CN1169542A - Apparatus and method for forming optical fiber coating - Google Patents

Abstract

An apparatus and method for coating an optical wave guide fiber with a liquid polymer coating includes pressurizing a chamber with a process fluid and venting the process fluid along, and in a direction opposite the direction of travel of, the incoming fiber, to strip particles from the incoming fiber before the particles enter the die assembly.

Description

Form the apparatus and method of optical fiber coating

The present invention relates to the coating of optical fiber, the material of coating the time is a liquid in coating, solidifies then and form solid protectiveness organic coating on optical fiber.More specifically, the present invention relates to improved apparatus and method, the decreased number of number, the especially particulate inclusions of snotter in the organic coating wherein improving the quality and the integrality of solidifying the back protective finish, thereby improves the performance of final products.

The way of the liquid organic coating of coating is on record on light transmitting fiber for the cover glass fiber prevents to damage.The typical light transmitting fiber of producing comprises the glass fiber based on silicon dioxide at present, is coated with the acrylate coatings of two-layer protection usefulness.Glass fiber plays a part waveguide, and the pulling strengrth of the optical fiber overwhelming majority is provided.Acrylate coatings is then avoided damaging because of abrasion and/or external carbuncle in order to cover glass in manufacture process and when using in the open air.In order to prevent to damage in manufacture process, coating is in the well coating immediately before fiber and other surperficial contact later on of glass fibers Wella.Optical fiber draws with more and more higher speed, the device of coating protective finish must be under this higher fibre-optical drawing speed the high-quality coating of upgrading.

A problem that runs into when the high speed coated glass fiber can be introduced the snotter of particle and so in polymer coating.Snotter can make the mechanical property of coating descend, thereby optical fiber properties is had a negative impact.

For example, when having snotter in the coating, the hot expansibility difference of glass fibre and coating is very big, and problem will take place.By the homogeneous thermal expansion of fiber and coating with shrink and cause and stretch and the simple homogeneous state of stress that compression is produced, fibre-optic light transmission and strength characteristics be there is no have a strong impact on.But,, will in coating and glass fibre, all produce the bending stress of concentrating owing to differential expansion that has snotter to cause in the coating or contraction.These stress will all have a negative impact to the photoconduction performance and the strength character of fiber under extreme temperature conditions.

Have in coating under the situation of particle contamination, prior problem is to have such possibility: particle contacts with glass fibre and causes crackle, fiber is ruptured immediately or increases until destruction when further handling.The particle that pollutes normally is base with silicon dioxide, so they have enough hardness, is easy to scratch or penetrate glass fibre.Fault analysis to optical fiber shows have particle to be embedded in the primary coating of glass surface.Be in the particle of this position, in the bent process of normal change that interrelates with procedure of processing such as coiling, or in the process that fiber is installed, will in glass, cause surface imperfection.

In typical fiber painting method, glass fibre is directed to the coating mold assemblies immediately after forming.This subassembly comprises a guiding mould, the accumulator of a liquid coating, and a last rubber moulding.Glass fibre is in turn by above-mentioned each parts.Liquid coating sticks to and forms coating on the fiber, and this coating is cured subsequently again.

This method had been done the improvement that some are intended to reduce or eliminate bubble in the coating.For example, can be before fiber be by the accumulator that contains liquid coating, replace the air of entrainment in the optical fiber surface boundary layer with the working fluid (it is to may be dissolved in the liquid coating) of carbon dioxide and so on.Working fluid enters in the liquid coating together in company with fiber, and is dissolved in the coating rather than resembles and form bubble the air.

The visible United States Patent (USP) 4,792,347 of the explanation of this method, this patent has transferred the application's same assignee, and the full content of quoting it here is as a reference.In this system, around the optical fiber of inwardly motion, be equipped with regulon, in order to provide inverted draft to replace the air of entrainment on optical fiber.The interior cylindrical sleeve pipe of this regulon has a plurality of airflow holes, in order to inverted draft is guided on the optical fiber.

Also have the people to introduce working fluid by the groove of cooling device, to form the air-flow that points to optical fiber, as illustrated in U.S. Patent application 08/409,231, this application has transferred the application's same assignee.In this device, use helium to come cooling optical fibers, and come under very high drawing speed, to replace or remove air on the optical fiber with it.Superfluous helium and discharge with the direction of leaving optical fiber by a hole by the air entrainment of disposing on the optical fiber.

Though replace the air of entrainment with soluble working fluid the bubble that reduces in the fibre coating has been produced acceptable result, also trial has been done in other improvement of this method.At United States Patent (USP) 5,127, in 361, the structure of guiding mould and last rubber moulding has been done adjustment, makes it can reduce the number of the bubble that forms under high drawing speed in coating.In this device, adjusted the size in space between guiding mould and the last rubber moulding, and in the hole of last rubber moulding, formed a conical surface, to improve coating procedure.

Another kind of existing mold assemblies is introduced into around the cylindrical bore of that part of optical fiber that moves into the guiding mould working fluid indoor.This thorax chamber is communicating with atmosphere with guiding mould opposing open end, and diameter is about 13mm (0.500 inch).Working fluid is to introduce by near the one or more passages that pass to the thorax chamber guiding mould.Working fluid can be from the openend of thorax chamber to flow out with fibre movement side in the opposite direction.

Though some above-mentioned systems have reduced the defective of liquid applying coating to a certain extent effectively, but still wish and further to improve.The method of at present used coated fiber can not effectively be eliminated the particle contamination of liquid coating.

The invention provides a kind of method and apparatus that can reduce the overlay that optical fiber is polluted.A kind of method of the present invention is, optical fiber fed be equipped with in the accumulator of liquid coating, passes this storage class device and by its pass-out, one deck liquid coating is bonded on the optical fiber.Apply working fluid leading on the optical fiber of accumulator, working fluid is flowed along the optical fiber that feeds, direction is opposite with the direction of fibre movement.

Near the maximal rate of working fluid optical fiber is at least 1.5 meter per seconds.Higher speed can be more effective, as be at least 14 meter per seconds, and more preferably at least 27 meter per seconds are preferably at least 35 meter per seconds.To illustrate below, can use measuring of two kinds of fluid velocities.Real " measurement " speed is represented near the real fluid speed outside the boundary layer of optical fiber." measurement " speed is to record with a kind of instrument that can measure the fluid velocity on the each point in the fluid." theory " maximum fluid velocity is some parameter (as the size in pressure and hole) according to system, by the maximum fluid velocity in the velocity distribution of below equation and the simplification hypothesis of discussion being expected to obtain.Act on the working fluid jet on the optical fiber of feeding, can prevent that particle from entering the liquid coating accumulator.

In the fibre-optical drawing environment, the particle of difficult eliminating is that those are entrained on the optical fiber, the perhaps particle of entrainment in optical fiber surrounding air boundary layer, and these particles move to accumulator with the speed of optical fiber.Preferably the air-flow of fluid (or liquid stream) can repel the density of expecting in the drawing optical fibers environment and size maximum, direction of motion is identical with the direction of motion (" fibre movement direction ") that optical fiber leads to accumulator, and the particle that can compare with the speed of optical fiber itself of speed.To further specify below, the merit that makes its deceleration that working fluid is done particle increases with fluid velocity, and can calculate as size, particle size and the particle density in flow rate, hole according to some parameters of system.If the merit of the deceleration of being done is equal to or greater than the kinetic energy of the particle that moves with optical fiber with the speed of optical fiber, this particle will be ostracised.Each parameter that is preferably working fluid is to be chosen to like this: (general diameter is about 50 microns for the particle that can produce the expection density and the size maximum of practical problems in the fibre-optical drawing environment, density is about the density of silicon dioxide, 2.1 gram/cubic centimetre), particle maximal rate or threshold velocity that air-flow can stop are shifted to the speed of accumulator more than or equal to optical fiber.In other words, the air-flow of working fluid (or liquid stream) should be able to make expection density and size maximum, stops with the particle of optical fiber speed motion.Therefore, the present invention can be reduced in create conditions the down particle contamination of liquid coating of typical case greatly.On the contrary, though think the existing device that around the optical fiber that feeds, applies working fluid now, may make by accident that some are light, the slow particle of motion stops and not entering accumulator, but those structures can not prevent effectively and the particle contamination coating faster of moving big.

Optical fiber is fed the step of accumulator, better is to allow optical fiber pass the thorax chamber inlet enter the thorax chamber, again optical fiber is fed the accumulator that liquid coating is housed by the thorax chamber, passes accumulator then and passes to the optical fiber outlet.The step that applies working fluid preferably includes with the step of working fluid with the pressurization of thorax chamber.Working fluid leaves accumulator and discharges from the thorax chamber inlet, makes working fluid flow along the optical fiber that inwardly moves, and its direction is opposite with the fibre movement direction.As mentioned above, the air-flow of working fluid (or liquid stream) is drawn by the thorax chamber inlet, and its direction is opposite with the fibre movement direction, preferably can before particle enters the thorax chamber inlet it be stopped.The logical step of making fluid of knocking off also can be included at least a portion of thorax chamber and keep flowing of working fluid, and flow direction is opposite with the fibre movement direction, and the maximal rate at the indoor adjacent fiber of whole thorax place is at least 1.5 meter per seconds.Indoor at thorax, maximal rate cans be compared to most above-mentioned higher.Can help to make the particle that is carried through the ingate to stop at the indoor high velocity air of thorax.It is indoor along keeping high velocity air on the segment length quite long on the fibre movement direction to be preferably in thorax.

The thorax chamber preferably has less minimum diameter, even make that the mass flowrate of working fluid is lower, it is required high-speed that the fluid air flow that is penetrated by the optical fiber ingate is had.So working fluid can be lower than per minute 6 standard liters with being lower than the flow rate discharge that per minute 10 standards rise, being more preferably.Working fluid can be that air or helium, carbon dioxide or other can prevent to form the gas of bubble.

Another aspect of the present invention provides a kind of in order to the device to the fiber coating coating.This device comprises a die clamp with inlet end and endpiece, last rubber moulding in abutting connection with endpiece, should go up rubber moulding and define a gluing nib, and the guiding mould between the inlet end of last rubber moulding and die clamp, this guiding mould defines a guiding nib.Guiding nib and gluing nib are coaxial with fiber axis substantially.Last rubber moulding, guiding mould and die clamp define an accumulator between last rubber moulding and guiding mould, in order to receiving fluids coating.This device comprises that also qualification extends between guiding mould and the die clamp inlet end, centers on the device of the thorax chamber of fiber axis.Described thorax chamber is preferably in along the minimum diameter that has on a certain position of fiber axis less than 3.8mm (0.150 inch).There is the workflow body opening to be communicated with this thorax chamber.Optical fiber can move through this thorax chamber and pass accumulator along fiber axis.Working fluid can feed this thorax chamber, and leaves accumulator and discharged by this thorax chamber around optical fiber.

Fig. 1 is the sectional view of die clamp subassembly in one embodiment of the present of invention, and it is corresponding to the section that passes through the I-I line among Fig. 2;

Fig. 2 is another sectional view of die clamp subassembly shown in Figure 1, and it is corresponding to the section that passes through the II-II line among Fig. 1;

Fig. 3 is coating unit shown in Fig. 1～2 and optical fiber with the synoptic diagram in the method coating procedure of the present invention;

Fig. 4 is the synoptic diagram that guides mould and last rubber moulding and light guide optical fiber wherein and liquid coating in Fig. 1～3;

Fig. 5 is the comparison with particle stop distance under various working fluid effluxvelocities of several starting velocities;

Fig. 6 is that the indoor theoretical velocity of thorax distributes under the diameter of several thoraxes chamber;

Fig. 7 is the sectional view of die clamp subassembly in another embodiment of the present invention.

Referring to Fig. 1, shown a die clamp assembly (briefly representing) among the figure with numeral 10, it is used for a kind of coating material is coated on the optical fiber, and fiber axis 112 extends to the bottom by the center of assembly by its top.Die clamp assembly 10 generally comprises gluing die clamper 20 (rubber moulding 21 wherein is housed), guiding die clamper 50 (guiding mould 51 wherein is housed) and die cover 70.

Gluing die clamper 20 is to be substantially columniform parts, and it has a center bore 25, is used for holding the guiding die clamper.There is the bottom surface 33 of a substantially flat in thorax hole 25.The outside surface 36 of gluing die clamper 20 is provided with coating material groove 27, for coating material provides passage.Have inlet hole 26 in the groove 27, groove is linked to each other with center bore 25.Groove 27 and hole 26 are positioned at the place near the bottom surface 33 of center bore 25.

Gluing die clamper 20 also has the center die of a break-through bottom surface 33 that thorax hole 24 is installed.Last rubber moulding 21 preferably is pressed into thorax hole 24 with slight interference engagement.Last rubber moulding 21 has one and goes up rubber moulding center pit 22.The gluing nib can have drainage inclined-plane or fillet 23 towards an end of gluing die clamper 20 inside, to improve the flow characteristics of liquid coating.The light transmitting fiber (not shown) is during by the fixture assembly pass-out, and gluing nib 22 surrounds optical fiber, removes unnecessary liquid coating, forms to have the coating of homogeneous diameter on optical fiber.

Between the coatings tank 27 and its end face 35 of gluing die clamper 20, on the outside surface 36 of gluing die clamper, be provided with operate outside fluid groove 31.Operate outside fluid bore 32 is communicated with groove 31 with the center bore 25 of gluing die clamper.In the gluing die clamper of Fig. 2, shown 4 operate outside fluid bore 32, but the number in hole can be less or some more.

See Fig. 1 again, guiding die clamper 50 is one and is substantially columniform parts that the size of its outside surface 58 can critically be snug fit in the center bore 25 of gluing die clamper it.When each die clamp assembled, the head 56 of guiding die clamper 50 was located on the end face 35 of gluing die clamper.

The bottom surface 54 of guiding die clamper constitutes an accumulator 66 with the bottom surface 33 of center bore 25 and gluing die clamper, in order to deposit the liquid coating that coated fiber is used.Guiding mould 51 preferably is pressed in the hole of guiding die clamper 50 bottom surfaces 54 with slight interference engagement.A guiding mould center pit 60 and lead-in chamfered or fillet 52 are arranged on the guiding mould 51, and lead-in chamfered is positioned at the side away from accumulator 66.It is concentric with gluing nib 22 basically that the position of related features of guiding mould, guiding die clamper, last rubber moulding and gluing die clamper should be able to guarantee to make guiding nib 60.

Center pit or thorax 53 extend on the guiding die clamper 50 other end relative with guiding mould 51 by guiding mould 51 along the fiber axis 112 of guiding die clampers 50.Can there be lead-in chamfered or fillet 57 in end at guiding die clamper 50, so that help when starting work optical fiber is penetrated central bore 53.

On the outside surface 58 of guiding die clamper 50 internal work fluid groove 54a is arranged, align with the operate outside fluid bore 32 on the gluing die clamper 20.Also be provided with internal work fluid bore 55 on guiding die clamper 50,54a is communicated with thorax chamber 53 with internal work fluid groove.Though shown four internal work fluid bore 55 among Fig. 2, more or less hole can have been arranged.As shown in Figure 2, guiding die clamper and last glued membrane anchor clamps are to be assembled into rotation displacement, make the misalignment of inside and outside workflow body opening.The position of this misalignment can make working fluid evenly flow into thorax chamber 53.For convenience of explanation, the position of Fig. 1 mesopore 55 has rotated 45 ° with respect to the position of Fig. 2.

Die cover 70 will guide the head 56 of die clamper 50 to be clipped between the end face 35 of the interior shoulder 72 of die cap 70 and gluing die clamper 20.The center pit 73 of die cap 70 is aimed at thorax 53, guiding nib 60 and gluing nib 22, makes all these parts all coaxial with fiber axis 112.In embodiment shown in Figure 1, die cap center pit 73 is slightly less than the diameter of thorax 53, protrudes the position to avoid producing, influences penetrating of optical fiber when starting work.Center pit 73 plays a part to extend thorax 53.So center pit 73 defines the minimum diameter of thorax 53.

Die clamp assembly 10 is contained in the discharge 100, as shown in Figure 3.Discharge 100 has an inlet 102, links to each other with the liquid coating groove 27 of gluing die clamper 20.Inlet 102 is connected in coating source 107, and coating flow to coating inlet 102 by pressure adjustment assembly 105 again through excess temperature holding device (for example well heater 106).So, the liquid coating of coating source 107 can be supplied to accumulator 66, and the temperature and pressure of coating can be controlled accurately in the accumulator.

Discharge 100 also has a Working-fluid intaking 101, links to each other with the operate outside fluid groove 31 of gluing die clamper 20.Workflow body source 104 is connected in Working-fluid intaking 101 by pressure governor 103.Working fluid from fluid source 104 can enter external fluid groove 31 (see figure 2)s, by outer flow body opening 32, flows into the internal work fluid groove 54a of guiding die clamper 50.Working fluid by internal work fluid bore 55, feeds central bore 53 by groove 54a apace then.

According to one embodiment of the present invention, optical fiber 111 along fiber axis 112 by die clamp assembly 10 by the direction of arrow 110 (see figure 3) of advancing.In accumulator 66, keeping liquid coating, making optical fiber during by last rubber moulding 21, clagging will be arranged on optical fiber 111 by conventional draw-gear (not shown) towing.Last rubber moulding 21 is removed unnecessary coating, forms the optical fiber 113 that applies, as shown in Figure 4.

At Fig. 4 as seen, meniscus 114 of liquid coating formation between guiding mould 51 and the optical fiber 111 that advances in accumulator 66.The size and dimension of meniscus 114 depends on the temperature and pressure of the liquid coating that enters accumulator 66, and the size of guiding nib 60.

Preferable liquid coating is the epoxy resin or the urethanes-acrylate of available ultraviolet light polymerization.In the present embodiment, working fluid is a carbon dioxide preferably, because it is cheap and dissolve in described liquid coating.When working fluid is flowed out by internal work fluid bore 55 and during by central bore 53, workflow is known from experience and is entrained on the optical fiber 111 that enters assembly, with the border air layer on the optical fiber that moves closer to all or major part replace.It is believed that because working fluid is soluble in coating than air, such replacement can reduce the bubble in the coating of the optical fiber of making, though the present invention is not subjected to the restriction of this theory.

Enter the working fluid in the die clamp assembly, most of must be by central bore 53, around the optical fiber 111 that enters assembly, flow out, as shown in Figure 3.The size and the structure of the inlet 75 by control thorax 53 and thorax, can regulate the velocity distribution of the working fluid by thorax 53 and outside central bore inlet 75 velocity distribution of working air current 150, prevent that particle from entering the die clamp assembly and polluting liquid coating.In essence, at one significant air-flow of inside and outside formation of thorax, the direction with fibre movement on its direction opposite (in Fig. 3 be upwards direction), from around float into or the particle that is involved in the optical fiber boundary layer blow off.

As shown in Figure 3, the working fluid of outflow forms axisymmetric jet-stream wind (briefly representing with label 150 among the figure) above central bore inlet 75.The total flow direction of jet-stream wind 150 is opposite with fibre movement direction 110.Flow out the working fluid 150 of central bore inlet 75, its velocity distribution 151,152,153 has maximal value near the heart therein, and the optical fiber that enters assembly promptly is positioned at this center.The momentum of the airflow that the optical fiber that can contend with is at a high speed like this carried secretly, the particle that prevents to twist in the optical fiber boundary layer enters die clamp assembly 10.And the high-velocity tube distributions in the central bore 53 can purge the particle in the die clamp assembly from thorax 53.

Be to be understood that, velocity distribution 151,152 and 153 is theoretical figures, they are to make on the hypothesis air-flow is deferred to the basis of theory flow mode of " free jet-stream wind ", and " free jet-stream wind " promptly is to penetrate to the air-flow of surrounding medium (air) under the condition that does not have other solid constraint from mouth 75.Shown velocity distribution does not reflect the influence to optical fiber.

Equation by air-flow in the appraisal domination thorax 53 and the jet-stream wind 150 outside the central bore inlet 75, can calculate the Peak Flow Rate of working fluid, will stop at the maximal rate of the incident particle of central bore inlet, and enter the mouth when mobile the quantity of the given particle of 150 pairs one of jet-stream winds institute work done when particle to central bore.Utilize these parameters, can expect the performance of a certain die clamp modular construction.

At first, determine that particle weight equals the equilibrium condition to upper pulling force that working fluid produces, and just can make preventing that the given particle from floating into the required flow velocity of die clamp assembly.Suppose that diameter is 50 microns a spherical silica particle, and 50 microns is to finding to be clipped in the diameter of the largest particles in the fibre coating in the research of current methods.The weight of particle is:

Wherein the radius of a ball R of particle is 25 microns, and density p grain is 2100 kilograms/cubic metre.The pulling force that acts on the particle can be determined by reynolds number Re and the towing coefficient Cd that at first calculates as the function of working fluid speed V:

$\mathrm{Cd}=\frac{24}{\mathrm{Re}}+\frac{6}{(1+\sqrt{\mathrm{Re}}}+0.4$

Working fluid (is assumed to CO ₂) kinematic viscosity v _GasBe 610 ^-6m ²/ second, its density p _GasBe 1.5kg/m ³The ream weight amount equates just to obtain equilibrium condition with pulling force:

Use alternative manner, the diameter of sening as an envoy at last is that 50 microns the required carbon dioxide flow velocity of silica dioxide granule suspension is 25.4cm/ second.This equilibrium rate has provided to make does not have the initial particle of momentum downwards to stop the rough Statistics of required air-flow.That is to say that if diameter is 50 microns a silica dioxide granule to be placed on the inlet top and not to move downward, the carbon dioxide gas stream with 25.4cm/ second can make this particle suspending in air.

But when drawing optical fiber, the particle of entrainment in the optical fiber boundary layer has momentum, prevent that particle from entering the die clamp assembly and polluting coating, must offset this momentum.In typical method for drawing optical fibers, optical fiber and very fast speed enter inlet 75, and its speed is generally greater than 10m/sec.The particle of entrainment in the optical fiber boundary layer also moves with this speed approx.So the air-flow of the working fluid by the thorax chamber must be set up an airflow field, this airflow field is made enough merits to particle and its direction is reversed.So staring at the attenuation of inlet 75 when stretching out by the center, jet-stream wind 150 just becomes very important.

Below provide and describe the governing equation that particle passes through jet-stream wind 150 and passes through the motion of thorax 53.At first, in the thorax 53 in the speed of air-flows and the thorax radially the funtcional relationship of position y be:

Wherein the radius of thorax is γ _o, working fluid is Q by the volume flow rate of thorax 53.Fig. 6 has provided the Velocity Profiles figure in the thorax 53 under several thoraxes or the hole dimension.As seen from Figure 6, when the size in hole hour (for example 0.100 inch), near its speed of thorax wall place when bigger than hole dimension (for example 0.170 inch) increase soon, and the hole when big velocity distribution more smooth.So, enter particle in the thorax near the thorax wall and hour more may be ostracised in the hole.In addition, the maximal rate of working fluid occurs in the centerline of thorax, and this place particle by entrainment in the optical fiber boundary layer.The size in hole hour, center line velocity is higher.The theoretical largest tube speed of the pipe distributions centerline in thorax is:

Herein, " theoretical largest tube speed " is meant the theoretical maximal rate at center line, be the thorax that passes through when working fluid discharges the diameter least part by equation (1) calculate." theoretical maximal rate " promptly is theoretical largest tube speed except as otherwise noted, herein.In the embodiment of Fig. 1, central bore inlet 75 is determined the part of thorax diameter minimum.This diameter has determined the degree of functioning of thorax 53 aspect the repulsion particle.Shown among Fig. 6 that under one group of given flow parameter the theoretical largest tube speed under several different thorax hole dimensions promptly is to equal the maximal rate that O (that is tube hub) locates in radial position.It is the measured maximal rate of part in thorax interior diameter minimum that another of degree of functioning measured, and this numerical value is to record with a kind of instrument that can not disturb fluid field significantly and record a certain flow velocity.

By the theoretical maximum effluxvelocity in the rotational symmetry jet-stream winds of thorax inlet 75 expansions with have following funtcional relationship from thorax inlet 75 apart from x:

Wherein v gas is the kinematic viscosity of working fluid, U _MzxJet is in the theoretical maximum effluxvelocity of the flow distribution center of jet-stream wind.This is that " far field " of effluxvelocity of center line symmetry is approximate, only sets up on the point of hole one segment distance outside thorax.Suppose that the speed in the jet-stream wind is not more than theoretical largest tube speed, promptly arrives apart from x at jet ^*Before, air-flow has the character of pipe stream, and x ^*Be by formula (2) calculate U _{The mzx jet}(x ^*) equal by formula (1) calculate U _Pipe/maxThe position, calculate the r in the seasonal formula (2) _o(radius of jet-stream wind) equals the radius of thorax porch thorax.For one group of given parameter calculate theoretical maximum effluxvelocity can be used as another of degree of functioning that jet repels particle and measure.

In thorax and in jet-stream wind, spherical silicon dioxide particle is when the air-flow center line of working fluid moves through air-flow, and the pulling force that is applied to it all can be expressed as the function Drag (x) along the coordinate x of fiber axis.At first, will be expressed as the function of x at the reynolds number Re on the line of jet-core region (x) and the towing coefficient Cd (x) that acts on particle:

$\mathrm{Cd}\left(x\right)=\frac{24}{\mathrm{Re}\left(x\right)}+\frac{6}{(1+\sqrt{\mathrm{Re}\left(x\right)}}+0.4---\left(4\right)$

Arbitrary part in thorax, U _MzxBe by the diameter that formula (1) is used this point in the thorax calculate U _{Pipe mzx}And the arbitrary part in jet, U _MzxBe by formula (2) calculate U _{The max jet}The pulling force that is acted on particle by flowing process fluid can be expressed as the function of x:

Determined just Newton second law to be applied to system, to determine under given pulling force function Drag (x), after the power that silica dioxide granule is applied to it when passing working fluid at x ₁To x ₂Distance in the changes delta v of speed:

F＝m·a

F=Drag (x)-(weight) $a=\frac{\mathrm{dv}}{\mathrm{dt}}$ $v=\frac{\mathrm{dx}}{\mathrm{dt}}$ $\&Integral;\mathrm{vdv}=\&Integral;\frac{F}{m}\&CenterDot;\mathrm{dx}$ $\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="A9711039400201.png"\; state="\{\{state\}\}">V</figure-callout>}}^2=\frac{V{\left(x_1\right)}^2}{2}-\frac{V{\left(x_2\right)}^2}{2}=\frac{1}{m}{\&Integral;}_{x_1}^{x_2}F\left(x\right)\mathrm{dx}---\left(6\right)$

Approximate treatment is by x=X _L(the negligible place of the pulling force that jet causes is to entering the mouth 75 distance) to the Δ v of x=0 (porch) through whole jet, just can draw the rapid change Δ v that passes through whole jet _Jet:

Δ v _JetIt also is jet makes its maximal rate that stops before particle enters the thorax inlet estimated value.

Utilize the discrete estimation value of the integration of the above-mentioned power F (x) that acts on particle, can estimate the parameter that some describe the motion of particle in thorax 53.Ignore particle weight (particle speed greater than 5 meters of per seconds time, it is insignificant that weight is compared with pulling force) and calculate, then distance, delta x in thorax and the experience particle speed changes delta v that this distance took place with further simplification _PipeBetween relation, can be expressed as the relative velocity V of particle in working fluid _GasFunction:

ρ wherein _GrainAnd ρ _GasBe respectively the density of particle and working fluid, R is a particle radius, V _GasBe the working fluid speed that begins to locate at Δ x, and Cd is the towing coefficient in pipe stream centerline.Ask for the largest particles speed that in given distance, delta x, can stop after following formula rearranged:

When different parts has different radius Rs on its length x in the thorax chamber, the expression of Δ x and Δ v can be applied to each part of thorax chamber respectively.The simplification of being done in these expressions causes the predicted value of pulling force low excessively; Therefore, the change of speed is lower than actual value, and produces the required distance, delta x of given rapid change greater than actual value.

Working air current arrives the maximum starting velocity Δ of the particle v that can stop before the accumulator of coating fluid at particle _GrainEqual in thorax and air-flow in Δ v sum, that is:

Δ v _Grain=Δ v _Jet+ ∑ Δ v _Pipe(10)

∑ Δ v wherein _PipeBe Δ v through whole thorax chamber (by working fluid introducing place to the thorax chamber inlet) _PipeFor in thorax and any given working fluid in the jet, and for given particle radius and density, just can be by above-mentioned various calculating Δ v _GrainNumerical value.∑ Δ v _PipeAlong with the length of the thorax chamber of carrying working air current (being by the distance of gas access 55 to thorax chamber inlet 75 among the embodiment of Fig. 1) increases and increases.Δ v _GrainThen increase and particle density increase and reducing along with particle radius.If Δ v _GrainGreater than the optical fiber speed that enters, then entrainment has the particle of described given radius and density in the optical fiber boundary layer, will be stopped before arriving accumulator.Being preferably, is the particle more than 50 microns for the density with silicon dioxide, diameter, Δ v _GrainGreater than optical fiber speed.Be more preferably, for the density with silicon dioxide, bigger (as diameter more than 100 microns) particle, Δ v _GrainGreater than optical fiber speed.In a kind of more conservative method for designing, can make Δ v _JetOr ∑ Δ v _PipeGreater than optical fiber speed.

Fig. 5 is to be 50 microns silica dioxide granule for motion major diameter in the indoor constant speed carbon dioxide gas stream of thorax, and that calculates gained makes it stop the required distance and the relation of gas velocity.Ignored particle weight during calculating.It is 10m/s, 20m/s and 30m/s that curve A, B, C represent the particle starting velocity respectively.From figure, can know and find out that gas velocity has a significant impact the stop distance of particle.And, increase the difference of the stop distance between the particle that airflow rate can reduce to have different starting velocities greatly.For example, gas velocity (U _{Pipe max}) when being 3m/s, starting velocity is that the difference between the particle of 10m/s and the particle stop distance that initial velocity is 30m/s is approximately equal to 1.75 meters.And when gas velocity was 6m/s, the difference of this stop distance was decreased to less than 0.65 meter.The figure illustrates the ability that high velocity air stops particle with the very big starting velocity of variation range.

Determine the inside moving particle maximal rate Δ v that in Δ x, can stop _PipeEquation (8) and (9), can be used to estimate the degree of functioning of various thoraxes chamber minimum diameter and working fluid speed.For example, the flow rate Q of fluid is 6 liters of per minutes when requiring stop distance Δ x to be 2 centimetres, the working fluid air-flow that in the thorax chamber of 0.100 inch diameter, produces, and can make diameter is that the particle that 50 microns starting velocities are 22.9m/s stops.Therewith in pairs than, under similarity condition, same working fluid flow rate can only stop the particle that maximum starting velocity is 9.5m/s at the air-flow of 0.170 inch indoor generation of thorax.The thorax chamber that diameter is bigger, it stops ability will be lower.On the contrary, according to the device in the preferred embodiment of the present invention, can under given mass flowrate, around optical fiber, produce the air-flow of fair speed.Curve D among Fig. 6, E and F have shown that respectively the 6s/pm of carbon dioxide is 0.100 inch by diameter, and the theoretical velocity during the thorax chamber of 0.120 inch and 0.170 inch distributes.Can see that thus maximum thorax chamber diameter is about 0.100 inch device, be per minute 6 standards when rising in the flow rate of fluid, and the theoretical largest tube speed of generation is about 39m/s.

Another the tangible result who is obtained by equation (8) and (9) carries the Guan Liuqu of the thorax chamber of working fluid (entering the point of thorax chamber to the thorax chamber inlet from fluid) should be longer than the pairing Δ x of expection the largest particles that moves with optical fiber speed.

The minimum diameter of thorax chamber is little, except the jet that forms can increase the ability that stops particle, also because the target area reduces, and provides a kind of passive protection to entering of particle.For example diameter is 0.100 inch thorax chamber, and its target area only is 35% of 0.170 inch thorax chamber.

Thorax chamber inlet 75 is designed to produce maximum working fluid outgoing speed in this porch, supplies fiber optic collimator, particulate pollutants whole basically in typical wire drawing environment is got rid of outside the die clamp assembly and still leave enough clearances.Thorax chamber inlet of the present invention has been set up one the strong upwards jet that is sent by this inlet, thereby repels the particle that entrainment moves downward with optical fiber speed in the optical fiber boundary layer.

In contrast, former die clamp assembly does not design the working fluid that utilizes outgoing and enters die clamp to stop particle.For example, in a kind of existing die clamp, the thorax chamber diameter of Working-fluid intaking top is approximately 0.500 inch.The maximum functional fluid rate that this structure produces is lower, only is about 1.01m/s, and it is easy to be subjected to the interference of flow of ambient air in the wire drawing environment.This air-flow can only prevent that maximal rate from being the particle that moves downward of 1.45m/s.Particle so that typical fibre-optical drawing speed moves can not be repelled by this working fluid air-flow.

Other embodiment of said method and device is apparent to one skilled in the art.For example, thorax 53 can be stretched by another point away from the guiding mould, at guiding mould 51 and not between the end of guiding die clamper 50, has an optical fiber access hole (not shown) that thorax chamber 53 is connected with guiding nib 60 in this case.In addition, though thorax 53 is cylindrical uniformly on its whole length among Fig. 1, the present invention can use other shape.For example thorax 53 can have cone shape, the guiding mould end of the small end close control die clamper of taper.Also can use other the surfaces of revolution and pyramid.

The die clamp assembly needs regular cleaning to use microscopic examination then.The embodiment of Fig. 7 can be convenient to checkout procedure.Die clamp assembly 210 comprises that 220, one of a gluing die clamper that rubber moulding 221 wherein is housed wherein is equipped with the guiding die clamper 250 that guides mould 251, and die cover 270.The part of assembly 210 between the bottom surface of bottom surface 254 that guides die clamper 250 and last rubber moulding 221 is basic identical with the assembly among Fig. 1.

Guiding die clamper 250 is to be roughly columniform file, and the size of its outside surface 258 makes within its center bore 225 that can accurately be slidingly fitted in the gluing die clamper; When the guiding die clamper assembled up, its head 256 placed on the end face 235 of gluing die clamper.Thorax chamber 253 is extended to the end face of head 256 by guiding mould 251.Guiding die clamper 250 has an internal work fluid groove 254A on its outside surface 258, aim at the operate outside fluid bore 232 on the gluing die clamper 220.Hole 232 is communicated with the center bore 225 of groove 231 with gluing groove anchor clamps.Internal work fluid bore 255 is formed in the guiding die clamper, and 254A is communicated with thorax chamber 253 with internal work fluid groove.Similar to situation shown in Figure 2, guiding die clamper and gluing die clamper have when assembling up one rotary shifted, make operate outside fluid bore and the misalignment of internal work fluid bore.

Die cover 270 will guide the head 256 of die clamper 250 to be clipped between the end face 235 of the interior shoulder 272 of die cover and gluing die clamper 270.Die cover 270 comprises and is positioned at the projection 280 that the center is extended downwards vertically by shoulder 272.The lower end 282 of projection 280 is separated by a distance with the top of guiding mould 251, and this distance is enough to make working fluid to flow around it unfetteredly.One section zone 284 that diameter is narrower is arranged at the bottom of projection 280, aims at hole 255, allows working fluid be flowed into wherein by hole 255 so that an annular section 286 to be provided.

Die cover 270 has center pit 273, aims at guiding nib and gluing nib, makes whole these elements all coaxial with fiber axis 312.Lead-in chamfered 257 is arranged to help penetrating of optical fiber in the upper end in thorax hole 273.

Assembly 210 can decompose the cleaning die that comes.After finishing cleaning process, can check it by guiding mould 251 larger-diameter thorax holes 253 at an easy rate.Can be with the working fluid beyond the carbon dioxide, substitute carbon dioxide as nitrogen, V111 family or so-called your gas (as xenon, neon, argon etc.) and chemically inert carbon halogenide gas or its gas (as the hydro carbons that chloroform, fluorine Lyons carbon halide compound or other chlorine replace or fluorine replaces).In addition, the available hydraulic fluid compatible with coating material is as working fluid.Density of liquid is bigger, make it stop aspect the particle contamination more favourable.

The present invention below has been described in conjunction with specific embodiments, but should understand, these embodiment are the explanation of principle of the present invention and application, therefore can under the condition that does not deviate from spirit of the present invention and scope these illustrative embodiment be done various changes or make other arrangement.

Claims (15)

1. method that is coated with application layer on optical fiber comprises:

The optical fiber feeding is comprised in the accumulator of liquid coating, pass this accumulator and, make the coating that is stained with the described liquid of one deck on the optical fiber by the accumulator pass-out by its pass-out; And

Around the optical fiber that leads to accumulator, apply the air-flow or the liquid stream of working fluid, working fluid is flowed along optical fiber, its direction is opposite with the fibre movement direction, and it is measured maximal rate and is at least 1.5 meter per seconds at the adjacent fiber place, and this flowing process fluid will stop particle to enter accumulator.

2. the method for claim 1, the theoretical maximal rate that it is characterized in that described working fluid is to be selected from least 35 meter per seconds, at least 27 meter per seconds and at least 10 meters seconds.

3. the method for claim 1 is characterized in that, the described step that optical fiber is fed accumulator is to allow optical fiber pass the thorax chamber inlet enter the thorax chamber, again optical fiber is fed described accumulator by the thorax chamber, passes this accumulator then and passes to the optical fiber outlet; And the described step that applies working fluid comprises with working fluid described thorax chamber pressurization is made this working fluid leave accumulator and discharges by the thorax chamber inlet.

4. method as claimed in claim 3, the step that it is characterized in that described discharge fluid comprises: from the primary importance between accumulator and the thorax chamber inlet to the zone of thorax chamber inlet, at indoor air-flow or the liquid stream of keeping working fluid of thorax, its direction is opposite with the direction of fibre movement, and working fluid is at least 1.5 meter per seconds in the indoor theoretical largest tube speed of thorax.

5. method as claimed in claim 4 is characterized in that, described theoretical largest tube speed at thorax office work fluid is about 35 meter per seconds or about 27 meter per seconds.

6. method as claimed in claim 3 is characterized in that, the ventilation flow rate of described working fluid is to rise or about per minute 6 standard liters in per minute 10 standards.

7. method as claimed in claim 5 is characterized in that, described working fluid is 2.1 gram/cubic centimetres in density, and diameter is can make its largest particles speed that stops greater than the movement velocity of optical fiber to described accumulator before 50 microns particle arrives accumulator.

8. one kind in order to be coated with the device of application layer on optical fiber, comprising:

(a) die clamp, it has inlet end and endpiece;

(b) go up rubber moulding, it is in abutting connection with the endpiece of described die clamp, and rubber moulding is provided with a gluing nib on this;

(c) guiding mould, it is contained between the inlet end of rubber moulding and die clamp, this guiding mould is provided with a guiding nib, guiding nib and gluing nib are coaxial with fiber axis substantially each other, last rubber moulding, guiding mould and die clamp form an accumulator between last rubber moulding and guiding mould, in order to receiving fluids coating;

Limit around the device of the thorax chamber of fiber axis between guiding mould and die clamp inlet end, described thorax chamber is at the minimum diameter that has along a certain position of fiber axis less than 0.180 inch;

Between described guiding mould and above-mentioned position, be communicated in the workflow body opening of described thorax chamber;

Optical fiber can move through described thorax chamber and accumulator along fiber axis, and working fluid can feed the thorax chamber and leave the liquid accumulator in above-mentioned position around optical fiber and discharged by the thorax chamber.

9. device as claimed in claim 8 is characterized in that, described minimum diameter is about 0.100 inch or the diameter of littler and/or described thorax chamber on a segment length of at least 0.400 inch less than 0.200 inch.

10. device as claimed in claim 8 is characterized in that, described thorax chamber is limited by the hole of passing described die clamp at least in part.

11. device as claimed in claim 10 is characterized in that, described workflow body opening is to be limited by at least one hole in die clamp.

12. device as claimed in claim 10 is characterized in that, described die clamp also comprises a die cover at its inlet end, and described thorax chamber also is included in the hole in the described die cover.

13. device as claimed in claim 8 is characterized in that, described die cover also comprises the projection that extends to described guiding mould, and described thorax chamber is to be limited by the hole of passing this projection.

14. device as claimed in claim 13 is characterized in that, described projection in abutting connection with the diameter of the part of guiding mould less than the diameter of part of this projection away from the guiding mould.

15. device as claimed in claim 8, it is characterized in that, described die clamp comprise in order to the gluing die clamper of clamping rubber moulding, in order to clamp the guiding mould the guiding die clamper and described inlet end in order to connect above-mentioned gluing die clamper with the guiding die clamper die cover.

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