JPS6255958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam welding method for butt welding parts to be welded by irradiating an electron beam to the butt part of the parts to be welded. Regarding welding methods.

Electron beam welding has the major characteristics of extremely deep penetration and narrow bead width compared to other welding methods, and is therefore increasingly being used for large structures made of thick plates.

However, when butt welding of thick plates is performed using the electron beam welding method, the tip of the weld is deflected toward one of the welded parts, making it impossible to obtain the desired joint length. Defects arise.

That is, as shown in FIG. 1, even if the electron beam 1 is accurately incident on the groove line 4 of the welded members 2 and 3, the electron beam 1 may be directed toward one of the welded members due to the influence of the magnetic field or electric field. As a result, most of the welded portion 5 deviates from the groove line 4, resulting in an unwelded portion of length l, making it impossible to obtain the desired joint length Y.

Conventionally, as a method for preventing such defects in the unwelded area, a groove line detection device such as a backscattered electron detection device or an optical detection device is provided, and an electron beam is accurately incident on the groove line. The welding equipment was equipped with a groove line tracing device to prevent the electron beam from deviating from the groove line during welding. However, all of these devices are based on the groove surface of the welding part, so even if there is an unwelded part inside the welded part, the defect cannot be detected until the welded part is completely cooled after welding and is subjected to a non-destructive inspection. Detection was impossible. On the other hand, the applicant has applied for a method of correcting the deflection of the tip of the weld using an ultrasonic flaw detection detector in Japanese Patent Application No. 54-29897, but in this method, the tip of the weld does not set the detector. There is a drawback when the beam is deflected to the side of the workpiece that is not in contact with the weld. Furthermore, the applicant applied in Japanese Patent Application No. 55-57856 for a method of controlling the irradiation position of the electron beam so that the tip of the weld is always deflected below a reference value toward the workpiece to be welded where an ultrasonic detector is set. However, this method has a limitation in that the abutting surfaces must always be irradiated with the electron beam at an angle within a certain range.

The object of the present invention was made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide an electron beam welding method that can stably secure a desired joining length.

In order to achieve such an objective, the present invention
A method of welding by irradiating an electron beam along the first groove line and monitoring the relationship between the welded part and the first groove line generated in the welded material using ultrasonic signals. A second groove line is provided near the tip of the weld at a predetermined distance from the first groove line so that reflected signals from the weld or the weld tip immediately after melting and solidification can be received at all times. It is characterized by this. Particularly preferably, in the above, the electron beam irradiation position is such that the distance between the second groove line and the tip of the welded part is always equal to the distance between the first groove line and the second groove line. Alternatively, one of the angles is controlled.

Furthermore, when an ultrasonic signal is emitted from the side surface of the workpiece to the butt weld, the echo level from the molten part or especially from the tip of the weld immediately after melting and solidification is relatively lower than the echo level of the second groove line. Focusing on the fact that a low reflected signal of Either the irradiation position or the angle is adjusted.

The present invention will be explained in detail below. Figures 2a to 4b show the second groove line provided near the tip of the weld, the deflection state of the tip of the weld, and the ultrasonic oscillation-receiving device (transducer) installed on the side of the workpiece. ) shows the relationship with the reflected signal from

As shown in Fig. 2a, Fig. 3a, and Fig. 4a, in addition to the first groove line 4 for ensuring the desired joint length, there is a groove line 4 near the tip of the weld. By providing the second groove line 6 at a position parallel to the groove line 4 and separated by a predetermined distance, the tip of the welded portion 5 (hereinafter referred to as the welded portion tip 5a) becomes the first groove line.
Even if the weld is deflected from the groove line 4 to the left or right, the reflected signal from the weld tip 5a can always be received.

Now, Fig. 2a shows a case where the welding part tip 5a coincides with the first groove line 4 and there is no deflection of the welding part tip 5a, and the ultrasonic reflection signal in this case is as shown in Fig. 2b. , a reflected signal 6' from the second groove line 6 and a reflected signal 5' from the welding portion tip 5a. In this case, by calculating the time difference Δt of each reflected signal, the distance difference Δx between the second groove line 6 and the welding portion tip 5a can be easily determined. Here, if the distance difference Δx determined from the time difference Δt during welding is equal to the preset distance difference Δl between the first groove line 4 and the second groove line 6, that is, If Δx=Δl, the welded portion 5
is determined to coincide with the first groove line 4. Therefore, there is no deflection of the welding part tip 5a, and it can be easily determined that the desired joining length has been obtained, and there is no need to adjust the irradiation position of the electron beam.

Further, FIG. 3a shows a case where the welding part tip 5a has deviated from the first groove line 4 and is deflected in the opposite direction to the direction in which the transducer 7 is installed. In this case as well, as shown in FIG. 3b, the second groove line 6
The ultrasonic reflected signal 6' from the welding part tip 5a
It is possible to receive an ultrasonic reflected signal 5' from. However, the time difference Δt in the case of FIG. 3 is smaller than that in the case of no deflection as shown in FIG. From this, it can be easily determined that the distance difference Δx is smaller than Δl, and therefore the direction and amount of deflection of the welding part tip 5a can be easily determined, so the irradiation position of the electron beam is adjusted. Become a powerful source of information.

Furthermore, FIG. 4a shows a case where the welding part tip 5a deviates from the first groove line 4 and is deflected in the direction in which the transducer 7 is installed. In this case also the second
Similarly to FIG. 3, the ultrasonic reflection signal 6' from the second groove line 6 and the reflection signal 5' from the welding part tip 5a can be received, but the amount of deflection is large and the unwelded length is If l is large, the reflected signal 4' from the first groove line 4 may also be received. Here, the time difference Δt in FIG. 4b is larger than in the case without deflection in FIG. 2b, and from this it can be easily determined that the distance difference Δx is also larger than Δl. Also, the direction and amount of deflection of the welded portion tip 5a can be easily determined.

Based on the above information sources, Figures 3 and 4
In the case shown in the figure, by adjusting either the irradiation position or the angle of the electron beam so that Δx always becomes equal to Δl during welding, the desired joining length can be stably ensured.

Examples of the present invention will be described below.

FIG. 5a shows an embodiment of the present invention, in which a transducer 7 is attached only to one of the members to be welded.
In butt electron beam welding in which the second groove line 6 detected by the transducer 7
The reflected signal 6' from the welding part tip 5a and the reflected signal 5' from the welding part tip 5a are displayed on the ultrasonic flaw detector 8 as shown in FIG. 5b.

The time difference calculating circuit 9 detects the time difference Δt or the distance difference Δx between the two reflected signals 5' and 6' as shown in FIG. 5b. The time difference or distance difference detected by the circuit is converted by the voltage conversion circuit 10 into a voltage proportional to the time difference or distance difference. Further, the voltage-converted output is amplified via an amplifier 11. The output amplified by the amplifier 11 is input to a comparator 13 that controls the irradiation position of the electron beam 1 so that it becomes a voltage signal of the distance difference Δl, that is, approximately the same value as the reference voltage 12. A switching circuit 14' outputs an output signal from the reference voltage 12 only when it is larger or smaller than the reference voltage 12, and operates a control circuit 14 that controls the irradiation position of the electron beam 1.
is input. The output signal from the control circuit 14 controls a DC deflection coil power supply 15 that deflects the electron beam 1 to the left and right around the first groove line 4, so that the welding part tip 5a always remains in the first groove line during welding. The irradiation position of the electron beam 1 is automatically controlled so as to match the line 4. Here, 16 is a deflection coil, and 17 is an electron gun.

In this example, the desired length Y was 50 mm, so the depth to the penetration tip was 55 mm, and the distance between the first groove line 4 and the second groove line 6 was The difference was 3 mm.

According to the embodiment of the present invention, a desired joint length of 50 mm could be secured over the entire weld length of 3 m. Further, the back side was also welded using the same method.

In this embodiment, the irradiation position of the electron beam 1 is automatically controlled, or the time difference Δt displayed on the ultrasonic flaw detector 8 is visually read and the irradiation position of the electron beam 1 is manually controlled. Of course, this is a good thing.

In addition, in this embodiment, one transducer 7 is disposed on the side surface of the workpiece to be welded, and a vertical flaw detection method in which ultrasonic waves are emitted from the side surface is adopted. This objective can also be achieved by adopting the angle angle flaw detection method in which multiple users are arranged.

As explained above, in the present invention, the tip of the welded part is constantly tracked during welding, so
A major feature is that reliable welds can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view illustrating an example of deflection occurring in an electron beam weld, Fig. 2 a, b, Fig. 3 a, b, and Fig. 4 a, b are the electron beam weld and an ultrasonic echo, respectively. FIG. 5a is a schematic partial cross-sectional view showing an embodiment of the present invention, and FIG. 5b is a diagram showing an ultrasonic echo in the embodiment. 1... Electron beam, 2, 3... Member to be welded, 4
...First groove line, 5... Welded part, 5a... Welded part tip, 6... Second groove line.

Claims (1)

[Claims] 1. Irradiating an electron beam along the first groove line,
In the method of welding while monitoring the relationship between the weld zone and the first groove line generated in the welded material using ultrasonic signals, the reflected signal of the molten zone or the weld zone tip area immediately after melting and solidification is constantly reflected. An electron beam welding method characterized in that a second groove line is provided near the tip of the welding part at a predetermined distance from the first groove line so as to be able to receive the electron beam. 2. Detecting the reflected signal from the molten part or the tip of the welded part immediately after melting and solidification, and the reflected signal from the second groove line, and ensuring that the temporal deviation of the two reflected signals is always maintained at a constant value during welding. 2. The electron beam welding method according to claim 1, wherein the welding is performed while adjusting either the irradiation position or the angle of the electron beam so that the electron beam irradiation position or angle is adjusted.