JPH11314155A - Predictive diagnostic method of weld crack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable welding operation to be efficiently performed without causing weld crack by predicting its generation in advance. SOLUTION: This method is such that the fixed conditions are varied consisting at least of a welding base material component and a wire component which are the cause of weld crack in a weld zone, that the variable conditions are also varied consisting at least of a welding current and a welding speed, and that a model is prepared for the generation of weld crack under each of these conditions and inputted preliminarily in an arithmetic unit 7. Then, the fixed conditions 8, 9 under which welding is intended at present are inputted in the arithmetic unit 7, while the variable conditions are measured in real time, with the measured signals 10, 11 inputted in the arithmetic unit 7 and compared with the models for the generation of weld crack. The generation of weld crack is thereby predictively diagnosed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for predicting and diagnosing welding cracks.

[0002]

2. Description of the Related Art FIG. 3 shows a TIG welding machine as an example of a welding method, in which a TIG welding machine 1 and a base material 2 are relatively moved (in FIG. 3, the TIG welding machine 1 is moved in the direction of arrow X). Then, while supplying the shielding gas 5 to the welding torch 3 so as to surround the outer periphery of the electrode 4 and feeding the wire 6 and supplying power to the electrode 4 (control of voltage and current), weaving of the welding torch 3 is performed. As shown by the arrow Y in FIG. 3, the welding torch 3 is reciprocated in the left and right directions with respect to the moving direction X).

[0003] When performing a welding operation using the above-described welding machine, it is very important to perform the operation so as not to cause a welding defect in a welded portion.

In general, in welding, good welding quality can be obtained by monitoring and appropriately controlling parameters such as welding voltage, welding current, welding speed, wire feeding speed, weaving speed, weaving width, and shielding gas flow rate. Working to get it.

However, at present, welding defects are generated due to various factors.

[0006] Weld defects include irregular bead, large and small bead, large and small bead height, pits, welded metal surface defects such as oxidation, undercuts, overlaps and other boundary (surface) defects with the base material, porosity. Defects in the weld metal, such as welding, tungsten inclusions, fusion defects, insufficient penetration, etc. at the boundary with the base metal (internal), and weld cracks (high-temperature cracks and low-temperature cracks) that occur in the weld after welding. Can be

[0007] The welding cracks generated in the conventional welding method include fixed conditions such as welding base metal components, wire components, base metal restraining conditions, and preheating temperatures, welding current, welding speed, and welding voltage. In addition, the frequency of occurrence greatly changes depending on fluctuation conditions such as weaving speed and shielding gas amount.For this reason, conventionally, test welding was performed every time the above fixed conditions and fluctuation conditions were changed, and it was confirmed that welding cracks did not occur. After confirming, the welding work was performed.

[0008]

However, in the conventional method, test welding is carried out every time the fixed condition or the fluctuating condition changes, and after confirming that no welding cracks have occurred, the welding operation is performed. Therefore, there is a problem that the welding operation is complicated and the work efficiency is deteriorated, and there is a problem that the material is wasted for the test welding.

In addition, in order to prevent the occurrence of welding cracks, there is a problem that welding is actually performed at an unnecessarily low speed or the like, and the working efficiency is further reduced. .

[0010] Further, when the above-mentioned fluctuation conditions change during the welding operation, there is a problem that a large number of weld cracked products are produced.

SUMMARY OF THE INVENTION The present invention has been made to solve the conventional problems, and it is intended to predict the occurrence of welding cracks in advance and to perform welding work efficiently without causing welding cracks. The purpose of the present invention is to provide a predictive diagnosis method.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a fixing condition comprising at least a welding base metal component and a wire component, which is a factor of causing a welding crack in a weld, is changed, and at least a fluctuating condition comprising a welding current and a welding speed. Is changed, a model of the occurrence of welding cracks under each condition is created and input to the arithmetic device in advance, the current fixed condition to be welded is input to the arithmetic device, and the fluctuation condition is measured in real time. And a method for predicting and diagnosing the occurrence of weld cracks by inputting the measurement signal to the arithmetic unit and comparing the measured signal with the model for the occurrence of weld cracks.

According to the above means, welding can be performed stably.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a control block for carrying out the method of the present invention. The control block includes at least a welding base metal component and a wire component (if necessary, the preheating temperature is a factor that causes a weld crack in a welded portion). ), And a plurality of test weldings in which at least the fluctuation conditions consisting of the welding current and the welding speed are changed are performed. A model of welding crack occurrence is created and stored in the arithmetic unit 7.

As the fixing condition, a welding base metal component and a wire component which have a great influence on the occurrence of welding cracks are always used, and in addition, a preheating temperature, a base material constraint condition, and the like may be used.

As the fluctuation conditions, a welding current and a welding speed which greatly affect the occurrence of welding cracks are always used, and in addition, a welding voltage, a weaving speed, a shielding gas amount and the like may be used. .

At the time of carrying out the welding operation, for example, the welding base metal component 8 and the wire component 9 which are the fixed conditions to be welded are input to the arithmetic unit 7, and further, the welding condition which is the variation condition of the welding machine 1, for example, The current and the welding speed are measured in real time, and the measurement signal 10 of the welding current and the measurement signal 11 of the welding speed are input to the arithmetic unit 7.

The arithmetic unit 7 calculates welding conditions based on the welding base metal component 8 and the wire component 9 which are input fixed conditions and the welding current measurement signal 10 and welding speed measurement signal 11 which are variable conditions. The model is compared with a model of welding crack occurrence which is input and stored in the device 7 in advance, and the occurrence of welding crack is predicted and diagnosed by this comparison.

The diagnostic signal 12 predicted and diagnosed by the arithmetic unit 7
Is output to the display 13 for displaying or warning.

Further, a control for outputting the diagnostic signal 12 to the welding machine 1 and automatically adjusting the welding current and the welding speed, which are the above-mentioned fluctuation conditions, so as not to cause welding cracks in accordance with the predicted diagnosis result is performed. It may be performed.

FIG. 2 is a graph showing an example of the model of the occurrence of welding cracks, and is a graph in which the crack rate when heat input was changed in D347 (stainless steel) was tested.

According to FIG. 2, the heat input is 0.4 (A / mm /
min), the cracking rate was 95%, and when the heat input was 0.9 or more, the cracking rate was reduced to 20%. This is hot cracking due to reduced heat input.

It is also known that, even when the welding voltage is changed, a welding crack occurs when the voltage exceeds a predetermined voltage, as in the case of the welding current.

As described above, a model of crack generation obtained by variously changing the fixed condition and the fluctuating condition is input to the arithmetic unit, and at least the welding base metal component and the wire component, and at least the welding current and the welding speed are obtained. By inputting the measurement signal of the above to the arithmetic unit and comparing it with the model of the occurrence of weld cracks stored in the arithmetic unit, the occurrence of weld cracks is predicted and diagnosed. The occurrence can be predicted and diagnosed, so that the fluctuating condition can be corrected and the welding operation can be performed under the welding condition with the highest operation efficiency without causing the welding crack.

[0026]

According to the present invention, a crack generation model obtained by variously changing the fixed condition and the variable condition is input to an arithmetic unit, and at least the welding base metal component and the wire component, and at least the welding current By inputting the measurement signal of the welding speed and the calculation device to the arithmetic device and comparing it with the model of the occurrence of welding cracks stored in the arithmetic device, the occurrence of welding cracks is predicted and diagnosed, so that the accuracy is high. It is possible to predict and diagnose the occurrence of welding cracks, and thus to achieve an excellent effect that the welding operation can be performed without causing welding cracks under the welding conditions with the highest operating efficiency by correcting the fluctuation conditions. .

[Brief description of the drawings]

FIG. 1 is a control block diagram for implementing a method for predicting and diagnosing welding cracks according to the present invention.

FIG. 2 is a graph showing an example of a model of welding crack occurrence.

FIG. 3 is a schematic sectional view showing an example of a TIG welding machine.

[Explanation of symbols]

 7 arithmetic unit 8 welding base metal component (fixed condition) 9 wire component (fixed condition) 10 measurement signal of welding current (variation condition) 11 measurement signal of welding speed (variation condition)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirofumi Yamatori 1st Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Ishikawashima-Harima Heavy Industries Co., Ltd. 1 Nakaharacho Ishi Kawashima Harima Heavy Industries Co., Ltd. Yokohama Engineering Center

Claims (1)

[Claims] At least one of the following conditions: a fixing condition comprising at least a welding base metal component and a wire component, which are factors that cause welding cracks in a welded portion; A model of the occurrence of welding cracks is created in advance and input to the arithmetic unit in advance, the current fixed conditions to be welded are input to the arithmetic unit, and the fluctuation condition is measured in real time, and the measurement signal is sent to the arithmetic unit. And predicting and diagnosing the occurrence of a weld crack by comparing the model with the model for the occurrence of a weld crack.