JPS6069503A - Measuring method of shape of steel plate end part - Google Patents

Abstract

PURPOSE:To find a scanning position by deciding that the intensity of reflected light and the phase difference of the reflected light from a laser modulating signal are within specific ranges, and also measure the two-dimensional shape of a steel plate end part by using information, etc., obtained from a movement extent signal. CONSTITUTION:The output light of a laser 4 scans breadthwise on the surface of a steel plate 1 as small spot light 8. Part of irregularly reflected laser light is converged by a parabolic mirror 6 again and guided out as a photodetected light beam 10 by a mirror 9. The photodetected light beam 10 is incident on a photoelectric converting element 13 and amplified by a high frequency amplifier 14. The amplified output signal is led to a level decision signal 18 to obtain its phase difference from the output signal of a high frequency oscillator 2 and a decision device 19 generates the presence/absence signal of a steel plate eventually by the output of a phase decision device 16. A scanning position computing element 21 performs arithmetic on the basis of the steel plate presence/ absence signal and the angle detection signal 20 of a rotary mirror 5 and a shape arithmetic circuit 23 obtain the shape measured value 24 of the final head and tail of the steel plate 1 from the output of a detector 22 for the movement extent of a roll 25 for moving the steel plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for optically measuring the two-dimensional shape in the width direction of the end portion of a steel plate including the leading end and tail end.

In the production of steel plates, for example, the tip and tail ends of the steel plate are generally chevron-shaped or have a concave shape in the center called a fillan tail, but when such a steel plate is further rolled or the final In order to make it into a product, it is necessary to cut out this abnormally shaped part. However, if this cutting is made larger than necessary, the yield of the steel plate will decrease, so the amount of cutting must be minimized from an economic standpoint. For this reason, it is necessary to accurately measure the shape of the tip and tail end to determine the optimal cutting point, and various shape measurement methods have been proposed for this purpose. For example, there are methods such as automatically measuring the shape by taking pictures with a TV camera, etc., and methods that combine a one-dimensional linear array camera and a steel plate movement distance signal. These methods are based on the method of detecting self-luminescence of the steel plate or the method of illuminating the steel plate with a light and detecting the reflected light, but stable detection is difficult, and measurement of extremely long and unusual shapes is difficult. Alternatively, there were problems such as large errors occurring due to vertical movement of the steel plate.

Therefore, the present invention solves these problems and makes it possible to measure various abnormal shapes stably and with high precision.According to the present invention, it is possible to measure various abnormal shapes with high precision. It is possible to measure steel plates over a wide range of areas, and it is possible to provide an extremely useful shape measurement method in the steel plate industry. Scanning the moving steel plate in the width direction, converting the reflected light from the surface of the steel plate into an electrical signal using a light receiving device, and checking that the intensity of the reflected light and the phase difference of the reflected light with respect to the laser modulation signal are within a predetermined range. In addition to determining the presence or absence of partial defects in the width direction of the steel plate, the scanning position of the laser beam is determined by the beam position calculation device from the angle of the rotating surface mirror, and the movement of the steel plate is determined by the movement amount detector. This is achieved by a method for measuring the shape of the edge of a steel plate in which the two-dimensional shape of the edge of the steel plate is measured using information such as a quantity signal.

The invention will now be described in detail with reference to an embodiment shown in the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an example of an apparatus for implementing the method of the present invention, in which 1 is a steel plate to be measured, which is moving on a roll 25. The output of the high frequency oscillator 2 is connected to a laser modulator 3, which modulates the intensity of the output light of the laser 4 into a high frequency sine wave.

A suitable semiconductor laser for the laser 4 is H
An e-Ne laser or other lasers can also be used, and the output light of this laser 4 is scanned in a fan shape by a rotating mirror 5, and further converted into parallel scanning by a parabolic mirror 6, so that it scans over the surface of the steel plate 1. It becomes a small spot light 8 and scans in the width direction. A part of the laser beam that is diffusely reflected on the surface of the steel plate 1 is again focused by the parabolic mirror 6 and returns along the same optical axis as the laser beam through the rotating mirror 5, but there is a hole 9a in the center. Only the reflected light is taken out as a received light beam 10 by the mirror 9 provided with the light beam. Since the mirror 9 is provided only to separate the laser light source and the reflected received light beam 10, it goes without saying that other means such as a half mirror can be used. After the received light beam 10 removes disturbance light through an interference filter 11, it enters a light receiving device (photoelectric conversion element) 13 through an imaging lens 12, and the output signal of this light receiving device 13 is amplified by a high frequency amplifier 14. The intensity of the reflected light of the amplified output signal is detected by the amplitude detector 17, and the level determiner 18 determines that a steel plate is present when the reflected light intensity is above a certain value, and determines that there is no steel plate in the following cases. do. It seems that the presence or absence of a steel plate can be reliably detected using only the intensity of this reflected light, but in actual steel plates, the intensity of the reflected light varies greatly depending on the location, and even when there is no steel plate, reflection from other objects can occur. In many cases, it is as strong as a steel plate, making stable detection difficult.

Therefore, in the method of the present invention, the high frequency amplifier 14
The phase difference between the output signal of
In particular, it is determined that there is a steel plate.

Based on the output signals of both the level determiner 18 and the phase determiner 16, a steel plate presence/absence signal is finally generated by a steel plate presence/absence judge 19. Based on this steel plate presence/absence signal and the angle detection signal 20 of the single rotating mirror 5, the scanning position calculator 21 calculates the position signal in the width direction of the laser beam spot on the steel plate 1 and the amount of movement of the steel plate moving roll 25. vessel(
A final shape measurement value U of the tip and tail end of the steel plate l is obtained by the shape calculation circuit 23 from the steel plate movement amount signal which is the output of the rotation angle detector) 22. This shape calculation method is used as a second method.
To explain with a figure, the figure (A) shows the case where the tip is rounded, and in this case, the position where W is a certain width narrower than the plate width W and the length to the tip can be seen. In addition, the same figure (b) shows the case where the center part of the tip is concave, and as in (a) above, the position where the width becomes constant W' and the length at the tip 1,
In addition, the position of the central concave valley and the length L2 to the tip can be determined. In this way, the shapes of the tip and tail ends of the moving steel plate 1 are measured.

Next, detection of the vertical position of the steel plate 1 will be explained.

Since laser light is modulated with high frequency, the high frequency modulated signal has a phase delay depending on the optical path length until the reflected light is received.
Assume that the distance and the delay in the electronic circuit are adjusted so that the phase difference is exactly 90 at the position. At this time, the output voltage of the phase difference detector is exactly O as shown in FIG.

Change. If we now assume that λ=6 m (50 MHz), it will be θ-90 at 2275 m, and it can be understood that sufficient detection is possible. If the limit of θ is appropriately selected, it becomes possible to determine that it is a steel plate cloth only when the reflected positional force is within the range of avoidance at any t. In FIG. 3, a indicates a background object.

Furthermore, if the position of the rotary mirror 5 is placed inside the focal point of the parabolic mirror 6 for fan-shaped scanning, there is a problem that errors occur due to the vertical movement of the steel plate 1, but the parabolic mirror The width of steel plate 6 can be made smaller than that of steel plate 1. Furthermore, it is also possible to omit the parabolic mirror 6 and scan the laser beam in a fan shape using only the rotating mirror 5 or the vibrating mirror. In the case of the fan-shaped scanning method shown in these two examples, errors occur in the edge position detection accuracy in the width direction of the steel plate due to the vertical movement of the steel plate, but this may not be a problem if the displacement of the steel plate is small.

Further, it is also possible to correct the error in the edge position detection accuracy using the detection signal of the vertical displacement.

As described above, the present invention uses a high-frequency modulated laser as a light source, so it is possible to stably and accurately measure the two-dimensional shape at the edge of a steel plate even when the steel plate is red-hot and there is a lot of disturbance light. This is a measurement method that is extremely useful in improving the cutting accuracy of the edges of steel sheets and greatly reducing losses in steel sheet manufacturing, and improving its economic efficiency and quality of steel sheets. can be provided.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of an apparatus for carrying out the method of the present invention, Figures 2 (a) and (b) are explanatory diagrams showing a method for calculating the shape of the edge of a steel plate, and Figure 3 is a diagram showing a method for calculating the shape of the edge of a steel plate. FIG. 4 is a characteristic diagram of the phase difference detector. Patent applicant Hidehiko Yamada Figure 3 Figure 4

Claims (1)

[Claims] A high-frequency modulated laser beam is scanned in the width direction of a moving steel plate by a rotating mirror and a parabolic mirror, and the reflected light from the surface of the steel plate is converted into an electrical signal by a light receiving device, and the reflected light is reflected. A section in the width direction of the steel plate by determining that the intensity of the light and the phase difference of the reflected light with respect to the laser modulation signal are within a predetermined range. In addition to detecting the presence or absence of formal defects, the scanning position of the laser beam is determined from the angle of the rotating surface mirror by the beam position calculating device, and the edge of the steel plate is determined based on information from the movement amount signal from the steel plate movement amount detector. A method for measuring the shape of an end portion of a steel plate, the method comprising measuring the two-dimensional shape of the end portion of a steel plate.