Background technology
Optical fiber is drawn in proportion by preform and forms, and prefabricated rods is made up of specific refractory power higher sandwich layer and the lower covering of specific refractory power usually.Because the optical signal more than 99% all transmits in sandwich layer, so the manufacturing technology of plug has determined the optical characteristics of preform.As one of manufacture method of optical fiber prefabricated rod mandrel, axially gas deposition (VAD) method (as application number be 10/142466, publication number is the U.S. Patent application of US 6923024B2, application number is 10/142689, publication number is the U.S. Patent application of US6928841B2, application number is 200610142065.5, publication number is the Chinese patent application of CN1994945A) be the glass granules that combustion reactions generates to be deposited to vertical kinds rod that rotation rises go up and form the body that loosens, has the sedimentation effect height, cost is low, is easy to advantages such as extensive manufacturing.
In recent years, along with the growth of optical fiber demand and the aggravation of competition, the prefabricated rods that need make the large-size specification under the prerequisite that does not reduce the prefabricated rods optical characteristics further reduces cost.Use axial gas deposition to make large size prefabricated rod, need the deposition bigger, that multiple blowtorch that structure is more complicated increases the glass dust, need pressure field and temperature field in the strict control reaction chamber simultaneously.As shown in Figure 1, the device 1 of making preform comprises reaction chamber 2, is used to deposit first blowtorch 3 and second blowtorch 4 of glass dust, is used for fixing vertical anchor clamps 5 of planting rod 9, be used to make vertical plant the rod rotation and promote rotate and upgrade parts 6, exhaust outlet 7 and wind-supplying mouth 8.Make in the process of preform, will vertically plant rod 9 vertical being fixed on the anchor clamps 5 earlier, then with SiCl
4, GeCl
4Gas is delivered to 3,4 burnings of oxyhydrogen flame blowtorch, and hydrolysis at high temperature generates the glass dust.Usually utilize first blowtorch 3 to form sandwich layer 10 at the end of vertically planting rod 9, utilize second blowtorch 4 on sandwich layer 10, to form covering 11 to vertical peripheral part jet flames of planting rod 9 to vertical centre jet flames of planting rod 9.The specific refractory power of sandwich layer 10 is higher than the specific refractory power of covering 11.Vertically plant rod and constantly upwards promote and rotation, thereby obtain the loose uniformly body of external diameter.Loose body forms the transparent plug with sandwich layer and part covering composition through dehydration and vitrifying.
More specifically, unstripped gas (SiCl
4, GeCl
4), inflammable gas (H
2) and combustion-supporting gas (O
2) wait from the raw material supply system and lead to blowtorch with the flow velocity of setting, the H that the oxyhydrogen flame burning produces in unstripped gas and blowtorch
2O hydrolysis reaction takes place or under 1100 ℃ even higher temperature with O
2The direct oxidation reaction takes place generate SiO
2, GeO
2Particulate.Reaction formula is:
SiCl
4+2H
2O→SiO
2+4HCl
SiCl
4+O
2→SiO
2+2Cl
2
GeCl
4+2H
2O→GeO
2+4HCl
GeCl
4+O
2→GeO
2+2Cl
2
The SiO that flame produces
2, GeO
2Particle swims in the flame, forms aerosol.When aerosol particles was present in the even gas of temperature distributing disproportionation, particle can be moved toward the low temperature place by the high temperature place by ordering about of thermograde, and this phenomenon is called thermophoresis.Since the effect of thermograde, SiO
2, GeO
2Particulate is along with the hot gas from the ejection of blowtorch mouth floats on the relatively low loose body of temperature together.The loose vital sandwich layer end face of bulk-growth temperature is utilized the monitoring of infrared laser detecting device, and by controlling the H of sandwich layer blowtorch
2Flow regulate loose body end face temperature (as application number be 10/131700, publication number is the U.S. Patent application of US 6834516B2).
In the loose body deposition process, the negative pressure that exhaust outlet 7 produces is with the waste gas in the reaction chamber 2 and do not deposit to glass dust on the loose body and pump in the middle of the waste discharge pipeline.Reaction chamber 2 reaches pressure equilibrium by wind-supplying mouth 8 additional uncontaminated airs simultaneously.Thereby guaranteed the normal circulation of total system gas, made waste gas can leave reaction chamber 2 fast and avoided chemical substances such as HCl to be diffused into reaction chamber 2 inwalls causing erosion.On the other hand, gas flow has certain cooling effect to the surrounding environment of prefabricated rods, has increased thermograde, has strengthened sedimentation effect, and more glass dust is attached on the loose body.Yet what enter wind-supplying mouth is the air that is in room temperature state, owing to can making air themperature, reasons such as day and night temperature have certain difference, cause the fluctuation of torch flame and prefabricated rods sandwich layer end face temperature, the fluctuation of end face temperature changes the component that deposits to the glass dust on the loose body, and the density of loose body also may change simultaneously.Along with the loose body of prefabricated rods constantly upwards promotes, the sandwich layer size on the loose body length direction also changes thereupon, thereby causes the ununiformity of prefabricated rods axial growth, makes the axial Bao Xin of prefabricated rods produce fluctuation than (ratio of inner cladding and sandwich layer diameter).
Summary of the invention
The technical problem that the present invention at first will solve and the technical assignment of proposition are to overcome the lifting along with the loose body of prefabricated rods that prior art exists, the prefabricated rods axial growth is inhomogeneous, make the axial Bao Xin of prefabricated rods than the defective that produces fluctuation, a kind of device of making preform is provided.For this reason, the present invention adopts following technical proposals:
A kind of device of making preform, it comprises:
One has vertical reactor of planting rod, this reacting appliance chamber that responds;
Be arranged on and be used in the described reaction chamber glass dust that the unstripped gas flame hydrolysis generates is deposited to described vertical at least one blowtorch that rod is gone up the loose body of formation of planting;
Be used to discharge the waste gas in the described reaction chamber and do not deposit to the exhaust outlet of the glass dust on the loose body and the wind-supplying mouth that is used in described reaction chamber, replenishing clean air;
It is characterized in that for described wind-supplying mouth disposes can be with the gas heater of temperature supply gas in described reaction chamber of setting; Described gas heater comprises housing, at least one heating member that is arranged on enclosure interior, the temperature sensor that is arranged on the measurement gas temperature at air outlet place with blast inlet and air outlet, the temperature control unit that is used for regulating according to the temperature that records heating member power, described housing is connected on the described reactor and makes described air outlet corresponding with wind-supplying mouth, described temperature sensor is connected with described temperature control unit, and described temperature control unit is connected with described heating member.
The technical problem of its less important solution of the present invention and the technical assignment of proposition are to overcome the lifting along with the loose body of prefabricated rods that prior art exists, the prefabricated rods axial growth is inhomogeneous, make the axial Bao Xin of prefabricated rods than the defective that produces fluctuation, a kind of method of making preform is provided.For this reason, the present invention adopts following technical proposals:
A kind of method of making preform, be to have at one vertically to plant rod and be provided with in the reaction chamber of reactor of exhaust outlet and wind-supplying mouth, burn by blowtorch, the glass dust of unstripped gas flame hydrolysis generation is deposited to the excellent loose body of formation of going up of vertical kind that constantly makes progress and promote and rotate, it is characterized in that: in the loose body of described formation, to the temperature supply gas of described reaction chamber, make the interior temperature field of described reaction chamber stable by described wind-supplying mouth to set;
For described wind-supplying mouth configuration gas heater makes clean air remain on the temperature of setting so that additional clean air in described reaction chamber is heated;
One housing that has blast inlet and an air outlet is set in described wind-supplying mouth, in this enclosure interior at least one heating member is set between described blast inlet and air outlet, the temperature sensor of measurement gas temperature is set at the air outlet place, the temperature that records according to this temperature sensor is set regulates the temperature control unit of heating member power, described temperature sensor is connected with described temperature control unit, and temperature control unit is connected with heating member and forms described gas heater.
The present invention has following function and effect:
(1) makes the air that enters in the reaction chamber from wind-supplying mouth remain the temperature of setting, thereby obtain Bao Xin, improve the sedimentation effect of loose body than stable preform.
(2) temperature control unit can be regulated the power of heating member automatically according to the temperature of the temperature sensor measurement at air outlet place, guarantees that air outlet provides the hot blast of design temperature, has reduced to enter into the temperature fluctuation of reaction chamber gas.
(3) heated air enters reaction chamber, can improve the temperature in the reaction chamber, saves to be used to heat the inflammable gas of loose surface and the amount of combustion-supporting gas.
(4) flow deflector has rectifying action, can make gas heater 24 interior effluent airs be stable, uniform laminar flow regime, eliminates the phenomenon of air turbulence in the reaction chamber.Thereby reduced not sedimentary SiO
2, GeO
2Particulate is attached to the possibility of reaction chamber inwall.
Other feature and advantage of the present invention can be from below in conjunction with will more fully representing the description of the drawings.
Embodiment
Below in conjunction with accompanying drawing technical scheme of the present invention is described further.
The device of manufacturing preform of the present invention, it comprises:
One has vertical reactor of planting rod 9, this reacting appliance chamber 2 that responds;
Be arranged on and be used in the reaction chamber 2 of reactor the glass dust that the unstripped gas flame hydrolysis generates is deposited to vertical at least one blowtorch 3,4 that forms loose body on the rod 9 of planting;
Be used to discharge the waste gas in the reaction chamber 2 and do not deposit to the exhaust outlet 7 of the glass dust on the loose body and the wind-supplying mouth 8 that is used in reaction chamber 2, replenishing clean air;
Especially for wind-supplying mouth 8 disposes can be with the gas heater 24 of temperature supply gas in reaction chamber 2 of setting.The device of this manufacturing preform makes the air that enters in the reaction chamber 2 from wind-supplying mouth 8 remain the temperature of setting, thereby obtains Bao Xin than stable preform, improves the sedimentation effect of loose body.
As to further the improving and replenishing of technique scheme, the present invention also comprises following additional technical characterictic, so that select for use when stating technical scheme on the implementation:
At first, gas heater 24 comprises housing 13, at least one heating member 14 that is arranged on housing 13 inside, the temperature sensor 15 that is arranged on the measurement gas temperature at air outlet 23 places with blast inlet 12 and air outlet 23, the temperature control unit 16 that is used for regulating according to the temperature that records heating member power, housing 13 is connected on the reactor and makes air outlet 23 corresponding with wind-supplying mouth 8, temperature sensor 15 is connected with temperature control unit 16, and temperature control unit 16 is connected with heating member 14.
At this moment,
The coil rack 18 that heating member 14 is made by insulating material, be wrapped in the nichrome wire 19 on the coil rack 18 and be centered around coil rack 18 and nichrome wire 19 around insulating sleeve 20 constitute, and be formed with gas via-hole 21 in these heating member 14 inside, concrete, the cross section of coil rack 18 is cruciform or M shape, thereby forms gas via-hole 21 between coil rack 18 and insulating sleeve 20; Insulating material is pottery or mica.
Gas heater 24 air outlets 23 places are provided for making gas to produce the flow deflector 17 of stably stratified flow, parallel vertically housing 13 inside that are distributed in of flow deflector 17, and identical at interval.
Gas heater 24 blast inlets 12 places are provided with can gas-pervious protective guard 22, and this protective guard 22 is removably mounted on the housing 13.
Secondly, the device of this manufacturings preform also comprise be used for fixing vertical plant the anchor clamps 5 of rod 9 and be used to make vertical plant rod 9 rotations and lifting rotate and upgrade parts 6.
The explanation of Fig. 2 signal the preferred embodiment of the present invention with the device of axial vapor deposition method manufacturing preform.The device 1 of this manufacturing preform comprises: the reactor that has reaction chamber 2, first blowtorch 3 and second blowtorch 4 that are respectively applied for loose body sandwich layer 10 of deposition prefabricated rods and covering 11 (have provided the situation of two blowtorch among Fig. 2, but also can use a blowtorch or deposit loose bodies) more than two blowtorch, be used for fixing vertical anchor clamps 5 of planting rod 9, be used to make vertical plant rod 9 rotations and promote rotate and upgrade parts 6, being formed on being used on the reactor discharges the waste gas in the reaction chamber 2 and does not deposit to the exhaust outlet 7 of the glass dust on the loose body and the wind-supplying mouth 8 that is used for additional clean air to reaction chamber 2 in, is the gas heater 24 that wind-supplying mouth 8 disposes; Gas heater 24 wherein comprises housing 13, the heating member 14 that is arranged on housing 13 inner axial direction dues, the temperature sensor 15 that is arranged on the measurement gas temperature at air outlet 23 places with blast inlet 12 and air outlet 23, the temperature control unit 16 that is used for regulating according to the temperature that temperature sensor 15 records heating member 14 power.
As shown in Figure 3, housing 13 inwalls are provided with the thermal insulation layer (not shown), at housing 13 1 ends the protective guard 22 with breather hole are installed, and housing 13 the other ends are used for being connected with reaction chamber 2 and being positioned at above two blowtorch.Heating member 14 is installed in the housing 13 near air outlet 23 places, the coil rack 18 that heating member 14 is made by insulating material, be wrapped in the nichrome wire 19 on this coil rack 18 and be centered around coil rack 18 and the insulating sleeve 20 of nichrome wire 19 outer periphery constitutes, leave gas via-hole 21 in the middle of the heating member 14 and makes the air communication mistake.Coil rack 18 cross sections are cruciform, are made of two insulated substrates, and substrate thickness is between 0.5~3mm.Coil rack 18 cross sections also can adopt M shape, but are not limited thereto.Uniform groove on the coil rack 18, nichrome wire 19 with around mode be not positioned in the groove in regular turn overlappingly.Insulating material is pottery or mica preferably.Nichrome wire 19 is made by the Ni-Cr alloy.The external diameter of insulating sleeve 20 is slightly less than the internal diameter of housing 13, so insulating sleeve 20 is fixed on housing 13 inside, can reduce scattering and disappearing of heat.Temperature sensor 15 is arranged at air outlet 23 places of gas heater and is connected to temperature control unit 16, and temperature control unit 16 is connected on the heating member 14.Temperature control unit 16 mainly is to be made of a reaction circuit and a comparer.Behind design temperature, temperature sensor 15 can be measured draught temperature, and when the air outlet temperature was lower than design temperature, temperature control unit 16 can strengthen heating member 14 power, otherwise then reduce heating member 14 power or stop heating, make gas temperature reach design temperature.General, the fluctuating range that enters the gas temperature of reaction chamber 2 from gas heater is controlled in 1 ℃, and with this reference as design temperature.Gas heater 24 air outlets 23 places are provided for making gas to produce the flow deflector 17 of stably stratified flow.As shown in Figure 4, all there is the gap that air communication is crossed sheet flow deflector 17 equally spaced parallel vertically housing 13 inside that are distributed in of long strip shape between the adjacent flow deflector 17, and flow deflector 17 can freely be removed.Heated gas enters reaction chamber 2 along parallel plate, because flow deflector 17 is uniformly distributed in air outlet 23, therefore can produce stable laminar flow hot blast.Gas heater 24 blast inlets 12 places are provided with can gas-pervious protective guard 22, and this protective guard 22 is removably as by screw or be threaded and be installed on the housing 13.
Gas heater 24 links to each other with wind-supplying mouth 8, air outlet 23 communicates with wind-supplying mouth 8, and the wind-supplying mouth 8 of gas heater is positioned at the top near blowtorch 4, is 50~200mm with respect to covering blowtorch mouth vertical range, and exhaust outlet 7 is positioned at the opposite side of reaction chamber 2, and is relative with wind-supplying mouth 8.Make pressure-controlling in the reaction chamber 2 at-100Pa (100Pa by exhausting to air draft air port 7, promptly less than standard atmospheric pressure 100Pa) about, air outside adds to by gas heater 24, wind-supplying mouth 8 and forms air-flow in the reaction chamber 2, can be in time with the SiO that does not deposit on the loose body
2, GeO
2Particulate emission prevents that to exhaust pipeline it from depositing on reaction chamber 2 inwalls.Also help simultaneously the heat that two blowtorch combustion reactionss produce is in time taken away,, increase the thermograde on torch flame and prefabricated rods surface, strengthen thermophoresis efficient to reduce prefabricated rods envrionment temperature on every side.Need to prove that in order to guarantee product purity, the air outside requirement is the uncontaminated air more than 10000 grades.The size of wind-supplying mouth 8 can be according to the size of reaction chamber 2 and required air quantity size decision.Usually its cross-sectional area is at 0.05~0.3m
2Between.
In the prefabricated rods deposition process, ambient atmos enters gas heater 24 under suction function, flows along heating member internal gas through hole 21, takes away the high temperature heat that nichrome wire 19 is produced, and makes to be heated the gas temperature rising, and heated air enters into reaction chamber 2.Therebetween, temperature control unit 16 is according to the automatic adjustments of gas well heater of the signal output rating of the temperature sensor 15 at air outlet 23 places, the gas of air outlet 23 is controlled at design temperature, thereby produces Bao Xin than uniform prefabricated rods.
Fig. 5 is the synoptic diagram of the present invention with another embodiment of the device of axial vapor deposition method manufacturing preform.Fig. 6 is the cross-sectional structure synoptic diagram of gas heater 24 air outlets of the device of manufacturing preform shown in Figure 5.In the present embodiment, the parts of gas heater 24 and Fig. 2, embodiment shown in Figure 3 are basic identical, but air outlet is positioned at the both sides of blowtorch 3,4, and cross-sectional shape is a rectangle.The gas heater 24 that adopts two identical gas heaters 24 or have two air outlets is mended wind to reaction chamber, be combined in the rectangle air outlet that scope is bigger on the short transverse simultaneously, can take away the glass dust that does not more deposit on the loose body effectively.
Fig. 7 is the cross sectional representation of the present invention with another structure of the heating member of the device of axial vapor deposition method manufacturing preform.Among the figure, other parts and Fig. 2, embodiment shown in Figure 3 are identical except heating member.Have only a heating member among the embodiment shown in Figure 3 in the gas heater 24, and a plurality of heating members have been installed in the present embodiment.Be wound with nichrome wire 19 on the criss-cross insulated coil skeleton 18, coil rack 18 and nichrome wire 19 are fixed on and constitute a heating member in the insulating sleeve 20.7 same heating members are installed in housing 13 inside equably, and extraneous air is by the heating of through hole 21 heated objects.Adopt this device, gas heating is more even, and efficient is higher.
Method of the present invention below is described:
Basic, the method of manufacturing preform of the present invention, be to have at one vertically to plant rod 9 and be provided with in the reaction chamber 2 of reactor of exhaust outlet 7 and wind-supplying mouth 8, burn by blowtorch, the glass dust that the unstripped gas flame hydrolysis is generated deposits to the loose body of formation on the continuous vertical kind rod 9 that upwards promotes and rotate, especially: when forming loose body, to the temperature supply gas of reaction chamber 2, make reaction chamber 2 interior temperature fields stable to set by wind-supplying mouth 8.
As to the improving and replenishing of aforesaid method, also comprise following additional technical characterictic:
By disposing gas heaters 24 for wind-supplying mouth 8 to make clean air remain on the temperature of setting to the clean air heating that replenishes in reaction chamber 2, realization response cavity temperature field is stable.Gas heater 24, be by a housing 13 that has blast inlet 12 and an air outlet 23 is set in wind-supplying mouth 8, the heating member 14 of at least one is set between blast inlet 12 and air outlet 23 in these housing 13 inside, the temperature sensor 15 of measurement gas temperature is set at air outlet 23 places, the temperature that records according to temperature sensor 15 is set regulates the temperature control unit 16 of heating member power, temperature sensor 15 is connected temperature control unit 16 formation that is connected with heating member 14 with temperature control unit 16.Further, being provided for making gas to produce the flow deflector 17 of stably stratified flow and be arranged at blast inlet 12 places at air outlet 23 places can gas-pervious protective guard 22.Make coil rack 18 with insulating material, on coil rack 18, twine nichrome wire 19 and around coil rack 18 and nichrome wire 19, constitute heating member 14 around insulating sleeve 20, and at these heating member 14 inner gas via-holes 21 that form.
The wind speed of wind-supplying mouth 8 is controlled between 3m/s~20m/s.When wind speed during, may cause not sedimentary particulate can not give off reaction chamber 2 effectively less than 3m/s.Because wind-supplying mouth 8 is facing to the loose body of prefabricated rods, thus the external diameter fluctuation that may cause loose body to rock during greater than 20m/s to cause in the deposition process when wind speed.
As an example, use device shown in Figure 2 to make the loose body of preform.Venting port 7 is connected with the air exhauster (not shown), and air exhauster is bled, and making pressure in the reaction chamber 2 is negative pressure (as-100Pa, promptly less than standard atmospheric pressure 100Pa).Gas heater 24 work this moment, extraneous air enters reaction chamber 2 by gas heater 1 under suction function, and the gas in question response chamber 2 reaches design temperature and keep constant temperature after 100 ℃.To vertically plant rod and 9 be installed on the anchor clamps 5, and make first blowtorch 3 aim at the lower end of vertically planting rod 9, and plant rod 9 and at the uniform velocity rotate with the speed of 30rpm.Feed hydrogen and oxygen to first blowtorch 3, second blowtorch 4 respectively then, light first blowtorch 3 and second blowtorch 4 successively, the sealed reaction chamber makes pressure-controlling about-100Pa.Then feed gas raw material SiCl to first blowtorch 3
4, GeCl
4Make it to take place hydrolysis reaction, produce SiO
2, GeO
2Particle deposition forms sandwich layer 10 in the lower end of vertically planting rod 9, feeds gas raw material SiCl to second blowtorch 4 simultaneously
4Make it to take place hydrolysis reaction, produce SiO
2Particle deposition forms covering 11 around sandwich layer 10, vertically kind rod 9 constantly rotates and promotes, and forms the inside and outside two-layer loose body of prefabricated rods with different refractivity at last.Remain at 100 ℃ (can set certain amplitude as ± 0.5 ℃) owing to mend the wind-warm syndrome degree in deposition process, avoided mending the fluctuation of wind to loose body sandwich layer end face temperature, vertically fluctuation is less for the loose body of the prefabricated rods that produces.In addition, the stable of temperature field can reduce flow perturbation in the reaction chamber, makes loose bulk-growth more stable.Obtain the transparent plug of φ 45 * 1550mm after the loose body process dehydration vitrifying, the Bao Xin ratio is 5.0, core/concentricity error≤4.4mm, non-circularity of cladding≤1.1mm.
Implement method of the present invention with device shown in Figure 5, the performance of products obtained therefrom is not second to implementing the performance of products obtained therefrom of the present invention with device shown in Figure 2.
Although described the preferred embodiments of the present invention in detail, it will be understood by those skilled in the art that, under the prerequisite that does not break away from as the disclosed the spirit and scope of the present invention of claims, be possible to various improvement, interpolation and the replacement of concrete key element.