CN114524609B - Preparation device and preparation method of optical fiber preform - Google Patents
Preparation device and preparation method of optical fiber preform Download PDFInfo
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- CN114524609B CN114524609B CN202210326664.1A CN202210326664A CN114524609B CN 114524609 B CN114524609 B CN 114524609B CN 202210326664 A CN202210326664 A CN 202210326664A CN 114524609 B CN114524609 B CN 114524609B
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 55
- 238000002360 preparation method Methods 0.000 title claims abstract description 36
- 239000000835 fiber Substances 0.000 claims abstract description 72
- 239000000156 glass melt Substances 0.000 claims abstract description 43
- 238000001125 extrusion Methods 0.000 claims abstract description 38
- 230000007246 mechanism Effects 0.000 claims abstract description 25
- 238000003825 pressing Methods 0.000 claims abstract description 13
- 239000011521 glass Substances 0.000 claims description 103
- 238000005253 cladding Methods 0.000 claims description 79
- 230000006835 compression Effects 0.000 claims description 25
- 238000007906 compression Methods 0.000 claims description 25
- 238000002844 melting Methods 0.000 claims description 21
- 230000008018 melting Effects 0.000 claims description 21
- 238000001816 cooling Methods 0.000 claims description 19
- 239000000758 substrate Substances 0.000 claims description 12
- 238000005266 casting Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 230000009969 flowable effect Effects 0.000 claims description 10
- 238000004321 preservation Methods 0.000 claims description 10
- 230000002093 peripheral effect Effects 0.000 claims description 8
- 238000000137 annealing Methods 0.000 claims description 5
- 238000007789 sealing Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 30
- 230000008569 process Effects 0.000 description 10
- 239000000203 mixture Substances 0.000 description 8
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 4
- 235000017491 Bambusa tulda Nutrition 0.000 description 4
- 241001330002 Bambuseae Species 0.000 description 4
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 4
- 239000011425 bamboo Substances 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000002419 bulk glass Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/01265—Manufacture of preforms for drawing fibres or filaments starting entirely or partially from molten glass, e.g. by dipping a preform in a melt
- C03B37/01274—Manufacture of preforms for drawing fibres or filaments starting entirely or partially from molten glass, e.g. by dipping a preform in a melt by extrusion or drawing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
The invention discloses a preparation device of an optical fiber preform and a preparation method thereof, wherein the preparation device comprises an extrusion die, a lifting table and a supporting mechanism, the extrusion die comprises a pressing rod, a top die, a barrel die and a bottom die which are sequentially and detachably connected from top to bottom, the top die is of a groove-shaped structure with an upward opening, the pressing rod is arranged in the groove-shaped structure in a sliding manner along the vertical direction, the structure of the pressing rod is matched with an inner cavity of the groove-shaped structure, a through hole is formed in the bottom of the groove-shaped structure, the barrel die is of a cylindrical structure, the axis of the barrel die is opposite to the through hole, the pressing rod is used for stably extruding fiber core glass melt in the groove-shaped structure, the fiber core glass melt which is not solidified at the axis of the barrel die enters the axis of the barrel die, and the unconsolidated clad glass melt at the axis of the barrel die is ejected out, so that the optical fiber preform with good fiber core diameter uniformity, wide fiber core/clad ratio adjustable range and small interface loss is obtained.
Description
Technical Field
The invention relates to the field of optical fiber preform manufacturing, in particular to a preparation device and a preparation method of an optical fiber preform.
Background
Since the success of improved vapor deposition in 1970, quartz fibers having transmission losses of only 20dB/km have been developed by Corning, USA, the fiber has received extensive attention and has been rapidly developed. The core of the optical fiber manufacturing process is the preparation technology of the optical fiber preform. The common preparation methods of the optical fiber preform at present mainly comprise a chemical vapor deposition method, a tube rod method, an extrusion method, a rotary casting method, a suction injection method and the like. In general, a multi-component glass optical fiber preform may be prepared by a tube-rod method, an extrusion method, or the like, in addition to the chemical vapor deposition method being applicable only to quartz optical fibers. It is well known that the loss of an optical fiber is mainly three-dimensional, including the intrinsic loss of the glass matrix, the end-face coupling loss, and the interface loss between the cladding and the core, which is usually dominant. How to reduce or even eliminate the interface loss is critical to reducing the fiber loss.
The tube rod method is to prepare block glass, then prepare cladding sleeve and core rod through cold working means such as cutting, grinding, polishing and the like, and then insert the core rod into the cladding sleeve to obtain the optical fiber preform. The method has high requirements on the optical quality of the bulk glass and the precision of mechanical processing equipment, and a gap is inevitably formed between the cladding sleeve and the fiber core rod, so that the interface defects of the optical fiber prepared by the tube rod method are more.
The extrusion method is operated under the state that the glass is in high viscosity, the processing temperature is generally set near the softening point temperature of the glass, the interface bonding degree of the obtained optical fiber preform is good, but extrusion equipment is complex and the precision requirement is high.
The rotary casting method is to cast the cladding glass melt into a preheated mold to form a cladding sleeve with uniform inner diameter through centrifugal force of high-speed rotation, and then pour the fiber core glass melt into the cladding sleeve to form the preform. The fiber core diameter of the optical fiber preform prepared by the rotary casting method is generally larger, and the adjustable range of the fiber core/cladding ratio is small.
The sucking and injecting method is to suck the fiber core glass melt at the top of the mold into the cladding glass to obtain the optical fiber preform by taking the volume shrinkage of the cladding glass melt in the liquid storage tank at the bottom of the mold as driving force in the cooling process. The suction injection method can be used for preparing the optical fiber preform with excellent interface bonding degree, the preparation device is simple, the operation is convenient, but the uniformity of the fiber core diameter is poor, and the fiber core rod presents an elongated V-shaped structure. This is because the glass has a low coefficient of thermal conductivity, and during natural cooling, the glass melt near the metal mold solidifies first and gradually slowly develops toward the core, but the time span of the volume shrinkage process is longer, and during the gradual drawing into the core glass melt, the non-solidifying range at the core of the cladding glass corresponding thereto is gradually reduced, and because the core glass melt temperature is relatively high, heat transfer occurs after contacting the solidified cladding glass, causing remelting thereof, and in addition, the rate of volume shrinkage is gradually reduced as the glass melt gradually solidifies from the outer periphery to the inner periphery, thereby causing non-uniformity in the diameter of the core.
Disclosure of Invention
The invention aims to provide a preparation device and a preparation method of an optical fiber preform, which solve the problems of the prior art, have the advantages of low production cost, short period, simple preparation device, simple and convenient operation and the like, and more importantly, can obtain the optical fiber preform with good uniformity of fiber core diameter, wide adjustable range of fiber core/cladding ratio and small interface loss.
In order to achieve the above object, the present invention provides the following solutions: the invention provides a preparation device of an optical fiber preform, which comprises an extrusion die, a lifting table and a supporting mechanism; the extrusion die comprises a compression bar, a top die, a barrel die and a bottom die which are sequentially and detachably connected from top to bottom, wherein the top die is of a groove-shaped structure with an upward opening, the compression bar is arranged in the groove-shaped structure in a sliding manner along the vertical direction, the structure of the compression bar is matched with an inner cavity of the groove-shaped structure, a through hole is formed in the bottom of the groove-shaped structure, the barrel die is of a cylindrical structure, the axis of the barrel die is opposite to the through hole, the barrel die is vertically fixed on the supporting mechanism, a first annular flange is arranged on the inner peripheral wall of the bottom end of the barrel die, and the lifting table is movably arranged below the bottom die along the vertical direction and supports the bottom die to be abutted and blocked at the bottom end of the barrel die.
Preferably, the bottom of the inner cavity of the groove-shaped structure is in a tapered structure which is gradually reduced downwards, and the through hole is positioned at the vertex of the tapered structure.
Preferably, the structure of the through holes is matched to the desired preformed core structure.
Preferably, a boss and a groove which are embedded are arranged between the bottom end of the top die and the top end of the barrel die.
Preferably, the supporting mechanism is provided with a supporting interval, and the peripheral wall at the top end of the barrel mold is provided with a second annular flange which is used for being clamped on the supporting interval.
Preferably, the top end of the bottom die is provided with a groove matched with the bottom end of the barrel die and used for limiting, the bottom die is provided with an inner cavity communicated with the barrel die, and the inner cavity is of a stepped structure with a narrow upper part and a wide lower part.
Preferably, the structure of the top of the step-like structure is larger than the inner ring structure of the first annular flange.
Preferably, the bottom of the step-shaped structure penetrates through the bottom wall of the bottom die, and a substrate for blocking the bottom of the step-shaped structure is arranged on the lifting table.
Also provided is a method for preparing an optical fiber preform, comprising the steps of:
Preparation: placing the cylindrical die, the bottom die and the base plate into an electric furnace at 200-350 ℃ for heat preservation for 2 hours, and placing the top die and the pressing rod into the electric furnace at 400-600 ℃ for heat preservation for 2 hours;
melting: simultaneously melting cladding glass and fiber core glass in a melting furnace;
And (3) installing a die: taking the cylindrical die, the bottom die and the substrate out of the electric furnace, and adjusting the lifting table to fix the cylindrical die, the bottom die and the substrate on the supporting mechanism;
Casting a clad glass melt: taking out the cladding glass melt from the melting furnace, placing for 20-40s, pouring the cladding glass melt into a barrel mold, and naturally cooling for 100-600s to enable the cladding glass to be in a state that the periphery is solidified and the axis is flowable;
casting a core glass melt: taking out the fiber core glass melt from the melting furnace, placing for 20-40s, taking out the top die from the electric furnace and fixing the top die on the barrel die, pouring the fiber core glass melt into the top die, taking out the pressing rod from the electric furnace and placing the pressing rod on the surface of the fiber core glass melt, adjusting the lifting table, and removing the bottom die;
Extruding: transferring the extrusion die and the supporting mechanism to an automatic hydraulic press, starting the hydraulic press, extruding fiber core glass melt into peripherally solidified cladding glass through a compression bar at the extrusion speed of 0.5-5mm/s, ejecting the cladding glass melt with a flowable axle center, closing the hydraulic press, transferring the extrusion die into an electric furnace, annealing for 3 hours, and cooling to room temperature along with the furnace;
taking out the finished product: and disassembling the die and taking out the optical fiber preform.
Preferably, after the counter die is removed, the solidified clad glass in the counter die can be recovered.
Compared with the prior art, the invention has the following technical effects:
First, the extrusion die comprises a compression bar, a top die, a barrel die and a bottom die which are sequentially and detachably connected from top to bottom, the top die is of a groove-shaped structure with an upward opening, the compression bar is arranged in the groove-shaped structure in a sliding way along the vertical direction, the structure of the compression bar is matched with the inner cavity of the groove-shaped structure, a through hole is formed in the bottom of the groove-shaped structure, the barrel die is of a cylindrical structure, the axis of the barrel die is opposite to the through hole, the barrel die is vertically fixed on a supporting mechanism, a first annular flange is arranged on the inner peripheral wall of the bottom end of the barrel die, a lifting table is movably arranged below the bottom die along the vertical direction and supports the bottom die to be abutted and blocked at the bottom end of the barrel die, after the casting of cladding glass melt is completed, the outer peripheral side of cladding glass can be solidified firstly and gradually developed to the axis in the natural cooling process, the solidified cladding glass is supported through the first annular flange, then the bottom die is dismantled, the non-solidified part at the axis of the cladding glass is in a through structure at two ends, the fiber core glass melt in the groove-shaped structure is stably extruded through the pressing rod, the fiber core glass melt enters the axis of the barrel die through the bottom through hole of the groove-shaped structure, the non-solidified cladding glass melt at the axis is ejected out, and the optical fiber preform with good fiber core diameter uniformity, wide fiber core/cladding ratio adjustable range and small interface loss is obtained; and high-quality bulk glass does not need to be prepared in advance, and continuous operation of glass melting and preform molding can be realized, so that the preparation period is greatly shortened, and the production cost is low.
Secondly, the bottom of the inner cavity of the groove-shaped structure is of a conical structure which is gradually reduced downwards, the through hole is arranged at the top of the conical structure, the fiber core glass melt in the groove-shaped structure can be gradually converged at the top of the conical structure by arranging the conical structure, so that the pressure of the fiber core glass melt by the pressing rod is buffered, the fiber core glass melt is prevented from overflowing in the moving process of the pressing rod, the fiber core glass melt is converged at the through hole of the conical structure, the concentrated pressure on the cladding glass melt is easier to be formed, the cladding glass melt can be rapidly ejected out, the time span of the whole extrusion process is very short, the range of the uncured part in the cladding glass is hardly changed during the time, and therefore, the uniformity of the fiber core diameter of the optical fiber preform obtained by the suction injection method in the prior art is mainly due to the fact that the time span of volume shrinkage is long, the uncured part is obviously different up and down, and enough time is used for carrying out heat transfer, so that the extruding time of the upper wide and lower narrow V-shaped structure is very short, and the range of the extrusion time is very little, and the heat transfer is very little, and the uniformity of the obtained fiber core is very good.
Thirdly, the structure of the through hole is matched with the fiber core structure required to be prefabricated, and then the fiber core glass melt extruded by the through hole can directly and stably eject the non-solidified part in the cladding glass, so that the unstable flow possibly caused by the structural change of the runner is avoided, the defects of bubble stripes and the like are introduced, or the adverse effects of irregular fiber core structure and the like caused by incomplete ejection are avoided, and the preparation efficiency of the optical fiber preform is improved.
Fourth, have looks gomphosis's boss and recess between top mould bottom and the section of thick bamboo mould top, and then through boss and recess's joint for stable connection between top mould and the section of thick bamboo mould, avoid the depression bar in extrusion process, the separation of top mould and section of thick bamboo mould that causes easily, thereby lead to spilling over of fine core glass fuse-element.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the overall structure of the present invention;
FIG. 2 is a diagram of the steps of the preparation process of the present invention;
Wherein, 1-depression bar, 2-top mould, 3-section of thick bamboo mould, 4-supporting mechanism, 5-die block, 6-base plate, 7-elevating platform, 8-cladding glass, 9-fiber core glass.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a preparation device and a preparation method of an optical fiber preform, which solve the problems of the prior art, have the advantages of low production cost, short period, simple preparation device, simple and convenient operation and the like, and more importantly, can obtain the optical fiber preform with good uniformity of fiber core diameter, wide adjustable range of fiber core/cladding ratio and small interface loss.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Referring to fig. 1 to 2, the present embodiment provides an apparatus for preparing an optical fiber preform, which includes an extrusion die, a lifting table 7 and a supporting mechanism 4; the extrusion die comprises a compression bar 1, a top die 2, a barrel die 3 and a bottom die 5 which are sequentially and detachably connected from top to bottom, the top die 2 is of a groove-shaped structure with an upward opening, the compression bar 1 is arranged in the groove-shaped structure in a sliding manner along the vertical direction, the structure of the compression bar 1 is matched with the inner cavity of the groove-shaped structure, a through hole is formed in the groove bottom of the groove-shaped structure, the barrel die 3 is of a cylindrical structure, the inner diameter of the barrel die 3 determines the size of an optical fiber preform, the axis of the barrel die 3 is opposite to the through hole, the barrel die 3 is vertically fixed on a supporting mechanism 4, a first annular flange is arranged on the inner periphery of the bottom end of the barrel die 3, the inner diameter of the bottom of the barrel die 3 is slightly smaller than the inner diameter of the main body of the barrel die 3, a lifting table 7 is movably arranged below the bottom die 5 along the vertical direction and supports the bottom die 5 to be abutted and blocked at the bottom end of the barrel die 3, and after casting of a cladding glass 8 melt is finished, the outer peripheral side of the cladding glass 8 is firstly solidified and gradually developed towards the axis in the natural cooling process, the solidified cladding glass 8 is supported by the first annular flange, then the bottom die 5 is removed, the non-solidified part at the axis of the cladding glass 8 is in a two-end through structure, the fiber core glass 9 melt in the groove-shaped structure is stably extruded by the compression bar 1, the fiber core glass 9 melt enters the axis of the barrel die 3 through the bottom through hole of the groove-shaped structure, the non-solidified cladding glass 8 melt at the axis is ejected out, and the optical fiber preform with good fiber core diameter uniformity, wide fiber core/cladding ratio adjustable range and small interface loss is obtained; and high-quality bulk glass does not need to be prepared in advance, and continuous operation of glass melting and preform molding can be realized, so that the preparation period is greatly shortened, and the production cost is low.
It should be noted that the glass has a low coefficient of thermal conductivity, and the outer periphery of the melt of the clad glass 8 in the barrel mold 3 solidifies and gradually develops to the axial center during natural cooling. When the cooling time is shorter and the diameter of the non-solidified part of the axis is larger, after the bottom die 5 is removed, the gravity borne by the glass melt is larger than the viscous resistance, the cladding glass 8 melt flows out together with the fiber core glass 9 melt, and the driving force, namely the resultant force of the gravity and the viscous resistance, is gradually reduced and the time span is slightly longer, so that the uniformity of the fiber core diameter of the obtained optical fiber preform is not ideal. And cooling is continued for a period of time, when the diameter of the part of the axis which is not solidified is reduced to a certain critical value, the gravity born by the glass melt is equivalent to viscous resistance, the glass melt cannot flow out after the bottom die 5 is removed, and the fiber core glass 9 melt can be extruded into the cladding glass with solidified periphery by using stable pressure to prepare the optical fiber preform. Therefore, the preparation device and the preparation method of the optical fiber perform are suitable for preparing the optical fiber perform with the fiber core diameter of about 2-3mm, and the optical fiber perform with different fiber core/cladding ratios can be obtained by adjusting the inner diameter of the barrel mold 3.
Further, the inner chamber bottom of slot form structure is the toper structure that dwindles gradually downwards, the through-hole is located the summit of toper structure, through setting up the toper structure, the fine core glass 9 melt in the slot form structure can assemble the summit department of toper structure gradually, with the pressure of buffering depression bar 1 to fine core glass 9 melt, avoid fine core glass 9 melt to appear excessive in the removal in-process of depression bar 1, and fine core glass 9 melt gathers in the through-hole department of toper structure, form concentrated pressure to the cladding glass 8 melt more easily, can be ejecting the cladding glass 8 melt fast, the time span of whole extrusion process is very short, the scope of unset part hardly changes in the cladding glass 8 during this period, thereby the homogeneity of fine core diameter has been ensured.
The structure of the through hole is matched with the required prefabricated fiber core structure, and the fiber core glass 9 melt extruded by the through hole can directly and stably eject the non-solidified part in the cladding glass 8, so that unstable flow possibly caused by the change of the flow channel structure is avoided, defects such as bubble stripes are introduced, the fiber core structure is irregular and the like caused by incomplete ejection are avoided, and the preparation efficiency of the optical fiber preform is improved.
Preferably, a boss and a groove which are mutually embedded are arranged between the bottom end of the top die 2 and the top end of the barrel die 3, and then the top die 2 can be stably connected with the barrel die 3 through the clamping connection of the boss and the groove, so that the separation of the top die 2 and the barrel die 3, which is easily caused in the extrusion process, of the compression bar 1 is avoided, and the overflow of the fiber core glass 9 melt is caused.
As a preferred embodiment of the present invention, the supporting mechanism 4 is provided with a supporting space, and the outer peripheral wall of the top end of the barrel mold 3 is provided with a second annular flange for being clamped on the supporting space, so that the barrel mold 3 can be stably fixed on the supporting mechanism 4, for example, the supporting mechanism 4 adopts a frame structure, the top end of the supporting mechanism is provided with a fixing plate, and the fixing plate is provided with an opening for fixing the second annular flange.
The top of the bottom die 5 is provided with a groove matched with the bottom end of the cylindrical die 3 and used for limiting, the bottom die 5 and the cylindrical die 3 are conveniently connected and kept coaxial, the bottom die 5 is provided with an inner cavity communicated with the cylindrical die 3, the inner cavity is of a stepped structure with a narrow upper part and a wide lower part, when the lifting table 7 descends to enable the bottom die 5 to be suspended, the cladding glass 8 is gradually solidified in the inner cavity to form a stepped structure with a narrow upper part and a wide lower part, the bottom die 5 can be clamped by the stepped structure and is fixed at the bottom end of the cylindrical die 3, the inner cavity of the bottom die 5 is prevented from being of a straight cylindrical structure, the bottom die 5 directly slides down after the lifting table 7 descends, and then the cladding glass 8 formed at the bottom die 5 still needs to be knocked down by means of another tool.
As the preferred embodiment of the invention, the structure of the top of the step-shaped structure is larger than the inner ring structure of the first annular flange, so that the structure of the cladding glass 8 formed at the top of the step-shaped structure is larger than the structure of the cladding glass 8 at the first annular flange, and the corresponding structure of the cladding glass 8 at the bottom die 5 can be easily separated from the structure of the cladding glass 8 at the first flange in the process of removing the bottom die 5, thereby improving the convenience of separating the cladding glass 8.
Further, the bottom of the step-shaped structure penetrates through the bottom wall of the bottom die 5, the lifting table 7 is provided with a base plate 6 for plugging the bottom of the step-shaped structure, so that the cladding glass 8 formed in the bottom die 5 can be conveniently separated from the bottom die 5 after the bottom die 5 is disassembled, and the bottom die 5 can be sealed by the base plate 6, so that the forming of the cladding glass 8 is ensured.
Also provided is a method for preparing an optical fiber preform, comprising the steps of:
Preparation: placing the cylindrical die 3, the bottom die 5 and the substrate 6 into an electric furnace at 200-350 ℃ for heat preservation for 2 hours, and placing the top die 2 and the compression bar 1 into the electric furnace at 400-600 ℃ for heat preservation for 2 hours;
melting: simultaneously melting cladding glass 8 and core glass 9 in a melting furnace;
and (3) installing a die: taking the cylindrical die 3, the bottom die 5 and the substrate 6 out of the electric furnace, and adjusting the lifting table 7 to fix the cylindrical die, the bottom die and the substrate on the supporting mechanism 4;
casting a cladding glass 8 melt: taking out the cladding glass 8 melt from the melting furnace, placing for 20-40s, pouring the cladding glass 8 melt into the barrel mold 3, and naturally cooling for 100-600s, so that the cladding glass 8 melt is in a state that the periphery is solidified and the axis is flowable;
casting a fiber core glass 9 melt: taking out the fiber core glass 9 melt from the melting furnace, placing for 20-40s, taking out the top die 2 from the electric furnace and fixing the top die on the barrel die 3, pouring the fiber core glass 9 melt into the top die 2, taking out the compression bar 1 from the electric furnace and placing on the surface of the fiber core glass 9 melt, adjusting the lifting table 7, and removing the bottom die 5;
Extruding: transferring the extrusion die and the supporting mechanism 4 to an automatic hydraulic press, starting the hydraulic press, extruding the fiber core glass 9 melt into the peripherally solidified cladding glass through the compression bar 1 at the extrusion speed of 0.5-5mm/s, ejecting the melt of the cladding glass 8 with the flowable axle center, closing the hydraulic press, transferring the extrusion die into an electric furnace, annealing for 3 hours, and cooling to room temperature along with the furnace;
taking out the finished product: and disassembling the die and taking out the optical fiber preform.
Further, after the bottom die 5 is removed, the solidified cladding glass 8 in the bottom die 5 can be recovered and used for the next preparation of the optical fiber preform.
Further, examples of preparing optical fiber preforms of different structures are as follows:
Example 1
Placing the barrel mold 3, the bottom mold 5 and the substrate 6 into an electric furnace at 330 ℃ for heat preservation for 2 hours, and placing the top mold 2 and the compression bar 1 into the electric furnace at 600 ℃ for heat preservation for 2 hours; the glass composition of the fiber core of the preform rod is 53ZrF 4-20BaF2-4LaF3-3AlF3 -20NaF, the glass composition of the cladding is 53ZrF 4-15BaF2-4LaF3-3AlF3 -25NaF, and the glass composition is weighed and then put into a platinum crucible respectively to be melted for 1 hour at 900 ℃; taking the cylindrical mold 3, the bottom mold 5 and the substrate 6 out of the electric furnace, and adjusting the lifting table 7 to fix the same on the supporting mechanism 4, as shown in fig. 2 a; taking out the cladding glass 8 melt from the melting furnace, placing for 40s, pouring the cladding glass 8 melt into the barrel mold 3, and naturally cooling for 400s, so that the cladding glass 8 is in a state that the periphery is solidified and the axis is flowable; taking out the fiber core glass 9 melt from the melting furnace, placing for 40s, as shown in the b-c diagram of fig. 2, taking out the top mold 2 from the electric furnace and fixing the top mold on the barrel mold 3, pouring the fiber core glass 9 melt into the top mold 2, taking out the compression bar 1 from the electric furnace and placing on the surface of the fiber core glass 9 melt, adjusting the lifting table 7, and removing the bottom mold 5; transferring the extrusion die and the supporting mechanism 4 to an automatic hydraulic press, starting the hydraulic press, extruding the fiber core glass 9 melt into the peripherally solidified cladding glass 8 through a compression bar 1, ejecting the melt of the cladding glass 8 with a flowable axle center, closing the hydraulic press, transferring the extrusion die into an electric furnace, annealing for 3 hours, and cooling to room temperature along with the furnace; and disassembling the die, taking out the optical fiber preform, and finally obtaining the optical fiber preform with the diameter of 20mm and the diameter of the fiber core of 3mm.
Example 2
The same glass composition, preparation mold and operation procedure as in example 1 were adopted, the top mold 2 having a through-hole structure matched with the preform core structure was used, and the natural cooling time and extrusion speed were changed, and the clad glass 8 melt was poured into the barrel mold 3 and naturally cooled for 430 seconds, and then extrusion was started at an extrusion speed of 2mm/s, to finally obtain an optical fiber preform having a diameter of 20mm and a core diameter of 2.2mm.
Example 3
Placing the cylindrical die 3, the bottom die 5 and the substrate 6 into an electric furnace at 300 ℃ for heat preservation for 2 hours, and placing the top die 2 and the compression bar 1 into the electric furnace at 580 ℃ for heat preservation for 2 hours; the glass composition of the fiber core of the preform rod is 70TeO 2-20BaF2-10Y2O3, the glass composition of the cladding is 33AlF3-9BaF2-17CaF2-12YF3-8SrF2-11MgF2-10TeO2,, the glass composition is put into a platinum crucible respectively, and melted for 1 hour at 850 ℃, the barrel mold 3, the bottom mold 5 and the base plate 6 are taken out from an electric furnace, and the lifting table 7 is adjusted to be fixed on the supporting mechanism 4; taking out the cladding glass 8 melt from the melting furnace, placing for 30s, pouring the cladding glass 8 melt into the barrel mold 3, and naturally cooling for 260s, so that the cladding glass 8 is in a state that the periphery is solidified and the axis is flowable; taking out the fiber core glass 9 melt from the melting furnace, placing for 30s, taking out the top die 2 from the electric furnace and fixing the top die on the barrel die 3, pouring the fiber core glass 9 melt into the top die 2, taking out the compression bar 1 from the electric furnace and placing on the surface of the fiber core glass 9 melt, adjusting the lifting table 7, and removing the bottom die 5; transferring the extrusion die and the supporting mechanism 4 to an automatic hydraulic press, starting the hydraulic press, extruding the fiber core glass 9 melt into the cladding glass 8 with solidified periphery through the compression bar 1 at the extrusion speed of 2mm/s, ejecting the cladding glass 8 melt with flowable axle center, closing the hydraulic press, transferring the extrusion die into an electric furnace, annealing for 3 hours, and cooling to room temperature along with the furnace; and disassembling the die, taking out the optical fiber preform, and finally obtaining the optical fiber preform with the diameter of 15mm and the diameter of the fiber core of 2.8mm.
Example 4
The same glass composition, preparation mold and operation procedure as in example 3 were adopted, the top mold 2 having a through-hole structure matched with the preform core structure was used, and the natural cooling time and extrusion speed were changed, and the clad glass 8 melt was poured into the barrel mold 3 and naturally cooled for 275s, and then extrusion was started at an extrusion speed of 1.5mm/s, to finally obtain an optical fiber preform having a diameter of 15mm and a core having a diameter of 2.4mm.
The adaptation to the actual need is within the scope of the invention.
It should be noted that it will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
The principles and embodiments of the present invention have been described in detail with reference to specific examples, which are provided to facilitate understanding of the method and core ideas of the present invention; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (6)
1. The preparation method of the optical fiber preform is characterized in that the preparation device used by the preparation method comprises an extrusion die, a lifting table and a supporting mechanism; the extrusion die comprises a compression bar, a top die, a barrel die and a bottom die which are sequentially and detachably connected from top to bottom, wherein the top die is of a groove-shaped structure with an upward opening, the compression bar is arranged in the groove-shaped structure in a sliding manner along the vertical direction, the structure of the compression bar is matched with the inner cavity of the groove-shaped structure, a through hole is formed in the bottom of the groove-shaped structure, the barrel die is of a cylindrical structure, the axis of the barrel die is opposite to the through hole, the barrel die is vertically fixed on the supporting mechanism, a first annular flange is arranged on the inner peripheral wall of the bottom end of the barrel die, and the lifting table is movably arranged below the bottom die along the vertical direction and supports the bottom die to be abutted and blocked at the bottom end of the barrel die;
the top end of the bottom die is provided with a groove matched with the bottom end of the barrel die and used for limiting, the bottom die is provided with an inner cavity communicated with the barrel die, and the inner cavity is of a stepped structure with a narrow upper part and a wide lower part;
the bottom of the inner cavity of the groove-shaped structure is of a tapered structure which is gradually reduced downwards, and the through hole is positioned at the vertex of the tapered structure;
the structure of the top of the step-shaped structure is larger than the inner ring structure of the first annular flange;
the preparation method of the optical fiber preform rod comprises the following steps:
Preparation: placing the cylindrical die, the bottom die and the base plate into an electric furnace at 200-350 ℃ for heat preservation for 2 hours, and placing the top die and the pressing rod into the electric furnace at 400-600 ℃ for heat preservation for 2 hours;
melting: simultaneously melting cladding glass and fiber core glass in a melting furnace;
And (3) installing a die: taking the cylindrical die, the bottom die and the substrate out of the electric furnace, and adjusting the lifting table to fix the cylindrical die, the bottom die and the substrate on the supporting mechanism;
Casting a clad glass melt: taking out the cladding glass melt from the melting furnace, placing for 20-40s, pouring the cladding glass melt into a barrel mold, and naturally cooling for 100-600s to enable the cladding glass to be in a state that the periphery is solidified and the axis is flowable;
casting a core glass melt: taking out the fiber core glass melt from the melting furnace, placing for 20-40s, taking out the top die from the electric furnace and fixing the top die on the barrel die, pouring the fiber core glass melt into the top die, taking out the pressing rod from the electric furnace and placing the pressing rod on the surface of the fiber core glass melt, adjusting the lifting table, and removing the bottom die;
Extruding: transferring the extrusion die and the supporting mechanism to an automatic hydraulic press, starting the hydraulic press, extruding fiber core glass melt into peripherally solidified cladding glass through a compression bar at the extrusion speed of 0.5-5mm/s, ejecting the cladding glass melt with a flowable axle center, closing the hydraulic press, transferring the extrusion die into an electric furnace, annealing for 3 hours, and cooling to room temperature along with the furnace;
taking out the finished product: and disassembling the die and taking out the optical fiber preform.
2. The method of fabricating an optical fiber preform according to claim 1, wherein the structure of the through-holes is matched to the core structure of the desired preform.
3. The method of manufacturing an optical fiber preform according to claim 2, wherein the top mold bottom end and the barrel mold top end have a boss and a groove engaged with each other.
4. The method of manufacturing an optical fiber preform according to claim 3, wherein a supporting space is provided on the supporting mechanism, and a second annular flange for being engaged with the supporting space is provided on the outer peripheral wall of the tip end of the cylindrical mold.
5. The method of manufacturing an optical fiber preform according to claim 4, wherein the bottom of the step-like structure penetrates through the bottom wall of the bottom mold, and a substrate for sealing the bottom of the step-like structure is provided on the lifting table.
6. The method of manufacturing an optical fiber preform according to claim 5, wherein the solidified clad glass in the bottom mold is recovered after the bottom mold is removed.
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| CN107311444A (en) * | 2017-07-11 | 2017-11-03 | 中国科学院上海光学精密机械研究所 | The pressurizing unit and preparation method of preform |
| CN114538767A (en) * | 2022-03-30 | 2022-05-27 | 中国计量大学 | A kind of optical fiber preform forming device and forming method thereof |
| CN115677206A (en) * | 2022-11-14 | 2023-02-03 | 中国计量大学 | Preparation device and preparation method of cladding sleeve for optical fiber preform |
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| JP3267073B2 (en) * | 1994-11-01 | 2002-03-18 | 松下電器産業株式会社 | Method of molding optical element and molded optical element |
| JP2566128B2 (en) * | 1995-09-04 | 1996-12-25 | 日本電信電話株式会社 | Mold for manufacturing preform for optical fiber and method for manufacturing preform for optical fiber using this mold |
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| CN107311444A (en) * | 2017-07-11 | 2017-11-03 | 中国科学院上海光学精密机械研究所 | The pressurizing unit and preparation method of preform |
| CN114538767A (en) * | 2022-03-30 | 2022-05-27 | 中国计量大学 | A kind of optical fiber preform forming device and forming method thereof |
| CN115677206A (en) * | 2022-11-14 | 2023-02-03 | 中国计量大学 | Preparation device and preparation method of cladding sleeve for optical fiber preform |
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