Valve device and resin coating apparatus incorporating same

An apparatus for coating an optical fibre with a selected one of a plurality of different resins includes respective reservoirs for the resins, an applicator for applying a resin coating to the optical fibre and a distributor between the reservoirs and the applicator including a valve device which is operable for putting any selected one of the reservoirs in flow communication with the applicator. The valve device includes a first body defining a plurality of inlet passages each of which is interconnected to a respective reservoir by a respective inlet conduit and a second body defining an outlet passage which is interconnected to the applicator via an outlet conduit. A flow control device is disposed between the bodies and the bodies are relatively moveable for putting any selected one of the inlet passages in alignment with the outlet passage. The flow control device has a first position relative to the second body for blocking all of the inlet passages and the outlet passage and a second position relative to the second body for allowing flow to the outlet passage from an inlet passage aligned therewith.

BACKGROUND OF THE INVENTION 
This invention relates to a valve device and more particularly, but not 
exclusively, to an apparatus for coating an elongate member with a 
selected one of a plurality of different resins, which apparatus 
incorporates a valve device. 
Optical fibres are coated with resin immediately after drawing from a 
preform to protect them from damage. Typically, such fibres are provided 
with two coatings, the first being a low modulus coating to buffer the 
fibre from lateral pressure and the second being a harder and more robust 
coating to protect the first coating, and hence the fibre, from mechanical 
damage. The coating is also advantageously used for identification 
purposes by being coloured. Colouring of the coating is conventionally 
achieved by `inking` it in a separate operation after its application, but 
this is disadvantageous as it adds an additional step to the manufacturing 
process. 
The use of a coloured resin for the visible coating (i.e. the second 
coating in the two coating arrangement discussed above) would eliminate 
the need for the `inking` step but presents its own problems. In 
particular, unless it were possible to dedicate separate fibre drawing 
lines to each colour, there is a need to clean the resin applicator each 
time it was required to change the colour of the visible coating. This 
requires not only labour but also causes a loss in production due to 
down-time and furthermore disruption of the applicator set-up. One 
solution to these problems is to provide the drawing line with a plurality 
of resin applicators each for applying a different coloured resin. 
However, this solution has the disadvantage of requiring a longer drawing 
line in order to accommodate the extra applicators and also the setting up 
of the extra applicators. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a valve device which 
enables different resins (e.g. different coloured resins) to be 
selectively supplied to an applicator for applying the resin to an 
elongate member (e.g. an optical fibre being drawn from a preform). 
The invention provides a valve device comprising a first body defining a 
plurality of inlet passages each of which is connectable to a respective 
inlet conduit; a second body defining an outlet passage connectable to an 
outlet conduit; and a flow control means disposed between said first and 
second bodies, said bodies being relatively moveable for putting any 
selected one of said inlet passages in alignment with said outlet passage, 
and said flow control means having a first position relative to said 
second body for blocking all of said inlet passages and said outlet 
passage and a second position relative to said second body for allowing 
flow to said outlet passage from an inlet passage aligned therewith. 
The invention also includes apparatus for coating an elongate member with a 
selected one of a plurality of different resins comprising a plurality of 
reservoirs for containing supplies of respective resins, an applicator for 
applying a resin coating to an elongate member and a distribution means 
between said reservoirs and said applicator comprising a valve device as 
defined in the last preceding paragraph, respective inlet conduits 
interconnecting said reservoirs with respective inlet passages of said 
valve device and an outlet conduit, via which said valve device is 
connected to said applicator. 
The above-mentioned valve bodies of the valve device are preferably 
relatively rotatable about an axis for putting any selected one of said 
inlet passages in alignment with said outlet passage, said inlet passages 
having ports adjacent said control means which are circumferentially 
spaced apart about said axis, said outlet passage having a port adjacent 
said control means with which port said inlet passage ports are alignable 
on relative rotation of said bodies. 
The control means may comprise a planar seal element disposed between 
respective faces of said bodies in which said ports are disposed for 
sealing engagement with said faces, said seal element having a 
through-aperture which is aligned with said outlet passage port in said 
second position of said flow control means and which is radially spaced 
from said outlet passage port in said first position of said flow control 
means. 
Selectively operable means may be provided for urging said body faces into 
engagement with said seal element. 
In a preferred embodiment, the second body is rotatable about said axis, 
and in this case advantageously said outlet passage extends within said 
second body from said port thereof adjacent said control means to a 
further port on said axis. 
In the above-mentioned preferred embodiment, the second body is supported 
for rotation about said axis adjacent said further port by a third body 
having a through passage aligned with said further port. 
Also in the preferred embodiment, the selectively operable means for urging 
said faces into engagement with said seal element comprises means for 
causing said third body to apply an axial force to said second body in a 
direction towards said first body.

DETAILED DESCRIPTION OF THE INVENTION 
Referring first to FIG. 1, the illustrated apparatus comprises a plurality 
of reservoirs, shown as 3 and referenced 10, 12 and 14 respectively. Each 
reservoir contains a supply of a different coloured resin 16, 18 and 20. 
Conduits 22, 24 and 26 interconnect the reservoirs 10, 12, 14 with 
respective inlet passages 28, 30 and 32 of a valve device 34. The valve 
device has a single outlet passage 36 which is connected via an outlet 
conduit 38 to an applicator 40 for applying a resin coating to an optical 
fibre 42 which is being drawn from a preform (not shown). 
The inlet passages 28, 30 and 32 are defined in a first body 44 of the 
valve device and the outlet passage 36 is defined in a second body 46 of 
the valve device. The valve device also comprises a flow control means 48 
disposed between bodies 44 and 46. The flow control means has a first 
position relative to the body 46 for blocking all of the inlet passages 
28, 30, 32 and also the outlet passage 36 and a second position relative 
to the second body for allowing flow to the outlet passage 36 from an 
inlet passage aligned therewith. As schematically illustrated, the flow 
control means is in its second position allowing flow to the outlet 
passage 36 from the aligned inlet passage 28 through a through-aperture 
50. 
The reservoirs 10, 12, 14 are pressurised in order to direct flow towards 
the valve device. Thus, in the illustrated condition of the valve device, 
resin 16 from reservoir 10 is being directed through conduit 22, inlet 
passage 28, through-aperture 50, outlet passage 36 and outlet conduit 38 
to the applicator 40. Resins 18 and 20 from the other two reservoirs 12 
and 14 are being directed through conduits 24 and 26 to inlet passages 30 
and 32, but flow from the inlet passages 30 and 32 is blocked by the flow 
control means 48. 
When it is desired to coat the optical fibre with resin 18 or 20 instead of 
resin 16, the flow control means is put into the above-mentioned first 
position in which all of the inlet passages 28, 30 and 32 are blocked, 
whereupon the bodies 44 and 46 are relatively moved to put inlet passage 
30 or inlet passage 32 into alignment with outlet passage 36 and 
thereafter the control means is put into its second position for allowing 
flow from inlet passage 30 or 32 to outlet passage 36 through 
through-aperture 50. In the first position of the flow control means the 
outlet passage 36 is also blocked thereby in order to prevent backflow of 
resin from the outlet passage 36. 
In the illustrated apparatus, the second body 46 is rotated relative to the 
first body 44 to put the outlet passage in alignment with a selected inlet 
passage. In this case, the flow control means is arranged to rotate with 
the valve body 46 and is moveable between the above-mentioned first and 
second positions by a sliding movement transverse the axis about which it 
and the body 46 rotates. 
A preferred embodiment of the valve device 34, which is only schematically 
illustrated in FIG. 1, will now be described with reference to FIGS. 2 to 
6. In these figures the parts of the valve device described above are 
given like reference numerals where appropriate. Whilst the valve device 
34 in FIG. 1 is illustrated as having only three inlet passages in the 
first body 44, the preferred embodiment is provided with seven such inlet 
passages (as best appreciated from FIGS. 5 and 6) and for the sake of 
clarity, each of these inlet passages has been referenced 28. It will be 
understood, of course, that any number of inlet passages may be provided. 
The valve device of FIGS. 2-6 comprises the above-mentioned first and 
second bodies 44, 46, the control means 48 and a third body 52 assembled 
together and mounted on a mount comprising a base 54, a first end wall 56 
mounted to the base 54 at one end thereof and upstanding from the base, a 
second end wall 58 mounted to the other end of the base 54 and upstanding 
therefrom and a tie rod 60 interconnecting the end walls 56 and 58 at 
portions thereof remote from the base 54. 
The end wall 56 is bifurcated, with two arms 62 extending from a base 
portion 64 as best shown in FIG. 3. The end wall 58 is generally 
triangular in shape as shown in FIG. 4. The tie rod 60 extends through a 
slot 66 in the end wall 58 and a bore 68 in a crosspiece 70 extending 
between the arms 62 of the end wall 56. The tie rod is threadedly engaged 
with the bore 68 and is tensioned by means of a nut 72 which threadedly 
engages the opposite end of the tie rod. 
The first body 44 of the valve device is mounted adjacent the end wall 56 
and in overlapping relationship therewith on a support foot 74 on the base 
54. The body 44 which is otherwise generally cylindrical is provided with 
stepped recesses in order to allow its overlapping relationship with end 
wall 56. As best shown in FIG. 6, these recesses define a flat side 
surface 76 for engagement with the axially inwardly facing side surface of 
the base portion 64 of the wall 56 and respective flat side surfaces 78 
for engaging the axially inwardly facing side surfaces of the arms 62 of 
the wall 56. The body 44 is secured against rotation relative to the mount 
by bolt 80 which passes through support foot 74 and is threadedly engaged 
with the body 44 and additionally by virtue of its overlapping 
relationship with the end wall 56. 
The second body 46 is mounted for rotation relative to the first body 44 
about an axis 82. To this end a pivot 84 on the axis extends into 
respective bores 86 and 88 of the two bodies. Rotational support at the 
end of the second body 46 remote from the first body 44 is achieved using 
the third body 52 which is provided with an annular, radially inwardly 
facing bearing surface 90 which cooperates with a radially outwardly 
facing annular bearing surface 92 provided on the second body 46. 
The inlet passages 28 are circumferentially spaced apart about the axis 82 
and ports 94 thereof also circumferentially spaced apart about axis 82 are 
disposed in a planar face 96 of the first body 44 adjacent the control 
means 48. The outlet passage 36 in the second body 46 has a port 98 in a 
planar surface 100 adjacent the control means 48 and positioned such that 
the port 98 is alignable with any selected one of the ports 94 on rotation 
of the body 46 about the axis 82 relative to the body 44. 
The outlet passage 36 extends within the second body from the port 98 to a 
further port 102 on the axis 82 at the end of the second body 46 supported 
by the third body 52. The third body has a through-passage 104 on the axis 
82 which is therefore always in flow communication with the port 102. 
The flow control means 48 comprises a seal element formed as a plate 106 
held within a holder 108. The seal plate 106 which advantageously may be 
formed from a PTFE material is disposed between the body 44 and the body 
46 and is provided with a slot 109 through which the pivot 84 extends to 
allow sliding movement of the seal plate transverse the axis 82. Such 
sliding movement is controlled by two slide bars 110 (one only shown in 
the figures) which extend through through-bores 111 through the second 
body 46, one on each side of the axis 82, between an operating handle 112 
and a stop member 114, each of which is secured to the holder 108. The 
flow control means and the second body 46 rotate together about axis 82 by 
virtue of the slide bars 110 of the former extending through the 
through-bores 111 of the latter. 
The through-aperture 50 of the control means is provided in the seal plate 
106 in radial alignment with the slot 109. In the figures, the flow 
control means is illustrated in the above-mentioned first position--the 
seal plate 106 blocking all of the inlet passages and the outlet passage. 
It will be appreciated that by sliding the flow control means downwardly 
(as viewed in the figures) the through-aperture 50 will be moved into 
alignment with the port 94 of the inlet passage 28 shown in FIG. 2 and the 
port 98 of the outlet passage 36 allowing flow between those passages. It 
will also be understood that in this position the seal plate blocks flow 
from the ports 94 of the other inlet passages. The holder 108 also carries 
a location pin 116, which locates within one of a plurality of radial 
bores 118 in the first body 44 when the port 94 of an inlet passage 
associated with that bore is aligned with the port 98. 
The third body 52 is supported on the base 54 by a support foot 120 which 
is secured to the third body by a bolt 122 but is free to slide on the 
base 54. The third body is provided with a threaded portion 124 which 
extends through a bore 126 in the end wall 58. A nut 128 is threadedly 
engaged with the threaded portion 124 and located axially inward of the 
end wall 58. Movement of the nut in the axially outward direction causes 
it to engage the axially inward facing surface 130 of the end wall 58 
whereupon further movement in that direction urges the third body 52 
towards the second body to compress a seal plate 132 therebetween and to 
cause the second body 46 to be urged towards the first body 44, thus 
urging the respective faces 96 and 100 of the first and second bodies into 
engagement with the seal plate 106. To assist fine rotation of the nut 
128, it is provided with a radially outwardly extending lever arm 134. 
It will be appreciated that the nut 128 is screwed into engagement with the 
surface 130 of the end wall to urge the third and second bodies into 
sealing engagement with the seal 132 and the second and first bodies into 
sealing engagement with the seal plate 106 when the latter is in its 
second position allowing flow to the outlet passage 36 from a selected one 
of the inlet passages 28 which has been aligned therewith. 
In order to align the outlet passage 36 with a different inlet passage 28, 
for example when it is desired to change the colour of the resin being 
applied to an optical fibre, the nut is slackened off sufficiently to 
enable the flow control means 48 to be slid to its first position (as 
illustrated in the figures) and to allow rotation of the second body 46 
together with the control means 48 about the axis 82 to bring the new 
inlet passage 28 into alignment with the outlet passage. During this 
sliding and rotating movement of the control means, the seal plate is 
still effective to block flow from the inlet passages, each of which 
contains resin under pressure from the respective reservoirs, and also to 
prevent backflow of resin from the outlet passage 36. To assist this 
alignment operation, a collar 136 is mounted for rotation with the second 
body 46 and is provided with circumferentially spaced apart marks which 
align with a mark on a ring 138 secured to the third body adjacent thereto 
when the inlet passages are aligned with the outlet passage. When such an 
alignment occurs, the control means is slid to its second position, the 
pin 116 being received in the bore 118 associated with the selected index 
passage. Thereafter the nut is re-tightened to increase the effectiveness 
of the seals between the third and second and the second and first bodies. 
The illustrated valve device enables a colour change for the resin being 
applied to an optical fibre to be achieved relatively quickly. The valve 
is self-flushing with the old colour resin being removed by the new colour 
resin. The speed at which a change of colour may be achieved can be 
increased by providing the applicator with a bleed valve 140 as 
illustrated in FIG. 1. As will be appreciated, the bleed valve would be 
opened until the colour of the resin reaching the applicator was as 
required. In this connection it will also be appreciated that in the 
illustrated valve device there is no dead-space in which the old colour 
might remain thereby contaminating the new colour. 
It will also be understood that as the reservoirs remain pressurised at all 
times and the ports 94 and 98 are blocked during a changeover, the risk of 
air being introduced into the resin being applied is minimised. 
It will also be understood that there is no need to disturb the set-up of 
the applicator during a colour change.