JPH04353710A - Method and apparatus for welding metal strip - Google Patents

Abstract

PURPOSE:To perform welding work by accurately identifying a welding position, measuring the height of a rear bead, and judging the quality of laser Uranami welding. CONSTITUTION:In a running truck 4, a C-shaped frame 41 having two arms extending upward and downward putting a metal strip 1 between them is provided. A welding torch 2 is attached to the tip of the upper arm so as to face downward to the metal strip. A laser distance meter 3 is attached to the tip of the lower arm so as to face upward to the metal strip at a diatsnce which is slightly closer than the welding torch described above. Running rails 5 are provided at a right angle with a line so as to move the truck. The apparatus is constituted of these parts.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method and apparatus for laser butt welding performed in a continuous processing line for metal strips, particularly thin metal strips.

0002

[Prior Art] In continuous processing lines for metal strips, butt welding is carried out between the rear end of the preceding metal strip and the tip of the following metal strip, but in recent years, especially in continuous processing lines for thin materials, laser Welding is increasingly being used. During laser welding, the opposing ends of the metal strips on both sides are cut at exactly the same angle, for example, at right angles, to the line direction, butted together with a predetermined gap, and welded along this butted line (hereinafter referred to as the welding line). The torch is moved and a laser beam is irradiated to melt the mating surfaces and perform welding.

[0003] As methods for determining the quality of welding, there are methods such as determination based on the welding sound during welding, monitoring of abnormal discharge using an arc sensor, and a method of monitoring and controlling a laser oscillator as disclosed in Japanese Patent Laid-Open No. 2-52477. Another method is to take a sample of the weld and perform an Erichsen test or a bend test, but monitoring the welding power source is a somewhat indirect method of determining the welding condition itself, and the method of taking a sample is a direct method. However, it cannot be used for online judgment. However, according to the experimental results shown in FIG. 3 conducted by the present inventors, the height of the bead on the back surface is 33% relative to the mother plate thickness.
If it is in the range of ~12%, the bend test results are good, so it was found that it is practical to judge the quality of welding by monitoring the back bead. In order to obtain a sound back bead shape, it is good to use a backing device as described in Japanese Utility Model Publication No. 62-27346, but it takes time to attach and remove the backing device, and the structure of the welding device is complicated. Because of these problems, so-called uranami welding without backing tends to be preferred. Japanese Patent Application Laid-Open No. 61-212493 proposes inspecting the weld by measuring the height of the back wave of the weld immediately after welding. 5 and 6 show the technique disclosed in Japanese Unexamined Patent Publication No. 61-212493. 1 or 11 and 12 are metal strips, 2' is a welding laser, 3 is a non-contact displacement meter, and 5 is a running rail, and the non-contact displacement meter tracks the laser-welded weld bead 13. It attempts to continuously measure distance using triangulation. 6 is a clamp that fixes the metal strip during welding work.

0004

[Problem to be solved by the invention] By the way, JP-A-61
The method disclosed in Publication No. 212493 is valid in principle, but if it is applied to an actual line with thin materials, wide widths, and high speed operation conditions, it is difficult to accurately capture the position of a weld bead, for example, and to use a non-contact displacement method. It is difficult to keep track of the total. It is an object of the present invention to solve these problems and provide a practical Uranami measuring device.

[0005]

[Means for Solving the Problems] The present invention provides a running device with a C-shaped frame having two arms extending upwardly and downwardly across the metal strip in laser butt welding in a continuous processing line of metal strips. A welding torch is attached to the upper arm of the trolley, a non-contact displacement meter is attached to the lower arm, and the height of the welded back bead immediately after welding is measured by running this traveling trolley along the welding line. Features.

[0006]

[Function] According to the present invention, the laser distance meter and the welding torch are fixed to the same trolley and move together, so that
Accurately capturing the bead position and continuously measuring the distance can be carried out very easily.

[0007]

Embodiment An embodiment of the present invention will be explained in detail with reference to FIGS. 1 and 2. 1 is a metal strip that is the material to be welded, and if this metal strip is conveyed in the direction of the arrow in FIG. be. On the other hand, the trolley 4, which runs on a traveling device consisting of a rail 5 laid parallel to the welding line, for example perpendicular to the line direction, and a traveling means (not shown), has two arms extending upward and downward across the metal strip. A C-shaped frame 41 is provided, and a welding torch 2 is attached to the tip of the upper arm of the frame 41 facing downward toward the metal strip, and a welding torch 2 is attached to the tip of the lower arm slightly forward of the upper welding torch 2. A non-contact displacement meter, in this embodiment a laser distance meter 3, is mounted facing upward toward the metal strip. As shown in FIG. 1, three laser range finders 3, 31, 32, and 33, are arranged in parallel at right angles to the traveling direction of the truck, corresponding to the welded portion and the base plate portions on both sides.

For welding the strip in the width direction, the carriage 4 is welded as shown in FIG.
This is done by moving the welding torch in the direction of the arrow, that is, from outside the line to inside the line, but since the laser distance meter is also fixed to the same trolley, the central laser distance meter 32 runs on the same straight line as the welding torch 2. The height of the back bead can be measured as the distance h2 in FIG. 1 by accurately tracking the welding torch 2. The laser range finders 31 and 33 on both sides measure the height of the normal base plate near the welded part as distances h1 and h3. Here, the bead excess thickness is (((h1+h3)/2-h2)/base plate thickness)
Since it can be expressed as ×100 (%), h1,
Calculate this from h2 and h3 and set the standard range, for example 3 to 1.
The welding conditions, that is, the amount of heat input, the amount of weld metal supplied, the welding speed, etc., can be controlled so that the ratio is 2%, and this can also be reflected in the operating conditions of the rolling operation, which is the next step.

In addition, in FIG. 1, a laser distance meter 3' is also shown in front of the welding torch 2 on the upper part of the frame 41 of the truck 4, but this is for the purpose of observing the surface bead as well.
Although the judgment accuracy is further improved, it does not need to be installed if it is not necessary.

0010

[Effects of the Invention] According to the present invention, it has become possible to accurately and quantitatively evaluate the external appearance of welded parts, which reduces troubles caused by poor welding and improves quality. It has excellent effects such as reducing

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the configuration of the present invention, viewed from a direction perpendicular to a line.

FIG. 2 is a cross-sectional view of the configuration of the present invention, viewed from the line advancing direction.

FIG. 3 is a graph showing the relationship between the back bead reinforcement rate and the bend test according to the present invention.

FIG. 4 is a graph showing an example of measurement of the back bead reinforcement rate according to the present invention.

FIG. 5 is a cross-sectional view showing the configuration of a conventional technique as seen from a direction perpendicular to the line.

FIG. 6 is a cross-sectional view of the configuration of a conventional technique viewed from the line advancing direction.

[Explanation of symbols]

1, 11, 12 Metal strip 13 Welding section 2 Welding torch 3, 31, 32, 33 Laser distance meter 4
Trolley 5 rail

Claims (4)

[Claims] Claim 1: In laser butt welding in a continuous processing line for metal strips, a C having two arms extending upward and downward across the metal strip.
A welding torch is attached to the tip of the upper arm of the traveling trolley equipped with a shaped frame, and a non-contact displacement meter is attached to the lower arm.
By running this traveling trolley along the welding line,
A method for inspecting a welded part of a metal strip, characterized by measuring the height of a welded back bead immediately after welding. [Claim 2] A total of three non-contact displacement meters are installed in parallel at right angles to the welding line, corresponding to the welded part and the base plate position on both sides, and the height of the welding uranami bead and the base plate height are measured. Measure at the same time,
2. The method for welding metal strips according to claim 1, wherein the overlay ratio of the uranami bead is calculated as the difference. 3. In laser butt welding in a continuous processing line for metal strips, a C having two arms extending upward and downward across the metal strip.
a running trolley with a shaped frame; a welding torch mounted on the upper arm of the trolley pointing downwards towards the metal strip;
The welded part of the metal strip consists of a non-contact displacement meter attached to this lower arm at a distance slightly in front of the welding torch and facing upward toward the metal strip, and a traveling device that runs the trolley along the welding line. Inspection equipment. 4. The metal strip welding apparatus according to claim 3, wherein a total of three non-contact displacement meters are arranged in parallel at right angles to the welding line, corresponding to the welded portion and the base plate portions on both sides.