CN107601840B - Sectional type optical fiber preform rod sintering furnace device and corresponding optical rod sintering method - Google Patents
Sectional type optical fiber preform rod sintering furnace device and corresponding optical rod sintering method Download PDFInfo
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- CN107601840B CN107601840B CN201711048037.1A CN201711048037A CN107601840B CN 107601840 B CN107601840 B CN 107601840B CN 201711048037 A CN201711048037 A CN 201711048037A CN 107601840 B CN107601840 B CN 107601840B
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Abstract
The invention relates to a sectional type sintering furnace device for an optical fiber preform rod and a sintering method for the optical fiber preform rod by adopting the sintering furnace device. The sintering method is characterized in that loose bodies of the optical fiber preform rod to be sintered are fixedly arranged at the lower end of a guide rod and are sent into a furnace core pipe through the guide rod for sintering. The sectional furnace core pipe provided by the invention has long service life, the furnace core pipe does not need to be replaced after the temperature is reduced to the normal temperature, the temperature can be increased again for use, and the heating section pipe body of the furnace core pipe can be independently replaced, so that the production cost is favorably reduced, and the quality of an optical fiber product is favorably improved.
Description
Technical Field
The invention relates to a sectional type sintering furnace device for an optical fiber preform rod, and also relates to a sintering method for the optical fiber preform rod (an optical rod or the preform rod for short) by adopting the sintering furnace device. Belonging to the technical field of optical fiber manufacturing.
Background
The sintering process of the loose body of the optical fiber perform rod is a key link in large-scale mass preparation of large-size optical fiber perform rods by VAD method, the sintering of the loose body of the optical fiber perform rod is carried out in a sintering furnace of the perform rod at present, the sintering furnace is provided with a furnace core pipe and a heating element surrounding the outside of a high-temperature area of the furnace core pipe, a high-temperature area is formed in the sealed furnace core pipe through the heating element, the loose body on the optical fiber perform rod is vitrified under the action of high temperature, and a negative pressure and a clean environment are usually formed in the furnace core pipe in the sintering process so as to.
The existing furnace core pipe adopts a quartz glass pipe, based on the physicochemical property of quartz glass, the furnace core pipe can generate a crystallization phenomenon in a high-temperature environment, the imbalance of crystallization at each part and the defect of local crystallization can cause unevenly distributed stress, the furnace core pipe becomes brittle, and wrinkles and cracks appear, so that external gas can enter a sintering cavity of the furnace core pipe to influence the sintering of loose bodies of an optical fiber preform, and the introduced impurities can cause the attenuation of the prepared optical fiber to be increased, thereby not only restricting the improvement of the quality of the optical fiber, but also needing to be replaced when the attenuation exceeds the allowable range, which is a main factor influencing the service life of the existing furnace core pipe.
Since the muffle tube should accommodate the preform and allow the preform to move in its inner cavity, the muffle tube is larger in size than the preform, and the sealing problem due to the increased size of the muffle tube is more significant for sintering large-sized optical fiber preforms. In the background of the prior art, a large-size furnace core pipe is generally welded by a plurality of sections of quartz glass pipes, so that the requirement on the manufacturing process is high, the manufacturing cost is high, and the service life of the furnace core pipe is an important factor influencing the production cost. In addition, the replacement of the furnace core tube also affects the stability of the system, requires long-time system debugging, and also affects the production efficiency and the production cost.
Disclosure of Invention
In order to solve the technical problems, the invention provides a sectional type optical fiber perform sintering furnace device and an optical fiber perform sintering method adopting the sintering furnace device.
The technical scheme of the invention is as follows: the utility model provides a sectional type optical fiber perform sintering furnace device, includes furnace core pipe and the guide bar that can reciprocate, furnace core pipe mainly comprises last body, heating section body and lower body, go up the body and adopt quartz glass pipe with lower body, the heating section body adopts the high temperature resistant pipe body of being made by high temperature resistant material, go up the body and adopt releasable connection mode fixed mounting respectively with lower body the up end and the terminal surface of heating section body, with heating section body interconnect becomes complete furnace core pipe, the outside of heating section body is equipped with the sealed chamber that encircles this body, be equipped with the heating member in the sealed chamber, the mount frame of guide bar is located the top of furnace core pipe, the guide bar is equipped with and drives its guide bar drive arrangement who reciprocates and encircle the rotation of axis.
The quantity of heating member is one or more, and the ring is around the middle part outside of heating section body, works as when the quantity of heating member is a plurality of, can divide into one deck or multilayer in the axial, and a plurality of heating members on the same layer are along circumference evenly distributed, works as when the heating member quantity is one, preferably is the ring around the shape in the middle part outside of heating section body.
The pin drive may be of any suitable known technology, for example, a feed and rotation device similar to a drilling machine or the like may be used.
The motor of the guide rod driving device is preferably a servo motor.
Preferably, the upper tube body and the lower tube body are connected with the heating section tube body in a detachable connection mode through sealing connectors, the sealing connectors can adopt any suitable existing technology, for example, a sleeve can be arranged, the connecting ends of the two tube bodies to be connected are respectively inserted into the sleeve from two ends of the sleeve, the fit clearance between the connecting ends and the inner wall of the sleeve is small enough, or high-temperature-resistant sealing materials are filled in the clearance between the connecting ends and the inner wall of the sleeve, so that fixed connection and sealing are achieved at the same time.
The upper pipe body and the lower pipe body can be respectively provided with respective furnace core pipe ventilation pipes so as to be respectively used for air inlet and outlet of the inner cavity of the furnace core pipe, and the specific air inlet and outlet flow direction can be according to actual requirements.
The upper end of the furnace core pipe can be provided with a sealing end cover for sealing a port and a sealing cover positioned on the sealing end cover, the sealing end cover is fixed at the upper end of the furnace core pipe in a detachable connection manner (for example, the sealing end cover is buckled at the upper end of the furnace core pipe, the upper end of the furnace core pipe can be provided with a matching structure such as an annular tongue-and-groove which is used for matching with the sealing end cover so as to be beneficial to the positioning and fixing of the sealing end cover), and the sealing cover is installed at the upper end of the furnace core pipe in a detachable connection manner and/or the top cover of the sealing cover is an openable top cover (for example, a cover buckled on the side wall of the sealing cover or a cover which is.
When the sealing end cover adopts two parts which can be oppositely combined and the top cover of the sealing cover is an openable top cover, the two parts of the sealing end cover are preferably equal in size and are in mirror symmetry, wherein the size of any one part is smaller than the size of the sealing cover in the horizontal direction, namely the two parts of the sealing end cover are allowed to be placed into the bottom of the sealing cover through the top opening of the sealing cover to cover the upper end port of the furnace core pipe positioned at the bottom of the sealing cover.
Because the diameter of the prefabricated rod is larger than that between the guide rods, the size of the guide rod hole is not too large, and the prefabricated rod cannot enter the furnace core tube through the guide rod hole, the sealing end cover preferably adopts a split structure, and is at least divided into two parts (for example, two semicircular rings which can be mutually matched into a circular ring) which can be mutually matched and a guide rod hole for the guide rod to pass through is reserved at the matching position. Therefore, the sealing end cover and the sealing cover can be arranged or detached under the condition that the guide rod is not moved out, the guide rod penetrates through a guide rod hole formed after the guide rod is closed, the sealing end cover is detached, the top cover of the sealing cover is opened or the sealing cover is detached, and the preform rod can directly enter the furnace core pipe through the upper end port of the furnace core pipe.
The end face sealing cover can be provided with a sealing cover ventilation pipe, and the sealing cover ventilation pipe can be arranged on the side wall of the sealing cover so as to form a certain negative pressure state in the sealing cover through an air draft mode.
The outer side of the heating section pipe body can be provided with an annular surrounding sealing cavity shell, a sealing space between the sealing cavity shell and the heating section pipe body forms the sealing cavity, the sealing cavity shell is preferably a cylindrical shell, and the central parts of the upper end surface and the lower end surface of the sealing cavity shell are respectively provided with a furnace core pipe hole for a furnace core pipe to pass through.
The sealed cavity shell can be provided with a sealed cavity ventilating pipe so as to be convenient for filling protective gas to protect the heating element and the heating section pipe body.
The detachable connection between the upper tube body and the lower tube body and the heating section tube body can adopt any connection mode suitable for multiple connection and detachment between the tube bodies, for example, one convenient and common detachable connection mode is flange connection, the other convenient and common detachable connection mode is that tongue-and-groove structures which can be mutually involutory are arranged on the connecting end faces of the two connected tube bodies, the two tube bodies are involutory through corresponding tongue-and-groove structures, even the plane end faces of the two connected tube bodies can be involutory, the other convenient detachable connection mode is that the two tube bodies are connected through various pipeline connecting devices such as a pipe hoop or a sleeve pipe, for example, the connecting ends of the two connected tube bodies are inserted on the same connecting sleeve pipe, the relative fixation between the two connected tube bodies can adopt any suitable prior art, can be direct fixation between the two tube bodies, and can also be respectively fixed on respective or common machine frames, the sealing can be arranged between the mutually connected pipe bodies according to the prior art, the sealing between the pipe bodies can adopt the hard sealing which is suitable for the corresponding high-temperature environment in consideration of the high-temperature use environment of the furnace core pipe, and the external gas can be prevented from entering by vacuumizing (negative pressure) and/or introducing protective gas and the like in the furnace core pipe under the condition that the sealing is not arranged or the sealing is not strict between the pipe bodies.
The sealing cap may be detachably connected to the top port of the muffle tube by similar or other suitable detachable connection techniques.
The high-temperature-resistant material is suitable for high-temperature resistance and corrosion resistance of the furnace core pipe, impurities are not easily introduced, the high-temperature-resistant material has required stability and reliability under the environment related to the furnace core pipe, folds and cracks of the quartz glass pipe caused by crystallization, stress unevenness and the like cannot occur, the high-temperature-resistant pipe body can be made of any suitable high-temperature-resistant material, for example, a graphite pipe body made of graphite, and an oxidation film can be plated on the graphite pipe body to further improve the performance of the high-temperature-resistant pipe body.
A sintering method of an optical fiber preform rod adopts any sectional type sintering furnace device of the optical fiber preform rod to sinter the optical fiber preform rod, loose bodies of the optical fiber preform rod to be sintered are fixedly arranged at the lower end of a guide rod, the guide rod is driven by a guide rod driving device to move downwards, the loose bodies of the preform rod are moved to an initial position set in an upper pipe body, a heating element forms required high temperature in a high-temperature sintering area in a heating section pipe body according to process requirements, the guide rod drives the loose bodies of the preform rod to enter and/or penetrate the high-temperature sintering area in the heating section pipe body to carry out high-temperature treatment under the driving of the guide rod driving device, then the loose bodies of the preform rod are returned to the initial position in the upper pipe body again, the high-temperature treatment times are one or multiple times, the loose bodies of the preform rod are enabled to realize required vitrification, the optical fiber preform rod is formed, and the preform rod is moved into the furnace core pipe from the And after the preform rod enters the furnace core pipe, the sealing end cover and the sealing cover are installed well to seal the upper port of the furnace core pipe.
Preferably, the number of high temperature treatments is two. Wherein, the first high-temperature treatment is dehydration treatment, inert protective gas (such as helium, nitrogen and the like) and chlorine used as a dehydrating agent are continuously introduced into the furnace core pipe through a furnace core pipe vent pipe arranged on the lower pipe body, so that the pressure in the furnace core pipe is in a positive pressure state (slightly higher than the atmospheric pressure of the environment), tail gas is discharged through the furnace core pipe vent pipe on the upper pipe body, the temperature of a high-temperature sintering area reaches the dehydration treatment temperature through a heating element, a guide rod moves downwards at a constant speed and rotates at a constant speed under the driving of a guide rod driving device, after a preform loose body passes through the high-temperature sintering area of the heating section pipe body, the chlorine is closed, and the dehydrated preform loose body is lifted to an initial position; the second high-temperature treatment is vitrification sintering treatment, which is carried out after the first high-temperature treatment is finished, the high-temperature sintering area is at vitrification sintering temperature when passing through a heating element, the guide rod moves downwards at a constant speed and rotates at a constant speed under the drive of the guide rod driving device, after the loose body of the prefabricated rod passes through the high-temperature sintering area of the tube body of the heating section, the guide rod moves upwards at a constant speed and rotates at a constant speed under the drive of the guide rod driving device until the vitrified prefabricated plate returns to the initial position.
The dehydration temperature and the vitrification sintering temperature are preferably 1050-1100 ℃ and 1450-1500 ℃ respectively, the downward moving speed of the guide rod in the dehydration treatment can be 3-8mm/min, the rotating speed in the downward moving process can be 3-6rpm, and the upward moving speed can be 5-10mm/min, the downward moving speed of the guide rod in the vitrification sintering treatment can be 5-10mm/min, the rotating speed in the downward moving process can be 3-6rpm, the upward moving speed can be 5-10mm/min, and the rotating speed in the upward moving process can be 3-6 rpm.
The sealing hood is preferably evacuated during all high temperature treatment.
During the whole high-temperature treatment process, the sealing cavity is preferably filled with inert gas for protection and is in a positive pressure state.
Maintenance of the furnace core tube may be performed in the following manner: when only the heating section tube body needs to be replaced, only the heating section tube body is dismantled and replaced, and the whole furnace core tube is not replaced.
The invention has the beneficial effects that: because the sectional furnace core pipe is adopted and the connection among the pipe bodies of all the sections is realized in a detachable connection mode, when the pipe bodies of the heating section cannot be continuously used, the pipe bodies of the heating section can be independently replaced without replacing the whole furnace core pipe, so that the replacement cost of the furnace core pipe is saved, the replacement operation of the pipe bodies of the heating section is simplified and facilitated while the replacement period of the furnace core pipe (the pipe bodies of the heating section) is prolonged, and the negative influence on the system caused by the replacement of the furnace core pipe is reduced; because the heating section pipe body can be made of high-temperature resistant materials, the high-temperature resistant quartz glass pipe has better thermal stability and chemical stability in the sintering process, can avoid or greatly reduce adverse changes caused by high temperature and temperature fluctuation, prolongs the service life, and simultaneously, the upper pipe body and the lower pipe body with lower environmental temperature can continuously adopt high-purity quartz glass pipes, thereby ensuring the service life, being beneficial to reducing the cost and improving the product quality; because the sealing cover adopts the components of a whole that can function independently structure and installs with the releasable connection mode, at the prefabricated stick loose body from the stove core pipe in-process that gets into the stove core pipe above, can tear the sealing cover down, can not hinder the removal of prefabricated stick loose body, and after prefabricated stick loose body gets into the stove core pipe, especially in the sintering process, can install the sealing cover on the stove core pipe, realize the sealed to the stove core pipe port, avoid influencing temperature and gas composition etc. in the stove core pipe.
Drawings
FIG. 1 is a schematic view showing the construction of a sintering furnace apparatus for a segmented optical fiber preform according to the present invention;
FIG. 2 is a schematic view of a cross-sectional A-A configuration corresponding to FIG. 1;
FIGS. 3-5 are tables showing attenuation coefficients of a G.652D conventional single-mode optical fiber manufactured by drawing a sintered optical fiber preform according to the present invention at a wavelength of 1310nm, a wavelength of 1383nm, and a wavelength of 1550nm, respectively.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in figures 1 and 2, the sintering furnace of the invention can be used for sintering loose bodies of an optical fiber preform, a furnace core tube of the sintering furnace is formed by sequentially connecting an upper tube body 10, a heating section tube body 18 and a lower tube body 20 through corresponding sealing connectors 12, the heating section tube body of the furnace core tube is made of high-temperature resistant materials and is arranged in a space surrounded by a heating element, a corresponding high-temperature area in the heating section tube body is a high-temperature sintering area 15, and the defects that the high-temperature area part of the existing integrated quartz glass furnace core tube is easy to generate crystallization and a series of faults are caused by the crystallization are overcome through the sectional design of the furnace core tube.
The upper tube body 10 and the lower tube body 20 of the furnace core tube are made of quartz glass tubes, the space 11 in the upper tube body is enough to accommodate the prefabricated rod, the initial position can be set in the upper tube body and used as the starting position of the prefabricated rod for high-temperature treatment, the heating section tube body 18 in the middle of the furnace core tube is replaceable and is connected with the upper tube body and the lower tube body in a detachable connection mode, the heating section tube body can be detached and replaced when needing to be replaced, the heating section tube body 18 is made of high-temperature-resistant materials suitable for the working condition of the furnace core tube, the sealing connecting piece between the upper tube body 10 and the lower tube body 20 which are made of the quartz glass tubes and the high-temperature-resistant heating section 18 can be in a sealing flange mode, a sealing cavity shell 19 which is annularly surrounded is arranged outside the heating section tube body 18 and the heating piece 14, and the sealing space between the, the heating member sets up in sealed chamber, and during operation, sealed chamber lets in inert gas by sealed chamber ventilation pipe 17, prevents that heating member and heating section body 18 from oxidizing, sets up pressure detector 16 on sealed chamber ventilation pipe and is used for surveying the pressure (inlet side pressure) in the sealed chamber, and inert gas gets into sealed intracavity from sealed chamber ventilation pipe 17, makes sealed chamber be in a highly compressed state (malleation state), and the outside gas of sealed chamber casing 19 can not get into in sealed chamber 13, and heating member 14 and high temperature resistant stove core pipe 18 are difficult for the oxidation.
The material of the heating section tube 18 is selected to be resistant to high temperatures and corrosion and not to introduce new impurities. The upper and lower tubular bodies 10, 20 of the sectional furnace core tube can adopt quartz glass tubes without crystallization due to the distance from a high-temperature region, have better stability and do not need frequent replacement, the tubular body of the heating section is the middle part of the furnace core tube, and the tubular body can be replaced by a material which is resistant to high temperature and corrosion and is not easy to introduce impurities.
The sealing connection for connecting the tube bodies of the furnace core tubes may be any suitable prior art, for example, a sleeve may be provided, the connecting ends of the two tube bodies to be connected are inserted into the sleeve from both ends of the sleeve respectively, and the fitting gap between the connecting ends and the inner wall of the sleeve is small enough to achieve both fixed connection and sealing, wherein one convenient way is a sealing flange for sealing connection.
The furnace core pipe ventilation pipes 7 and 22 arranged on the upper pipe body and the lower pipe body are used for air inlet and outlet of the furnace core pipe, so that dehydrating agent gas can be introduced when needed through protective gas, the furnace core pipe ventilation pipe on the upper pipe body can be provided with a vacuum pump 8 so as to vacuumize the inner cavity of the furnace core pipe, and the furnace core pipe ventilation pipe on the lower pipe body can be provided with a pressure detector 21 for detecting the gas pressure (air inlet side pressure) in the furnace core pipe.
A frame (not drawing) for installing guide rod 1 extends to the top of stove core pipe, install the guide rod in the frame that is located stove core pipe top, and make the guide rod can reciprocate and rotate around its self axis for the frame, can set up the sleeve pipe of injecing the guide rod activity space or the limit structure of similar through-hole form, only allow the guide rod to reciprocate and rotate, install the drive arrangement 2 of guide rod in the frame, be used for driving the guide rod to reciprocate and rotate, during operation with prefabricated stick (or prefabricated stick loose body) 9 fixed mounting at the lower extreme of guide rod, make it along with guide rod synchronous motion.
The guide rod driving device can adopt any appropriate prior art, for example, a feeding and rotating device similar to a drilling machine and other machine tools can be adopted, a rotating driving motor capable of driving the guide rod to rotate and a moving driving motor capable of driving the guide rod to move up and down can be respectively arranged, a uniform driving motor can be arranged to simultaneously drive the guide rod to rotate and move up and down through a corresponding transmission mechanism, and the motor preferably adopts a servo motor.
The upper end of the furnace core pipe is provided with a detachable sealing end cover 6 and a detachable or openable sealing cover 5 positioned on the sealing end cover, the sealing end cover forms the bottom surface of the sealing cover after being installed, a sealing cover cavity is enclosed, the sealing end cover and the sealing cover can adopt proper prior art, for example, the sealing end cover can adopt an inward-raised inner flange structure or a ring shape which is sheltered on the upper end port of the furnace core pipe and can be two symmetrical semi-ring shapes, a central hole of the inner flange structure forms a guide rod hole of a sealing flange, the sealing cover covers the sealing end cover and forms a cylindrical box body with a guide rod hole at the central part of the upper surface and the lower surface together with the sealing end cover, the sealing end cover seals the upper end port of the furnace core pipe in an equal mode that the bottom surface is tightly attached to the upper end surface of the furnace core pipe to form sealing with the upper end surface of the furnace core pipe, and a certain fit clearance is needed between the guide rod, in order to allow the guide rod to reciprocate and rotate, through setting up the sealed cowling and set up sealed cowling ventilation pipe 3 on the sealed cowling, can take out the negative pressure in to the sealed cowling through this ventilation pipe, form certain pressure differential in the upper and lower both sides of end cover, can avoid outside gas to get into in the stove core pipe from the fit clearance between guide rod hole and the guide rod from this, can set up vacuum pump 4 on the sealed cowling ventilation pipe for the interior air exhaust of sealed cowling.
Before the sintering begins, heat the temperature in the heating section body 18 of stove core pipe to dehydration temperature earlier, start the sintering after keeping warm pressurize a period of time, fix prefabricated excellent loose body 9 on guide bar 1, the servo motor through drive arrangement 2 drives the guide bar and drives the loose body and slowly enter into the cavity 11 of upper tube body, wait that the loose body stops descending after completely getting into sintering furnace cavity 11, the upper end port that covers the stove core pipe with end cover 6 realizes sealedly, close sealed cowling 5 after sealed, vacuum pump 4 through sealed cowling bleeds, get rid of the waste gas that sealed department oozed.
The use method of the sintering furnace or the preform sintering method adopting the sintering furnace comprises the following main steps and cautions:
1) determining the temperature field distribution near the furnace core pipe of the high-temperature region by primary use:
when the furnace core pipe is subjected to first temperature rise, after the temperature is raised to the set vitrification sintering temperature of 1450-.
2) Installation of loose optical fiber preform:
and (3) opening the sealing cover, taking out the sealing end cover, installing the loose body of the optical fiber preform on the guide rod, lowering the loose body to the initial position determined in the step 1 at the speed of 5-10 mm/s by controlling a servo motor of the guide rod driving device through a program, buckling the sealing end cover, covering a top cover of the sealing cover, and starting a corresponding vacuum pump to exhaust air so that the interior of the sealing cover is in a negative pressure state.
3) Dehydration sintering
And introducing nitrogen with the flow of 4-8 SLM into the cavity through a ventilation pipe of the sealed cavity to ensure that the sealed cavity is in a high-pressure state, thereby realizing inflation sealing, wherein the air pressure in the cavity can be slightly higher than the external atmospheric pressure, and oxygen in the atmosphere can not enter the sintering furnace. The method comprises the following steps of slowly introducing inert gas helium with the flow rate of 3-5 SLM and dehydrating agent chlorine with the flow rate of 1-2SLM into a furnace core pipe from the bottom through a ventilation pipe of a lower pipe body, simultaneously extracting dehydrating waste gas from the ventilation pipe of an upper pipe body, reducing loose objects at the speed of 3-8mm/min through a servo motor while introducing gas into the furnace core pipe, rotating at the speed of 3-6rpm, and introducing the loose objects into a high-temperature sintering area in a heating section pipe body for dehydrating treatment, wherein the reaction involved in the dehydrating process is as follows:
Cl2+2OH-=2HCl+O2
4) vitrification sintering:
after the loose body completely passes through the high-temperature sintering area, closing the chlorine gas inlet, lifting the dehydrated loose body to the initial position at the speed of 5-10mm/min, and heating the temperature of the high-temperature area to 1450-1500 ℃ at the speed of 5-10 ℃/min by using a heating element. And after the temperature rise is finished, feeding the dehydrated loose body into a high-temperature sintering area again at a descending speed of 5-10mm/min and a rotating speed of 3-6rpm, wherein in the high-temperature sintering area, air holes in the loose body are slowly closed to densify, a transparent glass rod is formed after densification, and in the process of densifying the air holes in the loose body, gas in the air holes flows out from the upper part of the loose body, which is a process of vitrifying the loose body. After the loose bodies completely pass through the high-temperature sintering area, the vitrification process is completed, the vitrified optical fiber preform is lifted to the initial position at the lifting speed of 5-10mm/min and the rotating speed of 3-6rpm, the optical fiber preform passes through the high-temperature sintering area again in the lifting process, the stress in the vitrified optical fiber preform is further reduced, the density distribution of the preform is more uniform, after the preform is lifted to the initial position, the sintering process of the loose bodies is completely completed, after the preform is taken, the sintering furnace is cooled to the dehydration temperature for heat preservation, and the next sintering is performed.
5) Attenuation verification
The initial several times sintered optical fiber preform requires verification of attenuation at 1383nm after drawing to adjust the dehydrated chlorine gas at a more appropriate value, and after normal production, attention is paid to attenuation at 1310nm, 1383nm and 1550nm in order to adjust process parameters as necessary.
6) After cooling, the temperature is raised again
When the number of times of using the furnace core tube reaches a certain value, the temperature of the furnace core tube is reduced to normal temperature, safety inspection is carried out on the heating element, the furnace body and the furnace core tube, as the tube body of the heating section is made of high-temperature resistant materials such as a graphite tube coated with an anti-oxidation film, after the inspection, if the tube body is confirmed to be unnecessary to be replaced, the temperature rise operation is directly carried out, the temperature of the furnace core tube is raised to a set dehydration temperature at the speed of 3-5 ℃/min, heat preservation treatment is carried out, the steps 1-5 are repeated when the tube body is used again after the heat preservation treatment, the attenuation condition of sintering a core rod of the furnace core tube after the temperature rise again is tracked, after the temperature rise is carried out again, the attenuation conditions of the optical fiber at the wavelengths of 1310nm, 1383nm and 1550nm are required to be observed.
Fig. 3 to 5 show the attenuation coefficient at a wavelength of 1310nm, the attenuation coefficient at a wavelength of 1383nm and the attenuation coefficient at a wavelength of 1550nm of a g.652d conventional single mode optical fiber prepared in a conventional manner using the optical fiber preform prepared according to the present invention, respectively, wherein it can be seen that the optical fiber drawn from the sintered optical fiber preform according to the present invention has good attenuation properties at the primary and secondary temperature increases of the furnace core tube.
Because the sintering process is to sinter the deposited preform loose body to be called a vitrified preform, from a macroscopic view, the preform loose body before sintering and the preform after sintering are the same object and the microstructure change of the preform is gradual, the preform and the preform loose body in the specification and other similar terms (corresponding short term and full term) refer to the macroscopic object.
The technical means disclosed by the invention can be combined arbitrarily to form a plurality of different technical schemes except for special description and the further limitation that one technical means is another technical means.
Claims (10)
1. A sectional type optical fiber perform sintering furnace device comprises a furnace core pipe and a guide rod capable of moving up and down, and is characterized in that the furnace core pipe mainly comprises an upper pipe body, a heating section pipe body and a lower pipe body, wherein the upper pipe body and the lower pipe body are quartz glass pipes, the heating section pipe body is a high-temperature resistant pipe body made of high-temperature resistant materials, so that the heating section pipe body does not have folds and cracks of the quartz glass pipes caused by devitrification and uneven stress, the upper pipe body and the lower pipe body are fixedly arranged on the upper end surface and the lower end surface of the heating section pipe body in a detachable connection mode respectively and are connected with the heating section pipe body to form a complete furnace core pipe, a sealing cavity surrounding the pipe body is arranged on the outer side of the heating section pipe body, heating elements are arranged in the sealing cavity, the number of the heating elements is one or more, and the furnace core elements are annularly surrounded on the, the utility model discloses a furnace core pipe, including furnace core pipe, guide rod, sealing end cover, upper tube body, lower tube body, heating section, the installation frame of guide rod is located furnace core pipe's top, the guide rod is equipped with and drives its guide rod drive arrangement who reciprocates and rotate around the axis, furnace core pipe's upper end is equipped with and is used for the sealed end cover of port, sealing end cover adopts the releasable connection mode to fix on furnace core pipe's the upper end port, sealing end cover adopts the components of a whole that can function independently structure, divide into two parts that can involution each other at least and leave the confession in involution department the guide rod hole that the guide rod passed, go up the body and lower tube body with the releasable connection mode between the heating:
1) connecting with a flange;
2) the connecting end surfaces of the two connected pipe bodies are provided with tongue-and-groove structures which can be mutually involutory and are involutory together through the corresponding tongue-and-groove structures;
3) the plane end faces of the two connected pipe bodies are mutually involuted;
4) the connecting ends of two connected pipe bodies are inserted into the same connecting sleeve, the two pipe bodies are directly fixed or respectively fixed on respective or common machine frames, and a seal is arranged between the mutually connected pipe bodies.
2. The apparatus of claim 1, wherein the upper and lower tubular bodies are removably connected to the heating section tubular body by a sealing connection.
3. The apparatus according to claim 1 or 2, wherein the upper and lower tubular bodies are provided with respective muffle tube ventilation tubes.
4. The apparatus according to claim 1 or 2, wherein the upper end of the muffle is provided with a sealing cap above the sealing end cap, the sealing cap being detachably mounted on the upper end of the muffle and/or the top cap of the sealing cap being an openable top cap.
5. The apparatus of claim 4 wherein said end face seal housing is provided with a seal housing vent tube.
6. The apparatus according to claim 1 or 2, wherein the heating section tube body is provided at an outer side thereof with an annularly surrounding sealed chamber housing, a sealed space between the sealed chamber housing and the heating section tube body constitutes the sealed chamber, the sealed chamber housing is preferably a cylindrical housing, and a central portion of upper and lower end surfaces thereof is provided with a furnace core tube hole for passing a furnace core tube therethrough.
7. The apparatus of claim 6 wherein said sealed chamber housing is provided with a sealed chamber vent tube.
8. A method for sintering an optical fiber preform, characterized in that the segmented optical fiber preform sintering furnace device of any one of claims 1 to 7 is used to sinter the optical fiber preform, loose bodies of the optical fiber preform to be sintered are fixedly arranged at the lower end of the leading bar, the leading bar is driven by the leading bar driving device to move downwards, the loose bodies of the preform are moved to an initial position set in the upper pipe body, a heating element forms a required high temperature in a high-temperature sintering area in the heating section pipe body according to process requirements, the leading bar drives the loose bodies of the preform to enter and/or pass through the high-temperature sintering area in the heating section pipe body for high-temperature treatment under the driving of the leading bar driving device, and then returns to the initial position in the upper pipe body again, the high-temperature treatment is carried out once or more times, so that the loose bodies of the preform can realize required vitrification, and forming an optical fiber preform, wherein in the process of moving the preform into the furnace core tube from the upper part of the furnace core tube and in the process of moving the preform into the upper part of the furnace core tube from the inside of the furnace core tube, the top of the furnace core tube is not provided with a sealing end cover and a sealing cover, namely the sealing end cover and the sealing cover are detached from the furnace core tube, and after the preform enters the furnace core tube, the sealing end cover and the sealing cover are arranged on the furnace core tube to seal the upper port of the furnace core tube.
9. The method for sintering an optical fiber preform according to claim 8, wherein the high temperature treatment is performed twice, the first high temperature treatment is a dehydration treatment, the inert shielding gas and chlorine gas used as a dehydrating agent are continuously introduced into the core tube through the core tube ventilation tube provided in the lower tube body, the pressure in the core tube is in a positive pressure state, the exhaust gas is discharged through the core tube ventilation tube provided in the upper tube body, the temperature in the high temperature sintering region is brought to a dehydration treatment temperature by the heating element, the lead rod is moved down at a constant speed and rotated at a constant speed by the lead rod driving device, the chlorine gas is turned off after the preform bulk passes through the high temperature sintering region of the tube body in the heating section, the dehydrated preform bulk is lifted to an initial position, the second high temperature treatment is a glass transition sintering treatment, the second high temperature treatment is performed after the first high temperature treatment, the high temperature sintering region is at a glass transition temperature when passing through, the guide rod moves downwards at a constant speed and rotates at a constant speed under the drive of the guide rod driving device, and after the loose body of the prefabricated rod passes through the high-temperature sintering area of the tube body at the heating section, the guide rod moves upwards at a constant speed and rotates at a constant speed under the drive of the guide rod driving device until the vitrified prefabricated rod returns to the initial position.
10. The method of claim 9, wherein the dehydration temperature and the glass transition sintering temperature are 1050-1100 ℃ and 1450-1500 ℃, respectively, the downward movement speed of the rod during the dehydration is 3-8mm/min, the rotational speed during the downward movement is 3-6rpm, and the upward movement speed is 5-10mm/min, the downward movement speed of the rod during the glass transition sintering process is 5-10mm/min, the rotational speed during the downward movement is 3-6rpm, the upward movement speed is 5-10mm/min, and the rotational speed during the upward movement is 3-6rpm, and during all the high temperature processing, the sealing cover is evacuated to a negative pressure, and the sealing cavity is protected by inert gas and is in a positive pressure state.
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| CN108218217A (en) * | 2018-04-11 | 2018-06-29 | 王丽 | A kind of preform for fiber manufacturing manufactures device |
| CN109502962A (en) * | 2018-12-28 | 2019-03-22 | 通鼎互联信息股份有限公司 | A kind of sintering equipment and sintering method of preform |
| CN110550857B (en) * | 2019-08-19 | 2022-06-24 | 湖州维德光电科技有限公司 | Optical fiber perform gaseous economizer |
| CN110776251A (en) * | 2019-12-05 | 2020-02-11 | 江苏亨通光导新材料有限公司 | Furnace core pipe for sintering optical fiber preform rod and replacement method thereof |
| CN110818238A (en) * | 2019-12-11 | 2020-02-21 | 江苏通鼎光棒有限公司 | Annealing device and method for improving stress of preform |
| CN111320375A (en) * | 2020-04-13 | 2020-06-23 | 远东通讯有限公司 | VAD loose body dehydration sintering device |
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| CN112624600B (en) * | 2021-01-12 | 2023-06-23 | 江苏法尔胜光子有限公司 | Sintering furnace exhaust hood for preparing optical fiber preform and on-line adjusting method of exhaust pressure |
| CN112645583A (en) * | 2021-01-13 | 2021-04-13 | 烽火通信科技股份有限公司 | System and method for automatically controlling pressure in optical fiber preform sintering furnace |
| CN113277728B (en) * | 2021-07-01 | 2023-06-09 | 中国计量大学 | Optical fiber drawing furnace suitable for fluoride glass |
| CN114398529B (en) * | 2021-12-27 | 2023-12-01 | 江苏亨通数字智能科技有限公司 | Optical wand disassembly method, optical wand disassembly device and storage medium |
| CN115974399A (en) * | 2022-12-26 | 2023-04-18 | 藤仓烽火光电材料科技有限公司 | Dehydration system and dehydration method for loose body |
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