JPS6224863A - Detecting method for tack bead buildup on groove for fillet welding - Google Patents

Abstract

PURPOSE:To improve a detecting accuracy by integrating the variation of arc voltage, etc. over the prescribed range and by comparing it with the reference value and by detecting a tack weld bead based on the comparison difference thereof. CONSTITUTION:An arc voltage detector 7, integrator 8 are provided and a reference voltage setter 15 is arranged as well. A bead is formed between an electrode and groove with turning a welding electrode. In this case the voltage between the electrode and groove is detected by the arc voltage detector 7 and inputted it to the integrator 8 as well. The integrator 8 integrates the variation in the arc voltage in the set range by integration range setters 11, 12. The reference voltage S1 of the time when the tack weld bead is not built up is then set to a setter 15 and the difference DELTAE in the integration value S2 and reference voltage S1 is detected by a differential amplifier 14 as well. With this method the presence of the tack weld bead and bead height can be detected. The detecting accuracy is therefore increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for detecting a tack bead formed in a groove for fillet welding.

[Prior art and its problems]

As a method for fillet welding a vertical plate and a horizontal plate, the inventors of the present application previously proposed a rotating arc fillet welding method, for example, in Japanese Patent Application No. 88732/1988 (hereinafter referred to as the prior invention). The prior invention will be described in detail below. As shown in FIG. 1, in the prior invention, the nozzle 3 is directed toward the groove formed by the vertical plate 1 and the horizontal plate 2, and the welding electrode 4 is deviated from the central axis of the nozzle 3 to reach the groove. While rotating the nozzle 3 at a predetermined speed, an arc is generated between the welding electrode 4 and the groove to form a bead 5, and the rotation direction, rotation speed, and rotation diameter of the arc are It consists of limiting as follows.

Arc rotation direction: When the vertical plate 1 is placed on the right side when facing the welding direction, the arc rotation direction is clockwise rotation when viewed from the top of the nozzle 3, and perpendicular to the left side when facing the welding direction. When plate 1 is placed, the rotation direction of the arc is left rotation (counterclockwise rotation) when viewed from the top of nozzle 3.
, Arc rotational speed: The rotational speed at which the ratio (4/22) of the bead width on the vertical plate 1 side, that is, the vertical leg length (Ll), and the bead width on the horizontal plate 1 side, that is, the horizontal leg length Ω2) is maximum. , Arc rotation diameter: 1-6 orders.

The reason why the direction of rotation of the arc is limited as described above is to scoop up the molten metal that hangs down due to gravity and to achieve equal length.

The rotational diameter of the arc is limited to a range between 1 and 6.
Due to the following reasons.

If the rotational diameter of the arc is less than 1 mm, sufficient penetration cannot be obtained and the function of rotating arc welding cannot be fully demonstrated. Furthermore, in the rotating arc fillet welding method, groove tracing is performed as follows. That is, the fluctuation value of either one of the arc current and the arc voltage is detected, the detected fluctuation value is integrated over equal ranges to the left and right, centering on the most forward point in the welding direction of the welding electrode, and then The nozzle is moved in the width direction of the bead so that the difference between the integral values becomes zero. Hereinafter, this method will be referred to as groove copying using an arc sensor, but if the rotating diameter of the arc is less than IU, even if the center of rotation of the arc deviates from the normal position, the difference between the integral values on the left and right sides will be significant. Therefore, it is not possible to accurately trace the groove using the arc sensor.

On the other hand, when the rotating diameter of the arc exceeds 6IIJ, the arc approaches the vertical plate 1 and the horizontal plate 2 too much, and undercuts are particularly likely to occur on the vertical plate 1 side. For this reason, the rotating diameter of the arc was limited to a range of 1 to 61 mm.

However, the above-mentioned prior art had the following problems. That is, as shown in FIG. 2, if the bead 6 is formed on the bevel, the shape of the bead deteriorates and the beveling and tracing by the arc sensor described above cannot be carried out with high accuracy.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a method that can easily and reliably detect the bead of tack welded in the groove when fillet welding a vertical plate and a horizontal plate using a rotating arc. There is a particular thing.

[Summary of the invention]

In this invention, a nozzle is directed toward a groove formed by a vertical plate and a horizontal plate, a welding electrode is deviated from the central axis of the nozzle, and a shielding gas is supplied toward the groove, and the nozzle is rotated. An arc is generated between the welding electrode and the groove while performing fillet welding between the vertical plate and the horizontal plate, and each rotation of the nozzle increases either the arc voltage or the arc current. A fluctuation value is detected, the fluctuation value thus detected is integrated over a predetermined range including the forwardmost point of the nozzle in the welding direction, and the integral value thus obtained is combined with a preset reference value. The difference between the two is calculated, and the bead of the tack applied to the groove is detected based on the difference.

[Structure of the invention]

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

FIG. 3 is a block diagram of one embodiment of the invention.

In FIG. 3, an arc voltage detector 7 detects the voltage between the groove and the welding electrode rotating at a predetermined speed, that is, the arc voltage. The integrator 8 selects a predetermined integration range (-φ.~
Tenφ. ) is integrated according to a command signal from a controller, which will be described later. Controller 9 sends a command signal to start and stop integration to integrator 8 based on the electrode position signal from welding electrode position detector 10 . The integral range setter 11 and the integral number setter 12 preset the integral range and the number of integrals in the controller 9, respectively. Memory device 1
3 stores the integral value of the arc voltage integrated by the integrator 8. Then, the differential amplifier 14 calculates the difference between the integral value stored in the memory 13 and a reference voltage preset by the reference voltage setter 15.

The arc voltage (g
) is minimum when the welding electrode approaches the vertical plate and the horizontal plate, as shown by the dotted line in Fig. 4 (A), and when the welding electrode approaches the groove root ((○) in Fig. 5
Indicated by ) is maximum when located above. Figure 4 (A
) The position of the welding electrode at (Cr), (L),
(Cf) and (R) will be explained. As shown in Figures 5 and 6, (cr) refers to the direction of welding progress (in Figure 5, from the back of the page to the front,
In the figure, the rearmost point is shown (leftward from the sheet cloth), (L) is the point where the welding electrode 4 is closest to the horizontal plate 2, and (C'f) is the welding progress. With respect to the direction
The forwardmost point is shown, and (R) shows the point where the welding electrode 4 is closest to the vertical plate 1.

Note that FIG. 6 shows the position of the welding electrode 4 viewed from the upper end of the nozzle 3. The central axis U> of the nozzle 3 is perpendicular to the root (0) of the groove, and is at an angle of 4 with respect to the horizontal plate 2.
It is tilted at 5°.

Here, if we assume that the bead is piled up on the bevel,
The arc voltage (Pi) decreases significantly at point (Cf), as shown by the solid line in FIG. 4 (A). Second,
If the integral range of the arc voltage (E) is set to the range (-φ. to 10φG) centered on the above point (Cf), then the integral value of the arc voltage (S
1) and the integral value (S2) of the arc voltage when the bead is piled up during tack attachment.

For this reason, when tacking, if the integral value (S,) of the arc voltage when no bead is built up is set in advance in the reference voltage/voltage setting device 15 as the reference voltage, then tacking can be done without a bead. , the differential amplifier 14 outputs a voltage (
ΔF, ) occurs. Therefore, by detecting the voltage difference (ΔF), it is possible to determine the presence or absence of a bead during tacking.

Furthermore, the height of the temporary attachment can be detected based on the magnitude of the voltage difference (ΔF).

The range of the integral range (-φ to +φ) preset in the controller 9 is preferably in the range of 10° to 360°.

When the number of integrations is set to a plurality of times by the number of integrations setter 12, the reference voltage is also set to a value obtained by multiplying the integral value (Sl) by a number of times. In this case, each time the nozzle 3 rotates a plurality of times, a bead is detected during tacking.

The above description is based on the case where the arc voltage (E) is used to detect a bead during tack-fitting, but the arc current (I) may also be used to detect a bead during tack-fitting. In this case, the arc current (1) changes as shown in FIG. 4(B). In addition, the welding electrode 4 in this invention may be either consumable or non-consumable.

〔Effect of the invention〕

As explained above, according to the present invention, when performing fillet welding between a vertical plate and a horizontal plate using a rotating arc, it is possible to easily and reliably detect a bead in the tacking formed in the groove. This brings about useful effects such as:

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing fillet welding according to the prior invention, Fig. 2 is a sectional view of the groove where the tack weld is applied, and Fig. 3 is an embodiment of the present invention. 4(A) is a graph showing the relationship between welding electrode position and arc voltage, FIG. 4(B) is a graph showing the relationship between welding electrode position and arc current, and FIG. 5 is a block diagram of the embodiment. , a front view showing the position of the welding electrode, and FIG. 6 is a plan view of the same. In the drawings, 1...vertical plate, 2...horizontal plate,
3... Nozzle, 4... Welding electrode, 5...
... Bead, 6...7 Temporary attachment is bead, 7
... Arc voltage detector, 8... Integrator, 9... Controller, 1, 10... Welding electrode position detector, 11...
・Integration range setter, 12...Integration number setter, 13
...Memory device, 14...Differential amplifier, 15
...Reference voltage setting device.

Claims (1)

[Claims] A nozzle is directed toward a groove formed by a vertical plate and a horizontal plate, a welding electrode is deviated from the central axis of the nozzle, and is supplied together with a shielding gas toward the groove, while the nozzle is rotated. Generating an arc between the welding electrode and the groove to perform fillet welding between the vertical plate and the horizontal plate, and varying the value of either the arc voltage or the arc current for each rotation of the nozzle. The fluctuation value thus detected is integrated over a predetermined range including the forwardmost point in the welding direction of the nozzle, and the integral value thus obtained is compared with a preset reference value. Detection of a tack bead built up in a groove for fillet welding, characterized by calculating a difference between the two, and detecting a tack bead built up in the groove based on the difference. Method.