JPS6016877B2 - Laser welding management method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to laser welding, and more particularly to a method for indirectly determining the quality of laser-welded parts to perform quality control.

When welding workpieces using a laser, appropriate welding conditions are determined by the pulse width of the emitted laser beam, the diameter of the beam when focused by a lens, and the energy to be input.

In this case, if the pulse width and focused diameter are kept constant, appropriate welding conditions can be obtained by changing the energy. In other words, the quality of laser welding can be controlled by controlling the energy. Specifically, by setting an appropriate energy range in advance, the actually applied energy is monitored, and this value is compared with the preset energy to determine the quality of welding. By the way, YAG lasers, glass lasers, etc. use xenon or krypton lamps for laser oscillation, but when observing the oscillation waveforms of these lamps (referred to as lamp a and lamp b here) with a YAG laser, As shown in FIG. 1, it can be seen that for the same energy, lamp a has a higher peak value. Also,
When a molybdenum plate is irradiated with laser at the same energy using these lamps a and b, a difference occurs in the penetration depth, and as shown in FIG. 2, lamp a shows a larger value than lamp b. In FIGS. 1 and 2, the curve shown by a solid line is the characteristic of lamp a, and the curve shown by a broken line is the characteristic of lamp b. As can be seen from this, it is difficult to control the penetration depth only by managing the energy as described above, and it is necessary to consider the peak value of the waveform as well as the energy management. This invention was made in view of the above points, and detects a part of the laser light used for welding, converts it into an electrical signal, and obtains an output indicating the energy value and peak value from this electrical signal. , provides a laser welding management method that can perform accurate quality control by comparing each of these outputs with preset energy values and peak values, and zeroing them out so that the quality of the laser welding can be determined based on the comparison results. The purpose is to

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, 11 is a laser oscillator, 12 is a laser beam emitted from this laser oscillator 11, 13 is a dichroic mirror, 14 is a condenser lens, 15 is a workpiece,
16 is a processing table on which the workpiece 15 is placed and held; 17 is a laser detector; 18 is an energy value comparator; and 19 is a laser waveform peak value comparator. Most of the laser beam 12 emitted from the laser oscillator 11 is reflected by the dichroic mirror 13 and then passed through the condensing lens 14 to the workpiece 1.
Light is built on 5.

Further, the laser beam 12 other than that reflected by the dichroic mirror 13 passes through the dichroic mirror 13, travels straight as shown by the broken line in the figure, and enters the laser detector 17. This laser detector 17 converts the incident laser beam into a tortoise signal using an optical tortoise conversion element (not shown), and then converts this electrical signal to an energy value by using an integrating circuit or the like, and uses a peak value detection circuit. The energy value is converted into a peak value and output. The energy value is input to one input terminal of the energy value comparator 18, and the peak value is input to one input terminal of the peak value comparator 19. The above energy value comparator 1
An energy value in a predetermined range set in advance is input to the other input terminal of the peak value comparator 19, and a peak value in a predetermined range set in advance is input to the other input terminal of the peak value comparator 19. ing. With such a configuration, a part of the laser beam 12 currently being welded is detected by the laser detector 17, its energy value and peak value are obtained, and the energy value comparator 18 and the peak value comparator 19 The energy value in a predetermined range and the peak value in a predetermined range set in advance are compared with the detected energy value and peak value at that time, respectively, and welding can be managed based on the ratio results.

That is, if the energy value output from the laser detector 17 is within the set energy value range, it is determined that the energy value of the laser beam 12 currently performing welding is appropriate, and the laser detection If the peak value output from the device 17 is within the set peak value range, it can be seen that the peak value of the laser beam 12 currently performing welding is appropriate. Therefore, when both the energy value and the peak value are within the set range, it can be said that the laser beam 12 has an appropriate energy value and peak value when performing welding. By detecting the energy and peak value of the laser beam in this manner, accurate quality control of laser welding can be performed.
In this way, in the present invention, quality control in laser welding is performed by detecting energy and peak values, so there is a difference in processing characteristics due to the lamp encounter as shown in Figures 1 and 2. It also allows for accurate quality control. As explained above, according to the present invention, a part of the laser beam used for welding is detected and converted into an electric signal, and an output indicating the energy value and peak value of the laser beam is obtained from this electric signal. These outputs are compared with preset energy values and peak values, and the quality of the laser welding is judged based on the results. This allows for extremely accurate welding management and improved welding processing. It is possible to provide an extremely useful laser welding management method that achieves high quality.

Simple Explanation of the Drawings Figure 1 is a diagram showing laser oscillation waveforms using two types of lamps for general laser oscillation, Figure 2 is a diagram showing processing characteristics using the above two types of lamps, and Figure 3 is a diagram showing the processing characteristics of the two types of lamps. FIG. 1 is a configuration diagram showing an embodiment of the present invention.

11... Laser oscillator, 12... Laser light, 13...
Dichroic mirror, 14...Tsukuko lens, 15.
...Workpiece material, 17...Laser detector, 18...Energy value wind ratio shark, 19...Peak value dish ratio shark.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 Detecting a part of the laser beam used for welding and converting it into an electric signal, obtaining the energy value and peak value of the laser beam from this electric signal, and converting the energy value and a preset energy value. A laser welding management method characterized in that the peak value is compared with a predetermined peak value, and the quality of the laser welding is determined based on the comparison results.