JP2629362B2 - Laser Emitter / Receiver Failure Monitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser beam projecting / receiving device that projects a laser beam, detects the passage or interruption of the laser beam, and detects the presence or absence of an object to be detected. The present invention relates to a device for monitoring a failure of a laser beam projecting / receiving device.

[Conventional technology]

For example, in a take-up device of a rolling line, a laser projector and a light receiver are disposed opposite to each other between a pinch roll and a mandrel, and a steel sheet discharged from the pinch roll is passed between the laser projector and the light receiver, and a laser beam is emitted. By detecting the timing at which the wrapper roll is cut off, the tip of the steel plate is detected, and the jump timing of the wrapper roll arranged on the mandrel is controlled.

The light receiving sensitivity of the laser light emitting and receiving device gradually decreases due to contamination of the lens due to long-term use, a decrease in the light emitting efficiency of the laser diode of the projector, and the like. If the apparatus is used with such a decrease in the light receiving sensitivity, it may be erroneously detected that the laser beam is shut off even though the object to be detected does not exist, thereby causing a malfunction of the apparatus. .

Conventionally, there has been no means for detecting such a decrease in the light receiving sensitivity, and it has only been known that the light receiving sensitivity has decreased after a malfunction has occurred.

[Problems to be solved by the invention]

If the decrease in the light receiving sensitivity is not known until the malfunction occurs as in the prior art, the machine may malfunction and a product failure or an accident may occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a failure monitoring device for a laser light emitting and receiving device which directly detects a decrease in light receiving sensitivity of the laser light emitting and receiving device and prevents a malfunction before it occurs.

[Means for solving the problem]

The present invention relates to a laser light projecting / receiving device that projects a laser beam and detects the passage or cutoff of the laser beam to detect the presence or absence of a detected object. A light receiving signal level detecting means for detecting a light receiving signal level of the laser light; and a laser light abnormality determining means for outputting a laser light abnormality determining signal when the detected light receiving signal level falls below a predetermined light receiving signal level limit. It is provided.

(Operation)

According to the present invention, the light receiving signal level decreases due to the decrease in the light receiving sensitivity, and when the light receiving signal level falls below the light receiving signal level limit, a laser light abnormality determination signal is output, indicating that the light receiving sensitivity has decreased.

〔Example〕

One embodiment of the present invention will be described below. Here, a case will be described in which the present invention is applied to a laser light emitting and receiving device for detecting the leading end of a steel plate in a winding device. FIG. 2 shows an outline of a winding device to which the present invention is applied. The steel sheet 10 rolled by the rolling mill is fed onto a mandrel 16 by being driven by an upper pinch roll 12 and a lower pinch roll 14. The pulse generator 11 for detecting the feeding speed of the steel plate 10 is provided on the lower pinch roll 14. Between the upper pinch roll 12, the lower pinch roll 14, and the mandrel 16, a laser projector 21 and a photodetector 23 are disposed as laser projection and reception devices in order to detect the tip position of the steel plate 10.

4 wrapper rolls 18 on the outer circumference of the mandrel 16
Are arranged. The wrapper roll 18 is driven to rotate by driving means (not shown). Wrapper roll 18 is a fulcrum
Reference numeral 18 is attached to an arm 20 that is rotatable about a fulcrum 22, and is moved toward and away from the outer peripheral surface of the mandrel 16 by driving a hydraulic cylinder 24. The height position of the wrapper roll 18 with respect to the outer peripheral surface of the mandrel 16 is detected by the rotating magnescale 25 as the rotation angle of the arm 22.

The hydraulic cylinder 24 is driven by the servo valve 30, and the hydraulic pressure is detected by the pressure detectors 26 and 28.

In FIG. 2, the arrangement of sensors and the control system are shown only for one wrapper roll, and the other three wrapper rolls are not shown.

An AJC (Automatic Jumping Control) control panel 32 receives detection signals from the various sensors and drives the hydraulic cylinders 24 individually via the servo valve 30 to thereby control the mandrel 16 by the wrapper roll 18.
CPR (Constant Pressure Rolling) control to make the pressing force constant against, and the wrapper roll 18 jumps every time the tip of the steel sheet 10 wound on the mandrel 16 arrives. CPC (Constant Position Positioning) to prevent the roll holding mark from sticking to the product after a specified distance
Control) Control is performed instead of CPR control. Both CPR control and CPC control are performed by servo control. The timing at which the tip of the steel sheet 10 wound on the mandrel 16 arrives depends on the feeding speed of the steel sheet 10 detected by the pulse generator 11 and the laser beam cutoff detected by the laser light emitting and receiving devices 21 and 23. The calculation can be calculated based on the timing, and the switching between the CPR control and the CPC control is performed based on the calculated timing.

The failure monitoring device 34 performs various failure monitoring based on various sensor signals to display a failure alarm, and displays a control mode, a jump waveform, and the like on a CRT screen or the like.

The failure monitoring items are control abnormalities of the wrapper roll 18 (CPC
Control loop abnormality, jump timing deviation, CPR control loop abnormality, etc.), the jump response, jump height, jump waveform,
Monitoring is performed based on a change in the height of the wrapper roll 18 during the CPR control. In addition, deterioration of the pilot servo valve of the servo valve 30 (wear of the srule edge portion, deterioration of the voice coil portion),
Failures such as breakage of the pilot servo valve bellows frame are monitored by servo valve neutral current, servo valve hysteresis, etc. In addition, abnormalities of the laser light emitting / receiving devices 21 and 23 (dirt of the laser light emitting / receiving device lens, reduction of laser diode light emission efficiency, etc.) are monitored by a light receiving signal from the light receiving device 23.

FIG. 1 shows an embodiment of a failure monitoring device for the laser light emitting and receiving devices 21 and 23 to which the present invention is applied. Failure monitoring is performed for each coil by projecting laser light L from the laser projector 21 prior to winding. The light receiver 23 receives the laser light L
Is received. The light receiving signal level detecting means 36 detects the light receiving signal level. The laser sensitivity margin conversion means 38 converts the received light signal level into a received light sensitivity margin PH as shown in the following table, for example, according to the broken line approximation in FIG.

The comparing means (laser light abnormality determining means) 40 compares the value PH _ALM set as the light receiving signal level limit value with the above light receiving sensitivity margin PH, and outputs a laser light abnormality determining signal when PH _ALM > PH, Display a failure alarm. This indicates that the light receiving sensitivity has decreased.

The sample holding means 42 is a laser light sensitivity margin converting means 38.
The sensitivity margin PH calculated in is stored for, for example, the latest 10 coils. In addition, the average of one day or the largest of the one day is stored for about 100 days. The display means 44 displays the stored data in chronological order, for example, as shown in FIG. The operator can see the display to know the change tendency of the sensitivity margin PH, and can use it as a guide for the timing of component replacement and lens dirt cleaning.

〔The invention's effect〕

As described above, according to the present invention, it is possible to directly detect a decrease in the light receiving sensitivity of the laser light emitting and receiving device, so that a malfunction can be prevented. Also, by storing the light receiving signal levels for a plurality of samples and displaying them in chronological order on one screen, it is possible to know the changing tendency of the light receiving sensitivity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing an outline of a winding device to which the present invention is applied. FIG. 3 is a diagram showing a broken line approximation of the light receiving signal level. FIG. 4 is a diagram showing laser reception sensitivity margin data displayed on the display means of FIG. 10 ... Steel plate (detected object), 21 ... Laser projector, 23 ...
Light receiver, 36: light reception signal level detection means, 40: comparison means (laser light abnormality determination means), 42: sample storage means, 44: display means, L: laser light.

Claims (2)

(57) [Claims] A laser beam projecting / receiving device for projecting a laser beam and detecting the passage or interruption of the laser beam to detect the presence / absence of an object to be detected. Light-receiving signal level detecting means for detecting a light-receiving signal level at the time; and laser light abnormality determining means for outputting a laser light abnormality determining signal when the detected light-receiving signal level falls below a predetermined light-receiving signal level limit. A failure monitoring device for a laser light emitting and receiving device comprising: 2. The apparatus according to claim 1, further comprising: sample storage means for storing the detected light reception signal levels for a plurality of samples; and display means for displaying the stored data on a single screen in chronological order. Monitoring system for laser light emitting and receiving devices.