JPH0521223U - Detection head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a detection head which protects the tip end surface of an optical fiber made of plastic from oil, thereby enabling stable measurement for a long period of time. [Structure] The detection head 22b constitutes a case 24 together with a tubular portion 26, and a pair of three plastic light beams are formed on each of three surfaces of a cap 28 having a triangular pyramid-shaped tip. A glass window 30 which transmits light is adhered by an adhesive so as to cover the tip surfaces of the fibers 8 and 10 all together.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a detection head used in, for example, an inner surface inspection device for a cylindrical object or an optical fiber type photoelectric switch.

[0002]

[Prior Art]

 For example, one of the mechanical parts such as automobile parts is a cylindrical object which has a cylindrical shape and whose inner surface is mirror-finished to some extent in order to minimize friction with the shaft passing therethrough. .. If such a cylindrical object has scratches or the like on its inner surface, it may cause galling or seizure.

[0003] Therefore, conventionally, the internal state of each of the above-described cylindrical products that are mass-produced has been inspected by visual inspection. However, the visual inspection requires a lot of manpower, which is very troublesome. In addition to the above problem, there is a problem that the inspection is inaccurate because the judgment of pass / fail varies depending on the inspector. It has been previously proposed (for example, Japanese Patent Laid-Open No. 3-118451).

To summarize one example, as shown in FIG. 4, this device has, for example, a plurality of optical fibers 8 for projecting light and multiple optical fibers 10 for receiving light (however, in FIG. 4, one optical fiber 8 is provided). Each is shown). The one ends of the optical fibers 8 and 10 are combined into one by the detection head 22.

A light source 4 for emitting a light 6 is provided at an end of the light projecting optical fiber 8 opposite to the detection head 22, and the light 6 from the light source 4 is supplied to the optical fiber 8. I have to. At the end of the optical fiber 10 for receiving light on the side opposite to the detection head 22, there is provided a photodetector 16 for receiving the light (reflected light) 14 guided by the optical fiber 10 and converting it into an electric signal. There is.

Then, the electric signal from the light receiver 16 or the electric signal based on the electric signal is supplied to the comparison circuit 18, and compared therewith with a predetermined reference value.

Further, in this example, the detection head 22 is fixed, and the tubular body 2 is moved up and down as shown by an arrow A by the drive device 20 to insert the detection head 22 into the tubular body 2. I am trying to do it.

When the detection head 22 is inserted into the cylindrical object 2 with the light 6 emitted from the light source 4, the light 6 guided through the optical fiber 8 for projecting is emitted from the detection head 22 to form a cylindrical shape. The inner surface 2a of the object 2 is irradiated. At this time, if, for example, a scratch is present on the inner surface 2a, diffuse reflection occurs there, and the reflected light 14 enters the light receiving optical fiber 10 in the detection head 22. However, the inner surface 2a of the tubular member 2 is not a perfect mirror surface, and therefore some diffuse reflection occurs regardless of the presence of scratches, etc., but the amount of reflected light 14 is greater when scratches or dust are present. Will naturally grow.

Then, the reflected light 14 as described above is guided to the light receiver 16 through the optical fiber 10 and converted into an electric signal there, and the magnitude of the electric signal or the electric signal based on the electric signal is calculated by the comparison circuit 18 as a reference value. Compared to. Therefore, if an appropriate reference value is set in the comparison circuit 18, the detection signal S is output from the comparison circuit 18 when the inner surface 2a of the tubular object 2 has scratches, dust, or the like. The state of the inner surface 2a of the tubular object 2 can be determined.

The tip of the detection head 22 may be simply flat as shown in FIG. 4, but in order to improve the detection accuracy and the like, the tip of the detection head 22 is formed into a triangular pyramid shape by the applicant of the present application. (Japanese Patent Application No. 2-269219).

The structure of such a detection head will be described with reference to FIGS. 5 and 6. The detection head 22a is composed of a case 26 and a cap 28 having a triangular pyramid-shaped tip. Has 24. Then, one end side and a plurality of (more specifically, three as shown in FIG. 6) of the plurality of (more specifically, six as shown in FIG. 6) light projecting optical fibers 8 as described above are provided. One end of the optical fiber 10 for receiving light) is housed in the case 24, and the tip ends of the optical fibers 8 and 10 are directed outward with respect to the central axis of the detection head 22a. The tip surfaces of Nos. 8 and 10 are exposed from the three surfaces of the cap 28 as shown in FIG. In this way, by directing the optical fibers 8 and 10 to the outside, it is possible to limit the inspection area and inspect the inner surface state of the cylindrical object 2. Therefore, it is easy to detect small scratches and the detection accuracy is improved. ..

[0012]

[Problems to be solved by the device]

 The optical fibers 8 and 10 are made of a plastic optical fiber because of their large flexibility, easy processing, the ability to make a thick one (for example, about 1 mmφ), and the low price. It is used.

However, oil such as cutting oil and rust preventive oil is attached to the tubular member 2, and the detection head 22a (and the detection head 22) is used under the condition that such oil is easily attached. However, since the tip surfaces of the optical fibers 8 and 10 are exposed, the oil adheres to the exposed surfaces, and the chemical substances contained in the oil, particularly amines, cause long-term changes. There is a problem that the optical fibers 8 and 10 are cracked and the light transmittance is lowered during the period of use, and in such a case, stable measurement cannot be performed.

Such a problem is caused not only by the detection heads 22 and 22a for the inner surface inspecting apparatus for a cylindrical object as described above, but also when the detection heads for an optical fiber type photoelectric switch are attached with oil. It may be used under easy conditions, in which case the same problems as above occur.

Therefore, the present invention provides a detection head that protects the tip end surface of the above-mentioned plastic optical fiber from oil, thereby enabling stable measurement for a long period of time. The main purpose is that.

[0016]

[Means for Solving the Problems]

 In order to achieve the above object, the detection head of the present invention is characterized in that a glass window that transmits light is provided so as to cover at least the tip surfaces of the respective optical fibers as described above.

In this case, the glass window may be adhered to the case by using a transparent and oil-resistant adhesive, and it is preferable to use an amine-free adhesive.

[0018]

[Action]

 According to the above configuration, since the tip surface of each optical fiber is protected by the glass window, oil is prevented from adhering to the tip surface of each optical fiber even when used under conditions where oil tends to adhere. .. Even if oil adheres to the glass window, the glass is stable against oil, so there is no risk of deterioration. As a result, the optical fiber made of plastic will not be cracked or the transmittance of light will not decrease, and stable measurement can be performed for a long period of time.

[0019]

【Example】

 FIG. 1 is an enlarged sectional view showing a detection head according to an embodiment of the present invention. FIG. 2 is a front view showing one of the front faces of the tip of the detection head of FIG. 1 as seen from the P direction. The same or corresponding portions as those of the conventional example of FIG. 4 or the prior example of FIG. 5 are designated by the same reference numerals, and the differences from those are mainly described below.

In the detection head 22b of this embodiment as well, the tip portion of the cap 28 forming the case 24 has a triangular pyramid shape, and the optical fibers 8 and 10 made of plastic as described above are provided on each of the three surfaces. Are arranged so that they can be seen from the outside. Also in this embodiment, one optical fiber 10 for receiving light and two optical fibers 8 for projecting the optical fiber 10 sandwiching the optical fiber 10 are arranged as a set.

Then, light is transmitted (more specifically, transparent) so as to collectively cover the tip surfaces of the three optical fibers 8 and 10 forming a set on each of the three surfaces of the cap 28. A thin (for example, about 0.3 mm) glass window 30 having an oval shape is attached.

Although various means can be adopted for attaching the glass window 30, in this embodiment, the concave portions 28a are provided on each of the three surfaces of the cap 28, and the glass window 30 is provided on the concave portion 28a. It is fitted so as to be aligned with the surface, and the surface of the glass window 30 excluding the surface is bonded to the cap 28 and the optical fibers 8 and 10 with an adhesive. 28b in FIG. 2 is a concave portion for applying an adhesive.

According to the above configuration, the front end surfaces of the optical fibers 8 and 10 are protected by the glass window 30, so that the detection head 22b is, for example, the inner surface inspection device for the cylindrical object 2 shown in FIG. Even in the case where it is used under a condition where oil is likely to adhere, as in the case of 1, the oil is prevented from adhering to the tip surfaces of the optical fibers 8 and 10. Even if oil adheres to the glass window 30, since the glass is stable against oil, there is no fear of deterioration. As a result, the optical fibers 8 and 10 made of plastic will not be cracked or the light transmittance will not decrease, and stable measurements can be performed for a long period of time.

In the above case, it is preferable to use, as an adhesive agent for adhering the glass window 30, an adhesive agent having high transparency, oil resistance and stable for a long period of time (in particular, the transparency is not deteriorated). By doing so, even if the adhesive enters between the tip surfaces of the optical fibers 8 and 10 and the glass window 30, it is possible to perform stable measurement and the like for a long period of time without lowering the light amount.

Further, it is preferable to use an amine-free adhesive as the above-mentioned adhesive, and by doing so, the adhesive will crack the plastic optical fibers 8 and 10 and reduce the light transmittance. It will be possible to perform stable measurements over a longer period of time.

Specific examples of materials that satisfy the conditions of transparency, oil resistance, and amine-free property include epoxy-based or silicone-based adhesives.

The glass window 30 need only cover at least the tip surfaces of the optical fibers 8 and 10, and thus may cover a larger area than that shown in FIGS. Further, the glass window 30 does not necessarily have to be embedded in the tip portion of the case 24, and may be exposed from the tip portion of the case 24.

Further, the present invention is not limited to the detection head 22b having a triangular pyramid-shaped tip as in the above example, and the shape of the tip is not limited to that shown in FIG. 4, for example. It may be flat.

Further, the present invention is directed to detection heads other than the detection head 22b for the inner surface inspection device for a cylindrical object as in the above example, for example, detection for an optical fiber type photoelectric switch using an optical fiber made of plastic. It can also be applied to the head. Even in an optical fiber type photoelectric switch, the detection head for light projection, light reception, or both light reception and reception can be placed in a narrow space. Often used in.

FIG. 3 shows an example of a detection head for an optical fiber type photoelectric switch. The detection head 22c accommodates one end side of the plastic optical fiber 12 in a case 24 having a fixing screw portion 24b on the outer peripheral portion, and a transparent glass window 30 is attached to the front end surface of the case 24. It is a thing. In the case of a transmission type photoelectric switch, at least one optical fiber 12 is required for emitting or receiving light. In the case of a reflection type photoelectric switch, the optical fiber 12 is for emitting and receiving light. There should be at least one for each. The method of attaching the glass window 30, the adhesive agent for the same, and the like are the same as in the case of the detection head 22b for the cylindrical object.

In any of the detection heads 22b and 22c, the glass window 30 may be an optical filter that transmits only light of a specific wavelength (more specifically, the wavelength of the light source used). By doing so, it is possible to significantly reduce the disturbance light from entering the optical fiber from the tip end surface, so that the so-called SN ratio is improved and the measurement or the like can be performed more accurately. Further, the number of parts and the space can be reduced as compared with the case where an optical filter having the same purpose is separately provided.

[0032]

[Effect of the device]

 As described above, according to the present invention, since the front end surface of the optical fiber made of plastic can be protected from oil by the glass window, even if the optical fiber is used under conditions where oil is likely to adhere, the optical fiber is not cracked or cracked. The decrease in light transmittance will not occur and stable measurements can be performed for a long time.

If the glass window is adhered to the case with a transparent and oil-resistant adhesive, the light amount does not decrease even if the adhesive enters between the tip surface of the optical fiber and the glass window. It becomes possible to perform stable measurements for a long period of time.

Further, when the adhesive does not contain an amine, the adhesive does not cause cracks or a decrease in light transmittance in the plastic optical fiber, and the adhesive is used for a longer period of time. It becomes possible to perform stable measurement and the like.

Further, when the glass window is used as an optical filter, the SN ratio is improved, so that the measurement and the like can be performed more accurately, and in comparison with the case where an optical filter having the same purpose is separately provided. The number of parts and the space can be reduced.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a detection head according to an embodiment of the present invention.

FIG. 2 is a front view showing one of the front end surfaces of the detection head of FIG. 1 as seen from the P direction.

FIG. 3 is an enlarged sectional view showing a detection head according to another embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing an example of an inner surface inspection device for a cylindrical object.

FIG. 5 is an enlarged cross-sectional view showing a prior art example of a detection head.

6 is a front view showing the front surface of the tip of the detection head of FIG. 5. FIG.

[Explanation of symbols]

 8,10,12 Plastic optical fiber 22b, 22c Detection head 24 Case 30 Glass window

Claims (6)

[Scope of utility model registration request] 1. A detection head comprising one or more plastic optical fibers, one end side of which is housed in a case so that the front end surface of the optical fibers can be seen from the outside. A detection head, which is provided so as to cover the tip surface of the. 2. The detection head according to claim 1, wherein the glass window is bonded to the case with a transparent and oil-resistant adhesive. 3. The detection head according to claim 2, wherein the adhesive is an amine-free adhesive. 4. The detection head according to claim 3, wherein the adhesive is an epoxy-based or silicone-based adhesive. 5. The detection head according to claim 1, wherein the glass window is an optical filter. 6. The optical fiber comprises one or more light projecting optical fibers and one or more light receiving optical fibers, and the detection head is used for inspecting the inner surface of a cylindrical object. The detection head according to claim 1, 2, 3, 4 or 5.