A method for preparing an optical fiber penetrator and a sealing structure of the optical fiber penetrator

Abstract

The present invention provides a method for preparing an optical fiber through-piece, comprising: S1, fixing an optical fiber in a casting mold and placing a corresponding metal material into the casting mold together; S2, heating the optical fiber and the metal material synchronously, and waiting for the metal material to melt and wrap the optical fiber, and then waiting for the metal material to solidify. The present invention also discloses a sealing structure for an optical fiber through-piece, wherein the optical fiber through-piece is made by the above preparation method. The sealing structure includes a convex block located in the middle of the through-piece, and also includes a pipe socket and a compression cap. The pipe socket and the compression cap are respectively located on both sides of the convex block independently. The other end of the compression cap cooperates with the pipe socket to squeeze the convex block so that the convex block fits and seals with the pipe socket. By forming a relatively thick metal layer outside the optical fiber, compared with conventional optical fiber through-pieces, the sealing effect of the present invention far exceeds that of conventional optical fiber through-pieces; moreover, by heating the optical fiber and the metal material synchronously, when the metal material melts and wraps the optical fiber, the optical fiber is not easily broken.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber penetrators, and particularly to a preparation method of an optical fiber penetrator and a sealing structure of an optical fiber penetrator. Background Art

[0002] Under high temperature and high pressure conditions, the application of optical fiber measurement technology has huge application scenarios. However, due to the influence of the optical fiber's own coating layer and strength, there is a lack of penetrators that can transition from high temperature and high pressure to normal temperature and pressure and can be sealed.

[0003] Conventional optical fiber penetrators mainly use methods such as gluing and epoxy resin to seal with optical fibers. However, such penetrators cannot be used for a long time under the conditions of temperature > 350 °C and internal and external pressure difference > 10 MPa. Summary of the Invention

[0004] The main purpose of the present invention is to provide a preparation method of an optical fiber penetrator and a sealing structure of an optical fiber penetrator with good sealing effect and capable of being used for a long time under high temperature and high pressure conditions.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A preparation method of an optical fiber penetrator, comprising:

[0006] S1. Fix the optical fiber in a casting mold, and place the corresponding metal material into the casting mold together;

[0007] S2. Heat the optical fiber and the metal material synchronously. After the metal material melts and wraps the optical fiber, wait for the metal material to solidify.

[0008] Further, after S2, it further includes:

[0009] S3. Perform machining on both ends of the solidified metal material to machine out joints connected to the corresponding optical fiber instruments.

[0010] Further, the thickness of the solidified metal material is greater than 1 mm.

[0011] Further, in S2, by heating the casting mold, heat the optical fiber and the metal material located in the casting mold.

[0012] Further, the casting mold is a graphite mold, and the heating method is eddy current heating.

[0013] Further, when heating the casting mold, the inside of the casting mold is in a vacuum state.

[0014] Further, in S1, both ends of the optical fiber extend out of the casting mold.

[0015] Further, the metal material is one of copper, nickel-based stainless steel, 316 stainless steel, or 321 stainless steel.

[0016] Further, the casting mold is divided into a lower mold and an upper mold. A first melting groove is formed in the middle of the lower mold, and a second melting groove is formed in the upper mold corresponding to the position of the first melting groove. The first melting groove and the second melting groove cooperate to form a melting cavity, and the inner contour of the melting cavity coincides with the outer contour of the through-piece. A shrinkage compensation hole communicating with the first melting groove is formed in the upper mold, and the metal material for melting compensation is placed in the shrinkage compensation hole.

[0017] Further, through grooves for the optical fiber to pass through are formed at both ends of the upper mold, and a pressing component is further arranged on the upper mold to fix the optical fiber by pressing.

[0018] Further, the pressing component includes a pressing groove formed at the position of the through groove on the upper mold. The pressing groove communicates with the through groove, and a pressing block is arranged in the pressing groove; it also includes a screw hole penetrating through the pressing groove and the outside of the upper mold, and a screw is spirally engaged in the screw hole. The end of the screw is connected to the pressing block.

[0019] Further, the casting mold is heated in a horizontal posture. The upper mold is located above the lower mold, and the shrinkage compensation hole is located at the top of the melting cavity and communicates with the melting cavity.

[0020] Further, the optical fiber and the metal material are heated synchronously by means of constant temperature heating; the temperature rise rate of the constant temperature heating includes a rapid heating stage, a transition stage, a melting stage, and a stepped cooling stage, where:

[0021] In the rapid heating stage, the temperature rapidly rises from room temperature to a temperature lower than the melting point temperature of the corresponding metal.

[0022] In the transition stage, after the rapid heating stage, it is kept at a constant temperature for not less than 5 minutes, and then the temperature is gradually increased to a temperature higher than the melting point temperature of the corresponding metal. During the temperature increase process, every time the temperature rises by 100 °C, it needs to be kept at a constant temperature for not less than 5 minutes.

[0023] In the melting stage, it is kept at a constant temperature above the melting point temperature of the corresponding metal until the metal material is completely melted and wraps the optical fiber.

[0024] In the stepped cooling stage, the temperature is decreased in gradients until it reaches room temperature.

[0025] An optical fiber through-piece sealing structure, the optical fiber through-piece is made by the above preparation method, and the sealing structure includes a convex block located in the middle of the through-piece. Arc chamfers are arranged on both sides of the convex block, and the arc chamfers are annularly distributed on both sides of the convex block;

[0026] It also includes a pipe socket and a compression nut. The pipe socket and the compression nut are respectively independent of both sides of the convex block. The pipe socket is hollow. One end of the pipe socket corresponding to the convex block is provided with a conical surface for contacting and fitting with the corresponding arc chamfer. One end of the penetrating member passes through the compression nut. One end of the compression nut corresponding to the convex block contacts the convex block. The other end of the compression nut cooperates with the pipe socket to squeeze the convex block so that the convex block fits and seals with the pipe socket.

[0027] Further, one end of the pipe socket corresponding to the compression nut is provided with an external thread, and the inner side of the compression nut is provided with an internal thread that cooperates with the external thread.

[0028] The beneficial effects of the present invention are reflected in:

[0029] In the present invention, by melting and wrapping the optical fiber with a metal material, a relatively thick metal layer is formed on the outside of the optical fiber. Compared with the conventional optical fiber penetrating member, in this application, the penetrating member is directly prepared on the corresponding optical fiber, and the sealing effect far exceeds that of the conventional optical fiber penetrating member, and it has excellent high temperature and high pressure resistance; moreover, by synchronously heating the optical fiber and the metal material, the temperatures of the optical fiber and the metal material are made close. When the metal material melts and wraps the optical fiber, the optical fiber is not easily broken. Description of the Drawings

[0030] In the drawings:

[0031] Figure 1 is the overall view of the casting mold described in the present invention;

[0032] Figure 2 is the half-sectional view of the casting mold described in the present invention;

[0033] Figure 3 is the half-sectional view of the sealing structure of the optical fiber penetrating member described in the present invention;

[0034] Figure 4 is the structural view of the penetrating member described in the present invention.

[0035] Description of the Reference Numerals:

[0036] 1. Casting mold; 11. Lower mold; 12. Upper mold; 13. Melting and casting cavity; 14. Shrinkage compensation hole; 15. Penetrating groove; 16. Pressing groove; 17. Pressing block; 18. Screw hole; 19. Screw; 2. Penetrating member; 21. Convex block; 3. Pipe socket; 4. Compression nut. Detailed Embodiments

[0037] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the invention without creative efforts belong to the scope of protection of the invention.

[0038] See Figures 1 to 4 。

[0039] The present invention discloses a method for preparing an optical fiber penetrator, including:

[0040] S1. Fix the optical fiber in the casting mold 1 and place the corresponding metal material into the casting mold 1 together;

[0041] S2. Heat the optical fiber and the metal material synchronously. After the metal material melts and wraps the optical fiber, wait for the metal material to solidify.

[0042] In the method for preparing the optical fiber penetrator 2 of the present invention, by melting the metal material and wrapping the optical fiber, a relatively thick metal layer is formed on the outside of the optical fiber. Compared with the conventional optical fiber penetrator 2, in the present application, the penetrator 2 is directly prepared on the corresponding optical fiber, and the sealing effect far exceeds that of the conventional optical fiber penetrator 2, and it has excellent high temperature and high pressure resistance (as long as the metal does not melt, it can be sealed all the time);

[0043] Moreover, in the present application, by heating the optical fiber and the metal material synchronously, the temperatures of the optical fiber and the metal material are close, and the optical fiber is not easily broken. In this way, the highest melting point of the metal material only needs to be slightly lower than the melting point of the optical fiber (the melting point of the conventional optical fiber is 1723 ± 5 °C); if the molten metal solution is directly poured into the casting mold 1, it is easy to cause too large a temperature difference between the optical fiber and the metal material, the optical fiber is easy to break, and the solidified metal material is prone to have sand holes, small bubbles, etc.

[0044] During use, one end of the optical fiber penetrator 2 is directly placed in a high temperature and high pressure environment, the other end of the optical fiber penetrator 2 is located on the side of normal temperature and differential pressure, and the outer wall of the optical fiber penetrator 2 is in sealing cooperation with the object to be measured.

[0045] In one embodiment, after S2, it further includes: S3. Machine-process both ends of the solidified metal material to process joints for connecting to the corresponding optical fiber instrument.

[0046] In specific implementation, the burrs on the surface of the metal material are removed by machining, and then threads are machined at both ends of the metal material to connect to an optical fiber instrument with an FC / APC optical fiber interface.

[0047] In one embodiment, the thickness of the solidified metal material is greater than 1 mm. In specific implementation, a metal layer greater than 1 mm facilitates subsequent machining processes.

[0048] In one embodiment, in S2, by heating the casting mold 1, the optical fiber and the metal material located within the casting mold 1 are heated. With this design, the heating will be more uniform.

[0049] In one embodiment, the casting mold 1 is a graphite mold, and the heating method is eddy current heating. In specific implementation, with the eddy current heating method of an intermediate frequency furnace, the mold is completely placed inside the heating coil, and the direct heating body is the surface of the graphite mold. The minimum wall thickness of the mold can be set to be greater than 3 mm to achieve uniform temperature throughout the mold.

[0050] In one embodiment, in S1, both ends of the optical fiber extend out of the casting mold 1. With this design, the extended part of the optical fiber is used for monitoring the state of the optical fiber during the processing (such as detecting whether the optical fiber is broken and detecting the transmission condition of the optical fiber). Specifically, the extended part of the optical fiber is connected to an optical fiber state monitoring device, and the state of the optical fiber during the processing is monitored through the optical fiber state monitoring device.

[0051] In one embodiment, the metal material is one of copper, nickel-based stainless steel, 316 stainless steel, or 321 stainless steel; among them, when the use temperature ≤ 350 °C and the pressure ≤ 20 MPa, copper can be selected as the material. When the use temperature is 350 - 900 °C and the pressure is less than 40 MPa, nickel-based stainless steel can be selected as the material. When the use temperature is higher than 900 °C, 316 stainless steel or 321 stainless steel can be used.

[0052] In one embodiment, the casting mold 1 is divided into a lower mold 11 below and an upper mold 12 above. A first casting groove is provided in the middle of the lower mold 11, and a second casting groove is provided at the position corresponding to the first casting groove on the upper mold 12. The first casting groove and the second casting groove cooperate to form a casting cavity 13. The internal contour of the casting cavity 13 coincides with the external contour of the penetrator 2. A shrinkage compensation liquid hole 14 communicating with the first casting groove is provided on the upper mold 12, and the metal material for molten liquid compensation is placed in the shrinkage compensation liquid hole 14.

[0053] In specific implementation, when the corresponding metal material is placed into the casting mold 1 together, the metal material is placed not only in the casting cavity 13 but also in the shrinkage compensation liquid hole 14. In this way, after the metal material in the shrinkage compensation liquid hole 14 melts, it will flow into the casting cavity 13 to fill the casting cavity 13, making the casting cavity 13 full of metal solution to ensure obtaining a penetrator 2 with qualified dimensions.

[0054] In one embodiment, through holes 15 for the optical fiber to pass through are provided at both ends of the upper mold 12, and a pressing component is further provided on the upper mold 12;

[0055] The pressing component includes a pressing groove 16 formed at the position of the corresponding through groove 15 on the upper die 12. The pressing groove 16 is communicated with the through groove 15, and a pressing block 17 is arranged in the pressing groove 16; it also includes a screw hole 18 penetrating through the pressing groove 16 and the outside of the upper die 12. A screw 19 is in screw fit in the screw hole 18, and the end of the screw 19 is connected to the pressing block 17.

[0056] In specific implementation, the end of the screw 19 is rotatably connected to the pressing block 17. During work, the optical fiber is passed through the through groove 15. After the metal material is placed into the casting mold 1, the upper die 12 and the lower die 11 are fixed together by bolts, and then the screw 19 is rotated to drive the pressing block 17 to move downward to press the optical fiber and fix the optical fiber; before fixing the optical fiber, the optical fiber can be straightened by pulling both ends of the optical fiber, and then the optical fiber is fixed to avoid the optical fiber bending in the mold and affecting the transmission quality.

[0057] In an embodiment, the casting mold 1 is heated in a horizontal posture. The upper die 12 is located above the lower die 11, and the shrinkage compensation hole 14 is located at the top of the melting cavity 13 and is communicated with the melting cavity 13. Designed in this way, using gravity, the metal solution in the shrinkage compensation hole 14 automatically flows into the melting cavity 13, and the horizontal posture enables the metal solution to be evenly distributed in the melting cavity 13.

[0058] In an embodiment, when the casting mold 1 is heated, the inside of the casting mold 1 is in a vacuum state.

[0059] In specific implementation, the inside of the casting mold 1 is in a vacuum state through a vacuum device (such as a vacuum pump). On the one hand, this can protect the graphite mold from oxidizing with air in a high-temperature environment, and on the other hand, it is also convenient to discharge the gas in the melting cavity 13, further reducing the possibility of bubbles and sand holes generated in the body of the penetrating part 2 and improving the casting quality of the penetrating part 2.

[0060] In an embodiment, the optical fiber and the metal material are heated synchronously by means of constant-temperature heating; the temperature rise rate of the constant-temperature heating includes a rapid heating stage, a transition stage, a melting stage, and a stepped cooling stage, where:

[0061] In the rapid heating stage, the temperature rapidly rises from room temperature to a temperature lower than the melting point temperature of the corresponding metal;

[0062] In the transition stage, after the rapid heating stage, it is kept at a constant temperature for no less than 5 minutes, and then the temperature is gradually increased to a temperature higher than the melting point temperature of the corresponding metal. During the process of the temperature rising in steps, each time the temperature rises by 100 °C, it needs to be kept at a constant temperature for no less than 5 minutes;

[0063] The melting stage is maintained at a constant temperature above the melting point temperature of the corresponding metal until all the metal materials are melted and wrap the optical fiber;

[0064] The stepwise cooling stage involves cooling in gradients until reaching room temperature.

[0065] In specific implementation, during the rapid heating stage, while rapidly heating, the temperature is not allowed to reach the melting point temperature of the metal, and then it is maintained for a period of time, which can allow the interior of the mold to expand sufficiently by heat (equivalent to preheating). The stepped temperature rise enables the metal inside the casting cavity 13 and the metal near the inner wall of the casting cavity 13 to melt almost simultaneously, reducing the existence duration of the solid-liquid coexistence state. After all the metal is melted and wraps the optical fiber, it is cooled in gradients to release the internal stress generated during solidification.

[0066] The present invention also discloses a sealing structure for an optical fiber penetrator. The optical fiber penetrator 2 is made by the above-mentioned preparation method. The sealing structure includes a convex block 21 in the middle of the penetrator 2. Arc chamfers are provided on both sides of the convex block 21, and the arc chamfers are annularly distributed on both sides of the convex block 21;

[0067] It also includes a pipe socket 3 and a compression cap 4. The pipe socket 3 and the compression cap 4 are respectively independent on both sides of the convex block 21. The pipe socket 3 is hollow. One end of the pipe socket 3 corresponding to the convex block 21 is provided with a conical surface for contacting and fitting with the corresponding arc chamfer. One end of the penetrator 2 passes through the compression cap 4. One end of the compression cap 4 corresponding to the convex block 21 contacts the convex block 21. The other end of the compression cap 4 cooperates with the pipe socket 3 to squeeze the convex block 21 to make the convex block 21 fit and seal with the pipe socket 3.

[0068] In specific implementation, the pipe socket 3 is welded as a structural reinforcement on a high-temperature and high-pressure pipeline / chamber. By squeezing the convex block 21 in the middle of the penetrator 2 through the compression cap 4, the convex block 21 is made to fit and seal with the pipe socket 3 to achieve sealing. Compared with existing sealing forms such as sealants and gaskets, this purely physically structured sealing has significantly improved reliability and durability. Moreover, under the influence of thermal expansion, the higher the temperature, the better the sealing effect.

[0069] The present invention also discloses a sealing structure for an optical fiber penetrator. The pipe socket 3 is provided with an external thread at one end corresponding to the compression cap 4, and the inner side of the compression cap 4 is provided with an internal thread that cooperates with the external thread. With this design, the compression cap 4 and the pipe socket 3 are connected together by screwing, and a pre-pressure can be provided for the convex block 21 in the form of pre-tightening to improve the sealing performance of the convex block 21 fitting with the pipe socket 3.

[0070] It should be noted that if the invention embodiments involve directional indications (such as up and down), the directional indications are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0071] In addition, if the invention embodiments involve descriptions such as "first" and "second", the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, "a plurality" means two or more. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the invention.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an optical fiber penetrator, characterized in that, Including: S1. Fix the optical fiber in the casting mold (1), and place the corresponding metal material into the casting mold (1) together; S2. Heat the optical fiber and the metal material synchronously. After the metal material melts and wraps the optical fiber, wait for the metal material to solidify. The thickness of the solidified metal material is greater than 1 mm; In S2, by heating the casting mold (1), heat the optical fiber and the metal material located in the casting mold (1).

2. The method for preparing the optical fiber through member according to claim 1, wherein, After S2, it further includes: S3. Machine-process both ends of the solidified metal material to process joints for connecting to the corresponding optical fiber instrument.

3. The method for preparing the optical fiber through-piece according to claim 1, characterized in that, The casting mold (1) is a graphite mold, and the heating method is eddy current heating.

4. The method for preparing the optical fiber through-piece according to claim 1, wherein When heating the casting mold (1), the inside of the casting mold (1) is in a vacuum state.

5. The method for preparing an optical fiber through-piece according to claim 1 or 2, characterized in that, In S1, both ends of the optical fiber extend out of the casting mold (1).

6. The method for preparing an optical fiber through - piece according to claim 1 or 2, characterized in that, The metal material is one of copper, nickel-based stainless steel, 316 stainless steel, or 321 stainless steel.

7. The method for preparing an optical fiber through-piece according to claim 1 or 2, characterized in that, The casting mold (1) is divided into a lower mold (11) and an upper mold (12). A first casting groove is provided in the middle of the lower mold (11). A second casting groove is provided at the position corresponding to the first casting groove on the upper mold (12). The first casting groove and the second casting groove cooperate to form a casting cavity (13). The inner contour of the casting cavity (13) coincides with the outer contour of the through-piece (2). A shrinkage compensation liquid hole (14) communicating with the first casting groove is provided on the upper mold (12). The metal material for molten liquid compensation is placed in the shrinkage compensation liquid hole (14).

8. The method for preparing the optical fiber through-piece according to claim 7, characterized in that, Through grooves (15) for the optical fiber to pass through are provided at both ends of the upper mold (12). A pressing component is further provided on the upper mold (12) to fix the optical fiber by pressing.

9. The method for preparing an optical fiber through-piece according to claim 8, characterized in that, The pressing component includes a pressing groove (16) provided at the position corresponding to the through groove (15) on the upper mold (12). The pressing groove (16) communicates with the through groove (15). A pressing block (17) is provided in the pressing groove (16); it also includes a screw hole (18) penetrating through the pressing groove (16) and the outside of the upper mold (12). A screw (19) is spirally engaged in the screw hole (18), and the end of the screw (19) is connected to the pressing block (17).

10. The method for preparing the optical fiber through - penetration member according to claim 7, wherein, The casting mold (1) is heated in a horizontal posture. The upper mold (12) is located above the lower mold (11). The shrinkage compensation liquid hole (14) is located at the top of the casting cavity (13) and communicates with the casting cavity (13).

11. The method for preparing an optical fiber through-piece according to claim 1 or 2, characterized in that, Adopt a constant temperature heating method to heat the optical fiber and the metal material synchronously; the temperature rise rate of the constant temperature heating includes a rapid heating stage, a transition stage, a melting stage, and a stepwise cooling stage, where: In the rapid heating stage, the temperature rapidly rises from room temperature to a temperature lower than the melting point temperature of the corresponding metal; In the transition stage, after the rapid heating stage, keep the temperature constant for no less than 5 minutes, and then gradually increase the temperature to a temperature higher than the melting point temperature of the corresponding metal in gradients. During the temperature increase process, for every 100 °C increase, keep the temperature constant for no less than 5 minutes; In the melting stage, keep the temperature constant at a temperature higher than the melting point temperature of the corresponding metal until the metal material completely melts and wraps the optical fiber; During the stepwise cooling stage, the temperature is decreased in gradients until the room temperature is reached.

12. A sealing structure for an optical fiber penetrator, characterized in that, The optical fiber penetrator (2) is made by using the manufacturing method described in any one of claims 1 to 11. The sealing structure includes a convex block (21) located in the middle of the penetrator (2). Arc chamfers are provided on both sides of the convex block (21), and the arc chamfers are annularly distributed on both sides of the convex block (21). It further includes a pipe support (3) and a compression nut (4). The pipe support (3) and the compression nut (4) are respectively independent on both sides of the convex block (21). The pipe support (3) is hollow. One end of the pipe support (3) corresponding to the convex block (21) is provided with a conical surface for contacting and fitting with the corresponding arc chamfer. One end of the penetrator (2) passes through the compression nut (4). One end of the compression nut (4) corresponding to the convex block (21) contacts the convex block (21). The other end of the compression nut (4) cooperates with the pipe support (3) to squeeze the convex block (21) so that the convex block (21) fits and seals with the pipe support (3).

13. The optical fiber through-piece sealing structure according to claim 12, characterized in that, One end of the pipe support (3) corresponding to the compression nut (4) is provided with an external thread, and the inner side of the compression nut (4) is provided with an internal thread that mates with the external thread.

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