of the workpiece 12, Combined with a continuous-wave, high-intensity, high-power solid-state laser (Laser B) 1 in service through a condensing lens 2 from another optical path and through a vertical hole in a metal mirror, both spatially and temporally on the workpiece surface Rukoto a machining optical system capable.

When this machining optical system is used, as shown in FIG. 2, when cutting on the cutting line 16 of the CFRP composite material, when cutting the vertical and horizontal straight line portions, a continuous oscillation high brightness high output solid The processing table 13 is moved and cut at a high speed of 20 m / min or more with only the laser (laser B), or when the plate is thick, the solid laser (laser A) with an ultrashort pulse is rotated and the continuous oscillation is high in brightness. Using a high-power solid-state laser (Laser B) in combination, cutting is repeated. However, if it is close to the corner portion, there is a possibility that the traveling speed is lowered as shown in FIG. 3. In this portion, the laser output of the continuous oscillation high-intensity high-power solid-state laser (Laser B) is lowered, and on the contrary The cutting quality can be ensured by increasing the output of the short pulse solid-state laser (laser A) and cutting only with the solid-state pulse laser. If it passes through the corner portion, the laser output of the continuous-wave high-intensity high-power solid-state laser (Laser B) is increased again, and cutting is performed at high speed. Depending on quality requirements, a rotating ultrashort pulsed solid state laser (Laser A) beam is utilized.
These time changes are schematically shown in FIG. In particular, if the laser output of laser B is increased by cutting a thick plate, the resin around the cutting groove 17 is thermally damaged. Thus, by using such an ultrashort pulse solid laser (laser A) beam, the quality can be improved. The final cut groove 18 has a high quality cut surface.

Example 2 is an example of the CFRP battery case shown in FIG. 4, in which only the corner portion was cut with an ultrashort pulse solid-state pulse laser, and the straight portion was laser cut with a high-intensity solid-state laser at a speed of 20 m / min. . The cutting quality at this time was good without loosening of the carbon fibers.

Example 3 is a case where a surface-treated steel sheet in which a resin is coded on the surface of the steel sheet is laser-cut using this technology in order to ensure corrosion resistance and chemical resistance. As shown in FIG. 5, the resin 20 is coated on the surface of the steel plate 19. Since the resin can be easily cut with a small heat input, high-quality cutting can be performed by using the rotated ultrashort pulse solid-state laser (laser A) beam 6. If the steel plate is 2 mm thick or more, a laser of kW or more is required, and high-speed cutting with good quality can be achieved by using a continuous-wave high-intensity and high-power solid-state laser (Laser B) 1.
Not only laser cutting, but also I-shaped butt welding of such steel sheets becomes easy. This is because the rotating ultrashort pulse solid-state laser (laser A) beam 6 is preceded, so that the resin layer on the surface is removed before welding the steel plate, so that welding can be performed as in normal laser welding. . It can also be applied to laser welding of aluminum plated steel sheets and galvanized steel sheets, and laser welding without porosity is also possible.

The present invention relates to laser processing (cutting, drilling, joining, cleaning, etc.) of a fiber reinforced composite material or resin or metal-coated member. Industrial applications include not only aircraft members but also automobiles, high-speed trains, ships, and architecture. Since it is used as a member for industrial machinery, aerospace equipment, parking facilities, pressure vessels, etc., the industrial application range is large.

1: continuous-wave high-intensity solid-state laser, 2: condenser lens 1, 3: metal mirror for photosynthesis,
4: beam through-hole, 5: reflecting surface, 6 solid-state pulse laser, 7: condenser lens 2,
8: DOE (diffractive optical element) or beam splitter, 9: DOE holder,
10: Rotating mechanism (motor), 11: Gas nozzle, 12: Workpiece,
13: processing table, 14: rotating beam spot, 15: stationary beam spot 16: cutting line, 17: cutting groove by stationary beam, 18: cutting groove by rotating beam 19: steel plate 20: resin or metal coating layer

Claims (8)

  The laser beam transmitted from the solid-state pulse laser (laser A) apparatus is converted into a plurality of laser beams branched by a diffractive optical element (DOE) or a beam splitter, and this is condensed by a condenser lens. Alternatively, while rotating with the holder of the beam splitter, the reflective surface (bottom surface of about 45 degrees) of a metal mirror having a vertical hole through which another kind of solid-state laser (laser B) beam passes is irradiated and totally reflected. A 90-degree beam is bent, passed through a gas nozzle installed at the bottom of this metal mirror, aligned with the beam optical axis of laser B, and irradiated onto the workpiece surface, so that a continuous-wave high-intensity solid-state laser (from another optical path) A processing optical system that can be combined spatially and temporally with the laser B) and a laser processing method using this processing optical system. The laser A of the processing optical system and the laser processing method has a pulse width in the range of 10 picoseconds to 100 nanoseconds and a wavelength of 532 nm to 1080 nm in the range of Q-switched YAG laser, YVO4 laser, pico This is a solid-state pulse laser including a second solid-state laser. After branching into a plurality of beams by DOE, each beam spot diameter is reduced to a range of 20 μm to 80 μm, put into DOE, the beams are branched, and collected by a condenser lens. After the output density is set to 100 kW / mm 2 or more, the optical system is rotated with a motor such as a DOE lens holder or a beam splitter holder, and a multi-branched beam is rotated while rotating 300 W. Partly overlap (synthesize) the beam spot of laser B of the above continuous wave high power solid state laser The laser processing system according to claim 1, or the processing system in which the laser A and the laser B are replaced with each other.   With the laser processing system and the laser processing method, the solid pulse laser (laser A) ultrashort pulse laser is squeezed with a condensing lens so as to obtain an output density of 0.1 GW / cm 2 or more and 25 GW / cm 2 or less on the object surface. The solid pulse laser (Laser A) is ring-shaped so that it is partially overlapped with the periphery of the beam spot diameter (about 30 μm to 80 μm) of the continuous wave solid laser (Laser B). Is a laser processing system that uses two types of laser beams of different oscillation modes to irradiate the laser, and uses a solid-state pulse laser (laser A) and a continuous-wave high-power solid-state laser (laser B) depending on the processing site of the workpiece. Time-controlled by sequencer, (1) machining with solid pulse laser only, (2) processing with solid pulse laser And high-intensity (100 kW / mm2 or higher) continuous-wave high-power solid-state laser processing at a processing speed of 20 m / min or higher, and (3) high-intensity (100 kW / mm2 or higher) continuous-wave high-power solid-state laser The processing system and the laser processing method according to any one of claims 1 and 2, wherein a laser can be used for three types of processing, that is, processing at a processing speed of 20 m / min or more. In the laser processing system, the beam spot on the workpiece surface is partially synthesized (overlapped) with the stationary beam at the center and the rotating beam at the outer periphery, and the focal length of the two laser beams (laser A and laser B). 4. The laser processing system according to claim 1, further comprising: a mechanism capable of adjusting a ratio of overlapping areas of the respective beams by adjusting the angle. 5. The fiber-reinforced composite material containing carbon fiber is cut, cut, drilled, grooved, cleaned, and bonded using the processing optical system and the laser processing method. The laser processing method according to claim 1. Cutting, cutting, drilling, grooving, cleaning, and joining a member composed of a resin-coated and metal-coated or plated metal material and a surface-treated multilayer using the processing optical system and the laser processing method; The laser processing method according to any one of claims 1, 2, 3, and 4 Cutting, cutting, drilling, grooving, cleaning and joining of inorganic materials such as ceramics, gemstones, glass, sapphire, diamond, various polymers and their multilayered members using the processing optical system and laser processing method The laser processing method according to any one of claims 1, 2, 3, and 4   5. The dissimilar materials having different laser absorption rates at the upper and lower sides are cut, cut, drilled, grooved, cleaned, and bonded using the processing optical system and the laser processing method. Laser processing method described in any one of items