JPH04145347A - Inner surface inspection device for tubular matter - Google Patents

Abstract

PURPOSE:To conduct the irradiation of light rays in concentration to a narrow sphere in the vicinity of a detection head, and conduct the inspection of the inner surface condition of a tubular matter by limiting an inspection sphere, by directing respective optical fibers for light projecting and for light receiving, toward the outside. CONSTITUTION:An inspection head 22 is made up by gathering one end side of plural light projecting optical fibers 8 and one end side of plural light receiving optical fibers 10 into one, and is also insertable to the inside of a tubular matter 2. The tip portions of optical fibers 8, 10 are directed to the outside at predetermined angles against the center axis 22a of the head 22. As respective light projecting optical fibers 8 and the light receiving optical fibers 10 are directed to the outside against the center axis 22a, the inspection of the inner surface condition of the matter 2 can be conducted by irradiation of light rays 6 in concentration to a narrow sphere which is at the inner surface 2a of the matter 2 and in the vicinity of the tip portion of the head 22, and limiting an inspection sphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an inner surface inspection device for a cylindrical object, which inspects the inner surface of a cylindrical object for the presence of scratches, adhesion of dust, etc.

[Background technology]

For example, one of the mechanical parts such as automobile parts is a cylindrical object whose inner surface is mirror-finished to a certain extent in order to minimize the friction between it and the shaft passing through it. .

If such a cylindrical object has scratches or the like on its inner surface, it may cause galling, seizure, etc.

Therefore, in the past, the inner surface condition of each mass-produced cylindrical article as described above was visually inspected.

However, there is a problem in that visual inspection requires manual labor and is very time-consuming.

There is also the problem that the test is not accurate because the pass/fail judgment varies depending on the inspector.

Therefore, an apparatus for inspecting the inner surface of a cylindrical object that can solve these problems has been previously proposed by the applicant of the present application (Japanese Patent Application No. 1-256225).

To summarize and explain the example, as shown in Fig. 8,
This device includes, for example, a plurality of optical fibers 8 for projecting light and a plurality of optical fibers 10 for receiving light (however, one each is shown in FIG. 8). For example, as shown in FIG. 9, one end of each optical fiber 8.10 is bundled in the detection head 12 so that they intersect with each other almost equally. 12a is a sheath.

A light source 4 that emits light 6 is provided at the end of the light projecting optical fiber 8 opposite to the detection head 12, and the light 6 is supplied into the optical fiber 8. .

Further, at the end of the optical fiber 10 for light reception opposite to the detection end 12, the light guided by the optical fiber 10 (
A light receiver 16 is provided which receives reflected light (light) 14 and converts it into an electrical signal.

Then, the electrical signal from the light receiver 16 or the electrical signal based thereon (for example, processed by amplification, conversion, etc.) is supplied to the comparison circuit 8, where it is compared with a predetermined reference value.

At the time of inspection, the detection head 12 is set, for example, at the inlet end of the cylindrical object 2 to be inspected, as shown in FIG.

In that case, by making the area around the cylindrical object 2 dark, etc., the cylindrical object 2
It is preferable to prevent disturbance light and extra reflected light from entering the inside of the device, which may cause noise.

When light 6 is output from the light source 4 in such a state, this light 6 is guided through the optical fiber 8 and hits the cylindrical object 2.
is irradiated onto the inner surface 2a of.

At this time, light 6 is emitted from each optical fiber 8 for light projection in the detection head 12 with a certain degree of spread (for example, about 60 degrees), as shown in FIG. 10, for example.

In that case, if the inner surface 2a of the cylindrical object 2 is a perfect mirror surface and there are no scratches or dust, the reflected light from the inner surface 2a (in this specification, diffused On the other hand, if there is a scratch 2b on the inner surface 2a, for example, as shown in FIG.
Enters 0.

However, the inner surface 2a of the cylindrical object 2 is actually not a perfect mirror surface, so diffuse reflection occurs regardless of the presence or absence of scratches 2b, etc., but the reflected light 14
Naturally, the amount of light increases.

Then, the reflected light 14 as described above is guided to the light receiver 16 by the optical fiber 10 for light reception, where it is converted into an electric signal, and the magnitude of the electric signal or the electric signal based on it is compared with the reference value in the comparison circuit 18. be compared.

Therefore, if an appropriate reference value is set in the comparison circuit 18, when there are scratches, dust, etc. on the inner surface 2a of the cylindrical object 2, the detection signal S will be output from the comparison circuit 18, and this will cause The state of the inner surface 2a of the cylindrical object 2 can be determined.

In this way, the above-mentioned inner surface inspection device allows inspection of the inner surface condition of a cylindrical object, such as the presence of scratches and the presence or absence of dirt attached, easily and quantitatively, unlike conventional visual inspections. It can be done accurately because it is accurate. Therefore, such an internal surface inspection device can save labor during inspection, and is particularly effective when, for example, a large number of cylindrical objects are continuously inspected.

Further, the detection head 1 is moved by moving at least one of the detection head 12 and the cylindrical object 2 by a drive device (not shown).
2 into the cylindrical object 2, it is possible to inspect the scratches, etc., existing on the inner surface 2a of the cylindrical object 2 from a closer distance. Since the difference in the amount of reflected light 14 between the two images increases and the so-called signal-to-noise ratio improves, more accurate inspection becomes possible. Moreover, it can be applied even when the cylindrical object 2 is thin and long.

[Purpose of the invention]

However, in the above device, the light emitting optical fiber 8 and the light receiving optical fiber 10 are arranged in the detection head 12 parallel to the central axis of the detection head 12, so as can be seen from FIG. , the inner surface 2a of the cylindrical object 2
Since only a very small amount of the light 6 spread and emitted from the optical fiber 8 is irradiated onto the predetermined area of the inner surface 2a,
There is still room for improvement in that the amount of light 6 irradiated to the scratches 2b, etc. present on the surface is small, and therefore the amount of reflected light 14 is also small, making it difficult to detect small scratches 2b, etc.

In addition, since the light 6 emitted from the optical fiber 8 reaches not only nearby but also far, even when the detection head 12 is inserted into the cylindrical object 2, it is detected that there is a flaw 2b etc. on the inner surface 2a. Even if it is possible to do so, it is difficult to tell where the scratches are, and it is also difficult to tell how many scratches 2b etc. are there, so there is still room for improvement.

Therefore, the main object of the present invention is to provide an apparatus for inspecting the inner surface of a cylindrical object, which is further improved in the above points.

[Means to achieve the purpose]

In order to achieve the above object, the inner surface inspection device according to the present invention has a detection head as described above.
Use an optical fiber that can be inserted into the inner surface of the cylindrical object to be inspected, and in which the tips of the light-emitting and light-receiving optical fibers are directed outward with respect to the central axis of the detection head. , characterized in that a drive device is provided for moving at least one of the detection head and the cylindrical object and inserting the detection head into the inside of the cylindrical object.

[Effect]

When the above detection head is used, the light emitting and light receiving optical fibers are directed outward, so the light is concentrated in a narrow area near the detection head on the inner surface of the cylindrical object. By irradiating it, the inner surface state of a cylindrical object can be inspected by limiting the inspection area.

As a result, the amount of light irradiated to scratches and the like existing on the inner surface of the cylindrical object increases, and therefore the amount of light reflected therefrom also increases, making it easier to detect small scratches and the like.

By inserting such a detection head into the inside of the cylindrical object using the drive device, it is possible to move the inspection area on the inner surface of the cylindrical object, thereby covering a wide area of the inner surface of the cylindrical object. It can be inspected throughout.

Furthermore, in that case, the inspection can be carried out while limiting the inspection area as described above, so it becomes easier to see where on the inner surface of the cylindrical object there are scratches, etc., and how many there are.

〔Example〕

FIG. 1 is a schematic diagram showing an apparatus for inspecting the inner surface of a cylindrical object according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view showing an example of the detection head in FIG. 1. FIG. 3 is a front view of the detection head of FIG. 2. The same reference numerals are given to the same parts as those of the previous example shown in FIG. 8, etc., and the differences from the previous example will be mainly explained below.

The apparatus of this embodiment includes the following detection head 22, which corresponds to the detection head 12 described above.

That is, in this example, the detection heads 22 include a plurality of detection heads as described above (more specifically, six as shown in FIG. 3).
One end side of the light emitting optical fiber 8 and one end side of a plurality of light receiving optical fibers 10 (more specifically, three as shown in FIG. 3) are combined into one, and the above-mentioned It can be inserted into the inside of the cylindrical object 2. Each optical fiber 8
．． 10 has a diameter of 1 mm, for example, but it may be thinner or thicker than that, or a combination of thin and thick ones may be used.

Furthermore, in this detection head 22, as shown in FIG. (In Figure 2, to simplify the illustration,
(One optical fiber 8.10 is shown.)

This angle α is not limited to a specific value, but if it is too small, the inspection area (described later) will become too wide, and if it is too large, the amount of reflected light will increase even if there are no scratches, resulting in a decrease in the S/N ratio. , for example, preferably about 30 degrees.

More specifically, as shown in FIG. 3, a cap 23 having a triangular pyramid shape is provided at the tip of the detection head 22, and in this example, each of its three surfaces 23a to 23
At c, one light-receiving optical fiber 10 and two light-emitting optical fibers 8 sandwiching it are arranged as a set.

Further, in this embodiment, the detection head 22 is fixed,
By moving the cylindrical object 2 up and down in the direction of arrow A using the drive device 24, a detection head 22 is installed inside the cylindrical object 2.
I am trying to insert .

However, different from this, the cylindrical object 2 can be fixed by moving the detection head 22 while keeping the cylindrical object 2 fixed, or by moving both the detection head 22 and the cylindrical object 2 as necessary. The detection head 22 may be inserted inside.

When the detection head 22 as described above is used, each optical fiber 8.10 for light emission and light reception is aligned with the central axis 22a.
For example, as shown in FIG. 2, the light 6 is focused on a narrow area near the tip of the detection head 22 on the inner surface 2a of the cylindrical object 2. Thus, the inner surface condition of the cylindrical object 2 (ie, the presence of scratches, the presence of dust, etc.) can be inspected by limiting the inspection area.

As a result, the amount of light 6 irradiated to scratches, dirt, etc. existing on the inner surface 2a of the cylindrical object 2 increases, and therefore the amount of reflected light reflected from there also increases, allowing detection of small scratches, dirt, etc. It also becomes easier.

Moreover, such a detection head 22 is connected to, for example, a drive device 2.
4, the inspection area for the inner surface of the cylindrical object 2 can be moved, and the inner surface of the cylindrical object 2 can be inspected more specifically over a wide NMi. In this case, the detection head 22 shown in FIG. 3 can inspect the entire inner surface.

Furthermore, in that case, the inspection can be carried out while limiting the inspection area as described above, so it becomes easier to see where on the inner surface of the cylindrical object 2 there are scratches, etc., and how many there are.

Examples of test results using the apparatus of the above embodiment are shown in FIGS. 4 to 6.

In both figures, the detection head 22 as described above is connected to a cylindrical object 2.
This is the data on the amount of reflected light when it is inserted inside the tube and made one reciprocation. Outside the workpiece in the figure indicates the state where the detection head 22 has penetrated the cylindrical object 2 (workpiece), and the amount of reflected light at this time is due to noise. You can say it's level. Further, large peaks P at both ends in the figure indicate reflection from the end face of the cylindrical object 2.

Figure 4 shows the test results for the cylindrical object 2 that passed the visual inspection (that is, was determined to have no flaws), and there was no large peak in the amount of reflected light within the cylindrical object 2, indicating that the inner surface condition was It can be seen that it is in good condition.

Figure 5 shows the test results for another cylindrical object 2 that also passed the visual inspection, but there is a peak in the center of the cylindrical object 2, slightly closer to the entrance, and there is a peak that cannot be seen visually. I can see that there is a scar.

Figure 6 shows the inspection results for the cylindrical object 2 that failed the visual inspection, and there are two to three large peaks from the center of the cylindrical object 2 toward the entrance, and there are large scratches there. I understand that.

In this way, according to the apparatus of the above embodiment, it is possible to clearly detect even small scratches that cannot be detected by visual inspection, as well as their approximate location and number.

Therefore, the inner surface state of the cylindrical object 2 can be inspected very accurately. Furthermore, by analyzing such data, it becomes possible to detect the machining accuracy of the inner surface of the cylindrical object 2 and the wear and tear of the machining jig.

Incidentally, convex lens portions 8a and 10a may be provided at the tips of each of the light emitting and light receiving optical fibers 8.10 in the detection head 22, respectively, as in the embodiment shown in FIG. 7, for example. In this way, the optical fiber 8 for light projection
If we look at it, the emitted light can be focused by the action of the convex lens part 8a, and if we look at the light-receiving optical fiber 10, the reflected light can be collected by the action of the convex lens part 10a, so the S/N ratio is further improved. This further improves detection sensitivity.

In addition, in the detection head 22, an optical fiber 8 for light projection is connected to the detection head 22.
The arrangement of the light emitting optical fiber 8 and the light receiving optical fiber 10 is preferably set as in the above example in order to obtain a good S/N ratio, but the arrangement is not limited to this. For example, the light emitting optical fiber 8 and the light receiving optical fiber 8 The optical fibers 10 may be arranged in the opposite relationship to the above example, or may be arranged without being paired.

Furthermore, if the tip of the detection head 22 is divided into three sections and the optical fibers 8 and 10 are arranged therein as in the above example, the entire circumference of the inner surface of the cylindrical object 2 can be covered with a small number of optical fibers 8 and 10. Although it is possible to inspect uniformly, it is of course possible to use a larger number of sensors, and it is not necessary to rotate at least one of the cylindrical object 2 and the detection head 22, or to inspect the entire inner circumference of the cylindrical object 2. If there is no detection head 2
2 has an optical fiber 8 for transmitting light and an optical fiber 10 for receiving light.
It is only necessary that at least one of the and is arranged.

Further, the cylindrical object to be inspected by the inner surface inspection apparatus according to the present invention is not necessarily limited to a cylindrical object, but may be a rectangular cylindrical object. Further, the material is not limited to a cut product, but may be a resin molded product or the like.

〔Effect of the invention〕

As described above, according to the present invention, it is easier to inspect small scratches, dirt, etc. on the inner surface of a cylindrical object than with the prior art device, and how many such scratches, etc. are present on the inner surface? It becomes easier to understand if there are any. Therefore, the inner surface state of the cylindrical object can be inspected more accurately. This also makes it possible to detect the machining accuracy of the inner surface of the cylindrical object, the wear and tear of the machining jig, and the like.

In addition, by arranging the light emitting optical fiber and the light receiving optical fiber in the detection head as a pair, or by providing a convex lens section at their tips, the S/N ratio will be further improved and more accurate inspection will be possible. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an apparatus for inspecting the inner surface of a cylindrical object according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view showing an example of the detection head in FIG. 1. FIG. 3 is a front view of the detection head of FIG. 2. FIGS. 4 to 6 are diagrams each showing an example of the results of inspecting the inner surface of a cylindrical object using the apparatus of the embodiment. FIG. 7 is an enlarged sectional view showing another example of the detection head. FIG. 8 is a schematic diagram showing an example of an apparatus for inspecting the inner surface of a cylindrical object, which is the background of the present invention. FIG. 9 is an enlarged sectional view showing the detection head in FIG. 8 as viewed in the line 1=1 direction. FIG. 10 is a diagram schematically showing the state of light on the inner surface of a cylindrical object, in which (A) shows the case where there is no scratch, and (B) shows the case where there is a scratch. 2... Cylindrical object, 2a... Inner surface, 4... Light source, 6,
...Light, 8... Optical fiber for light projection, 8a... Convex lens portion, 10.0. Optical fiber for light reception, 10a...
Convex lens portion, 14...Reflected light, 16... Light receiver, 1
8... Comparison circuit, 22... Detection head, 24...
Drive device.

Claims (3)

[Claims] (1) A light source that emits light, one or more optical fibers for projecting light that guides the light from the light source and irradiates it onto the inner surface of the cylindrical object, and reflection from the inner surface of the cylindrical object. One or more light-receiving optical fibers that guide light, one end of the light-receiving optical fiber, and one end of the light-emitting optical fiber are integrated into one, and can be inserted into the cylindrical object. A detection head in which the tip of each optical fiber is directed outward with respect to the central axis of the detection head, and at least one of the detection head and the cylindrical object is moved to move the detection head to the A driving device inserted into the cylindrical object, a light receiver that receives the light guided by the light receiving optical fiber and converts it into an electrical signal, and an electrical signal from the light receiver or an electrical signal based thereon. An apparatus for inspecting the inner surface of a cylindrical object, comprising a comparison circuit for comparing with a predetermined reference value. (2) The inner surface inspection device for a cylindrical object according to claim 1, wherein in the detection head, one or more light emitting optical fibers and one or more light receiving optical fibers are arranged as a set. (3) The inner surface inspection device for a cylindrical object according to claim 1 or 2, wherein a convex lens portion is provided at the tip of each optical fiber for light projection and light reception in the detection head.