JPS58125388A - Monitoring method of working state by laser - Google Patents

Abstract

PURPOSE:To decide abnormal working conditions and abnormal results, by comparing the time required for generation of light emission from a working part after irradiation of a laser, or the maximum value of a detecting signal in this time, with a value of a normal time. CONSTITUTION:Laser light 2 outputted from a laser oscillator 1 is reflected by a reflector 10, is condensed by a condensing lens 3, and is irradiated to an object to be worked, through protecting glass 4. In this case, a working sound generated at the time of working is detected by a microphone 11 installed at a specified distance from a working point, and a detected working sound waveform is observed by an oscilloscope 12.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a method for almost instantaneously detecting and monitoring abnormal conditions during laser processing.

Technical Foreground of the Invention In laser processing, as with cutting and grinding N11EI, it is necessary to detect whether the processing is being performed in a steady state, that is, to detect abnormal layers during processing. Nor. Conventionally, in laser processing, a part of the laser beam (2) emitted from the laser oscillator +1) is transmitted through a dichroic lens (4) before passing through the condensing lens (4), as shown in Clause 11fi. The abnormal state during processing was detected by taking it out from the mirror (5) and making it incident on the energy monitor (6), and determining the amount by which the energy number ζ phased out based on the integral value of the waveform.

[Background Art Zhao Point] - In the above case, the dichroic and cummirror (5) are heated by a focused laser beam with high energy density (
2') is not placed on the optical path. Therefore, in the method of detecting the energy of the laser beam before it passes through the condensing lens (3) as described above, the trowel glass (4) is damaged by flying objects from the workpiece (7) during processing. However, the transmission of the laser (2') may be blocked and the incident energy to the workpiece (7) may decrease, or the power density of the laser spot on the processing surface may change due to variations in the thickness of the workpiece (7). There was a problem in which the phenomenon could not be detected even if the machining was not performed normally.

(Objective of the invention 3) To provide a method that can reliably know an abnormal state by detecting information obtained from processing phenomena during actual processing.

[Summary of the invention] Abnormal bite is detected by comparing the time from laser irradiation until light emission occurs from the processed part or the maximum value of the detection signal during this time with the normal value. It is.

[Embodiment j of the invention The inventors have conducted various experiments and found that in laser processing, the laser beam is irradiated as a beam that changes in response to changes in processing conditions such as energy and defocus distance. It was found that there is a time until the front is detected and a maximum value of the detected processed sound signal. The experimental method and experimental results conducted by the inventors will be explained.

The experimental method is shown in Figure 2.
The laser beam output from
The light is focused by a condensing lens (S) and irradiated onto the workpiece through a trowel glass (blind).At this time, the pre-processing that occurs during processing is detected by a microphone Qυ installed at a certain distance from the processing point. The processed sound waveforms were analyzed using an oscilloscope.

The amount of change in the experiment was power +! on the surface of the machined part. We chose energy and defocus distance of 0 to change the processing result by changing the Ij degree.

Figure 3 (→ to (d)) shows the surface of the oscilloscope α2 when the defocus distance (g) is changed. The previous waveform is shown, first (bl is the defocus distance of 0),
au+, (d) is the wave/form at 5jIJI. From these waveform diagrams, it was found that the 71tl sound waveform (-~(d)) was detected later than the laser oscillation waveform.It was also found that the time delay t differed depending on the defocus distance. In addition, the maximum value P of the sword Loe sound waveform
It was also found that Pl, Pl, and P3 differ depending on the defocus distance. Under the conditions of a condensing lens with a focal length of 50 m, a processing point of 0.761-thick SUS% as a proboscis, a distance of a microphone aυ of 11115 M, and an energy of 6 J, the luminescence obtained by taking the defocus distance ■ as the amount of change is FIG. 4 shows the time delay t and maximum value P determined from the waveform.

From this figure, it can be seen that the time delay t increases as the defocus distance is increased and the power density of the irradiated laser beam directed to the surface of the processed portion is decreased. Based on the relationship between the defocus distance and the time delay t, it is possible to detect a change in processing conditions, that is, a change in power density, due to a change in the defocus distance. When focusing on the maximum value P in FIG. 4, the maximum value P! It can be seen that G1 decreases as the power density decreases as the defocus distance increases a+, except in the case where the defocus distance is Qsw+, where the power density is high and the machined part becomes perforated.

Although this requires limitation of the applicable range, the maximum value P
Similarly to the time delay t, this means that it is an effective detection amount as a means for monitoring changes in machining conditions due to changes in the pointless removal distance.

Experimental results when energy is used as the amount of change are shown in Section 5-. In this figure, the condenser lens has a focal length of 90M, and the defocus distance q is O■.

Increasing the energy means increasing the power density of the irradiated laser beam on the surface of the processed part. It can be seen from FIG. 5 that when the energy is changed, the time delay t becomes larger and the strictness 11i P becomes smaller as the power density decreases, as in the case when the defocus distance peak is changed.

From the results in Figures 4 and 5, it is clear that when the power density of the irradiated laser beam on the workpiece surface decreases due to a decrease in energy or an increase in the defocus distance, It became clear that the time delay from 1 to the detection of the fore-sound increases, and the maximum value P of the processed sound waveform decreases. This means that time delay tl or adult 1i! i
This means that by measuring LP during each machining process and comparing it with the normal value, changes in power density due to changes in machining conditions can be detected.

Being able to detect changes in puff-[E due to changes in machining conditions means that it is possible to detect not only abnormalities in machining conditions but also power
! I'm hoping that it will be able to detect 7111 effects that are controlled by the E degree.

[Effects of the Invention] Before processing, there are waves generated as a result of evaporation during processing.

Using pre-processing as a signal source for monitoring means monitoring the progress of processing, which could not be detected using conventional energy methods2.

The method of the present invention that monitors before processing can detect changes in processing conditions due to a decrease in irradiation energy to the processed part due to damage to the lens, protective glass, etc. or changes in defocus distance. It is possible to determine abnormalities in conditions as well as abnormalities in results associated with abnormalities in processing conditions.

In addition, since values for monitoring can be measured at the same time as processing,
It is possible to determine the presence or absence of abnormalities in the machining conditions and machining results for each machining process, which is very useful! Be proactive.

[Brief explanation of the drawing]

IS1 diagram is an explanatory diagram of the conventional laser machining status rapid monitoring method.
Figure m2 is a diagram for explaining an example of this invention.
3 #A (Jl) is a laser oscillation waveform diagram, Fuki 3 diagram (婉〜(ψ) is the a-shaped diagram before processing, and Figure 4 is the before processing obtained by changing the defocus distance of the condenser lens. A measurement diagram showing the relationship between time delay t and maximum value P obtained from the waveform, and Figure 5 is a diagram showing experimental performance when energy is used as the amount of change. (1) Laser oscillator (3) ...Condensing lens αυ...Microphone αa...Oscilloscope 1st drawing!3 figure 14 figure, eyes, sushi 1 giant 1@, (Araso) power 2 friends (small) 1st Dero

Claims (1)

[Claims] Laser light emission - A method of detecting the sounding time from the start of laser light emission to the workpiece being irradiated by the laser beam until it occurs before processing, and the method of detecting the detected maximum value before processing, and how to measure the above sounding time or maximum value during normal processing. A method for monitoring a laser machining state, comprising: a method of detecting a machining state by comparing the value of .