Optical fiber preform sintering equipment

Abstract

The utility model discloses optical fiber preform sintering equipment which comprises an outer furnace body and an inner furnace core tube, a plurality of heating bodies are fixed to the inner wall of the outer furnace body through connecting pieces and are sequentially arranged in the length direction of the inner furnace core pipe. A sealing cover arranged above the opening in a covering manner is mounted at the top of the outer furnace body; a connecting rod is arranged on the sealing cover in a sealing and penetrating manner; the side wall of the outer furnace body is connected with an outer furnace exhaust pipe, the sealing cover is connected with an inner furnace exhaust pipe, the bottom of the inner furnace core pipe is communicated with an air inlet pipe, and the air inlet pipe penetrates out of the outer furnace body in a sealed mode. The utility model has the advantages that the loose body of the prefabricated rod can be uniformly sintered through the heating bodies, and the unburned bad area of the loose body of the prefabricated rod is improved in a targeted manner; the sintering equipment disclosed by the utility model is a vacuum furnace integrating dewatering and sintering functions, and compared with a traditional double-furnace structure, the occupied space of a furnace body is reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of optical fiber preform manufacturing equipment, and in particular to an optical fiber preform sintering equipment. Background Technology

[0002] Currently, existing optical fiber manufacturing technologies mainly include optical fiber preform manufacturing and fiber drawing. Optical fiber preform manufacturing first uses external vapor deposition (OVD) to deposit the outer cladding or uses RIC to create the cladding to form a porous preform. Then, the porous preform is transformed into a transparent glass body through dehydration and sintering. The sintering process involves placing the preform in a heating furnace, raising the temperature to a certain level, and introducing process gases such as N2, Cl2, or argon. After dehydration and dehydroxylation, the preform is sintered to form a transparent optical rod, which is then subjected to manufacturing processes such as fiber drawing.

[0003] When sintering in existing heating furnaces, uneven temperature control can lead to incomplete sintering. The existing patent with application number CN201920047081.9, entitled "A Dual-Furnace Integrated Core Rod Sintering Device", discloses the use of a dehydration furnace and a sintering furnace to control different heating zones for sintering. However, for large-sized bright rods, the dual-furnace sintering equipment occupies a large space and has a higher production cost than single-furnace production. Utility Model Content

[0004] The purpose of this invention is to provide an optical fiber preform sintering device that can effectively improve the phenomenon of incomplete sintering of optical fiber preforms and occupy less space.

[0005] This utility model is implemented by the following technical solution: an optical fiber preform sintering device, comprising an outer furnace body and an inner furnace core tube; the top of the outer furnace body is provided with an opening, the inner furnace core tube passes through the opening and is placed inside the outer furnace body, the top edge of the inner furnace core tube is integrally formed with a raised edge, the raised edge is in sealing contact with the edge of the opening; a plurality of heating elements are fixed to the inner wall of the outer furnace body by connectors, each heating element is arranged sequentially along the length direction of the inner furnace core tube; a sealing cover is installed on the top of the outer furnace body covering the opening, a connecting rod is sealed through the sealing cover; an outer furnace exhaust pipe is connected to the side wall of the outer furnace body, an inner furnace exhaust pipe is connected to the sealing cover, and an air inlet pipe is connected to the bottom of the inner furnace core tube, the air inlet pipe is sealed through the outer furnace body.

[0006] Furthermore, an external furnace pressure monitoring gauge is installed on the external furnace exhaust pipe, and an internal furnace pressure monitoring gauge is installed on the internal furnace exhaust pipe.

[0007] Furthermore, an annular groove is formed on the top of the outer furnace body along the edge of the opening, and a sealing ring is provided in the groove, with the bottom surface of the protruding edge abutting against the sealing ring.

[0008] Furthermore, the structure of the heating element is a ring-shaped heating plate, and each heating element is electrically connected to a temperature controller.

[0009] Furthermore, each heating element corresponds to a set of connecting members evenly distributed along the inner circumference of the outer furnace body. Each set of connecting members includes a cantilever support rod, an arc-shaped heat insulation plate, and a support plate. One end of the cantilever support rod is vertically fixed to the inner wall of the outer furnace body, and the other end of the cantilever support rod is fixed to the back of the arc-shaped heat insulation plate. The arc surface of the arc-shaped heat insulation plate matches the corresponding heating element. The bottom end of the arc-shaped heat insulation plate is hinged to the support plate through a pin. A torsion spring is sleeved on the pin. The two ends of the torsion spring abut against the bottom surface of the support plate and the back of the arc-shaped heat insulation plate, respectively. The top surface of the support plate contacts the corresponding heating element.

[0010] Advantages of this utility model: (1) The heating elements of this utility model can make the preformed brittle body sinter evenly and improve the poorly sintered areas of the preformed brittle body; (2) The sintering equipment of this utility model is a vacuum furnace that integrates dehydration and sintering functions, which reduces the space occupied by the furnace body compared with the traditional double furnace structure; (3) In the production process, compared with the traditional double furnace structure, the preformed brittle body needs to be moved alternately between the dehydration zone and the sintering zone, while this utility model does not need to move the preformed brittle body, which further increases the sintering efficiency. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model.

[0012] Figure 2 for Figure 1 A magnified view of part A.

[0013] Figure 3 This is a diagram showing the state changes of the preformed bar porous body during sintering.

[0014] The components in the attached diagram are labeled as follows: outer furnace body 1, opening 1.1, groove 1.2, sealing ring 1.3, inner furnace core tube 2, raised edge 2.1, connector 3, cantilever support rod 3.1, arc-shaped heat insulation plate 3.2, support plate 3.3, pin shaft 3.4, torsion spring 3.5, heating element 4, sealing cover 5, connecting rod 6, outer furnace exhaust pipe 7, inner furnace exhaust pipe 8, air inlet pipe 9, outer furnace pressure monitoring gauge 10, inner furnace pressure monitoring gauge 11, precast bar loose body 12. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "front", "rear", "top", "bottom", "left", "right", "vertical", "horizontal", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0017] like Figure 1 and Figure 2 As shown, this embodiment provides an optical fiber preform sintering device, which includes an outer furnace body 1 and an inner furnace core tube 2. The top of the outer furnace body 1 is provided with an opening 1.1, and the inner furnace core tube 2 passes through the opening 1.1 and is placed inside the outer furnace body 1. The top edge of the inner furnace core tube 2 is integrally formed with a raised edge 2.1, which is in sealing contact with the edge of the opening 1.1. In this embodiment, the top of the outer furnace body 1 is provided with an annular groove 1.2 along the edge of the opening 1.1, and a sealing ring 1.3 is provided in the groove 1.2. The bottom surface of the raised edge 2.1 abuts against the sealing ring 1.3. This makes the outer furnace body 1 and the inner furnace core tube 2 form two independent cavities, and the inner furnace core tube 2 provides a sintering environment for the porous preform.

[0018] A sealing cover 5 is installed on the top of the outer furnace body 1, covering the opening 1.1. A connecting rod 6 is sealed through the sealing cover 5. The top handle of the preformed briquettes is inverted conical, and the bottom end of the connecting rod 6 is forked. The top handle of the preformed briquettes can be movably hooked onto the bottom end of the forked connecting rod 6. The connecting rod 6 is clamped by the existing lifting mechanism, and the hooked preformed briquettes are slowly fed into the inner furnace core tube 2. After the preformed briquettes are fed into the predetermined position, the sealing cover 5 is tightened.

[0019] A plurality of heating elements 4 are fixed to the inner wall of the outer furnace body 1 by connectors 3. Each heating element 4 corresponds to a set of connectors 3 evenly distributed along the circumference of the inner wall of the outer furnace body 1. In this embodiment, each set includes two symmetrical connectors 3. The connectors 3 include a cantilever support rod 3.1, an arc-shaped heat insulation plate 3.2, and a support plate 3.3. One end of the cantilever support rod 3.1 is vertically fixed to the inner wall of the outer furnace body 1, and the other end of the cantilever support rod 3.1 is fixed to the back of the arc-shaped heat insulation plate 3.2. The arc surface of the arc-shaped heat insulation plate 3.2 matches the corresponding heating element 4. The bottom end of the arc-shaped heat insulation plate 3.2 is hinged to the support plate 3.3 by a pin 3.4. A torsion spring 3.5 is sleeved on the pin 3.4. The two ends of the torsion spring 3.5 abut against the bottom surface of the support plate 3.3 and the back of the arc-shaped heat insulation plate 3.2, respectively. The top surface of the support plate 3.3 contacts the corresponding heating element 4. Under the action of the torsion spring 3.5, the support plate 3.3 can support the heating element 4 and limit its position. The support plate 3.3 is flipped downward around the pin 3.4 to facilitate the placement of the lower heating element 4. Each heating element 4 is arranged sequentially along the length of the inner furnace core tube 2. In this embodiment, the structure of the heating element 4 is an annular heating plate. Each heating element 4 is electrically connected to a temperature controller, and the working temperature of each heating element 4 is controlled by the temperature controller.

[0020] The outer furnace body 1 is connected to an outer furnace exhaust pipe 7 on its side wall, and an inner furnace exhaust pipe 8 is connected to the sealing cover 5. The outer furnace exhaust pipe 7 and the inner furnace exhaust pipe 8 are connected to a vacuum pump. The bottom of the inner furnace core tube 2 is connected to an air inlet pipe 9, which is sealed and extends out of the outer furnace body 1. Process gas is introduced through the air inlet pipe 9. An outer furnace pressure monitoring gauge 10 is installed on the outer furnace exhaust pipe 7, and an inner furnace pressure monitoring gauge 11 is installed on the inner furnace exhaust pipe 8. During production, the gas in the inner furnace core tube 2 and the outer furnace body 1 is discharged through the inner furnace exhaust pipe 8 and the outer furnace exhaust pipe 7. The air inlet pipe 9 supplies the process gas required for production. The pressure status in the corresponding inner furnace core tube 2 and outer furnace body 1 is monitored in real time through the inner furnace pressure monitoring gauge 11 and the outer furnace pressure monitoring gauge 10 to ensure the stability of the pressure difference between the inner and outer furnace bodies 1.

[0021] Work process:

[0022] (1) Turn on the vacuum pump, and the inner furnace core tube and outer furnace body are in a vacuum environment;

[0023] (2) When the vacuum degree of the inner furnace core tube and the outer furnace body is evacuated to 10~500pa, all heating elements are controlled to ensure that the temperature rises to the standby temperature of 800℃~1000℃ at a rate of 1~20℃ / min. At the same time, N2, Cl2 or argon gas is introduced into the gas inlet pipe to keep the vacuum degree at 10~500pa.

[0024] (3) The heating elements are numbered and named sequentially from bottom to top: #1, #2, #3, ~, #n;

[0025] (4) First, heat the #1 heating element to 1300℃~1400℃ at a rate of 1~20℃ / min for sintering, and heat the #2 heating element to 1000℃~1200℃ at a rate of 1~20℃ / min for dehydration, and hold for 30~180min.

[0026] (5) Then heat the #2 heating element to 1300℃~1400℃ at a rate of 1~20℃ / min, cool the #1 heating element to 1000℃~1200℃ at a rate of 1~20℃ / min, and heat the #3 heating element to 1000℃~1200℃ at a rate of 1~20℃ / min, and hold for 30~180min;

[0027] (6) Continue in this manner until all temperature zones #1, #2, #3, ~, #n have been heated to 1300℃~1400℃ and maintained at 1000℃~1200℃;

[0028] (7) After the preformed porous body has been vitrified, a pressurization process is carried out by introducing N2, Cl2 or argon into the inlet pipe until the pressure inside the inner furnace core tube and the outer furnace body is at normal atmospheric pressure. The sintering is then completed. The state change diagram of the preformed porous body during the sintering process is shown in the figure below. Figure 3 As shown.

[0029] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A fiber optic preform sintering device, characterized in that, It includes the outer furnace body and the inner furnace core tube; The top of the outer furnace body is provided with an opening, and the inner furnace core tube passes through the opening and is placed inside the outer furnace body. The top edge of the inner furnace core tube is integrally formed with a raised edge, and the raised edge is in sealing contact with the edge of the opening. The inner wall of the outer furnace body is fixed with several heating elements by connectors, and each heating element is arranged sequentially along the length of the inner furnace core tube; a sealing cover is installed on the top of the outer furnace body covering the opening, and a connecting rod is sealed through the sealing cover; The outer furnace body is connected to an outer furnace exhaust pipe on its side wall, and an inner furnace exhaust pipe is connected to the sealing cover. The bottom of the inner furnace core tube is connected to an air inlet pipe, and the air inlet pipe passes through the outer furnace body in a sealed manner.

2. The optical fiber preform sintering equipment according to claim 1, characterized in that, An external furnace pressure monitoring gauge is installed on the external furnace exhaust pipe, and an internal furnace pressure monitoring gauge is installed on the internal furnace exhaust pipe.

3. The optical fiber preform sintering equipment according to claim 1, characterized in that, The top of the outer furnace body has an annular groove along the edge of the opening, and a sealing ring is provided in the groove. The bottom surface of the convex edge abuts against the sealing ring.

4. The optical fiber preform sintering equipment according to any one of claims 1 to 3, characterized in that, The heating element has a ring-shaped heating plate structure, and each heating element is electrically connected to a temperature controller.

5. The optical fiber preform sintering equipment according to claim 4, characterized in that, Each heating element corresponds to a set of connectors evenly distributed along the inner circumference of the outer furnace body. Each set of connectors includes a cantilever support rod, an arc-shaped heat insulation plate, and a support plate. One end of the cantilever support rod is vertically fixed to the inner wall of the outer furnace body, and the other end of the cantilever support rod is fixed to the back of the arc-shaped heat insulation plate. The arc surface of the arc-shaped heat insulation plate matches the corresponding heating element. The bottom end of the arc-shaped heat insulation plate is hinged to the support plate by a pin. A torsion spring is sleeved on the pin. The two ends of the torsion spring abut against the bottom surface of the support plate and the back of the arc-shaped heat insulation plate, respectively. The top surface of the support plate contacts the corresponding heating element.

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