JP2001071164A - Method for monitoring of part to be worked and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable monitoring of formation of an oxidized film of a surface to be worked in process. SOLUTION: In the case of executing laser beam welding after laser cutting, a reference light emitting intensity of a welded part under irradiation with laser beam while no oxidized film is formed on the laser beam cutting surface and an actual light emitting intensity of the welded part detected by an optical sensor 10 are compared by a comparing means 11; and in the case that the actual light emitting intensity is judged by a means for recognizing oxidation 13 to be stronger than the reference light emitting intensity, formation of oxidized film on the welded surface is recognized, and formation of oxidized film on the surface to be worked is monitored in process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring method and apparatus for recognizing the degree of surface cleanliness of a workpiece based on the light emission state of the workpiece and, more particularly, to laser welding after laser cutting. At this time, the formation of an oxide film on the welding surface is recognized based on the degree of light emission of the laser weld.

[0002]

2. Description of the Related Art Laser light is highly directional and has high energy, so it is precisely welded, cut, drilled, and surface modified by condensing it into small points or lines to form a laser beam. It is used for processing. For example, in repair welding of construction members and the like, a process of performing laser cutting using laser light and performing laser welding as it is performed.

In laser cutting, a workpiece is melted by a laser beam and cut by an oxidative exothermic reaction. At the time of laser cutting, since oxygen gas or nitrogen gas is supplied for cutting, it is necessary to prevent an oxide film from being formed on the cut surface. Further, it is necessary to prevent oxidation from proceeding during laser welding even if an oxide film is formed to some extent.

If an oxide film is formed on the cut surface or oxidation progresses during laser welding, a predetermined strength may not be obtained in the welded portion after laser welding, and the degree of cleaning of the groove surface may be reduced by welding. It has a big impact on quality.
In the process of performing laser cutting and laser welding as it is, the presence or absence of the formation of an oxide film was indirectly determined by inspecting the welded material. Then, the flow rate of the cutting gas, the angle of the cutting nozzle, and the control of the shielding gas in laser welding are controlled so that the predetermined strength is maintained, that is, in order to suppress the formation of the oxide film.

[0005]

In the process of performing laser cutting and performing laser welding as it is, the processing is performed continuously, but the presence or absence of formation of an oxide film is indirectly determined by inspecting the welded material. Therefore, there is a possibility that laser welding may be performed in a state where the oxide film is formed. Therefore, there is a possibility that a welded material that does not achieve a predetermined welding quality may be processed, and the yield is deteriorated.

For this reason, if the presence or absence of the formation of an oxide film can be detected during processing, it is possible to immediately take measures to suppress the formation of an oxide film, thereby stabilizing welding quality and improving the yield. . However, at present, a technology for detecting whether or not an oxide film is formed during processing has not been established.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a method for monitoring a workpiece to be processed by irradiating a laser beam with the degree of surface cleanness of the workpiece to be processed during the processing, and a method thereof. It is intended to provide a device.

[0008]

According to the present invention, there is provided a method for monitoring a workpiece to be processed. The method includes the steps of: Is recognized. Further, in order to achieve the above object, the monitoring method of the processed part of the present invention is a method of irradiating the laser beam when the laser beam is irradiated with the reference emission intensity at the time of proper cleaning degree of the processed part when irradiating the laser beam. It is characterized by comparing the actual light emission intensity of the processed part with the actual light emission intensity, and when the actual light emission intensity is higher than the reference light emission intensity, the deterioration of the cleanness of the processed surface is recognized. Further, in order to achieve the above object, the method of monitoring a processed part according to the present invention comprises the steps of: obtaining a reference light emission intensity of the processed part when irradiating a laser beam when an oxide film is not formed on the processed surface; And comparing the actual light emission intensity of the processing target portion when irradiating with the laser light, and recognizing the formation of an oxide film on the processing surface when the actual light emission intensity is higher than the reference light emission intensity. . The work surface is a welding surface.

In order to achieve the above object, a method of monitoring a workpiece according to the present invention is characterized in that, when performing laser welding after performing laser cutting, a laser beam is emitted when an oxide film is not formed on the laser cut surface. A comparison is made between the reference light emission intensity of the welded portion when irradiated and the actual light emission intensity of the welded portion when irradiated with the laser beam. The formation of an oxide film is recognized.

Then, after the formation of the oxide film on the welding surface is recognized, the formation of the oxide film on the welding surface is suppressed by controlling the flow rate of the cutting gas for laser cutting. After the formation of the oxide film on the welding surface is recognized, the formation of the oxide film on the welding surface is suppressed by controlling the angle of the laser nozzle for laser cutting. Further, after the formation of the oxide film on the welding surface is recognized, the formation of the oxide film on the welding surface is controlled by controlling the cutting gas flow rate of the laser cutting and the angle of the laser nozzle. Further, after the formation of the oxide film on the welding surface is recognized, the amount of shielding gas for laser welding is increased to suppress oxidation during welding. Further, the invention is characterized in that the amount of shielding gas in laser welding is increased to suppress oxidation during welding. Further, the reference light emission intensity and the actual light emission intensity detect light intensity of a wavelength in an ultraviolet region.

[0011] In order to achieve the above object, the configuration of the apparatus for monitoring a workpiece according to the present invention is a monitoring apparatus for a workpiece which monitors the workpiece when performing laser welding after performing laser cutting. A sensor that detects information on the actual emission intensity of the laser weld, and the reference emission intensity of the laser weld when the laser beam is irradiated when an oxide film is not formed on the laser cut surface is stored and from the sensor. The information of the actual light emission intensity is input, the comparison means for comparing the reference light emission intensity and the actual light emission intensity, and the comparison information from the comparison means is input, and the input information is compared with the reference light emission intensity. And an oxidation recognizing means for recognizing the formation of an oxide film on the welding surface when the information having the actual emission intensity is high.

And a control means for inputting recognition information of the formation of the oxide film from the oxidation recognition means, wherein the control means has a function of stopping the laser cutting and the laser welding, and a cutting of the laser cutting. A function of controlling the gas flow rate to suppress the formation of an oxide film on the welding surface; a function of controlling the angle of a laser nozzle for the laser cutting to suppress the formation of an oxide film on the welding surface; It has a function of increasing the amount of shielding gas for welding to suppress oxidation during welding. Further, the control means further has a function of selectively performing each of the functions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have studied in the past that when oxidation occurs due to deterioration of a shield or the like during welding,
We found that the luminous intensity from the weld and the plume increased, and by focusing on this point, a method and apparatus for monitoring the workpiece, specifically, the state of oxide film formation on the weld surface when performing laser welding And a device for recognizing the same have been invented.

Referring to the drawings, a description will be given of a monitoring apparatus for implementing a method of monitoring a workpiece according to an embodiment of the present invention. The illustrated device includes a laser cutting device and a laser welding device, and recognizes the state of formation of an oxide film on a workpiece (welded surface) based on the emission intensity of the welding surface when performing laser welding after performing laser cutting. Things. Then, depending on the state of oxide film formation on the welding surface, stop laser welding, control the cutting gas flow rate for laser cutting, control the angle of the laser nozzle for laser cutting, and increase the shielding gas amount for laser welding Or let them do that.

FIG. 1 shows an entire configuration of a monitoring apparatus for implementing a method for monitoring a workpiece according to an embodiment of the present invention, and FIG. 2 shows a control flowchart of the monitoring apparatus. 3 to 5 show a laser 1.
The state of change in light emission intensity per pulse is shown.

As shown in FIG. 1, a laser cutting device 1 and a laser welding device 2 are provided. The laser cutting device 1 cuts the workpiece 4 by the laser beam L1 from the laser nozzle 3, and can control the angle of the laser nozzle 3 and the flow rate of the cutting gas. The laser welding device 2 can continuously weld the workpiece 4 cut by the laser cutting device 1 as it is with the laser beam L2 from the welding head 5, and can control the state of the shielding gas.

The laser welding device 2 transmits, for example, a laser beam from a YAG laser oscillator 6 through an optical fiber 7 and collects the laser beam incident from the optical fiber 7 through a reflection optical system 8 and a condenser lens optical system 9. The workpiece 4 is irradiated with the emitted laser beam L2 to contribute to laser welding. In the laser welding device 2, the light emission state of the laser welded portion (emission wavelength, emission intensity, etc .: information of actual emission intensity F)
The optical sensor 10 for detecting the
Detects an in-process light emission state coaxial with the laser beam L2. Information on the actual light emission intensity F detected by the optical sensor 10 is input to the comparison means 11. Reference numeral 12 in the drawing denotes an optical fiber holder.

The light emitting state (information on the reference light emission intensity f) when the laser beam is irradiated when the oxide film is not formed on the welding surface, that is, when the welding surface has an appropriate degree of cleanness, is stored in the comparing means 11. It is stored in advance. The comparing means 11 compares the information on the actual light emission intensity F detected by the optical sensor 10 with the information on the reference light emission intensity f, and inputs the comparison information to the oxidation recognition means 13.

The oxidation recognizing means 13 stores in advance the state of light emission when a laser beam is irradiated when an oxide film is formed on the welding surface. That is, as shown in FIG. 3 to FIG. 5, the change state of the light emission intensity per laser pulse according to the laser wavelength is stored in advance. FIG. 3 shows the change in the light emission intensity per laser pulse with a laser wavelength of, for example, 400 nm (ultraviolet region). FIG. 4 shows the change in the light emission intensity per laser pulse with a laser wavelength of, for example, 600 nm. Indicates the change of the emission intensity per laser pulse with a laser wavelength of, for example, 940 nm. The solid line indicates the reference emission intensity f, and the dotted line indicates the case where an oxide film is formed on the welding surface having a value higher than the reference emission intensity. Is the emission intensity.

That is, when the actual light emission intensity F input to the oxidation recognizing means 13 approaches the light emission intensity indicated by the dotted line at each wavelength (when the actual light emission intensity F is higher than the reference light emission intensity f), the welding is performed. It is recognized that an oxide film is formed on the surface.
The degree of formation of the oxide film is recognized based on the degree of approach. The laser wavelength is, for example, 400nm (ultraviolet region)
Thus, the difference in light emission intensity between the case where the oxide film is not formed on the welded surface and the case where the oxide film is formed is remarkable. This is because the sensitivity in the high temperature region is high in the ultraviolet region, and high-precision monitoring can be performed by detecting the emission intensity of the laser wavelength in the ultraviolet region.

Recognition information of the formation of the oxide film from the oxidation recognizing means 13 is input to the control means 14.
The control means 14 has a function of stopping laser cutting by the laser cutting device 1 and a laser welding by the laser welding device 2, a function of controlling a cutting gas flow rate of the laser cutting to suppress the formation of an oxide film on a welding surface. It has the function of controlling the angle of the laser nozzle for laser cutting to suppress the formation of an oxide film on the welding surface, and the function of suppressing the oxidation during welding by increasing the amount of shielding gas for laser welding. . Further, the control means 14 is provided with a function for selectively executing the above functions. Then, a predetermined operation command is output from the control means 14 by each function according to the state of formation of the oxide film.

The operation of the above-described monitoring device will be described with reference to FIG. The loaded workpiece 4 is laser-cut by the laser cutting device 1, laser-welded by the laser welding device 2 as it is, and carried out. During the welding by the laser welding apparatus 2, the optical sensor 10 detects the light emission state of the laser welded portion (light emission detection), and the wavelength range is extracted by transmission through the spectral filter. Step S
In step 1, the reference light emission intensity f is compared with the actual light emission intensity F (comparing means 11). If it is determined that the actual light emission intensity F is higher than the reference light emission intensity f, for example, oxidation recognition is performed based on the situation in FIG. The means 13 recognizes that an oxide film is formed on the welding surface (step S2). At this time, the degree of formation of the oxide film is also recognized at the same time. In addition, FIG. 4, FIG.
It is also possible to recognize the formation of the oxide film based on the situation of FIG.

In step S2, the actual light emission intensity F of the welding surface
Is higher than the reference light emission intensity f, it is determined how close the actual light emission intensity F is to the light emission intensity when the oxide film shown by the dotted line in FIG. 3 is formed. It recognizes the formation and the degree of formation.
That is, when the actual light emission intensity F is higher than the reference light emission intensity f, the deterioration of the degree of cleanness of the surface to be processed is recognized.

When the formation of the oxide film is recognized in step S2, the processing is stopped, the flow rate of the cutting gas, the nozzle angle is controlled, the shielding gas is controlled, and the welding quality is maintained by the functions of the control device 14. To do. That is, when the formation of the oxide film is progressing to a state where the welding strength cannot be obtained, the laser cutting device 1 and the laser welding device 2 are stopped, and the processing is stopped. In addition, when the welding strength can be obtained in the current state of forming an oxide film, but the welding strength cannot be obtained if the formation of the oxide film proceeds further, the cutting gas flow rate of the laser cutting device 1 is increased, or the nozzle angle is increased. Control to suppress the formation of an oxide film during laser cutting. Also,
The shield gas of the laser welding device 2 is controlled to suppress the formation of an oxide film during laser welding.

Therefore, in the process of performing laser cutting and laser welding as it is, it is possible to monitor the formation of an oxide film on the weld surface in-process. For this reason, when an oxide film is formed, it is possible to take measures to stop the processing or immediately suppress the formation of the oxide film, and there is no possibility that laser welding is performed in a state where the oxide film is formed. A welded material for which welding quality cannot be obtained is not processed, so that welding quality can be stabilized and yield can be improved.

In the above-described embodiment, in the processing of performing laser cutting and laser welding as it is, the formation of an oxide film on the welding surface after laser cutting is recognized. In the processing to be performed, it is also possible to apply to recognition of the formation of an oxide film on the welding surface. Further, the processing after the recognition of the formation of the oxide film is not limited to the above embodiment, and another processing may be performed.
Further, although the formation of an oxide film has been described as an example of the surface cleanliness, the surface cleanliness can be applied to other conditions as long as the degree of light emission of the processed portion changes. However, the monitoring is not limited to monitoring.

[0027]

According to the method for monitoring a processed portion of the present invention, the degree of surface cleanness of a processed surface is recognized based on the light emission state of the processed portion when a laser beam is irradiated. It becomes possible to monitor the degree of surface cleanliness of the work surface.

In the method of monitoring a processed part according to the present invention, the reference light emission intensity when the processed part is properly cleaned when irradiating the laser beam and the processing intensity of the processed part when the laser beam is irradiated are determined. The actual emission intensity is compared with the actual emission intensity, and when the actual emission intensity is higher than the reference emission intensity, the deterioration of the degree of cleanliness of the surface to be processed is recognized. It becomes possible to monitor.

Further, the method of monitoring a portion to be processed according to the present invention is characterized in that the reference light emission intensity of the portion to be processed when the laser beam is irradiated when an oxide film is not formed on the surface to be processed and the laser beam irradiation The actual light emission intensity of the processed part is compared with the reference light emission intensity, and when the actual light emission intensity is higher than the reference light emission intensity, the formation of an oxide film on the surface to be processed is recognized. It becomes possible to monitor the formation of an oxide film on the processed surface.

Further, in the method of monitoring a portion to be processed according to the present invention for achieving the above object, when performing laser welding after performing laser cutting, a laser beam is irradiated when an oxide film is not formed on the laser cut surface. A comparison is made between the reference light emission intensity of the welded portion when irradiated and the actual light emission intensity of the welded portion when irradiated with the laser beam. By monitoring the formation of the oxide film on the surface to be processed in-process, there is no risk of laser welding with the oxide film formed. Yield can be improved by stabilizing.

After the formation of the oxide film on the welding surface is recognized, the cutting gas flow rate of the laser cutting is controlled to suppress the formation of the oxide film on the welding surface.
Also, after recognizing the formation of an oxide film on the welding surface, since the angle of the laser nozzle for laser cutting is controlled to suppress the formation of the oxide film on the welding surface,
After recognizing the formation of the oxide film on the welding surface, the cutting gas flow rate of the laser cutting and the angle of the laser nozzle were controlled to suppress the formation of the oxide film on the welding surface. After recognizing the formation of an oxide film on the surface, the amount of shielding gas for laser welding was increased to suppress oxidation during welding.In addition, the amount of shielding gas for laser welding was increased to increase oxidation during welding. Therefore, when an oxide film is formed, a measure for immediately suppressing the formation of the oxide film can be taken.

Further, since the reference light emission intensity and the actual light emission intensity detect light intensity having a wavelength in an ultraviolet region, detection can be performed in a region having high sensitivity, and recognition of formation of an oxide film can be accurately performed. it can.

The structure of the monitoring device for a workpiece according to the present invention is a monitoring device for a workpiece which monitors a workpiece when performing laser welding after laser cutting. A sensor for detecting information of the intensity, and the reference emission intensity of the laser welded portion when the laser beam is irradiated when the oxide film is not formed on the laser cut surface is stored and the information of the actual emission intensity from the sensor is stored. A comparison unit for comparing the reference emission intensity with the actual emission intensity, and comparison information from the comparison unit being input, and the input information is higher in the actual emission intensity than the reference emission intensity. Oxidation recognizing means for recognizing the formation of an oxide film on the welding surface when information is provided. By recognizing the formation of oxide film on the weld surface when the actual emission intensity to the emission intensity is high, it is possible to monitor the formation of the oxide film of the surface to be processed in process. As a result, there is no possibility that laser welding is performed in a state where the oxide film is formed, and the welding quality can be stabilized and the yield can be improved.

Further, there is provided control means for inputting recognition information of the formation of an oxide film from the oxidation recognition means, wherein the control means has a function of stopping the laser cutting and the laser welding, and a function of cutting the laser cutting. A function of controlling the gas flow rate to suppress the formation of an oxide film on the welding surface; a function of controlling the angle of a laser nozzle for the laser cutting to suppress the formation of an oxide film on the welding surface; Since it has the function of suppressing the oxidation during welding by increasing the amount of shielding gas for welding, when an oxide film is formed, it is possible to immediately take measures to suppress the formation of the oxide film. Further, since the control means further has a function of selectively performing each of the functions, when an oxide film is formed, a measure for immediately suppressing the formation of the oxide film can be appropriately performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a monitoring device that implements a method of monitoring a workpiece according to an embodiment of the present invention.

FIG. 2 is a control flowchart of the monitoring device.

FIG. 3 is a graph showing a change in light emission intensity per laser pulse;

FIG. 4 is a graph showing a change in light emission intensity per laser pulse.

FIG. 5 is a graph showing a change in light emission intensity per laser pulse.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser cutting apparatus 2 Laser welding apparatus 3 Laser nozzle 4 Workpiece 5 Welding head 6 YAG laser oscillator 7 Optical fiber 8 Reflection optical system 9 Condensing lens system 10 Optical sensor 11 Comparison means 12 Optical fiber holder 13 Oxidation recognition means 14 Control means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Akabane 1-1-1 Wadasaki-cho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Kazuhiro Urata Marunouchi, Chiyoda-ku, Tokyo 5-1-1-1 Sanyo Heavy Industries Co., Ltd. (72) Inventor Yoshiaki Shimogusuku 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo F-term in Kobe Shipyard, Mitsubishi Heavy Industries, Ltd. 2G043 AA03 BA01 CA05 DA08 DA09 EA10 FA07 GA02 GA04 GB03 HA01 HA02 HA05 KA03 KA05 KA09 LA01 MA01 MA11 4E068 AA05 AE00 BA00 CA17 CB01 CB04 CC01 CH06

Claims (14)

[Claims] 1. A method for monitoring a processed part, comprising: recognizing a degree of surface cleanness of a processed surface based on a light emission state of the processed part when irradiating a laser beam. 2. The method of claim 2, wherein the reference light emission intensity when the laser beam is irradiated is compared with the reference light emission intensity when the processing portion is properly cleaned and the actual light emission intensity when the laser beam is irradiated. A method of monitoring a processed part, wherein the degree of cleanliness of a processed surface is recognized to be deteriorated when the actual emission intensity is higher than the intensity. 3. A reference light emission intensity of a portion to be processed when a laser beam is irradiated when an oxide film is not formed on a surface to be processed and an actual light emission intensity of the portion to be processed when the laser beam is irradiated. A method for monitoring a processed part, comprising: when the actual light emission intensity is higher than the reference light emission intensity, recognizing formation of an oxide film on a surface to be processed. 4. The method for monitoring a workpiece according to claim 1, wherein the workpiece is a welded surface. 5. When performing laser welding after performing laser cutting, the reference light emission intensity of a welded portion when a laser beam is irradiated when an oxide film is not formed on a laser cut surface, and when the laser beam is irradiated. Comparing the actual light emission intensity of the welded portion with the reference light emission intensity and recognizing the formation of an oxide film on the welding surface when the actual light emission intensity is higher than the reference light emission intensity. Method. 6. The method according to claim 5, wherein after the formation of the oxide film on the welding surface is recognized, the formation of the oxide film on the welding surface is controlled by controlling a cutting gas flow rate of laser cutting. Monitoring method of the processed part. 7. The method according to claim 5, wherein after the formation of an oxide film on the welding surface is recognized, the angle of a laser nozzle for laser cutting is controlled to suppress the formation of an oxide film on the welding surface. The monitoring method of the processed part. 8. The method according to claim 5, wherein after the formation of the oxide film on the welding surface is recognized, the cutting gas flow rate of the laser cutting and the angle of the laser nozzle are controlled to suppress the formation of the oxide film on the welding surface. A method of monitoring a workpiece to be processed. 9. The processing part according to claim 5, wherein, after recognizing the formation of an oxide film on the welding surface, the amount of shielding gas for laser welding is increased to suppress oxidation during welding. Monitoring method. 10. The method for monitoring a workpiece according to claim 6, wherein the amount of shielding gas for laser welding is increased to suppress oxidation during welding. 11. The device according to claim 1, wherein the reference light emission intensity and the actual light emission intensity are:
A method for monitoring a processed part, comprising detecting light intensity having a wavelength in an ultraviolet region. 12. A monitoring device for a workpiece to monitor a workpiece when performing laser welding after laser cutting, comprising: a sensor for detecting information on an actual emission intensity of the laser weld; The reference emission intensity of the laser welded portion when the laser beam is irradiated when the surface is not formed with an oxide film is stored, and information of the actual emission intensity from the sensor is input, and the reference emission intensity and the actual emission intensity are input. Comparison means for comparing the intensity with the comparison information from the comparison means, and the input information is an oxide film on the welding surface when the actual emission intensity is higher than the reference emission intensity. A monitoring device for a processed part, comprising: an oxidation recognition means for recognizing the formation of slag. 13. The apparatus according to claim 12, further comprising control means for inputting recognition information of formation of an oxide film from the oxidation recognition means, wherein the control means has a function of stopping the laser cutting and the laser welding. A function of controlling the cutting gas flow rate of the laser cutting to suppress the formation of an oxide film on the welding surface, and controlling an angle of a laser nozzle of the laser cutting to suppress the formation of an oxide film on the welding surface. And a function of increasing a shielding gas amount of the laser welding to suppress oxidation during welding. 14. The apparatus according to claim 13, wherein the control unit further has a function of selectively executing each of the functions.