JPH0514204Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> This invention relates to a welding defect detection and marking device that captures welding defects during welding using a beam of light, detects them online, and is capable of automatically marking the defect location. be.

<Prior art and its problems> Conventionally, X-ray inspection and ultrasonic flaw detection are mainly used after welding is completed as means for inspecting defects after welding.

In FIG. 3, when performing MIG welding on the welded structure 1 and detecting a blowhole 18 or fusion failure 19 as shown in FIG. 4 in the weld bead 4, ultrasonic sensors 16 and 17 are 3, flaw detection was performed at a 45-degree angle across the weld bead 4, and flaw detection was performed along the weld bead line.

If a defect exceeding the tolerance specified by JIS is found,
Repairs by scraping and rewelding were carried out immediately.

For this reason, if a defect exists in a location as shown in Figure 4, the weld bead is cut using a drill or grinder, the defect is removed, repair welding is performed, and stress relief annealing is performed, which is unnecessary work. This is uneconomical, and a certain degree of quality deterioration at the welded repair area is unavoidable.

<Purpose of the invention> The purpose of the invention is to perform on-line defect detection during welding in order to eliminate the drawbacks of the prior art described above.

When performing multi-layer welding of weld beads on thick plate structures using the MIG welding method, this device uses infrared light to monitor welding defects every time a bead is placed, and performs welding work without introducing any welding defects. This is what we propose.

〈Summary of the means〉 This invention uses an optical fiber for infrared rays, which is separate from the visible rays, to receive radiation from the bead immediately after welding, converts it into an electrical signal, and sends it to a device that stores and issues commands. This device detects the bead, sends it to a marking device with an electromagnet, and marks the marker line along the defective part with a template online to facilitate subsequent defect removal.

In short, this device is a device that uses beams of light to detect and treat defects in a heated test object.It is a device that photoelectrically converts visible light emitted by a welding bead in progress and sends it to a comparator as a reference A signal. and,
a device that uses thermovision to detect only infrared rays emitted by the bead and sends it to the comparator as a B signal; and a device that sends a signal to a marking device that marks the position when the voltage difference between the A signal and the B signal exceeds a specified value. This is a welding defect detection and marking device characterized in that it is connected to a welding device.

<Operation> The entire surface of the weld bead is detected using a group of infrared-specific multicore optical fibers with low attenuation in the infrared wavelength region (wavelengths of 800 nm or more), and minute temperature changes on the bead surface are detected using thermovision (for example, AGEMA Thermovision 82).
Natsuku Co., Ltd.) Welding with a function that measures the temperature one after another, compares it with the reference temperature at the arc point, and generates a marker signal to mark the side of the bead when the temperature exceeds the defect evaluation temperature range set by the comparator. The present invention relates to an online defect detection device.

<Example> An example of this invention is shown in FIG. A situation in which multilayer welding is performed on welded structure 1 using the MIG welding method is schematically shown.

A current is applied from the welding power source to the welding wire 10 at the tip of the welding nozzle 3 attached to the welding head 2 while generating an arc between it and the welding structure 1.
MIG welding is done.

When hydrogen, nitrogen gas, rust, etc. are mixed in when an arc occurs, a so-called blowhole occurs in the weld bead 4, where air that has not escaped during the molten metal cooling process forms bubbles and solidifies. As shown in FIG. 4, this blowhole 18 occurs between layers (usually 4 to 6 m/m) each time a bead is placed. In addition, fusion defects 19 may also occur on the side surfaces of the groove, and these are feared as welding defects that can lead to serious accidents if such defects are present in the welded structure.

This invention relates to a device for online monitoring of the above-mentioned defects every time one bead is placed, and will be explained in detail below with reference to FIGS. 1 and 2.

In FIG. 2, an optical fiber 8 attached to the arm of the welding head 2 detects visible light on the bead surface immediately after the arc point and transmits it to a photoelectric converter 11. The photoelectric converter 11 converts the light into a voltage proportional to the intensity of the amount of light.The photoelectric converter 11 converts the light into a voltage proportional to the intensity of the amount of light, and outputs the photoelectric conversion as an input signal to the comparator 14. When welding is performed under appropriate welding conditions, the bead surface temperature immediately after the arc generation point will hardly change as long as the distance between the electrode tip and the optical fiber 8 is constant, and a constant visible light can always be obtained. This is used as the A signal of the comparator 14 as a voltage corresponding to the reference temperature.

On the other hand, at a position 100m/m away from the welding head, a dedicated infrared fiber (3 to 5 multi-core fibers) is installed to cover the entire surface of the bead 4.
Since a multicore fiber is used that detects only components with a diameter of 1μm and inputs it to the thermovision 13, e.g.
Three sets of thermovisions are required to perform photometry in three fields with a core (to reduce the cost, it is technically possible to use only one thermovision unit by incorporating a mechanism for high-speed scanning of three signals).

The thermovision 13 can cover a wavelength range of 800 nm to 1 μm and can perform measurements with a wavelength resolution of 5 nm.

The output from the thermovision is input as the B signal of the next comparator 14, and it is successively compared with the reference temperature A signal mentioned above, and only if the reference temperature set value determined under normal welding conditions is higher or lower than the reference temperature set value, A C signal is generated, and the electromagnetic solenoid 7 is driven by this C signal. This electromagnetic solenoid is a spring type and is normally pulled upward, but when a C signal is input, it can be pulled downward by electromagnetic force.

The tip of this electromagnetic solenoid is TEMPIL (product name: colored plastic material 30℃) used for preheating temperature control during welding.
Approximately 30 types of pituchi (with temperatures ranging from 70℃ to 800℃)
I installed it and colored the side of the bead.

In this way, it is possible to automatically mark the defect position online on the bead side surface of the welded structure 1 at the same time as the defect occurs.

When the above-mentioned device is applied to actual narrow-gap MIG welding, with conventional means, a non-destructive inspection is performed after the final welding is completed, and if a welding defect is found, it is cut with a grinder or drill and repair welding is performed. Become. Once such a welding defect occurs in an extremely thick structure such as a boiler header or a reactor pressure vessel, the repair work will take several tens of days, and the quality of the repaired welded area will inevitably deteriorate. In addition, repairs involve wasteful work such as heat treatment (tempering work, redoing non-destructive testing).

By implementing this idea, narrow gap MIG
When carrying out multi-layer welding of extremely thick structures using the welding method, by continuously monitoring the entire welding process from the initial bead to the final bead, we can perform multi-layer welding while confirming that there are no welding defects. This method has the advantage of eliminating the need for back-up work associated with repairs, which is required with conventional methods.

<Effects> By implementing this invention, in the conventional technology, non-destructive inspection could not be performed until after welding was completed, but by applying the present invention, non-destructive inspection can be carried out sequentially in parallel with welding work, and welding Since defects can be detected at each interlayer welding stage, high-quality welding is possible, reducing manufacturing man-hours, improving the reliability of welded structures,
It has the effect of being able to measure energy consumption.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the device according to this invention, Figure 2 is a perspective view of the device according to this invention;
The figure is a side view of the device showing its control circuit, Figure 3 is a perspective view showing conventional defect detection using ultrasonic waves, and Figure 4 is a side view of the device showing its control circuit.
The figure is a partial cross-sectional perspective view of a welded part schematically showing welding defects such as blowholes and poor fusion. 2... Welding head, 3... Welding nozzle, 4...
Welding bead, 5... Marker line, 6... Tenpil, 7... Electromagnetic solenoid, 8... Optical fiber, 9... Infrared dedicated fiber, 14... Comparator (device for storing and issuing command signals).

Claims (1)

[Scope of utility model registration request] A device for detecting and treating defects in a heated test object using radiant light, comprising: a device for photoelectrically converting visible light emitted by a welding bead in progress and sending it to a comparator as a reference A signal; A welding device includes a device that sends a B signal to the comparator using thermovision that detects only infrared rays, and a device that sends a signal to a marking device that marks the position when the voltage difference between the A signal and the B signal exceeds a specified value. A welding defect detection marking device characterized in that it is connected and provided.