Reusable wire drawing furnace

Abstract

The invention discloses a reusable fiber drawing furnace, and particularly relates to the field of fiber drawing furnaces, the reusable fiber drawing furnace comprises a furnace frame, an optical fiber drawing furnace is placed on the outer surface of the furnace frame, a clamping plate assembly is arranged on the outer surface of the furnace frame, and the optical fiber drawing furnace is fixed on the outer surface of the furnace frame through the clamping plate assembly; a top frame is arranged above the optical fiber drawing furnace, a chuck is fixedly mounted at the bottom end of the top frame, and a plurality of optical fiber prefabricated parts are fixed through the chuck; a furnace lining is fixedly installed in the optical fiber drawing furnace, and a heating assembly is arranged in the furnace lining. According to the invention, a plurality of optical fiber prefabricated members are fixed through the chuck and can be drawn at the same time, so that the production efficiency is improved; stable temperature field distribution can be formed when a plurality of optical fibers are drawn at the same time, so that the temperature field distribution is kept stable when the optical fibers are drawn; the temperature in the furnace is precisely controlled through the combined use of the thermocouple and the temperature controller, so that an ideal wire drawing environment is provided, the out-of-roundness of the optical fiber is reduced to zero as far as possible, and the connection loss of the optical fiber and the dispersion of a polarizing film are reduced.

Description

Technical Field

[0001] The present invention relates to the field of drawing furnaces, and more particularly, to a reusable drawing furnace. Background Art

[0002] The drawing of optical fibers is to melt a large-diameter optical fiber preform online and draw it into an optical fiber with a diameter meeting the requirements. The heating device for melting the optical fiber preform (usually called a drawing furnace) is one of the most critical equipment in the drawing process, and this equipment directly affects many technical indicators of the optical fiber, such as the diameter fluctuation of the bare optical fiber, the optical fiber break point rate, attenuation, PMD, and the geometric parameters of the optical fiber.

[0003] Optical fibers can be divided into communication optical fibers and special optical fibers according to their uses. Currently, special optical fibers have been widely used in scientific and technological fields such as communication, sensing, biomedicine, material processing, and military industry. The market for special optical fibers is being rapidly opened. There are many types of special optical fibers, including plastic optical fibers, microstructured hollow optical fibers, and multi-component doped optical fibers. Generally, after SiO2 is deeply doped with multiple components, the melting point of the glass rod can be reduced to below 1000 °C, and the melting point of plastic optical fiber drawing is even lower. Therefore, the drawing of special optical fibers requires precise temperature control in the range of 500-3000 °C. Therefore, the temperature measurement range and accuracy of the heating furnace will directly affect the production and manufacturing of special optical fibers.

[0004] Generally, the process of manufacturing an optical fiber bundle includes the steps of manufacturing an optical fiber preform and drawing an optical fiber from the preform. The optical fiber drawing equipment is used to draw an optical fiber from the preform. There are several processing devices in the optical fiber drawing equipment arranged vertically in the drawing tower according to the processing sequence. The drawing process is carried out in sequence according to the arrangement order of the processing devices of the drawing equipment.

[0005] In traditional optical fiber drawing equipment for optical fiber drawing, the optical fiber preform fixed by a chuck is heated to a high enough temperature to melt. In the furnace, it is moved up and down by a feeding device and then drawn out into an optical fiber. The drawn optical fiber is controlled to a suitable diameter by a diameter controller, then cooled to the required temperature by a cooling unit, and then coated. The cooled optical fiber is coated while passing through a coater, and then the ultraviolet-curable polymer coated on the optical fiber is cured while the optical fiber passes through multiple UV curing units. In this case, the coating material is coated around the optical fiber through its viscosity and surface tension.

[0006] However, traditional optical fiber drawing equipment has the problem of low productivity because the processing devices arranged in the drawing tower can only draw one optical fiber at a time.

[0007] On the other hand, there are also high requirements for the distribution of the temperature field during the fiber drawing process. This is because the fluctuation of the temperature field is the main cause of the fiber non-circularity, and the non-circularity will cause link losses during the fiber coupling process and also cause relatively large polarization mode dispersion (PMD), thereby affecting the fiber performance.

[0008] In order to reduce the non-circularity to as close to 0 as possible, one of the mainstream methods is to rotate the fiber preform. The international patent application WO97 / 26221 notes that the reduction of PMD caused by rotation is proportional to the rotation speed, and generally a very high rotation speed is required to handle the asymmetry of ordinary fibers. For example, the rotation speed is greater than 5000 revolutions per minute, and rotating the preform at such a speed is not a suitable solution for large-scale fiber production.

[0009] U.S. Patent 4504300 tries to solve the disadvantages related to the rotation of the preform. This patent relates to the technology of manufacturing fibers with chiral structures. This patent proposes a new rotation method, which consists of rotating the fiber without rotating the preform. Specifically, a device is disclosed, which includes means for twisting the fiber during the fiber drawing process and arranged immediately below the preform. Such twisting means includes a rotating hoop supporting three rollers. The twisted fiber is coated using a coating device and then cooled using a rapid cooling device, which helps to solidify this twist.

[0010] As observed in WO97 / 26221, the disadvantage of this technology is that it is very easy to damage the fiber surface because the fiber surface contacts the above-mentioned rollers before being properly protected by a coating film. In addition, the gas flow in the furnace is disturbed and the fluctuation of the fiber diameter becomes larger. As a result, the connection loss may increase when connecting by means of an optical connector or a fused connection end. Summary of the Invention

[0011] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a multiplex fiber drawing furnace. By using a chuck to fix multiple fiber preforms, multiple fiber preforms can be drawn simultaneously, improving the production efficiency; when multiple fibers are drawn simultaneously, a relatively stable temperature field distribution can be formed, keeping the temperature field distribution relatively stable during fiber drawing; by combining the use of a thermocouple and a temperature controller, the temperature in the furnace can be precisely controlled, thereby providing an ideal drawing environment, reducing the non-circularity of the fiber to as close to 0 as possible, and thus reducing the fiber connection loss and polarization mode dispersion.

[0012] To achieve the above object, the present invention provides the following technical solution: A multiplex fiber drawing furnace, including a furnace frame, on the outer surface of which a fiber drawing furnace is placed, and a clamping plate assembly is arranged on the outer surface of the furnace frame, and the fiber drawing furnace is fixed on the outer surface of the furnace frame through the clamping plate assembly; Above the optical fiber drawing furnace, there is a top frame. At the bottom end of the top frame, a chuck is fixedly installed, and several optical fiber preforms are fixed by the chuck. Inside the optical fiber drawing furnace, a furnace lining is fixedly installed, and a heating component is arranged inside the furnace lining.

[0013] In a preferred embodiment, the heating component includes a first heating wire and a second heating wire arranged inside the furnace lining. The first heating wire and the second heating wire are distributed in two layers. The second heating wire is horizontally perpendicular to the side surface, and the first heating wire is horizontally perpendicular to the front surface. A plurality of through holes are formed on the outer surfaces of the upper and lower ends of the furnace lining.

[0014] In a preferred embodiment, thermocouples are fixedly installed on the outer surfaces around the optical fiber drawing furnace, and the first heating wire and the second heating wire are respectively connected to the thermocouples arranged on the side of the optical fiber drawing furnace.

[0015] In a preferred embodiment, the outer layer of the optical fiber drawing furnace is composed of a shell and a heat insulation layer, and the heat insulation layer is located between the shell and the furnace lining. The inner side of the heat insulation layer is wrapped by heat-resistant stainless steel. The shell is a vertical cuboid shell, and the shell is made of high-quality stainless steel plates through flanging and welding.

[0016] In a preferred embodiment, a temperature controller is fixedly installed on the outer surface of the optical fiber drawing furnace, and an air inlet is formed on the outer surface of the optical fiber drawing furnace.

[0017] In a preferred embodiment, side frames are fixedly installed on the outer surfaces on both sides of the top frame, and hydraulic cylinders are fixedly installed on both sides of the top outer surface of the furnace frame. The top end of the output shaft of the hydraulic cylinder is fixedly connected to the outer surface of the side frame.

[0018] In a preferred embodiment, a plurality of card slots are formed on the outer surface at the bottom end of the chuck, and clamping plates are arranged around the inner wall of the card slots.

[0019] In a preferred embodiment, a bottom groove is formed on the outer surface of the furnace frame below the bottom end of the optical fiber drawing furnace, and bottom frames are fixedly installed at the four corners of the bottom end of the furnace frame.

[0020] In a preferred embodiment, the card board assembly includes card boards arranged at the four corners of the bottom end of the optical fiber drawing furnace on the top outer surface of the furnace frame. A slider is fixedly installed at the bottom end of the card board. A chute is formed on the outer surface of the furnace frame below the card board, and the slider is arranged inside the chute. The card board is slidably connected to the furnace frame through the slider.

[0021] In a preferred embodiment, turntables are rotatably connected to the four corners of the furnace rack, a screw rod is rotatably installed inside the chute, the slider is sleeved on the outer surface of the screw rod, and the slider is threadedly connected to the screw rod. One end of the screw rod is fixedly connected to one end of the turntable.

[0022] Technical effects and advantages of the present invention: 1. By using the chuck to fix multiple optical fiber preforms, multiple optical fiber preforms can be drawn simultaneously, improving production efficiency; 2. When multiple optical fibers are drawn simultaneously, a relatively stable temperature field distribution can be formed, maintaining a relatively stable temperature field distribution during optical fiber drawing; 3. By using the combination of a thermocouple and a temperature controller, the temperature inside the furnace can be precisely controlled, thereby providing an ideal drawing environment, reducing the out-of-roundness of the optical fiber to as close to 0 as possible, and thus reducing the optical fiber connection loss and polarization mode dispersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall structure of the present invention Figure I 。

[0024] Figure 2 is a schematic diagram of the overall structure of the present invention Figure II 。

[0025] Figure 3 is a schematic diagram of the structure of the fiber drawing furnace of the present invention.

[0026] Figure 4 is a schematic diagram of the internal structure of the fiber drawing furnace of the present invention.

[0027] Figure 5 is a schematic diagram of the structure of the furnace rack of the present invention.

[0028] Figure 6 is a schematic diagram of the installation structure of the clamping plate assembly of the present invention.

[0029] Figure 7 is a schematic diagram of the structure of the chuck of the present invention.

[0030] Reference numerals are: 1. Furnace rack; 11. Underframe; 12. Hydraulic cylinder; 13. Bottom groove; 14. Chute; 15. Clamping plate; 16. Slider; 17. Screw rod; 18. Turntable; 2. Optical fiber drawing furnace; 21. Outer shell; 22. Furnace lining; 23. Through hole; 24. Temperature controller; 25. First heating wire; 26. Second heating wire; 27. Thermocouple; 3. Top frame; 31. Chuck; 32. Side frame; 33. Card slot; 34. Clamping plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] According to Figures 1-7 A multiplexing wire drawing furnace shown in the figure includes a furnace frame 1. An optical fiber wire drawing furnace 2 is placed on the outer surface of the furnace frame 1. A clamping plate assembly is arranged on the outer surface of the furnace frame 1, and the optical fiber wire drawing furnace 2 is fixed on the outer surface of the furnace frame 1 through the clamping plate assembly. A top frame 3 is arranged above the optical fiber wire drawing furnace 2. A chuck 31 is fixedly installed at the bottom end of the top frame 3, and a plurality of optical fiber preforms are fixed through the chuck 31. A furnace lining 22 is fixedly installed inside the optical fiber wire drawing furnace 2, and a heating assembly is arranged inside the furnace lining 22.

[0033] Furthermore, the heating assembly includes a first heating wire 25 and a second heating wire 26 arranged inside the furnace lining 22. The first heating wire 25 and the second heating wire 26 are distributed in two layers. The second heating wire 26 is horizontally perpendicular to the side surface, and the first heating wire 25 is horizontally perpendicular to the front surface. A plurality of through holes 23 are formed on the outer surfaces of the upper and lower ends of the furnace lining 22. The first heating wire 25 and the second heating wire 26 are distributed at a 90° angle to ensure that each optical fiber preform is in the same and uniform temperature field, so as to reduce the non-circularity in optical fiber drawing, and further reduce the polarization mode dispersion of the optical fiber wire.

[0034] The maximum heating temperature of the first heating wire 25 and the second heating wire 26 can reach 1200 °C to enable the optical fiber preform to reach the molten state and draw downward under the action of gravity.

[0035] Furthermore, thermocouples 27 are fixedly installed on the outer surfaces around the optical fiber wire drawing furnace 2. The first heating wire 25 and the second heating wire 26 are respectively connected to the thermocouples 27 arranged on the side surface of the optical fiber wire drawing furnace 2. The thermocouples 27 are of S type. By measuring the electromotive force generated by the thermocouples 27, the temperature can be determined according to a specific graduation number.

[0036] Further, the outer layer of the optical fiber drawing furnace 2 is composed of a housing 21 and a heat-insulating layer, and the heat-insulating layer is located between the housing 21 and the furnace lining 22. The inner side of the heat-insulating layer is wrapped by heat-resistant stainless steel. The housing 21 is a vertical cuboid housing, and the housing 21 is made of high-quality stainless steel plates by flanging and welding. The heat-insulating layer is located between the housing and the furnace lining. The heat-insulating layer is made of 1260 ceramic fiber cotton. To prevent refractory materials from shedding slag, the inner side of the heat-insulating layer is wrapped by heat-resistant stainless steel, which not only prevents slag from shedding but also blocks heat from leaking to the outside, keeping the temperature of the housing below 40°C.

[0037] Further, a temperature controller 24 is fixedly installed on the outer surface of the optical fiber drawing furnace 2. The temperature controller adopts an SCR thyristor phase-shifting PID output mode, equipped with a 30-segment program temperature controller, which has accurate temperature control and high temperature control accuracy, and has functions such as overload, open-couple, over-temperature protection and over-temperature alarm. This temperature controller is integrated with the electric furnace. An air inlet is provided on the outer surface of the optical fiber drawing furnace 2. Inert gas is introduced from the side of the optical fiber drawing furnace 2 to remove oxygen, so that the optical fiber can have a transition area with a temperature decreasing from high to low, preventing the special optical fiber that has not cooled yet from crystallizing due to oxidation.

[0038] Further, side frames 32 are fixedly installed on the outer surfaces of both sides of the top frame 3, and hydraulic cylinders 12 are fixedly installed on both sides of the top outer surface of the furnace frame 1. The top end of the output shaft of the hydraulic cylinder 12 is fixedly connected to the outer surface of the side frame 32. During the drawing process, the position of the top frame can be adjusted by the hydraulic cylinder 12, so as to adjust the position according to the consumption of the optical fiber preform and ensure the heating position at the bottom end of the optical fiber preform.

[0039] Further, a plurality of card slots 33 are provided on the bottom outer surface of the chuck 31, and clamping plates 34 are arranged around the inner wall of the card slots 33. During use, multiple optical fiber preforms are inserted into the card slots 32 of the chuck 31, and the multiple optical fiber preforms are suspended above the optical fiber drawing furnace 2 by relying on the clamping plates 33, and the lower ends of the optical fiber preforms enter the air above the upper surface of the furnace lining 22 of the optical fiber drawing furnace 2, slightly higher than the horizontal positions of the first heating wire 25 and the second heating wire 26.

[0040] Further, a bottom groove 13 is provided on the outer surface of the furnace frame 1 below the bottom end of the optical fiber drawing furnace 2, and bottom frames 11 are fixedly installed at the four corners of the bottom end of the furnace frame 1.

[0041] Further, the card board assembly includes card boards 15 arranged at the four corners of the bottom end of the fiber drawing furnace 2 on the outer surface of the top end of the furnace frame 1. A slider 16 is fixedly installed at the bottom end of the card board 15. A chute 14 is formed on the outer surface of the furnace frame 1 below the card board 15, and the slider 16 is arranged inside the chute 14. The card board 15 is slidably connected to the furnace frame 1 through the slider 16. Rotating discs 18 are rotatably connected to the four corners of the furnace frame 1. A screw rod 17 is rotatably installed inside the chute 14. The slider 16 is sleeved on the outer surface of the screw rod 17, and the slider 16 is threadedly connected to the screw rod 17. One end of the screw rod 17 is fixedly connected to one end of the rotating disc 18. When disassembling the fiber drawing furnace 2, it is necessary to rotate the rotating discs 18 at the four corners of the furnace frame 1. The rotating discs 18 drive the screw rods 17 to rotate, driving the sliders 16 to slide along the chutes 14, so that the card boards 15 are loosened from the four corners of the fiber drawing furnace 2, releasing the limit on the fiber drawing furnace 2.

[0042] The working principle of the present invention: Refer to the attached drawings of the specification Figures 1-6 During use, multiple optical fiber preforms are inserted into the card slots 32 of the chuck 31. Relying on the clamping plates 33, the multiple optical fiber preforms are suspended above the fiber drawing furnace 2, and the lower ends of the optical fiber preforms enter the air above the upper surface of the furnace lining 22 of the fiber drawing furnace 2, slightly higher than the horizontal positions of the first heating wire 25 and the second heating wire 26. Then, the temperatures of the first heating wire 25 and the second heating wire 26 are raised to the glass softening temperature, causing the preforms to start melting and drawing under the action of gravity. During this process, the thermocouple 27 determines the temperature and temperature field distribution by measuring the electric potential and transmits it to the temperature controller 24. The temperature controller 24 adopts an SCR thyristor phase-shifted PID output mode, equipped with a 30-segment program temperature controller, with accurate temperature control and high temperature control accuracy. By adjusting the temperatures of the first heating wire 25 and the second heating wire 26 through the temperature controller 24, the temperature field distribution inside the fiber drawing furnace 2 is made uniform, achieving an ideal environment for fiber drawing. In addition, inert gas is introduced from the side of the fiber drawing furnace 2 to remove oxygen, so that the fiber can have a temperature transition region from high to low, preventing the special fiber that has not cooled from crystallizing due to oxidation. During the drawing process, the position of the top frame can be adjusted by the hydraulic cylinder 12, so as to adjust the position according to the consumption of the optical fiber preform and ensure the heating position at the bottom end of the optical fiber preform. The outer shell 21 of the fiber drawing furnace 2 is made of section steel. The furnace frame 1 and the fiber drawing furnace 2 are detachable. When disassembling the fiber drawing furnace 2, it is necessary to rotate the rotating discs 18 at the four corners of the furnace frame 1. The rotating discs 18 drive the screw rods 17 to rotate. The screw rods 17 are threadedly connected to the sliders 16, driving the sliders 16 to slide along the chutes 14, so that the card boards 15 are loosened from the four corners of the fiber drawing furnace 2, releasing the limit on the fiber drawing furnace 2.

Claims

1. A multiplex drawing furnace, comprising a furnace frame (1), characterized in that: The outer surface of the furnace frame (1) is provided with a clamping plate assembly, and the optical fiber drawing furnace (2) is fixed on the outer surface of the furnace frame (1) through the clamping plate assembly; A top frame (3) is arranged above the optical fiber drawing furnace (2), and a chuck (31) is fixedly installed at the bottom end of the top frame (3), and a plurality of optical fiber preforms are fixed through the chuck (31); A furnace lining (22) is fixedly installed inside the optical fiber drawing furnace (2), and a heating assembly is arranged inside the furnace lining (22).

2. The multiplexed wire drawing furnace according to claim 1, characterized in that: The heating assembly includes a first heating wire (25) and a second heating wire (26) arranged inside the furnace lining (22). The first heating wire (25) and the second heating wire (26) are distributed in two layers. The second heating wire (26) is horizontally perpendicular to the side surface, and the first heating wire (25) is horizontally perpendicular to the front surface. A plurality of through holes (23) are formed on the outer surfaces of the upper and lower ends of the furnace lining (22).

3. The multiplexed wire drawing furnace according to claim 2, wherein: Thermocouples (27) are fixedly installed on the outer surfaces around the optical fiber drawing furnace (2), and the first heating wire (25) and the second heating wire (26) are respectively connected to the thermocouples (27) arranged on the side surface of the optical fiber drawing furnace (2).

4. The multiplexing wire drawing furnace according to claim 3, characterized in that: The outer layer of the optical fiber drawing furnace (2) is composed of a housing (21) and a heat insulation layer, and the heat insulation layer is located between the housing (21) and the furnace lining (22). The inner side of the heat insulation layer is wrapped by heat-resistant stainless steel. The housing (21) is a vertical cuboid housing, and the housing (21) is made of high-quality stainless steel plates by flanging and welding.

5. A multiplexed wire drawing furnace according to claim 1, characterized in that: A temperature controller (24) is fixedly installed on the outer surface of the optical fiber drawing furnace (2), and an air inlet is formed on the outer surface of the optical fiber drawing furnace (2).

6. The multiplexing wire drawing furnace according to claim 1, wherein: Side frames (32) are fixedly installed on the outer surfaces of both sides of the top frame (3), and hydraulic cylinders (12) are fixedly installed on both sides of the outer surface of the top end of the furnace frame (1). The top end of the output shaft of the hydraulic cylinder (12) is fixedly connected to the outer surface of the side frame (32).

7. A multiplex drawing furnace according to claim 6, characterized in that: A plurality of clamping grooves (33) are formed on the outer surface of the bottom end of the chuck (31), and clamping plates (34) are arranged around the inner walls of the clamping grooves (33).

8. A multiplexing drawing furnace according to claim 1, characterized in that: A bottom groove (13) is formed on the outer surface of the furnace frame (1) below the bottom end of the optical fiber drawing furnace (2), and bottom frames (11) are fixedly installed at the four corners of the bottom end of the furnace frame (1).

9. A multiplexed wire drawing furnace according to claim 1, characterized in that: The clamping plate assembly includes clamping plates (15) arranged at the four corners of the outer surface of the top end of the furnace frame (1) below the bottom end of the optical fiber drawing furnace (2). Sliders (16) are fixedly installed at the bottom ends of the clamping plates (15). A sliding groove (14) is formed on the outer surface of the furnace frame (1) below the clamping plates (15), and the sliders (16) are arranged inside the sliding groove (14). The clamping plates (15) are slidably connected to the furnace frame (1) through the sliders (16).

10. A multiplex drawing furnace according to claim 9, characterized in that: Rotary discs (18) are rotatably connected to the four corners of the furnace frame (1). Screws (17) are rotatably installed inside the sliding grooves (14). The sliders (16) are sleeved on the outer surfaces of the screws (17), and the sliders (16) are threadedly connected to the screws (17). One end of the screw (17) is fixedly connected to one end of the rotary disc (18).

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