JPH06307999A - Method and equipment for inspecting welded part of steel band - Google Patents

Abstract

PURPOSE:To decide the pass/fail of welding quickly without relying on the feeling of expert by running a press roller on a weld line immediately after welding while pressing the roller downward and then deciding the pass/fail of welding based on the crack at the welded part. CONSTITUTION:After positioning the rear end of a preceding steel band and the front end of a following steel band, welding disc electrodes 6, 6' are shifted while rotating from one end toward the other end in the breadthwise direction of the band steel along a weld line thus welding the preceding and following steel bands. A press roll 10 is shifted while rotating from the rear of the electrodes 6, 6' while spacing apart therefrom by a predetermined distance thus pressing the weld line immediately after welding. The press roller 10 is coupled with a press cylinder 11 which is coupled with a hydraulic pressure source through a hydraulic solenoid valve 12. Since the required pressure varies depending on the thickness or material of the steel band, a pressure conversion valve 13 and a pressure gauge 14 are provided for the hydraulic circuit. When a crack due to press is detected visually or by means of a camera or photoelectric device, the steel bands can be welded immediately under clamped state thus minimizing the line stop time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a welded portion of a steel strip in a continuous processing line for a steel strip and an apparatus therefor.

[0002]

2. Description of the Related Art In a processing line such as a processing line for rolling a steel strip, a surface treatment line for plating, a heat treatment line for annealing, etc., the trailing end of the preceding steel strip and the leading end of the following steel strip on the line entry side. The steel strips passing through the inside of the line are continuously processed by connecting and by welding. As a welding method, a seam welding in which these end portions are overlapped with each other or a butt welding in which the end portions are abutted to each other is adopted depending on the material and the plate thickness.

By the way, if these weldings are not sufficiently performed, an accident occurs in which a joint portion is broken in a process line, for example, in an annealing furnace. When a plate rupture occurs, not only must the operation be interrupted,
It is necessary to take measures such as removing the broken steel strip and newly passing it through the line.Depending on the line, the temperature of the furnace must be lowered in order to carry out these works. Had to lose with line down time.

Therefore, as described in, for example, Japanese Patent Laid-Open No. 3-207584, in the case of resistance welding, the welding current state, voltage value, surface temperature of the steel strip, etc. are measured to diagnose the welding state. Welding diagnostic system that does. In this welding diagnosis system, reference values for the plate thickness, material, etc. to be welded are set, and the allowable range is set based on this to determine the presence or absence of abnormalities, but in the case of welding methods, such as butt welding, Even if there is no difference in these measured values, the frequency of fractures is high, especially when the steel plate thickness is thin,
For example, it was almost impossible to judge the welding state from the measurement of temperature and current value for those of 0.2 mm or less. For this reason, hammering tests such as hitting the welded part of the steel strip with a hammer on the exit side of the welding equipment to judge the quality of the welding have been conducted, but since it is necessary to make a judgment based on many years of experience, an expert Is difficult and inefficient,
Improvement was desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above problems, and an inspection method for quickly determining the quality of welding without relying on the experience of an experienced person and minimizing the line stop time. And to realize the device.

[0006]

A method for inspecting a welded part of a steel strip according to the present invention is a welding device for a steel strip for connecting a trailing end of a preceding steel strip and a leading end of a trailing steel strip in a continuous strip processing line. In the above, it is characterized in that the pressure roller is driven downward on the welding line immediately after the welding is completed, and the quality of the welding is judged from the occurrence of cracks in the welded portion.

The steel strip welded portion inspection apparatus of the present invention is
In a steel strip welding device that connects the trailing end of a preceding steel strip and the leading end of a trailing steel strip in a continuous processing line for steel strips, it is attached to a pressurizing cylinder that generates downward pressure, and the welded part is moved downward. It is characterized in that it is provided with a pressure roller capable of traveling on the welding line while being pushed.

[0008]

[Operation] In the present invention, immediately after welding, the pressure roller is run along the joining line, and bending deformation is given to the welded portion to judge the quality of the welding. In the case of a welding defect that causes welding breakage, cracking will occur at this point, so it can be easily and surely found, and by promptly restarting welding, it is possible to prevent welding breakage in the line in advance. , There is almost no delay time for that.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention is shown in FIGS. Figure 1
2 is a perspective view showing the structure of the welded portion inspection apparatus for a steel strip of this embodiment, and FIG. 2 is a sectional view taken along the line AA of FIG. 1 is a leading steel strip, 2 is a trailing steel strip, 3 and 3'is an output side clamp, 4 and 4'is an input side clamp, 5 is a welding line, 6 and 6'is a welding electrode, 10 is a pressure roller, 11 is a pressurizing cylinder, 12 is a hydraulic electromagnetic switching valve, 13
Is a pressure conversion valve, and 14 is a pressure gauge.

This welding portion inspection device constitutes a part of a welding machine installed on the inlet side of a continuous processing line for steel strips, and the rear end portion of the preceding steel strip 1 fed into the line is exposed. It is captured by the side clamps 3 and 3 ', and when the leading end of the succeeding trailing steel strip 2 arrives and is captured by the entry side clamps 4 and 4',
Both ends are butted or overlapped. Although a shearing machine for shearing both ends is usually provided in parallel for the purpose of joining the abutting surfaces together, the illustration thereof is omitted here.

When the abutting surface or the overlapping surface is positioned at the welding position in the center of both the inlet side and outlet side clamps, a circle is drawn along the welding line 5 from one end to the other end in the width direction of the steel strip. The plate-shaped upper and lower welding electrodes 6 and 6 ′ rotate and move in the directions of arrows, for example, to perform welding, and connect the rear end portion of the preceding steel strip 1 and the leading end portion of the following steel strip 2. The process up to this point is exactly the same as that of the seam welder used conventionally.

In this embodiment, as shown in FIG.
While the pressure roller 10 rotates and moves from a certain distance behind the welding electrodes 6 and 6 ', the welding line 5 immediately after the completion of welding is pressed downward. The pressure roller 10 is connected to a pressure cylinder 11 that generates a downward pressure from a hydraulic power source (not shown) via a hydraulic electromagnetic switching valve 12. Since the required pressure depends on the thickness and material of the steel strip at that time, the pressure conversion valve 13 and pressure gauge 14 are installed in the hydraulic circuit leading to the pressurizing cylinder.
Is also equipped.

The pressure roller 10 has a diameter of 250 mm and a thickness of 12
When a steel plate with a thickness of 0.2 mm is used, it is appropriate that the pressure of the pressure cylinder 11 is about 10 kgf / cm ^{2 when} welding steel plates with a thickness of 0.2 mm, and cracks did not occur in normal welding, but the pressure was 30 kgf / cm ^2. It was found that when the area was about cm ^2, cracks were generated from portions other than the welded portion, which was inappropriate. The appropriate pressure depends not only on the plate thickness and material of the steel strip, but also on the dimensions of the pressure cylinder 11 and the pressure roller 10, and so on.

The pressure roller 10 may be moved in the plate width direction by its own moving means, but it is directly connected to the welding electrodes 6 and 6'which move in the same manner in advance. The easiest and most desirable. In this case, not only can the rails and drive device for movement be used as they are,
The elapsed time from welding to pressing becomes constant depending on the distance of the pressure roller 10 from the electrode. It should be noted that it is inconvenient if the pressure roller 10 and the electrode are too close to each other, for example, if the pressure is applied before the weld metal has completely solidified, it may be inconvenient if the steel strip is thin. If you consider the distance you get, there is not much problem.

By pressing the welded portion from above and bending it into a groove shape in this way, cracking occurs only in the case of defective welding, and this is easily found by visual inspection or by a camera, a photoelectric device, or the like. Re-welding can be performed immediately in the clamped state to prevent weld breakage in the line.

[0016]

According to the present invention, instead of the conventional hammering test, the welded portion can be bent under a constant condition, a welding defect can be surely found, and re-welding can be immediately performed. It is possible to avoid welding breakage in the line and improve the operation efficiency of the line.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

 1 Leading steel strip 2 Trailing steel strip 3, 3'Outlet side clamp 4, 4'Inlet side clamp 5 Welding line 6, 6'Welding electrode 10 Pressure roller 11 Pressure cylinder 12 Hydraulic solenoid switching valve 13 Pressure conversion valve 14 Pressure gauge

Claims (2)

[Claims] 1. A welding device for a steel strip for connecting a trailing end of a preceding steel strip (1) and a leading end of a trailing steel strip (2) in a continuous processing line for steel strips, wherein a welding line (5) immediately after welding is completed. ) A method for inspecting a welded part of a steel strip, characterized in that it is run while pressing a pressure roller (10) downward, and the quality of welding is judged from the occurrence of cracks in the welded part. 2. A welding device for a steel strip connecting a trailing end of a preceding steel strip (1) and a leading end of a trailing steel strip (2) in a continuous processing line for steel strips. A welding inspection device for a steel strip, comprising a pressure roller (10) which is attached to a pressure cylinder (11) and can travel on a welding line (5) while pushing the welding portion downward.