JPS5930514B2 - Electron beam welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron beam welding device, and more particularly, to a device for welding a plurality of materials to be welded by overlapping or abutting them.

[Prior art]

Electron beam welding equipment is a device that performs welding by irradiating the material to be welded with an electron beam generated from an electron beam source and heating the material by the electron beam impact. Therefore, for example, when overlapping or butt welding two materials to be welded, it is better to make the welding depth as deep as possible to ensure strong welding.

However, when welding is performed by setting the welding depth deep enough for the electron beam to penetrate the welding surface, a protrusion called a back bead is formed by the melted welding material on the back side of the welding surface. This is not preferable because it requires cutting when overlapping other materials on the back side of the weld. In order to satisfy these conflicting demands, when setting the welding depth by adjusting the intensity of the electron beam generated from the electron beam source, the depth is determined by adjusting the thickness of the non-welded materials to be welded. I keep it to a moderate level. However, even when welding is performed with these settings, the weld depth may be affected due to differences in the characteristics inherent to the materials to be welded or the intensity of the electron beam generated from the electron beam source may vary greatly due to some reason. In some cases, the thickness became excessive, resulting in the formation of the protrusions. Therefore, in order to solve this drawback, an electron beam detector is placed directly below the electron beam irradiation point of the material to be welded, and it is monitored to see if a detection signal is generated from this electron beam detector. It has been considered to stop welding when a detection signal is generated, but this has not been realized due to the following problems. First, as shown in an enlarged view in FIG. 1, there are minute irregularities on the surface of the material to be welded.

Therefore, there is a slight variation in the thickness of the stacked materials to be welded, and there is also a small variation in the intensity of the electron beam generated from the electron beam source. Therefore, even when the actual welding depth is appropriate and almost no protrusions occur, the electron beam irradiation point is irradiated directly above a minute recess u on the surface of the material to be welded, as shown in Figure 1, for example. The electron beam passes through the welding material and enters the electron beam detector. However, if welding is stopped in such a case, welding cannot be performed efficiently. Secondly, the electron beam detector inevitably detects noise pulses, and it is expected that the noise pulses will cause the welding to stop. Therefore, in the past, when welding was performed with the welding depth set to about the overlap thickness, even if the welding depth became excessive for some reason, it was impossible to deal with it. [Object of the Invention] The present invention solves such conventional problems, and when welding materials to be welded are overlapped or butt welded by setting the welding depth to approximately the overlap thickness of the materials to be welded, the protrusion is It is an object of the present invention to provide an electron beam welding device that can prevent the occurrence of.

[Structure of the Invention] The present invention provides an apparatus for performing welding by irradiating an electron beam onto a material to be welded, which comprises: a detector for detecting an electron beam transmitted through the material by projecting the electron beam onto the material; a selection circuit for selecting only pulse signals of a certain level or higher from among the pulse-shaped output signals from the detector; a circuit for determining the integrated amount of the signals selected by the selection circuit within a predetermined time; It is characterized by comprising means for monitoring the output signal from the circuit and stopping or attenuating the irradiation of the electron beam onto the material when the amount of the signal exceeds a predetermined reference value. .

〔Example〕

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 2 is a drawing for showing one embodiment of the present invention, and in the figure, 1 is an electron beam generator, and the electron beam generator 1 is for applying negative high voltage to the electron gun 2 and the electron gun 2. High voltage power supply 3
and a heating power source 4 for supplying heating current to the electron gun 2. 5 is a mounting table for welding materials, and this mounting table 5
For example, two steel plates A and B to be welded are placed on the soil.

The mounting table 5 is movable in a direction perpendicular to the plane of the paper, and as the mounting table 5 moves, the electron beam EB generated by the electron gun 2 welds the steel plates A and B. Steel plate A,
In order to detect the electron beam EB transmitted through the beam B, an electron beam detector 6 such as a Faraday cup is provided. The output signal of the electron beam detector 6 is supplied to an amplifier 7, and the output signal of the amplifier 7 is supplied to a comparator 8.
Comparator 8 generates a square wave pulse when the signal supplied by amplifier 7 exceeds a predetermined level. The output pulses of comparator 8 are supplied to integrator 9. The integrator 9 repeats discharging at regular intervals. The output signal of the integrator 9 is supplied to a response circuit 10. A response circuit 10 monitors the output signal of the integrator 9 and generates a response signal when the level of this output signal exceeds a predetermined constant value. When the response signal is supplied to the heating power source 4, the heating power source 4 operates to stop supplying the heating current. Further, the output signal of the response circuit 10 can be supplied to an alarm circuit 11, and the alarm circuit 11 issues an alarm by supplying the response signal. In the above-described configuration, the intensity of the electron beam generated by the electron beam generator 1 is adjusted to set the welding depth to approximately the overlap thickness of the materials to be welded.

Next, the mounting table 5 for the materials to be welded is moved at a constant speed in a direction perpendicular to the plane of the paper, and the electron beam EB is generated from the electron gun 2 and irradiated onto the steel plates A and B, which are the materials to be welded. As a result, even when the welding depth is appropriate, each time the electron beam is irradiated directly above the recess U shown in Fig. 1, the electron beam EB passes through the material to be welded and the electron beam is intermittently incident on the detector. Therefore, the output signal of the detector 6 becomes as shown in period T1 in FIG. 3a. In FIG. 3a, p indicates a detection pulse generated when the electron beam is incident on the detector 6, and q indicates a noise pulse. The output signal from this detector 6 is amplified by an amplifier 7 and then supplied to a comparator 8. The comparator 8 generates a shaped pulse based on a preset reference level shown as E1 in FIG. 3a when a pulse above this reference level is supplied from the amplifier 7. Therefore, the comparator 8 generates a pulse as shown in FIG. 3b, which corresponds one-to-one to the detection pulse p. The output signal of the comparator 8 is supplied to an integrator 9, which integrates the output signal of the comparator 8 and repeats discharging at regular intervals. Therefore,
The output signal of the integrator 9 is as shown in FIG. 3c.
Now, if the welding depth starts to become excessively deep for some reason, the electron beam will pass through the material to be welded even if the stacked thickness of the material to be welded is very slightly thinner than the average, and as shown in Figure 3. As shown by period T2 in a, the frequency with which the electron beam passes through the material to be welded and enters the detector 6 increases. As a result, the output of the integrator 9 exceeds the response level of the response circuit 10 indicated by E2 in FIG. 3c, and as a result, a response signal as shown in FIG. 3d is outputted from the response circuit 10. Since this response signal is supplied to the heating power source 4, the heating power source 4 stops supplying the heating current, and the generation of the electron beam EB from the electron beam generator 1 is stopped. Therefore, welding can be performed with the welding depth as deep as possible while avoiding excessive welding to the extent that protrusions are produced on the back surfaces of the steel plates A and B, which are the materials to be welded. still,
When the welding depth becomes excessive, a response signal from the response circuit 10 is supplied to the alarm circuit 11.
1 issues an alarm and informs the operator of an abnormality. In the embodiment described above, the electron beam generator 1 is controlled based on the output signal of the response circuit 10, and the electron beam generator 1 is activated when an abnormality occurs.
However, a deflector for deflecting the electron beam from the electron beam generator 1 is provided, and the deflector is stopped based on the output signal of the response circuit 10. The welding depth of the material to be welded may be prevented from becoming excessive by operating the electron beam to move the irradiation point of the electron beam from the material to be welded onto a separately provided beam trap. .

Further, in the above embodiment, the generation of the electron beam from the electron beam generator 1 is stopped based on the output signal of the response circuit 10O, but it is also possible to limit the generation of the electron beam to attenuation instead of stopping.

Furthermore, in the embodiment described above, the output signal of the comparator 8 was configured to be guided to the integrator, but instead of the integrator, the output signal is guided to the counting circuit, and the counted value per predetermined time of the counting circuit is set as the counted value. The configuration may be such that the response circuit generates a response signal when the response exceeds .

〔effect〕

As is clear from the above description, according to the electron beam welding apparatus based on the present invention, when welding materials to be welded are overlapped or butt welded by setting the welding depth to approximately the overlap thickness of the materials to be welded, , it is possible to prevent the protrusion from occurring.

[Brief explanation of the drawing]

Figure 1 is intended to explain that when welding is performed with the welding depth set to approximately the same thickness as the overlapping thickness, the electron beam will intermittently pass through the material to be welded even if the welding depth is appropriate. FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram illustrating output signals from each circuit element of the embodiment shown in FIG. 2. 1: Electron beam generator, 2: Filament, 3: High voltage power supply, 4: Heating power supply, 5: Mounting table, 6: Electron beam detector, 7:
Amplifier, 8: Comparator, 9: Integrator, 10: Response circuit, 11: Alarm circuit.

Claims (1)

[Claims] 1. In a device that performs welding by irradiating an electron beam onto a material to be welded, a detector for detecting an electron beam transmitted through the material by projecting the electron beam onto the material to be welded;
a selection circuit for selecting only pulse signals of a certain level or higher from among the pulse-shaped output signals from the detector; a circuit for determining the integrated amount of the signals selected by the selection circuit within a predetermined time; An electron beam welding device comprising means for monitoring an output signal from a circuit and stopping or attenuating irradiation of the electron beam onto the material when the amount of the signal exceeds a predetermined reference value.