JPH02210248A - Pinhole detecting device for cylinder body - Google Patents

Abstract

PURPOSE:To detect a pinhole continuously at a high speed by providing a plate type optical waveguide body with a conic reflecting surface and guiding light which is made incident through the pinhole on an optoelectric element. CONSTITUTION:An annular lamp 3 and the optical waveguide body 4 are arranged fixedly and the cylinder body 2 to be inspected is moved in the direction where the optical waveguide body 4 is put in. The optical waveguide body 4 is made of an acryl plate, etc., and has a photodetection surface 41 formed at the outer periphery and the conic reflecting surface 42 on the center optical axis, and reflecting plates 43 and 44 are arranged on both surfaces. Then if the cylinder body 2 has the pinhole 10, the light beam from the lamp 3 is made incident on the photodetection surface 41 through the pinhole 10 and reflected by the reflecting surface 42 to reach a photodetecting element 5. At this time, the element 5 generates a detection signal, which is inputted to a comparator 6 through a cord 8; and the comparator 6 compares the reference signal from a setter 9 with the detection signal of the element 5 to detect whether or not there is the pinhole.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an apparatus for optically detecting pinholes in a cylindrical inspection object.

Conventional technology Pinhole detection in a cylindrical body such as a vibrator is accomplished by placing many photoelectric sensors facing the entire circumference of the cylindrical body, or by placing a mirror at the tip of an optical fiber and rotating this mirror. , one photoelectric sensor detects the entire inner peripheral surface of the cylindrical body. In a device using a plurality of photoelectric sensors, the area occupied by the sensors becomes large, so that only large-diameter cylindrical bodies can be detected.

Additionally, mirror rotation systems require rotational movement during inspection, making them unsuitable for high-speed inspection of extruded pipes and the like, and are prone to malfunctions due to ambient light.

Under these circumstances, a small and simple detection device is desired.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to miniaturize the entire device using one photoelectric sensor and to be able to detect pinholes continuously and at high speed.

SUMMARY OF THE INVENTION Therefore, the present invention provides a method for disposing a light outside a cylindrical body to be inspected, and arranging a light guide in the shape of the cylindrical body, and forming a light guide on this light guide. A conical reflecting surface guides the illumination light incident from the pinhole to one photoelectric element, and a comparator compares the electrical signal output from this photoelectric element with a reference signal. The presence or absence of holes is detected.

In this way, by using a plate-shaped light guide and a conical reflective surface on its optical axis, the entire circumference of the cylindrical object to be inspected can be detected at once, making the pinhole detection device compact. It also enables continuous high-speed inspection.

Structure of the Invention FIG. 1 shows a pinhole detection device 1 of the invention.

This pinhole detection device l is composed of an illumination 3 placed around the outer periphery of a cylindrical body 2 to be inspected, a light guide 4 inserted into the cylindrical body 2, a photoelectric element 5, and a comparator 6. There is.

The illumination 3 is, for example, an annular fluorescent lamp or the like, and is disposed in a movable manner relative to the cylindrical body 2 together with the light guide 4 . In addition, the light guide 4
is a plate-shaped body made of, for example, acrylic, and forms a light-receiving surface 41 that adapts to the shape of the cylindrical body 2 on its outer peripheral surface, and also forms a conical reflecting surface 42 on the central optical axis. . Then, both sides of this light guide 4 are provided with reflective plates 43 and 44 as necessary.
is installed. Note that the reflecting plate 43 on the apex side of the reflecting surface 42 forms a window 45 on the optical axis. Also,
The photoelectric element 5 is, for example, a phototransistor, and the window 45 is placed on the optical axis of the light guide 4 by the holder 7.
is placed at a predetermined distance from. In addition to the photoelectric element 5, the holder 7 is also integrated with the light guide 4 at its tip. This photoelectric element 5 is connected to one input end of a comparator 6 by a cord 8. The other input end of the comparator 6 is connected to a setting device 9 such as a resistor for generating a reference signal.

Effect of the invention When detecting a pinhole in the detection object 2, the illumination 3 and the light guide 4 are normally fixedly arranged at a predetermined distance, whereas the cylindrical object 2 to be inspected is moves in a direction to put the light guide 4 inside.

If a pinhole 10 exists in the cylindrical body 2 during this movement, the light beam from the illumination 3 passes through the pinhole IO,
The light enters the light receiving surface 41 of the light guide 4, and depending on the angle of incidence,
The light reaches the reflective surface 42 directly, or reaches the reflective surface 42 while repeating total internal reflection, and is reflected there and reaches the light receiving element 5. At this time, since the light-receiving surface 41 is formed along the entire circumference along the inner circumference of the light guide 4, even if the pinhole 10 is present at an irregular position in the cylindrical body 2,
All of the incident light from the pinhole 10 reaches the reflective surface 42. Moreover, this reflective surface 42 is 45° on the optical axis.
Since the pinhole 10 is formed as a conical surface at an angle of , it is always guided in the direction of the charging element 5 regardless of the position of the pinhole 10 .

Note that the distance between the light guide 4 and the photoelectric element 5 is determined depending on the directivity of the light receiving element 5, and a condensing lens may be interposed between them if necessary. If in this detection process,
Even if disturbance light is incident, it is blocked by the two reflecting plates 43 and 44, so that the disturbance light is transmitted to the light receiving surface 41.
does not enter the inside of the light guide 4. Therefore, malfunctions caused by ambient light can be prevented by the presence of the reflectors 43 and 44.

Therefore, the light receiving element 5 generates an electrical detection signal according to the amount of light, and sends this to one input terminal of the comparator 6. Here, the comparator 6 compares the magnitude relationship between the reference signal from the setting device 9 and the detection signal from the photoelectric element 5, and when the detection signal is larger than the reference signal,
Generates an output signal corresponding to the presence of a pinhole. In this way, pinhole inspection of the cylindrical body 2 to be detected is performed continuously.

Of course, the shape of the light guide 4 is formed so as to match the cross-sectional shape of the cylindrical body or rectangular cylindrical body to be inspected. Therefore, a plurality of light guides 4 are prepared according to the shape of the cylindrical body 2, and a plurality of light guides 4 are prepared depending on the shape of the cylindrical body 2 to be inspected.
can be selectively attached depending on the shape of the

Effect of the invention The present invention provides the following effects.

Inside the cylindrical body, the light guides face each other with their light-receiving surfaces and receive the light from the illumination outside the cylindrical body on their entire circumferential surface, eliminating the need for multiple light-receiving elements and simplifying the light-receiving part. can be converted into

In addition, since all the incident light from all sides of the cylindrical body to be inspected is focused on the optical axis by the reflective surface of the light guide, it is only necessary to have one photoelectric element on the optical axis, so it can be used in all directions. of incident light is captured by one light receiving element.

In the process of detecting photoelectricity from pinholes, there are no rotating parts, so the relative movement of the cylindrical body, lighting, light guide, etc. can be set at high speed, making it possible to perform high-speed inspections during the extrusion molding process. Become.

Furthermore, if a reflecting plate is formed on the surface of the light guide, malfunctions caused by ambient light will be eliminated, thereby increasing the reliability of pinhole detection.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a pinhole detection device for a cylindrical body according to the present invention, seen from the side, and FIG. 2 is a front view of the device. ■...Pinhole detection device for cylindrical body, 2...Cylindrical body, 3
...Lighting, 4..Light guide, 41..Light receiving surface, 42..Reflecting surface, 43.44..Reflecting plate, 45..Window, 5..Photoelectric element, 6..Comparator, 7.. Holder 8: Code, 9: Setting device.

Claims (2)

[Claims] (1) A lighting device placed around the outer periphery of the cylindrical body to be inspected, and a light guide that can be inserted into the cylindrical body, has a light-receiving surface on the outer periphery, and has a conical reflective surface on the optical axis. A photoelectric element placed at a predetermined distance on the optical axis of the light guide on the vertex side of the reflective surface, and a comparator that compares the magnitude of the detection signal from this photoelectric element with a reference signal. A pinhole detection device in a cylindrical body characterized by the following. (2) The pinhole detection device for a cylindrical body according to claim 1, characterized in that the light guide is plate-shaped, and a reflecting plate is attached to a surface other than the light-receiving surface.