JP2015000434A - Laser processing method using beam branching and synthesizing optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure operator's safety and health as well as a reduction in material cost and processing cost, by performing high-speed and high-quality processing of machining, cutting, boring and grooving a composite material reinforced with fibers such as carbon fibers or reinforcement glass or a metal member with a resin-coated surface.SOLUTION: This invention, which is related to a technical field for laser processing of a fiber-reinforced composite material such as CFRP: uses a processing optical system such as a DOE (diffraction optical element) 8 to branch a laser beam into two kinds of laser beams of different qualities while keeping high-speed rotation of the branched laser beams; uses a special metal mirror 3 to synthesize them with other laser beam 1 in alignment of the optical axes of the branched laser beams and the other laser beam 1; and irradiates the synthesized laser beam onto a workpiece. This enables a conventionally impossible removal processing or welding of a composite material such as a resin-coated metal plate or a fiber-reinforced resin and enhances the performance of the laser processing.

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 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-mentioned problem, the inventor uses a diffractive optical element (hereinafter referred to as DOE) or a beam splitter to convert a laser beam oscillated from a solid pulse laser having a pulse width of 100 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. A method has been devised in which the thermal damage to the composite material such as CFRP at each point is minimized, and a plurality of multi-point beams are scanned at high speed to increase the processing speed.

  That is, when an object is irradiated with an ultrashort pulse laser having a pulse width of between 100 picoseconds and 100 nanoseconds at 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 metal having a hole through which a continuous oscillation high-intensity solid-state laser 1 passes while rotating a solid-state pulse laser 6 branched into multiple points by a DOE 8 or a beam splitter 8 as shown in FIG. The reflection surface 5 of the mirror 3 is irradiated, the beam is bent by approximately 90 degrees, and the workpiece 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 the beam into 4 or 8 with a DOE, each beam spot diameter is reduced to a range of 10 μm to 100 μm, and the DOE installed next to the condensing optical system Alternatively, the holder 9 of the beam splitter is rotated at high speed by a motor 10 or the like, and processing is performed by irradiating the periphery of a continuous oscillation, high-intensity, high-power solid-state laser while rotating the multipointed 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 that improves the quality of the machined surface by high-quality laser ablation processing using a solid-state pulse laser beam that rotates at a high speed.

  According to the first aspect of the present invention, a laser beam transmitted from a solid-state pulse laser (laser A) apparatus is condensed by a condenser lens, and then the laser beam is branched into a plurality by a diffractive optical element (DOE) or a beam splitter. Irradiate the reflection surface (bottom surface of about 45 degrees) of a metal mirror with a vertical hole through which another type of solid-state laser (laser B) beam passes while rotating as a DOE or beam splitter holder, A continuous oscillation high-intensity solid-state laser coming from another optical path by bending the beam approximately 90 degrees, passing through the nozzle installed at the bottom of this metal mirror, aligning the beam optical axis of laser B and irradiating the workpiece surface This is a processing optical system that can be combined spatially and temporally with (Laser B), and a laser processing method using this processing 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 100 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, each beam spot diameter is narrowed to a range of 20 μm to 80 μm, and the output density after focusing is 100 kW / After being made to be at least mm2, it is placed in the DOE, the DOE lens holder is rotated at high speed with a motor or the like, and the beam of the high-power solid-state laser with continuous oscillation of 300 W or more is rotated while rotating the multi-branched beam This is a laser processing system that irradiates so as to partially overlap (synthesize) around the spot. In this case, laser A and laser B are interchanged. Also includes processing 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.

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 synthesize | combines 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 condenses a laser beam 6 transmitted from an ultrashort pulse solid-state laser (laser A) device with a condenser lens 7 and then diffracts the laser beam into a diffractive optical element (DOE) 8 or A metal mirror having a vertical hole 4 through which another kind of solid-state laser (laser B) beam 1 passes while being constrained and rotated by a motor for each holder 9 of the DOE or beam splitter. 3 is reflected on the reflecting surface 5 (bottom surface of about 45 degrees), the beam is bent by about 90 degrees, and the beam 11 of the laser B1 is aligned through the nozzle 11 installed at the bottom of the metal mirror. By irradiating the surface with a continuous-wave high-intensity high-power solid-state laser (Laser B) 1 that has been operated by a condenser lens 2 through a separate optical path and passed through a vertical hole in a metal mirror, spatially A machining optical system that can also be synthesized by temporally a work surface.

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: condensing 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: Rotation mechanism (motor), 11: 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 (7)

  A laser beam transmitted from a solid-state pulse laser (laser A) device is condensed by a condenser lens, and the laser beam is divided into a plurality of beams by a diffractive optical element (DOE) or a beam splitter, and the DOE or beam splitter is used. While rotating for each holder, the reflective surface (bottom surface of about 45 degrees) of a metal mirror having a vertical hole through which another kind of solid laser (laser B) beam passes is irradiated, and the beam is bent by about 90 degrees. By passing through the nozzle installed at the bottom of this metal mirror, aligning the beam optical axis of laser B and irradiating the surface of the workpiece, it is spatially different from the continuous oscillation high-intensity solid-state laser (laser B) coming from another optical path. Machining optical system that can be combined with each other and a laser machining method using this machining optical system.   The laser A of the processing optical system and the laser processing method has a pulse width in the range of 100 picoseconds to 100 nanoseconds and a wavelength in the range of 532 nm to 1080 nm, a Q-switched YAG laser, YVO4 laser, pico This is a solid-state pulse laser including a second solid-state laser. After branching into multiple beams by DOE, each beam spot diameter is narrowed down to a range of 20 μm to 80 μm so that the output density after condensing becomes 100 kW / mm 2 or more. After that, put in the DOE, rotate the lens holder of the DOE at high speed with a motor, etc., rotating the beam with multi-point branching, around the beam spot of the laser B of the continuous wave high power solid-state laser of 300W or more The laser processing system according to claim 1, or the laser processing system according to claim 1, wherein irradiation is performed so as to overlap (synthesize). Processing system in which description laser A and laser B are interchanged.   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. This solid pulse laser (laser A) is ring-shaped so that it is partially overlapped with the periphery of the beam spot diameter (approximately 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 by the stationary beam at the center and the rotating beam at the outer periphery, and by adjusting 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.   The fiber-reinforced composite material is cut, cut, drilled, grooved, cleaned and bonded using the processing optical system and the laser processing method according to any one of claims 1, 2, 3 and 4. The laser processing method as described. 2. The cutting, cutting, drilling, grooving, cleaning, and joining of a resin-coated and metal-coated or plated metal material and a surface treatment member using the processing optical system and the laser processing method. The laser processing method according to any one of 3 and 4 The inorganic material such as ceramic, jewel, glass, sapphire, diamond and various polymers are cut, cut, drilled, grooved, cleaned and joined using the processing optical system and the laser processing method. The laser processing method according to any one of 2, 3, and 4