JPS6230513B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding device that preferably performs continuous welding mainly using a laser.

Many devices have been proposed that are equipped with a laser oscillator and perform welding using laser light from the laser oscillator. In this case, the commercial frequency of 50 or 60 Hz and its rectified pulsating current contained an alternating current component that produced continuous oscillation, or other types that repeated pulse oscillation were used. However, when continuous welding is performed using a device equipped with the above laser oscillator, the following problems occur. In other words, during irradiation with laser light, the molten material (so-called hot water) in the welding part of the workpiece is generally accompanied by gasified gas, but it is excited by the DC component of the constant current and radiated from the oscillator. Since the output of the laser beam is constant, the hot water in the welded area is not particularly stirred, but instead becomes hot water with a gaseous body coexisting with it, and solidifies continuously in that state, so there is a so-called nest of gaseous bodies inside the welded part. This results in a weak surface, and the surface becomes scaly, requiring grinding as a post-process to obtain a particularly smooth machined surface. Furthermore, laser light excited by a current containing a commercial alternating current component in its direct current component has a modulated excitation current compared to that produced by a direct current, so its output varies; or 60 Hz frequency is used as excitation current as it is, and at this low frequency, the hot water in the welding area cannot be sufficiently stirred and the gas contained in the hot water cannot be expelled, so only the above DC current is used. The disadvantages are almost the same as in the case of .

Furthermore, in addition to the above drawbacks when irradiating pulsed laser light, the welded part is intermittently heated, so during the solidification process, the solidification area becomes larger than in the above two methods, which causes a large amount of distortion during solidification. There was a problem that a solidified surface layer was formed. In other words, the surface of the welded part is wavy,
In pulse oscillation, the length of the above-mentioned wavy unit wave is longer than the above two, and the amount of distortion to be relaxed is reduced by the longer length, so the internal distortion becomes larger.
The drawback was that there was a high incidence of cracks appearing in the welded area after welding.

In order to solve the above-mentioned drawbacks, the present invention is designed to excite and output the current input to the excitation source by superimposing not only a constant current direct current component but also an alternating current with a frequency sufficiently higher than the commercial frequency. This welding device incorporates as one component a laser oscillator that emits laser light by forcibly modulating it, and it always forms a stable and highly reliable weld on the workpiece.

Hereinafter, the present invention will be explained based on the drawings showing one embodiment thereof.

First, regarding the laser oscillator, which is the main component of the present invention, the construction and operation of the excitation means for the excitation source inside the laser oscillator will be described. In FIG. 1, a first DC power supply 10 is provided, and this power supply is connected to an excitation light source 14, which is a component of a laser oscillation section, via diodes 11, 12 and a transformer 13 for preventing backflow. On the other hand, an alternating current signal generator 16 is provided, and the signal output from this generator is amplified to an arbitrary magnitude by a switching transistor 15 and is then input to the transformer 13. The switching transistor 15 is operated by a second DC power supply 18. Note that a diode 17 is connected between the collector of the switching transistor 15 and the second DC power supply 18.

In the above circuit, a frequency of, for example, 1 kHz is output from the AC signal generator 16 that varies the frequency (in this case, the frequency range is selected from 500 Hz to 5 kHz depending on the material and shape of the workpiece).
If this is generated, the current acting on the excitation light source 14 will be a constant current DC component Idc and a high frequency AC component Iac shown in FIG. A laser substance (not shown) made of gas or solid and equipped with a resonant circuit is excited by the excitation light source 14 that receives this current, and generates a constant output X shown in FIG. 2B and an oscillation output Y of a desired frequency and amplitude. Superimposed laser light is emitted. Therefore, a laser oscillator is equipped with an excitation power source consisting of the above circuit, which is an example, and a condensing system for condensing the laser light emitted from the laser oscillator and a workpiece to be welded to be irradiated with the above laser light are mounted. In addition, if a welding device is formed by a stage driven by a drive mechanism that is movable in three dimensions including position adjustment with the light focusing system, and a control device that controls the laser oscillator and drive mechanism, Figure 2B
The welding part of the welded object is constantly melted at a constant power X by the action of the laser beam having the output curve shown in Figure 2. Hot water containing gas is generated, but at the same time, this hot water has a vibration output Y.
The above-mentioned hot water is vibrated and stirred in a very short period of time to efficiently release the gas in the hot water to the outside of the hot water, and the above-mentioned vibration smoothes the surface of the hot water during the solidification process and significantly alleviates the distortion that occurs. Forms a good weld on the object to be welded.

As described in detail above, the present invention applies a forcedly modulated current containing a high frequency component to an excitation source, and provides a laser oscillator that emits the resulting laser beam output after forced modulation. Since the welding device is combined with a means for welding the workpiece by irradiating the object to be welded, the laser oscillator and the means work efficiently, and compared to conventional laser welding devices, there is no void and distortion is significantly reduced. The present invention has achieved the effect of constantly and stably forming a smooth welded part, thereby achieving the provision of a welded product that is highly reliable in terms of strength and does not require any post-processing.

Note that the circuits shown in the above embodiments are merely examples, and the present invention is not limited thereto.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of an excitation power supply circuit for sending to the excitation light source of the present invention, Figure 2A is a current curve diagram generated by the above circuit, and Figure B is an output curve diagram of laser light emitted from a laser oscillator. It is. 10, 18... DC power supply, 11, 12, 17... Diode, 13... Transformer, 14... Excitation light source, 1
5... Switching transistor, 16... AC signal generator.

Claims (1)

[Claims] 1. In a laser welding device comprising a laser oscillation unit, an excitation power supply connected to the laser oscillation unit, and a device for irradiating a workpiece with laser light emitted from the laser oscillation unit, the excitation power supply outputs a constant current. a first DC power source; an AC signal generator that generates an AC signal of 500 Hz to 5 kHz; an element that converts the signal output from the AC signal generator into an amplified signal of arbitrary magnitude; a second DC power supply for operation, and a first DC power supply for transmitting the amplified signal.
and means for coupling to a DC power source.