JP4848296B2 - Cylindrical inner peripheral surface periodic structure processing method and cylindrical inner peripheral surface periodic structure processing apparatus - Google Patents

Description

  The present invention relates to a processing method and apparatus for processing a periodic structure (nano-unit fine periodic grooves and dimples) on an inner peripheral surface of a cylindrical workpiece with a femtosecond laser processing machine, and more particularly to a cylindrical workpiece (for example, an engine) The cylinder inner peripheral surface and the cylindrical inner peripheral surface such as the bearing inner peripheral surface in FIG. 1 can be reasonably aligned without changing the regular shape of the periodic structure.

  In recent years, reduction of air pollution has been raised as the most important issue of global warming prevention measures. In particular, it is known that the main cause of air pollution is exhaust gas emitted from automobiles, and automakers are competing to develop low-emission vehicles in an international agreement. The destination is expected to spread worldwide through the development and commercialization of hybrid vehicles, electric vehicles, fuel cell vehicles, and the like. Under such circumstances, measures to improve automobile fuel efficiency and engine performance / durability include friction reduction between pistons and cylinders in the engine, reduction in bearing rotation friction, reduction in gear meshing friction, etc. It is desired to reduce the frictional resistance to the limit. In the processing method for reducing the frictional resistance of the sliding part (friction surface) or rotating part (rolling surface) of the engine to the limit, the surface of the surface is subjected to grooving of fine uneven stripes by the mechanical external force of the blade. In addition, a processing technique for applying a nano-periodic structure (continuous fine periodic grooves, discontinuous dimple depressions) with a femtosecond laser processing machine has been attracting attention and has been actively developed. An observation apparatus for determining whether or not the nano-periodic structure is correctly generated has also been developed.

  In the above femtosecond laser processing machine, a processing method for processing a periodic structure (for example, a fine periodic groove) is to irradiate a solid material surface with a low fluence ultrashort pulse laser (femtosecond laser) with polarization control. Thus, a fine structure having a size smaller than the wavelength of the irradiated laser is formed. And, by irradiating the surface of the solid material by linearly polarizing the ultrashort pulse laser, an elongated fine structure can be formed along the direction orthogonal to the polarization direction, and by irradiating it with circularly polarized light Is formed. The size of such a fine structure has a positive correlation with the wavelength of the laser to be irradiated, and there is provided one that controls the size of the fine structure by selecting the wavelength (see, for example, Patent Document 1).

  When the femtosecond laser is incident from the laser driving unit, the diffraction grating 3 that separates the laser into a plurality of light beams, the convex lenses 4 and 5 for causing the light beams separated by the diffraction grating 3 to interfere with each other, A cylindrical lens 6 disposed between the interference region and the convex lens 5 that intersect and interfere with each other, and an XYZ stage 8 that can dispose the processing base material 7 in the interference region in order to perform processing with a laser, A cylindrical lens 6 is provided that shapes the interference area into a flat area, concentrates the energy density, and can be finely processed by the material laser interaction of the processing substrate 7 and the interference area (for example, , See Patent Document 2).

  In addition, by irradiating the substrate with femtosecond laser pulses that interfere with each other, a one-dimensional and / or two-dimensional irradiation by femtosecond laser that creates a periodic microstructure with a minimum average dimension of 5 to 200 nm in the substrate. This is a method for creating a three-dimensional periodic fine structure, and irradiates silica glass with two femtosecond laser pulses having high density energy of 0.1 TW / cm 2 or more and interfering with each other, particularly at an oscillation wavelength in the near infrared region. Thus, a method of creating a one-dimensional periodic microstructure by irradiation with a femtosecond laser that creates periodic grooves having an average width of 5 to 50 nm in silica glass is provided (see, for example, Patent Document 3).

  In addition, a positioning unit that can be set so that the position of the arc start and end of the welding process for each layer is not pre-wrapped by attaching a position sensor consisting of a rotary encoder to the turning drive mechanism of the welding head. The position sensor is connected to the positioning unit, a sequence controller for sequentially controlling the welding process for each layer is connected to the positioning unit, and the positioning unit and the sequence controller are based on a detection signal from the position sensor. There has been provided a joint welded by multi-layer welding via a joint (see, for example, Patent Document 4).

  As a technique closer to the object of the present invention, there is provided a technique capable of reducing the frictional resistance on the surface of a metal object more than the current state. According to this metal sliding surface treatment apparatus, the sliding surface of a metal object is irradiated with a femtosecond laser to form a fine periodic structure, thereby reducing the frictional resistance of the sliding surface. Therefore, due to its nature, the processing size is uniform and the controllability is high, so that it is possible to reduce the frictional resistance of the sliding surface of the metal object more than the current level. In addition, since it is possible to reduce the frictional resistance of the sliding surface of any size, shape and material, it is possible to improve the performance of mechanical parts having the sliding surface. There is a big merit. (For example, see Patent Document 5).

JP 2003-211400 A JP 2003-334683 A JP 2003-57422 A JP-A-6-320270 JP 2004-360011 A

  In each of the above known examples, a processing method of a periodic structure (for example, a fine periodic groove) using a femtosecond laser is a technical content in which the surface of a one-dimensional flat plate is irradiated with a femtosecond laser to generate the fine periodic groove. Therefore, it is not possible to generate the above-described fine periodic groove on the inner wall surface of the cylinder having a three-dimensional shape and the sliding surfaces of the inner and outer rings of the bearing. Another known example (Japanese Patent Laid-Open No. 6-320270) is a method of automatically welding joints of reinforcing bars by multilayer welding so that the start position and end position of the welding arc for each layer do not wrap. Since the welding head is pivoted around the cylindrical workpiece, that is, around the outer periphery by the turning drive mechanism, the microscopic period is formed on the inner peripheral surface of the cylinder having a relatively thin diameter as in the present invention. There is a problem in that it cannot be applied immediately to a machining head that requires space saving for machining a grooving groove.

  If the output of the femtosecond laser oscillator is increased, the diameter of the focused spot at the processing point can be increased, and the nano-scale fine periodic groove can be processed over a wide range at a time. However, instead of the above micro periodic grooves, if one point such as dimple processing is intensively processed, the normal processing method will move the converging point to the position where the mechanical axis or optical system is to be processed each time. There is a need to. In this method, it becomes difficult to shorten the machining due to a long machining time. Furthermore, in the metal sliding surface treatment apparatus, only a fine periodic structure is formed on the surface of a planar metal plate. For this reason, the periodic structure cannot be formed into a three-dimensional curved surface such as a cylinder inner peripheral surface serving as a cylinder inner peripheral surface or a bearing inner peripheral surface.

  The problem of the present invention was made in view of the problems of the processing method and apparatus for processing a periodic structure with the above-described conventional femtosecond laser, and further, the metal sliding surface treatment apparatus. Specially for the inner peripheral surface of a cylindrical workpiece with a three-dimensional curved surface, high accuracy and high accuracy without disturbing the regular shape (same direction of grooves) of periodic structures (nano-unit fine periodic grooves and dimples) It is an object of the present invention to provide a processing method and apparatus capable of efficient alignment processing. More specifically, the present invention provides a method and apparatus for processing a fine periodic structure into a three-dimensional curved surface such as a cylinder inner peripheral surface serving as a cylinder inner peripheral surface or a bearing inner peripheral surface. In addition, the major objective of the present invention is to promote the technological development of parts processing that contributes to the energy-saving effect and life-span-proof effect by reducing the energy loss by reducing the sliding friction resistance of various industrial machines. This will greatly contribute to measures to prevent global warming.

  According to a first aspect of the present invention, there is provided a periodic structure processing method for an inner circumferential surface of a cylinder, wherein a linearly polarized femtosecond laser emitted from a femtosecond laser oscillator is guided into a rotatable first rotating cylinder. The polarization direction of linearly polarized light is changed by a λ / 2 plate arranged in one rotating cylinder, and arranged in a second rotating cylinder provided so as to be rotatable with the axis aligned with the first rotating cylinder. The femtosecond laser is condensed by the condensing lens and the reflecting mirror, and is advanced in the outer diameter direction, and the inner peripheral surface of the cylindrical workpiece gripped by the chuck means is opposed to the outer periphery of the reflecting mirror so as to face the femtosecond laser. The second workpiece is irradiated with a second laser, the first rotary cylinder having the λ / 2 plate is rotated by 1/2 with respect to one rotation of the second rotary cylinder having the reflection mirror, and the cylindrical workpiece is rotated. Periodic grooves on the inner peripheral surface of the same direction Alignment processing is performed.

  A periodic structure machining method for a cylindrical inner peripheral surface according to claim 2 is the periodic structure machining method for a cylindrical inner circumferential surface according to claim 1, wherein the chuck means holding the cylindrical workpiece is moved by a Z-axis drive means to the cylindrical workpiece. The femtosecond laser is irradiated to the inner peripheral surface of the cylindrical workpiece by a predetermined width by continuously or intermittently moving in the axial direction.

  The periodic structure processing method for a cylindrical inner peripheral surface according to claim 3 is the periodic structure processing method for a cylindrical inner peripheral surface according to claim 1 or 2, wherein a femtosecond laser directed toward the reflecting mirror is disposed in the second rotating cylinder. A dimple or mixed periodic structure is formed on the inner peripheral surface of the cylindrical workpiece by being incident on a dimple processing homogenizer or a mixing processing homogenizer disposed on the front side of the condenser lens. It is.

  The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 4 includes a femtosecond laser oscillator, a rotatable first rotating cylinder for introducing a linearly polarized femtosecond laser from the femtosecond laser oscillator, and the first rotating cylinder. A λ / 2 plate that is arranged in one rotating cylinder and changes the polarization direction of the femtosecond laser, a second rotating cylinder that is arranged with a rotation axis aligned with the first rotating cylinder, and the second rotation A condensing lens that is arranged in the cylinder and collects the femtosecond laser; a reflection mirror that is arranged on the tip side of the second rotating cylinder and refracts the femtosecond laser in an outer diameter direction; and the second rotating cylinder Rotation drive means for rotating the first rotary cylinder by half with respect to one rotation and chuck means for gripping the cylindrical workpiece at a predetermined position.

  The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 5 is the periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 4, wherein the cylindrical workpiece held by the chuck means is advanced and retracted in the axial direction. A Z-axis driving means is provided.

  The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 6 is the periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 4 or 5, wherein the periodic structure processing apparatus is disposed in the second rotating cylinder and on the front side of the condenser lens. A dimple processing homogenizer or a mixing processing homogenizer is arranged.

  According to a seventh aspect of the present invention, there is provided a periodic structure processing method for a cylindrical inner peripheral surface, wherein a linearly polarized femtosecond laser emitted from a femtosecond laser oscillator is guided into a cylinder, and a femtosecond is formed by a condensing lens and a reflection mirror in the cylinder. While concentrating the laser, it advances in the outer diameter direction, the inner peripheral surface of the cylindrical workpiece gripped by the chuck means faces the outer periphery of the reflecting mirror, and the femtosecond laser is irradiated to rotate the cylindrical workpiece. Thus, the periodic grooves are aligned in the same direction on the inner peripheral surface.

  The periodic structure processing method for a cylindrical inner peripheral surface according to claim 8 is the periodic structure processing method for a cylindrical inner peripheral surface according to claim 7, wherein the chuck means holding the cylindrical workpiece is moved by a Z-axis drive means to the cylindrical workpiece. The femtosecond laser is irradiated to the inner peripheral surface of the cylindrical workpiece by a predetermined width by continuously or intermittently moving in the axial direction.

  The periodic structure processing method for a cylindrical inner peripheral surface according to claim 9 is the periodic structure processing method for a cylindrical inner peripheral surface according to claim 7 or 8, wherein the femtosecond laser directed toward the reflection mirror is collected in the cylindrical body. A dimple or mixed periodic structure is formed on the inner peripheral surface of the cylindrical workpiece by being incident on a dimple processing homogenizer or a mixing processing homogenizer disposed on the front side of the optical lens.

  The apparatus for processing a periodic structure on the inner peripheral surface of a cylinder according to claim 10 includes a femtosecond laser oscillator, a cylinder for introducing a linearly polarized femtosecond laser from the femtosecond laser oscillator, and a linearly polarized light disposed in the cylinder. A condensing lens that condenses the femtosecond laser, a reflecting mirror that is disposed on the tip side of the cylinder and refracts the femtosecond laser in an outer diameter direction, chuck means for gripping the cylindrical workpiece at a predetermined position, and the chuck And a work rotation driving unit for rotating the means.

  The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 11 is the periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 10, wherein the cylindrical workpiece held by the chuck means is advanced and retracted in the axial direction. A Z-axis driving means is provided.

  The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 12 is the periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 10 or 11, wherein the periodic structure processing apparatus is for dimple processing in the cylinder and on the front side of the condenser lens. A homogenizer or a homogenizer for mixing is arranged.

The method and apparatus for processing a periodic structure of a cylindrical inner peripheral surface according to the present invention comprises the above-described constituent elements and operates as follows.
First, in claims 1 to 5, a method and apparatus for processing a nano-unit periodic structure on a three-dimensional curved surface of a cylindrical inner peripheral surface is a linearly polarized femtosecond laser emitted from a femtosecond laser oscillator. The femtosecond laser is linearly polarized in a perpendicular direction by a λ / 2 plate in the first rotating cylinder provided on the laser processing head, and is further rotated by the first rotating cylinder. It becomes a femtosecond laser that advances in the outer diameter direction while condensing the femtosecond laser by the condensing lens and the reflection mirror provided in the rotating cylinder. Thus, the femtosecond laser is emitted toward the inner peripheral surface of the cylindrical workpiece held by the chuck means (not rotated in this embodiment) around the outer periphery of the reflection mirror. Here, when the first rotating cylinder is rotationally driven by the rotation driving means with a half rotation amount of the second rotating cylinder, a fine periodic groove (for example, groove width = several hundred nm). ) Are aligned in the same direction. Further, in the above processing, when the chuck means for gripping the cylindrical workpiece is moved in the axial direction of the second rotating cylinder in synchronization with the output of the femtosecond laser by the Z-axis driving means, the femtosecond laser is moved to the cylindrical workpiece. The inner peripheral surface is irradiated with a predetermined width, and fine periodic grooves are aligned on the inner peripheral surface of the cylinder by a predetermined width in the same direction. The processing is also performed with a simple processing device.

  2ndly, in Claims 3 and 6, the periodic structure processing method and apparatus for the first cylindrical workpiece are the dimple processing homogenizer or the mixing processing homogenizer closer to the light source than the reflecting mirror in the second rotating cylinder. Since the linearly polarized light of the femtosecond laser can be made into a plurality of spots or a mixture of spots and a uniform energy distribution, dimples (for example, dimple hole diameter = several tens of μm) or A large number of periodic structures in which dimples and fine periodic grooves are mixed are processed to have a processing width of an arbitrary dimension. Moreover, the process is performed with a simple processing apparatus.

  Thirdly, in the method for manufacturing a periodic structure on the inner peripheral surface of the cylinder and the apparatus therefor, the linearly polarized femtosecond laser emitted from the femtosecond laser oscillator is guided to the laser processing head, It becomes a femtosecond laser which is fixed to the cylindrical body of the processing head and is condensed by a condenser lens provided in the cylinder and proceeds in the outer diameter direction by a reflection mirror at the tip. The femtosecond laser is emitted toward the inner peripheral surface of the cylindrical workpiece held by the chuck means on the outer periphery of the reflecting mirror. Here, when the cylindrical workpiece is rotated by the workpiece rotation driving unit with the reflection mirror stopped, the direction of the linearly polarized light irradiated on the inner peripheral surface of the cylindrical workpiece from the reflection mirror does not change, and the cylinder workpiece Fine periodic grooves (for example, groove width = several hundred nm) are aligned in the same direction on the inner peripheral surface of the workpiece. Further, in the above processing, when the chuck means for gripping the cylindrical workpiece is moved in the axial direction of the cylindrical body by the Z-axis driving means in synchronization with the output of the femtosecond laser, the femtosecond laser is moved to the inner peripheral surface of the cylindrical workpiece. The fine periodic grooves are aligned and processed in the same direction by a predetermined width on the inner peripheral surface of the cylinder. The processing is also executed by a simple processing apparatus with the cylindrical body of the laser processing head fixed.

  Fourthly, in the ninth and twelfth aspects of the present invention, the third method for processing a periodic structure of a cylindrical workpiece and its apparatus are provided with a dimple processing homogenizer or a mixing processing homogenizer closer to the light source than the reflecting mirror in the cylinder. Therefore, since the linearly polarized light of the femtosecond laser can be a plurality of spots or a mixture of spots and uniform energy distribution, dimples (for example, dimple hole diameter = several tens of μm) or dimples and fine A large number of periodic structures in which periodic grooves are mixed are machined to a machining width of an arbitrary dimension. The processing is also performed by a simple processing apparatus with the cylindrical body of the laser processing head fixed.

Thus, according to the periodic structure processing method and apparatus for a cylindrical inner peripheral surface according to claims 1 to 6, the periodic structure processing method and apparatus for fixing the workpiece side and rotating the reflection mirror side are provided. Therefore, the fine periodic grooves or dimples that become the periodic structure can be efficiently processed in a single or complex manner on the inner peripheral surface of the cylindrical workpiece having a three-dimensional shape. The processing width can be freely set.
Further, according to the periodic structure processing method and apparatus for a cylindrical inner peripheral surface according to claims 7 to 12, the periodic structure processing method and apparatus for fixing the reflecting mirror side and rotating the workpiece side are provided. The periodic structure processing method and the apparatus thereof can simplify the structure and operation, and can efficiently process the fine periodic grooves or dimples on the inner peripheral surface of the cylindrical workpiece in a single or combined manner. The processing width can be freely set.

  As a result, lubricating oil accumulates in a number of concave grooves on the contact surface between the cylinder inner peripheral surface and the piston ring in which the cylindrical workpiece is provided with fine periodic grooves or dimples and mixed grooves thereof, and the piston and cylinder in the engine It is possible to reduce the frictional resistance between them to the utmost limit, and to improve the fuel efficiency of the automobile to the maximum. Of course, various devices / parts other than the cylinder, for example, the inner peripheral surface of the bearing can be processed, and the rolling resistance can be reduced.

  Hereinafter, a periodic structure machining method and apparatus for machining a cylindrical inner peripheral surface of a cylindrical workpiece according to the present invention will be described with reference to the illustrated first embodiment. 1 is an overall configuration diagram of a periodic structure processing apparatus for a cylindrical inner peripheral surface, FIG. 2 is a schematic cross-sectional view of a reflecting mirror, FIGS. 3 and 4 are a cross-sectional view and an enlarged view of a main part of a laser processing head, FIG. 6 is an operation view of the λ / 2 plate and the reflection mirror, FIG. 7 is a configuration diagram of a laser processing head for processing a fine periodic groove, and FIG. 8 is a dimple. FIG. 9 is a configuration diagram of a homogenizer, FIG. 10 is an explanatory diagram of a moving method and a processing locus by advancing / retreating drive means, FIG. 11 is an enlarged photograph of a fine periodic groove, and FIG. 12 is a dimple. FIG.

  The outline of the periodic structure processing apparatus 100 on the inner circumferential surface of the cylinder, which is the first embodiment of the present invention (embodiment including a phase plate), will be described with reference to FIGS. The configuration includes a femtosecond laser oscillator 10 that oscillates a linearly polarized femtosecond laser LO, a laser processing head 20 that is a central part of a processing apparatus, and a cylindrical workpiece W that is detachably gripped by a chuck means 7 and three-dimensionally. And a work control table 3 that moves in directions (three directions of X axis, Y axis, and Z axis). First, the femtosecond laser oscillator 10 and the laser processing head 20 are mounted horizontally on the base 2 of the vibration isolator 1 in a horizontal posture. Since the femtosecond laser oscillator 10 is a well-known one, a detailed description thereof will be omitted and a brief description will be given. A laser oscillation unit 10A serving as an oscillation source, a fiber laser oscillator 10B for adjusting the oscillation, a pulse stretcher 10C, and a Ti : A sapphire regenerative amplifier 10D, a pulse compressor 10E, a laser power attenuator 10F, an excitation pulse green laser 10G, a power supply controller 10H, and a casing temperature stabilization cooling device 10I. The laser processing head 20 is connected to a laser output unit 20A equipped with an electromagnetic shutter ST that receives a femtosecond laser LO and arbitrarily cuts off output (output control) on the input side. Further, an outer cylinder 49A and an inner cylinder 49B are provided on the output side of the laser processing head 20, and a cylindrical workpiece W (for example, an inner peripheral surface of a cylinder in an engine, an inner peripheral surface of a bearing outer ring, etc.) is covered from the outside. Yes.

  The cylindrical workpiece W is held by the chuck means 7 of the workpiece control table 3 provided separately from the laser processing head 20. The work control table 3 includes an X-axis driving unit 30 that moves the cylindrical work W in the X-axis direction (the front-rear direction in the figure), and the cylindrical work W mounted on the X-axis driving means 30 in the Z-axis direction (the left-right direction in the figure). Z-axis drive means 9 to be moved, Y-axis drive means 5 mounted on a column 9A on the Z-axis drive means 9 and moved in the Y-axis direction (vertical direction in the figure), and workpiece rotation drive arranged on the front wall surface It consists of a part 5A and a gripping tool 7 arranged at the front part. Thus, the cylindrical workpiece W has the Y axis driving means 5 and the left and right X axes so that the axis (rotation center) O2 of the laser output unit 20A coincides with the axis (rotation center) O2. Position alignment is performed by a combined fine movement feed with the X-axis drive means 30 that moves in the direction of. The insertion depth position ZA of the cylindrical workpiece W with respect to the laser output unit 20A is the -Z-axis direction (left side direction in the drawing) or the Z-axis drive means 9 mounted on the X-axis drive means 30 in the front-rear direction. It is performed by slightly moving in the + Z-axis direction (right side in the figure). Further, in order to rotate the cylindrical workpiece W while receiving the femtosecond laser LO on the outer periphery of the inner cylinder 49B at the tip of the laser processing head 20, the inside of the workpiece rotation driving unit 5A on the Y-axis driving means 5 is set. The chuck means 7 is rotationally driven by a rotation control motor MM provided in the above. The driving of the upper and lower Y axes, the left and right X axes, and the front and rear Z axes is performed by guide rail members G1, G2, and G3, a Y axis feed motor M1, a Z axis feed motor M2, and an X axis feed motor M3. Done.

  Further, the periodic structure processing apparatus 100 on the inner peripheral surface of the cylinder includes control means 200 for driving and controlling the motors M1, M2, M3, MM, the shutter ST, a drive motor MO of the rotation drive means SD described later, and the like. I have. The general configuration and function of the control means 200 will be described. First, the entire periodic structure processing apparatus 100 is comprehensively managed by a computer and the central control unit CPU controls the operation control of the entire apparatus, and the motors MO, M1, M2, M3 are controlled by commands from the central control unit CPU. , NC control unit NC equipped with PC control function to program and operate drive control of MM and ST, and drive each motor MO, M1, M2, M3, MM and ST in response to a command from NC control unit NC It comprises a drive unit DD. Under the control of the control means 200 having these functions, each unit 3, 5, 9, 10, 20, 30, M1, M2, M3, MM and ST drive section DD are operated. Thus, the first rotating cylinder 41 provided with the λ / 2 plate P serving as the optical polarization element is rotated by a half rotation amount with respect to the second rotating cylinder 49 provided with the reflecting mirror M. Rotation driving means SD (details will be described later) to be driven are driven by a drive motor MO. Thus, the periodic grooves KM are aligned and processed in the same direction by irradiating the inner peripheral surface W1 of the inner peripheral body W without changing the direction of the polarization direction of the linearly polarized light of the femtosecond laser LO. Further, the inner peripheral body W is moved by the Z-axis driving means 9 on which the Y-axis driving means 5 for gripping the inner peripheral body W by the chuck means 7 in the axial direction O1 of the second rotating cylindrical body 49. By moving in the direction O2, the femtosecond laser LO is applied to the inner peripheral surface of the cylindrical workpiece W by a predetermined width, and the fine periodic grooves are aligned by a predetermined width. Furthermore, it is possible to rotate the Y-axis driving means 5, the first rotating cylinder 41, and the second rotating cylinder 49 based on a certain relationship, and the Z-axis driving means 9 can be moved forward and backward. Control operation that follows the inner peripheral surface of the entangled three-dimensional inner cylinder is possible.

  Subsequently, with respect to the laser processing head 20, the first rotating cylinder 41 which is the central part in FIGS. 3 and 4 is rotated so that both the cylinders are rotationally driven by a half rotation amount of the second rotating cylinder 49. The drive means SD and the optical system provided in both cylinders will be described. First, a support 40 for supporting the laser processing head 20 in a horizontal posture is fixed on the base 2 of the vibration isolator 1 with the rotation axis O1 in a horizontal direction and a seat plate 40A fixed by bolts B. Yes. On the rear end side (the right end in the figure) in the support body 40, a short, rotatable first rotating cylinder 41 is supported via bearing means, and a laser light source of the first rotating cylinder 41 is provided. The side is connected to the laser output unit 20A by a connecting cylinder 42 through bearing means. The connecting cylinder 42 includes a plano-concave lens R1 serving as an optical system, and a plano-convex lens R2 and a λ / 2 plate P serving as an optical polarization element are attached to the in-cylinder tip of the first rotating cylinder 41. . Further, a second rotating cylinder 49 is supported on the front end side (the left end in the figure) in the support body 40 via bearing means, and the first rotating cylinder 41 and the second rotating cylinder 49 are Rotated by the rotation driving means SD. That is, the pulley 43 is provided on the outer periphery of the first rotating cylinder 41, and this is connected by the pulley 44 (1/4 number of teeth of the pulley 43) attached to the rotating shaft 47 of the driving motor MO and the positive belt KB1. . The drive motor MO is held by a flange 46 projecting from the support body 40, and a rotary shaft 47 is rotatably supported by a bearing body 48 attached to the support body 40. On the front end side (outer peripheral body W side) in the support body 40, a short and rotatable second rotary cylinder 49 is supported via bearing means. A pulley 50 is provided on the outer periphery of the second rotating cylinder 49, and this is connected by a pulley 51 (1/2 number of teeth of the pulley 50) attached to the rotating shaft 47 of the drive motor MO and a positive belt KB2. As a result, the second rotating cylinder 49 is rotationally driven by a half amount of rotation of the first rotating cylinder 41. On the rear end side of the second rotating cylinder 49 in the cylinder, there are an iris I2 optical system and a triple slide type homogenizer H (a periodic groove homogenizer H1 and a dimple homogenizer H2 for improving energy efficiency). The plano-convex lens R3 is sequentially arranged. In addition, an outer cylinder 49A and an inner cylinder 49B that slides in the direction of the axis O1 are connected to the tip of the second rotating cylinder 49, and a reflection mirror M is attached to the tip of the inner cylinder 49B. It is arranged so that the angle can be adjusted by the dial fitting D so that the second laser LO is refracted in the outer diameter direction. Thus, the reflection mirror M is irradiated with the femtosecond laser LO as linearly polarized light in the outer diameter direction toward the outer peripheral surface of the outer peripheral body W. The inner cylinder 49B that slides with respect to the outer cylinder 49A has a function of adjusting the focal length of the femtosecond laser LO with respect to the reflection mirror M.

An outline of the overall configuration of the optical system in the laser processing head 20 will be described. First, when machining the fine periodic groove KM on the inner peripheral surface W1 of the cylindrical workpiece W, as shown in FIGS. 3, 6, and 7, the femtosecond from the laser output unit 20A of the femtosecond laser oscillator 10 is used. The laser LO travels through the iris A1, the shutter ST, and the plano-concave lens R1, and further travels through the plano-convex lens R2, the λ / 2 plate P, and the iris A2 in the first rotating cylinder 41 of the laser processing head 20, Furthermore, the periodic groove homogenizer H1 in the second rotating cylinder 49 reaches the reflecting mirror M at the tip through a plano-convex lens (condensing lens) R3. The reason why the periodic groove homogenizer is used is that the energy waveform of the femtosecond laser beam LO is that of a mountain-shaped quadratic curve shown in FIG. Therefore, as shown in FIG. 9 (c), the energy distribution can be shaped into a rectangle by the periodic groove homogenizer H1 that improves the characteristics, and the energy efficiency can be made 100% as much as possible. Therefore, the periodic groove homogenizer H1 can be omitted if energy efficiency is not a problem. Subsequently, the femtosecond laser LO bent in the outer diameter direction by the reflecting mirror M is applied to the inner peripheral surface W1 of the cylindrical workpiece W in the form of linearly polarized light (about 2 mm in diameter). That is, since the groove direction and the processing area of the fine periodic groove KM by the femtosecond laser light LO depend on the polarization direction and fluence (laser output energy) of the femtosecond laser, these must be controlled. . Therefore, when processing the inner peripheral surface W1 of the three-dimensional cylindrical workpiece W as in the periodic structure processing apparatus 100 of the present invention, the femtosecond laser is in a state where the fluence (laser output energy) is constant. The direction of the linear polarization of the light LO must be controlled as the reflecting mirror M rotates. More specifically, the λ / 2 plate P placed on the optical path of the first rotating cylinder 41 is adjusted by adjusting the rotational position of the λ / 2 plate P with the reflecting mirror M in the second rotating cylinder 49 to thereby adjust the femtosecond laser LO. The direction of the linearly polarized light is controlled. That is, as shown in FIG. 6, the λ / 2 plate P is rotated by half rotation θp with respect to one rotation (θh) of the reflection mirror M.
By doing so, the fine periodic groove KM is processed in a uniform direction (in the drawing, a direction substantially aligned with the axial direction of the cylindrical workpiece W) on the inner peripheral surface of the cylindrical workpiece W. (See Figures 6 and 7)

  If the λ / 2 plate P is additionally described, the femtosecond laser LO has a polarization component (S component and P component) in a direction orthogonal to the light beam. A phase plate is what gives a phase difference (changes to 1/4 wavelength and 1/2 wavelength) to this polarization component. A plate giving a phase difference of π / 2 (90 °) is called a λ / 4 plate, which converts linearly polarized light into circularly polarized light and conversely converts circularly polarized light into linearly polarized light. Also, a plate giving a phase difference π (180 °) is called a λ / 2 plate, and only the polarization direction of linearly polarized light is changed to the 90 ° direction. In the present invention, a λ / 2 plate P is used. For example, as shown in the enlarged photograph of FIG. 5, the λ / 2 plate P is obtained by attaching a transparent thin film G1 having an isotropic refractive index and thickness to a part of a flat glass plate G, or attaching a transparent thin film. In this configuration, a phase difference is created between the light transmitted through the non-attached part and the non-attached part. Therefore, the relationship between the linearly polarized femtosecond laser LO passing through the λ / 2 plate P and the reflecting mirror M and irradiating the inner peripheral surface W1 of the cylindrical workpiece W will be described with reference to FIG. By rotating the λ / 2 plate P with respect to the polarization direction of the femtosecond laser light LO, the polarization direction of the femtosecond laser light LO passing through the λ / 2 plate P can be changed by the rotation angle amount. Therefore, in order to process the inner peripheral surface W1 of the cylindrical workpiece W by rotating the reflection mirror M, as shown in FIG. 6, the λ / 2 plate P is moved with respect to two rotations (θh) of the reflection mirror M. By making one rotation (θp), the fine periodic grooves KM aligned in the uniform direction on the inner peripheral surface are processed.

  Next, when processing the dimple DP on the inner peripheral surface W1 of the cylindrical workpiece W, as shown in FIGS. 3, 6, and 8, the femtosecond laser beam from the laser output unit 20A of the femtosecond laser oscillator 10 is used. The LO travels through the iris A1, the shutter ST, and the plano-concave lens R1, and further includes a plano-convex lens R2 and a λ / 2 plate P in the first rotating cylinder 41 of the laser processing head 20, an iris A2 and a homogenizer H2 for dimple processing. Through the plano-convex lens (condensing lens) R3 in the second rotary cylinder 49 and reaches the reflection mirror M at the tip. Thereafter, the femtosecond laser light LO bent in the outer diameter direction by the reflecting mirror M is irradiated onto the inner peripheral surface W1 of the cylindrical workpiece W. That is, the dimple DP by the femtosecond laser LO is dimpled by the femtosecond laser LO in which the dimple processing homogenizer H2 is placed in the second rotating cylinder 49 on the optical path when the inner peripheral surface of the cylindrical workpiece W is processed. DP is processed. The dimple processing homogenizer H2 is a kind of hologram, as shown in FIG. 9A, and controls the energy distribution of the condensing part. That is, the dimple processing homogenizer H2 has fine irregularities on its surface, the light of the femtosecond laser LO passing through the irregularities is diffracted, and a large number of energy distributions (a plurality of spots S1 to S6 having a high energy density) are obtained. Cause it to occur. With this energy distribution, a dimple DP as shown in FIG. 8 is processed. Incidentally, if the homogenizer H3 for mixing and processing for mixing the fine periodic groove KM and the dimple DP is switched, as shown in FIG. 9D, a plurality of spots S1 to S1 having a uniform energy distribution SO and high energy density are obtained. S6 is present, and composite processing in which the fine periodic groove KM and the dimple DP are mixed is performed.

  If the configuration of the laser processing head 20 is briefly described again, the fine periodic grooves KM are aligned and processed in a uniform direction on the inner peripheral surface of the cylindrical workpiece W as shown in FIG. The configuration of the optical system of the laser processing head 20 shown in FIG. When the dimples DP shown in FIG. 8A are aligned in a uniform direction, the optical system of the laser processing head 20 shown in FIG. 8B is used. In order to carry out the above dimple DP processing without the dimple processing homogenizer H2, the processing of each dimple DP must be repeated several times at a focal point where the energy distribution of the femtosecond laser LO is concentrated at one point. I must. Therefore, it can be said that there is no practical value because the processing efficiency is extremely poor.

  The method and apparatus for processing a periodic structure of a cylindrical inner peripheral surface according to the present invention are composed of the above-described components and operate as follows. First, the periodic structure machining method for the cylindrical workpiece W is the same as that of the cylindrical workpiece W in the laser machining head 20 shown in FIG. 7 under the action of the λ / 2 plate P, the periodic groove homogenizer H1, and the reflection mirror M. The fine periodic groove KM is processed by irradiating the femtosecond laser LO toward the inner peripheral surface W1. That is, as shown in FIG. 2 to FIG. 4 and FIG. 7, the laser processing head 20 applies the femtosecond laser LO input to the laser output unit 20A to the λ / of the first rotary cylinder 41 by opening / closing control by the shutter ST. The light enters the two plates P. Subsequently, controllable linearly polarized light with improved energy distribution is obtained by the periodic groove homogenizer H1. Further, the femtosecond laser LO advances from the direction of the rotation axis O1 toward the outer periphery in the outer diameter direction by the reflection mirror M of the second rotating cylinder 49, and is irradiated toward the inner peripheral surface W1 of the cylindrical workpiece W. . At this time, the first rotating cylinder 41 and the second rotating cylinder 49 are rotated by the rotation driving means SD, and the laser output is synchronized with this rotation by the opening / closing control by the shutter ST. That is, as shown in the operation explanatory diagram of FIG. 6, when the first rotating cylinder 41 provided with the λ / 2 plate P is rotated, the second rotation including the first rotating cylinder 41 provided by a reflecting mirror is performed. The femtosecond laser LO is irradiated to the entire circumference of the inner peripheral surface of the cylindrical workpiece by rotating the cylindrical body 49 by a half rotation amount, and the fine periodic grooves KM having the nano-periodic structure are aligned in the same direction. Is done. At the end of processing, the shutter ST is closed to shut off the femtosecond laser LO. The processing result is as shown in FIG. That is, the femtosecond laser LO has an elliptical shape with a long longitudinal direction L (a beam width L of about 2 mm) and irradiates this toward the inner peripheral surface W1 of the cylindrical workpiece W, and the λ / 2 plate P is irradiated with the λ / 2 plate P. By rotating the reflecting mirror by a half rotation amount, the continuous periodic periodic grooves (processing width L of about 2 mm) KM are aligned and processed in the same direction.

  In the above processing, the chuck means 7 for gripping the cylindrical workpiece W is synchronized with the output of the femtosecond laser in the axial direction O1 of the second rotating cylinder 49 (open / close control by the shirter ST) by the Z-axis drive means 9. The femtosecond laser is applied to the inner peripheral surface W1 of the cylindrical workpiece by a predetermined width, and fine periodic grooves are aligned and processed in the same direction by a predetermined width on the inner peripheral surface W1. The processing is also performed with a simple processing device. That is, in the above operation, the processing width of the fine periodic groove KM in the axial direction O2 of the cylindrical workpiece W is set so that the cylindrical workpiece W is rotated by the chuck means by the rotation control motor MM in the workpiece rotation drive unit 5A. This is performed by advancing the Z-axis driving means 9 in the + Z-axis direction (second rotating cylinder 49 side). Accordingly, as shown in FIG. 10, the inner peripheral surface W1 of the cylindrical workpiece W is processed by two movement methods of the Z-axis driving means 9 and the processing locus thereof. That is, FIG. 10A shows a periodic structure with respect to the inner peripheral surface W1 by intermittent movement in which the Z-axis driving means 9 is repeatedly moved by one pick per predetermined amount every rotation of the second rotating cylinder 49. The body is processed to a predetermined width. Further, in FIG. 10B, every time the second rotating cylinder 49 rotates, the Z-axis driving unit 9 is continuously moved like a screw rod feed by a predetermined amount of one pick feed and processed into a spiral shape. Thereby, a periodic structure is processed into predetermined width with respect to inner peripheral surface W1. Thus, the fine periodic groove KM having a nano-periodic structure is machined into a machining width having an arbitrary dimension. Note that the processing width L of the fine periodic groove (processing width L of about 2 mm) KM is increased in proportion to the output of the femtosecond laser light LO. FIG. 11 shows a photomicrograph obtained by processing the fine periodic groove KM.

  Subsequently, the periodic structure processing method and apparatus 100 for the inner peripheral surface of the cylinder includes a dimple processing homogenizer between the λ / 2 plate P and the reflection mirror M as shown in FIGS. It can be set as the Example which has arrange | positioned H2. In this embodiment, as shown in FIG. 8, several spots S1 to S6 with high energy density are seen in the energy cross section of the femtosecond laser light LO. Thereby, the dimple DP other than the fine periodic groove KM is efficiently processed into the inner peripheral surface W1 of the cylindrical workpiece W. The machining width of the dimple DP in the direction of the axis O2 of the cylindrical workpiece W is performed by advancing the Z-axis driving means 9 in the + Z-axis direction while the cylindrical workpiece W is rotated by the workpiece rotation driving unit 5A. Thus, the dimples DP are arranged on the inner circumferential surface W1 of the cylindrical workpiece W so as to have a machining width of an arbitrary dimension. That is, as shown in FIGS. 10A and 10B, the Z-axis drive means 9 is moved by two moving methods and a machining locus method. FIG. 12 shows a micrograph obtained by processing the dimple DP.

  Therefore, if the cylindrical workpiece W is, for example, a cylinder block, a fine periodic groove KM (processing width L of about 2 mm, one groove width is several hundred nm) and dimple DP are separately provided on the inner peripheral surface of the cylinder. To be processed. Further, if the both are switched to the homogenizer H3 for mixed processing, as shown in FIG. 9 (d), a uniform energy distribution SO and a plurality of spots S1 to S6 with high energy density exist, and the fine periodic groove KM. And the dimple DP are mixedly processed. If the fine periodic groove KM and the dimple DP are processed into a cylinder which is one specific form of the cylindrical workpiece W, the contact area with the piston ring is reduced and a large number of concave grooves accumulate lubricating oil in the engine. It becomes possible to reduce the frictional resistance between the piston and the cylinder to the utmost, and the fuel efficiency of the automobile is improved to the maximum.

  As described above, according to the periodic structure processing method and apparatus for the cylindrical inner peripheral surface according to the first embodiment of the present invention, the following effects are exhibited. That is, since the periodic structure processing method and apparatus for fixing the cylindrical workpiece side and rotating the reflecting mirror side with respect to the inner circumferential surface of the three-dimensional cylindrical workpiece W are used, The fine periodic grooves or dimples that become the periodic structure can be efficiently processed in a single or complex manner. If the cylindrical workpiece W is also moved in the Z-axis direction, a fine periodic groove KM, dimple DP, or a mixed groove thereof can be efficiently formed on the inner peripheral surface W1 of the cylindrical workpiece W to have an arbitrary dimension of processing width. Can be processed.

  If the cylindrical workpiece W is, for example, a cylinder block, lubricating oil is accumulated in a large number of grooves, and the frictional resistance between the piston and the cylinder is efficiently reduced to the maximum in the entire stroke section of the piston reciprocating motion in the engine. Can do. Further, the rotational frictional resistance of the bearing can be reduced to the limit.

  Subsequently, a method of processing a periodic structure of an outer peripheral body and an apparatus 100 ′ thereof according to a second embodiment of the present invention will be described with reference to FIGS. In this periodic structure processing method and apparatus 100 ', the cylindrical body 49 and the reflection mirror M side are fixed, the λ / 2 plate P is omitted, and the cylindrical work W is rotated by the chuck means 7 for processing. is there. The overall configuration includes a femtosecond laser oscillator 10 and a laser processing head 20 for introducing a linearly polarized femtosecond laser LO emitted from the femtosecond laser oscillator 10. The laser processing head 20 condenses the femtosecond laser introduced therein by a condenser lens R3 via a homogenizer H (one of H1, H2, and H3), and in the outer diameter direction by a reflecting mirror M at the tip. A cylindrical body 49 is provided, and has a function of irradiating a femtosecond laser directed in the outer diameter direction toward the inner peripheral surface W1 of the cylindrical workpiece W disposed on the outer periphery of the reflection mirror by the reflection mirror. Furthermore, a workpiece control table 3 is provided around the outer periphery of the reflection mirror in the laser processing head 20 to hold the cylindrical workpiece W by the chuck means 7 and control this position. The work control table 3 is the same as that of the first embodiment, but will be described again. That is, the work control table 3 includes an X-axis drive means 30 for moving the cylindrical work W in the X-axis direction (the front-rear direction in the figure), and the cylindrical work W mounted on the X-axis driving means 30 in the Z-axis direction (the left-right direction in the figure). Z-axis driving means 9 to be moved in the direction, Y-axis driving means 5 mounted on the column 9A on the Z-axis driving means 9 to be moved in the Y-axis direction (vertical direction in the figure), and a work placed on the front wall surface The rotary drive unit 5A and the chuck means 7 arranged at the front part are included. Thus, the cylindrical workpiece W has the Y axis driving means 5 and the left and right X axes so that the axis (rotation center) O2 of the laser output unit 20A coincides with the axis (rotation center) O2. Position alignment is performed by a combined fine movement feed with the X-axis drive means 30 that moves in the direction of. The insertion depth position ZA of the cylindrical workpiece W with respect to the laser output unit 20A is the -Z-axis direction (left side direction in the drawing) or the Z-axis drive means 9 mounted on the X-axis drive means 30 in the front-rear direction. It is performed by slightly moving in the + Z-axis direction (right side in the figure). That is, from the Z-axis driving means 9 for moving the cylindrical work together with the chuck means 7 and the work rotation driving unit 5A in the axial direction O2 to irradiate the inner peripheral surface of the cylindrical work by a predetermined width. Become. Further, in order to rotate the cylindrical workpiece W while receiving the femtosecond laser LO on the outer periphery of the inner cylinder 49B at the tip of the laser processing head 20, the workpiece rotation driving unit 5A mounted on the Y-axis driving means 5 is used. The chuck means is driven to rotate by the rotation control motor MM. The driving of the upper and lower Y axes, the left and right X axes, and the front and rear Z axes is performed by guide rail members G1, G2, and G3, a Y axis feed motor M1, a Z axis feed motor M2, and an X axis feed motor M3. Done. The work control table 3 and the other units 10 and 20 are controlled by the control means 200. In addition, the detailed structure of another member attaches | subjects the same code | symbol as the periodic structure processing apparatus 100 of the said 1st Embodiment, and abbreviate | omits description.

  The cylindrical inner peripheral surface periodic structure processing apparatus 100 ′ according to the second embodiment of the present invention has the above-described configuration, and the cylindrical inner peripheral surface periodic structure processing method is performed as follows. The action is that the nano-periodic structure is processed on the inner peripheral surface of the cylindrical workpiece W without rotating the cylindrical body 49 and using a λ / 2 plate. Specifically, the femtosecond laser LO emitted from the femtosecond laser oscillator 10 is guided to the laser processing head 20 by opening and closing the shutter ST, and the femtosecond laser introduced into the cylindrical body 49 is converted into a periodic groove homogenizer. It becomes a femtosecond laser that progresses in the outer diameter direction by the reflecting mirror M at the tip while being condensed by the condenser lens R3 via H1. The femtosecond laser is irradiated toward the inner peripheral surface W1 of the cylindrical workpiece W held by the chuck means 7 on the outer periphery of the reflecting mirror. In synchronism with the output of the femtosecond laser (opening / closing control by the shutter ST), the cylindrical workpiece held by the chuck means 7 of the workpiece rotation driving unit 5A is rotationally driven by the rotation control motor MM of the workpiece rotation driving unit 5A. Is done. Thus, the continuous periodic fine periodic grooves KM are aligned in the same direction with respect to the inner peripheral surface W1 of the cylindrical workpiece W.

  Here, when the cylindrical work W is moved in the axial direction O2 by the Z-axis driving means 9 in synchronization with the rotation of the chuck means 7 by the work rotation driving unit 5A, the output of the femtosecond laser is synchronized with the cylindrical work W. The inner peripheral surface W1 of W is irradiated by a predetermined width, and fine periodic grooves are aligned and processed in the same direction by a predetermined width on the cylindrical inner peripheral surface. This processing is executed only by rotation of the cylindrical workpiece W and movement in the axial direction. At the end of the processing, the shutter ST is closed to shut off the femtosecond laser LO. As a result, the fine periodic grooves KM are aligned on the cylindrical inner peripheral surface W1 by a predetermined width in the same direction, and are executed by a simple processing apparatus. That is, as shown in FIG. 10 (a), the cylindrical workpiece W is moved relative to the inner peripheral surface W1 by intermittent movement in which the Z-axis driving means 9 repeats one pick feed every predetermined amount every rotation. Thus, the periodic structure is processed into a predetermined width. Further, as shown in FIG. 10 (b), if the Z-axis driving unit 9 is continuously moved like a screw feed by a predetermined amount of one pick feed for each rotation of the cylinder 49, it is processed into a spiral shape. Thereby, the periodic structure is processed into a predetermined width of an arbitrary dimension with respect to the inner peripheral surface W1. FIG. 11 shows an enlarged micrograph of the fine periodic groove KM.

  Further, in the method and apparatus 100 ′ for forming the periodic structure, the inner peripheral surface W1 of the cylindrical workpiece W can be obtained by switching the periodic groove homogenizer H1 in the cylindrical body 49 to another dimple processing homogenizer H2. The dimple DP is machined to a machining width of an arbitrary dimension. FIG. 12 shows an enlarged micrograph of the dimple DP. Further, when switching to another mixing homogenizer H3, the inner peripheral surface W1 of the cylindrical workpiece W is mixed with the fine periodic groove KM and the dimple DP in a processing width of an arbitrary dimension.

  According to the periodic structure processing method and the apparatus 100 ′ of the cylindrical inner peripheral surface according to the second embodiment of the present invention, the following effects are exhibited. That is, it is sufficient to control the rotation of the cylindrical workpiece and move it in the axial direction with an extremely simple apparatus and processing method without rotating the cylinder and using the λ / 2 plate. Periodic structures of various shapes can be easily processed into a three-dimensional curved surface such as the inner peripheral surface W1. The other effects can be expected to be the same as those of the periodic structure processing method for the cylindrical inner peripheral surface and the apparatus 100 according to the first embodiment.

  The method and apparatus for processing a periodic structure on the cylindrical inner peripheral surface of the present invention has been described in the processing example of the cylindrical inner peripheral surface. In the specific example, as a measure for improving the fuel consumption of an automobile, the friction between the piston and the cylinder is reduced by processing the cylinder inner peripheral surface of the engine. However, the present invention is not limited to the cylinder block, and it can be applied to reduce the rotational frictional resistance of the outer ring inner peripheral surface of other devices and bearings and the frictional resistance of the cylindrical inner peripheral surface. Furthermore, in the method and apparatus of the present invention, the design change of each part and the change / replacement of the constituent members within the gist of the invention can be freely performed. Specifically, in each of the above embodiments, the horizontal periodic structure processing apparatuses 100 and 100 'have been described. However, the femtosecond laser oscillator 10 is disposed on the upper side, the laser is emitted downward, and the lower part is disposed on the lower part. It is also possible to use a vertical periodic structure processing apparatus for processing a workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS It is the whole block diagram of the periodic structure processing apparatus of the cylindrical internal peripheral surface which shows the 1st Embodiment of this invention. 1 is a schematic cross-sectional view of a reflection mirror portion, showing a first embodiment of the present invention. 1 is a detailed cross-sectional view of a laser processing head according to a first embodiment of the present invention. 1 is a side view of a laser machining head drive system according to a first embodiment of the present invention. FIG. FIG. 2 is an enlarged photograph of a λ / 2 plate, showing the first embodiment of the present invention. FIG. 3 is a diagram illustrating the operation of the λ / 2 plate according to the first embodiment of the present invention. It is a block diagram of the laser processing head which shows the 1st Embodiment of this invention and processes a fine periodic groove | channel. It is a block diagram of the laser processing head which shows the 1st Embodiment of this invention and processes a dimple. BRIEF DESCRIPTION OF THE DRAWINGS It is the block diagram of the homogenizer which shows the 1st Embodiment of this invention. FIG. 2 is a diagram illustrating a moving method of an advance / retreat driving unit and a machining locus according to the first embodiment of this invention. It is an enlarged photograph figure of a fine periodic groove. It is an enlarged photograph figure of a dimple. It is a whole block diagram of the periodic structure processing apparatus of the cylindrical internal peripheral surface which shows the 2nd Embodiment of this invention. FIG. 5 is a detailed cross-sectional view of a laser processing head, showing a second embodiment of the present invention. It is a block diagram of the laser processing head which shows the 2nd Embodiment of this invention and processes a fine periodic groove | channel. It is a block diagram of the laser processing head which shows the 2nd Embodiment of this invention and processes a dimple.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Anti-vibration stand 2 Base | substrate 3 Work control table 5 Y-axis drive means 5A Work rotation drive part 7 Chuck means 9 Z-axis drive means 9A Column 10 Femtosecond laser oscillator 10A Laser generation part 10B Fiber laser oscillator 10C Pulse stretcher 10D Ti: sapphire regenerative amplifier 10E pulse compressor 10F laser power attenuator 10G wake-up pulse green laser 10H power supply control unit 10I housing temperature stabilization cooling device 20 laser processing head 20A laser output unit 30 X-axis drive means 40 support 41 first rotation Cylindrical body 42 Connecting cylinder 43 Pulley 44 Pulley 45 Holding body 46 Flange 47 Rotating shaft 48 Bearing body 49A Outer cylinder 49B Inner cylinder 49 Second rotating cylinder (cylinder)
50 Pulley 51 Pulley A1, A2 Iris CPU Central control part DD Drive part DP Dimple NC NC control part KM Fine periodic groove LO Femtosecond laser G1, G2, G3 Guide rail member KB1, KB2 Positive belt M1, M2, M3 Motor MO drive motor MM Rotation control motor M Reflection mirror H Homogenizer H1 Homogenizer for periodic grooves H2 Homogenizer for dimple H3 Homogenizers O1 and O2 for mixed processing
P λ / 2 plate RO Rotation R1 Plano-concave lens R2, R3 Plano-convex lens SD Rotation drive means SO Uniform energy distribution S1 to S6 Spot ST Shutter W Cylindrical work W1 Inner circumferential surface θh Rotation of reflection mirror θp λ / 2 Plate rotation ZA Insertion depth position -Z, + Z Z-axis direction 100 Periodic structure processing apparatus 100 'Periodic structure processing apparatus 200 Control means

Claims (12)

  A linearly polarized femtosecond laser emitted from the femtosecond laser oscillator is guided into a rotatable first rotating cylinder, and the polarization direction of the linearly polarized light is changed by a λ / 2 plate disposed in the first rotating cylinder. And the femtosecond laser is collected while being condensed by a condensing lens and a reflecting mirror disposed in a second rotating cylinder that is rotatably provided with the axis aligned with the first rotating cylinder. Advancing in the radial direction, the femtosecond laser is irradiated with the inner peripheral surface of the cylindrical workpiece held by the chuck means facing the outer periphery of the reflecting mirror, and the second rotating cylinder including the reflecting mirror The first rotating cylinder having the λ / 2 plate is rotated by 1/2 with respect to one rotation, and periodic grooves are aligned in the same direction on the inner peripheral surface of the cylindrical workpiece. Periodic structure on the inner circumferential surface Processing method.   The chuck means holding the cylindrical work is continuously or intermittently moved in the axial direction of the cylindrical work by the Z-axis driving means, and the femtosecond laser is irradiated to the inner peripheral surface of the cylindrical work by a predetermined width. The method for processing a periodic structure on the inner peripheral surface of a cylinder according to claim 1.   A dimple is introduced into the inner peripheral surface of the cylindrical workpiece by causing the femtosecond laser directed toward the reflecting mirror to enter the homogenizer for dimple processing or the homogenizer for mixing processing disposed in the second rotating cylinder and on the front side of the condenser lens. 3. A periodic structure processing method for a cylindrical inner peripheral surface according to claim 1, wherein a mixed periodic structure is formed.   A femtosecond laser oscillator, a rotatable first rotating cylinder for introducing a linearly polarized femtosecond laser from the femtosecond laser oscillator, and a polarization direction of the femtosecond laser arranged in the first rotating cylinder A λ / 2 plate, a second rotating cylinder arranged with the first rotating cylinder aligned with the rotation axis, a condenser lens arranged in the second rotating cylinder and condensing a femtosecond laser; A reflecting mirror disposed on the distal end side of the second rotating cylinder and refracting the femtosecond laser in the outer diameter direction; and the first rotating cylinder is halved with respect to one rotation of the second rotating cylinder. A periodic structure processing apparatus for an inner peripheral surface of a cylinder, comprising: a rotation driving means for rotating the cylindrical workpiece; and a chuck means for holding the cylindrical workpiece at a predetermined position.   5. The periodic structure processing apparatus for a cylindrical inner peripheral surface according to claim 4, further comprising Z-axis driving means for moving the cylindrical workpiece held by the chuck means back and forth in the axial direction.   6. The periodic structure processing apparatus for an inner peripheral surface of a cylinder according to claim 4, wherein a dimple processing homogenizer or a mixing processing homogenizer is disposed in the second rotating cylinder in front of the condenser lens.   A linearly polarized femtosecond laser emitted from the femtosecond laser oscillator is guided into the cylinder, and the femtosecond laser is advanced in the outer diameter direction while condensing the femtosecond laser by the condensing lens and the reflection mirror in the cylinder. The inner peripheral surface of the cylindrical workpiece held by the chuck means is opposed to the outer periphery of the workpiece, and the femtosecond laser is irradiated to rotate the cylindrical workpiece to align the periodic grooves in the same direction in the inner peripheral surface. A method for machining a periodic structure on an inner circumferential surface of a cylinder.   The chuck means holding the cylindrical work is continuously or intermittently moved in the axial direction of the cylindrical work by the Z-axis driving means, and the femtosecond laser is irradiated to the inner peripheral surface of the cylindrical work by a predetermined width. The periodic structure processing method of a cylindrical inner peripheral surface according to claim 7.   The femtosecond laser heading toward the reflecting mirror is incident on a dimple processing homogenizer or a mixing processing homogenizer disposed in the cylinder and on the front side of the condenser lens. The periodic structure processing method for a cylindrical inner peripheral surface according to claim 7 or 8, wherein the periodic structure is formed.   A femtosecond laser oscillator, a cylindrical body that introduces a linearly polarized femtosecond laser from the femtosecond laser oscillator, a condenser lens that is disposed in the cylindrical body and collects the linearly polarized femtosecond laser, and A reflection mirror that is disposed on the distal end side and refracts the femtosecond laser in the outer diameter direction; chuck means that grips the cylindrical workpiece at a predetermined position; and a work rotation drive unit that rotationally drives the chuck means. An apparatus for processing a periodic structure on a cylindrical inner peripheral surface.   The periodic structure processing apparatus for an inner peripheral surface of a cylinder according to claim 10, further comprising a Z-axis driving means for moving the cylindrical workpiece held by the chuck means back and forth in the axial direction.   The periodic structure processing apparatus for an inner peripheral surface of a cylinder according to claim 10 or 11, wherein a dimple processing homogenizer or a mixing processing homogenizer is disposed in the cylindrical body on the front side of the condenser lens.