JPH09281090A - Inspection of in-line welded part of metal strip and in-line welding apparatus for metal strip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect acoustic radiation to judge the healthiness of a welded part by applying a force in the direction opposite to a strip feed direction and/or a force in the strip feed direction to a strip after in-line welding. SOLUTION: A metal strip 1 passes through a looper 9 from a pay-off reel 2 through an inlet pinch roll 3, a welding machine 5 and an outlet pinch roll 6 to continue to the treatment line of a post-process. Acoustic radiation is detected by acoustic radiation sensors 7a, 7b to be subjected to signal processing by an acoustic radiation signal processor 8. The rear end of the strip 1 enters a shearing machine 4 and the crop thereof is cut and the strip 1 is stopped at the position of the welding machine 5. In the judgment of the strength of a welded part utilizing acoustic radiation, the tension corresponding to test load is applied to the strip 1 by the pinch rolls 3, 6. Acoustic radiation is detected by the acoustic radiation sensors 7a, 7b brought into contact with the metal strip in the vicinity of the welded part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line weld inspection method and an in-line welding apparatus for a metal strip, which is carried out on the inlet side of a continuous processing line for a metal strip such as steel.

[0002]

2. Description of the Related Art Pickling of metal strip, continuous cold rolling,
In processes such as continuous annealing, strip heading is complicated and the process conditions become unsteady at the front and rear ends, resulting in quality deterioration. The tip of the material is welded and passed through. If there is a defect in this welded portion, plate breakage occurs in the subsequent process, and not only the material is scrapped but also the equipment is damaged, resulting in a large loss such as a lost production opportunity. In order to prevent such a situation, in-line inspection of the welded portion is performed.

The inspection method is as follows:
In 973 and Japanese Utility Model Laid-Open No. 3-70885,
A method for evaluating the weld by incorporating an Erichsen tester in-line is described. In addition to this, a method is widely used in which a weld is hit and inspected for cracks. In Japanese Utility Model Application Laid-Open No. 3-70885, automatic hitting is also described. Further, Japanese Patent Application Laid-Open No. 6-34564 describes a method of determining the quality of welding by detecting the temperature distribution of the welded portion and performing image processing.

[0004]

However, since the Erichsen test is a destructive test, only the representative points are inspected and the entire length of the welded portion cannot be inspected. Further, with the inspection method disclosed in Japanese Utility Model Laid-Open No. 3-70885 that hits a welded portion, it is difficult to perform a quantitative evaluation. Further, in the determination method for image-processing the temperature distribution of the welded portion disclosed in Japanese Patent Laid-Open No. 6-34564, the equipment is expensive because a lot of calculation is required for data processing, and the strength is not directly inspected. Since there is no, the judgment algorithm is complicated,
Development may take a long time.

Further, all of the above-mentioned conventional inspection devices are installed on the rear surface of the welding machine in order to avoid interference with the welding machine, and the welded strip is once moved to the inspection position,
There is a problem that the cycle time becomes long because it is necessary to perform positioning and stop. On the rear side of the welding machine, there is a device called a looper that temporarily stores strips so that the processing line does not need to slow down during welding and inspection work. This also causes a problem that the looper becomes large in size in combination with the increase in the speed, so it is necessary to shorten the time for combining welding and inspection as much as possible.

As described above, conventionally, it has been difficult to quantitatively determine the strength of the welded portion in a short time with inexpensive equipment.
Therefore, the present invention solves the above-mentioned problems, and provides an in-line welded portion inspection method and welding device for a metal strip that can determine the strength of a welded portion quantitatively in a short time with inexpensive equipment, and with high reliability. To do.

[0007]

A welding portion inspection method of the present invention is a welding portion inspection method which is performed subsequent to in-line welding on the inlet side of a continuous processing line of a metal strip, and is a direction opposite to the strip conveying direction after the in-line welding. An in-line weld inspection method for metal strips, characterized by applying a force in a direction and / or a force in a strip transport direction to a strip to detect acoustic radiation to determine the integrity of the weld.

Further, the welding apparatus of the present invention is a means for applying a force to the strip in the direction opposite to the strip conveying direction on the front surface of the welding machine in the in-line welding apparatus on the inlet side of the continuous processing line for metal strips, and / or An in-line welding device for a metal strip, comprising means for applying a force to the strip in the strip conveying direction on the rear surface of the welding machine, and further comprising acoustic radiation detection means and acoustic radiation signal processing means. A pay-off reel device can be used as a means for applying a force to the strip in a direction opposite to the strip transport direction. Further, as means for applying a force to the strip in the direction opposite to the strip conveying direction on the front surface of the welding machine and / or means for applying a force in the strip conveying direction on the rear surface of the welding machine to the strip, the strip positioning of the welding machine is performed. A clamping device for can be used.

A method of inspecting the strength of a structure by applying a test load higher than the load during use and judging whether or not it breaks is known as a proof test.
However, with this method, if the test load is too large, it may cause the breakage of sound members, and even if the breakage does not occur, quantitatively grasp how much strength margin there is. There is a drawback that you cannot do it. Therefore, in the present invention, attention is paid to acoustic emission as a method of detecting a sign of breakage. Since acoustic radiation occurs due to the plastic deformation of metal materials and the development of fine cracks, the radiation amount increases at a load lower than the breaking load as illustrated in FIG. When the structure ruptures, before the macro-rupture of the entire structure, the stress concentration in the defect part locally exceeds the yield stress and a microcrack progresses, and acoustic radiation is detected even at low test loads. By doing so, it is possible to quantitatively inspect the margin until breakage. Further, since the test load is lower than the breaking load, damage such as crack growth due to the test is slight, and the overall strength is not reduced. Furthermore, because the margin of strength can be quantitatively grasped, it is possible to immediately detect the time-series deterioration of the welding machine, which does not pose a problem, and to carry out early repair or
Welding reliability can be improved by adjustment.

[0010]

Embodiments of the present invention will be described below.

FIG. 1 is a configuration diagram of a line in which the welding apparatus of the present invention is installed. The metal strip 1 is connected from the payoff reel 2 to the processing line of the subsequent process through the entrance side pinch roll 3, the welding machine 5, the exit side pinch roll 6 and the looper 9. The acoustic radiation is detected by the acoustic radiation sensors 7a and 7b and processed by the acoustic radiation signal processing device 8. The shearing machine 4 trims the front and rear ends of the metal strip 1 before welding, and may be on the front side or the rear side of the entry side pinch roll 3 as long as it is before the welding machine 5.

The rear end of the metal strip 1 stops in the welder 5 after the crop has been cut by the shears 4.
Next, another coil is set on the pay-off reel 2, and after the tip crop portion is sheared, it is guided to the welding machine 5, where the trailing edge of the preceding material and the leading edge of the following material are welded, and the extra beads are cut. To be done.

In the present invention, the strength of the welded portion is determined by utilizing acoustic radiation, and tension corresponding to the test load is applied to the metal strip 1 by the entrance side pinch roll 3 and the exit side pinch roll 6. In this embodiment, the test load is set to 10 to 50% of the breaking load of the normally welded portion. However, the test load can be changed according to the composition of the material, the size, the degree of processing to be performed in the post process, and the like. The acoustic radiation is emitted by the acoustic radiation sensors 7a, 7b which are brought into contact with the metal strip 1 near the weld.
To detect. The sensor may be provided in one place, but a method has been established in which it is installed in two or more places to identify the generation position based on the arrival time difference, etc. By using this, highly reliable inspection with less noise becomes possible. Note that the acoustic emission sensor does not necessarily have to be installed between the tension applying devices.

In this method, the welded portion does not need to be exposed to the outside and can be inspected without moving the metal strip from the welding position, so that there is no time loss due to movement / positioning and a time cycle is reduced. It will be shortened. At the time of inspection, since the metal strip moves only by the change in elastic elongation and slack due to tension, it is possible to use a commonly used contact type inexpensive sensor also as an acoustic emission sensor, and the vibration due to the movement of the metal strip is also small. No disturbance to acoustic radiation.

The means for applying a tension to the metal strip may be any means such as a pinch roll, a means for sandwiching the metal strip between opposed plates to apply a horizontal force with a hydraulic cylinder, a means for a dancer roll, a means for electromagnetic force, etc. . It is also possible to use a pay-off reel to apply a force in the direction opposite to the carrying direction. If the welding machine has a built-in device that clamps and abuts the preceding and following materials before welding, one or both of these can be used as a test load addition device. it can.

[0016]

According to the present invention, the strength of the welded portion can be quantitatively determined in a short time with inexpensive equipment, and highly reliable welding can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an in-line welding apparatus for metal strips of the present invention.

FIG. 2 is a diagram showing an example of a relationship between stress of a metal material and acoustic radiation intensity.

[Explanation of symbols]

 1 Metal Strip 2 Payoff Reel 3 Input Side Pinch Roll 4 Shearing Machine 5 Welding Machine 6 Output Side Pinch Roll 7a, 7b Acoustic Radiation Sensor 8 Acoustic Radiation Signal Processor 9 Looper

Claims (4)

[Claims] 1. A method for inspecting a welded portion, which is performed subsequent to in-line welding of a metal strip on an inlet side of a continuous processing line, wherein, after the in-line welding, a force in a direction opposite to a strip conveying direction and / or a force in a strip conveying direction. Is added to the strip, and the sound radiation is detected to determine the soundness of the welded portion. An in-line welded portion inspection method for a metal strip. 2. In an in-line welding apparatus on the inlet side of a continuous processing line for metal strips, means for applying a force to the strip in the direction opposite to the strip transport direction on the front side of the welding machine and / or strip transport on the rear side of the welding machine. An in-line welding device for a metal strip, comprising means for applying a force in a direction to the strip, and further comprising acoustic radiation detection means and acoustic radiation signal processing means. 3. The in-line welding device for a metal strip according to claim 2, wherein the means for applying a force to the strip in a direction opposite to the strip conveying direction is a pay-off reel device. 4. A means for applying a force to the strip in a direction opposite to the strip conveying direction on the front side of the welding machine and / or a means for applying a force to the strip on the strip on the rear side of the welding machine is a strip of the welding machine. The in-line welding device for a metal strip according to claim 2, wherein the in-line welding device is a clamping device for positioning.