JP2001179470A - Laser beam machining state measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining state measuring apparatus suitable for detecting a defect of a machined part in-line in an actual manufacturing line and capable of realizing joint use for an observation optical system in a compact constitution. SOLUTION: A sensor head 20, in which a welding beam is received from a welding place while having coaxial with an optical axis of the laser beam irradiating a work 16 and plural optical systems, which extracts plural specific wave length beams from a received welding beam, outputs in the horizontal direction and is accommodated in a case, is arranged above a casing of a laser beam torch 13, a welding state is detected by transducing plural extracted specific wave length beams to electrical signals and using the signals. A concave lens 21 for converging is arranged movably between the laser beam torch and the sensor head, an observation optical system by CCD camera 40 being coaxial with an optical axis of the laser beam is arranged above the sensor head.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing state measuring apparatus for a laser processing machine which performs processing by irradiating a laser beam to a work with a laser torch, and particularly to a laser processing state suitable for detecting a defect in laser welding. It relates to a measuring device.

[0002]

2. Description of the Related Art In laser welding, a pulsed or continuous laser beam output from a laser oscillator is applied to a target work through a laser torch to perform welding. In particular, YAG laser welding is often applied to precision mass production lines, and high productivity and quality are regarded as important.

Heretofore, defect inspections in laser welding have often been carried out off-line visually or using inspection equipment. In this case, the burden on the inspector is large in a mass production line that requires inspection of a large number of locations. In addition, it is important that the inspection time is short from the viewpoint of the productivity of the mass production line, and it is desirable to perform the defect inspection in parallel with the welding. This is because it is important to perform an in-line inspection of all products and, if a welding defect occurs, immediately remove the defective product and pursue the cause.

[0004]

In response to such a demand, there has been provided a defect measuring apparatus capable of automatically measuring a defect by measuring light from a welded portion (for example, Japanese Patent Application Laid-Open No. H11-157,086). No. 10-217470).

In this defect measuring apparatus, a means for extracting and receiving light from a processed portion of a work for each wavelength is provided in a housing of a laser torch. The light from the plurality of light receiving means is guided to another location via an optical fiber, and is converted into an electric signal by a sensor by a photoelectric converter arranged at another location, and then the signal is processed. As described above, it is effective to separate and measure light from a processed portion into a plurality of wavelength bands in order to obtain a large amount of welding state information. However, when considering application of such a defect measurement device to an actual production line, it is not practical to arrange the sensors so as to approach from a different location independently of the laser torch. This is because the arrangement of sensors that approach the laser torch independently from another direction often has no space between the laser torch and the work. Therefore, it is practical to use an optical system that is optically coaxial with the laser torch.

The above defect measuring apparatus also has a problem that an observation optical system cannot be used together.
The observation optical system generally uses a CCD camera, and is important for observing a processed part at the time of teaching or the like.

[0007] In view of the above, the object of the present invention is to provide:
It is an object of the present invention to provide a laser processing state measuring apparatus suitable for performing in-line defect detection of a processing part in an actual production line and realizing a combined use of an observation optical system with a compact configuration.

[0008]

According to the present invention, there is provided a laser processing machine for processing a workpiece by irradiating a laser beam with a laser torch having a built-in condensing optical system through the condensing optical system. Above the housing, a plurality of light sources for receiving light from the processing portion in such a manner as to be coaxial with the optical axis of the laser light applied to the work, extracting light having a plurality of specific wavelengths from the received light, and outputting the extracted light. A sensor head formed by housing the optical system in a case is provided, and an observation optical system using visible light is installed on the upper part of the case so as to be coaxial with the optical axis, and the processing portion is formed by the observation optical system. A concave lens for condensing light from the processing part on the sensor head side is arranged between the sensor head and the condensing optical system so as to be observable and movably along the optical axis. And the plurality Laser machining state measuring device, characterized in that the detection of machining state by using light of a plurality of specific wavelength extracted by Manabu system is provided.

In the laser processing state measuring device, the observation optical system is realized by a CCD camera, and a convex lens for condensing light on the CCD camera side is provided between the CCD camera and the sensor head. , Are arranged movably along the optical axis.

In the laser processing state measuring device, when the light from the processing portion includes the reflected light of the laser light from the processing portion and the plasma light generated in the process of processing, the plurality of optical A first reflection mirror that reflects a reflected light component of the laser light in a direction perpendicular to the optical axis and transmits the remaining component in the optical axis direction;
A second reflecting mirror that reflects the component of the plasma light from the light transmitted through the reflecting mirror in a direction perpendicular to the optical axis, and the case in which the plurality of reflecting mirrors are overlapped in the optical axis direction. It is characterized by being housed in

In the laser processing state measuring device, each of the plurality of optical systems further includes a first optical filter for extracting a reflected light component of the laser light reflected by the first reflecting mirror; A second optical filter that extracts a component of the plasma light reflected by the second reflection mirror.

In the laser processing state measuring apparatus, when the plurality of optical systems are optical systems that do not transmit visible light, the plurality of optical systems are detachably provided on the case.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where an embodiment of the present invention is applied to a laser welding machine will be described with reference to FIG.
In FIG. 1, continuous or pulsed laser light (for example, wavelength 1.06
(4 nm) is guided to the laser torch 13 by the transmission fiber 12 and irradiated on the work 16 through the YAG laser reflecting mirror 14 and the optical lens (condensing optical system) 15 arranged in the housing of the laser torch 13 to perform welding.

A sensor head 20 is provided above a housing of the laser torch 13. A work 16 is provided between the case of the sensor head 20 and the housing of the laser torch 13.
A concave lens 21 for condensing light (hereinafter, referred to as welding light) emitted from a welding portion so as to be coaxial with the optical axis of the laser light (hereinafter, referred to as irradiated laser light) applied to the laser beam. I have. The concave lens 21 transmits the welding light to the sensor head 2.
It has a function of condensing light on the optical system within 0, and can be moved in the optical axis direction of the irradiation laser light, that is, in the vertical direction (Z-axis direction) by a mechanism described later. The welding light includes plasma light generated during the welding process, reflected light of irradiation laser light, and ambient light. YAG laser reflection mirror 14
In, the laser beam from the transmission fiber 12 is of course
Most of the reflected laser light from the welded spot is reflected, but only a small portion is transmitted, and plasma light and visible light are almost transmitted.

Above the concave lens 21, only the reflected light (wavelength: 1.064 nm) component of the irradiation laser light of the welding light is reflected in the horizontal direction (X-axis direction), and the remaining light is reflected in the optical axis direction (Z-axis direction). Direction) is provided. On the transmitting portion side of the YAG light reflecting mirror 22, that is, on the upper side, of the transmitted light of the YAG light reflecting mirror 22,
A reflection mirror 23 is provided to reflect a specific wavelength component defining the plasma light in the horizontal direction. That is, the YAG light reflecting mirror 22 and the reflecting mirror 23 are superimposed in the optical axis direction in the case of the sensor head 20, and furthermore, are positioned at 45 degrees with respect to the optical axis.
They are arranged at an angle of degrees. The YAG light reflecting mirror 22 and the reflecting mirror 23 are also different depending on whether visible light is transmitted or not for the reason described later.
No. 0 is detachably provided. That is, when visible light is not transmitted, it is made detachable. Normally, the YAG light reflecting mirror 22 transmits visible light,
Does not transmit visible light. Therefore, in this case,
At least the reflection mirror 23 is detachable from the case of the sensor head 20.

In the direction of reflection of the YAG light reflecting mirror 22, that is, in the horizontal direction, a condensing lens 24 for condensing the reflected light from the YAG light reflecting mirror 22, and an irradiation laser light from the condensed reflected light. A YAG optical bandpass filter 25 for extracting only the reflected light component is provided.

Similarly, in the horizontal direction of the reflection mirror 23,
A condensing lens 26 for condensing the light reflected from the reflecting mirror 23 and a plasma light bandpass filter 27 for extracting only the plasma light component from the condensed reflected light are provided.

With the above configuration, the welding light emitted from the welding portion of the work 16 is condensed by the concave lens 21 installed coaxially with the irradiation laser light, and the YAG light reflecting mirror 22 condenses the welding light.
Only the AG light is reflected in the horizontal direction, and subsequently, the plasma light is reflected in the horizontal direction by the subsequent reflection mirror 23, thereby separating the welding light into the reflected light of the irradiation laser light and the plasma light.
After the separation, the YAG light is cut through a YAG light band-pass filter 25 in a wavelength range other than the YAG light. The plasma light passes through the plasma light band transmission filter 27 to cut off light in a wavelength range other than the plasma light.

Light emitted from the YAG optical bandpass filter 25 is converted into a voltage signal corresponding to the received light intensity by a photodiode sensor 31 including one or more photodiodes as a photoelectric conversion element and an amplifier, and the welding state is determined. Output to the processing device 33. On the other hand, the light exiting the plasma light band transmission filter 27 is converted into a voltage signal corresponding to the received light intensity by a photodiode sensor 32 including one or more photodiodes and an amplifier, and output to a welding state determination processing device 33. You. In the case where the amount of light received by the photodiode sensors 31 and 32 is large, a neutral density filter having an appropriate transmittance may be arranged before them.

The welding state determination processing device 33 performs determination processing such as defect detection for each work based on the voltage signals from the photodiode sensors 31 and 32, and displays the result as necessary on the display device 34 or the storage device 35. To display and memorize. The processing algorithm for detecting a defect is disclosed in, for example, “Laser Welding Defect Detection Apparatus (Japanese Patent Application No. 9-213223)” already filed by the present applicant.

Briefly, a processing algorithm for detecting a defect includes a low-pass filter for converting a voltage signal into a digital voltage signal and removing a predetermined high-frequency component from the digital voltage signal, and a low-pass filter for the low-pass filter. A differential processing unit for differentiating the output to output a differential signal; and detecting a first defect based on whether a value of the digital voltage signal exceeds a first threshold value L1, and detecting a first defect of the digital voltage signal. The value is the first threshold L1
A first processing means for detecting a second defect based on whether the value is lower than a second threshold value L2, which is lower than the second threshold value L2. The third threshold value L3 and the fourth threshold value L4 (where L
3> L4) Second detection for detecting whether or not the range is exceeded
Processing means, the detection result of the second processing means and the first processing means
And a defect type discriminating processing unit for detecting, when there is an output from only the second processing means in response to the detection result of the processing means, as a third defect.

With such a configuration, the defect detection can be performed by executing the processing algorithm for the defect detection on the two voltage signals from the photodiode sensors 31 and 32. The processing algorithm for defect detection is described in, for example, Japanese Patent Application No. 10-233721.
And the photodiode sensor 3
A processing algorithm in the case where there are a plurality of photodiodes in Nos. 1 and 32 is disclosed in the aforementioned Japanese Patent Application No. 10-217470.

As is clear from the above description, the present embodiment
Welding light emitted from the welding point is detected by a sensor head 20 placed coaxially with the optical axis of the laser light through an optical lens 15 and a concave lens 21 in a laser torch 13, and further, the welding light is separated into a plurality of wavelength bands. This is a device that performs defect measurement at another location after converting it into an electrical signal.

Further, in this embodiment, a CCD camera can be used together. That is, the CCD camera 40 is installed above the case of the sensor head 20. Such a mechanism for installation can be realized by using a well-known technique, and thus a detailed description is omitted. As mentioned earlier, C
Considering the observation of the welded area by the CD camera 40, YA
The G light reflecting mirror 22 and the reflecting mirror 23 are detachable from the case of the sensor head 20 when visible light is not transmitted. Also, the case of the sensor head 20 and the CC
A convex lens 41 is provided between the camera and the D camera 40. The convex lens 41 is for condensing light on the CCD camera 40, and for focusing on the CCD sensor,
It is movable in the optical axis direction, that is, in the vertical direction by a mechanism described later. When using the CCD camera 40,
Of the mirrors in the sensor head 20, those that do not transmit visible light are removed from the case. By installing such a CCD camera 40, it is possible to easily observe a welding location using the CCD camera 40 at the time of initial adjustment such as setting welding conditions. In particular, since the sensor head 20 is fixed, measurement reproducibility is good before and after each mirror is attached and detached.

The housing of the laser torch 13 has YA
A power monitor 39 is provided at a position corresponding to the G laser reflection mirror 14. The power monitor 39 is arranged so as to receive only a part of the laser light transmitted through the YAG laser reflection mirror 14. For example, when a continuous laser beam is used, the power monitor 39 measures the laser beam energy per unit time, monitors whether there is any abnormality in the irradiated energy, and outputs the monitoring result to the welding state determination device 33.

With reference to FIG. 2, an adjusting mechanism 50 for making the concave lens 21 movable will be described. Adjusting mechanism 50
Is a cylindrical case 51 disposed between the housing of the laser torch 13 and the case of the sensor head 20;
1 includes a lens holder 52 that can slide along the inner surface of the case 51 while holding the lens holder 1, and a screw-type knob 53 for moving the lens holder 52 up and down and fixing the lens holder 52 at a desired position. When the screw knob 53 is loosened, the lens holder 52 can be moved up and down,
When tightened, the lens holder 52 is fixed at that position.

With reference to FIG. 3, an adjusting mechanism 60 for making the convex lens 41 movable will be described. Adjusting mechanism 60
Has the same configuration as the adjustment mechanism 50 described above, and has a cylindrical case 61 disposed between the case of the sensor head 20 and the CCD camera 40 and a case 6 holding the convex lens 41.
A lens holder 62 slidable along the inner surface of the lens holder 1;
The lens holder 62 is moved up and down and the lens holder 6 is moved up and down.
And a screw-type knob 63 for fixing 2 in a desired position. When the screw-type knob 63 is loosened, the lens holder 62 can be moved up and down, and when tightened, the lens holder 62 is fixed at that position.

FIG. 4 shows the overall appearance of the irradiation system including the laser torch 13, the sensor head 20, and the CCD camera 40.
It is the figure shown from the opposite side to FIG.

In the above description, a YAG laser oscillator is used as the laser oscillator.
For example, the present invention can be applied to a laser welding machine using a CO ₂ laser oscillator or an excimer laser oscillator. In this case, the configuration of the optical system and the selection of the photodiode are performed so that the reflected light of the irradiation laser light can be detected. Also, the application field of this device is not limited to laser welding machines, but also includes drilling, cutting,
Alternatively, the present invention can be applied to a laser processing machine that performs a surface treatment.

[0030]

According to the present invention, the following effects can be obtained.

1. Since the measuring means has a compact configuration installed coaxially with the laser torch, it can be easily applied to an actual production line.

2. By measuring the reflected light of the irradiation laser light and the plasma light, the processing state can be determined from various angles, which contributes to the improvement of the accuracy of defect detection.

3. Since the measuring means is fixed coaxially with the laser torch, the reproducibility of the measurement is good.

4. A CCD camera is installed above the sensor head, and can be used together with the CCD camera at the time of initial adjustment such as setting welding conditions.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration when the present invention is applied to a laser welding state measuring device.

FIG. 2 is a cross-sectional view illustrating a vertical adjustment mechanism of the concave lens illustrated in FIG. 1;

FIG. 3 is a cross-sectional view illustrating a vertical adjustment mechanism of the convex lens illustrated in FIG. 1;

FIG. 4 is a diagram showing the external appearance of the entire irradiation system including the laser torch, the sensor head, and the CCD camera shown in FIG. 1 as viewed from the side opposite to FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Transmission fiber 13 Laser torch 14 YAG laser reflection mirror 15 Optical lens 16 Work 20 Sensor head 21 Concave lens 22 YAG light reflection mirror 23 Reflection mirror 24, 26 Condensing lens 25 YAG light band transmission filter 27 Plasma light band transmission filter 31, 32 Photo Diode sensor 40 CCD camera 41 Convex lens 52, 62 Lens holder 53, 63 Screw type knob

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hidetoshi Tsukihara 63-30 Yuyugaoka, Hiratsuka-shi, Kanagawa F-term (reference) 2F065 AA49 CC15 DD02 DD06 FF42 FF44 GG04 GG09 GG09 in Hiratsuka Works GG22 HH13 JJ01 JJ03 JJ05 JJ09 JJ18 JJ26 LL02 LL04 LL20 LL22 LL24 NN02 NN16 PP02 QQ03 QQ25 QQ33 2G043 AA03 BA01 CA02 CA05 EA10 FA06 GA04 GB01 GB19 HA01 HA02 HA09 JA03 KA05 CB09 CD03 CD04

Claims (5)

[Claims] 1. A laser beam machine for irradiating a work by irradiating a laser beam to a work through a condensing optical system with a laser torch having a built-in condensing optical system, wherein the work is radiated above a housing of the laser torch. A plurality of optical systems for receiving light from a processing portion so as to be coaxial with the optical axis of the laser light to be extracted, extracting a plurality of specific wavelengths of light from the received light, and outputting the extracted light are housed in a case. A sensor head is provided, and an observation optical system for visible light is installed on the upper part of the case so as to be coaxial with the optical axis so that the processed part can be observed by the observation optical system. Between the condensing optical system, a concave lens for condensing light from the processing portion toward the sensor head is disposed so as to be movable along the optical axis, and is extracted by the plurality of optical systems. Multiple features Laser machining state measuring device, characterized in that the detection of machining state by using light of a wavelength. 2. A laser processing state measuring apparatus according to claim 1, wherein said observation optical system is a CCD camera.
The CCD is provided between the CD camera and the sensor head.
A laser processing state measuring device, wherein a convex lens for condensing light on a camera side is arranged movably along the optical axis. 3. The laser processing state measuring device according to claim 1, wherein the light from the processing part includes a reflected light of the laser light from the processing part and a plasma light generated in a processing process. A first reflection mirror for reflecting the reflected light component of the laser light in a direction perpendicular to the optical axis and transmitting the remaining component in the optical axis direction, as the plurality of optical systems; A second component for reflecting a component of the plasma light in a direction perpendicular to the optical axis from light transmitted through
A plurality of reflecting mirrors are accommodated in the case so as to overlap in the optical axis direction. 4. The laser processing state measuring apparatus according to claim 3, wherein each of the plurality of optical systems further extracts a reflected light component of the laser light reflected by the first reflecting mirror. A laser processing state measuring device comprising: an optical filter; and a second optical filter that extracts a component of the plasma light reflected by the second reflection mirror. 5. The laser processing apparatus according to claim 1, wherein when the plurality of optical systems are optical systems that do not transmit visible light, the plurality of optical systems are detachably provided on the case. Condition measuring device.