Optical fiber preform loose body integrated sintering furnace and sintering method thereof

Abstract

The invention discloses an optical fiber preform loose body integrated sintering furnace and a sintering method thereof.The sintering furnace comprises a laser transceiver, a quartz furnace core tube and a sintering furnace body, the sintering furnace body comprises an upper sintering furnace body and a lower sintering furnace body which are concentrically arranged, and the quartz furnace core tube is concentrically arranged in the sintering furnace body; an air inlet is formed below the quartz furnace core tube, and an air outlet is formed above the quartz furnace core A sintering guide rod is arranged in the center of the quartz furnace core tube, and matched fixing devices are respectively arranged on the quartz furnace core tube and the sintering guide rod; the laser transceivers are arranged at the top end of the upper sintering furnace and an inlet of the quartz furnace core tube. The optical fiber preform loose body integrated sintering furnace designed in the scheme is of an up-down double-sintering structure which is arranged up and down, the structure is simple, space saving is facilitated, the lower half section can be sintered while the upper half section of the sintering furnace conducts dehydration, and meanwhile the effects of saving cost and simplifying the production process are achieved.

Description

Technical Field

[0001] The invention relates to an optical fiber preform loose body integrated sintering furnace and a sintering method thereof, belonging to the technical field of optical fibers. Background Art

[0002] Optical fiber preform is the basic material for manufacturing optical fiber. Its internal refractive index can effectively control the propagation of light, and its structure directly determines the final transmission performance of the optical fiber. With the development of optical fiber technology, its preparation precision is getting higher and higher. At present, it is generally prepared by a two-step method. Specifically, the core rod is prepared first, and then the cladding is deposited or the sleeve is set outside the core rod; the deposition of the cladding generally adopts the axial vapor deposition method or the external vapor deposition method. Both schemes involve dehydration and sintering processes and annealing and degassing processes. The specific function of the dehydration and sintering process is to convert the low-density and opaque core rod loose body into a densified and transparent glass body through high temperature. The annealing and degassing process uses the thermal diffusion principle of gas at high temperature to remove microbubbles in the core rod. The former process is related to whether the optical fiber preform is a low water peak optical fiber preform, and the latter process is related to the toughness and diameter fluctuation during the optical fiber drawing process. Both are indispensable.

[0003] The mainstream process used in the industry is a three-stage design of dehydration-sintering-annealing and degassing to ensure that each step has sufficient reaction time.

[0004] There are three problems in this process: first, there are too many equipments, which requires a very large plant area for equipment layout, occupying a large area and with too high cost; second, the working hours between each circulation link are too long, and the overall duration of a typical process is between 35 and 42 hours, which seriously affects production efficiency; third, the recovery rate of the high-cost helium used in the annealing and degassing link is too low, resulting in an increase in the overall cost of the production process.

[0005] In order to improve efficiency, the Chinese patent application number 2018221531108 connected dehydration and sintering and designed a dehydration and sintering furnace with an upper and lower structure. However, it failed to achieve precise control of the sintering time of the upper and lower furnaces. In addition, due to the complexity of the preparation process, the optical fiber preform often has too many bubbles in the process control deviation during the production process, making it impossible to stretch. This phenomenon seriously affects the product yield.

[0006] The optical fiber preform industry is an asset-heavy industry, with large land area, many equipments and long production cycle, which puts great pressure on the company's cash flow. In the preparation process of optical fiber preform, the mainstream is:

[0007] In the dehydration and sintering process, the loose body is generally dehydrated at a speed of 10-12mm / min, then sintered at a speed of 3-4mm / min, and then the sintered loose body is deposited under inert gas protection for 22-26h. In this process, the sintering furnace needs to be preheated before dehydration and sintering. During the deposition process after sintering, the sintering furnace is generally on standby, and its standby temperature is generally 800℃, which requires a lot of energy to maintain. How to handle the connection between processes and utilize the time difference between sintering and deposition has become a key issue that needs to be solved to improve enterprise productivity. Summary of the invention

[0008] The object of the present invention is to provide an optical fiber preform loose body integrated sintering furnace and a sintering method thereof to solve the technical problems in the above background.

[0009] The technical solution of an integrated sintering furnace for a loose body of an optical fiber preform to achieve the purpose of the present invention is:

[0010] It includes a laser transceiver, a quartz furnace core tube, and a sintering furnace, wherein the sintering furnace includes an upper sintering furnace and a lower sintering furnace which are arranged concentrically, and the quartz furnace core tube is arranged concentrically in the sintering furnace;

[0011] The quartz furnace core tube is provided with an air inlet at the bottom and an air outlet at the top;

[0012] A sintering guide rod is provided at the center of the quartz furnace core tube, and matching fixing devices are provided on the quartz furnace core tube and the sintering guide rod respectively;

[0013] The laser transceiver is arranged at the top of the upper sintering furnace and the entrance of the quartz furnace core tube.

[0014] In the above structure, the gas introduced into the air inlet is chlorine, oxygen, helium and other process gases; the air outlet is provided with an exhaust device to extract the waste gas to the waste gas treatment system.

[0015] When in use, the core rod loose body is placed from the upper sintering furnace and moves longitudinally under the traction of the sintering guide rod. The core rod loose body passes through the upper sintering furnace and the lower sintering furnace successively. The laser transceiver is used to control its descending height, sintering temperature and sintering time. At the same time, gas is introduced from the air inlet. After maintaining for a period of time, the sintering dehydration process and the annealing degassing process can be completed. After preparation is completed, the core rod can be taken out from the quartz furnace core tube.

[0016] The above-mentioned structure of an integrated sintering furnace for loose bodies of optical fiber preform rods has an upper and lower double sintering structure, which is arranged up and down with a simple structure, which is conducive to saving space; while the upper half of the sintering furnace is dehydrating, the lower half can be sintered at the same time, the upper sintering furnace and the lower sintering furnace can be connected, and the lower sintering furnace has a fast heating speed, which is conducive to increasing the sintering speed and improving production efficiency; the lower sintering furnace in the structure can also have a degassing function, and can be directly degassed after sintering is completed, saving degassing equipment.

[0017] The optical fiber preform loose body integrated sintering furnace designed in this scheme has the functions of saving costs and simplifying the production process.

[0018] Further or optionally, in order to better fix the sintering lead rod in the quartz furnace core tube, the matching fixing device is at least a second-order flange, a quartz ring and a connecting sleeve, wherein the flange is arranged above the quartz furnace core tube and matches it, the connecting sleeve is arranged below the sintering lead rod, the quartz ring is divided into a flange quartz ring and a connecting sleeve quartz ring, the flange quartz ring is vertically fixedly connected to the sintering lead rod and matches the first-order inner ring of the flange away from the sintering lead rod, and the connecting sleeve quartz ring is arranged above the connecting sleeve and matches the inner diameter gap of the quartz furnace core tube.

[0019] When in use, hang the core rod loose body on the connecting sleeve, then place the flange quartz ring in the flange, and put the connecting sleeve quartz ring into the quartz furnace core tube. Pay attention to prevent the core rod loose body from falling vertically during the process. When the connecting sleeve quartz ring touches the quartz furnace core tube, adjust it in time to avoid severe friction between the two and damage to the quartz furnace core tube.

[0020] Further or optionally, in order to obtain a better sealing effect, the flange is a three-step flange, and the flange quartz ring is divided into a first flange quartz ring and a second flange quartz ring. The first step of the flange matches the first quartz ring, the second step matches the second quartz ring, and the third step is the same as the inner diameter of the quartz furnace core tube.

[0021] When in use, directly connect the third step of the flange to the quartz furnace core tube, and cover the second flange quartz ring at the opening of the quartz furnace core tube to seal it.

[0022] In all the above flange and quartz ring structures, the surface of the quartz ring is frosted material, the outer diameter of the quartz ring of the first flange is 400mm, the outer diameter of the quartz ring of the second flange is 320mm, and the outer diameter of the quartz ring of the connecting sleeve is 260mm; the inner diameter of the first step of the flange is 450mm, the inner diameter of the second step is 360mm, and the inner diameter of the third step is the same as the inner diameter of the quartz furnace core tube, both of which are 300mm.

[0023] Further or optionally, in order to make the heating temperature more uniform and extend the life of the sintering furnace, the sintering furnace has a graphite heating element prepared by a static pressing molding process. Specifically, the height of the graphite heating element of the upper sintering furnace is 400mm; the height of the graphite heating element of the lower sintering furnace is 800mm.

[0024] The present invention also provides an integrated sintering method for a loose body of an optical fiber preform, which uses the above-mentioned sintering furnace to work, and specifically comprises the following steps:

[0025] S1: lift the sintering guide rod to the top of the quartz furnace core tube, hang the core rod loose body on the sintering guide rod, and adjust the straightness to ensure that the sintering guide rod drives the core rod loose body to rotate without hitting the side wall of the quartz furnace core tube;

[0026] S2: lower the sintering guide rod until the core rod loose body reaches the upper end of the upper sintering furnace;

[0027] S3: The sintering furnace is heated up, chlorine and oxygen are charged from the lower air inlet, and the sintering guide rod is rotated and descended;

[0028] S4: When the upper end of the core rod loose body is flush with the upper end of the lower sintering furnace, the oxygen is turned off and helium and chlorine are introduced instead, while the sintering guide rod continues to descend;

[0029] S5: When the upper part of the core rod loose body is flush with the heating element of the lower sintering furnace, the sintering guide rod stops descending and keeps the temperature unchanged for a certain period of time;

[0030] S6: The upper sintering furnace and the lower sintering furnace are cooled down, and the core rod loose body remains still in the sintering furnace for a certain period of time.

[0031] Further or optionally, in order to make the sintering effect more dense and transparent, in step S3, the temperature of the upper sintering furnace is 1100-1200° C., the temperature of the lower sintering furnace is 1500-1600° C., the chlorine flow rate is 0-1.5 L / min, and the oxygen flow rate is 0-1.2 L / min;

[0032] In step S4, the helium flow rate is 5-20 L / min, and the chlorine flow rate is 0-0.3 L / min.

[0033] Further or optionally, in order to make the sintering more uniform, the rotation speed of the sintering guide rod in step S3 is 3-8 rpm, and the descending speed is 8-18 mm / min;

[0034] In step S4, the sintering guide rod descends at a speed of 3-8 mm / min.

[0035] Further or optionally, in order to make the degassing more complete, the temperature is maintained for 5-10 minutes in step S5.

[0036] Further or optionally, in order to obtain a better deposition effect, in the step S6, the upper sintering furnace is cooled to 1150° C., the lower sintering furnace is cooled to the standby temperature, and the core rod loose body is stationary for 8-14 hours.

[0037] By adopting the above technical solution, the present invention has the following beneficial effects:

[0038] (1) The present invention discloses an integrated sintering furnace for optical fiber preform loose body, which has an upper and lower double-sintering structure. The structure is simple and is conducive to saving space. While the upper half of the sintering furnace is dehydrating, the lower half can be sintered at the same time. The upper sintering furnace and the lower sintering furnace can be connected, and the lower sintering furnace has a fast heating speed, which is conducive to increasing the sintering speed and improving production efficiency. The lower sintering furnace in the structure can also have a degassing function, and can be directly degassed after sintering, saving degassing equipment and degassing process. In general, the present invention discloses an integrated sintering furnace for optical fiber preform loose body, which has the functions of saving costs and simplifying the production process. The number of bubbles can be stably controlled in the single digit, so that the scrap caused by the bubble factor is almost eliminated. And because the bubbles are effectively eliminated, the overall attenuation rate of the optical fiber is greatly reduced, which can greatly improve the communication rate of the optical fiber. By adopting this scheme, the number of bubbles can be stably controlled in the single digit, so that the scrap caused by the bubble factor is almost eliminated. And because the bubbles are effectively eliminated, the overall attenuation rate of the optical fiber is greatly reduced, which can greatly improve the communication rate of the optical fiber.

[0039] (2) The optical fiber preform loose body integrated sintering furnace of the present application is provided with a flange, a quartz ring and a connecting sleeve, so that the sintering lead rod can be better fixed in the quartz furnace core tube.

[0040] (3) The optical fiber preform loose body integrated sintering furnace of the present application has an upper and lower double sintering structure and is also provided with a three-step flange structure and a second flange quartz ring with a sealing effect, which can achieve a better sealing effect.

[0041] (4) The optical fiber preform loose body integrated sintering furnace of the present application adopts a graphite heating element prepared by a static pressing molding process, which can make the heating temperature more uniform and prolong the service life of the sintering furnace.

[0042] (5) The present application also provides a method for integrated sintering of a loose body of an optical fiber preform rod, which effectively utilizes the time difference between the deposition process and the sintering process for producing a unit product, eliminates the separate degassing process, flow and equipment, reduces the idle time of equipment, increases the equipment start-up rate, improves production efficiency, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein

[0044] Figure 1 It is a structural schematic diagram of the present invention.

[0045] The numbers in the accompanying drawings are: laser transceiver 1, quartz furnace core tube 2, air inlet 21, air outlet 22, sintering furnace 3, upper sintering furnace 31, lower sintering furnace 32, sintering guide rod 4, flange 5, quartz ring 6, flange quartz ring 61, first flange quartz ring 611, second flange quartz ring 612, connecting sleeve quartz ring 62, connecting sleeve 7. DETAILED DESCRIPTION

[0046] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0050] In the description of the embodiments of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when used, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present invention is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0052] See Figure 1 The optical fiber preform loose body integrated sintering furnace of this embodiment includes a laser transceiver 1, a quartz furnace core tube 2, and a sintering furnace 3. The sintering furnace 3 includes an upper sintering furnace 31 and a lower sintering furnace 32 which are concentrically arranged. The quartz furnace core tube 2 is concentrically arranged in the sintering furnace 3.

[0053] The quartz furnace core tube 2 is provided with an air inlet 21 at the bottom and an air outlet 22 at the top;

[0054] A sintering guide rod 4 is provided at the center of the quartz furnace core tube 2, and matching fixing devices are provided on the quartz furnace core tube 2 and the sintering guide rod 4 respectively;

[0055] The laser transceiver 1 is arranged at the top of the upper sintering furnace 31 and at the entrance of the quartz furnace core tube 2 .

[0056] The matching fixing device is a flange 5, a quartz ring 6 and a connecting sleeve 7 of at least two levels, wherein

[0057] The flange 5 is arranged above the quartz furnace core tube 2 and matches it, the connecting sleeve 7 is arranged below the sintering lead rod 4, the quartz ring 6 is divided into a flange quartz ring 61 and a connecting sleeve quartz ring 62, the flange quartz ring 61 is vertically fixedly connected to the sintering lead rod 4 and matches the first-order inner ring of the flange 5 away from the sintering lead rod 4, and the connecting sleeve quartz ring 62 is arranged above the connecting sleeve 7 and matches the inner diameter gap of the quartz furnace core tube 2.

[0058] The flange 5 is a three-step flange, and the flange quartz ring 61 is divided into a first flange quartz ring 611 and a second flange quartz ring 612 . The first step of the flange 5 matches the first quartz ring 611 , the second step matches the second quartz ring 612 , and the third step is the same as the inner diameter of the quartz furnace core tube 2 .

[0059] The sintering furnace 3 has a graphite heating element prepared by a static pressing process.

[0060] The above-mentioned method for integrated sintering of an optical fiber preform loose body is used to prepare an optical fiber preform loose body, which specifically includes the following three embodiments:

[0061] (Example 1)

[0062] Lift the sintering guide rod 4 to 2m above the flange 5, hang the core rod loose body to the connecting sleeve 7 below the sintering guide rod 4, and adjust the straightness so that the loose body will not touch the inner wall of the quartz furnace core tube 2 when rotating;

[0063] The sintering guide rod 4 is lowered. When the tip of the lower part of the core rod loose body blocks the laser transceiver 1, its initial point is recorded. The sintering guide rod 4 continues to descend until it stops descending when it descends to the distance where the core rod loose body is located at the upper end of the heating element of the upper sintering furnace 31. At this time, the first flange quartz ring 611 has fallen on the first step position of the flange 5, and the second flange quartz ring 612 has fallen on the second step position of the flange 5, completing the sealing of the upper sintering furnace 31. At the same time, the upper sintering furnace 31 begins to heat up to 1100°C, and the lower sintering furnace 32 begins to heat up to 1500°C. The lower air inlet 22 begins to introduce 1.1L / min of chlorine and 0.6L / min of oxygen. After reaching the target temperature, the sintering guide rod 4 rotates at a speed of 3rpm and begins to descend at a speed of 8mm / min until. The lower tip of the core rod loose body is flush with the graphite heating element of the lower sintering furnace 32, and the descending speed is changed to 8mm / min. It continues to descend until the upper diameter-changing area of ​​the core rod loose body is flush with the upper end of the graphite heating element of the upper sintering furnace 31. Then, the oxygen is turned off, and 15L / min of helium and 0.22L / min of chlorine are introduced until the upper diameter-changing area of ​​the core rod loose body is flush with the upper end of the graphite heating element of the lower sintering furnace 32. The sintering guide rod 4 no longer descends, and this state is maintained for 5 minutes. The helium flow rate is changed to 2L / min, the temperature of the lower sintering furnace 32 is reduced to 1150°C, and the upper sintering furnace 32 is cooled to the standby temperature (800°C). The sintering guide rod 4 is kept rotating and enters the degassing state. After maintaining this state for 10 hours, the transparent core rod can be taken out of the sintering furnace 3 and transferred to the subsequent process.

[0064] The time consumed in the whole process (including the time of heating and cooling) is 19 hours, and the time consumed for depositing the loose body is 22 hours, with a time difference of 3 hours.

[0065] The number of bubbles inside the drawn core rod after the subsequent drawing process and the related parameters after being drawn into optical fiber are as follows:

[0066] Number of bubbles with a diameter greater than 2 mm 1383nm attenuation 3pcs / m 0.302dB / km

[0067] (Example 2):

[0068] Different from Example 1, the sintering furnace 3 used is a single sintering furnace. The dehydration process is carried out first, and then the core rod loose body is lifted above the heating element and then the heating and sintering processes are carried out. The upper sintering furnace 31 starts to heat up to 1200°C, and the lower sintering furnace 32 starts to heat up to 1600°C. The sintering guide rod 4 rotates at a speed of 8rpm, and the sintering guide rod 4 descends at a speed of 18mm / min during dehydration and 3.5mm / min during sintering. It is then transferred to the degassing process for a degassing process at 1150°C and 10h.

[0069] The process consumes 14 hours of time in the dehydration and sintering stage, while the loose body deposition time is 23 hours, with a time difference of 9 hours. In addition, the subsequent degassing requires 10 hours, resulting in a total waste of 19 hours.

[0070] The number of bubbles inside the stretched core rod after stretching and the related parameters after being drawn into optical fiber are as follows:

[0071] Number of bubbles with a diameter greater than 2 mm 1383nm attenuation 4pcs / m 0.304dB / km

[0072] (Example 3)

[0073] Unlike Example 2, it does not go through the degassing process in the later process. The parameters related to the number of bubbles inside the drawing mandrel after drawing are as follows (since there are too many bubbles, subsequent wire drawing will inevitably cause continuous tower breaks, so there is no need for wire drawing):

[0074] Number of bubbles with a diameter greater than 2 mm 1383nm attenuation 22pcs / m No wire drawing

[0075] It can be clearly seen that the use of the sintering furnace and the sintering method in the first embodiment can effectively save a separate degassing process, and can effectively utilize the time difference between dehydration sintering and deposition, so as to improve production efficiency and reduce production costs. In addition, the quality of the product produced is almost the same as that of the product produced by using a traditional single sintering furnace for dehydration sintering and subsequent degassing process.

[0076] From the test data, we can see that the adoption of the above technical solution can also greatly reduce the number of bubbles in the optical fiber and optimize the attenuation rate after core rod drawing. The number of bubbles after fiber formation can be as low as 4 / m, and the attenuation at 1383nm can be as low as 0.304dB / km. The number of bubbles can be stably controlled in single digits, making the scrap caused by bubbles almost eliminated; and because bubbles are effectively eliminated, the overall attenuation rate of the optical fiber is greatly reduced, which can greatly improve the communication rate of the optical fiber.

[0077] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated sintering furnace for loose bodies of optical fiber preforms, characterized in that: It comprises a laser transceiver (1), a quartz furnace core tube (2), and a sintering furnace (3), wherein the sintering furnace (3) comprises an upper sintering furnace (31) and a lower sintering furnace (32) which are arranged concentrically, and the quartz furnace core tube (2) is concentrically arranged in the sintering furnace (3); The quartz furnace core tube (2) is provided with an air inlet (21) at the bottom and an air outlet (22) at the top; A sintering guide rod (4) is provided at the center of the quartz furnace core tube (2), and matching fixing devices are provided on the quartz furnace core tube (2) and the sintering guide rod (4); The laser transceiver (1) is arranged at the top of the upper sintering furnace (31) and at the entrance of the quartz furnace core tube (2).

2. The optical fiber preform loose body integrated sintering furnace according to claim 1, characterized in that: The matching fixing device is a flange (5) with at least two levels, a quartz ring (6) and a connecting sleeve (7), wherein The flange (5) is arranged above the quartz furnace core tube (2) and matches the same; the connecting sleeve (7) is arranged below the sintering guide rod (4); the quartz ring (6) is divided into a flange quartz ring (61) and a connecting sleeve quartz ring (62); the flange quartz ring (61) is vertically fixedly connected to the sintering guide rod (4) and matches the first-order inner ring of the flange (5) away from the sintering guide rod (4); the connecting sleeve quartz ring (62) is arranged above the connecting sleeve (7) and matches the inner diameter gap of the quartz furnace core tube (2).

3. The optical fiber preform loose body integrated sintering furnace according to claim 1, characterized in that: The flange (5) is a three-step flange, and the flange quartz ring (61) is divided into a first flange quartz ring (611) and a second flange quartz ring (612). The first step of the flange (5) matches the first quartz ring (611), the second step matches the second quartz ring (612), and the third step has the same inner diameter as the quartz furnace core tube (2).

4. The optical fiber preform loose body integrated sintering furnace according to claim 1, characterized in that: The sintering furnace (3) has a graphite heating element prepared by a static pressing process.

5. A method for integrated sintering of a loose body of an optical fiber preform, using the sintering furnace described in any one of claims 1 to 4, specifically comprising the following steps: S1: lifting the sintering guide rod (4) to the top of the quartz furnace core tube (2), hanging the core rod loose body on the sintering guide rod (4), and adjusting the straightness to ensure that the sintering guide rod (4) drives the core rod loose body to rotate without hitting the side wall of the quartz furnace core tube (2); S2: lowering the sintering guide rod (4) until the core rod loose body reaches the upper end of the upper sintering furnace (31); S3: The sintering furnace (3) is heated up, chlorine and oxygen are charged from the lower air inlet (21), and the sintering guide rod (4) is rotated and descended; S4: When the upper end of the core rod loose body is flush with the upper end of the lower sintering furnace (32), the oxygen is turned off and helium and chlorine are introduced instead, while the sintering guide rod (4) continues to descend; S5: When the upper part of the core rod loose body is flush with the heating element of the lower sintering furnace (32), the sintering guide rod (4) stops descending and keeps the temperature constant for a certain period of time; S6: The upper sintering furnace (31) and the lower sintering furnace (32) are cooled, and the core rod loose body remains stationary in the sintering furnace (3) for a certain period of time.

6. The method for integrated sintering of a loose body of an optical fiber preform according to claim 5, characterized in that: In step S3, the temperature of the upper sintering furnace (31) is 1100-1200°C, and the temperature of the lower sintering furnace (32) is 1500-1600°C.

7. The method for integrated sintering of an optical fiber preform loose body according to claim 5, characterized in that: The chlorine flow rate is 0-1.5L / min, and the oxygen flow rate is 0-1.2L / min; In step S4, the helium flow rate is 5-20 L / min, and the chlorine flow rate is 0-0.3 L / min.

8. The method for integrated sintering of an optical fiber preform loose body according to claim 5, characterized in that: In step S3, the sintering guide rod (4) rotates at a speed of 3-8 rpm and descends at a speed of 8-18 mm / min; In the step S4, the sintering guide rod (4) descends at a speed of 3-8 mm / min.

9. The method for integrated sintering of an optical fiber preform loose body according to claim 5, characterized in that: The temperature keeping time in step S5 is 5-10 minutes.

10. The method for integrated sintering of an optical fiber preform loose body according to claim 5, characterized in that: In step S6, the upper sintering furnace (31) is cooled to 1150° C., and the lower sintering furnace (32) is cooled to the standby temperature. The static time of the core rod loose body is 8-14h.

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