JPS5915517Y2 - Laser oscillation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser oscillation device whose output peak value changes over time and which can provide laser light suitable for, for example, metal welding.

Conventionally, when welding metal using laser light, the surface is sufficiently heated and the inside is completely melted.
The peak value of laser output is varied.

Generally, this is achieved by superimposing a pulsating current on a laser excited by direct current to increase the laser output value.

FIG. 1 is a schematic configuration diagram showing an example of a conventional device of this type.
1 is a laser material such as a YAG rod, 2 is an excitation lamp, 3
and 4 are resonator mirrors disposed opposite to each other on both end surfaces of the laser material 1.

Further, reference numeral 5 (indicated by a broken line in the figure) is a condensing reflector provided surrounding the laser material 1 and the excitation lamp 2.

The excitation lamp 2 is driven by a DC power source 6, but the current is forcibly varied via a modulator 7.

Therefore, the laser substance 1 changes its laser oscillation output in accordance with the output of the excitation lamp 2 which is driven by the pulsating flow fluctuation.

This laser oscillation output is transmitted to the workpiece 9 via a condenser lens 8.
For example, laser welding is performed here.

Now, in such a device, the fluctuation frequency of the laser output by the modulator 7 is generally synchronized with the commercial power supply frequency due to its configuration, and is set to the power supply frequency or an integral multiple thereof.

However, when increasing the amount of penetration into the workpiece 9 during laser welding, it is better to set the frequency when increasing and decreasing the peak output of the laser beam to be lower than the above-mentioned power supply frequency.

However, when this is done with the above device, the input to the excitation lamp 2 increases rapidly when obtaining a large output peak value, which may lead to damage to the excitation lamp 2 due to thermal fluctuations in the excitation lamp 2.

Due to these circumstances, it is technically extremely difficult to vary the laser output at a low frequency in conjunction with various other conditions.

The present invention was developed in view of these circumstances, and its purpose is to create a laser oscillation system that has a simple configuration and whose peak output can be periodically varied at a low frequency that is suitable for various welding conditions. The goal is to realize and provide the device.

That is, the object is to realize a laser oscillation device with a simple structure that can modulate the peak output at a low repetition frequency.

Hereinafter, one embodiment of the device of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram of the same embodiment, and the same parts as in FIG.

This device has a laser material 1 sandwiched within a condensing reflector 5 and a 2
Two excitation lamps 2 a and 2 b are provided in parallel.

These excitation lamps 2a and 2b are driven by direct current from the power source 6, and are modulated and controlled through separate modulators 7a and 7b, respectively.

The modulation frequency of each modulator 7a, 7b is variable;
Alternatively, the period that is repeated in a pulsed manner is determined by the modulation control device 1.
It is set by 0.

This modulation control device 10 sets and controls both of the above to different periods.

In the device configured in this way, the excitation lamp 2a,
2b is shown by solid lines A and B in Fig. 3, respectively, at different frequencies f.
Pulsating flow is driven by a and fb.

As a result, the excitation lamps 2 a and 2 b individually excite the laser substance 1 with varying periods based on the frequencies fa and fb.

Therefore, the laser substance 1 is simultaneously excited by the excitation lamps 2a and 2b, and eventually outputs a laser beam corresponding to the combined value.

The peak value fluctuation characteristic of this output laser light is, for example, as shown by the broken line C in FIG.

Focusing on this characteristic C, its envelope, that is, the output change of the peak value has a frequency characteristic of fa-fb.

In other words, even though the excitation lamps 2a and 2b are individually driven at sufficiently high frequencies fa and ft, the output fluctuations (modulation frequency) of the device are sufficiently low (within the commercial power supply frequency). (compared to).

According to this action, the excitation lamps 2a, 2b
Since the lights are driven at high wave numbers fa and fb, there is no thermal fluctuation and the lights are averaged.

Therefore, the excitation lamps 2 a and 2 b are not damaged due to thermal stress.

In addition, since the laser output has a gentle peak value fluctuation, sufficient melt penetration is performed throughout the inside of the workpiece 9 when the laser output is high, and then when the peak output is low, The surface temperature can be sufficiently heated.

Therefore, the molten metal that has been melted to the inside is sufficiently stirred and fused, resulting in extremely good laser welding.

Conversely, if the object to be welded 10 is, for example, a metal with a high surface reflectance, energy loss can be reduced by sufficiently heating the surface with a laser output with a low peak value and then irradiating it with a laser output with a high peak value. The internal melting can be carried out without causing any damage.

Therefore, similarly good laser welding can be performed.

Further, as described above, this device can be realized with a very simple configuration and can be easily manufactured at low cost.

Now, the above explanation has been made regarding the case where the excitation lamps 2a and 2b are lit and driven by a pulsating current that changes in a sinusoidal manner.

However, as shown in FIG. 4 or FIG. 5, the same effect can be expected even when driving with pulse-like pulsating currents having mutually different periods.

In FIG. 4, a indicates the drive output of the excitation lamp 2a, and b indicates the drive output of the excitation lamp 2b.

Here, the driving periods T 1 and T 2 are set at a ratio of 2:3, so the combined output is as shown in FIG. 4C.

As is clear from the output characteristics shown in C, the average peak value at each time is the drive period T1. It can be changed at a repetition period T longer than T2.

Even in this case, since the excitation lamps 2a and 2b are each driven in a pulsed manner at a sufficiently high predetermined period, there will be no damage due to thermal averaging.

In addition, FIG. 5 shows the drive pulse P1 of the excitation lamp 2b shown in FIG.
As shown in the figure, the timing of generation of 2 is shifted every other time.

In this case, it is possible to obtain a combined laser output as shown in FIG.

Note that the present invention is not limited to the above embodiments.

For example, three or more laser excitation means may be provided, and the output may be controlled individually.

Alternatively, the laser substances 1 may be provided to correspond to the excitation lamps 2, respectively, and their respective outputs may be combined using a reflecting mirror, a lens, or the like.

Further, according to this device, not only seam welding but also spot welding can be performed.

In this case, the spot welding portion may be synchronized stepwise with each period of change in the peak value of the laser output.

It goes without saying that the driving frequency of the excitation lamp 2 may be determined depending on the specifications of the device and the material and shape of the workpiece to be welded.

Furthermore, although the above embodiments have been shown using a solid laser such as a YAG rod, a gas laser such as a CO2 laser or a semiconductor laser may also be used.

Alternatively, these different types of lasers may be driven separately and combined.

In short, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a conventional device, FIG. 2 is a schematic configuration diagram showing an embodiment of the device of the present invention, and FIG. 3 is a signal (laser output) waveform diagram showing the operation of the same embodiment. Figures 4 and 5 show signals (laser output) showing other embodiments, respectively.
FIG. 1... Laser substance, 2, 2 a, 2 b...
...excitation lamp, 3.4 ... resonator mirror, 5 ... condensing reflector, 6 ... DC power supply, 7, 7 a, 7 b. ...Modulator, 10...
...Modulation control device.

Claims (2)

[Scope of utility model registration request] (1) A plurality of laser excitation means each driving the laser in a variable or pulse manner at different periods to excite the laser, and a laser output whose peak value fluctuates at a period longer than the driving period due to the excitation by these excitation means. 1. A laser oscillation device comprising a laser emitting means for emitting laser light. (2) The plurality of laser excitation means includes a plurality of excitation lamps arranged in parallel in one laser active medium, a DC power supply commonly connected to one end of these excitation lamps, and the other end of this DC power supply. and the other ends of the plurality of excitation lamps, and five means for controlling the modulation of these modulators in a fluctuating or pulse-like manner at mutually different periods. A laser oscillation device according to claim 1 of the utility model registration claim.