JPS589783A - Method of inspection for laser working - Google Patents

Abstract

PURPOSE:To obtain good quality of working by detecting the amplitude of sound of working generated at the time of laser beam irradiation and thereby judging the quality of condition of working of a material to be worked. CONSTITUTION:A laser beam 2 oscillated from a laser oscillator 1 is changed its direction by a total reflecting mirror and passed through a condenser 4 to weld a material to be worked 5. Sound of working generated under an optimum state is stored in a memory circuit 13, and this memory signal and amplitude of sound of working 6 converted into electric signals are compared in a comparator circuit 14. If the difference of amplitude is within a specified limit, a signal that indicates good welding condition is displayed on a display device 15, and if it is not acceptable, a signal indicating bad is shown on the device 15. Accordingly, when a signal of bad is displayed during working, laser output, the distance between the condenser 4 and the material 5, etc. are controlled to obtained good quality of working.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser machining inspection method for determining the quality of the machining state of a workpiece to be machined by laser machining, and for inspecting whether the machining amount is a predetermined value. be.

A conventional laser processing inspection method will be explained based on FIGS. 1 and 2.

In Figure 1, (1) is a laser oscillator, (2) is a laser beam with a pulsed waveform output from the laser oscillator (1), and (3) is a dichroic mirror disposed in the path of the laser beam (2). , (4) is the laser beam (2)
(6) is the workpiece, (6) is the condenser lens for condensing the light.
) is generated from the surface of the workpiece (5) before processing, (7)
is a microphone that detects (6) before processing, (8) is an electric circuit that amplifies the generation time before processing, shapes the waveform, etc.
(9) is a comparison circuit or a photoelectric element that converts the laser beam (2) into an electric signal.

Figures 2(a) to 2(d) each illustrate the principle of the conventional method.
This is a diagram showing the waveform (6) before processing when the laser output and pulse waveform are constant and the workpiece density at the laser beam (2) irradiation point on the workpiece (5) is changed. (left side) and the melted shape of the workpiece (5) (right side). The power density of the laser beam (2) on the workpiece (5) is highest in the state shown in Fig. 2(a), and in the state shown in Fig. 2(d).
The state of □ is the smallest.

Further, each continuous time taztl of the processing sound wave corresponds to one pulse of the laser beam irradiated to the workpiece.

Next, a case where welding is performed as an example of laser processing operation will be described. First, a laser beam (2) having a pulsed waveform is oscillated from a laser oscillator (1), and a part of the laser beam (2) is removed by a dichroic mirror (3) to change its direction and enter a condenser lens (4).

As a result, the workpiece (Is) is welded. At this time, the workpiece (6) absorbs the laser beam (2) at the irradiation point and is heated. Due to this heating, the workpiece (5) reaches a high temperature and is melted and welded, but some of it reaches the boiling point and evaporates. At this time, a machining amount (6) is generated from this machining point.

As shown in FIG. 2 (IL), when the power density of the laser beam (2) is high, the amount of processing (6) per pulse beam (-1a) is long, and The penetration depth ha also becomes deeper. To ←°, from Fig. 2 ~) to (d
), as the passé density of the laser beam (2) becomes lower, the generation time tb-ta of the processing amount (6) becomes shorter, and the corresponding penetration depth hb-ha also becomes shallower.

Based on the relationship between the welding state and the time during which the amount of processing per pulse beam occurs, a microphone (7) for detecting the amount of processing (6) is installed, and the amount of processing (6) is detected electrically by the electric circuit (8). The electricity of the oscillation time per pulse of the laser beam (2) is converted into a signal, inputted into the comparison circuit (9), transmitted through the Gikkreuzk mirror (3), and converted into an electric signal by the photoelectric element axis. The signal is also input to the comparison circuit (9) and compared with the time at which the machining amount occurs, and if it is within a predetermined time difference, it outputs an output signal indicating that it is appropriate, and if it is not, it outputs an output signal indicating that it is inappropriate. The quality of the welding was judged.

However, the conventional laser processing inspection method compares the oscillation time per pulse of a laser beam that oscillates in a pulsed manner and the amount of processing that occurs. Could not be applied. In other words, when welding a predetermined location with a continuously oscillating laser beam, the laser beam is continuously irradiated onto the workpiece with a constant output, so the corresponding amount of processing is also continuous for a constant period of time. Occur. For this reason, the conventional method of inspecting the amount of machining by detecting the start time of the amount of machining has the disadvantage that the quality of the machining can only be determined after welding at a predetermined location has been completed.

This invention was made in order to eliminate the drawbacks of the conventional methods as described above, and by detecting the amplitude of the amount of processing that occurs when irradiating a workpiece with a laser beam, it is possible to generate a continuously oscillating laser beam. An object of the present invention is to provide a laser machining inspection method that can determine whether the machining state is good or bad during beam machining.

A case in which welding is carried out by laser processing will be described below with reference to FIGS. 3 and 4.

In Fig. 3, aυ゛ is a total reflection mirror that changes the direction of the laser beam (2), a is an electric circuit that amplifies the amplitude and shapes the waveform, etc. (II is a memory circuit that stores the amplitude value of the machining amount that occurs when the optimal machining condition is obtained.

A4 is a comparison circuit, and a9 is a display device that displays the output of the comparison circuit I. The figures in the figure are the same as in Figure 1. The same reference numerals are given to the priest parts.

4(a) to 4(d) are diagrams for explaining the present invention in detail, and show the waveform of the processing amount (on the left) and the processed amount when the laser output is constant and the density is changed. This shows the melted shape of the workpiece (right side). The power density of the laser beam (2) on the workpiece is highest in the state shown in Figure 2 (a), and rd in Figure 2 (←) is the same as in Figure 2 (a), respectively.
, (b) , (0) , (indicates the amplitude value of the machining amount that occurs in the state of a).

Next, the laser processing operation m- will be explained regarding welding. First, the laser beam oscillated from the laser oscillator (2)
The direction is changed by the total reflection mirror 0, and the condensing lens (4)
This focuses the laser beam (2) and welds the workpiece (5). At this time, as shown in FIG. 4(a), the processing amount (6) generated from the processing point becomes larger when the power density of the laser beam is high.

Further, the penetration depth ha also increases. Furthermore, Fig. 4~)
From ((1), the power density of laser beam (2) becomes ′
Therefore, as the i-in depth becomes shallower, the value of the amount of machining that occurs also becomes smaller.

From this relationship between the welding state and the amplitude before processing, the third
The amplitude value before processing that occurs when the optimum state is obtained is stored in advance in the memory circuit member shown in the figure as an electrical signal. The memory signal of this memory circuit I and the microphone (
7) An output signal indicating that if there is no electricity is defective is sent to the display device a9 to judge whether the welding condition is good or bad during processing. Therefore, if an output signal indicating a defect occurs during processing, stable processing quality can be obtained by controlling the laser output, the distance between the condensing lens (4) and the workpiece (5), etc. become.

In the above embodiment, a microphone is provided for detection before processing, but other equipment may be used as long as it can detect the amplitude value before processing.

In addition, in the above embodiment, the case of welding was explained, but
It can also be applied to inspection of laser processing such as drilling, trimming, and scribing, and can also be applied when the waveform of the laser beam is pulsed.

As described above, according to the present invention, a continuous waveform laser beam is used by detecting the amplitude value before processing that occurs during laser beam irradiation.

In the case of machining, it is possible to know the machining status during machining, and also to detect machining defects caused by abnormalities in machining condition factors, such as a decrease in laser output or positional deviation of the workpiece. This has the effect of consistently obtaining high processing quality.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional side view for explaining the conventional inspection method.
FIG. 2 is a diagram showing the molten state before processing. FIG. 3 is a cross-sectional side view for explaining an inspection method according to an embodiment of the present invention, and FIG. 4 is a diagram showing the melted state before processing. (1) Laser oscillator (2) Laser beam (5) Workpiece (6) Before processing (7) Microphone In the figures, the same reference numerals indicate the same or equivalent parts. Applicant Makoto Saka, Director of the Agency of Industrial Science and Technology - Figure 2 (α) (b) (C) (d)

Claims (1)

[Claims] A workpiece is processed with a laser beam from a laser oscillator, and the pre-processing signal generated from the processing part of the workpiece is detected, and the M7F! A laser machining inspection method characterized by determining the quality of four machining states of a workpiece.