JPH04291137A - Method and device for inspecting steel-band butt welding portion - Google Patents

Abstract

PURPOSE:To enable a defect at a steel-band butt welding portion to be detected automatically and readily and accurately. CONSTITUTION:A center line of a visual sensor which divides an area 4 into two portions is matched to a welding line 7 at a steel-band butt welding portion and then a difference between an amount of left reflection light and that of right reflection light is detected for the welding line 7 on a surface of two butted steel bands 6 by a visual sensor 1. A camera 2 of the visual sensor 1 is allowed to run along the welding line 7 at an upper portion of the steel bands 6 by a certain height a difference between the amount of left reflection light and that of right reflection light of the area 4 is measured and a voltage signal is output to the welding line 7, and this voltage signal value and a reference value when there are no welding defects which are set previously are compared by an operation mechanism 8, thus enabling a welding defect to be detected according to a difference between the voltage signal value and the reference value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a method and inspection method for inspecting surface defects in a butt welded part of a steel strip that has been welded by a welding machine such as a flash butt welding machine, and whose surface has been processed by a machining machine. It is related to the device.

0002

[Prior Art] In the online process of connecting the ends of butt steel strips to each other using a welding machine such as a flash butt welder (hereinafter referred to as a "welding machine"), a step is formed at the butt weld of the steel strip and near the weld. If there are surface defects such as baldness, scratches, etc., it will hinder the subsequent process, so it is necessary to inspect them.

Conventionally, such inspections involve visually inspecting the surface condition of the steel strip before welding, and then machining the weld bead with a machine (flash trimmer) after butt welding. This was done by re-inspecting the machined surface. If a surface defect is found through inspection and it is determined that the weld is defective, the work is performed in a process of re-welding. Such defects in welds cannot be completely eliminated at present, and therefore there is a demand for the development of a rapid inspection method for discovering defects in welds.

0004

[Problem to be Solved by the Invention] Measuring instruments for inspecting defects in butt welds have existed for a long time, but conventional measuring instruments lack speed in online environments where inspections are time-constrained. Therefore, there was a problem in that it was not possible to quantitatively understand abnormalities in welds.

[0005] For this reason, the above-mentioned visual inspection is still used today. However, since visual inspection relies on the experience of the inspector, it requires skill and individual differences are likely to occur, and requires personnel for inspection, resulting in personnel costs and lost time. There were many problems.

Therefore, an object of the present invention is to provide a steel strip butt weld that can automatically, quickly, and accurately detect defects in a steel strip butt weld welded by a welding machine such as a flash butt welding machine. An object of the present invention is to provide an inspection method and an inspection device.

[0007]

[Means for Solving the Problems] In order to achieve the above object, in the inspection method of the present invention, a camera is used to measure the difference in the amount of light reflected on the left and right sides of the weld line of a steel strip butt weld. and a controller and a ring illuminator for converting the difference in the amount of light reflected by the camera into a voltage change and outputting a voltage signal. A calculation mechanism is provided above the height so as to be movable along the welding line, and a calculation mechanism is provided for comparing the voltage signal value with a preset reference value when there is no welding defect. The present invention is characterized in that a signal value is compared with the reference value, and a welding defect is detected based on the difference between the voltage signal value and the reference value. Further, the present invention is characterized in that the camera and the ring illuminator are attached to a tool rest of a machining machine for machining the surface of a steel strip butt weld. Furthermore, the present invention is characterized in that an alarm mechanism is attached to the calculation mechanism, and the alarm mechanism issues an alarm when a welding defect is detected based on the difference between the voltage signal value and the reference value.

[0008] In order to achieve the above object, the inspection device of the present invention uses a constant height of the steel strip to measure the difference in the amount of light reflected on the left and right sides of the weld line of the steel strip butt weld. It is composed of a camera and a ring illuminator that are provided above so as to be movable along the welding line, and a controller that converts the difference in the amount of light reflection measured by the camera into a voltage change and outputs a voltage signal. The present invention is characterized in that it comprises a visual sensor, and a calculation mechanism for comparing the voltage signal value with a preset reference value when there is no welding defect. Further, the camera and ring illuminator are characterized in that they are attached to a tool rest of a machining machine for machining the surface of the steel strip butt weld. Furthermore, the present invention is characterized in that an alarm mechanism is attached to the calculation mechanism to issue an alarm when a welding defect is detected based on the difference between the voltage signal value and the reference value.

A known visual sensor is used as the visual sensor. Therefore, I will not discuss this in detail, but this visual sensor uses a method of comparing the area integral value of the amount of light on two areas A and B, which are created by dividing the area designated by the pointer into two, and reads two areas with a camera. It has a function of batch processing image information (three-dimensional) including the brightness of each point in a dimension (area) using an analog method. The basic algorithm is to set an image of a normally flowing target object in advance and compare it with the next flowing target object at ultra-high speed.It is capable of recognizing color and shape patterns, and detecting minute color differences. etc. are possible. A ring illuminator is a ring-shaped fluorescent lamp powered by a high-frequency power supply.

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view illustrating the principle of the invention, and FIG. 2 is a front view showing a camera attached to a tool rest. In FIG. 1, 6 is a steel strip, and 7 is a weld line of a butt welded portion of the steel strip. The visual sensor 1 consists of a camera 2 and a controller 3. The camera 2 of the visual sensor 1 and the ring illuminator 9 are installed above the steel strip 6 at a certain height, and the steel strip 6 is moved along the welding line 7 while maintaining this height.
It can run freely from one end of the steel strip to the other in the width direction of the steel strip, and detects the amount of light emitted from the ring illuminator 9 reflected from the area 4 of the weld. The controller 3 has a mechanism that replaces the signal of the amount of reflected light detected by the camera 2 with a voltage change to generate a voltage signal. 8 is a calculation mechanism connected to the controller 3. Computing mechanism 8
has a function of comparing the voltage signal (measured value) output by the visual sensor 1 with a preset reference value when there is no welding defect.

As shown in FIG. 2, the camera 2 of the visual sensor 1 is attached to a tool rest 5 of a machining machine (flash trimmer) provided at the rear of the welding machine. This tool rest 5 has a mechanism that moves in the width direction of the steel strip 6 (in the direction shown by the arrow in FIG. 2) when machining the surface of the butt weld. Camera 2 on this turret 5
By attaching the camera 2 and the ring illuminator 9, the camera 2 and the ring illuminator 9 can be moved above the steel strip 6 at a certain height along the weld line 7, and while machining the welded part with the tool rest 5. Machined surfaces can be inspected. 9 is a light source lamp, and the camera 2 is running.
This is a ring illuminator attached to the tool post 5 so that the area 4 can be always illuminated by following the illuminator.

The camera 2 can be attached not only to the tool rest 5, but also to an appropriately selected one having a mechanism that allows it to move along the width direction of the steel strip 6, or to an external turret. Alternatively, such a moving mechanism may be installed.

Next, the process of inspecting a steel strip butt weld according to the present invention will be explained. FIG. 3 is an explanatory diagram showing the detection area, and FIG. 4 is a flowchart explaining the inspection process of the present invention. As the visual sensor 1, a known sensor is used as described above. The center line of the visual sensor 1 that divides the area 4 into areas A and B is aligned with the welding line 7 using a pointer 10 and positioned. Next, the light source 9 irradiates the left and right areas A and B of the same area with desired light. Next, the camera 2 is moved along the welding line 7 from one end of the plate width to the other end, and the amount of light reflected in the left and right areas A and B moving along the welding line 7 is detected and the difference is detected. Determine.

Specifically, it is determined whether the amounts of light on the left and right sides of areas A and B are symmetrical or asymmetrical with respect to the weld line 7 where the steel strips 6 are butted. That is, if the amount of light is asymmetrical with respect to the welding line, there will be a difference in the width of the cut surface, which will result in a difference in area and will appear as a difference in shape between areas A and B (unevenness on the cut surface). Alternatively, if the color of the cut surface is poor, there will be a difference in brightness, which will appear as a difference in color between areas A and B. In this way, the symmetry of areas A and B is determined from the shape and brightness (color difference).

Since the camera 2 is attached to the tool rest 5, the inspection is performed while the tool rest 5 is machining the steel strip butt weld. That is, the state immediately after machining can be inspected. Then, when a difference occurs in the amount of light reflected in areas A and B, it is output as an analog amount. Further, this output is compared with a preset reference value in the case where there is no welding defect, and if the difference is above a predetermined level, an alarm 11 is issued and this is output to the recorder.

FIG. 5 is a process diagram showing the details of processing in the calculation mechanism of the voltage signal detected by the visual sensor. In the first example of processing, the difference in brightness and shape between areas A and B is detected, and the value (X) obtained by processing the absolute value of this value is compared with the reference value (X0), and if it is above a predetermined level, When the alarm 11 is generated, the alarm 11 is outputted to the recorder 12. Also, in the second example of processing,
The difference in brightness and shape between areas A and B is detected, and the absolute value of this value is processed (X), which is integrated over the entire board width (ΣX).
, divide this value by the plate width (W). Then, compare the value with the reference value, and if it is higher than the predetermined level, alarm 1 is set.
1 and the alarm occurs, the recorder 12
Output to. Although FIG. 5 shows the case where the above two examples are used together, the determination may be made using either of the above two examples.

[0017]

[Example] Next, an example of the present invention will be described. A steel strip butt weld having a finished width (d) of 12 mm after processing by a welding machine was inspected using the inspection apparatus of the present invention shown in FIGS. 1 and 2. The height (a) from steel strip 6 to camera 2 is 61 mm, and the width of area 4 (b) is 8.4 mm.
, the length (c) was 6.3 mm. Tests were then carried out on specimens Nos. 1 to 5 in which defects such as edge stepping, full surface stepping, or center stepping were observed in the steel strip butt welds. The inspection measures the brightness and shape of areas A and B of the same area with weld line 7 as the center line (10000
screen/second), and the brightness difference was output as an analog value ±10 V and recorded by a recorder (pen recorder) 12. Figure 6
is a graph illustrating the results, in which the left and right sides of the graph indicate the width direction of the steel strip 6, and the horizontal axis at the center indicates the reference line of zero voltage. As shown in Fig. 6, each defect present in specimen Nos. 1 to 5 is recorded by a pen recorder, and an alarm is issued in a portion where the output exceeds a certain reference value indicated by an arrow in the figure, thereby indicating a welding defect. is detected.

[0018]

As explained above, according to the present invention, it is possible to automatically, quickly, and accurately detect surface defects in steel strip butt welds whose surfaces have been processed by a machining machine. Moreover, useful effects are brought about.

[Brief explanation of the drawing]

[Fig. 1] A perspective view explaining the principle of this invention

[Figure 2] Front view showing the camera attached to the turret

[Fig. 3] Explanatory diagram showing the area detected by the visual sensor

[Fig. 4] Flowchart explaining the inspection process of this invention

[Fig. 5] Process diagram showing the contents of processing in the calculation mechanism of the voltage signal detected by the visual sensor

[Figure 6] Graph illustrating the results of the example using a pen recorder

[Explanation of symbols]

1 Visual sensor 2 Camera 3 Controller 4 Area 5　Turret post 6 Steel strip 7 Welding line 8 Arithmetic mechanism 9 Ring illuminator 10 Pointer 11 Alarm 12 Recorder

Claims (6)

[Claims] 1. A camera for measuring the difference in the amount of light reflected on the left and right sides of a weld line of a steel strip butt weld, and replacing the difference in the amount of reflected light measured by the camera with a voltage change. A controller for outputting a voltage signal and a ring illuminator as a light source for illuminating the welding surface. The camera and the ring illuminator of the visual sensor are movable along the welding line at a certain height above the steel strip. Further, an arithmetic mechanism is provided for comparing the voltage signal value and a preset reference value when there is no welding defect, and the arithmetic mechanism compares the voltage signal value and the reference value to calculate the voltage. A method for inspecting a butt weld of steel strips, characterized in that weld defects are detected based on the difference between a signal value and the reference value. 2. The method for inspecting a steel strip butt weld according to claim 1, wherein the camera is attached to a tool rest of a machining machine for machining the surface of the steel strip butt weld. 3. Attaching an alarm mechanism to the arithmetic mechanism,
The method for inspecting a steel strip butt weld according to claim 1, wherein the alarm mechanism issues an alarm when a welding defect is detected based on the difference between the voltage signal value and the reference value. 4. A welding line provided at a certain height above the steel strip so as to be movable along the welding line for measuring the difference in the amount of light reflected on the left and right sides of the welding line of the steel strip butt weld. A visual sensor including a camera, a controller for converting the difference in the amount of light reflection measured by the camera into a voltage change and outputting a voltage signal, a ring illuminator that illuminates the welding surface, and the voltage signal value. 1. An inspection device for a butt weld of a steel strip, comprising a calculation mechanism for comparing the value with a preset reference value in the case of no weld defects. 5. The inspection device for a steel strip butt weld according to claim 4, wherein the camera is attached to a tool rest of a machining machine for machining the surface of the steel strip butt weld. 6. The steel strip butt weld according to claim 4, wherein the calculation mechanism is equipped with an alarm mechanism for issuing an alarm when a welding defect is detected based on the difference between the voltage signal value and the reference value. inspection equipment.