JPH01320455A - Device for detecting cracked edge and hole of belt-like material - Google Patents

Abstract

PURPOSE:To highly accurately detect a cracked edge or hole of a belt-like material on a high-speed rolling line under adverse circumference by respectively covering a light projecting and receiving sections with glass plates and washing the glass plates with a washing liquid supplying device or a washing liquid jetting device. CONSTITUTION:Two sets of light projecting sections 1 and light receiving sections 2 are provided on both edges of a belt-like material 3. A glass plate 6 is provided in an inclined state so as to cover the LED 5 of the section 1. A washing liquid 7 is supplied to the upper surface of the glass plate 6 from a washing liquid supplying device 8 and the rolling mill lubricant adhering to the surface of the glass plate 6 is washed down to a drainage groove 9. Another glass plate 14 is horizontally provided closely to the lower surface of the condenser lens 1 of the light receiving section 2. A washing liquid 18 supplied from a washing liquid tank 16 by means of a washing liquid supplying pump 15 is jetted on the lower surface of the glass plate 14 from a nozzle 17. This washing is performed when roll arrangement is changed and the washing liquid 18 washing down the glass plate 14 is contained in a receiving saucer 21. In addition, compressed air 20 is blown from a nozzle 19. Thus a decline in fault detecting ability of the title detector caused by the rolling mill lubricant can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection device for detecting edge cracks and holes in a strip.

[Prior art] Defects such as edge cracks and holes that occur in cold-rolled steel sheets are caused by non-metallic inclusions during the previous slab casting process, scale encroachment during hot rolling, or rolling at an inappropriate temperature range. Various measures have been taken to eliminate these defects. However, it is difficult to completely eliminate these defects, and sometimes the presence of these defects causes strip breakage in a continuous annealing line of cold-rolled steel sheets. In order to prevent such troubles, it is necessary to discover these defects in the cold rolling line, which is a pre-process of the continuous annealing line, and take measures such as removing the defective parts or stopping charging. As an example of such a defect detection device, there is an optical defect detection device in which a light projector is placed on the lower side of the cold-rolled steel sheet, and a light receiver in which photodiodes are arranged in a line in the width direction of the cold rolled steel sheet is placed on the upper side. The principle of defect detection using this device is as follows. In other words, the light emitted from the projector is blocked by the steel plate, but
Light passing through areas with edge cracks or holes enters the light receiver after passing through those areas. Of the photodiodes in the light receiver, those that receive light are at a high level, that is, in an input state, and those that do not receive light are at a low level, that is, in an unattended state. Therefore, by reading out the signal level of the photodiode in the width direction, it is possible to ascertain the presence or absence of a defect, its size, and its position.

There is also a method of using a -axis or two-axis image sensor, but the principle is similar to the optical type described above.

[Problems to be Solved by the Invention] The prior art as described above has the following problems.

(1) Detection responsiveness is low.

With the conventional technology, the line speed is 550m/min and the depth is 9.9cm.
, the detection limit is the detection of a defect with a width of 1■, and the line speed is 1
, 800 m/min cold rolling line.

(2) Low environmental resistance.

When applying defect detection equipment to cold rolling lines, it is important to be able to deal with the adverse environment caused by rolling oil. That is, rolling oil becomes semi-solid when cooled and is likely to stick to the detection device, and also floats in the air with water vapor, blocking light from the projector. Furthermore, coupled with the problem of high temperature and high humidity in the place where they are applied, there are no examples of applying optical sensors to cold rolling lines, and no technology has been established that can cope with such adverse environments.

(3) The equipment is expensive.

Whether it is an optical type or one that uses an image sensor, the detection device is very expensive.

This invention solves the problems of the prior art as described above, and provides a low-cost detection device that can accurately detect defects such as edge cracks and holes in cold-rolled steel sheets in adverse environments and on high-speed rolling lines. It is intended to.

[Means for Solving the Problems] An apparatus for detecting edge cracks and holes in a strip according to the present invention is a detector for detecting edge cracks and holes in a strip by optical means. A light projecting section that projects light onto the body, a light receiving section installed on the opposite side of the light projecting section with the band-shaped object in between, and processing a signal from the light receiving section to divide the edge of the band-shaped object.

and a signal processing unit that generates a perforated signal; (a) the light projecting unit includes a light emitter, a glass plate that covers the light projecting surface, and a surface of the glass plate that is provided with cleaning water; (b) The light-receiving section includes a condenser lens, a light-receiving element provided near the focal point of the condenser lens, a glass plate provided on the light-receiving surface, and A cleaning liquid spraying device is provided for spraying a cleaning liquid onto the surface of the glass plate, and (c) the signal processing section includes a high-pass filter for removing low frequency components of the signal from the light receiving element, and a high-pass filter for removing the low frequency component of the signal from the light-receiving element, and controlling the level of the signal that has passed through the high-pass filter. This is a device for detecting edge cracks and holes in a strip, which is provided with a means for comparing it with a specified value and emitting a signal when the value is higher than the specified value.

[Function] Most of the light emitted from the fixed light projecting section is blocked by the steel plate, but the light that has passed through the defective section passes through the condensing lens of the light receiving section and is received by the light receiving element.

A plurality of pairs of condensing lenses and light receiving elements are installed in the width direction of the plate. The amount of change in the amount of light received by the light receiving element is sent to the signal processing section, where it is converted into a voltage, and then passed through a high-pass filter to remove low frequency components caused by light from sources other than the light emitting section. The adder adds only the corresponding voltage signals. By doing this, the voltage signals of the parts that are completely exposed to light and the parts that are not completely exposed to light can be ignored, and only the voltage signals of the parts that have actually passed through the defect and the amount of light has changed are extracted. be able to. The level of the signal that has passed through the high-pass filter is compared with a specified value in a signal processing section, and a signal is emitted when the signal level is higher than the specified value.

In addition, the front surfaces of the light emitter and light receiver are each covered with a glass plate, and during defect detection, this glass plate is cleaned by the cleaning liquid spray device installed in the light emitter and light receiver. Detectability is extremely high.

[Example code] One embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view of a light projecting section and a light receiving section, excluding a signal processing section, of an apparatus for detecting edge cracks and holes in a strip according to an embodiment of the present invention. The light projecting section 1 and the light receiving section 2 are made of a band-shaped body (
In this example, the light emitting section 1 is disposed below the strip 3, and the light receiving section 2 is disposed above the strip 3 so as to sandwich the strip 3. Although not shown in FIG. 1, two sets of the light projecting section 1 and the light receiving section 2 are arranged so as to be located at both edges of the strip 3.

First, the configuration of the light projecting section 1 will be described. The light projecting section 1 is attached to a frame 4, and uses a plurality of light emitting diodes 5 as light emitters. A glass plate 6 is attached with an inclination in the width direction of the strip 3 so as to cover the light emitting diode 5, and a cleaning liquid 7 is supplied from a cleaning liquid supply device 8 to the upper surface of the glass plate 6. Rolling oil, etc. on the surface is washed away into the drainage groove 9.

The configuration of the light receiving section 2 side is as follows.

The light receiving unit 2 is attached to the frame 10 and includes a plurality of condensing lenses 11, a plurality of light receiving elements 12 corresponding to each of the condensing lenses 11, and a signal line 13 drawn out from each of the light receiving elements 12. It consists of Then, a glass plate 14 is placed close to the lower surface of the plurality of condensing lenses 11.
is mounted horizontally. A cleaning liquid 18 supplied from a cleaning liquid tank 16 by a cleaning liquid supply pump 15 and sprayed from a nozzle 17 hits the lower surface of the glass plate 14 . Furthermore, in order to prevent dirt from adhering to this glass plate 14, a nozzle 1 is installed on the bottom surface of the glass plate 14.
9, compressed air 20 is blown. Further, a cleaning liquid receiving tray 21 is attached so as to be able to move forward and backward so that the dripping cleaning liquid does not wet the strip 3 while cleaning the lower surface of the glass plate 14. FIG. 2 is a schematic explanatory diagram of the signal processing section. A signal is inputted to the signal processing unit 22 through the signal line 13 from the light receiving element 12, and the position of the defect is determined from this signal and information such as line speed and coil number inputted from the processing calculator 23. It is displayed on the CRT 24 or printed on recording paper by the printer 25, and if there is a harmful defect, a warning lamp 26 is turned on. Further, to explain the configuration of the signal processing section 22 in detail, as shown in FIG.
8, a peak holder 29, an A/D converter 30, and an arithmetic unit 31.

With this configuration, it is possible to prevent the deterioration of defect detection ability due to rolling oil, etc., which has been a problem when detecting edge cracks and holes in the strip using an optical method. That is, in the case of this embodiment, the light projecting section 1 is covered with a glass plate 6, and the cleaning liquid 7 is continuously flowing onto the upper surface of the glass plate 6 at a rate of 10 ρ per minute. Although not shown in FIG. 1, this cleaning liquid 7 passes through many small holes and gaps provided inside the cleaning liquid supply device 8, and as it approaches the top of the cleaning liquid supply device 8, turbulence and foaming disappear. , about 1 mm installed on the top of the cleaning liquid supply device 8
A uniform laminar flow flows out from the wide slit onto the glass plate 6. In this way, the glass plate 6 is always washed with the cleaning liquid 7, and the defect detection ability does not deteriorate due to the glass plate 6 getting dirty. It is recovered and used to adjust the concentration of rolling oil. Although the light receiving part 2 does not have the problem of dripping rolling oil like the light projecting part 1, it is still contaminated by scattering and atomization of rolling oil, so a glass plate 14 is provided at the bottom of the light receiving part 2. . The cleaning liquid 18 is sprayed onto the lower surface of the glass plate 14 from the nozzle 17 by utilizing the roll change carried out at a pitch of 3 to 4 hours to wash away dirt such as rolling oil adhering to the glass plate 14. The cleaning liquid 18 that hit the glass plate falls downward, and the strip 3
In order to avoid contaminating the glass plate 14, the cleaning liquid receiver 21 slides from outside the line to the lower part of the light receiving part 2 during cleaning to receive the cleaning liquid 18.Furthermore, compressed air 20 is blown onto the glass plate 14 by a nozzle 19, This prevents dirt from adhering to the light receiving section 2.
However, it is not contaminated with rolling oil or the like to the extent that the defect detection ability is deteriorated, and a commercially available cleaning liquid with high volatility may be used as the cleaning liquid.

As described above, the amount of change in the amount of light received by the light receiving element 12 under a favorable defect detection environment is converted into voltage, and
The signal is guided to the signal processing section 23 by the signal processing section 23. and signal processing section 2
3, the strip 3 is calculated based on this signal and information such as the line speed and coil number input from the process calculator 23.
Determine the location and size of edge cracks and holes.

The results are displayed on the CRT 24 or printed on recording paper by the printer 25. The signal processing situation in the signal processing unit 23 will be explained in detail with reference to FIG.
The amount of change in the amount of light converted to voltage is passed through a high-pass filter 27 to remove low frequency components due to light from sources other than the light projecting section 1, and a voltage signal of the portion where the amount of light has changed after actually passing through the defective part is obtained. only is taken out. The extracted signals are then added in the width direction of the strip by an adder 28. This summed signal is transmitted by strip 3 at 1.0% per minute.
If you try to detect a hole with a diameter of 1 mm while passing at 800 m, the high frequency of 30 KHz will be generated, making post-processing difficult, so only the peak value of the signal should be held for 20 m5 with the peak holder 29. ing. The held signal is A/D converted by an A/D converter and input to the arithmetic unit 30. Then, as mentioned above, the arithmetic unit 3
0, the position and size of edge cracks and holes in the strip 3 are determined and displayed on the CRT 24 or printed on recording paper by the printer 25. Further, a specified value of abnormal defects is inputted in advance to the calculator 30, and this value is compared with the input signal, and when the signal is higher than this specified value, the warning lamp 26 is turned on.
is now lit.

Note that although the light projecting section and the light receiving section may be fixed, defects can be detected more effectively if they are moved in the width direction of the strip depending on the width of the strip.

[Effects of the Invention] The device for detecting edge cracks and holes in a strip according to the present invention detects edge cracks and holes in a strip in a bad environment where the light emitting part and the light receiving part are contaminated with rolling oil or the like. Since detection can be performed with high detection ability and an inexpensive and compact detection device can be provided, its industrial effects are great.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a detector according to an embodiment of the present invention, FIG. 2 is a schematic explanatory diagram of a signal processing section, and FIG. 3 is a detailed explanatory diagram of the signal processing section. DESCRIPTION OF SYMBOLS 1...Light emitter, 2...Light receiver, 3...Strip, 4...Frame, 5...Light emitting diode, 6...
- Glass plate, 7... Cleaning liquid, 8... Cleaning liquid supply device, 9... Drainage groove, 10... Frame, 11... Condensing lens, 12... Light receiving element, 13... Signal line, 1
4... Glass plate, 15... Cleaning liquid supply pump, 16
...Cleaning liquid tank, 17...Nozzle, 18...Cleaning liquid, 19...Nozzle, 20...Compressed air, 21.
...Cleaning liquid saucer, 22...Signal processing unit, 23...Process calculator, 24...CRT, 25...Printer, 26...Alarm lamp, 27...High pass filter, 28... ...Adder, two...Peak holder, 30...A/D converter, 31...Arithmetic unit.

Claims (1)

[Scope of Claims] A detector for detecting edge cracks and holes in a strip-shaped body by optical means, comprising: a light projecting section that projects light onto the strip-shaped body; a light receiving section installed on the opposite side of the light receiving section; and a signal processing section that processes the signal from the light receiving section to generate a signal indicating edge cracks and holes in the strip; The light part is provided with a light emitter, a glass plate that covers the light projection surface, and a cleaning water supply device that supplies cleaning water to the surface of the glass plate; (b) the light receiving part is provided with a condensing lens; , a light-receiving element provided near the focal point of the condenser lens, a glass plate provided on the light-receiving surface, and a cleaning liquid spraying device for spraying cleaning liquid onto the surface of the glass plate; (c) the signal processing unit; is characterized by a high-pass filter that removes low-frequency components of the signal from the light-receiving element, and a means for comparing the level of the signal passing through the high-pass filter with a specified value and emitting a signal when the level is higher than the specified value. A device for detecting edge cracks and holes in strips.