JP2017119304A - Laser beam machining apparatus, laser beam machining method, and distance measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably enable measurement of a distance between a machining point and a reference position in laser peening used in combination with water flow.SOLUTION: A laser beam machining apparatus 100 includes: a laser beam source 11 for emitting a laser beam 11a; a condensing section 12 for condensing the laser beam 11a onto a member to be machined 1 being an object of surface hardening treatment; a water flow transmission section 5 for supplying water flow 5a to a machining surface of the member to be machined 1; an acoustic sensor 10 being provided at a predetermined relative position with respect to at least any of the water flow transmission section 5 and the condensing section 12 and receiving sound from the machining surface; a time width acquisition section 31 for acquiring a measurement time width from timing as a reference until the acoustic sensor 10 receives the sound; and a distance calculation section 32 calculates a distance from at least any of the water flow transmission section 5 and the condensing section 12 to the machining surface based on the measurement time width.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a laser processing apparatus, a laser processing method, and a distance measurement method.

  In plants requiring high safety, such as nuclear power plants, during periodic inspections, automatic equipment is used to access equipment that is difficult for humans to access, such as in-furnace equipment, and various maintenance such as inspection, surface modification, and repair. Construction has been done. Among them, as a countermeasure against SCC (Stress Corrosion Cracking) caused by tensile stress remaining in the welded portion, a laser peening method and apparatus capable of effectively preventing the occurrence have been developed.

  FIG. 48 is a conceptual diagram showing the principle of laser peening. When the laser beam 11a having a pulse width of about several ns is condensed on a spot having a diameter of about 1 mm by the condensing unit 12 and is irradiated onto the workpiece 1, the surface of the workpiece 1 absorbs energy and turns into plasma. When the periphery of the plasma 4 is covered with a liquid 6 that is transparent to the wavelength of the laser beam, the expansion of the plasma 4 is hindered, and the internal pressure of the plasma 4 reaches about several GPa, and the workpiece 1 is impacted. Add. At that time, a strong shock wave 7 is generated in the workpiece 1 and the liquid 6. The shock wave 7 propagates inside the workpiece 1 and causes plastic deformation, thereby changing the residual stress in the region of the machining point 2 to a compressed state.

  Laser peening is less dependent on material strength of work hardening than other peening techniques such as shot peening, water jet peening, ultrasonic shot peening, etc., and is about 1 mm from the surface of the workpiece 1 in the thickness direction. It extends to. In addition, since there is no reaction force during processing, it is easy to reduce the size of the processing apparatus, and the processability to the narrow portion is excellent. For example, a laser processing apparatus and a laser processing method that can be applied to an object having a small tube inner diameter have been developed.

  In general, in laser peening, it is necessary to place the workpiece 1 in the liquid 6 or to apply a coating in order to obtain a plasma stress confinement effect. For this reason, limitation of construction environment and complicated procedures have been problems, but technologies that enable laser peening even in an air environment have been developed. This is to achieve local water-tightening of the optical path and the processing point by injecting a water flow into the workpiece 1 and transmitting a laser therein, which has the potential to greatly expand the application range of laser peening. doing.

Japanese Patent No. 4697699 Japanese Patent Laying-Open No. 2005-300192 Japanese Patent No. 4868729

  In order to obtain a sufficient stress improvement effect by laser peening, in order to generate a shock wave 7 having a necessary energy when the workpiece 1 is irradiated with the laser beam 11a, the energy density on the irradiated surface is ensured. Therefore, it is necessary to control the spot diameter within a certain range so that the spot diameter does not become too large. This is common in the case of performing in liquid, in the case of painting, and in the case of water jet.

  The spot diameter of the laser beam 11a varies depending on the distance from the condensing unit 12 provided in the laser irradiation head to the workpiece 1. Therefore, it is necessary to control this distance to be a predetermined value. For this purpose, the distance between the position irradiated with the laser beam 11a, that is, the surface of the member 1 to be processed, and a reference position (for example, a condensing unit, an optical head end surface, or a nozzle tip) is accurately measured. There is a need.

  As the distance measurement, for example, by measuring the shock wave generated at the processing point with an acoustic sensor, the trigger obtained from the laser light source is the start point, and the time width when the shock wave reaches the end point is used as the processing point. A technique for calculating the distance of an acoustic sensor has been proposed.

  However, this technique is based on the premise that a continuous liquid is filled at least from the processing point to the acoustic sensor. In laser peening combined with water flow, the processing point existing in the liquid is used as a sound source, the shock wave propagates in the liquid, passes through the gas-liquid interface from the liquid to the air, propagates in the air, and reaches the acoustic sensor. Follow the path to do.

  The speed of sound differs greatly between the liquid and air, and the thickness of the liquid film that occurs at the processing point fluctuates in the water flow. Further, when liquid splash generated by a water flow adheres to the acoustic sensor, it may appear as a measurement distance error. Further, as a general measurement technique, there are a laser distance meter, a stereo view of a camera, and the like. However, since an optical path is blocked or distorted by splashing, measurement is practically impossible. Thus, in the case of laser peening combined with water flow, the distance between the processing point and the acoustic sensor cannot be measured by simple shock wave time measurement or optical means.

  Therefore, an object of the embodiment of the present invention is to make it possible to stably measure a distance between a processing point and a reference position even in laser peening combined with a water flow, for example.

  In order to achieve the above object, a laser processing apparatus according to this embodiment includes a laser light source that emits laser light, a condensing unit that condenses the laser light on a workpiece to be surface-cured, and A water flow transmission unit that supplies a water flow to the processing surface of the workpiece, and an acoustic wave that is provided at a predetermined relative position with respect to at least one of the water flow transmission unit and the light collecting unit and receives sound from the processing surface At least one of the sensor, a time width acquisition unit that acquires a measurement time width from the reference timing to when the acoustic sensor receives sound, and the water flow transmission unit and the light collection unit based on the measurement time width A distance calculation unit for calculating a distance from the surface to the processing surface.

  In addition, the laser processing method according to the present embodiment obtains a reference measurement time width from when laser light irradiation is performed at a known reference distance by a laser light irradiation apparatus until reception of sound generated by the laser light irradiation is received. The laser beam irradiation is performed by the laser beam irradiation apparatus by setting any one of the measurement step and a plurality of the workpiece target sites as the irradiation target site, and the laser beam irradiation from the laser beam irradiation. The laser beam irradiation based on the irradiation step of acquiring the measurement time width until receiving the sound generated by the step, the reference distance, and the difference between the measurement time width acquired in the irradiation step and the reference measurement time width A distance calculating step of calculating a distance between the apparatus and the irradiation target portion.

  Further, in the distance measurement method according to the present embodiment, the time width acquisition unit acquires a reference measurement time width for a known reference distance, and the time width acquisition unit performs laser light irradiation with a laser light irradiation device. The laser light irradiation device and the irradiation point of the laser light irradiation based on the irradiation step for acquiring the measurement time width, the reference distance, and the difference between the measurement time width acquired in the irradiation step and the reference measurement time width And a distance calculating step for calculating a distance between and.

  According to the embodiment of the present invention, it is possible to stably measure the distance between the machining point and the reference position even in laser peening combined with a water flow, for example.

It is a block diagram which shows the structure of the laser processing apparatus which concerns on 1st Embodiment. It is a notional elevation sectional view showing composition around a water current transmission part of a laser processing device concerning a 1st embodiment. It is a notional standing sectional view showing the composition including the condensing distance adjustment part of the laser processing device concerning a 1st embodiment. It is a notional standing sectional view showing the composition including the movement drive part of the laser processing device concerning a 1st embodiment. It is a conceptual elevation sectional view showing the composition including the modification of the movement drive part of the laser processing device concerning a 1st embodiment. It is a wave form diagram which shows the received waveform image of the acoustic sensor of the laser processing apparatus which concerns on 1st Embodiment. It is a conceptual graph explaining the setting of the reference point of time width calculation, (a) shows an unpreferable example, (b) shows a preferable example. It is a conceptual graph explaining calculation of the propagation time of a shock wave in the laser processing apparatus concerning a 1st embodiment. It is a conceptual diagram explaining calculation of the propagation time of the shock wave in the laser processing apparatus which concerns on 1st Embodiment. It is a block diagram which shows the procedure of the laser processing method which concerns on 1st Embodiment. It is a wave form diagram which shows the receiving waveform image of the acoustic sensor which shows the case where the distance with the process point of a to-be-processed member changes, (a) is a signal before a change, (b) is a signal after a change. It is a notional elevation sectional view showing the composition of the laser processing device concerning a 2nd embodiment. It is a notional elevation sectional view showing the composition of the laser processing device concerning a 3rd embodiment. It is a notional elevation sectional view for explaining measurement of construction distance by a laser processing device concerning a 3rd embodiment. It is a notional elevation sectional view showing the composition of the laser processing device concerning a 4th embodiment. It is a notional elevation sectional view showing the composition of the modification of the laser processing device concerning a 4th embodiment. In the laser processing apparatus which concerns on 5th Embodiment, it is a conceptual diagram which shows the structure in case an acoustic sensor has an acoustic sensing part by which surface treatment with low wettability was given, (a) is a top view, (b) Is a front view. In the laser processing apparatus which concerns on 5th Embodiment, it is a conceptual diagram which shows the structure in case an acoustic sensor has an acoustic sensing part by which surface treatment with high wettability was given to the outer surface, (a) is a top view, (B) is a front view. In the laser processing apparatus which concerns on 5th Embodiment, an acoustic sensor is a conceptual diagram which shows the structure which has an acoustic sensing part by which the geometric shape of the convex part was formed in the outer surface as a whole, (a) is a top view, (B) is a front view. In the laser processing apparatus which concerns on 5th Embodiment, an acoustic sensor is a conceptual diagram which shows the structure which has an acoustic sensing part by which the geometric shape containing a some convex part was formed in the outer surface, (a) is a top view (B) is a front view. In the laser processing apparatus which concerns on 5th Embodiment, an acoustic sensor is a conceptual diagram which shows the structure which has an acoustic sensing part by which the geometric shape of the recessed part was formed in the outer surface as a whole, (a) is a top view, ( b) is a front view. In the laser processing apparatus which concerns on 5th Embodiment, an acoustic sensor is a conceptual diagram which shows the structure which has an acoustic sensing part by which the geometric shape of several recessed part was formed in the outer surface, (a) is a top view, ( b) is a front view. It is a block diagram which shows the structure of the laser processing apparatus which concerns on 6th Embodiment. It is a longitudinal cross-sectional view which shows the structure of the acoustic sensor of the laser processing apparatus which concerns on 6th Embodiment. It is a graph explaining the effect of the laser processing apparatus which concerns on 6th Embodiment. It is a notional elevation sectional view showing the composition of the laser processing device concerning a 7th embodiment. It is an elevation sectional view explaining the 1st modification of an attachment state of an acoustic sensor in a laser processing apparatus concerning a 7th embodiment. It is an elevation sectional view explaining the 2nd modification of the attachment state of the acoustic sensor in the laser processing apparatus concerning a 7th embodiment. It is a sectional elevation explaining the 1st transmission path of the sound in the laser processing apparatus concerning a 7th embodiment. It is a sectional elevation explaining the 2nd transmission path of the sound in the laser processing apparatus concerning a 7th embodiment. It is a wave form diagram which shows the received waveform image of the acoustic sensor of the laser processing apparatus which concerns on 7th Embodiment. It is XXXII-XXXII arrow sectional drawing of FIG. 33 which shows the installation state at the time of making an acoustic shoe into the cylinder shape centering on a horizontal direction. It is a plane sectional view which shows the installation state at the time of making an acoustic shoe into a cylindrical shape. It is XXXIV-XXXIV arrow sectional drawing of FIG. 35 which shows the installation state at the time of making an acoustic shoe into flat plate shape. It is a plane sectional view which shows the installation state at the time of making an acoustic shoe into flat plate shape. It is XXXVI-XXXVI arrow sectional drawing of FIG. 37 which shows the installation state at the time of making an acoustic shoe into a taper shape. It is a plane sectional view which shows the installation state at the time of making an acoustic shoe into a taper shape. It is XXXVIII-XXXVIII arrow sectional drawing of FIG. 39 which shows the installation state at the time of making an acoustic shoe into cone shape. It is a plane sectional view which shows the installation state at the time of making an acoustic shoe into cone shape. It is XL-XL arrow sectional drawing of FIG. 41 which shows the installation state at the time of making an acoustic shoe into a rotation semi-ellipsoid shape. It is a cross-sectional view showing an installation state when the acoustic shoe has a rotating semi-ellipsoidal shape. It is XLII-XLII arrow sectional drawing of FIG. 43 which shows the installation state at the time of using the acoustic sensor which inclines. It is a plane sectional view which shows the installation state at the time of using the acoustic shoe which inclines. It is a notional elevation sectional view showing the composition of the laser processing device concerning an 8th embodiment. It is a notional standing sectional view showing the composition of the modification of the laser processing device concerning an 8th embodiment. It is a conceptual perspective view which shows the structure of the commutator of the laser processing apparatus which concerns on 8th Embodiment. It is a notional elevation sectional view showing the composition of another modification of the laser processing device concerning an 8th embodiment. It is explanatory drawing which shows the principle of the conventional laser peening.

  Hereinafter, a laser processing apparatus, a laser processing method, and a distance measurement method according to embodiments of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of the laser processing apparatus according to the first embodiment. A laser processing apparatus (laser light irradiation apparatus) 100 performs surface hardening treatment by irradiating a workpiece 1 in a gas atmosphere such as an air atmosphere with a laser. Laser irradiation is performed by selecting any one of a plurality of construction target locations defined for the workpiece 1 that is a construction target as the irradiation target location. A laser processing device (laser light irradiation device) 100 includes a laser light source 11, a water flow source 21, a water flow transmission unit 5, a calculation unit 30, a control unit 40, an acoustic sensor 10, a light collection distance adjustment unit 50 (FIG. 3), and a movement. It has the drive part 90 (FIG. 4, FIG. 5). A condenser 12 for converging the laser beam 11 a applied to the workpiece 1 is attached to the water flow transmitter 5.

  The laser light source 11 emits laser light. Examples of the laser light include Nd: YAG laser, CO2 laser, Er: YAG laser, titanium sapphire laser, alexandrite laser, ruby laser, fiber laser, dye (die) laser, and excimer laser, and other lasers. Even if it is a light source, another laser may be used as long as it can give a necessary energy to a workpiece. The laser light source 11 may be either a continuous wave generation method or a pulse wave generation method. Moreover, you may supply to the same location of the to-be-processed member 1 from multiple units | sets.

  The condensing unit 12 condenses the laser beam at the processing point 2 on the processing surface of the workpiece 1. The condensing unit 12 may be, for example, a single convex lens, or a combination of two or more convex lenses or other lenses. The convex lens may be a plano-convex lens, a biconvex lens, or an aspheric lens. Alternatively, the other lens may be a plano-concave lens, a biconcave lens, a cylindrical lens, or the like. Or the condensing part 12 may use a concave mirror.

  As means for transmitting the laser beam to the condensing unit 12, spatial transmission using a mirror or a lens, fiber transmission using a fiber, or a combination thereof may be considered. A homogenizer, an aperture, or the like may be used to make the profile of the laser beam uniform. For adjusting the intensity, a λ / 2 wavelength plate, a polarizer, a beam splitter, a half mirror, or the like may be used. Each of the optical system elements described above may be coated to change the reflectance and transmittance according to the wavelength of the laser.

  The water flow source 21 supplies water to form a water flow for generating a partial submerged environment on the surface of the workpiece 1 while the workpiece 1 is irradiated with the laser beam 11a. The water flow source 21 may be, for example, a system that uses an on / off valve from a water pressure source. Or the system which moves a piston with the supply source by a piston may be sufficient.

  The water flow transmission part 5 is cylindrical, the upstream side is connected to the water flow source 21, and the outlet side is open. The water flow transmission unit 5 guides the water flow to the workpiece 1 without entraining bubbles, and ejects liquid onto the workpiece 1. Further, the water flow transmission unit 5 is provided with a light collecting unit 12, but the light collecting unit 12 is located upstream from the outlet by a predetermined distance or more so as not to be affected by the water flow at the outlet of the water flow transmission unit 5. It is attached.

  As the liquid used here, a liquid that does not ignite in the air and does not hinder the propagation of laser light, for example, an aqueous solution such as pure water, city water, or boric acid water can be used. At this time, since liquids that are transparent to all wavelengths are limited, it is necessary to select each of them in consideration of the compatibility of the wavelengths of the liquid and the laser beam, that is, the high transmittance. Even if the attenuation factor is high to some extent, any combination can be used as long as a sufficient strength is obtained after propagating a predetermined distance. In addition, by setting an inert gas atmosphere around the water flow, ignitable liquids such as alcohols and oils can be used in the air.

  Here, as a representative example, it is assumed that the atmosphere is air and the liquid is general city water. Here, the case where the laser beam and the water flow are coaxial is shown, but if a partial water film is obtained at the processing point 2 of the workpiece 1, the water flow and the laser beam may be on different axes. Here, the processing point 2 refers to a portion to be processed on the surface of the workpiece 1 every time laser light is irradiated.

  The acoustic sensor 10 is fixed to, for example, the water flow transmission unit 5 so that the relative positional relationship with the water flow transmission unit 5 is constant, and the shock wave generated at the processing point 2 of the workpiece 1 is a sound wave (acoustic). ) Configured to be detectable. The acoustic sensor 10 is attached in a direction in which a portion to be detected by receiving a sound wave, that is, the acoustic sensing unit 10a faces the workpiece 1 side. The output of the acoustic sensor 10 is input to the calculation unit 30.

  The acoustic sensor 10 is an aerial ultrasonic measurement probe using a general piezoelectric element. However, it is not limited to this. For example, any sensor that can receive a shock wave band to be measured, such as a waterproof speaker or a vibration meter that irradiates a diaphragm surface with a laser, can be used as the acoustic sensor 10. In addition, when the relative position with respect to the water flow transmission part 5 can be set to the predetermined position determined beforehand, it is also possible to fix the acoustic sensor 10 to members other than the water flow transmission part 5.

  The calculation unit 30 includes a time width acquisition unit 31 and a distance calculation unit 32.

  The time width acquisition unit 31 acquires a time width Tw from a certain reference time Ti to a time Te at which the shock wave generated at the processing point 2 of the workpiece 1 reaches the acoustic sensor 10. The time width acquisition unit 31 has means for digitizing an analog signal obtained from the acoustic sensor 10, and generally includes a measuring instrument called a digital oscilloscope, a personal computer incorporating an AD converter, A personal computer connected to a similar dedicated device, or a combination thereof may be used. The time width acquisition unit 31 is connected to the laser light source 11 that oscillates the laser light 11a and the water flow source 21 that generates the water pressure necessary for forming the water flow, and can also exchange signals with each other.

The distance calculation unit 32 calculates the distance between the processing point 2 and the acoustic sensor 10 based on the propagation time measured by the time width acquisition unit 31. Here, the representative point of the laser processing device (laser irradiation device) 100, for example, the tip of the water flow transmitter 5, the distance between the processing point 2 of interest, displayed in construction distance D ₀ is called a construction distance I will do it. Further, it is assumed that to display in propagation distance D _p is called the distance between the propagation distance between the sound detector 10a of the machining point 2 and the acoustic sensor 10. Further, it is assumed that to display the distance between the condensing unit 12 and the processing point 2 by the condenser distance and called condensing distance D _f. By measuring or calculating the propagation distance _Dp and the condensing distance _Df , the distance (construction distance D ₀ ) between the laser processing apparatus 100 that is a laser light irradiation apparatus and the processing point 2 can be obtained.

  The control unit 40 exchanges signals with the laser light source 11, the water flow source 21, the water flow transmission unit 5, the calculation unit 30, the condensing distance adjustment unit 50 (see FIG. 3), and the movement drive unit 90 (see FIG. 4). The laser light source 11, the water flow source 21, the calculation unit 30, the condensing distance adjustment unit 50, and the movement drive unit 90 each independently adjust a set value such as an output or ON / OFF. You can also.

  FIG. 2 is a conceptual elevational sectional view showing a configuration around the water flow transmission unit. The workpiece 1 is vertically above the water flow transmission unit 5, and the water flow 5a is directed vertically upward. In addition, although embodiment shows the case where the to-be-processed member 1 exists in the vertically upper direction of the water flow transmission part 5, it is not limited to this. That is, the member 1 to be processed may be in the lateral direction of the water flow transmission unit 5 or may be vertically downward.

In the water flow 5a from the water flow transmission unit 5 toward the workpiece 1, the laser beam 11a is also directed in the same direction. The laser beam 11 a is converged toward the workpiece 1 by the light collecting unit 12 provided in the water flow transmission unit 5. In order to set the irradiation density of the laser beam 11a at the processing point 2 to a predetermined value or more, the condensing distance D _f between the position of the condensing unit 12 and the processing point 2 is F−ΔF <D _f <F + ΔF. It is necessary to satisfy the condition, that is, within a predetermined range. However, F is a focal length and ΔF is a predetermined width. In addition, in order to arrange _| position the condensing part 12 to an appropriate position, the condensing distance _Df is comprised by the condensing distance adjustment part 50 mentioned later so that adjustment is possible.

Therefore, the condensing distance D _f itself, or it is necessary to measure the available calculating a focusing distance D _f distance. The acoustic sensor 10 detects a shock wave generated when the laser beam 11a reaches the processing point 2.

FIG. 3 is a conceptual elevational sectional view showing a configuration including a condensing distance adjusting unit. The condensing distance adjusting unit 50 adjusts the position of the condensing unit 12 in the optical axis direction. In order to maintain the distance between the light condensing unit 12 and the member 1 to be processed within an appropriate range, the condensing distance adjusting unit 50 can be used to adjust the distance. At this time, it may be predicted to adjust the distance from the positional relationship of the workpiece 1 in the shape and the condensing portion 12 measured in advance, by feeding back the results of the actually measured propagation distance D _p and the condensing distance D _f You may adjust sequentially so that each may become the optimal distance.

  FIG. 4 is a conceptual elevational sectional view showing a configuration including a moving drive unit. The movement drive unit 90 includes a restraint unit 91, an arm 92, a joint 93, and a power unit 95. The power unit 95 is fixedly supported from the outside. The angle of the joint 93 is changed by the power unit 95. For this reason, the direction of the arm 92 changes and the condensing part 12 and the acoustic sensor 10 attached to the water flow transmission part 5 couple | bonded by the restraint part 91 move. As a result, the distance between the water flow transmission unit 5, the acoustic sensor 10 and the light collecting unit 12, and the workpiece 1 is changed.

  Moreover, the movement drive part 90 moves the water flow transmission part 5, the condensing part 12 attached to this, the acoustic sensor 10 grade | etc., According to the position of the process point 2 which should be moved sequentially on the process surface of the to-be-processed member 1. Let

  FIG. 5 is a conceptual vertical sectional view showing a configuration of a modified example of the movement drive unit. In the case of this modification, the power unit 95 of the movement drive unit 90 is fixed to the workpiece 1. Also in this modification, the movement drive unit 90 changes the distance between the water flow transmission unit 5 and the acoustic sensor 10 and the workpiece 1 and the position corresponding to the movement of the processing point 2. In terms of power, a mechanism may be used in which the distance between the water flow transmission unit 5 and the acoustic sensor 10 and the workpiece 1 is adjusted manually by the movement drive unit 90.

  Next, the operation of the laser processing apparatus 100 according to this embodiment configured as described above will be described.

  The laser beam 11a applied to the processing point 2 of the workpiece 1 causes an ablation phenomenon, that is, a phenomenon in which constituent materials on the surface of the workpiece 1 are explosively released with the generation of plasma. As a result, a shock wave having the processing point 2 as a sound source is generated. The shock wave acts on the machining point 2 to apply a compressive stress to the machining point 2.

  The generated shock wave first propagates in the liquid. Further, the light is transmitted from the liquid through the gas-liquid interface to the air, propagates through the air, and is received by the acoustic sensor 10 when reaching the acoustic sensor 10.

  FIG. 6 is a waveform diagram showing a received waveform image of the acoustic sensor. The horizontal axis is time, and the starting point is 0 for each oscillation period. The vertical axis represents the voltage value captured by the acoustic sensor as the received waveform. Ti in the figure is a timing that serves as a reference for the time width.

  FIG. 7 is a conceptual graph for explaining the setting of a reference point for time width calculation, where (a) shows an unfavorable example and (b) shows a preferred example. The horizontal axis in FIG. 7 represents the entire flow of time, and the vertical axis represents the voltage value as in FIG. A plurality of broken lines indicate the start timing of each transmission. Ti indicated by a solid line indicates a reference timing. In FIG. 7A, the relationship between the timing indicated by the broken line and the timing of Ti indicated by the solid line is not constant. In FIG. 7B, the relationship between the timing indicated by the broken line and the timing of Ti indicated by the solid line is constant, and the reference timing Ti is desirably a signal that satisfies such a condition.

  For example, in the case of a laser of 10 Hz, there is Ti timing at least once in one period of 100 ms, and if the laser oscillation time is 0 ms, Ti is selected between 0 ms and less than 100 ms, and It is desirable to set a fixed value. As a signal source for obtaining a Ti signal, a Q switch timing from the laser light source 11, a setting signal estimated from the pulse repetition frequency of the laser light 11a, and the like can be used.

  Te in FIG. 6 is the arrival time of the shock wave. The method of determining the time is, for example, threshold judgment that adopts the time when the signal intensity exceeds a certain threshold, peak judgment that adopts the peak time of a certain waveform, zero cross method that adopts the time that intersects with the zero point, standard It can be obtained by using a method of taking a cross-correlation with the waveform to be. FIG. 6 shows a case where peak determination is used.

  The time width Tw is a time width obtained by subtracting the time Ti from the time Te. For example, if Ti is adjusted to the laser emission timing, the obtained Tw substantially represents the time from when the laser beam acts on the machining point until the shock wave reaches the acoustic sensor 10. That is, the propagation time of the shock wave. Here, for example, the timing at which a command signal to the laser light source 11 is issued can be used as the light emission timing.

  FIG. 8 is a conceptual graph illustrating calculation of the propagation time of shock waves. FIG. 9 is a conceptual diagram illustrating calculation of the propagation time of the shock wave. Here, Ti will be described below assuming that it is a timing of laser emission.

As shown in FIG. 8, the time width Tw is a total of a time _{TL in} which the shock wave propagates in the liquid and a time _{TG in} which the shock wave goes out in the air and propagates in the air. Empirically, it is considered that the signal that the acoustic sensor 10 detects significantly as a shock wave mainly originates from the processing point 2 and propagates through the air after passing through the liquid in the shortest time. In other words, in FIG. 9, the shock wave generated from the processing point 2, that is, the sound wave generated by the shock propagates the distance R in the water column, then propagates the distance L in the air, and reaches the acoustic sensor 10. It is considered that this appears as the propagation time in FIG.

Therefore, the propagation time _TL in the liquid is given by the following equation (1). However, V _L is the propagation speed of the sound wave in the liquid.
T _L = R / V _L (1)

As a result, _{T G} is determined by the following equation (2), the propagation distance _{D p} can be calculated by the equation (3). However, V _G is the propagation speed of the sound wave in the air.
T _G = T _W −T _L (2)
_{D p = L + R = T} G · V G + R ... (3)

Since the relative positional relationship between the acoustic sensor 10 and the water flow transmission unit 5 and the light collecting unit 12 is known, if the propagation distance D _p is known in this way, the processing point 2 and the light collecting unit 12 It is possible to calculate the condensing distance D _f that is the distance between them or the construction distance D ₀ that is the distance between the processing point 2 and the representative part of the laser processing apparatus 100.

  FIG. 10 is a block diagram illustrating a procedure of the laser processing method according to the first embodiment.

Positional relationship between the machining point 2 and the laser processing apparatus 100 in the case of known, the propagation distance D _p between the reference distance. Incidentally, the reference distance propagation distance D rather than _p, or the distance of the condensing distance D _f or construction distance D _0. First, a reference measurement time width is acquired for this reference distance (step S01). Next, the laser beam 11a is irradiated to the processing point 2 which is the irradiation target portion of the workpiece 1 (step S02). Get the propagation time of the shock wave generated every laser beam irradiation, and calculates the propagation distance D _p (step S03).

Next, it is determined from the propagation distance D _p, calculates the condensing distance D _f and construction distance D ₀ to be determined, whether the condensing distance D _f is a proper range (step S04). In the case where the condensing distance D _f is not determined to be appropriate range (step S04 NO), using a condensing distance adjustment unit 50 modifies the condensing distance D _f (step S05), on the Step S02 and subsequent steps are repeated. When it determines with it being an appropriate range (step S04 YES), it determines with construction having been completed about the process point 2 which is an irradiation object location (completed construction). And it is determined whether all the parts of the some construction object location set to the to-be-processed member 1 have been constructed (step S06). If it is determined that the construction has been completed (step S06 YES), the laser processing is terminated.

  If it is determined that the construction has not been completed (NO in step S06), any one of the plurality of construction target locations set on the workpiece 1 that has not been determined to be constructed is set as an irradiation target location. That is, the processing point 2 is moved to a place where construction has not been completed (step S07), and then step S02 and subsequent steps are repeated.

FIG. 11 is a waveform diagram showing a received waveform image of the acoustic sensor when the distance from the machining point of the workpiece changes, where (a) is the signal before the change and (b) is the signal after the change. is there. Consider a case where the distance between the laser processing apparatus 100 and the processing point 2 of the workpiece 1, that is, the construction distance D ₀ is increased by moving the processing point 2.

In this case, it is assumed that the arrival time of the shock wave to the acoustic sensor 10 is delayed by dTw as compared with the reference time width Twi in the case of FIG. 11A as a reference, that is, the propagation time is increased by dTw. Since the diameter R of the water column hardly changes even if the construction distance changes, the increase dTw in the propagation time can be regarded as a time change due to a change in pure air distance. Therefore, the value obtained by multiplying the propagation velocity _{V G} of a sound wave aerial to dTw is, increment dD next to propagation distance, propagation distance _{D p} is the the reference distance _{D p0} plus the increment dD _(D p0 + dD) Calculated.

It is desirable that the variation in the diameter R of the water column can be controlled so as to be smaller than the measurement resolution of the propagation distance D _p , the condensing distance D _f, and the construction distance D ₀ to be obtained. Specifically, it is reduced by suppressing the pulsation at the water flow source 21 and suppressing the generation of the swirling flow in the path leading to the water flow transmission unit 5.

  As described above, the laser peening combined with the water flow by the laser processing apparatus in the present embodiment can stably measure the distance between the processing point and the reference position.

[Second Embodiment]
FIG. 12 is a conceptual sectional elevation view showing the configuration of the laser processing apparatus according to the second embodiment. This embodiment is a modification of the first embodiment. The laser processing apparatus 100 in the present embodiment includes a light detection unit 13.

Even with a certain period of repetition, the laser oscillation may have jitter of about several μs, that is, fluctuations and disturbances. By detecting the actual light emission timing using the photodetector 13 and setting the timing of the detection signal to Ti, it is possible to improve the measurement accuracy of the propagation distance D _{p and} thus the condensing distance D _f .

[Third Embodiment]
FIG. 13 is a conceptual sectional elevation view showing the configuration of the laser processing apparatus according to the third embodiment. This embodiment is a modification of the first embodiment. The laser processing apparatus 100 in this embodiment has two acoustic sensors 15a and 15b. The number of acoustic sensors may be three or more.

  FIG. 14 is a conceptual sectional elevation view for explaining the measurement of the construction distance. Now, a shock wave is emitted from the processing point 2 and reaches the two acoustic sensors 15a and 15b. The distance between the processing point 2 calculated from the propagation time to the acoustic sensor 15a and the receiving portion of the acoustic sensor 15a is D1. It can be estimated from this that the processing point 2 exists on the spherical surface having the radius D1 from the receiving portion of the acoustic sensor 15a. Similarly, the distance between the processing point 2 calculated from the propagation time to the acoustic sensor 15b and the receiving portion of the acoustic sensor 15b is D2. It can be estimated from this that the processing point 2 exists on the spherical surface having the radius D2 from the receiving portion of the acoustic sensor 15b.

  As a result, it is estimated that the processing point 2 exists on the intersection line of the spherical surface having the radius D1 from the receiving portion of the acoustic sensor 15a and the spherical surface having the radius D2 from the receiving portion of the acoustic sensor 15b. There are an infinite number of points on this intersection line, but the point at which this intersection line contacts the surface of the workpiece 1 can be estimated as the machining point 2. If the intersection line and the surface of the workpiece 1 are not in contact with each other but are separated, the closest point can be estimated as the machining point 2. Alternatively, when the intersection line and the surface of the workpiece 1 intersect, the intermediate point between the two points where the intersection line penetrates the workpiece 1 can be estimated as the machining point 2.

If the angle of the water flow 5a has changed unexpectedly, to calculate a focusing distance D _f and construction distance D ₀ is based on the propagation distance D _p that typically calculated, resulting in erroneous results. By obtaining the position of the processing point 2 from the results of measurement using a plurality of acoustic sensors, it is possible to calculate the correct condensing distance D _f and the construction distance D ₀ in the three-dimensional space.

  If there are three acoustic sensors 10, only one intersection is determined in the three-dimensional space, and the position of the processing point 2 can be specified with high accuracy.

[Fourth Embodiment]
FIG. 15 is a conceptual sectional elevation view showing the configuration of the laser processing apparatus according to the fourth embodiment. This embodiment is a modification of the first embodiment. The laser processing apparatus 100 according to the fourth embodiment includes a spray adhesion preventing unit 60 that prevents splashing of the acoustic sensor 10 from the workpiece 1 from being applied to the acoustic sensing unit 10a of the acoustic sensor 10.

  Specifically, as shown in FIG. 15, the spray adhesion preventing unit 60 can use a protective cover 61. The protective cover 61 is formed so as to cover the acoustic sensing unit 10a of the acoustic sensor 10 in the direction in which the splash of water splashes on the acoustic sensor 10.

  FIG. 16 is a conceptual vertical sectional view showing a configuration of a modified example of the laser processing apparatus according to the fourth embodiment. In the present modification, the laser processing apparatus 100 includes an air blower 62 as the splash adhesion preventing unit 60. The air blower 62 is directed in the direction in which the splash of water splashes on the acoustic sensor 10, and blows off the splash of splashing to prevent the spray from adhering to the acoustic sensing unit 10 a of the acoustic sensor 10.

  If water droplets adhere to the acoustic sensing unit 10a of the acoustic sensor 10 and a liquid film is generated on the surface of the acoustic sensing unit 10a, it causes a time delay. Moreover, if the thickness of the liquid film changes, the sensitivity changes. In the laser processing apparatus 100 according to the fourth embodiment or its modification having the above-described configuration, the adhesion of the spray to the acoustic sensing unit 10a is prevented, so that a problem such as a change in sensitivity due to the spray does not occur.

[Fifth Embodiment]
This embodiment is a modification of the first embodiment. The acoustic sensor 10 according to the fifth embodiment includes a water exposure effect mitigating unit 70. The water impact mitigating unit 70 is provided in order to prevent a change in sensitivity of the acoustic sensor 10 due to splashing of the water flow 5 a that collides with the workpiece 1 on the acoustic sensing unit of the acoustic sensor 10.

  Hereinafter, specific examples of the flooded effect mitigating unit 70 will be described. Broadly speaking, there are a case where the surface state of the acoustic sensing unit is processed and a case where a special geometry is added to the acoustic sensing unit. . In addition, you may combine both the process of the surface state of an acoustic sensing part, and addition of special geometry.

  FIG. 17 is a conceptual diagram illustrating a configuration in a case where the acoustic sensor 10 includes an acoustic sensing unit 10b subjected to a surface treatment with low wettability, where (a) is a plan view and (b) is a front view. . As surface treatment with low wettability, for example, a method of coating the surface with a highly hydrophobic material (oil, etc.) or a surface pattern with high hydrophobicity (pattern with a lot of protrusions such as the lotus leaf surface) is processed. You can use the method of applying. For this reason, the surface of the acoustic sensing unit 10b is not covered with the water 5b due to splashing, and problems such as a change in sensitivity do not occur.

  FIG. 18 is a conceptual diagram illustrating a configuration in a case where the acoustic sensor 10 includes an acoustic sensing unit 10c having a surface treatment with high wettability on the outer surface, where (a) is a plan view and (b) is a front view. FIG. Improvements in wettability include, for example, a method of coating a surface with a highly hydrophilic material (titanium oxide, etc.), surface pattern processing with high hydrophobicity, or pattern processing with high hydrophobicity and hydrophilicity. The method can be used. For this reason, even if the water 5b resulting from the splash arrives at the acoustic sensing unit 10c, the thickness of the liquid film is not changed by the hydrophilic coating, so the surface of the acoustic sensing unit 10c is stably covered with the water 5b and a liquid film is generated. Thus, even if a slight time delay occurs, problems such as a change in sensitivity do not occur.

  FIG. 19 is a conceptual diagram illustrating a configuration in which the acoustic sensor 10 includes an acoustic sensing unit 10d having a convex geometric shape formed as a whole on the outer surface, where (a) is a plan view and (b) is a front view. FIG. Since the acoustic sensing unit 10d is formed in a convex shape as a whole, it is formed so that water 5b does not remain even when water splashes on the surface of the acoustic sensing unit 10d. For this reason, problems such as a change in sensitivity do not occur.

  FIG. 20 is a conceptual diagram illustrating a configuration in which the acoustic sensor 10 includes an acoustic sensing unit 10e in which a geometric shape including a plurality of convex portions is formed on the outer surface, where (a) is a plan view and (b) is a plan view. It is a front view. Since the acoustic sensing unit 10e is formed in a convex shape at a plurality of locations, even if water splashes on the surface of the acoustic sensing unit 10e, the remaining water 5b is small, and a change in sensitivity or the like is suppressed to a small level.

  FIG. 21 is a conceptual diagram illustrating a configuration in which the acoustic sensor 10 includes an acoustic sensing unit 10f in which a concave geometric shape is formed as a whole on the outer surface, where (a) is a plan view and (b) is a front view. It is. Since the acoustic sensing unit 10f is formed in a concave shape as a whole, the water 5b is stably accumulated on the surface of the acoustic sensing unit 10f, so that a problem such as a change in sensitivity does not occur.

  FIG. 22 is a conceptual diagram illustrating a configuration in which the acoustic sensor 10 includes an acoustic sensing unit 10g having a plurality of concave geometric shapes formed on the outer surface, where (a) is a plan view and (b) is a front view. It is. Since the acoustic sensing unit 10g is formed in a concave shape at a plurality of locations, the water 5b is stably accumulated on the surface of the acoustic sensing unit 10g, so that a problem such as a change in sensitivity does not occur.

[Sixth Embodiment]
FIG. 23 is a block diagram showing a configuration of a laser processing apparatus according to the sixth embodiment. This embodiment is a modification of the first embodiment. The acoustic sensor 10 of the laser processing apparatus according to the present embodiment includes an external environment influence alleviating unit 80. External influences that affect the operation of the acoustic sensor 10 include mechanical vibration, acoustic noise, or electrical noise.

  The external environment influence alleviating unit 80 includes a mechanical vibration suppressing unit 80a, an acoustic noise reducing unit 80b (FIG. 24), and an electrical noise reducing unit 80c.

  The mechanical vibration suppression unit 80a is provided between the acoustic sensor 10 and the water flow transmission unit 5 to which the acoustic sensor 10 is attached. The mechanical vibration suppressing unit 80a is made of, for example, a damper material such as rubber or a spring.

  The electrical noise reduction unit 80c is a part that shields a cable that transmits a signal received by the acoustic sensor 10. In addition, reduction and suppression of electrical noise can be performed by a power supply stabilization measure having a device using a stabilized power supply or the like.

  FIG. 24 is a longitudinal sectional view showing the configuration of the acoustic sensor. The acoustic sensor 10 includes a front plate 8b and a piezoelectric vibrator 8d which are acoustic sensing units 10a, electrodes 8c and 8f sandwiching the piezoelectric vibrator 8d back and forth, and a front plate 8b which supports the piezoelectric vibrator 8d and the electrodes 8c and 8f. Has a housing 8a. The acoustic sensor 10 is provided with an acoustic noise reduction unit 80b between the piezoelectric vibrator 8d and the electrodes 8c and 8f and the housing 8a. The acoustic noise reduction unit 80b may be provided outside the acoustic sensor 10 also serving as the mechanical vibration suppression unit 80a.

  As for acoustic noise, there is a method in which a band other than a desired frequency is cut off and a frequency band of the acoustic sensor is narrowed by attaching a damper inside or outside the acoustic sensor.

  Further, as noise removal, noise that is not related to the shock wave can be reduced by filtering the acoustic signal in the signal circuit from the acoustic sensor 10 or the arithmetic unit 30. This filtering includes a band pass filter, a high pass filter, a low pass filter, a band elimination filter, an addition average, a moving average, and the like, and imaging such as aperture synthesis using signals measured at multiple points may be performed.

  In particular, as described above, for electrical noise, it is indispensable to take measures against hardware such as stabilization of power supply and shield processing. However, since noise itself is irregular, filtering on a circuit or a program is also effective.

  FIG. 25 is a graph for explaining the effect of the laser processing apparatus according to the present embodiment. The horizontal axis is the sound frequency, and the vertical axis is the sound intensity. The shock wave indicated by the solid line is captured by the acoustic sensor 10 as a signal, but includes sound noise (noise noise) indicated by the broken line.

  In this case, the band A in FIG. 25 is the center frequency band of noise, and most of the received signals are noise noise. On the other hand, for example, when the frequency is the band B, it is a band that is close to the center frequency band of the shock wave and the intensity of noise is low. In such a case, a method can be used in which the band to be processed is narrowed in the vicinity of the band B where the intensity of the shock wave remains, avoiding the band A that is the central frequency band of noise. Since the shock wave itself has a wide band characteristic, such a narrowing is sufficiently possible.

  As described above, by reducing noise, the accuracy of the signal received by the acoustic sensor 10 can be improved, and the accuracy of time width evaluation can be improved.

[Seventh Embodiment]
FIG. 26 is a conceptual sectional elevation view showing the configuration of the laser processing apparatus according to the seventh embodiment. This embodiment is a modification of the first embodiment. Here, the distance from the tip of the water flow transmission unit 5 to the acoustic sensor surface 10a is Ds. In the laser processing apparatus according to the present embodiment, the acoustic sensor 10 is installed on the inner wall surface of the water flow transmission unit 5. Further, the sensor surface of the acoustic sensor 10 faces the inner wall surface. However, the mounting state of the acoustic sensor 10 is not limited to this, and may be, for example, a state as shown in FIGS.

  FIG. 27 is an elevational sectional view for explaining a first modified example of the acoustic sensor attached state. The acoustic sensor 10 is installed with the sensor surface facing in the direction of the water flow. FIG. 28 is an elevational sectional view for explaining a second modification of the acoustic sensor attached state. The acoustic sensor 10 is provided in a portion where a part of the inner wall surface of the water flow transmission unit 5 is cut so that a waveguide is secured.

  FIG. 29 is a longitudinal sectional view for explaining a first acoustic transmission path. FIG. 30 is a longitudinal sectional view for explaining a second transmission path of sound. The acoustic propagation path to the acoustic sensor 10 propagates in complete water as shown in FIG. 29 and to the water flow transmission unit 5 as shown in FIG. 30, and after reaching the water flow transmission unit, the inner wall of the water flow transmission unit 5 is propagated. One that propagates as a surface wave and eventually reaches the acoustic sensor 10 can be considered.

For complete water propagation time required to reach from the processing point to the acoustic sensor TW are all TL, propagation distance D _p is given by the following equation (4).
D _p = TL * VL (4)

Since Ds is known, the construction distance D ₀ can be calculated from the following equation (5).
D ₀ = D _p −Ds (5)

When propagating as a surface wave on the inner wall of the water flow transmission unit, Tw is given by Equation (6).
Tw = TL + Ts (6)

Here, Ts is the propagation time of the surface wave. Here, Ts is given by equation (7).
Ts = Ds / Vs (7)

Here, Vs is the speed of sound of the surface wave and is known together with Ds. As a result, TL is obtained by equation (8).
TL = Tw−Ts (8)

As a result, construction distance _{D 0} by the equation (9) is obtained.
D ₀ = TL / VL (9)

These makes it possible calculated construction distance D ₀ in the present embodiment.

  FIG. 31 is a waveform diagram showing a received waveform image of the acoustic sensor of the laser processing apparatus according to the seventh embodiment. The horizontal axis represents the time when the starting point is 0 for each oscillation period, and the vertical axis represents the voltage value captured by the acoustic sensor as the received waveform. After the transmission, the first shock wave arrives, and then the second shock wave arrives.

  The first shock wave corresponds to the case of propagation as a surface wave from the middle, and the second shock wave corresponds to the case of complete underwater propagation. In general, since the propagation velocity of the acoustic surface wave is larger than the propagation velocity of the underwater acoustic wave, the first shock wave arrives first.

Since the construction distance D ₀ can be calculated by using either the first shock wave or the second shock wave as described above, the case of using either the first shock wave or the second shock wave is used. May be. Alternatively, using both, the respective construction distance D ₀ obtained by both the result may also be, for example, average.

  Since the acoustic sensor 10 has directivity, it is conceivable to adjust the shape of the acoustic sensor 10 itself as a method for detecting the sound propagating underwater or the surface of the water flow transmission unit 5 with high sensitivity. However, it is not realistic to change the shape of the acoustic sensor 10 each time the installation position or orientation of the acoustic sensor 10 is changed. For this reason, an acoustic shoe is interposed between the acoustic sensor 10 and the water in the water flow transmission unit 5 to adjust the sound and propagation to the acoustic sensor 10.

  As a material for the acoustic shoe, workability is good, and in terms of acoustic propagation, it is desirable that the speed of sound is close to water and the density is lower than that of metal or the like. For example, acrylic can be used.

  32 to 43 show the installation state when the acoustic shoe is used.

  32 is a vertical sectional view taken along arrow XXXII-XXXII in FIG. 33 showing an installation state when the acoustic shoe has a cylindrical shape with the horizontal direction as an axis, and FIG. 33 is a plan sectional view. The acoustic shoe 101a has a shape in which the range is removed from the cross section of the flow path of the water flow transmission unit 5. When the acoustic shoe 101a has a cylindrical shape along the inner wall of the water flow transmission unit, it is possible to suppress disturbance to the water flow.

  34 is a vertical sectional view taken along the line XXXIV-XXXIV in FIG. 35 showing the installation state when the acoustic shoe has a flat plate shape, and FIG. 35 is a plan sectional view. When the acoustic shoe 101b has a flat plate shape (disk shape), the outer shape is maintained even when the acoustic shoe 101 rotates around the Φ axis, and the stability of sensitivity is maintained.

  36 is a sectional view taken along the line XXXVI-XXXVI in FIG. 37 showing an installation state when the acoustic shoe has a tapered shape, and FIG. 37 is a plan sectional view. When the acoustic shoe 101c is tapered, the strength of the obtained shock wave can be improved by directing the lower end surface toward the processing point side.

  38 is a sectional view taken along the line XXXVIII-XXXVIII in FIG. 39 showing the installation state when the acoustic shoe has a cone shape, and FIG. 39 is a plan sectional view. When the acoustic shoe 101d has a cone shape, both the effect of the planar shape and the effect of the tapered shape can be obtained.

  40 is a cross-sectional view taken along the line XL-XL in FIG. 41 showing the installation state when the acoustic shoe is in a rotating semi-ellipsoidal shape, and FIG. 41 is a plan cross-sectional view. When the acoustic shoe 101e has a rotating semi-ellipsoidal shape, the same effect as in the cone shape can be expected.

  42 is a cross-sectional view taken along the line XLII-XLII in FIG. 43 showing the installation state when the acoustic sensor 10 is tilted, and FIG. 43 is a plan cross-sectional view. Sensitivity improvement can be expected by tilting the acoustic sensor 10 in the acoustic shoe 101f. Further, this arrangement may be used in combination with each of the cases shown in FIGS.

[Eighth Embodiment]
FIG. 44 is a conceptual sectional elevation view showing the configuration of the laser processing apparatus according to the eighth embodiment. FIG. 45 is a conceptual vertical sectional view showing a configuration of a modified example of the laser processing apparatus according to the eighth embodiment.

  This embodiment and the modification are modifications of the first embodiment. In these embodiments, the water supply to the water flow transmission unit 5 is provided by the water flow in the pipes flowing in from one or more directions. For example, if it is the structure which merges from two directions, it will become a modification shown in FIG. Here, each pipe | tube has flexibility and is the hose 124, for example. As a result, the condensing unit 12 and the water flow transmission unit 5 displayed in FIGS. 44 and 45 can move together.

  Inside the water flow transmission unit 5, a cylindrical buffer layer 121 that receives a water flow and a cylindrical injection layer 122 having a smaller diameter than the buffer layer 121 are continuously connected via a taper portion 123. A laser is transmitted.

  When water is supplied from two or more directions, in the buffer layer 121, the water flow in the hose 124 flowing in from the respective directions joins at the hose junction portion 124a. For example, as shown in FIGS. 44 and 45, each hose 124 may be provided with a nozzle 5 c in the water flow transmission unit 5, connected to the nozzle 5 c, and tightened with a binding band (not shown). 44 and 45 show an example in which the attachment angle of the nozzle 5c is inclined by about 60 degrees with respect to the outflow direction from the injection layer 122, but a smaller angle, that is, the outflow direction from the injection layer 122. Further, the direction in which the inflow direction of the nozzle 5c is closer may be used. Alternatively, it may be larger, for example, 90 degrees.

  As described above, the number of water supply routes, that is, the number of hoses 124 need not be limited to one, and may be two or more. Further, the diameter of the water supply route, that is, the hose 124, and the flow rate inside the hose 124 may or may not be aligned with each other.

  If air is taken into the flow of water flowing out from the tip of the injection layer 122 toward the workpiece 1 and the diameter of the water flow (diameter R of the water column) is widened, there is a risk of affecting the laser beam permeability in the water flow. is there. For this reason, it becomes possible to make the distance from the front-end | tip of the injection layer 122 to the to-be-processed member 1 large by making the water flow which flows out from the injection layer 122 not spread. In this way, a commutator 126 may be provided in the buffer layer 121 in order to suppress the spread of the diameter of the water flow flowing out from the tip of the injection layer 122 (water column diameter R).

  The commutator 126 rectifies the turbulent water flow in the hose junction 124a. The commutator 126 can also exert an effect of suppressing violent scattering after water hits the workpiece 1. The configuration of the commutator 126 will be described with reference to FIG.

  A disc-shaped air / water separation window 125 that transmits laser light is provided at the upstream end of the cylindrical buffer layer 121 of the water flow transmission unit 5. Part of the boundary. The condensing part 12 is provided outside the air / water separation window 125, that is, on the outside air side, and the laser light passes through the air / water separation window 125 after passing through the light condensing part 12 and further passes through the commutator 126 to be processed. It is transmitted to point 2.

  An O-ring 125b is provided on the inner side of the steam-water separation window 125, that is, on the water side, and a pressing plate 125a having an opening formed in the central portion is provided on the outer side of the steam-water separation window 125, that is, on the outside air side By compressing the O-ring 125b with the holding plate 125a, the water-tightness of the air / water separation window 125 is secured.

  As shown in FIGS. 44 and 45, the acoustic sensor 10 is installed outside the water flow transmission unit 5.

  FIG. 46 is a conceptual perspective view showing the configuration of the commutator of the laser processing apparatus. The commutator 126 includes a cylindrical rectifying cylinder 126a and four plate-shaped rectifying plates 126b. One side of the rectifying plate 126b is attached to the outer surface of the rectifying cylinder 126a, extends outward in the radial direction of the rectifying cylinder 126a, and extends in the axial direction. The rectifying plate 126b projects upstream from the rectifying cylinder 126a. The inner diameter of the rectifying cylinder 126b is set to be larger than the outer diameter of the laser beam so that the laser beam passes.

  Two circles 121a and 121b indicated by two-dot chain lines in FIG. 46 are part of the outer edge of the buffer layer 121, and the circle 121a corresponds to the upstream side of the circle 121b. The cylindrical curved surface including the circle 121a and the circle 121b, the rectifying cylinder 126a and the four rectifying plates 126b, the buffer layer 121 is divided by the rectifying plate 126b at the flow path in the rectifying cylinder 126a and the annular portion outside thereof. It is divided into four flow paths. The number of rectifying plates 126b is not limited to four, and may be three or five or more.

  Thus, by forming the flow path divided along the axial direction of the water flow transmission unit 5, the flow path can be adjusted, for example, by suppressing swirl flow.

  The rectifying plate 126b has been described as an example in which the rectifying plate 126a extends outward in the radial direction of the rectifying cylinder 126a and extends in the axial direction. Alternatively, they may be attached at an angle with respect to the axial direction, or both of them may be used. Alternatively, rectifying blades may be provided along the inner surface of the water flow transmission unit 5.

  As described above, the condensing unit 12 and the water flow transmission unit 5 can move together, and a rectified water flow can be supplied to the processing point 2.

  FIG. 47 is a conceptual vertical sectional view showing the configuration of another modification of the laser processing apparatus according to the eighth embodiment. As shown in FIG. 47, the acoustic sensor 10 may be installed inside the water flow transmission unit 5. As described above, when the acoustic sensor 10 is installed inside the water flow transmission unit 5, it may be installed upstream of the commutator 126 as shown in FIG. 47, or in order to avoid the influence of turbulent flow, the buffer layer 121. It may be better to install it downstream.

[Other Embodiments]
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention.

  Moreover, you may combine the characteristic of each embodiment. Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Work piece, 2 ... Processing point, 4 ... Plasma, 5 ... Water flow transmission part, 5a ... Water flow, 5b ... Water, 5c ... Nozzle, 6 ... Liquid, 8a ... Housing, 8b ... Front plate, 8c ... Electrode , 8d ... piezoelectric vibrator, 8f ... electrode, 10 ... acoustic sensor, 10a, 10b, 10c, 10d, 10e, 10f, 10g ... acoustic sensing unit, 11 ... laser light source, 11a ... laser light, 12 ... condensing unit, DESCRIPTION OF SYMBOLS 13 ... Light detection part, 15a, 15b ... Acoustic sensor, 21 ... Water flow source, 26 ... Acoustic signal transfer part, 30 ... Calculation part, 31 ... Time width acquisition part, 32 ... Distance calculation part, 40 ... Control part, 50 ... Condensing distance adjusting unit 60 ... Splashing adhesion preventing unit 61 ... Protective cover 62 ... Air blower 70 ... Water impact mitigating unit 80 ... External environmental effect mitigating unit 80a ... Mechanical vibration suppressing unit 80b ... Acoustic Noise reduction part, 80c ... Electrical noise reduction part DESCRIPTION OF SYMBOLS 90 ... Movement drive part, 91 ... Restraint part, 92 ... Arm, 93 ... Joint, 95 ... Power part, 100 ... Laser processing apparatus (laser beam irradiation apparatus), 101a, 101b, 101c, 101d, 101e, 101f ... Acoustic shoe 121 ... buffer layer, 122 ... injection layer, 123 ... taper, 124 ... hose, 124a ... hose junction, 125 ... gas-water separation window, 125a ... pressing plate, 125b ... O-ring, 126 ... commutator, 126a ... Rectifying cylinder, 126b ... Rectifying plate

Claims (9)

A laser light source that emits laser light;
A condensing unit that condenses the laser beam on a workpiece to be surface-cured,
A water flow transmission unit for supplying a water flow to the processing surface of the workpiece;
An acoustic sensor that is provided at a predetermined relative position with respect to at least one of the water flow transmission unit and the light collecting unit, and that receives sound from the processing surface;
A time width acquisition unit that acquires a measurement time width from a reference timing until the acoustic sensor receives sound; and
Based on the measurement time width, a distance calculation unit that calculates a distance from at least one of the water flow transmission unit and the light collecting unit to the processing surface;
A laser processing apparatus comprising: A light detection unit for detecting the laser beam;
The laser processing apparatus according to claim 1, wherein the time width acquisition unit uses a signal from the light detection unit to acquire the measurement time width.   The distance calculation unit is configured so that the acoustic sensor generates sound from the measurement time width acquired by the time acquisition unit and the reference timing when the distance between the light collecting unit and the processing surface is a predetermined reference distance. The laser processing apparatus according to claim 1, wherein a distance from the light collecting unit to the processing surface is calculated based on a difference from a reference measurement time width until reception timing.   The said acoustic sensor is provided with the acoustic sensing part, The said acoustic sensing part is orient | assigned to the said water flow which flows through the inside of the said water flow transmission part, The Claim 1 thru | or 3 characterized by the above-mentioned. Laser processing equipment.   5. The laser processing apparatus according to claim 1, wherein the water flow transmission unit is formed so as to be capable of receiving a water flow from a plurality of pipes. 6.   The laser processing apparatus according to claim 1, wherein the water flow transmission unit includes a commutator that rectifies the water flow. A reference measurement step for obtaining a reference measurement time width from when laser light irradiation is performed by a laser light irradiation device to a known reference distance until reception of sound generated by the laser light irradiation;
The laser light irradiation is performed by the laser light irradiation device by setting any one of a plurality of construction target positions of the construction target as an irradiation target position, and the laser light irradiation generates the laser light from the laser light irradiation. An irradiation step for obtaining a measurement time width until receiving sound; and
A distance calculating step of calculating a distance between the laser light irradiation apparatus and the irradiation target location based on the difference between the reference distance and the measurement time width acquired in the irradiation step and the reference measurement time width;
A laser processing method comprising: A distance determination step of determining whether or not the distance calculated in the distance calculation step is appropriate;
If it is not determined to be appropriate in the distance determination step, a distance correction step for correcting the distance and returning to the irradiation step;
When it is determined that the distance correction step is appropriate, it is determined that the construction target location corresponding to the irradiation target location that has been irradiated with the laser light in the irradiation step has been completed, and all locations of the construction target location A construction judgment step for judging whether or not construction has been completed;
If the construction determination step does not determine that all of the locations have been installed, one of the locations that are not determined to be installed is set as the irradiation target location, and the process returns to the irradiation step. Steps,
The laser processing method according to claim 7, further comprising: A reference measurement step in which the time width acquisition unit acquires a reference measurement time width for a known reference distance; and
Irradiation step in which the laser beam irradiation device performs laser beam irradiation and the time width acquisition unit acquires the measurement time width;
A distance calculating step of calculating a distance between the laser light irradiation device and the irradiation point of the laser light irradiation based on the difference between the reference distance and the measurement time width acquired in the irradiation step and the reference measurement time width;
A distance measuring method characterized by comprising:

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