阅读说明：本技术 激光喷丸加工装置 (Laser shot-peening device ) 是由 中野麻由 足立隆史 于 2018-04-04 设计创作，主要内容包括：实施方式所涉及的激光喷丸加工装置,具备振荡出激光的激光振荡器和通过透镜将所述激光聚光并照射于被加工物的照射系统,所述照射系统构成为在不经由液体而露出于大气中的状态下对所述被加工物照射所述激光。另外,实施方式所涉及的激光喷丸加工方法,是通过使用所述的激光喷丸加工装置进行所述被加工物的激光喷丸加工来制造成品或者半成品的方法。(A laser peening apparatus according to an embodiment includes a laser oscillator that oscillates a laser beam, and an irradiation system that condenses the laser beam through a lens and irradiates the laser beam onto a workpiece, and the irradiation system is configured to irradiate the workpiece with the laser beam in a state of being exposed to the atmosphere without passing through a liquid. In addition, the laser peening method according to the embodiment is a method of manufacturing a finished product or a semi-finished product by performing laser peening of the workpiece using the laser peening apparatus.)

1. A laser peening apparatus includes:

a laser oscillator that oscillates laser light; and

an irradiation system for condensing the laser beam through a lens and irradiating the laser beam onto a workpiece,

the irradiation system is configured to irradiate the laser beam to the workpiece in a state of being exposed to the atmosphere without passing through a liquid.

2. The laser peening apparatus according to claim 1, wherein,

the laser oscillator is a femtosecond laser oscillator that oscillates femtosecond laser light.

3. The laser peening apparatus according to claim 1 or 2, wherein,

the illumination system has:

a cylindrical nozzle having one open end connected to the laser oscillator and made of a light shielding material for shielding scattered light of the laser beam; and

and an elastic body attached to the other opening end of the nozzle and configured to slide while contacting a surface of the workpiece.

4. The laser peening apparatus according to claim 3, wherein,

further provided with:

a sensor that detects a contact state between the elastic body and the workpiece; and

and a control device that stops the oscillation of the laser light by controlling a power supply of the laser oscillator in accordance with the contact state.

5. The laser peening apparatus according to any one of claims 1 to 4,

the laser processing apparatus further includes a dust collector for collecting debris of the workpiece generated by the irradiation of the laser beam.

6. The laser peening apparatus according to claim 3 or 4, wherein,

further provided with:

a dust collector for collecting debris of the workpiece generated in the nozzle by the irradiation of the laser beam; and

a connection pipe for connecting the dust collector and the suction nozzle,

the nozzle side of the connecting pipe is connected to a groove formed on the workpiece side of the annular elastic body or a through hole formed in the elastic body.

7. The laser peening apparatus according to claim 6, wherein,

an air intake port for taking in air for recovering the debris into the nozzle is formed in the nozzle, and the scattered light of the laser light does not leak to the outside of the nozzle.

8. The laser peening apparatus according to any one of claims 1 to 7,

the elastomer is composed of at least one of polytetrafluoroethylene, polyamide resin, and polyacetal resin.

9. A laser peening method, wherein,

the laser peening method is used for manufacturing a finished product or a semi-finished product by performing laser peening of the workpiece by using the laser peening apparatus according to any one of claims 1 to 8.

Technical Field

Embodiments of the present invention relate to a laser peening apparatus and a laser peening method.

Background

Conventionally, laser peening has been known as a method for modifying the surface of an object by applying residual stress thereto. Typically, laser peening is performed by converging a laser beam on a surface to be processed of a workpiece in a state of being covered with a liquid. If the laser beam is condensed and irradiated to the surface to be processed of the object to be processed covered with the liquid, the plasma generated by the irradiation of the laser beam can be confined in the liquid. As a result, the pressure of the shock wave is applied to the workpiece surface. This allows the compressive stress generated in the workpiece to remain as residual stress.

As a specific example, a portable laser peening apparatus has been proposed which can supply water to a cylindrical body having a diameter of 40mm and a length of 200mm so as to perform laser peening without immersing a workpiece in water (see, for example, patent document 1). Further, there has been proposed an apparatus for performing laser peening without using a liquid by performing pulse irradiation of a laser beam through a covering member while sliding the covering member having a solid transparent layer (see, for example, patent document 2).

Patent document 1: japanese patent laid-open publication No. 2010-247213

Patent document 2: japanese patent laid-open No. 2014-176870

Disclosure of Invention

The invention aims to reduce the limitation on the working environment required for laser peening.

The laser peening apparatus according to an embodiment of the present invention includes: a laser oscillator that oscillates laser light; and an irradiation system configured to irradiate the workpiece with the laser light while condensing the laser light by a lens, the irradiation system being configured to irradiate the workpiece with the laser light in a state of being exposed to the atmosphere without passing through a liquid.

In addition, the laser peening method according to the embodiment of the present invention is a method for manufacturing a finished product or a semi-finished product by performing laser peening of the workpiece using the laser peening apparatus.

Drawings

Fig. 1 is a configuration diagram of a laser peening apparatus according to an embodiment of the present invention.

Fig. 2 is an enlarged sectional view of the front end portion of the nozzle shown in fig. 1.

Fig. 3 is a bottom view of the elastic body shown in fig. 2.

Fig. 4 is a front view showing another configuration example of the elastic body shown in fig. 1 to 3.

Fig. 5 is an enlarged sectional view showing the structure of the air intake port shown in fig. 1.

Fig. 6 is a right side view of the air intake port shown in fig. 4.

Detailed Description

A laser peening apparatus and a laser peening method according to an embodiment of the present invention will be described with reference to the drawings.

(Structure and function)

Fig. 1 is a configuration diagram of a laser peening apparatus according to an embodiment of the present invention.

The laser peening apparatus 1 is an apparatus that performs laser peening of a workpiece W in a state of being exposed to the atmosphere without passing through a liquid. Therefore, the laser peening apparatus 1 includes a laser oscillator 2 that oscillates a laser beam L, an irradiation system 3 that irradiates the laser beam L on a workpiece W, a power supply 4 that supplies power to the laser oscillator 2, a control device 5 that controls the power supply 4, and a dust collector 6 that collects debris of the workpiece W generated by laser peening.

The irradiation system 3 is configured to irradiate the workpiece W with the laser light L in a state of being exposed to the atmosphere without passing through a liquid. Therefore, the irradiation system 3 can be formed into a simple configuration in which the lens 7 is disposed inside the nozzle 8. The lens 7 is an optical element for condensing the laser light L oscillated by the laser oscillator 2 and irradiating the same onto the workpiece W.

In order to perform laser peening of the workpiece W in a state of being exposed to the atmosphere, it is a condition that the laser light L has sufficient intensity. When the pulse energy is E, the area of a beam spot (beam spot) to which the pulse laser light is irradiated is S, and the pulse width is t, the intensity I of the pulse laser light is represented by I ═ E/(S · t). Therefore, even if the pulse energy E is constant, if the pulse width t becomes small, the intensity I of the pulse laser light becomes large.

Picosecond lasers or femtosecond lasers with a pulse width t less than or equal to several picoseconds are called ultrashort pulses. In ultrashort pulses, in particular femtosecond lasers with a pulse width t on the order of femtoseconds (1000 msec) and Nd: unlike nanosecond laser light such as YAG laser light, laser peening of a workpiece W is performed in the air without passing through a liquid such as water, and has a sufficient intensity I.

Therefore, it is practical to configure the laser oscillator 2 with a femtosecond laser oscillator that oscillates a femtosecond laser beam as the laser beam L. However, when the intensity I of the pulse laser beam required for laser peening is small, the laser oscillator 2 may be configured by a picosecond laser oscillator. The object of laser peening is a plastically deformed metal such as aluminum, iron, titanium, or the like. Therefore, the intensity I of the pulsed laser beam required for laser peening is determined according to the material to be subjected to laser peening. Next, a case where the laser oscillator 2 is constituted by a femtosecond laser oscillator will be mainly described.

Oscillating Nd: a conventional nanosecond laser oscillator such as a YAG laser has a large size of about 1m in length and also about 50kg in weight. Therefore, when laser peening is performed using a nanosecond laser oscillator, it is practical to fix the nanosecond laser oscillator and move the workpiece while holding the workpiece by a robot or the like.

In contrast, if a femtosecond laser oscillator having a length of about 600mm is used, the laser peening apparatus 1 may be a device held by an operator. That is, it is realistic that the operator performs the laser peening of the workpiece W while moving the laser oscillator 2 to which the irradiation system 3 including the lens 7 and the nozzle 8 is connected by hand. Alternatively, it is also practical to mount the laser oscillator 2 to which the irradiation system 3 is connected to the arm of the robot and perform laser peening while moving the irradiation system 3.

Therefore, even if the workpiece W is large as in an aircraft structure, the laser peening can be easily performed with the nozzle 8 directed toward the workpiece W. That is, laser peening can be easily performed in a state where the workpiece W is fixed.

Further, if the laser oscillator 2 is constituted by a femtosecond laser oscillator or the like as described above, a liquid such as water or a coating layer necessary for laser peening treatment is not necessary. Therefore, a device for supplying liquid, which is required in the case of performing laser peening using a nanosecond laser oscillator, is not required.

On the other hand, in the case of the laser peening apparatus 1 configured by a femtosecond laser oscillator or the like, it is important to ensure safety because the intensity of the laser light L is large. That is, it is important to shield the laser light L so that the laser light L and the scattered light of the laser light L do not enter the eyes of the operator. In particular, when the laser peening apparatus 1 is portable, the tip of the nozzle 8 may be oriented in various directions. Therefore, it is necessary that the laser light L does not directly enter the human eye.

Therefore, the nozzle 8 can be formed of a cylindrical light blocking material in order to block the scattered light of the laser light L. As an example of the light shielding material, light aluminum can be given. One open end of the nozzle 8 can be connected to the laser oscillator 2. An elastic body 9 that slides in contact with the surface of the workpiece W can be attached to the other opening end of the nozzle 8.

This allows the optical path of the laser beam L including the construction point of the laser peening to be completely blocked by the nozzle 8. As a result, the laser light L and the scattered light of the laser light L can be prevented from entering the eyes of the operator. Further, since the elastic body 9 is attached to the tip of the workpiece W of the nozzle 8, damage to the workpiece W can be avoided. That is, the laser light L, the reflected light, and the scattered light can be sealed in the nozzle 8 without damaging the workpiece W.

However, if the laser light L is irradiated in a state where a gap is formed between the workpiece W and the elastic body 9, there is a possibility that scattered light or reflected light of the laser light L leaks from the gap. Therefore, the sensor 10 for detecting the contact state between the elastic body 9 and the workpiece W can be provided in the laser peening apparatus 1.

As practical examples of the sensor 10 for detecting the contact state between the elastic body 9 and the workpiece W, a pressure sensor and an optical position sensor are given. For example, when an optical position sensor is used, whether or not the elastic body 9 is in close contact with the surface of the workpiece W can be detected by detecting the distance from the surface of the workpiece W to the elastic body 9. On the other hand, if the pressure sensor 10A is used as shown in the figure, it is possible to detect whether or not the elastic body 9 is in close contact with the surface of the workpiece W by detecting the pressure applied to the elastic body 9 from the surface of the workpiece W.

Since the nozzle 8 is cylindrical, the elastic body 9 is preferably formed in an O-ring shape in order to completely suppress the occurrence of a gap with the workpiece W. Therefore, the O-ring-shaped pressure sensor 10A can be provided between the O-ring-shaped elastic body 9 and the tip of the nozzle 8. Thus, when the elastic body 9 is in contact with the workpiece W, the pressure applied to the elastic body 9 from the workpiece W can be detected by the pressure sensor 10A.

In a case where importance is attached to a simple configuration of the pressure sensor 10A, the pressure sensor 10A can be attached to the tip of the nozzle 8, and the pressure sensor 10A can output the pressure of the annular region in the optical axis direction of the laser light L as a single component. In this case, by performing threshold processing on the measurement value of the pressure output from the pressure sensor 10A, it is possible to detect whether or not the elastic body 9 is in contact with the surface of the workpiece W.

On the other hand, when importance is attached to detecting whether or not the annular elastic body 9 is reliably in close contact with the surface of the workpiece W, the pressure sensor 10A that detects the pressure at least 3 different points of the elastic body 9 can be attached to the tip of the nozzle 8. In this case, by performing threshold processing on the measured values of the pressure at least 3 points, it is possible to detect whether or not the elastic body 9 is completely adhered to the surface of the workpiece W. That is, it can be determined that the elastic body 9 is completely in close contact with the surface of the workpiece W only when the measured values of the pressure at least 3 points of the elastic body 9 are all equal to or greater than the threshold value or exceed the threshold value.

Therefore, the elastic body 9 is required to have characteristics of transmitting pressure to the pressure sensor 10A in addition to lubricity with the workpiece W and elasticity of the surface for contact with the workpiece W. In particular, since the surface of the workpiece W is cleaned before the laser peening, it is important to ensure lubricity with the workpiece W.

Examples of the material of the elastic body 9 satisfying the above requirements include Polytetrafluoroethylene (PTFE), polyamide resin (nylon), and polyacetal resin. The elastic body 9 may be made of a plurality of materials, not a single material. That is, the elastic body 9 may be formed of a laminate material in which a plurality of materials are stacked. Therefore, the elastic body 9 may be composed of at least one of polytetrafluoroethylene, polyamide resin, and polyacetal resin.

The output side of the sensor 10 such as the pressure sensor 10A can be connected to the control device 5 for controlling the power supply 4. In this way, the control device 5 can automatically determine the contact state between the elastic body 9 and the workpiece W, such as whether the elastic body 9 is in contact with the workpiece W or whether the annular elastic body 9 is completely in close contact with the surface of the workpiece W.

Then, the oscillation of the laser light L can be stopped by controlling the power supply 4 of the laser oscillator 2 in accordance with the contact state between the elastic body 9 and the workpiece W. That is, when it is determined that the elastic body 9 is not in contact with the workpiece W or when it is determined that the elastic body 9 is not in complete close contact with the surface of the workpiece W, the power supply 4 of the laser oscillator 2 can be automatically switched off so that the reflected light or scattered light of the laser light L does not leak from the gap between the elastic body 9 and the workpiece W.

In this case, the control device 5 may be configured by an electronic circuit that reads a signal processing program for determining the contact state between the elastic body 9 and the workpiece W based on the detection signal output from the sensor 10 and generating a control signal for switching the power supply 4 of the laser oscillator 2 off in accordance with the determination result.

As another example, in the case where the possibility of an accident occurring immediately even if a gap is generated between the elastic body 9 and the workpiece W is low, such as the case where the nozzle 8 is held by a robot arm, the result of the determination of the contact state between the elastic body 9 and the workpiece W may be displayed on a display device or may be notified to the user of the laser peening apparatus 1 only by a sound or a lamp.

By using such a safety measure of the sensor 10, it is possible to reliably prevent an accident in which not only the laser light L but also the reflected light or the scattered light of the laser light L enters the eyes of a person.

If the laser peening of the workpiece W is performed by irradiating the workpiece W with the laser light L, a part of the workpiece W is generated as debris. In the case of laser peening in liquid as in the related art, debris of the workpiece W is removed by the flow of the liquid, but in the case of laser peening without using liquid, it is important to remove debris of the workpiece W. In particular, when the optical path of the laser beam L is sealed by the nozzle 8, it is important that the laser beam L is blocked without the debris of the workpiece W staying at the working point in the nozzle 8.

Therefore, it is appropriate to collect the dust of the workpiece W generated in the nozzle 8 by the irradiation of the laser light L by the dust collector 6. The dust collector 6 and the nozzle 8 can be connected by a connecting pipe 11. The connecting pipe 11 may be a metal or rubber pipe.

Fig. 2 is an enlarged sectional view of the front end portion of the nozzle 8 shown in fig. 1, and fig. 3 is a bottom view of the elastic body 9 shown in fig. 2.

From the viewpoint of irradiating the laser beam L of an appropriate intensity onto the surface of the workpiece W, it is preferable that the debris of the workpiece W, which may be an obstacle to the laser beam L, does not fly in the nozzle 8. Therefore, the elastic body 9 can be coupled to the coupling pipe 11 as close as possible to the surface of the workpiece W. Therefore, the groove 9A for sucking the debris of the workpiece W from the inside of the nozzle 8 can be formed on the workpiece W side of the elastic body 9. The groove 9A formed in the elastic body 9 is intended to communicate the inside and outside of the nozzle 8, and therefore the longitudinal direction of the groove 9A is the radial direction of the elastic body 9.

The nozzle 8 side of the connecting pipe 11 can be connected to the groove 9A formed on the workpiece W side of the annular elastic body 9. If the connecting pipe 11 is made of rubber, the distal end of the connecting pipe 11 can be bonded to the elastic body 9 with an adhesive, for example. Further, if the connecting pipe 11 is made of metal, the distal end of the connecting pipe 11 can be connected to the elastic body 9 by a fastener such as a screw, for example.

In the illustrated example, two grooves 9A are formed in the elastic body 9 on both sides across the irradiation point of the laser light L. Therefore, the two grooves 9A of the elastic body 9 are connected to the dust collector 6 by the two connecting pipes 11. In this way, from the viewpoint of preventing the debris of the workpiece W from passing through the vicinity of the working point of the laser peening, it is preferable that at least two grooves 9A be provided at equal intervals in the elastic body 9. Further, if the number of the grooves 9A and the connecting pipes 11 of the elastic body 9 is increased, the dust collecting effect of the chips of the workpiece W can be improved. That is, the dust collector 6 can radially suck the debris of the workpiece W generated at the construction point of the laser peening from each groove 9A of the elastic body 9 so that the debris does not interfere with the optical path of the laser beam L.

Fig. 4 is a front view showing another configuration example of the elastic body 9 shown in fig. 1 to 3.

Instead of the groove 9A, a through hole 9B may be formed in the elastic body 9. For example, as shown in fig. 4, a groove is formed in the annular elastic layer 9C having high elasticity, and the annular lubricating layer 9D having high lubricity is superimposed on the groove, whereby the elastic body 9 having the through hole 9B can be produced. The through hole 9B formed in the elastic body 9 can be connected to the connecting pipe 11. Of course, the through-holes 9B may be formed in the single-layer elastic body 9, without being limited to the example shown in fig. 4.

In order to prevent the debris of the workpiece W from staying in the vicinity of the laser peening point, it is preferable to provide not only the discharge port of the dust collection air for collecting the debris of the workpiece W but also the intake port of the dust collection air at an appropriate position. Specifically, it is preferable to form a laminar flow of the dust collecting air toward the connecting pipe 11 without crossing the working point in the nozzle 8.

Therefore, it is appropriate to form the air intake port 8A for taking the dust collecting air into the nozzle 8 on the side of the workpiece W with respect to the lens 7 of the nozzle 8. However, from the viewpoint of preventing accidents, it is preferable that the nozzle 8 be provided with an air intake port 8A having a structure in which scattered light of the laser light L does not leak to the outside of the nozzle 8.

Fig. 5 is an enlarged sectional view showing the structure of the air intake port 8A shown in fig. 1, and fig. 6 is a right side view of the air intake port 8A shown in fig. 4.

For example, as shown in fig. 5 and 6, the air intake port 8A can be configured such that the laser beam L and the outside of the nozzle 8 cannot be linearly connected through the air intake port 8A. Specifically, the air intake port 8A can be formed by a wall surface having a double structure disposed with a gap in a direction perpendicular to the optical axis of the laser light L. In addition to the examples shown in fig. 5 and 6, the air intake port 8A may be formed by 2 wall surfaces inclined with respect to the optical axis of the laser beam L.

The nozzle 8 may be formed in a cylindrical shape, and the center axis of the nozzle 8 may be offset from the optical axis of the laser beam L. That is, the nozzle 8 may be made eccentric. In this way, the swirl of the dust collecting air is formed in the nozzle 8, and the center of the swirl can be shifted from the working point of the laser peening. Thus, the dust collector 6 can suck the debris of the workpiece W from the grooves 9A and the through holes 9B formed in the elastic body 9, and the debris of the workpiece W is not accumulated at the laser peening point.

By performing the laser peening of the workpiece W using the laser peening apparatus 1 having the above-described configuration, a finished product or a semi-finished product can be manufactured.

(Effect)

The laser peening apparatus 1 and the laser peening method as described above do not require a medium such as a liquid or a coating by using an ultrashort pulse laser such as a femtosecond laser. Therefore, according to the laser peening apparatus 1 and the laser peening method, the size of the laser oscillator 2 can be drastically reduced as compared with the case of using a nanosecond laser. As a result, the laser peening apparatus 1 can be made portable.

The laser peening apparatus 1 and the laser peening method can shield the laser beam L and collect dust of debris of the workpiece W in order to avoid leakage of light with high intensity and retention of debris of the workpiece W, which are considered to be adverse effects caused by use of an ultra-short pulse laser beam or use of no liquid. In particular, by attaching the elastic body 9 to the tip of the nozzle 8, it is possible to prevent the laser light L, the scattered light, and the reflected light from leaking while avoiding damage to the workpiece W. Further, the dust of the workpiece W can be collected from the groove 9A or the through hole 9B formed in the elastic body 9. As a result, the laser peening of the workpiece W can be performed under good conditions while avoiding the laser light L from being blocked by the debris.

(other embodiments)

While the specific embodiments have been described above, the embodiments described above are merely examples and do not limit the scope of the invention. The novel methods and apparatus described herein may be embodied in various other forms. In the method and apparatus embodiments described herein, various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The appended claims and their equivalents are intended to include such various aspects and modifications as fall within the true scope and spirit of the invention.