JPH0785005B2 - Method and device for inspecting inner diameter of pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and an apparatus for inspecting the inner diameter of a tubular body, and in particular, a tubular body made of a polymer material such as polyethylene or vinyl chloride in which an electric wire is laid. The present invention relates to a method and an apparatus for inspecting the inner diameter of a tube, which is effective for the inspection.

"Prior Art" Generally, in a pipe body (hereinafter referred to as a cable pipe body) in which a cable or the like is laid, it is very important to guarantee the inner diameter dimension. This is because unlike the tubular body through which the fluid is passed inside, if the inner diameter is smaller than a predetermined size, the sable cannot be passed through.

By the way, in general, in order to inspect the inner diameter of a pipe, a means for measuring the cross-sectional dimensions of both ends thereof is used. However,
Since this means cannot measure the central portion of the tube, it has a drawback that it cannot be applied to a tube whose inner diameter needs to be measured in the longitudinal direction like the cable tube.

Therefore, as a means for measuring the inner diameter of such a tube body for a cable, a means using an X-ray has been considered.
This means irradiates the tube with soft X-rays in the longitudinal direction and measures the inner diameter from the projected image.

[Problems to be Solved by the Invention] Meanwhile, the above-mentioned inner diameter inspecting means of the tubular body has a problem that the polymer material is cross-linked by the X-ray and may be deteriorated. In addition, accurate measurement cannot be performed unless a large number of X-ray irradiation directions are set. Therefore, there is a problem that a large number of expensive devices are required and the measurement cost is high. That is, considering the case of irradiating the X-ray X from two directions, a tubular body A having a circular cross section as shown in FIG. 14 and a tubular body B deformed to have a square cross section as shown in FIG. , An image a generated on the projection surface,
The images b are the same and cannot be distinguished. For this reason, it is necessary to irradiate X-rays from many directions, and therefore many expensive X-ray irradiation devices are required.

"Means for Solving Problems" The present invention has been made to solve the above problems, and in the first invention, an outer diameter made of a material attracted to a magnet in a tube of a tubular body. A plurality of mandrels different from each other are arranged, a magnet is arranged outside the tube at a position facing the insertion member, and the tube is moved in the axial direction with respect to the magnet. In the second invention, the insertion member made of a material attracted to the magnet is arranged in the tube of the tube body, and the magnet is arranged outside the tube body so as to face the insertion member. The magnet is provided with force measuring means for measuring a force applied in the axial direction of the tube body. In the third invention, a plurality of different outer diameters made of a material attracted to the magnet are provided in the tube of the tube body. Insert consisting of a mandrel Place the members,
While arranging the magnet at a position facing the insertion member outside the tube of the tube, arranging the coil outside the tube of the tube,
This coil is provided with an inductance measuring means for measuring the variation of the inductance of the coil.

[Operation] In the first aspect of the present invention, the insertion member made of a plurality of mandrels having different outer diameters, which is made of a material attracted to the magnet, is arranged in the tube of the tube body, and the insertion member is provided outside the tube body. Since the magnet is arranged at a position facing the insertion member and the tube body is moved in the axial direction with respect to the magnet, the insertion member attracted by the magnet is caught in the tube body. It is possible to inspect the inner diameter of the tubular body depending on whether or not the tubular body can be inspected. Further, in the second invention, an insertion member made of a material attracted to the magnet is arranged inside the tube of the tube body, and the magnet is arranged outside the tube body so as to face the insertion member. Since the force measuring means for measuring the force applied in the axial direction of the tubular body is provided, the portion of the tubular body located immediately before the magnet when a tension is applied to the magnet has a narrow inner diameter portion. Can be detected. Further, in the third invention, an insertion member made of a material attracted to a magnet and made of a plurality of mandrels having different outer diameters is arranged in the tube of the tube body and faces the insertion member outside the tube body. Since the magnet is arranged at the position, the coil is arranged outside the tube body, and the coil is provided with the inductance measuring means for measuring the fluctuation of the inductance of the coil. It can be detected that there is a portion having a narrow inner diameter in the portion of the pipe body located immediately before.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 13.

FIG. 1 shows the principle of a pipe inner diameter measuring apparatus used in the pipe inner diameter inspection method according to the present invention. This inner diameter inspection apparatus includes a mandrel (insertion member) 12 inside one end 11a of a pipe (tube body) 11 having a circular cross section. The mandrel 12 is made of iron, cobalt, nickel, an alloy containing them, a ferromagnetic material such as ferrite, or a permanent magnet. This mandrel 12
Is formed into a spherical shape, and the outer diameter thereof is set to the minimum value of the allowable inner diameter dimension of the pipe 11.

On the other hand, two magnets 13 and 13 are arranged at a position where the mandrel 12 is arranged near the outer peripheral surface of the pipe 11. The two magnets 13, 13 are located on opposite sides of the pipe 11 with the magnet 11 interposed therebetween. And these two magnets
13, 13 are made of permanent magnets or electromagnets, so that the polarities on the pipe 11 side are opposite to each other, that is, one magnet 13
If the polarity on the side of the pipe 11 is N, the pipe of the other magnet 13
It is arranged so that the polarity on the 11 side is S.

In order to measure the inner diameter of the pipe 11 using such a measuring device, first, the pipe 11 is moved in the axial direction. Then, the mandrel 12 is retained by the magnetic force of the magnets 13 and 13, and the inside of the pipe 11 is closed at the one end 11a.
Moves relatively to the other end 11b. Then, when the other end 11b of the pipe 11 passes in front of the magnets 13, 13, the mandrel 12 is discharged from the other end of the tubular body 11. In this way it is ensured that the inner diameter of the pipe 11 is greater than the outer diameter of the mandrel 12 over its length.

On the other hand, if the pipe 11 has a portion 11c with a narrow inner diameter as shown in FIG.
Is caught. Therefore, even if the other end 11b of the pipe 11 passes in front of the magnets 13, 13, the mandrel 12 is not discharged. From this, it is clear that the pipe 11 has a portion whose inner diameter is smaller than the outer diameter of the mandrel 12.

In this way, it is possible to determine whether the inner diameter of the pipe 11 is larger than the allowable minimum inner diameter.

As described above, in the method for inspecting the inner diameter of the pipe body, the mandrel 12 made of a ferromagnetic material is arranged in the pipe 11.
Magnets 13 and 13 are arranged outside the pipe 11 at positions facing the mandrel 12, and the pipe 11 is moved in the axial direction with respect to the magnets 13 and 13. The mandrel 12 attracted to 13,
Whether or not the inner diameter of the pipe 11 is larger than the outer diameter of the mandrel 12 can be determined by whether or not the pipe 11 is caught in the pipe 11, and therefore the inner diameter of the pipe 11 can be reliably and easily inspected.

Next, examples of the present invention will be described. In the following embodiments, components having the same configurations as those showing the above principle are designated by the same reference numerals, and the description thereof will be omitted. In addition, it goes without saying that the following examples also have the same high cost as the above examples.

FIG. 3 is a view showing a pipe inner diameter inspection device according to the present invention. In this tube inner diameter inspection device, the magnets 13,1
A tension meter (force measuring means) 21 for measuring the force applied in the axial direction of the pipe 11 is provided on the pipe 3. In such a structure, as shown in FIG. 4, when there is a portion 11c where the inner diameter of the pipe 11 is smaller than the outer diameter of the mandrel 12, the mandrel 12 is caught and moves. As a result, the magnet 1
A force is applied to 3,13 and this force is measured by the tensiometer 21,21. In this way, it is possible to detect that the portion located immediately before the magnets 13, 13 when the tension is applied to the magnets 13, 13 has the portion 11c with a narrow inner diameter.

FIG. 5 is a view showing another inner diameter inspection device for a tubular body according to the present invention. A coil 31 is provided in the inner diameter inspection device for the pipe body. The coil 31 is located on the front side in the traveling direction of the pipe 11 with respect to the magnets 13, 13, and is arranged so as to be located near the outer peripheral surface of the pipe 11 when the pipe 11 moves forward. There is. In this coil 31,
An inductance measuring device (inductance measuring means) 32 for measuring the inductance of a coil such as a bridge is connected. In such a structure, as shown in FIG. 6, when there is a portion 11c where the inner diameter of the pipe 11 is smaller than the outer diameter of the mandrel 12, the mandrel 12 is caught and moves forward. The mandrel 12 is the coil
When passing just before 31, the inductance of the coil 31 changes, and the inductance measuring device 32 detects this change. In this way, it is possible to detect that the portion located immediately before the coil 31 has the portion 11c having a narrow inner diameter when the inductance changes.

FIG. 7 is a view showing another inner diameter inspection device for a tubular body according to the present invention. In this inner diameter inspection device for a pipe body, a large diameter mandrel (insertion member) 41 and a small diameter mandrel (insertion member) 42 having different outer diameters are inserted into the pipe 11, and the large diameter mandrel 41 advances in the pipe 11. The small-diameter mandrel 42 is disposed on the front side in the direction of travel and on the rear side in the traveling direction of the pipe 11. Then, outside the pipe 11,
At the positions where the large diameter mandrel 41 and the small diameter mandrel 42 are arranged, front magnets (magnets) 43, 43,
Rear magnets (magnets) 44, 44 are arranged. In such a structure, the pipe 11 is moved in the axial direction, and the inner diameter of the mandrel is determined depending on which mandrel is caught. That is, as shown in FIG. 8, when the large diameter mandrel 41 passes through the pipe 11 without being caught,
It is detected that the minimum inner diameter of the pipe 11 is larger than the outer diameter of the large diameter mandrel 41. Further, as shown in FIG. 9, when the large diameter mandrel 41 is caught and the small diameter mandrel 42 passes without being caught, the pipe
It is detected that the minimum inner diameter of 11 is smaller than the outer diameter of the large diameter mandrel 41 and larger than the outer diameter of the small diameter mandrel 42. Further, as shown in FIG. 10, when the small diameter mandrel 42 is caught, it is detected that the minimum inner diameter of the pipe 11 is smaller than the outer diameter of the small diameter mandrel 42. In this way, the minimum inner diameter of the pipe 11 can be determined within a certain range.

In addition, in the above embodiment, the mandrel is formed in a spherical shape, but the mandrel is not limited to this, and as shown in FIG. 11, a mandrel (insertion member) 51 formed in a cylindrical shape may be used. As shown in FIG. 12, a mandrel (insertion member) 52 may be formed in a warhead shape whose one end is reduced in diameter as it is separated from the central blow, and as shown in FIG. Mandrel (insertion member) formed so that its diameter decreases as it moves away from its central portion
53 is also acceptable.

Further, although one or two mandrels are provided in the above embodiment, the number of mandrels is not limited to this, and three or more mandrels may be provided.

[Advantages of the Invention] As described above, according to the present invention, in the first invention, the insertion member made of a plurality of mandrels having different outer diameters, which is made of the material attracted to the magnet, is provided in the tube of the tube body. The magnet is arranged outside the tube of the tube so as to face the insertion member, and the tube is moved in the axial direction with respect to the magnet. Therefore, the magnet is attracted to the magnet. In addition, the inner diameter of the tubular body can be determined by whether or not any one of the mandrels of the insertion member is caught in the tubular body, and thus the tubular body can be reliably and easily inspected. Also,
In the second invention, an insertion member made of a material that is attracted to a magnet is arranged in the tube of the tube body, and a magnet is arranged outside the tube body so as to face the insertion member. Since the force measuring means for measuring the force applied in the axial direction of the magnet is provided, it is detected that the portion of the tubular body located immediately before the magnet has a narrow inner diameter when tension is applied to the magnet. The effect of being able to do is obtained. Further, in the third invention, an insertion member made of a material attracted to a magnet and made of a plurality of mandrels having different outer diameters is arranged in the tube of the tube body and faces the insertion member outside the tube body. Since the magnet is arranged at the position, the coil is arranged outside the tube body, and the coil is provided with the inductance measuring means for measuring the fluctuation of the inductance of the coil. It is possible to obtain the effect that it is possible to detect that there is a portion having a narrow inner diameter in the portion of the pipe body located immediately before.

[Brief description of drawings]

1 and 2 are diagrams showing the principle of the present invention,
FIG. 1 is a sectional view thereof, FIG. 2 is a sectional view showing a state in which a mandrel is caught in a portion having a small inner diameter, and FIGS. 3 and 4 are views showing an embodiment of the present invention. FIG. 4 is a sectional view showing the same, FIG. 4 is a sectional view showing a state in which a mandrel is hooked on a portion having a small inner diameter, and FIGS. 5 and 6 are diagrams showing still another embodiment. Its sectional view, FIG. 6 is a sectional view showing a state in which the mandrel is hooked on a portion having a small inner diameter, and FIGS. 7 to 10 are diagrams showing other embodiments. FIG. 7 is a sectional view thereof. FIG. 8 is a sectional view showing a state in which both the large diameter mandrel and the small diameter mandrel pass through the pipe, and FIG. 9 is a sectional view showing a state in which the large diameter mandrel is caught in the pipe and the small diameter mandrel passes through the pipe. Figure 10 shows that both the large diameter mandrel and the small diameter mandrel are Sectional view showing a state of being caught in the pipe, FIGS. 11 to 13 are sectional views showing a mandrel having another shape, and FIGS. 14 and 15 are views showing a conventional method for inspecting the inner diameter of a tubular body. Is. 11 …… Pipe (tubular body), 12 …… Mandrel (insertion member), 13 …… Magnet, 21 …… Tensometer (force measuring means), 31…
... coil, 32 ... inductance measuring device (inductance measuring means), 41 ... large diameter mandrel (insertion member),
42 …… Small diameter mandrel (insertion member), 43 …… Front magnet (magnet), 44 …… Rear magnet (magnet), 51 …… Mandrel (insertion member), 52 …… Mandrel (insertion member), 53 ……
Mandrel (insertion member).

Claims (5)

[Claims] 1. An insertion member made of a material that is attracted to a magnet is arranged inside a tube of a tube, and a magnet is arranged outside the tube at a position facing the insertion member, and the magnet is arranged with respect to the magnet. A method of inspecting an inner diameter of a tubular body for moving the tubular body in an axial direction thereof, wherein the insertion member is composed of a plurality of mandrels having different outer diameters, and the outer diameters of these mandrels are sequentially increased in accordance with the traveling method of the tubular body. A method for inspecting the inner diameter of a pipe, which is characterized in that 2. An insertion member made of a material that is attracted to a magnet is arranged inside the tube body, and a magnet is arranged outside the tube body at a position facing the insertion member. An inner diameter inspection device for a tubular body, comprising force measuring means for measuring a force applied in the axial direction. 3. The inner diameter inspection device for a pipe according to claim 2, wherein the insertion member is formed in a spherical shape, a cylindrical shape, or a warhead shape. 4. The insert member comprises a plurality of mandrels having different outer diameters, and these mandrels are arranged such that the outer diameters thereof successively increase in the traveling direction of the tubular body. The inner diameter inspection device for a pipe according to the second aspect. 5. An insertion member made of a material attracted to a magnet is arranged inside the pipe body, a magnet is arranged outside the pipe body at a position facing the insertion member, and the outside pipe body of the pipe body is arranged. A coil inner diameter inspecting device, in which a coil is arranged, and the coil is provided with an inductance measuring unit for measuring a variation in the inductance of the coil, wherein the insertion member is composed of a plurality of mandrels having different outer diameters. An inner diameter inspection device for a pipe body, wherein the mandrel is arranged such that its outer diameter is gradually increased in the traveling direction of the pipe body.