JP5375476B2 - Method for estimating compressive stress value, compressive stress value estimating apparatus, and laser processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an estimation method of a compression stress value, a compression stress value estimator, and a laser processing apparatus for correctly estimating the magnitude of compression stress applied to a member to be processed having an opening such as a common rail. <P>SOLUTION: This method estimates the compression stress applied to the member to be processed in laser peening processing for irradiating the member to be processed having an opening a pulse laser beams, and applying the compression stress to the member to be processed, and includes: a step of obtaining a measurement result of an emission quantity of light generated by irradiating a peripheral portion of the opening in the member to be processed with a plurality of the pulse laser beams; a step of calculating the emission intensity of light generated in the vicinity of both ends of a diameter of the opening based on the measurement result of the emission quantity; and a step of referring to a database preset so as to indicate a correlation between the emission intensity and the compression stress, and estimating the magnitude of the applied compression stress based on the calculated emission intensity. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a compressive stress value estimation method, a compressive stress value estimation apparatus, and a laser processing apparatus when performing a laser peening process, and is particularly a technique suitable for a laser peening process for a member having a structure such as a common rail.

  The common rail is a pipe-like component that is positioned between a pump that pumps light oil of fuel and an injector in a pressure accumulation fuel injection system of a diesel engine, and that accumulates light oil. A pipe-shaped portion of the common rail (hereinafter referred to as a rail hole) has a role of accumulating light oil, and passes through an opening (hereinafter referred to as a branch hole) provided in the pipe-shaped portion. The light oil stored in the pipe is pumped to each injector. Here, with the operation of the engine, the light oil is periodically pumped, and the pressure of the light oil in the common rail fluctuates periodically. In this case, the circumferential tensile stress varies periodically in the rail hole and the branch hole of the common rail. Here, in the vicinity of the opening of the branch hole, particularly in the vicinity of both ends of the diameter parallel to the longitudinal direction of the rail hole of the branch hole, the tensile stress of the pipe-like part and the opening is combined, There is a problem that a tensile stress larger than that of the portion is generated and fatigue fracture is easily caused by fluctuations in internal pressure. If the fatigue strength against internal pressure fluctuation (internal pressure fatigue strength) is improved, high-pressure injection of fuel becomes possible, leading to cleaner exhaust gas and improved fuel consumption. Therefore, there is a demand for improved fatigue strength.

  Conventionally, as an approach for improving the fatigue strength, a method of increasing the fatigue strength of the common rail by using a high-strength steel material is generally employed. There are problems such as a decrease in workability and an increase in cost due to higher performance. Therefore, a method for improving the fatigue strength of the entire component by locally applying a compressive stress only to a portion where the fatigue strength is a problem has been studied. The laser peening process, which has been developed in recent years, irradiates the surface of a metal object with a pulsed laser beam having a high peak power density while placing a transparent medium such as a liquid on the surface of the metal object. This is a technique of applying residual compressive stress to the vicinity of the surface of a metal object by non-contact processing using force. For example, the method is disclosed in Patent Document 1 below. The laser beam can be transmitted to narrow portions such as the inner surface of the rail hole and the inner surface of the branch hole of the common rail, and laser peening is the only method for applying high compressive stress in the vicinity of the opening of the branch hole of the common rail. Therefore, as disclosed in Patent Document 2 below, when applying laser peening to a common rail, the circumferential compressive stress of the branch hole in the vicinity of both ends of the diameter parallel to the longitudinal direction of the rail hole is determined. A way to increase is being considered.

  In the laser peening process to the branch hole opening of the common rail described above, a prediction technique for determining whether or not the compressive stress is applied to a desired value is important. Therefore, there is a demand for a technique for estimating the compressive stress applied to the periphery of the opening of the branch hole on the inner surface of the rail hole in a nondestructive manner. For general mechanical parts, for example, the compressive stress in the processing area is directly measured using an X-ray residual stress measurement technique. However, in the common rail, it is necessary to measure the portion corresponding to the inner surface of the rail hole, and it is impossible to detect the diffracted X-ray at the same time as the X-ray is incident.

  On the other hand, for the estimation of the compressive stress value, there is an approach of estimating the compressive stress value by measuring some information during processing in real time. The following methods are known for real-time quality prediction in the laser peening process.

  For example, in Patent Document 3 below, in the laser peening process on the inner surface of the thin tube in the reactor pressure vessel, the inner surface of the thin tube is irradiated with an ultrasonic wave or laser light generated when an ultrahigh pressure is generated by irradiating the visible light laser. By detecting the infrared rays generated from the detected part, and comparing the detected ultrasonic waves and infrared rays with data representing the relationship between the ultrasonic waves and infrared rays measured in advance and the surface modification state, the surface by laser irradiation A method for monitoring the working conditions of reforming is disclosed.

  Also disclosed is a method for analyzing the intensity of spectral light from plasma generated from a portion irradiated with laser light. For example, in Patent Document 4 below, in a laser peening process for an object such as a moving blade of a gas turbine, the instantaneous spectral light intensity is measured and recorded in a short time over the duration of the plasma, and the time-lapse data of the recorded spectrum is used. A method for predicting quality from a correlation between a plasma temperature analyzed in advance and data obtained as data in advance and a fatigue test result is disclosed. Patent Document 5 below discloses a method for determining whether or not the laser peening process is operating properly based on the shape of a line spectrum that is a part of the spectrum light intensity. Furthermore, the following Patent Document 6 discloses a method for determining not only the quality defect but also its cause by measuring the intensity change of the line spectrum corresponding to the event causing the quality defect in the peening process. Is disclosed.

Japanese Patent No. 3373638 JP 2006-322446 A JP-A-11-285868 Japanese Patent Laid-Open No. 2001-124697 JP 2006-82222 A JP 2007-155743 A

  The following two points are characteristic in the laser peening process to the branch hole opening of the member to be processed having an opening such as a common rail.

  First is the shape. The part to be strengthened is in the vicinity of both ends of the diameter parallel to the longitudinal direction of the rail hole of the branch hole, and the laser processing region includes a region called a branch hole where material is missing from the rail hole. In addition, the periphery of the opening of the branch hole is subjected to electrolytic polishing in order to increase the fatigue strength of the common rail by reducing the stress concentration, and the laser processing area includes an inclined surface that falls into the branch hole. become. From the above, the laser processing area of the opening of the branch hole includes not only a continuously connected plane or curved surface but a notch called a branch hole and an inclined surface connected to the branch hole. Therefore, a quality prediction method based on the fact that the laser processing area is a special area including such a notch and an inclined surface is desired.

Second, the desirable compressive stress distribution is also characteristic.
The region to which the compressive stress is to be applied is a very limited region of about 1 mm ² located at both ends of the diameter. And compressive stress is a specific direction called the peripheral direction of a branch hole. Therefore, a quality prediction method based on such locality and directionality is desired.

  The quality prediction methods disclosed in Patent Documents 3 to 6 are all premised on laser peening processing on continuously connected surfaces without notches and the like. It could not be used to determine whether compressive stress was applied to the opening. For example, from the viewpoint of the above-mentioned shape, according to the determination rule based on the premise of processing on a normal continuous surface, for a pulse laser beam in which the irradiation spot of the laser beam overlaps the branch hole, Since the amount of light emission of plasma becomes insufficient, even if the process itself is normal, it is determined to be defective. Also, from the viewpoint of compressive stress distribution, the quality prediction methods disclosed in Patent Documents 3 to 6 are all based on the technical idea of determining the quality of processing quality for each one-shot irradiation of a pulse laser beam. In other words, it was insufficient to predict the compressive stress generated as a result of the superposition of irradiation with a large number of pulsed laser beams.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is given by a laser peening process to a member to be processed having a structure such as an opening such as a common rail. It is an object of the present invention to provide a compressive stress value estimation method, a compressive stress value estimation device, and a laser processing device capable of more accurately estimating the magnitude of the compressive stress.

In order to solve the above problems, according to an aspect of the present invention, in a laser peening process in which a processing member having an opening is irradiated with a pulsed laser beam and compressive stress is applied to the processing member. A method for estimating a compressive stress applied to a member to be processed, which is a light emission amount that is time waveform data of light generated by irradiating a plurality of pulse laser beams to the periphery of the opening of the member to be processed calculating on the basis of acquiring the measurement results, the emission intensity is the peak value or the time integral value of the emission amount of the light generated near the ends of the diameter of the opening, the light emission amount of the measurement results And estimating a magnitude of the applied compressive stress based on the calculated light emission intensity with reference to a preset database indicating the correlation between the light emission intensity and the compressive stress , Only contains, in the step of calculating the emission intensity from among the light emission amount of the measurement results to identify the amount of light emission of emission at around the end of the diameter of the opening area, the area A method for estimating the compressive stress value for calculating the sum of the emission intensities is provided.

  In the step of calculating the light emission intensity, the light emission amount of light emission in an elliptical region centering on an end of the diameter of the opening is specified from the measurement result of the light emission amount, and light emission is performed in the region. It is preferable to calculate the sum of the intensities.

  A plurality of the openings are provided along the longitudinal direction of the member to be processed, and the major axis direction of the elliptical region is preferably a direction orthogonal to the longitudinal direction of the member to be processed. .

  In the step of calculating the light emission intensity, a weighting coefficient corresponding to a distance from an end of the diameter of the opening is added to each of the light emission intensities included in the region to calculate a total light emission intensity. May be.

  The weighting coefficient may be a value obtained from a Gaussian distribution having a distance from an end of the diameter of the opening as a variable.

  Between the step of calculating the light emission intensity and the step of estimating the magnitude of the compressive stress, the center position of the opening is specified based on the distribution of the light emission intensity, and the center position is determined based on the determination result of the center position. The method may further include a step of correcting information indicating a position irradiated with the pulse laser beam.

  In the step of correcting the information indicating the position irradiated with the pulse laser beam, the position giving the minimum value of the emission intensity in the emission intensity distribution may be specified as the center position of the opening.

In order to solve the above problems, according to another aspect of the present invention, a laser that irradiates a member to be processed having an opening with a pulsed laser beam and applies compressive stress to the member to be processed. In a peening process, a compressive stress value estimation device for estimating a compressive stress applied to a member to be processed, the light generated by irradiating a plurality of pulsed laser beams around the opening of the member to be processed A measurement data acquisition unit that acquires measurement data related to the light emission amount that is time waveform data, and an intensity that calculates a light emission intensity that is a peak value or a time integral value of the light emission amount based on the measurement data related to the light emission amount A calculation unit, and a total calculation unit for calculating a sum of light emission intensities of light generated near both ends of the diameter of the opening based on the light emission intensity calculated by the intensity calculation unit; A stress value estimation unit that estimates a magnitude of the applied compressive stress based on a total sum of the emission intensities calculated by the total calculation unit with reference to a preset database showing a correlation between the emission intensity and the compression stress; A coordinate data acquisition unit that acquires coordinate data that is data representing the irradiation position of the pulse laser beam, and the sum total calculation unit is generated near both ends of the diameter of the opening based on the coordinate data There is provided a compressive stress value estimation device for calculating the sum of the emission intensity of the emitted light .

  The total calculation unit may calculate a total sum of light emission intensities in a region centered on an end of the diameter of the opening.

  It is preferable that the sum total calculation unit calculates a sum of light emission intensities in an elliptical region centered on an end of the diameter of the opening.

  A plurality of the openings are provided along the longitudinal direction of the member to be processed, and the sum total calculation unit orthogonally intersects the longitudinal direction of the elliptical region with the longitudinal direction of the member to be processed. The direction is preferred.

  The sum total calculation unit may calculate a sum of the light emission intensities by adding a weighting coefficient corresponding to a distance from an end of the diameter of the opening to each of the light emission intensities included in the region. .

  The sum total calculation unit may use a value obtained from a Gaussian distribution with a distance from an end of the diameter of the opening as a variable as the weighting coefficient.

  The compressive stress value estimation device identifies the center position of the opening based on the emission intensity distribution calculated by the intensity calculation unit, and the pulse laser beam is irradiated based on the identification result of the center position. You may further provide the position correction | amendment part which correct | amends the coordinate data showing a position.

  The position correction unit may specify a position that gives a minimum value of emission intensity in the emission intensity distribution as a center position of the opening.

  In order to solve the above-described problem, according to still another aspect of the present invention, a member to be processed having an opening is irradiated with a pulse laser beam to apply a compressive stress to the member to be processed. A laser processing apparatus capable of performing a laser peening process, wherein a laser beam oscillator that irradiates the target member with a pulse laser beam having a predetermined wavelength, and a plurality of pulse laser beams around an opening of the target member A laser irradiation apparatus comprising: an irradiation head that irradiates and collects light generated by irradiation of the pulse laser beam; and a detection element that detects light generated by irradiation of the pulse laser beam; and the compression stress described above A laser processing apparatus comprising a value estimation device is provided.

  As described above, according to the present invention, a member to be processed having a complicated structure such as an opening such as a common rail can be calculated more accurately by calculating the emission intensity of light emitted by irradiation with a number of pulsed laser beams. It is possible to accurately estimate the magnitude of the compressive stress applied to. Thereby, the quality determination of the laser peening process can be performed more accurately, and the reliability of the laser peening process can be improved.

It is explanatory drawing for demonstrating a common rail. It is explanatory drawing for demonstrating a common rail. It is explanatory drawing for demonstrating a common rail. It is explanatory drawing for demonstrating the laser processing apparatus which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating an irradiation head. It is explanatory drawing for demonstrating an irradiation head. It is explanatory drawing for demonstrating the irradiation method of a laser. It is a block diagram for demonstrating the structure of the irradiation position control apparatus which concerns on the same embodiment. It is a block diagram for demonstrating the structure of the compressive-stress value estimation apparatus which concerns on the same embodiment. It is explanatory drawing for demonstrating the data which the compressive-stress value estimation apparatus which concerns on the same embodiment acquires. It is explanatory drawing for demonstrating the light emission resulting from a plasma. It is explanatory drawing for demonstrating the range used for calculation of the sum total of emitted light intensity. It is explanatory drawing for demonstrating the range used for calculation of the sum total of emitted light intensity. It is a graph for demonstrating the anisotropy of a stress value. It is a flowchart for demonstrating the estimation method of the compressive stress value which concerns on the same embodiment. It is a block diagram for demonstrating the structure of the compressive-stress value estimation apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart for demonstrating the estimation method of the compressive stress value which concerns on the same embodiment. It is a block diagram for demonstrating the hardware constitutions of the compressive-stress value estimation apparatus which concerns on embodiment of this invention. FIG. 3 is a graph showing the relationship between the total light emission intensity and the circumferential stress in Example 1. FIG. 6 is a graph showing the relationship between the total light emission intensity and the circumferential stress in Example 2. FIG. 6 is a graph showing the relationship between the total emission intensity and the circumferential stress in Example 3.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  Hereinafter, a common rail will be described in detail as an example of a member to be processed having an opening.

(About common rail)
First, prior to describing a compressive stress value estimation apparatus and a compressive stress value estimation method according to an embodiment of the present invention, a common rail that is a member to be processed will be briefly described with reference to FIGS. 1-3 is explanatory drawing for demonstrating a common rail.

  For example, as shown in FIGS. 1 (a) and 1 (b), the common rail 1 includes a pipe-shaped cylindrical wall portion 2 and a plurality of branch pipes 3 provided along the longitudinal direction of the cylindrical wall portion 2. Is provided. FIG.1 (c) is sectional drawing which cut | disconnected the common rail 1 shown to Fig.1 (a) along the AA cut line. As shown in FIG. 1C, a rail hole 4 is formed inside the cylindrical wall portion 2 along the longitudinal direction of the cylindrical wall portion 2. This rail hole 4 is a main pipe of the common rail 1 and has a role of accumulating light oil.

Further, as shown in FIG. 1C, the rail hole 4 is provided with a plurality of branch holes 5 that open vertically. The light oil stored in the rail hole 4 is pumped to the branch pipe 3 through the branch hole 5. Inside diameter _{d 1} of the rail hole 4 is about 10 mm, an inner diameter _{d 2} of the branch hole 5 is about 1 mm. Since light oil is periodically pumped with the operation of the engine and the pressure of the light oil in the common rail 1 varies periodically, it is preferable to use a steel material having a tensile strength of about 600 MPa or more as the material of the common rail 1.

  As described above, the rail hole 4 and the branch hole 5 periodically vary in the tensile stress in the circumferential direction. FIG. 2 shows an enlarged peripheral portion of the boundary between the branch hole 5 and the inner surface of the rail hole 4, which is an opening peripheral portion of the branch hole 5. Among the peripheral portions of the opening of the branch hole 5, the tensile stress of the rail hole 4 and the branch hole 5 is synthesized especially in the vicinity 6 at both ends of the diameter parallel to the longitudinal direction of the rail hole 4 of the branch hole 5. A tensile stress larger than that of the portion is generated. As a result, in the vicinity 6 at both ends of the diameter, the fluctuation of the internal pressure becomes large and fatigue failure is likely to occur. Therefore, in order to improve the fatigue strength of such a portion, for example, as shown in FIG. 3, which is a cross-sectional view with a plane including the axial direction of the rail hole 4 and the axial direction of the branch hole 5 as a cut surface. Conventionally, electrolytic polishing is performed on the connecting portion between the inner wall 7 of the rail hole 4 and the inner wall 8 of the branch hole 5 to form an inclined surface, thereby reducing the stress concentration around the opening.

  When compressive stress is applied in the circumferential direction of the branch hole 5 using the laser peening process, an area where the laser process is performed (hereinafter referred to as a laser process area) is inclined as shown in the area 9 of FIG. It is an area including a surface. In this region, an inclined surface is formed by electropolishing, so the influence of the irradiated laser changes according to the inclined surface, and the laser peening process is performed compared to the case where the laser peening process is performed on a flat surface. It becomes difficult to determine the quality of the peening process.

  Therefore, in the embodiment of the present invention, a laser peening process is performed on a member having a complicated shape having an opening such as a common rail by using a compressive stress value estimation method as described below. Even if it exists, it becomes possible to perform the quality determination of a laser peening process correctly.

(First embodiment)
<About laser processing equipment>
Subsequently, an example of a laser processing apparatus that includes the compressive stress value estimation apparatus according to the first embodiment of the present invention and can perform laser peening processing on the common rail 1 will be described with reference to FIG. To do. FIG. 4 is an explanatory diagram for explaining the configuration of the laser processing apparatus 10 according to the present embodiment.

  The laser processing apparatus 10 according to the present embodiment mainly includes a laser irradiation apparatus 100, a compression stress value estimation apparatus 200, an irradiation position control apparatus 300, and a water supply pump 400, for example, as shown in FIG. .

[About laser irradiation equipment]
The laser irradiation apparatus 100 is an apparatus that transmits a pulsed laser beam L to a common rail 1 that is an object to be processed, and irradiates a desired portion of the common rail 1 to be processed with the pulsed laser beam L. The laser irradiation apparatus 100 includes a laser beam oscillator 101, an optical system that transmits a pulse laser beam L, an irradiation head 111 that irradiates the pulse laser beam L, a rotation driving device 113 that controls the position of the irradiation head, and parallel driving. The apparatus 115 is mainly provided.

The laser beam oscillator 101 is a device that oscillates a pulsed laser beam L having a predetermined wavelength used for laser peening processing. Since the laser peening process is performed in the presence of water as will be described later, it is preferable that the predetermined wavelength of the laser beam has good underwater permeability. As such a laser beam, for example, the second harmonic (wavelength 532 nm) of an Nd: YAG laser or the second harmonic (wavelength 532 nm) of an Nd: YVO ₄ laser can be cited. The peak power density of the pulsed laser beam is an important parameter that determines the pressure of plasma during processing, and hence the level of compressive stress after processing, and a suitable range is about 10 to 1000 TW / m ² . As a typical range of other parameters, the pulse energy is about 1 mJ to 10 J, and the pulse time width is about 100 ps to 100 ns.

  The pulsed laser beam L oscillated from the laser beam oscillator 101 is collected by the condenser lens 103 and transmitted to the optical fiber 107 through the coupling port 105. The optical fiber 107 passes through the inside of the support rod 109 and is connected to an irradiation head 111 described later. The pulse laser beam L travels through the optical fiber 109 and is transmitted to the irradiation head 111.

  As shown in FIG. 4, the irradiation head 111 is inserted into the rail hole 4 of the common rail 1, and the pulse laser beam L emitted from the irradiation head 111 irradiates the periphery of the branch hole opening that is a part of the rail hole 4. Is done.

  Here, the support rod 109, to which the irradiation head 111 is connected at one end, is connected to a rotation driving device 113, and the rotation driving device 113 is a parallel driving device 115 placed on an optical test bench or a production line. It is placed on top. The position of the support rod 109 (and thus the irradiation head 111) can be controlled by these driving devices. The irradiation head 111 translates in the longitudinal direction of the rail hole inside the rail hole 4 and supports the support rod. Rotational motion with 109 as the rotation axis is possible. There are a plurality of branch holes 5 to be subjected to the laser peening process, and the irradiation head 111 is moved to a position where the plurality of branch holes 5 are present by the parallel drive device 115.

  5A and 5B are explanatory views for explaining the configuration of the irradiation head 111. FIG. The irradiation head 111 has a case made of a hollow member, in which a fiber end 131 from which the pulse laser beam L transmitted through the optical fiber 107 is emitted, a condensing lens 133, and a mirror 135 are provided. And are attached. The mirror 135 has a shape obtained by obliquely cutting a cylinder, and is a so-called rod-type mirror. The mirror 135 is bonded to the mirror base 137. The pulse laser beam L emitted from the fiber end 131 is bent by the condenser lens 133, then reflected by the mirror 135, and reaches the condensing point F. Here, the shape of the laser spot at the condensing point F may be any shape, but since the shape of the end of the optical fiber 107 is projected, it is often substantially circular.

  In the vicinity of the condensing point F, a water flow is generated by the water supplied by the water supply pump 400 through the water supply pipe 401, and water exists on the mirror 135 side of the condensing lens 133. . Therefore, the condenser lens 133 is preferably formed using a material having a higher refractive index than water in order to obtain sufficient bending. At the same time, the condensing lens 133 is preferably made of a material having durability against the pulsed laser beam L having a high peak power density. An example of a lens material having such characteristics is sapphire.

  Further, at the condensing point F, metal particles are generated from the common rail 1 by being irradiated with the pulse laser beam L. However, as described above, a water flow is generated in the vicinity of the condensing point F. It is possible to prevent the mirror 135 from being contaminated by the generated metal fine particles.

  The irradiation head 111 is not limited to the combination of the condenser lens 133 and the mirror 135 as shown in FIG. 5A, but as shown in FIG. 5B, the collimator lens 139 and the parabolic mirror. 141 may be combined.

  The laser peening process is performed by scanning the laser beam irradiation spot of the pulsed laser beam L on the periphery of the opening provided with the branch hole 5 while superimposing the spot. In the laser peening process, residual compressive stress can be applied to the vicinity of the laser irradiation surface by the following mechanism. First, plasma is generated by irradiation with a pulsed laser beam having a high peak power density. Here, since a transparent medium such as water exists in the vicinity of the irradiated surface, the expansion of the plasma is suppressed and the pressure of the plasma is increased. Due to the reaction force of the high-pressure plasma, plastic deformation can be applied in the vicinity of the surface of the laser irradiation spot, and residual compressive stress can be applied in the vicinity of this surface.

  The movement of the position of the laser beam irradiation spot is realized by moving the entire irradiation head 111 inside the rail hole 4 by a parallel driving device 115 and a rotation driving device 113 controlled by an irradiation position control device 300 described later. .

  In order to increase the compressive stress in the circumferential direction of the rail hole in the vicinity 6 at both ends of the diameter parallel to the longitudinal direction of the rail hole 4 around the opening (that is, the axial direction of the rail hole 4), for example, as shown in FIG. The laser beam irradiated portion (hereinafter also referred to as a beam spot) is scanned in a direction parallel to the axial direction of the rail hole 4, and this beam spot is scanned a plurality of times while shifting the position in the circumferential direction of the rail hole 4. The method is preferably used. At this time, the average value of the number of times of irradiation with the pulse laser beam with respect to the same point (hereinafter referred to as the average number of times of superimposition) is preferably set to 2 times or more (see, for example, Patent Document 2).

Here, the average number of times of superposition of the pulse laser beam means that the area of the beam spot is S ₀ , and the pulse laser beam with respect to the same point when the region of the area S ₁ is superimposed and irradiated by N times of irradiation with the pulse laser beam. Is the average value of the number of irradiations, and is defined by (S ₀ × N) / S ₁ . By setting the average number of superposition times to 2 or more, anisotropy can be generated in the residual compressive stress on the surface, and the compressive stress in the circumferential direction of the branch hole 5 can be selectively strengthened.

  Light is generated in the vicinity of the condensing point by the plasma generated in the vicinity of the condensing point F of the pulse laser beam (that is, the processing point of the laser peening process). The generated light also includes light having a wavelength different from that of the laser beam for laser peening processing, follows a path in the opposite direction to the laser beam, and passes through the optical fiber 107 incident from the end portion 131 of the optical fiber. The connection port 105 is returned to. The light emitted from the coupling port 105 passes through the lens 103 and is reflected by the mirror 117 that transmits only the wavelength of the laser beam. The mirror 117 may be an interference mirror. The reflected light (hereinafter also referred to as return light) is transmitted to the light emission detecting element 119 provided on the optical path. As a result, the light emission detection element 119 detects the light emission amount of the return light, which is a fixed portion of the light generated in the vicinity of the condensing point.

  The compressive stress value estimation apparatus 200 described later uses the light emission amount detected by the light emission detection element 119 to estimate the compressive stress value applied to the member to be processed by a method described later.

  Since the temperature of the plasma reaches several thousand K although it is instantaneous, the main spectrum of light emission from the plasma belongs to the visible light band to the near infrared wavelength region, and an optical fiber for a normal visible light band. 107 can be easily passed. For example, a photodiode can be used as the light emission detection element 119. Moreover, the optical filter 121 can be installed in front of the light emission detection element 119 as needed. As the optical filter 119, for example, a laser light cut filter for blocking reflected light or stray light from a condensing point of a laser beam for laser peening processing, an attenuation filter for adjusting the amount of light in the entire visible light band, or the like. It is possible to install. Further, for example, by using a bandpass filter centered at 440 nm, which is one of the emission spectra of iron ions, it is also possible to extract the emission of iron ions that are the main component of the steel material. Furthermore, the above filters can be used in appropriate combination.

[Compression stress estimation device]
Subsequently, the compressive stress value estimation apparatus 200 according to the present embodiment will be described.
The compressive stress value estimation apparatus 200 according to the present embodiment acquires measurement data related to the light emission amount acquired from the light emission detection element 119 of the laser irradiation apparatus 100, and compresses applied to a common rail that is a member to be processed for laser peening processing. It is an apparatus for estimating the magnitude of the stress value.

  In addition, the compressive stress value estimation apparatus 200 according to the present embodiment, when estimating the compressive stress value, is a coordinate that represents a position (laser irradiation position) obtained by laser irradiation acquired from an irradiation position control apparatus 300 described later. Data is acquired and used for the estimation process of the compressive stress value.

  The compressive stress value estimation apparatus 200 will be described in detail later again.

[Irradiation position control device]
Then, the irradiation position control apparatus 300 which concerns on this embodiment is demonstrated.
The irradiation position control device 300 according to this embodiment includes a rotation driving device 113 that rotates a support rod 109 to which the irradiation head 111 is connected as a rotation axis, and a support rod 109 in the axial direction, that is, a rail. This is a device for controlling the irradiation position of a pulsed laser beam used for laser peening by performing drive control of a parallel drive device 115 that translates in the depth direction of the hole 4. Below, this irradiation position control apparatus 300 is demonstrated, referring FIG. FIG. 7 is a block diagram for explaining the configuration of the irradiation position control apparatus 300 according to the present embodiment.

  The irradiation position control apparatus 300 according to the present embodiment includes, as shown in FIG. 7, for example, a drive control unit 301, a coordinate data acquisition unit 303, a coordinate data transmission unit 305, and a storage unit 307. Prepare for.

  The drive control unit 301 is realized by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication device, and the like. The drive control unit 301 is based on a drive control pattern designated by the user of the laser processing apparatus 10, a drive control pattern registered in advance in the storage unit 307 or the like, which will be described later, and the like. The drive control is performed. Thereby, in the laser processing apparatus 10 which concerns on this embodiment, the irradiation position to the to-be-processed member of the pulsed laser beam L inject | emitted from the laser beam oscillator 101 can be controlled.

  The coordinate data acquisition unit 303 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The coordinate data acquisition unit 303 acquires coordinate data representing the rotation amount of the support rod 109 (and thus the irradiation head 111) from the rotation driving device 113. In addition, the coordinate data acquisition unit 303 acquires coordinate data representing the amount of parallel movement of the support rod 109 (and thus the irradiation head 111) from the parallel drive device 115. In acquiring these coordinate data, the coordinate data acquisition unit 303 acquires a control signal related to the irradiation timing of the laser beam from the laser beam oscillator 101, the timing at which the pulse laser beam is irradiated, and the timing at which these coordinate data are acquired. It is preferable to synchronize with. By synchronizing with the irradiation timing of the pulse laser beam, the coordinate data acquisition unit 303 can clarify the irradiation position of all the irradiated pulse laser beams. In addition to the above configuration, coordinate data representing the rotation amount and coordinate data representing the amount of parallel movement are separately provided with a position sensor such as a rotary encoder or a laser distance meter, and the position of the irradiation head 111 is measured. The coordinate data acquisition unit 303 may be input.

  The coordinate data acquisition unit 303 transmits the acquired two types of coordinate data to a coordinate data transmission unit 305 described later. In addition, the coordinate data acquisition unit 303 may store the acquired coordinate data in the storage unit 307 described later.

  The coordinate data transmission unit 305 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The coordinate data transmission unit 305 transmits the coordinate data representing the irradiation position of the pulse laser beam transmitted from the coordinate data acquisition unit 303 to the compression stress value estimation apparatus 200. It is preferable to transmit the coordinate data to the compressive stress value estimation apparatus 200 every time coordinate data is transmitted from the coordinate data acquisition unit 303. Thereby, the compressive stress value estimation apparatus 200 can easily grasp the correspondence relationship between the measurement data relating to the observed light emission amount and the pulse laser beam causing the light emission.

The storage unit 307 is an example of a storage device included in the irradiation position control device 300.
The storage unit 307 stores, for example, drive control patterns for the rotary drive device 113 and the parallel drive device 115. Further, in the storage unit 307, the irradiation position control device 300 according to the present embodiment stores various parameters, the progress of processing, or various databases that need to be stored when performing some processing, or various databases, Recorded as appropriate. The storage unit 307 can be freely read and written by the drive control unit 301, the coordinate data acquisition unit 303, the coordinate data transmission unit 305, and the like.

  Heretofore, an example of the function of the irradiation position control apparatus 300 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  In addition, each function of the irradiation position control apparatus according to the present embodiment as described above is produced by creating a computer program or the like to be realized and mounted on a personal computer, PLC (Programmable Logic Controller) or the like, or by a sequencer It is possible to realize. A computer-readable recording medium storing such a computer program or the like can also be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

<Configuration of compressive stress value estimation device>
Next, the configuration of the compressive stress value estimation apparatus according to the first embodiment of the present invention will be described in detail with reference to FIG. FIG. 8 is a block diagram for explaining the configuration of the compressive stress value estimation apparatus according to the present embodiment.

  The compressive stress value estimation apparatus 200 according to the present embodiment includes, for example, a measurement data acquisition unit 201, a coordinate data acquisition unit 203, an intensity calculation unit 205, a total calculation unit 207, a stress value, as illustrated in FIG. An estimation unit 209 and a storage unit 211 are mainly provided.

  The measurement data acquisition unit 201 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The measurement data acquisition unit 201 acquires measurement data regarding the light emission amount of light generated by irradiating a plurality of pulsed laser beams to the periphery of the common rail opening from the light emission detection element 119 of the laser irradiation apparatus 100. It is preferable that the measurement data acquisition unit 201 acquires measurement data regarding the light emission amount from the light emission detection element 119 in real time. The measurement data acquisition unit 201 outputs the acquired measurement data to the intensity calculation unit 205 described later. The measurement data acquisition unit 201 may temporarily record the acquired measurement data in the storage unit 211 described later.

  When the measurement data acquisition unit 201 temporarily records the measurement data in the storage unit 211, the correspondence relationship with the coordinate data representing the irradiation position recorded in the storage unit 211 by the coordinate data acquisition unit 203 described later is clear. It is preferable to record the measurement data so that

  The coordinate data acquisition unit 203 is realized by, for example, a CPU, a ROM, a RAM, a communication device, and the like. The coordinate data acquisition unit 203 acquires coordinate data representing the irradiation position of the pulse laser beam transmitted from the irradiation position control device 300. The coordinate data acquisition unit 203 records coordinate data representing the acquired irradiation position of the pulse laser beam in the storage unit 211 described later.

  The coordinate data input from the irradiation position control device 300 includes, for example, coordinate data r regarding the parallel movement amount of the irradiation head 111 and coordinate data θ regarding the rotation amount of the irradiation head 111, as shown in FIG. By using these two types of coordinate data, the position irradiated with the pulse laser beam can be expressed. For example, as shown in FIG. 9, the coordinate data r regarding the parallel movement amount is data expressed as a relative value with the end of the rail hole 4 as a reference (r = 0), and the coordinate data regarding the rotation amount. θ is data expressed as a relative value with the vertical direction as a reference (θ = 0). The coordinate data acquisition unit 203 may record these coordinate data in the storage unit 211 as values obtained. In addition, the coordinate data acquisition unit 203 converts the irradiation position represented by the two types of acquired data into a coordinate system used to indicate the shape of the common rail 1 that is a member to be processed, and then stores the storage unit. 211 may be recorded.

  The intensity calculation unit 205 is realized by, for example, a CPU, a ROM, a RAM, and the like. The intensity calculation unit 205 calculates the light emission intensity of the light generated by the laser peening process based on the measurement data related to the light emission amount transmitted from the measurement data acquisition unit 201.

  In the laser irradiation apparatus 100 according to the present embodiment, a pulse laser beam having a predetermined pulse width (for example, about 100 ps to 100 ns) is emitted at a predetermined pulse interval (for example, about 10 ms), and irradiated to the peripheral portion of the common rail opening. Is done. As a result, plasma is generated by the irradiated pulse laser beam in the periphery of the opening, and light belonging to the visible light band is generated by the plasma. Since the duration of the plasma is longer than the pulse width of the pulse laser beam, for example, about 1 μs, the measurement data relating to the light emission amount detected by the light emission detecting element 119 is, for example, data having a waveform as shown in FIG. It becomes.

The intensity calculation unit 205 may refer to the measurement data input from the measurement data acquisition unit 201 and use the peak value (I _max ) of the time waveform data as illustrated in FIG. 10 as the emission intensity of the corresponding light emission. . Further, the intensity calculation unit 205 may use the time integral of the time waveform data (the area of the hatched portion in FIG. 10) as the emission intensity of the corresponding light emission instead of the peak value of the time waveform data.

  When the calculation of the light emission intensity is completed, the intensity calculation unit 205 records the calculated light emission intensity in the storage unit 211. At this time, for example, as shown in FIG. 9, the intensity calculation unit 205 associates the coordinate data representing the irradiation position recorded in the storage unit 211 by the coordinate data acquisition unit 203 so as to clarify the correspondence, It is preferable to record data relating to the emission intensity.

  In this way, the storage unit 211 to be described later includes the irradiation positions of all the pulse laser beams irradiated in the processing to the peripheral portion of the opening of one branch hole 5 and the emission intensity values corresponding to the irradiation positions. Will be stored.

  The sum total calculation unit 207 is realized by, for example, a CPU, a ROM, a RAM, and the like. The sum total calculation unit 207 calculates the total sum of the light emission intensities generated near both ends of the diameter of the opening provided in the member to be processed based on the light emission intensity calculated by the intensity calculation unit 205. The calculation process of the total sum of the emission intensities is performed when the laser peening process to the opening peripheral part of a certain branch hole 5 is completed.

  In the laser peening process for the common rail 1, both ends of the diameter parallel to the axial direction of the rail hole around the opening of the branch hole are points to be strengthened. Hereinafter, both ends of the diameter orthogonal to the axial direction of the rail hole 4 of the branch hole 5 are referred to as point A and point B, respectively. The sum total calculation unit 207 calculates the total sum of the emission intensities I with respect to the pulse laser beam irradiated to a predetermined range in the vicinity of the points A and B, which are points to be strengthened, based on the following Equation 1.

・・・（式１）

... (Formula 1)

In the above formula 1, S _A is the sum of the emission intensity I in a predetermined range near the point A, and S _B is the sum of the emission intensity I in a predetermined range near the point B. R _A represents a region in the vicinity of the point A to be considered when calculating the sum of the emission intensity I, and R _B represents a region in the vicinity of the point B to be considered when calculating the sum of the emission intensity I. Represent.

Here will be described the range R _A and R _B considers the sum in the above equation 1.
In the laser peening process, a single pulsed laser beam affects not only the range of the irradiation spot of the pulsed laser beam but also the peripheral portion to apply compressive stress. The range affected by the application of compressive stress is substantially circular, and is a region within a predetermined radius from the center of the irradiation spot.

The compressive stress values at points A and B, which are points to be strengthened by compressive stress, are generated as a result of superimposing compressive stress applying effects by the individual pulse laser beams irradiated around the respective points. Therefore, in order to calculate the sums S _A and S _B correlated with the compressive stresses at the points _A and _B , the regions R _A and R _B to be considered are, for example, as shown in FIG. A range in which the compressive stress values at the points A and B are affected by the irradiation of the pulse laser beam, that is, a region within the radius U centering on the points A and B is preferable. The size of the radius U depends on the irradiation condition of the pulse laser beam and the like, but it is often sufficient that the radius U is about twice the diameter of the beam spot with the points A and B as the center.

  First, the sum total calculation unit 207 refers to a data set composed of irradiation positions and light emission intensities stored in the storage unit 211, and specifies irradiation positions included within the radius U from the target point to be strengthened. . Thereafter, the sum total calculation unit 207 obtains the magnitude of the emission intensity I corresponding to the irradiation position included within the radius U from the data set, and calculates the total sum of the emission intensity I based on the above formula 1.

In the example shown in FIG. 11, the area to be considered is a circular shape having a radius U, but the radius U is anisotropic as shown in FIG. The shape is more preferable. More specifically, for example, as illustrated in FIG. 12, the sum total calculation unit 207 includes a radius U _{Z in} a direction parallel to the axial direction of the rail hole 4 and a radius U _{R in} a direction parallel to the circumferential direction of the rail hole 4. It is more preferable to consider a region having a substantially elliptical shape. Hereinafter, the reason why it is more preferable to consider the elliptical region will be described.

  At points A and B, which are points to be strengthened, the direction in which the compressive stress is to be strengthened is the circumferential direction of the rail hole 4. On the other hand, the range in which the compressive stress is affected by each pulsed laser beam is not completely isotropic and has directionality. Below, the directionality of the range in which the influence of compressive stress reaches is demonstrated, showing an example.

FIG. 13 is a graph showing stress application characteristics when a flat plate is manufactured using a steel material used for manufacturing the common rail and only one pulse laser beam is irradiated to the flat plate. In this example, the laser beam is a double wave (wavelength 532 nm) of an Nd: YAG laser with high water permeability, the pulse energy is 100 mJ, the pulse time width is 10 ns, the laser beam spot diameter is 0.6 mm, The pulse repetition frequency was 100 Hz. The flat plate was irradiated with one pulse of such laser beam irradiation conditions, and the stress distribution generated around the irradiated region was measured using an X-ray residual stress measurement apparatus. In FIG. 13, the radial stress of the laser beam spot is represented by σ _r , and the circumferential stress of the laser beam spot is represented by σ _θ .

As is apparent from FIG. 13, it can be seen that compressive stress is applied to a region wider than the spot diameter of the laser beam of 0.6 mm. The influence of the compressive stress reaches about 1.5 mm in the radial direction σ _r , and reaches about 1.0 mm in the circumferential direction σ _θ .

As is clear from this result, the influence of the compressive stress extends farther in the radial direction than in the circumferential direction. Based on the above, in FIG. 12, in order to obtain a sum having a correlation with the compressive stress in the circumferential direction at the points A and B, the sum calculation unit 207 preferably _satisfies U _R > U _Z.

  Note that the above formula 1 calculates the sum by treating all irradiation positions included in the region to be considered when calculating the sum equivalently, but the sum calculation unit 207 should consider As for the irradiation positions included in the region, the sum may be calculated assuming that the irradiation position closer to the point to be enhanced gives a greater contribution. That is, instead of the above formula 1, the following formula 2 may be used to calculate the total light emission intensity while accumulating the weighting coefficients.

・・・（式２）

... (Formula 2)

In the above formula 2, _{w n} is a weighting factor. Any weighting factor can be used as long as it reflects the extent of the shape of the stress distribution as shown in FIG. 13, for example. The sum calculation unit 207 can use, for example, a value obtained from a Gaussian distribution or a Lorentz distribution with the distance from the end of the diameter of the opening as a variable as the weighting coefficient.

  By calculating the total light emission intensity using the weighting coefficient, the compressive stress value estimation apparatus according to the present embodiment can calculate the magnitude of the light emission intensity involved in the application of compressive stress more accurately. As a result, the compressive stress value estimation apparatus according to the present embodiment can more accurately estimate the magnitude of the applied compressive stress.

  The sum total calculation unit 207 inputs the sum of the light emission intensities calculated using the above formula 1 or the above formula 2 to the stress value estimation unit 209 described later.

The stress value estimation unit 209 is realized by a CPU, a ROM, a RAM, and the like, for example. The stress value estimation unit 209 refers to a database indicating the correlation between the light emission intensity and the compression stress, and estimates the magnitude of the applied compressive stress based on the total light emission intensity calculated by the sum calculation unit 207. More specifically, the stress value estimation unit 209 determines that the sum S _A and S _B of the emission intensities at the points A and B, which are points to be strengthened, from the sum total calculation unit 207 for the periphery of the opening of a certain branch hole. When transmitted, the acquired sums S _A and S _B are compared with the contents of the stress value estimation database registered in advance to estimate the magnitudes of the applied compressive stress values σ _A and σ _B.

  Here, prior to describing the stress value estimation processing by the stress value estimation unit 209, a stress value estimation database used for stress value estimation will be described.

In order to create this stress value estimation database, a laser peening process is performed on an actual common rail in advance using the same apparatus used for the laser peening process (that is, the laser processing apparatus 10 according to the present embodiment). Then, compressive stress is applied to the plurality of branch holes of the common rail. At this time, the compressive stress estimation apparatus 200 measures the light emission amount by the method described above, and calculates S _A and S _B for points A and B near each branch hole. Next, the common rail actually laser-peened is cut and divided, and the X-ray residual stress measurement device is used to increase the compressive stress values σ _A and σ _{B applied to} the points A and B near each branch hole. Measure the thickness. From the above measurement data, a regression line representing the correlation between the total light emission amounts S _A and S _B and the compressive stresses σ _A and σ _B is obtained.

  The compressive stress estimation apparatus 200 records and sets the stress value estimation database created in advance in this manner in the storage unit 211 and the like which will be described later.

In the actual laser peening process for the common rail, the stress value estimation unit 209 is created in advance as described above and recorded in the storage unit 211 as the sum S _A and S _{B of} the emission intensity transmitted from the sum calculation unit 207. The magnitudes of the actually applied stress values σ _A and σ _B are estimated based on the stored database.

When the stress value estimation unit 209 obtains the estimation results of the magnitudes of the compressive stress values σ _A and σ _B , the stress value estimation unit 209 displays the obtained estimation results on a display unit such as a display (see FIG. (Not shown). Thereby, the user of the compressive stress value estimation apparatus 200 (and hence the user of the laser processing apparatus 10) estimates the magnitude of the stress value imparted by the non-destructive laser peening process at the manufacturing site of the common rail. Can do.

Returning to FIG. 8 again, the storage unit 211 according to the present embodiment will be described in detail.
The storage unit 211 stores a database indicating the correlation between the emission intensity and the compressive stress. In the storage unit 211, various history information such as various history information regarding the laser peening processing performed may be recorded. Furthermore, in the storage unit 211, various parameters, processes in progress, or various databases that need to be saved when the compressive stress value estimation apparatus 200 according to the present embodiment performs some processing, or various databases are stored. Are recorded as appropriate. The storage unit 211 can be freely read and written by the measurement data acquisition unit 201, the coordinate data acquisition unit 203, the intensity calculation unit 205, the total calculation unit 207, the stress value estimation unit 209, and the like.

  Heretofore, an example of the function of the compressive stress value estimation apparatus 200 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  A computer program for realizing each function of the compression stress value estimation apparatus according to the present embodiment as described above can be produced and installed in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

<About the estimation method of compressive stress value>
Next, a stress value estimation method performed by the compressive stress value estimation apparatus 200 will be described in detail with reference to FIG. FIG. 14 is a flowchart for explaining the compressive stress value estimation method according to the present embodiment.

  First, the measurement data acquisition unit 201 of the compressive stress value estimation apparatus 200 acquires measurement data related to the amount of light emission generated by the pulsed laser beam applied to the processing target member such as the common rail, from the light emission detection element 119. (Step S101). The measurement data acquisition unit 201 transmits the acquired measurement data to the intensity calculation unit 205.

  Subsequently, the intensity calculation unit 205 calculates the light emission intensity of the light emitted by the pulse laser beam based on the measurement data of the light emission amount transmitted from the measurement data acquisition unit 201 (step S103). The intensity calculation unit 205 transmits the calculated light emission intensity to the total calculation unit 207.

  On the other hand, the coordinate data acquisition unit 203 of the compressive stress value estimation apparatus 200 acquires coordinate data representing the irradiation position of the pulse laser beam transmitted from the irradiation position control apparatus 300 and transmits the coordinate data to the total calculation unit 207. The sum calculation unit 207 calculates the sum of the emission intensities in a predetermined region around the point to be strengthened based on the emission intensity transmitted from the intensity calculation unit 205 and the coordinate data transmitted from the coordinate data acquisition unit 203. (Step S105). The sum total calculation unit 207 transmits the calculated sum of the emission intensity to the stress value estimation unit 209.

  Subsequently, the stress value estimation unit 209 is assigned to the reinforcement target point based on the total sum of the transmitted light emission intensities and the database indicating the correlation between the light emission intensity and the compressive stress stored in the storage unit 211. The magnitude of the compressive stress value is estimated (step S107).

  At the periphery of the opening of the branch hole including the notch called the branch hole and the inclined surface connected to the notch, the amount of light emitted by each pulse laser beam fluctuates when each pulse laser beam is irradiated. Will be. However, in the compressive stress value estimating method performed by the compressive stress value estimating apparatus 200 according to the present embodiment, a predetermined region is set around the point to be strengthened, that is, the opening peripheral portion of the branch hole, and the emission intensity in this region is set. It is possible to accurately estimate the circumferential component of the compressive stress that is locally applied in the vicinity of the point to be strengthened.

(Second Embodiment)
In the compressive stress value estimation apparatus 200 according to the second embodiment of the present invention described below, at the time when the laser peening process to the opening peripheral portion of one branch hole 5 is completed, prior to the process of calculating the light emission amount, The center position of the branch hole 5 is predicted. In the laser peening process to each branch hole 5, the irradiation head 111 is moved to the position of the branch hole 5 by the rotation driving device 113 and the parallel driving device 115, thereby irradiating the pulse laser beam. However, there is a limit to the accuracy of irradiation position setting by driving from the outside via the support rod 109. For example, the accuracy of the set coordinates of the center position of the reference branch hole 5 may be shifted by about 0.1 mm. . Thereby, the irradiation position of each pulse laser beam recorded as a data set based on the coordinates of the rotation driving device 113 and the parallel driving device 115 is 0.1 mm from the position when the position of the true branch hole is taken as a reference. It will deviate to some extent.

  Therefore, in the compressive stress value estimation apparatus 200 according to the present embodiment, a position correction unit that corrects the irradiation position of the pulse laser beam as described below is provided, thereby preventing a decrease in accuracy due to such positional deviation.

<Configuration of compressive stress value estimation device>
Below, the structure of the compressive-stress value estimation apparatus 200 which concerns on this embodiment is demonstrated in detail, referring FIG. FIG. 15 is a block diagram for explaining the configuration of the compressive stress value estimation apparatus 200 according to the present embodiment.

  For example, as shown in FIG. 15, the compressive stress value estimation apparatus 200 according to the present embodiment includes a measurement data acquisition unit 201, a coordinate data acquisition unit 203, an intensity calculation unit 205, a sum calculation unit 207, and a stress value. It mainly includes an estimation unit 209, a storage unit 211, and a position correction unit 251.

  The measurement data acquisition unit 201, the stress value estimation unit 209, and the storage unit 211 according to the present embodiment have the same configuration as each processing unit according to the first embodiment of the present invention and have the same effects. It is. Therefore, in the following, detailed description of each processing unit is omitted.

  The coordinate data acquisition unit 203 according to the present embodiment has the same configuration as the coordinate data acquisition unit 203 according to the first embodiment of the present invention, except that the acquired coordinate data is transmitted to the position correction unit 251. The same effect is produced. Therefore, in the following, detailed description of the coordinate data acquisition unit 203 is omitted.

  The sum total calculation unit 207 according to the present embodiment calculates the total light emission intensity based on the corrected coordinate data transmitted from the position correction unit 251 described later and the light emission intensity transmitted from the intensity calculation unit 205. Other than that, the configuration is the same as that of the sum total calculation unit 207 according to the first embodiment of the present invention, and the same effects are achieved. Therefore, in the following, detailed description of the sum calculation unit 207 is omitted.

  The position correction unit 251 is realized by, for example, a CPU, a ROM, a RAM, and the like. The position correction unit 251 identifies the center position of the branch hole 5 based on the emission intensity distribution calculated by the intensity calculation unit 205, and determines the position irradiated with the pulse laser beam based on the identification result of the center position. Correct the coordinate data to be represented.

  More specifically, the position correction unit 251 uses the fact that the light emission amount for each pulse laser beam is the weakest at the center of the branch hole 5, and thereby the light emission amount for a plurality of pulse laser beams irradiated near the branch hole. The center position coordinates of the branch hole are predicted from the distribution.

  Therefore, the position correction unit 251 first considers the positional relationship between the irradiation positions of a plurality of pulse laser beams based on the emission intensity acquired from the intensity calculation unit 205 and the coordinate data acquired from the coordinate data acquisition unit 203. Then, the distribution of emission intensity is calculated. Subsequently, the position correction unit 251 refers to the calculated emission intensity distribution and specifies coordinates that give the minimum value of the emission intensity. The position correction unit 251 calculates the amount of deviation from the center position of the true branch hole from the specified coordinate data, and corrects all the coordinate data acquired from the coordinate data acquisition unit 203 based on the calculated amount of deviation. Thereafter, the position correction unit 251 transmits the corrected coordinate data to the total calculation unit 207 together with the light emission intensity.

The sum total calculation unit 207 according to the present embodiment calculates the sum of the light emission intensities using the coordinate data corrected by the position correction unit 251, thereby improving the accuracy of the calculated sums S _A and S _B of the light emission intensities. Is possible. Accordingly, the stress value estimation unit 209 according to the present embodiment can improve the estimation accuracy of the compressive stress values σ _A and σ _B by using the total sum S _A and S _B of the emission intensity with improved accuracy.

  Heretofore, an example of the function of the compressive stress value estimation apparatus 200 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  A computer program for realizing each function of the compression stress value estimation apparatus according to the present embodiment as described above can be produced and installed in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

<About the estimation method of compressive stress value>
Next, a compression stress value estimation method performed by the compression stress value estimation apparatus 200 according to the present embodiment will be described in detail with reference to FIG. FIG. 16 is a flowchart for explaining the compressive stress value estimation method according to this embodiment.

  First, the measurement data acquisition unit 201 of the compressive stress value estimation apparatus 200 acquires measurement data related to the amount of light emission generated by the pulsed laser beam applied to the processing target member such as the common rail, from the light emission detection element 119. (Step S101). The measurement data acquisition unit 201 transmits the acquired measurement data to the intensity calculation unit 205.

  Subsequently, the intensity calculation unit 205 calculates the light emission intensity of the light emitted by the pulse laser beam based on the measurement data of the light emission amount transmitted from the measurement data acquisition unit 201 (step S103). The intensity calculation unit 205 transmits the calculated light emission intensity to the position correction unit 251.

  On the other hand, the coordinate data acquisition unit 203 of the compressive stress value estimation apparatus 200 acquires coordinate data representing the irradiation position of the pulse laser beam transmitted from the irradiation position control apparatus 300 and transmits the coordinate data to the position correction unit 251. The position correction unit 251 considers the positional relationship between the irradiation positions of the plurality of pulse laser beams based on the emission intensity transmitted from the intensity calculation unit 205 and the coordinate data transmitted from the coordinate data acquisition unit 203. Accordingly, the distribution of the emission intensity is calculated, and the coordinates giving the minimum value of the emission intensity are specified. The position correction unit 251 calculates the amount of deviation from the center position of the true branch hole from the specified coordinate data, and corrects all the coordinate data acquired from the coordinate data acquisition unit 203 based on the calculated amount of deviation ( Step S151).

  When the correction of the coordinate data is completed, the position correction unit 251 transmits the corrected coordinate data and the total light emission intensity to the total calculation unit 207. Based on the transmitted light emission intensity and the corrected coordinate data, the sum total calculation unit 207 calculates the total light emission intensity in a predetermined region around the reinforcement target point (step S105). The sum total calculation unit 207 transmits the calculated sum of the emission intensity to the stress value estimation unit 209.

  Subsequently, the stress value estimation unit 209 is assigned to the reinforcement target point based on the total sum of the transmitted light emission intensities and the database indicating the correlation between the light emission intensity and the compressive stress stored in the storage unit 211. The magnitude of the compressive stress value is estimated (step S107).

  In the stress value estimation method performed by the compressive stress value estimation apparatus 200 according to the present embodiment, the accurate center position of the branch hole 5 is specified based on the emission intensity distribution, whereby the sum of the emission intensity is more accurately determined. It is possible to calculate. Thereby, in the stress value estimation method according to the present embodiment, it is possible to more accurately estimate the circumferential component of the compressive stress locally applied in the vicinity of the point to be strengthened.

(About hardware configuration)
Next, a hardware configuration of the compressive stress value estimation apparatus 200 according to the embodiment of the present invention will be described in detail with reference to FIG. FIG. 17 is a block diagram for explaining a hardware configuration of the compressive stress value estimation apparatus 200 according to the embodiment of the present invention.

  The compressive stress value estimation apparatus 200 mainly includes a CPU 901, a ROM 903, and a RAM 905. The compressive stress value estimation device 200 further includes a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

  The CPU 901 functions as an arithmetic processing unit and a control unit, and controls all or a part of the operation in the compression stress value estimation device 200 according to various programs recorded in the ROM 903, the RAM 905, the storage device 913, or the removable recording medium 921. To do. The ROM 903 stores programs used by the CPU 901, calculation parameters, and the like. The RAM 905 primarily stores programs used in the execution of the CPU 901, parameters that change as appropriate during the execution, and the like. These are connected to each other by a bus 907 constituted by an internal bus such as a CPU bus.

  The bus 907 is connected to an external bus such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge.

  The input device 909 is an operation unit operated by the user, such as a mouse, a keyboard, a touch panel, a button, a switch, and a lever. The input device 909 may be, for example, remote control means (so-called remote control) using infrared rays or other radio waves, or an external connection device 923 such as a PDA corresponding to the operation of the compressive stress value estimation device 200. It may be. Furthermore, the input device 909 includes, for example, an input control circuit that generates an input signal based on information input by a user using the operation unit and outputs the input signal to the CPU 901. A user of the compressive stress value estimating apparatus 200 can input various data and instruct a processing operation to the compressive stress value estimating apparatus 200 by operating the input device 909.

  The output device 911 is configured by a device that can notify the user of the acquired information visually or audibly. Examples of such devices include CRT display devices, liquid crystal display devices, plasma display devices, EL display devices and display devices such as lamps, audio output devices such as speakers and headphones, printer devices, mobile phones, and facsimiles. The output device 911 outputs results obtained by various processes performed by the compressive stress value estimation device 200, for example. Specifically, the display device displays the results obtained by the various processes performed by the compressive stress value estimation device 200 as text or an image. On the other hand, the audio output device converts an audio signal composed of reproduced audio data, acoustic data, and the like into an analog signal and outputs the analog signal.

  The storage device 913 is a data storage device configured as an example of a storage unit of the compressive stress value estimation device 200. The storage device 913 includes, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. The storage device 913 stores programs executed by the CPU 901, various data, various data acquired from the outside, and the like.

  The drive 915 is a recording medium reader / writer, and is built in or externally attached to the compressive stress value estimation apparatus 200. The drive 915 reads information recorded on a removable recording medium 921 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 905. The drive 915 can also write a record on a removable recording medium 921 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. The removable recording medium 921 is, for example, a CD medium, a DVD medium, a Blu-ray medium, or the like. The removable recording medium 921 may be a CompactFlash (registered trademark) (CompactFlash: CF), a flash memory, an SD memory card (Secure Digital memory card), or the like. Further, the removable recording medium 921 may be, for example, an IC card (Integrated Circuit card) on which a non-contact IC chip is mounted, an electronic device, or the like.

  The connection port 917 is a port for directly connecting a device to the compressive stress value estimation apparatus 200. Examples of the connection port 917 include a USB (Universal Serial Bus) port, an IEEE 1394 port, a SCSI (Small Computer System Interface) port, and an RS-232C port. By connecting the external connection device 923 to the connection port 917, the compressive stress value estimation apparatus 200 acquires various data directly from the external connection device 923 or provides various data to the external connection device 923. .

  The communication device 919 is a communication interface configured with, for example, a communication device for connecting to the communication network 925. The communication device 919 is, for example, a communication card for wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), or WUSB (Wireless USB). The communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), or a modem for various communication. The communication device 919 can transmit and receive signals and the like according to a predetermined protocol such as TCP / IP, for example, with the Internet and other communication devices. The communication network 925 connected to the communication device 919 is configured by a wired or wireless network, and may be, for example, the Internet, a home LAN, infrared communication, radio wave communication, satellite communication, or the like. .

  Heretofore, an example of the hardware configuration capable of realizing the function of the compressive stress value estimation apparatus 200 according to the embodiment of the present invention has been shown. Each component described above may be configured using a general-purpose member, or may be configured by hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration to be used as appropriate according to the technical level at the time of carrying out this embodiment.

  The hardware configuration of the irradiation position control device 300 according to the embodiment of the present invention is the same as the hardware configuration of the compression stress value estimation device 200 according to the embodiment of the present invention, and has the same effects. Therefore, explanation is omitted.

(Example)
Next, in order to verify the effect of the present invention, the results of investigating the correlation between the total light emission amounts S _A and S _B and the compressive stress values σ _A and σ _B will be described in detail.

First, using the laser processing apparatus 10 including the compressive stress value estimation apparatus 200 according to the embodiment of the present invention shown in FIG. 4 with respect to the periphery of the five branch hole openings of the common rail 1 shown in FIG. Laser peening treatment was performed. The common rail 1 was manufactured using a steel material having a tensile strength of 600 MPa. Inside diameter _{d 1} of the rail hole 4 is 10 mm, the inner diameter _{d 2} of the branch hole 5 was 1 mm. Further, in order to alleviate the stress concentration around the opening of the branch hole 5, electrolytic polishing as shown in FIG. 3 was performed.

  As a laser beam, a double wave (wavelength 532 nm) of an Nd: YAG laser having high permeability in water was used, the pulse energy was 100 mJ, and the pulse width was 10 ns. The spot diameter of the laser beam was 0.6 mm, and the pulse repetition frequency was 100 Hz.

  The laser peening process was performed on a 4 mm square region with the center position of the branch hole 5 as the center. In order to increase the compressive stress in the circumferential direction of the branch hole in the vicinity of the point A and the point B near the branch hole opening, the beam spot is scanned in a direction parallel to the axial direction of the rail hole 4 as shown in FIG. The processing was performed by scanning the beam spot a plurality of times while shifting the position in the circumferential direction of the rail hole 4. The average value of the number of times of irradiation with the pulse laser beam for the same point was 25 times.

  Further, a photodiode was used as the light emission detecting element 119, and the amount of light emission with respect to irradiation of each pulse laser beam being processed was measured and recorded by this photodiode. Further, as the optical filter 121, a laser light cut filter for blocking reflected light and stray light from the processing point of the processing laser beam was used. Conversion from the light emission amount to the light emission intensity was performed by time-integrating the time waveform of light emission shown in FIG. 10 for each laser pulse. After the processing for one branch hole was completed, as shown in Examples 1 to 3 below, an operation for calculating the sum by the above-described plurality of methods was performed.

Further, in Examples 1 to 3 below, branch hole circumferential stresses σ _A and σ _B at points A and B near each branch hole were measured. For the stress measurement at the points A and B, a part including the branch hole 5 was cut out and measured using an X-ray residual stress measuring apparatus. In this cutting process, cutting was performed at a position away from the opening on the rail hole 4 side of the branch hole 5 so that the residual stress applied by the laser peening process did not change. The cut-out size was such that the length of the rail hole 4 in the axial direction was 40 mm, and the rail hole 4 was cut by a plane perpendicular to the axis of the branch hole 5 and including the axis of the rail hole 4. The beam diameter in the X-ray stress measurement was 0.1 mm.

The relationship between the sum S _A and S _{B of} the luminescence intensity obtained as described above and the residual stresses σ _A and σ _B is plotted on a graph, and the estimation accuracy is determined by the variation from the regression line approximated by a quadratic curve. Evaluated. Hereinafter, details of the calculation method in each embodiment will be described.

<Example 1>
In the first embodiment, light emission is performed by calculating the sum of the corresponding emission intensities I based on Equation 1 above for a pulse laser beam irradiated to a predetermined range in the vicinity of points A and B, which are points to be enhanced. The sum of the strengths S _A and S _B was calculated. The range in which the total is taken into consideration is based on the stress distribution generated by one pulse laser beam as described above, as shown by the hatched portion in FIG. 12, the major axis U _R = 1.5 mm around the point A and the point B, and the minor axis An elliptical shape with U _Z = 1.0 mm was adopted.

  The results are shown in FIG. In FIG. 18, there are five branch holes for one common rail, data for points A and B on both sides of each hole is shown, and the total number of data is 10. As is clear from FIG. 18, a positive correlation is found between the sum S of the emission intensity and the applied stress value σ, and the applied stress is calculated by calculating the sum S of the emission intensity. It can be seen that the value σ can be estimated. It was 47 MPa when the average value of the difference between the stress value actually applied and the stress expected from the value of the regression line was calculated based on the following Equation 3.

・・・（式３）

... (Formula 3)

<Example 2>
In the second embodiment, the range in which the sum is taken into consideration is the same as in the first embodiment shown in FIG. In the present embodiment, the weighting calculation based on the above-described equation 2 was performed on the assumption that the pulse laser beam irradiated near the points A and B, which are points to be strengthened, has a larger contribution. The weighting coefficient used for the calculation was a value calculated from a Gaussian distribution represented by the following Equation 4 in consideration of the extent of the shape of the stress distribution shown in FIG.

・・・（式４）

... (Formula 4)

  Here, in the above equation 4, the parameter r is the separation distance from the point A or B of the irradiation position of each pulse laser beam. The obtained result is shown in FIG. In FIG. 19, the total number of data is 10 as in the case of the first embodiment. It was 33 MPa when the average value of the difference between the stress value actually applied and the stress expected from the value of the regression line was calculated based on the above formula 3. This result shows that the estimation error of the stress value can be made smaller than that in the first embodiment by using such a sum total calculation method.

<Example 3>
The third embodiment is the same as the second embodiment in that a range that takes the summation into account and a weighting operation are used. In the third embodiment, the center position coordinate of the branch hole is specified from the distribution of the emission intensity with respect to the plurality of pulse laser beams irradiated near the branch hole, and the irradiation position of each pulse laser beam is determined based on this specification result. A method of calculating the total emission intensity after correcting the above was used.

The center position of the branch hole is specified by using a drop in the emission intensity with respect to the irradiation of the pulse laser beam in which the center position of the spot diameter enters the branch hole. Specifically, the spatial distribution of the emission intensity of the pulsed laser beam irradiated to a region having a radius of 0.5 mm or less centered on the point set as the center of the branch hole before the laser peening process is a quadratic convex downward The surface was approximated by a curved surface, and the bottom point of the resulting quadric surface was redefined as the center of the branch hole. Based on the redefinition results of the center position coordinates of the branch holes, the irradiation position coordinates of each pulse laser beam were corrected, and then the total emission intensity S _A and S _B was calculated.

  The results are shown in FIG. When the average value of the difference between the stress value actually applied and the stress expected from the value of the regression line was calculated based on the above equation 3, it was 20 MPa. This result shows that the estimation error of the stress value can be made smaller than that in the second embodiment by using such a sum calculation method.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Laser processing apparatus 100 Laser irradiation apparatus 200 Compression stress value estimation apparatus 201 Measurement data acquisition part 203 Coordinate data acquisition part 205 Strength calculation part 207 Sum total calculation part 209 Stress value estimation part 211 Storage part 251 Position correction part 300 Irradiation position control apparatus 301 Drive control unit 303 Coordinate data acquisition unit 305 Coordinate data transmission unit 400 Water supply pump

Claims (16)

In a laser peening process in which a member to be processed having an opening is irradiated with a pulse laser beam and compressive stress is applied to the member to be processed, the compressive stress applied to the member to be processed is estimated. And
Obtaining a measurement result of a light emission amount, which is time waveform data of light generated by irradiating a plurality of pulse laser beams on the periphery of the opening of the member to be processed;
Calculating, based on the emission intensity is the peak value or the time integral value of the emission amount of the light generated near the ends of the diameter of the opening, the light emission amount of the measurement results,
Referring to a preset database showing the correlation between the luminescence intensity and the compressive stress, and estimating the magnitude of the applied compressive stress based on the calculated luminescence intensity;
Only including,
In the step of calculating the light emission intensity, the light emission amount of light emission in a region centering on an end portion of the diameter of the opening is specified from the measurement result of the light emission amount, and the sum of the light emission intensities in the region. A method for estimating a compressive stress value. In the step of calculating the light emission intensity, the light emission amount of light emission in an elliptical region centering on an end of the diameter of the opening is specified from the measurement result of the light emission amount, and light emission is performed in the region. calculating the sum of the intensity, the method of estimating the compression stress value of claim 1. A plurality of the openings are provided along the longitudinal direction of the member to be processed.
The method for estimating a compressive stress value according to claim 2 , wherein a major axis direction of the elliptical region is a direction orthogonal to a longitudinal direction of the member to be processed. In the step of calculating the light emission intensity, the weighting coefficient corresponding to the distance from the end of the diameter of the opening is added to each of the light emission intensities included in the region to calculate the total light emission intensity. The method for estimating a compressive stress value according to claim 1 . The compressive stress value estimation method according to claim 4 , wherein the weighting coefficient is a value obtained from a Gaussian distribution using a distance from an end of the diameter of the opening as a variable. Between the step of calculating the light emission intensity and the step of estimating the magnitude of the compressive stress, the center position of the opening is specified based on the distribution of the light emission intensity, and the center position is determined based on the determination result of the center position. The method for estimating a compressive stress value according to claim 1, further comprising a step of correcting information representing a position irradiated with the pulse laser beam. In the step of correcting the information indicating the position where the pulsed laser beam is irradiated, the position giving the minimum value of the emission intensity in the distribution of the luminous intensity, is specified as the central position of the opening, according to claim 6 Method for estimating the compressive stress value . In a laser peening process in which a processing member having an opening is irradiated with a pulsed laser beam and compressive stress is applied to the processing target member, a compressive stress value for estimating the compressive stress applied to the processing target member An estimation device,
A measurement data acquisition unit that acquires measurement data related to the amount of light emission, which is time waveform data of light generated by irradiating a plurality of pulsed laser beams to the periphery of the opening of the member to be processed;
Based on the measurement data related to the light emission amount, an intensity calculation unit that calculates a light emission intensity that is a peak value or a time integral value of the light emission amount from the light emission amount ;
A sum total calculation unit for calculating the sum of the emission intensity of light generated near both ends of the diameter of the opening based on the emission intensity calculated by the intensity calculation unit;
A stress value estimation unit that estimates a magnitude of the applied compressive stress based on a total sum of the emission intensities calculated by the total calculation unit with reference to a preset database showing a correlation between the emission intensity and the compression stress; ,
A coordinate data acquisition unit for acquiring coordinate data which is data representing the irradiation position of the pulse laser beam;
Equipped with a,
The said sum total calculation part is a compressive-stress value estimation apparatus which calculates the sum total of the emitted light intensity of the light generate | occur | produced near the both ends of the diameter of the said opening part based on the said coordinate data . The compressive stress value estimation apparatus according to claim 8 , wherein the total calculation unit calculates a total sum of light emission intensities in a region centered on an end of a diameter of the opening. The compressive stress value estimation apparatus according to claim 9 , wherein the total calculation unit calculates a total sum of light emission intensities in an elliptical region centered on an end of a diameter of the opening. A plurality of the openings are provided along the longitudinal direction of the member to be processed.
The compressive stress value estimation apparatus according to claim 10 , wherein the total calculation unit sets a major axis direction of the elliptical region as a direction orthogonal to a longitudinal direction of the processing target member. The sum total calculation unit calculates a sum of emission intensities by adding a weighting coefficient corresponding to a distance from an end of a diameter of the opening to each of the emission intensities included in the region. 9. The compressive stress value estimation apparatus according to 9 . The compressive stress value estimation apparatus according to claim 12 , wherein the total calculation unit uses a value obtained from a Gaussian distribution having a distance from an end of a diameter of the opening as a variable as the weighting coefficient. The compressive stress value estimation device identifies the center position of the opening based on the emission intensity distribution calculated by the intensity calculation unit, and the pulse laser beam is irradiated based on the identification result of the center position. The compressive-stress value estimation apparatus of Claim 8 further provided with the position correction part which correct | amends the coordinate data showing a position. The compression stress value estimation device according to claim 14 , wherein the position correction unit specifies a position that gives a minimum value of light emission intensity in the light emission intensity distribution as a center position of the opening. A laser processing apparatus capable of executing a laser peening process for irradiating a member to be processed having an opening with a pulsed laser beam and applying a compressive stress to the member to be processed,
A laser beam oscillator that irradiates the target member with a pulse laser beam of a predetermined wavelength, and a light generated by irradiating the peripheral portion of the opening of the target member with a plurality of pulse laser beams and the irradiation of the pulse laser beam. A laser irradiation apparatus comprising: an irradiation head that collects light; and a detection element that detects light generated by the irradiation of the pulse laser beam;
The compressive stress value estimation apparatus according to any one of claims 8 to 15 ,
A laser processing apparatus comprising:

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