CN1197799C - Sintering process for manufacturing prefabricated fiber rod - Google Patents
Sintering process for manufacturing prefabricated fiber rod Download PDFInfo
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- CN1197799C CN1197799C CNB021382271A CN02138227A CN1197799C CN 1197799 C CN1197799 C CN 1197799C CN B021382271 A CNB021382271 A CN B021382271A CN 02138227 A CN02138227 A CN 02138227A CN 1197799 C CN1197799 C CN 1197799C
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- sintering
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- prefabricated rods
- optical fiber
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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
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01446—Thermal after-treatment of preforms, e.g. dehydrating, consolidating, sintering
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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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- Organic Chemistry (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
The present invention relates to a sintering technological method for manufacturing an optical fiber prefabricated rod. In the method, that a contraction ratio coefficient k is set and controlled is used for controlling the outside diameter of a finished product rod after sintering, and thus, a certain ratio of an optical fiber master rod and an optical fiber core is obtained. Firstly, a contraction ratio coefficient k value is designed; the sintered optical fiber master rod is tested by a polished rod tester, and the outer diameter of the optical fiber master rod is obtained. The designed value is verified. If the designed value has declination, the K value is amended and is controlled by changing technological conditions comprising parameters, such as a sintering temperature, a traction speed, atmosphere, etc. An actual test result is used for verifying the K value again. Through multiple tests, the gradual approximation method is used for leading test values to be equal to the designed value.
Description
One, technical field
The present invention relates to a kind of method of making the sintering process of preform, be used for the sintering of the loose body behind the optical fiber prefabricated rod mandrel external sediment.
Two, background technology
The manufacturing of preform, because the factor of each side such as cost and parameter control, comparatively popular adopts two-step approach exactly at present.Promptly utilize the method that depositing time is long, sedimentation effect is low, control complicated but can accurately control refractive index profile to produce plug; as MCVD, PCVD, VAD etc.; in the plug outside; utilize sedimentation effect to compare again higher, depositing time is short, the simple relatively OVD of control or VAD do loose body surrounding layer; by the sintering process of dehydration and vitreous, can the long female rod of large-scale optical fiber of drawing optical fiber milimeter number to make.
Make both to have obtained the higher refractive index profile of the required tolerance range of Optical Fiber Transmission in this way, can enhance productivity again, reduce production costs.Make in this way, but the length of string of single prefabricated rods can reach 300 kilometers.
The conduction of light is to finish in the core of optical fiber, and in optical fiber parameter, it is exactly core bag ratio that an important parameters is arranged.Core bag ratio=optical fiber external diameter b/ optical fiber core diameter a, the optical fiber external diameter=125um of standard, standard value b/a=13.88.Being reflected on the female rod of optical fiber is exactly the core diameter 2d=13.88 of the external diameter 2D/ optical wand of optical wand.
In two-step approach, before the external sediment, calculate required external sediment amount according to the refractive indices n and the core diameter of plug, in order to the core bag that satisfies optical fiber after female excellent wire drawing than and other a series of waveguide parameters.Because post-depositional loose body prefabricated rods density is less, and a contraction is arranged in densification process, promptly external diameter will diminish.In the sintering process of reality, owing to be subjected to density, the influence of each side such as surface tension, temperature, the variation of this external diameter are actually a unordered change procedure.The variation that this is unordered makes the finished product rod after the actual sintered exceed design in advance on diameter variation, and the core bag that causes optical fiber is than uncontrollable.Therefore,, the female rod of qualified optical fiber can't be produced, also just qualified optical fiber can't be drawn out if this variation is not controlled.
Three, summary of the invention
Finished glass behind sintering rod is compared with loose body prefabricated rods, on length and external diameter, have bigger change and, owing to capillary effect, make the core diameter chap of plug.For the core bag of optical fiber after the effective female excellent wire drawing of control than (125um/9.0um), must the control sintering process in the contraction ratio of barred body.Therefore, the contraction ratio COEFFICIENT K is to need an important parameter designing and control in the sintering process.
The sintering process that the present invention relates to is the critical process in the two-step method making rod technology, is loose body prefabricated rods dehydration and vitreous, makes it to become transparent Vitrea process.The present invention relates generally to the design and the control of the contraction ratio COEFFICIENT K of barred body in the sintering process, by the control to sintering temperature, furnace curve, pulling speed, gas usage etc., reaches the purpose of control contraction ratio COEFFICIENT K.
The first, adopting two-step approach to make the technology of the female rod of optical fiber, at first is to make plug 1, carries out external sediment on the mandrel outer surface then.Loose body prefabricated rods behind the external sediment, as shown in Figure 1, external sediment part 2 is vesicular, and density is very little, and reduces gradually from inside to outside, and mean density is compared with the density 2.2g/cm3 of glass probably at 0.5-0.8g/cm3, has only its 1/3 to 1/4.
The second, loose body prefabricated rods is in sintering oven 7, because the rising of temperature and densification gradually, reduced diameter is calculated the external diameter of finished product rod behind the sintering by theory and be should be loose body diameter
Arrive
Theoretical external diameter is come out by the change calculations of deposition weight and density, and deposition weight is constant before and after the sintering.
Before the sintering:
W＝π(D
1 2-d
2)Lρ
1
W---deposits weight
D
1-post-depositional loose body diameter
The plug heart footpath that d---is initial
L---plug length, the i.e. length of loose body
ρ
1---loose volume density
The external diameter of preform behind the Theoretical Calculation sintering:
W＝π(D
2 2-d
2)Lρ
2
W---deposits weight
D
2---vitreum prefabricated rods external diameter
L---plug length, promptly Vitrea length
ρ
2----Vitrea density 2.2g/mm
3
Can calculate the theoretical external diameter of the female rod of optical fiber behind the sintering
Three, still, owing to be subjected to the influence of each side such as surface tension, sintering temperature, furnace curve, the external diameter of the finished product rod after the actual sintered is bigger than theoretic, and barred body has shortened on length, as shown in Figure 5.In order to obtain required core bag ratio, we inlet coefficient K revises the external diameter of finished product rod after the actual sintered and the difference of Design Theory top external diameter, actual outside diameter=KD
2
Design a K value, typical K gets 1.2 to 1.5, and the female rod of the optical fiber behind the sintering is tested with the optical wand tester, and whether the actual outside diameter of the female rod of the optical fiber of seeing is in the certain limit.
The control of K value is the process of a complexity, and the K value is subjected to the influence of sintering temperature, furnace curve, pulling speed etc., and the K value is the function of sintering temperature, furnace curve, pulling speed etc.
Four, embodiment
1, at first design a K value, as K=1.3, the female rod of the optical fiber behind the sintering is tested with the optical wand tester, obtains the external diameter of the female rod of optical fiber.
2, the checking design load if any deviation, is carried out the correction of K value, and with changing processing condition, promptly parameters such as sintering temperature, pulling speed, atmosphere are controlled.
3, practical test result is verified the K value again.By repeatedly experiment,, test value and design load are equated with the method for approaching gradually.
4, in the one group of K value that obtains, select a suitable K value for use, finish sintering circuit.
Four, Summary of drawings
Fig. 1 represents the loose body prefabricated rods before the sintering.1 expression plug, the loose body of 2 expression external sediments, the sedimentary core of 3 expression MCVD, the sedimentary covering of 4 expression MCVD, 5 expression parent tubes, the loose body layer of 6 expression OVD external sediments.
Fig. 2 represents the loose sintering process of body prefabricated rods in sintering oven.7 expression High Temperature Furnaces Heating Apparatuss, 8 expression sintered pipes, 9 expression inlet mouths, 10 expressions need the loose body prefabricated rods of agglomerating, the finished product rod of 11 expression vitreous states.
Fig. 3 represents furnace curve longitudinally.The typical furnace curve of 12 expression sintering ovens.
Fig. 4 represents to be subjected to the influence of surface tension, furnace curve, pulling speed etc., loose body prefabricated rods contraction change at high temperature.The loose body prefabricated rods of 13 expressions, 14 expressions are by the intermediate of loose body prefabricated rods to vitreous state finished product rod, the vitreous state prefabricated rods that 15 expressions sinter.
The typical case that loose body prefabricated rods changes before and after Fig. 5 sintering.Figure A represents loose body prefabricated rods, 16 expression plugs among the figure A, the sedimentary loose external covering of 17 expression OVD.Variation on the figure B representation theory behind the loose body prefabricated rods sintering, the plug of finished product rod behind the sintering on 18 representation theories among the figure B, the surrounding layer of finished product rod behind the sintering on 19 representation theories.Figure C represents the vitreous state finished product rod after the actual sintered, the plug after the 19 expression actual sintered, the surrounding layer after the 21 expression actual sintered.
Five, specific embodiment
Sintering process, the design of k-factor is contraction and the actual sintered according to the loosening body external diameter of theory calculating The contraction of rear loosening body external diameter, the K value is again the shrinkage ratio coefficient, and is designed. The K value gets 1.2,1.3,1.5 All can. The checking design load, if any deviation, carry out the correction of K value, with the change process conditions, namely sintering temperature, The parameter such as hauling speed, atmosphere is controlled.
The result of actual test verifies the K value again. By many experiments, the method with approaching gradually makes test Value and design load equate.
In the one group of K value that obtains, select a suitable K value, finish sintering circuit.
Sintering is in the container of a sealing, at high temperature finishes sintering, by sintering temperature, furnace temperature branch Cloth curve, hauling speed etc. are finished.
Change processing condition, i.e. the process implementing example of similar Fig. 4-5 controlling of parameters such as sintering temperature, pulling speed, atmosphere.Existing technology is: will deposit good loose body prefabricated rods with the speed rotation of 5-10rpm and hang in the sintered pipes, sintered pipes has and is used to protect prefabricated rods not contaminated, makes the functions such as sintering of the stable and safety of barred body.Sintered pipes is as for the center of the electric furnace 10 that evenly heats around Si-Mo rod.Furnace temperature is warmed up to earlier about 1100-1200 ℃, allows dry gas, the mixture as the gases such as helium of the chlorine of 0.6lpm and 2lpm slowly dewaters approximately 1-3 hour from the bottom to top by prefabricated rods.Temperature is raised to 1400-1600 ℃ then, increases the flow of chlorine and helium, carry out sintering, allow loose SiO2 particle fusion at high temperature, discharge gas inside, loose like this body has just become transparent glass preform 11.Under send about the nearly 6-12mm/min of speed and also can.
Typical case
1, plug that MCVD gets off, external diameter is 20mm, and core diameter is 4.2mm, and the plug useful length is 1m.Requirement according to fiber cores bag ratio is calculated, and the external diameter of preform should be 58.30mm behind the sintering.Therefore depositing weight is 6.5kg, and the loose body diameter in deposition back is 110mm.
2, selected K value, K=1.3, because of the external diameter of preform after must actual sintered is 75.79mm, core diameter is 5.46mm, the useful length of preform is 592mm.
3, select a kind of processing condition for use, furnace temperature is 1550 ℃, and the He consumption is 60L/min, and the Cl2 consumption is 1L/min, and pulling speed is 5mm/min, and rotating speed is 7 commentaries on classics/min, carries out sintering in the container of a sealing.
4, the finished product prefabricated rods behind the sintering detects with the optical wand tester, and the actual outside diameter of test result finished product rod is 74.81mm, and core diameter is 5.39mm, and therefore actual K value is 1.28.Differ 0.02 with design load.
5, after same plug carries out external sediment, change sintering process parameter, furnace temperature is reduced by 10 ℃, the consumption that adds atmospheric respectively reduces pulling speed, and the finished product rod behind the sintering after testing, the external diameter that obtains is 75.38mm, core diameter is 5.43mm, and therefore actual K value is 1.29, differs 0.01 with design load.
6, thresh same test.Change sintering process parameter, furnace temperature is reduced by 15 ℃, gas usage is remained unchanged, pulling speed is reduced 0.3mm once more, simultaneously rotating speed is adjusted into 6.5 commentaries on classics/min.Finished product prefabricated rods behind the sintering after testing, the external diameter that obtains prefabricated rods is 75.80mm, core diameter is 5.46mm.Actual K value and design load are in full accord.
7, therefore select a K value for use, just select a cover appropriate parameters for use, can accomplish that design load and actual value are in full accord, thus the core bag ratio of control preform.
Finish agglomerating under the working control high temperature, increase after the actual sintered loose body diameter or improve sintering temperature and pulling speed reduces loose body diameter after the actual sintered by reducing sintering temperature and pulling speed.This is a common process.
Claims (6)
1. sintering method of making preform, by regulating the external diameter that sintering temperature, furnace curve, pulling speed, speed of rotation, atmosphere are controlled preform after the actual sintered, thereby effectively control the core bag ratio of prefabricated rods, this method is characterised in that:
A) the first step is introduced the contraction ratio COEFFICIENT K, revises the external diameter of prefabricated rods after the actual sintered and the difference of Design Theory top external diameter with K, wherein the theoretical outer diameter D of prefabricated rods behind the sintering that calculates according to formula
2, the external diameter of finished product rod equals KD after the actual sintered
2, the span of K is between 1.2 to 1.5;
B) in second step, set a K value, the prefabricated rods behind the sintering is tested with the optical wand tester, obtains the actual outside diameter of prefabricated rods; K verifies to design load, if any deviation, changes processing condition, and promptly sintering temperature, furnace curve, pulling speed, speed of rotation, atmosphere are carried out next sintering, verify the K value again with practical test result;
C) the 3rd step is by repeatedly experiment, with the method for approaching gradually, test value and design load are equated, can obtain many groups processing condition of one group of K value and their correspondences in this process, the selected processing condition that test value and design load are equated promptly are required sintering process conditions.
2, sintering method as claimed in claim 1, wherein the contraction ratio COEFFICIENT K can be by controlling the adjusting of sintering temperature, furnace curve, pulling speed, speed of rotation, atmosphere.
3, sintering method as claimed in claim 1, wherein the regulation range of sintering temperature is controlled between 1400～1600 ℃.
4, sintering method as claimed in claim 3, sintering temperature uphill process wherein at first make prefabricated rods rest on the stove internal rotation in two steps, and temperature is raised to 1100 ℃～1200 ℃, and loose body was dewatered 1～3 hour; Then temperature is risen to 1400 ℃～1600 ℃, prefabricated rods is sent under slowly, carry out sintering.
5, sintering method as claimed in claim 1, wherein the speed of rotation that adopts in the sintering process is controlled at 5～10 rev/mins.
6, sintering method as claimed in claim 1, wherein the atmosphere of sintering process employing is the mixed gas that helium and chlorine constitute.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021382271A CN1197799C (en) | 2002-09-06 | 2002-09-06 | Sintering process for manufacturing prefabricated fiber rod |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021382271A CN1197799C (en) | 2002-09-06 | 2002-09-06 | Sintering process for manufacturing prefabricated fiber rod |
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| Publication Number | Publication Date |
|---|---|
| CN1482082A CN1482082A (en) | 2004-03-17 |
| CN1197799C true CN1197799C (en) | 2005-04-20 |
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| CNB021382271A Expired - Fee Related CN1197799C (en) | 2002-09-06 | 2002-09-06 | Sintering process for manufacturing prefabricated fiber rod |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102092936B (en) * | 2010-12-29 | 2013-02-06 | 烽火通信科技股份有限公司 | Preparation method of optical fiber preform |
| CN106904821B (en) * | 2017-02-15 | 2019-03-22 | 天津富通集团有限公司 | The production technology and its large-scale optical fiber prefabricating stick of large-scale optical fiber prefabricating stick |
| CN110790501A (en) * | 2019-11-22 | 2020-02-14 | 青海中利光纤技术有限公司 | Sintering device and method for optical fiber preform |
| CN114326859B (en) * | 2021-12-29 | 2023-03-31 | 江苏南方光纤科技有限公司 | Optical fiber preform speed-raising die holder temperature control method, computer medium and computer |
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Granted publication date: 20050420 Termination date: 20130906 |