JPH0687081A - Method and device for controlling seam welding quality - Google Patents

Abstract

PURPOSE:To automatically carry out total inspection on the whole weld line by carrying out follow-up probing on a weld zone welded by a preceding electrode ring at a specified distance by a probe for ultrasonic flaw detection. CONSTITUTION:In the method where two metal plates are subjected to lap seam welding, an ultrasonic detection means 10 is provided on a rear part of the electrode ring 5 for seam welding. This detection means 10 detects momently the ultrasonic wave reflectivity of the weld zone while following a butt part welded by the above proceding electrode 5. When the detected ultrasonic wave reflectivity exceeds a preset reference value (or when the detected ultrasonic wave reflectivity does not exceed the reference value), an output signal is produced to the outside. Consequently, the quality can be determined right after welding and efficiency and reliability of quality inspection of the seam weld zone can be increased. In addition, the probe is moved repeatedly at the specified speed by the wed bead width in the orthogonal direction to a weld line to carry out probing in the whole range of the weld line, by which welding quality control accuracy of the whole weld zone including the weld bead width is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding quality control method and apparatus for a seam welder, which determines the quality of a welded portion simultaneously with the seam welding operation.

[0002]

2. Description of the Related Art In the conventional seam welding, the quality of the welded portion is judged
It was performed by periodically extracting welded pieces and performing a destructive inspection or a cross-section inspection, and judging from the inspection results whether the welding conditions, control, and the condition of the welded object are kept within an appropriate range.

[0003]

However, in such a sampling inspection, destructive inspection is troublesome and the work is damaged. We cannot perform 100% inspection of welds. Should a welding defect be discovered, there was a problem in that it was necessary to doubt the wide range of welded materials up to the last extraction point.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and two metal plates are superposed by a predetermined amount, and a pair of abutting portions formed by superposing the metal plates are formed. In a seam welding method, which is sandwiched between electrode wheels for seam welding, and is butt-welded while applying a pressing force and a current required for welding to the electrode wheels while rotating the electrode wheels, ultrasonic detection means is provided at a rear portion of the electrode wheels. The ultrasonic wave reflectance of the welded portion is detected moment by moment while tracking the butt portion welded by the electrode wheel preceded by this detection means, and the detected ultrasonic wave reflectance is a preset reference value. The main feature is a method of outputting an output signal to the outside when the value exceeds (or does not exceed) the value.

Further, the following technical means are taken as an apparatus for carrying out the method of the present invention. That is,
A seam welding machine in which two metal plates facing each other in a butt state are overlapped by a predetermined amount, the overlapped butt portion is pressed by a pair of seam welding electrode wheels, and this is rotationally driven to energize for welding. In one, a trolley, a pair of seam welding electrode wheels supported by the trolley, and a rear portion of the electrode wheel, which are repeatedly operated in the welding bead width direction of the welded butt portion, Detects the ultrasonic reflectance of the butt welded by the seam welding electrode wheel,
And an ultrasonic wave detecting means for outputting an output signal to the outside when the detected ultrasonic wave reflectance exceeds a preset reference value.

[0006]

Therefore, in the system of the present invention, the ultrasonic detecting means is provided at the rear portion of the electrode of the carriage for holding the seam welding electrode wheel, so that the detecting means can keep the welding portion made by the preceding electrode wheel constant. It will be tracked and explored at a distance of. Therefore, as compared with the conventional sampling inspection method, the quality of the welded portion can be automatically determined during welding. All weld lines can be inspected immediately after welding and can be searched in the weld bead width direction, improving quality control accuracy and establishing a highly reliable quality control system.
Further, since it is a non-destructive inspection, no special inspection process or drive device for inspection is required. Therefore, the welding quality control device can be manufactured with a simple structure and at a low cost.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mash seam welding machine when the method of the present invention is carried out will be described below with reference to the drawings. Note that FIG. 1 is a schematic view of the entire apparatus of the present invention.
FIG. 2 is an explanatory view showing the positional relationship between the seam welding electrode wheel, the ultrasonic detecting means, and the welded portion. Further, FIG. 3 shows an operation locus of the detecting means oscillator.

Reference numeral 1 denotes a C-frame carriage, in which a roller 2 is driven by a cylinder 4 along a guide 3 and moves forward and backward from a direction intersecting at right angles with the line direction of the metal plate S. Reference numeral 5 denotes a pair of upper and lower seam welding electrode wheels, and a pressure cylinder 6 performs pressure / opening operation between the electrodes. 7 is a welding transformer. Reference numeral 8 is a secondary conductor that constitutes an energization path between each electrode wheel and the welding transformer 7. These are structural parts that are no different from conventional ones.

Reference numeral 10 is an ultrasonic flaw detection probe used as ultrasonic detection means. For example, as shown in the figure, the secondary conductor 8
It is attached to the rear part of the electrode wheel in an insulated state. In this case, the probe is not in contact with the metal plate and may be arranged on the upper side or the lower side. Alternatively, the surface of the weld may be directly contacted. Further, in order to improve the transmission efficiency of ultrasonic waves and to avoid damage to the probe due to heat, it is covered with a pipe P filled with jet water. In the flaw detection data detected by the probe 10, since the distance from the probe to the metal plate and the work plate thickness are known in advance, the metal plate of the work piece to be welded can be calculated by calculating the sound velocity and the delay time of the reflected wave. It is possible to judge and cancel reflected wave components from the front and bottom surfaces. Since ultrasonic waves are almost totally reflected when there is a hollow inside such as a blowhole, the magnitude of the reflected wave from the inside of the weld, which is between the work surface and the bottom surface, is closely correlated with internal defects.

Then, the detected flaw detection data is compared with a predetermined reference value (upper limit or lower limit) to be judged as pass / fail,
If an output signal such as an alarm is output to the outside when the detected value exceeds the reference value or does not reach the reference value, highly reliable welding quality control becomes possible. Even if ultrasonic flaw detection is highly reliable, it is not necessary to independently perform ultrasonic flaw detection on all long welding lines after welding, either manually or with a scanner device, in terms of man-hours and time. There was a problem. However, as in the present invention, by arranging the probe on the carriage equipped with the electrode wheel for welding,
It becomes possible to solve these problems all at once.

Next, in the embodiment of the method described above, the probe 1
The scanning direction of 0 was one-dimensional, and so to speak, only one cross section in which the central portion of the welding line was divided vertically was the object of inspection. In reality, it can be said that this almost represents the quality of the weld. However, to be more precise, since the bead width of normal mash seam welding is about 4 to 8 mm,
It is necessary to inspect the overall welding quality three-dimensionally, including in the bead width direction. Therefore, the probe mounted on the carriage is repeatedly moved at a constant speed in the direction perpendicular to the welding line by the width of the welding bead, and in addition to the plate thickness direction, the welding bead width direction is also searched to detect all welds. The quality can be surely inspected.

[0012]

As described above, according to the method of the present invention, the ultrasonic detection means such as the ultrasonic flaw detection probe is provided at the rear portion of the electrode of the carriage for holding the seam welding electrode wheel. The probe will trace and search the welded portion performed by the preceding electrode wheel at a constant distance. Therefore, compared to the conventional sampling inspection method, all the weld lines can be automatically inspected and the quality can be determined immediately after welding. This can significantly increase the efficiency and reliability of seam weld quality inspection.

Further, the apparatus of the present invention repeats the movement of the probe in the direction perpendicular to the welding line by the width of the welding bead at a constant speed to search the entire range of the welding portion, and thus the welding portion including the welding bead width. Improves overall welding quality control accuracy. Also, because it is a non-destructive inspection, a special process for inspection,
No drive unit required. The probe can be easily added to the existing seam welder, and the structure is simple and the manufacturing cost is low.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an apparatus for carrying out the method of the present invention.

FIG. 2 is an explanatory diagram showing a positional relationship between a seam welding electrode wheel, ultrasonic detecting means, and a welded portion.

FIG. 3 is a diagram showing an operation and a locus of the probe oscillator.

[Explanation of symbols]

 1 trolley 5 Seam welding electrode 10 Ultrasonic detection means (ultrasonic flaw detection probe) S Metal plate

Claims (2)

[Claims] 1. Stacking two metal plates by a predetermined amount,
In the seam welding method, the butt portion formed by superposition is sandwiched by a pair of seam welding electrode wheels, and the electrode wheels are subjected to butt welding while being rotationally driven by applying the pressure and current required for welding. , Ultrasonic detection means is provided at the rear portion of the electrode wheel, and the ultrasonic reflectance of the welded portion is detected moment by moment while the detection means follows the butted portion welded by the preceding electrode wheel, A seam welding quality control method characterized in that an output signal is output to the outside when the detected ultrasonic reflectance exceeds (or does not exceed) a preset reference value. 2. A pair of two metal plates facing each other in a butt state are superposed by a predetermined amount, and the superposed butt portions are pressed by a pair of seam welding electrode wheels, which are rotatively driven and energized for welding. In a seam welding machine for carrying out the above, one dolly, a pair of seam welding electrode wheels supported by the dolly, and a butt portion welded at the rear portion of the electrode wheels are repeatedly welded in the width direction of the weld bead. It operates and detects the ultrasonic reflectance of the butt welded by the preceding seam welding electrode wheel, and outputs an output signal to the outside when the detected ultrasonic reflectance exceeds a preset reference value. Seam welding quality control device with ultrasonic detection means.