JP2009058547A - Optical fiber cooling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber cooling apparatus in which a high power laser is stably transmitted for a long time without being influenced by environment by cooling the optical fiber. <P>SOLUTION: The optical fiber cooling apparatus is provided with: a laser oscillator 10 which oscillates the laser; an optical fiber 11 which transmits the laser; an outer jacket 14 having a cylindrical form to house the optical fiber; and a cooling means which supplies a cooling medium into the outer jacket to cool the optical fiber within a predetermined temperature range for suppressing the expansion or contraction of the optical fiber due to the change in the temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber cooling device.

  Conventionally, a method of reducing residual stress on the inner surface side of the pipe by heating or melting the outer surface of the stainless steel pipe by laser heating is known. However, in this construction method, an area exposed to the sensitization temperature is generated in the vicinity of the heating area, which may adversely affect the material. Moreover, an oxide scale is formed on the heating surface, and it becomes necessary to remove the oxide scale. An example of a method for reducing the residual stress as described above is disclosed in Patent Document 1 below.

  For this reason, as an alternative to the conventional method for reducing residual stress as described above, a laser oscillated by a laser oscillator 60 as shown in FIG. However, there is known a residual stress improving method using a laser that irradiates the laser while heating the outer surface of the pipe 63 with the laser to reduce the residual stress on the inner surface side of the pipe 63.

JP-A-61-96025

  However, in the residual stress improvement method using the laser described above, the laser is transmitted from the laser oscillator to the construction part by an optical fiber. However, in a nuclear power plant, for example, as shown in FIG. It is necessary to transmit the laser using the optical fiber 61 over a long distance to the construction section 62 in the building 64.

  In addition, by laying the optical fiber 61 outside the building 64, the temperature of the optical fiber 61 may be heated beyond an allowable range due to the influence of sunlight and the outside air temperature. In this case, an unnecessary force is applied to the glass portion due to a difference in elongation due to heat between the glass portion and the resin portion of the optical fiber 61, which may affect the characteristics of the laser to be transmitted.

  In view of the above, the present invention provides an optical fiber cooling device capable of stably transmitting a high-power laser for a long time without being affected by the surrounding environment by cooling the optical fiber. With the goal.

An optical fiber cooling device according to the first invention for solving the above-mentioned problems is as follows.
A laser oscillator that oscillates a laser;
An optical fiber for transmitting the laser;
A cylindrical outer tube for housing the optical fiber;
And a cooling means for supplying a cooling medium into the outer cylinder and cooling the optical fiber in a predetermined temperature range in order to suppress expansion or contraction due to a temperature change of the optical fiber.

  Therefore, by cooling the optical fiber that transmits the laser, it is possible to prevent the temperature increase of the optical fiber due to transmission loss, and it is possible to stably use a high-power laser for a long time. Furthermore, by cooling the optical fiber, a high-power laser can be stably transmitted for a long time without being affected by the surrounding environment.

An optical fiber cooling device according to a second invention for solving the above-mentioned problems is the optical fiber cooling device according to the first invention, wherein the laser oscillator is installed outdoors, and the outer tube is installed outside the optical fiber. It is installed only in the part laid in.
Therefore, by installing the laser oscillator outdoors, it is possible to perform construction by a residual stress improving method using a laser even in a narrow space. Further, by setting the cooling range to only the outdoor laying part having a large environmental fluctuation, it is possible to simplify the equipment and reduce the work amount. Furthermore, in a nuclear power plant, work in the radiation control area is reduced, which can contribute to reduction of exposure and waste.

An optical fiber cooling device according to a third aspect of the present invention for solving the above-mentioned problems is characterized in that, in the optical fiber cooling device according to the second aspect of the invention, the outer cylinder is subjected to reflection processing on the surface.
Therefore, since sunlight is reflected, it is possible to prevent an increase in temperature due to sunlight of the optical fiber.

  An optical fiber cooling device according to a fourth aspect of the present invention for solving the above-described problems is an optical fiber cooling device according to any one of the first to third aspects of the invention, wherein the optical fiber is wound up appropriately. An optical fiber drum having a length; and an optical fiber drum cooling means for cooling in a predetermined temperature range in order to suppress expansion or contraction due to a temperature change of the optical fiber wound around the optical fiber drum, Is constituted by a plurality of small outer cylinders, and the cooling means is installed for each of the small outer cylinders.

  Therefore, in the local construction, the distance from the installation location of the laser oscillator to the construction part is different, but the optical fiber can be divided into the laying part and the part wound around the optical fiber drum, and the cooling means is divided into two parts. Therefore, the cooling means can be installed appropriately and flexibly according to the plant.

An optical fiber cooling device according to a fifth aspect of the present invention for solving the above-described problems is the optical fiber cooling device according to any one of the first to fourth aspects of the invention, wherein the outer tube is half-cracked. It is characterized by that.
Therefore, the outer cylinder can be easily installed after laying the optical fiber, and the entire optical fiber cooling device can be installed after laying the optical fiber. Therefore, a plurality of installation routes need to be changed. Appropriate and flexible response to the plant.

An optical fiber cooling device according to a sixth invention for solving the above-mentioned problems is the optical fiber cooling device according to the fifth invention, wherein the outer cylinder holds the optical fiber at the center inside the outer cylinder. A jig is provided.
Therefore, since the optical fiber can be held in the middle of the air inside the outer cylinder, the optical fiber can be directly and uniformly cooled, and the high output laser is not affected by the surrounding environment. Can be stably transmitted for a long time.

An optical fiber cooling device according to a seventh invention for solving the above-mentioned problems is the optical fiber cooling device according to any one of the first to sixth inventions, wherein the outer cylinder has an axial end portion. And a cylindrical jacket whose inner surface is a perforated plate.
Therefore, the cooling efficiency can be improved by cooling with the collision jet of the cooling medium also at the inlet portion of the optical fiber at the end of the outer cylinder where the temperature rises more easily than other portions due to axial heat conduction or the like. it can.

An optical fiber cooling device according to an eighth invention for solving the above-mentioned problems is the optical fiber cooling device according to the seventh invention, wherein the jacket has a pitch of holes formed in the porous plate, It becomes smaller as it goes to the end of the cylinder in the axial direction, and it becomes larger as it goes inward in the axial direction of the outer cylinder.
Therefore, it is possible to set the cooling efficiency in accordance with the heat load distribution by changing the pitch of the holes that generate the collision jet, so that the cooling efficiency is further improved at the optical fiber inlet at the end of the outer cylinder. Can be improved.

An optical fiber cooling device according to a ninth invention for solving the above-described problems is the optical fiber cooling device according to the seventh invention or the eighth invention, wherein the jacket has a thickness of a wall portion in a radial direction. The outer cylinder is thicker as it goes to the end in the axial direction, and it is thinner as it goes to the inner side in the axial direction of the outer cylinder.
Accordingly, by changing the collision jet flow distance, it is possible to set the cooling efficiency desired to correspond to the heat load distribution, so that the cooling efficiency can be further improved. Furthermore, since the flow path area increases as the flow rate from the nozzle hole increases, the pressure loss of the cooling medium can be reduced.

An optical fiber cooling device according to a tenth aspect of the present invention for solving the above problem is the optical fiber cooling device according to any one of the seventh to eighth aspects of the invention, wherein the shaft of the outer cylinder of the perforated plate is used. A taper portion is formed at an inner end portion in the direction.
Therefore, the pressure loss due to the rapid expansion of the opening can be minimized by forming the tapered portion at the end of the perforated plate.

  ADVANTAGE OF THE INVENTION According to this invention, the optical fiber cooling device which can transmit a high output laser stably for a long time without being influenced by the surrounding environment by cooling an optical fiber is realizable.

  Various embodiments of an optical fiber cooling device according to the present invention will be described with reference to FIGS. 1 shows a configuration example of the optical fiber cooling device according to the first embodiment of the present invention, and FIG. 2 shows a configuration example of the optical fiber cooling device according to the second embodiment of the present invention. FIG. 3 is a diagram showing a configuration example of an optical fiber cooling device according to the third embodiment of the present invention, and FIG. 4 is an outer cylinder in the optical fiber cooling device according to the fourth and fifth embodiments of the present invention. FIG. 5 is a diagram showing the structure of a jig in an optical fiber cooling apparatus according to the fifth embodiment of the present invention, and FIG. 6 is an optical fiber cooling according to the sixth embodiment of the present invention. FIG. 7 is a diagram showing the structure of a jacket in the apparatus, FIG. 7 is a diagram showing the structure of the jacket in the optical fiber cooling apparatus according to the seventh embodiment of the present invention, and FIG. 8 is the light according to the eighth embodiment of the present invention. Figure 9 shows the jacket structure in the fiber cooling device. Is a diagram showing the structure of the jacket in the optical fiber cooling device according to light of the ninth embodiment.

[First Embodiment]
Hereinafter, a first embodiment of an optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to this embodiment is characterized in that, in a stress improvement method using a laser that transmits an optical fiber from a laser oscillator to a construction part, the optical fiber is cooled by the cooling device.

  Next, a configuration example of the optical fiber cooling device according to the present embodiment will be described. As shown in FIG. 1, the laser oscillated by the laser oscillator 10 is transmitted via the optical fiber 11 to the construction unit 13 installed on the construction object 12 in the building 18. Then, a residual stress improving method using a laser is applied to the work object 12 by the laser transmitted by the optical fiber 11. The optical fiber 11 is provided with a cylindrical outer cylinder 14 that covers the optical fiber 11. A refrigerator 15 for supplying a cooled cooling medium into the outer cylinder 14 is installed near the center of the outer cylinder 14. A dehumidifier 16 is installed in the refrigerator 15 in order to prevent condensation in the outer cylinder 14.

  Further, a blower 17 that discharges the cooling medium from the inside of the outer cylinder 14 is installed in the vicinity of both ends of the outer cylinder 14. That is, the cooling medium sucked into the dehumidifier 16 is dehumidified and then cooled in the refrigerator 15, and the cooled cooling medium is supplied into the outer cylinder 14 to cool the optical fiber 11 and cool the optical fiber 11. The cooled cooling medium is discharged from the outer cylinder 14 by the blower 17.

  Moreover, the pressure loss of a cooling medium can be reduced by installing the refrigerator 15 in the central part vicinity of the outer cylinder 14, and installing the air blower 17 in the vicinity of the both ends of the outer cylinder 14. Thereby, since the diameter of the outer cylinder 14 can be made small, it can respond flexibly to the bending condition of the optical fiber 11. In the present embodiment, the cooling medium is air, and the air sucked from the atmosphere is exhausted again to the atmosphere. However, a gas other than air or a liquid such as water is used as the cooling medium, and the sucked gas is air. It is also possible to circulate again without exhausting into it.

  Furthermore, the cooling temperature by the optical fiber cooling device according to the present embodiment is set so that the temperature of the optical fiber 11 falls within a range of about 0 ° C. to 40 ° C. When the temperature of the optical fiber 11 is too high, this is due to the characteristics of the transmitted laser due to deformation caused by a difference in expansion coefficient due to thermal expansion between the glass portion of the optical fiber 11 and the coating portion of the optical fiber 11. Naturally, there is a possibility of an influence, but even when the temperature is too low, the temperature is transmitted due to deformation caused by a difference in shrinkage between the glass portion of the optical fiber 11 and the coating portion of the optical fiber 11. This is because there is a possibility of affecting the characteristics of the laser, and the conventional optical fiber 11 may not be simply cooled extremely.

  As described above, according to the present embodiment, by cooling the optical fiber 11 that transmits the laser, it becomes possible to prevent the temperature of the optical fiber 11 from increasing due to transmission loss, and to stabilize a high-power laser for a long time. Can be used. Furthermore, by cooling the optical fiber 11, a high-power laser can be stably transmitted for a long time without being affected by the surrounding environment.

[Second Embodiment]
Hereinafter, a second embodiment of the optical fiber cooling apparatus according to the present invention will be described. The optical fiber cooling device according to the present embodiment is a method for stress improvement using a laser that transmits an optical fiber from a laser oscillator to a construction site using an optical fiber. The laser oscillator is installed outdoors, and the cooling range of the optical fiber is outdoors. It is characterized only by the laying part. Moreover, in order to prevent the optical fiber from being heated by sunlight, the solar light is reflected.

  Next, a configuration example of the optical fiber cooling device according to the present embodiment will be described. As shown in FIG. 2, in this embodiment, the laser oscillator 10 is installed outside the building 18. The laser oscillated by the laser oscillator 10 is transmitted to the construction section 13 installed on the construction object 12 through the optical fiber 11. Then, a residual stress improving method using a laser is applied to the work object 12 by the laser transmitted by the optical fiber 11. The optical fiber 11 is provided with a cylindrical outer cylinder 14 that covers the optical fiber 11. In addition, in order to prevent the temperature rise of the optical fiber 11 due to sunlight by reflecting sunlight, the outer cylinder 14 is subjected to reflection processing with an aluminum foil or the like on the surface of the outer cylinder 14. In the present embodiment, the outer cylinder 14 is installed only in the laying portion 19 laid outside from the laser oscillator 10 to the building 18.

  A refrigerator 15 for supplying a cooled cooling medium into the outer cylinder 14 is installed near the center of the outer cylinder 14. In the refrigerator 15, a dehumidifier 16 is installed to prevent condensation in the outer cylinder 14. Further, a blower 17 that discharges the cooling medium from the inside of the outer cylinder 14 is installed in the vicinity of both ends of the outer cylinder 14. That is, the cooling medium sucked into the dehumidifier 16 is dehumidified and then cooled in the refrigerator 15, and the cooled cooling medium is supplied into the outer cylinder 14 to cool the optical fiber 11 and cool the optical fiber 11. The cooled cooling medium is discharged from the outer cylinder 14 by the blower 17.

  Moreover, the pressure loss of a cooling medium can be reduced by installing the refrigerator 15 in the central part vicinity of the outer cylinder 14, and installing the air blower 17 in the vicinity of the both ends of the outer cylinder 14. Thereby, since the diameter of the outer cylinder 14 can be made small, it can respond flexibly to the bending condition of the optical fiber 11. In this embodiment, the cooling medium is air, and the air sucked from the atmosphere is exhausted again to the atmosphere. However, a gas other than air is used as the cooling medium, and the sucked gas is not exhausted to the atmosphere. It is also possible to configure to circulate again.

  Furthermore, the cooling temperature by the optical fiber cooling device according to the present embodiment is set so that the temperature of the optical fiber 11 falls within a range of about 0 ° C. to 40 ° C. When the temperature of the optical fiber 11 is too high, this is due to the characteristics of the transmitted laser due to deformation caused by a difference in expansion coefficient due to thermal expansion between the glass portion of the optical fiber 11 and the coating portion of the optical fiber 11. Naturally, there is a possibility of an influence, but even when the temperature is too low, the temperature is transmitted due to deformation caused by a difference in shrinkage between the glass portion of the optical fiber 11 and the coating portion of the optical fiber 11. This is because there is a possibility of affecting the characteristics of the laser, and the conventional optical fiber 11 may not be simply cooled extremely.

  As described above, according to the present embodiment, in addition to the effect of the optical fiber cooling device in the first embodiment, the laser oscillator 10 is installed outdoors, so that the residual stress improvement method using a laser can be achieved even in a narrow space. Construction is possible. Further, by using only the outdoor laying portion 19 having a large environmental fluctuation as the cooling range, it is possible to simplify the equipment and reduce the amount of work. Furthermore, in a nuclear power plant, work in the radiation control area is reduced, which can contribute to reduction of exposure and waste.

[Third Embodiment]
Hereinafter, a third embodiment of the optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to the present embodiment separately cools the optical fiber drum and the optical fiber laying portion in the stress improvement method using the laser that transmits from the laser oscillator to the construction portion using the optical fiber, The laying portion of the optical fiber is cooled by being divided into a plurality of regions.

  Next, a configuration example of the optical fiber cooling device according to the present embodiment will be described. As shown in FIG. 3, in this embodiment, the laser oscillator 10 is installed outside the building 18. The laser oscillated by the laser oscillator 10 is transmitted to the construction section 13 installed on the construction object 12 through the optical fiber 11. The optical fiber 11 is wound around the optical fiber drum 20 so as to have an appropriate length. Then, a residual stress improving method using a laser is applied to the work object 12 by the laser transmitted by the optical fiber 11.

  The optical fiber 11 is provided with a cylindrical outer cylinder 14 that covers the optical fiber 11. In the present embodiment, the outer cylinder 14 is installed only in the laying portion 19 laid outside from the laser oscillator 10 to the building 18. In addition, in order to reflect sunlight and prevent the temperature rise of the optical fiber 11 due to sunlight, the outer cylinder 14 is subjected to reflection processing with an aluminum foil or the like on the surface of the outer cylinder 14.

  In the present embodiment, the outer cylinder 14 is composed of a plurality of small outer cylinders 14 s for cooling the laying portion 19 of the optical fiber 11 by dividing it into a plurality of regions. A refrigerator 15 for supplying a cooled cooling medium into the small outer cylinder 14s is installed near the center of the small outer cylinder 14s. The refrigerator 15 is provided with a dehumidifier 16 in order to prevent condensation in the small outer cylinder 14s.

  A blower 17 that discharges the cooling medium from the small outer cylinder 14s is installed in the vicinity of both ends of the small outer cylinder 14s. That is, the cooling medium sucked into the dehumidifier 16 is dehumidified and then cooled in the refrigerator 16, and the cooled cooling medium is supplied into the small outer cylinder 14 s to cool the optical fiber 11. The cooled cooling medium is discharged from the small outer cylinder 14 s by the blower 17.

  Moreover, the pressure loss of a cooling medium can be reduced by installing the refrigerator 15 in the center part vicinity of the small outer cylinder 14s, and installing the air blower 17 in the vicinity of the both ends of the small outer cylinder 14s. Thereby, since the diameter of the small outer cylinder 14s can be reduced, it is possible to flexibly cope with the bending state of the optical fiber 11. In this embodiment, the cooling medium is air, and the air sucked from the atmosphere is exhausted again to the atmosphere. However, a gas other than air is used as the cooling medium, and the sucked gas is not exhausted to the atmosphere. It is also possible to configure to circulate again.

  A cover 21 that covers the optical fiber drum 20 is attached to the optical fiber drum 20. A refrigerator 22 is installed in the cover 21, and the cooling medium supplied from the refrigerator 22 is circulated through the cover 21 by the cooler 23. Thereby, the optical fiber 11 wound around the optical fiber drum 20 can be cooled.

  Furthermore, the cooling temperature by the optical fiber cooling device according to the present embodiment is set so that the temperature of the optical fiber 11 falls within a range of about 0 ° C. to 40 ° C. When the temperature of the optical fiber 11 is too high, this affects the characteristics of the transmitted laser due to deformation caused by a difference in expansion coefficient due to thermal expansion between the optical fiber 11 and the coating portion of the optical fiber 11. Naturally, there is a possibility that even if the temperature is too low, the characteristics of the transmitted laser are affected by deformation caused by the difference in shrinkage between the optical fiber 11 and the coating portion of the optical fiber 11. In other words, the conventional optical fiber 11 may not be simply cooled extremely.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling device in the first and second embodiments, the distance from the installation location of the laser oscillator 10 to the construction portion 13 is different in the field work. The optical fiber 11 can be divided into the laying part 19 and the part wound around the optical fiber drum 20, and the refrigerators 15, 22 and the blower 17 can be separated into two parts. Accordingly, the refrigerators 15 and 22 and the blower 17 can be installed appropriately and flexibly.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the optical fiber cooling device according to the present invention will be described. In the optical fiber cooling device according to the first to third embodiments, the optical fiber cooling device according to the present embodiment is further an outer tube that can cover the structure of the outer tube with a half-cracked shape. And

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIG. 4, the main body portion of the outer cylinder 14 is formed by a bellows cooling pipe 30 that is a bellows-like cylinder. The optical fiber 11 is accommodated in the bellows cooling pipe 30. Since the bellows cooling pipe 30 has a flexible bellows shape, it can flexibly cope with the bending state of the optical fiber 11. Further, the bellows cooling pipe 30 has a half crack shape, and a fastener 32 is attached to the half crack portion 31.

  The outer side of the bellows cooling pipe 30 is covered with a dew condensation preventing heat insulating material 33 in order to prevent the condensation on the bellows cooling pipe 30. The heat insulating material 33 for preventing condensation has a half crack shape corresponding to the half crack portion 31 of the bellows cooling pipe 30, and a magic tape (registered trademark) 34 is attached to the half crack portion 31. . For this reason, when the optical fiber 11 is housed in the bellows cooling pipe 30, it can be easily housed simply by removing the magic tape 34 of the heat insulating material 33 for preventing condensation and opening the fastener 32 of the bellows cooling pipe 30. .

  In addition, a fastener 35 is attached to the end of the bellows cooling pipe 30 at the end in the axial direction of the bellows cooling pipe 30 constituting the outer cylinder 14 and the heat insulating material 33 for preventing condensation. In addition, a magic tape is attached to the end of the heat insulating material 30 for preventing condensation. For this reason, when connecting a plurality of outer cylinders 14, the outer cylinders 14 can be easily connected by simply closing the fasteners 35 of the bellows cooling pipe 30 and attaching the magic tape 36 of the heat insulating material 33 for preventing condensation. be able to.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling device in the first to third embodiments, the outer tube 14 can be easily installed after the optical fiber 11 is laid, Since the entire optical fiber cooling device can be installed after the optical fiber 11 is laid, it is possible to appropriately and flexibly cope with a plurality of different plants that require a change in the laying route.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to the present embodiment is characterized in that in the optical fiber cooling device according to the fourth embodiment, a jig for holding the optical fiber is further provided at substantially the center inside the outer cylinder.

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIGS. 4 and 5A, a jig 40 that supports the optical fiber 11 is installed in the bellows cooling pipe 30. The optical fiber 11 is supported by a cylindrical portion 40 a inside the jig 40. The jig 40 has a structure that does not hinder the flow of the cooling medium. Then, as shown in FIG. 5B, when the optical fiber 11 is stored, the jig is also cracked corresponding to the half cracked portion 31 of the bellows cooling pipe 30 and the anti-condensation heat insulating material 33. Yes. For this reason, it becomes possible to easily hold the optical fiber 11 at the center of the bellows cooling pipe 30.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling device according to the fourth embodiment, the optical fiber 11 can be held in the substantially central air inside the outer cylinder 14, The optical fiber 11 can be directly and uniformly cooled, and a high-power laser can be stably transmitted for a long time without being affected by the surrounding environment.

[Sixth Embodiment]
Hereinafter, a sixth embodiment of the optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to the present embodiment is an optical fiber cooling device according to any of the first to fifth embodiments. Since the temperature rises more easily than in the portion, a jacket is provided at the entrance of the optical fiber, and the cooling efficiency is improved by cooling with a collision jet of a cooling medium.

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIG. 6, a cylindrical jacket 51 whose inner surface is a porous plate 50 is installed at the inlet portion 14 a of the optical fiber 11 at the end of the outer cylinder 14. The jacket 51 is provided with a refrigerator (not shown), a cooling medium is supplied into the jacket 51, and the cooling medium is ejected from the perforated plate 50.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling devices according to the first to fifth embodiments, the temperature rises more easily than other portions due to axial heat conduction or the like. The cooling efficiency can also be improved by cooling the inlet 14a of the optical fiber 11 at the end of the tube 14 by the collision jet of the cooling medium.

[Seventh Embodiment]
Hereinafter, a seventh embodiment of the optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to the present embodiment is the optical fiber cooling device according to the first to fifth embodiments. In the inlet portion of the optical fiber of the outer cylinder, due to the heat conduction in the axial direction or the like, Since the temperature rises more easily, a jacket is provided at the inlet and the cooling efficiency is improved by cooling with a collision jet of a cooling medium. At this time, the pitch of the holes in the perforated plate is changed to form a hole arrangement that matches the amount of heat removed in the axial direction.

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIG. 7, a cylindrical jacket 51 whose inner surface is a porous plate 50 is installed at the inlet portion 14 a of the optical fiber 11 at the end of the outer cylinder 14. The jacket 51 is provided with a refrigerator (not shown), a cooling medium is supplied into the jacket 51, and the cooling medium is ejected from the perforated plate 50. The pitch of the holes in the portion of the perforated plate 50 indicated by A becomes smaller as it goes to the end of the outer cylinder 14, and becomes larger as it goes inward in the axial direction of the outer cylinder 14.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling devices according to the first to fifth embodiments, the pitch of the holes that generate the collision jet is changed, so that the heat load distribution is changed. Therefore, the cooling efficiency can be further improved at the inlet portion 14a of the optical fiber 11 at the end of the outer cylinder 14.

[Eighth Embodiment]
Hereinafter, an eighth embodiment of the optical fiber cooling device according to the present invention will be described. The optical fiber cooling device according to the present embodiment is the optical fiber cooling device according to the first to fifth embodiments. In the inlet portion of the optical fiber of the outer cylinder, due to the heat conduction in the axial direction or the like, Since the temperature rises more easily, a jacket is provided at the inlet and the cooling efficiency is improved by cooling with a collision jet of a cooling medium. At this time, the perforated plate is arranged in a tapered shape, and the distance from the nozzle hole is changed to perform cooling so as to meet the heat removal amount in the axial direction.

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIG. 8, a cylindrical jacket 51 whose inner surface is a perforated plate 50 is installed at the inlet 14 a at the end of the outer cylinder 14. The jacket 51 is provided with a refrigerator (not shown), a cooling medium is supplied into the jacket 51, and the cooling medium is ejected from the perforated plate 50.

  The jacket 51 is formed so that a portion indicated by B is tapered, and the thickness of the jacket 51 becomes thicker toward the end of the outer cylinder 14 and goes inward in the axial direction of the outer cylinder 14. It gets thinner. For this reason, the conduction heat of the jacket 51 becomes larger as it goes to the end of the outer cylinder 14, and becomes smaller as it goes inward in the axial direction of the outer cylinder 14. Further, the amount of cooling heat of the jacket 51 increases as it goes toward the end of the outer cylinder 14, and decreases as it goes inward in the axial direction of the outer cylinder 14.

  As described above, according to the present embodiment, in addition to the effects provided by the optical fiber cooling devices according to the first to fifth embodiments, the cooling efficiency desired for the heat load distribution is set by changing the collision jet distance. Therefore, the cooling efficiency can be further improved. Furthermore, since the flow path area increases with an increase in the flow rate from the nozzle hole, the pressure loss of the cooling medium can be reduced as compared with the structure of the outer cylinder according to the sixth and seventh embodiments.

[Ninth Embodiment]
The ninth embodiment of the optical fiber cooling device according to the present invention will be described below. The optical fiber cooling device according to the present embodiment is the same as the optical fiber cooling device according to the sixth and seventh embodiments. The power loss of the blower is reduced by minimizing the pressure loss.

  Next, the structure of the outer cylinder of the optical fiber cooling device according to this embodiment will be described. As shown in FIG. 9, a cylindrical jacket 51 whose inner surface is a perforated plate 50 is installed at the inlet 14 a at the end of the outer cylinder 14. The jacket 51 is provided with a refrigerator (not shown), a cooling medium is supplied into the jacket 51, and the cooling medium is ejected from the perforated plate 50. And a jacket forms a taper part in the axial direction inner side part of the perforated panel 51 edge part shown by C. As shown in FIG.

  As described above, according to the present embodiment, in addition to the effects of the optical fiber cooling devices according to the first to fifth embodiments, the tapered portion is formed at the end of the perforated plate 50, so Pressure loss due to expansion can be minimized.

  INDUSTRIAL APPLICABILITY The present invention can be used, for example, in a residual stress improving method for an inner surface of a welded part such as a pipe or a nozzle using a laser, particularly in an after-sales work for a nuclear power plant.

The figure which showed the structural example of the optical fiber cooling device which concerns on the 1st Embodiment of this invention The figure which showed the structural example of the optical fiber cooling device which concerns on the 2nd Embodiment of this invention. The figure which showed the structural example of the optical fiber cooling device which concerns on the 3rd Embodiment of this invention. The figure which showed the structure of the outer cylinder in the optical fiber cooling device which concerns on the 4th and 5th embodiment of this invention The figure which showed the structure of the jig | tool in the optical fiber cooling device which concerns on the 5th Embodiment of this invention. The figure which showed the structure of the jacket in the optical fiber cooling device which concerns on the 6th Embodiment of this invention The figure which showed the structure of the jacket in the optical fiber cooling device which concerns on the 7th Embodiment of this invention The figure which showed the structure of the jacket in the optical fiber cooling device which concerns on the 8th Embodiment of this invention The figure which showed the structure of the jacket in the optical fiber cooling device which concerns on the 9th Embodiment of this invention Diagram showing residual stress improvement method using laser Diagram showing how laser is transmitted from an outdoor laser oscillator to an indoor construction site using an optical fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser oscillator 11 Optical fiber 12 Construction object 13 Construction part 14 Outer cylinder 14s Small outer cylinder 15,22 Refrigerator 16 Dehumidifier 17 Blower 18 Building 19 Laying part 20 Optical fiber drum 21 Cover 30 Bellows cooling pipe 31 Half crack part 32 , 35 Fastener 33 Condensation prevention heat insulating material 34, 36 Magic tape 40 Jig 50 Perforated plate 51 Jacket

Claims (10)

A laser oscillator that oscillates a laser;
An optical fiber for transmitting the laser;
A cylindrical outer tube for housing the optical fiber;
An optical fiber cooling apparatus comprising: a cooling unit that supplies a cooling medium into the outer cylinder and cools the optical fiber in a predetermined temperature range in order to suppress expansion or contraction due to a temperature change of the optical fiber. The optical fiber cooling device according to claim 1,
The laser oscillator is installed outdoors,
The optical fiber cooling device according to claim 1, wherein the outer cylinder is installed only in a portion of the optical fiber laid outside. In the optical fiber cooling device according to claim 2,
An optical fiber cooling device, wherein the outer cylinder has a surface subjected to reflection processing. In the optical fiber cooling device according to any one of claims 1 to 3,
An optical fiber drum having an appropriate length by winding the optical fiber;
An optical fiber drum cooling means for cooling in a predetermined temperature range in order to suppress expansion or contraction due to a temperature change of the optical fiber wound around the optical fiber drum;
The optical fiber cooling apparatus according to claim 1, wherein the outer cylinder includes a plurality of small outer cylinders, and the cooling means is installed for each of the small outer cylinders. In the optical fiber cooling device according to any one of claims 1 to 4,
The optical fiber cooling device according to claim 1, wherein the outer cylinder has a half crack shape. In the optical fiber cooling device according to claim 5,
The outer tube includes a jig for holding the optical fiber at the center inside the outer tube. In the optical fiber cooling device according to any one of claims 1 to 6,
The optical fiber cooling apparatus according to claim 1, wherein the outer cylinder includes a cylindrical jacket whose inner surface is a perforated plate at an end portion in the axial direction. In the optical fiber cooling device according to claim 7,
The jacket is characterized in that the pitch of the holes formed in the perforated plate decreases as it goes toward the axial end of the outer cylinder, and increases as it goes inward in the axial direction of the outer cylinder. Fiber cooling device. In the optical fiber cooling device according to claim 7 or 8,
The jacket is such that the thickness of the wall portion in the radial direction becomes thicker as it goes to the end portion in the axial direction of the outer cylinder and becomes thinner as it goes inward in the axial direction of the outer cylinder. apparatus. In the optical fiber cooling device according to any one of claims 7 to 9,
An optical fiber cooling device, wherein a tapered portion is formed at an inner end portion of the outer cylinder in the axial direction of the perforated plate.

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