JPS6174728A - Welding zone detecting method of metal strip - Google Patents

Abstract

PURPOSE:To elevate a detecting accuracy by coating a fluorescent paint, etc. on the side face nearby the strip welding part under welding then, by detecting with a fluorescent detector, etc. during the strip passing. CONSTITUTION:A fluorescent paint 8 or magnetic paint is coated by a paint roll on the side face 6 close to a welding part 4 during butt welding of a metal strip 2. A fluorescent detector 12 or magnetic detector is arranged in opposition at the position necessary for the detection of the welding zone 4 on a processing line. In case of the fluorescent detector 12 the position of the optical axis is slid for arrangement in order to prevent an interference. With said method the fluorescent paint 8 or magnetic paint can be detected with good accuracy without using a hole for detection nor having any effect in annealing during the passing of the strip 2. The detecting accuracy at the elusion part is therefore elevated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting a weld in a metal strip, and particularly relates to a method for detecting a weld in a continuous metal strip processing line without the need for a detection hole. used for detection.

[Conventional technology]

Generally, in various metal strip processing lines, metal strips are processed continuously, so butt welding is performed by flash butt welding or the like at the input side of the line, and the welds are easily cleaned. The connected metal strips were subjected to treatments such as pickling and rolling, and the welded parts were cut and removed at the line exit or in the next process. This is because the welded part is hardened compared to the base metal, and there are many blowholes, etc., so it cannot be used as a product.

On the other hand, in such a processing line, processing and manufacturing conditions are generally set in loft units of the metal strip, and therefore it is necessary to detect welds within the processing line and grasp the loft units. That is, it was necessary to detect the weld in order to change processing conditions before and after the weld and operate various devices.

Conventionally, in order to detect a weld, a detection hole was drilled in a metal strip, and the hole was detected using a light projector and light receiving panel installed on the line to determine the weld.

However, with recent advances in bath welding technology, the quality of the welded part has improved, and it has become possible to roll it and use it as a product, eliminating the need for cutting and removing it. It is not preferable from the viewpoint of yield.

As a method for detecting welds that does not require a detection hole, when estimating the position of the weld by calculating the passing distance of a metal strip using a pulse oscillator, etc., it is possible to correct errors caused by strip slippage, catenary, etc. To do this, there is a method of detecting the weld using a hardness meter, a full flow sensor, etc., using the difference in hardness between the weld and the base metal, but there is a problem that it cannot be detected if the weld is heat treated.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above, and to provide a method for detecting welds that does not require a detection hole and has good accuracy.

[Means and operations for solving the problems] The gist of the present invention is as follows.

That is, in a method for detecting a welded part in which metal strips are butt-welded to connect a metal slip passing through a processing line, the longitudinal side surface of the metal strip in the vicinity of the welded part during the welding. Detecting a welded part of a metal strip, comprising the steps of: applying paint to the side surface of the metal strip IJ tube; and detecting the paint applied to the side surface of the metal strip IJ tube with a detector while passing through the metal strip. It's a method.

The details of the present invention will be explained with reference to examples using the illustrated fluorescent paint. First, as shown in FIG. 1, during butt welding of the metal strip 2, a fluorescent paint 8 is applied to the longitudinal side surface 6 in the vicinity of the welded portion 4 using a paint roll 10. The paint roll 10 contains a fluorescent paint 8 and is applied by being pressed onto the side surface 6 of the metal strip when necessary using a nolinder or the like.

The fluorescent paint 8 is applied to the side surface 6 because if it is applied to the surface of the metal strip 2, it may be transferred to other parts by the rolls in the device.

Next, fluorescence detection M12 is placed on both sides of the metal slab 1-IJ tube 2 at a position in the processing line where detection of the welded portion 4 is required, as shown in FIG. The fluorescence detectors 12 on both sides are installed with their respective optical axes shifted to prevent interference, as shown in the figure.

By detecting the fluorescent paint 8 applied to both sides with the fluorescence detection @12 on both sides, the welded part 4 can be grasped and the welded part 4 can be detected with high precision.

Next, an example using magnetic paint will be explained with reference to FIG. Magnetic paint 14 is applied to the longitudinal sides 6 in the vicinity of the weld 4 during butt welding of the metal strip 2, as in FIG.

In this case as well, as shown in FIG. 3, the magnetic paint 14 is detected by the magnetic detectors 16 placed on both sides of the metal strip 2 at the location where the weld 4 needs to be detected, and the position of the weld 4 is determined. can do. The magnetic detectors 16 placed on both sides can be placed on a straight line facing each other because they do not interfere with each other like the fluorescence detection N12.

The present invention is a direct detection of paint, and the detection accuracy is improved by making the point detected by the detectors on both sides the welded part.
Furthermore, welds can be detected without being affected by annealing.

〔Effect of the invention〕

According to the present invention, paint is applied to the longitudinal side surface near the welded part during welding of the metal strip, and the paint is detected by a detector while the metal strip is threaded, and annealing is performed without using a detection hole. This made it possible to detect welds with high accuracy without being affected by the effects of heat, resulting in stable line operations and improved product yield.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the application of fluorescent paint to the side surface of the metal strip IJ according to the present invention, FIG. 2 is a perspective view showing the detection of the fluorescent paint applied to the side surface of the metal strip according to the present invention, and FIG. FIG. 2 is a perspective view showing detection of magnetic paint applied to the side surface of the metal IJ tube in the present invention. 2 Metal strip 4...Welded part 6...Side surface
8... Fluorescent paint 12... Fluorescence detector
14-...Magnetic paint 16...Magnetic detector

Claims (3)

[Claims] (1) In a method for detecting a welded part where metal strips are butt-welded to connect metal strips passing through a processing line, a paint is applied to the longitudinal side surface of the metal strip near the welded part during the welding. 1. A method for detecting a welded part of a metal strip, comprising the steps of: detecting the paint applied to the side surface of the metal strip with a detector during passing through the metal strip. (2) The method for detecting a welded part of a metal strip according to claim 1, wherein the paint is a fluorescent paint and the detector is a fluorescence detector. (3) The method for detecting a metal strip detection part according to claim 1, wherein the paint is a magnetic paint and the detector is a magnetic detector.