Field of the Invention
[0001] The present invention relates to a melt spinning apparatus, and more specifically,
to a melt spinning apparatus that can execute spinning so as to obtain notably a very
fine multifilament yarn that is uniform and that has an even fineness.
Background of the Invention
[0002] In general, for melt spinning of a thermoplastic polymer, a molten polymer is supplied
by an extruder to spinning packs and spun out of a spinneret of the spinning packs
as filaments. Cooling winds are then blown against the filaments to solidify them
to obtain a multifilament yarn. However, the more filaments are spun out, the more
difficult it is to uniformly cool each of the filaments in a longitudinal direction.
Then, the cooling may be uneven, the filaments may come into contact with each other
below the spinneret, or the fineness may be uneven.
[0003] In particular, for very fine filaments of single filament size at most 0.55 dtex
or even at most 0.33 dtex, each filament is likely to have a high internal strain
and to be affected by associated air currents or cooling winds, resulting in an uneven
fineness. Further, owing to the very fine single filament fineness, the number of
filaments constituting the multifilament yarn is twice to five times as large as that
of filaments constituting a common yarn. Consequently, the above tendency is more
prone to occur.
[0004] A known effective method for uniformly cooling melt spinning filaments comprises
arranging cylindrical spin cooling cylinders below respective spinning packs and blowing
cooling winds into the spin cooling cylinders from their top portions so that the
winds flow parallel with the filaments (for example, International Publication No.
WO 99/067450A). It is known that if the spin cooling cylinders are thus used for cooling,
a certain method can be very effectively used to make the cooling action more uniform
particularly if very fine filaments are subjected to melt spinning. This method comprises
using packing to seal the upper end of each of the spin cooling cylinders from the
corresponding spinning pack so that cooling winds from the spin cooling cylinder will
not flow in the adjacent pack, as described in the International Publication No.WO
01/79594A.
[0005] However, if the seal is formed by abutting the upper end of each spin cooling cylinder
directly against the corresponding spinning pack as described in International Publication
No. WO 01/79594A, it is disadvantageously difficult to form a perfect seal for the
reason below. Thus, external cooling winds may flow into the spin cooling cylinder
through the imperfect seal to disturb the original cooling winds. As a result, the
filaments are disadvantageously not uniformly cooled.
[0006] Specifically, each spinning pack is constructed by assembling a plurality of parts
together, so that when the spinning packs are installed, the positions of their lower
ends vary unavoidably because of errors in the manufacture of these parts or a variation
in the amount of collapse of seal elements during assembly and mounting, the seal
elements belonging to the spinning packs.
[0007] Consequently, it is difficult to make the lower ends of all the spinning packs flush
with one another. Thus, the seal portion at the upper end of each spin cooling cylinder
may be imperfect. Further, cooling winds from the adjacent spin cooling cylinder may
flow in to cause uneven cooling. This effect is likely to be produced particularly
if the cooling section is provided with an integral cooling wind supply box that cover
the plurality of spinning packs and if the filament spinning cylinders are provided
inside the cooling wind supply box in association with the respective spinning packs.
[0008] It is an object of the present invention to provide a melt spinning apparatus that
can execute spinning so as to obtain a uniform multifilament yarn having an even fineness.
[0009] It is another object of the present invention to provide a melt spinning apparatus
that can execute melt spinning so as to obtain a very fine multifilament yarn which
is composed of uniform filaments and which is uniform in a longitudinal direction
particularly even if the very fine multifilament yarn has a single filament fineness
of at most 0.55 dtex.
Summary of the Invention
[0010] To accomplish these objects, the present invention provides a melt spinning apparatus
comprising a plurality of spinning packs installed in a pack housing contained in
a spinning beam, the spinning packs being arranged in a line, an integral Quenching
stack provided below the plurality of spinning packs so as to be shared by the spinning
packs, and filament cooling cylinders each comprising a cylindrical filter and provided
inside the Quenching stack in association with the respective spinning packs, the
apparatus being characterized in that a first seal mechanism is used to seal a top
portion and a bottom portion of each of the filament cooling cylinders from a top
plate and a bottom plate, respectively, of the Quenching stack, and a second seal
mechanism is used to seal the top portion of the filament cooling cylinder from a
bottom surface of the pack housing via a spacer.
[0011] Thus, the first seal mechanism is used to seal the top portion and bottom portion
of each of the filament cooling cylinders from the top plate and bottom plate, respectively,
of the Quenching stack, and the second seal mechanism is used to seal the top portion
of the filament cooling cylinder from the bottom surface of the pack housing via the
spacer. Accordingly, it is possible to allow only stable cooling winds having passed
through the filament cooling cylinders to flow into uniformly cool spun-out filaments.
Further, since the second seal mechanism is used to seal the top portion of the filament
cooling cylinder from the bottom surface of the pack housing, not from the spinning
pack, the spun-out filaments can be reliably uniformly cooled without any seal leakage
even if the mounting heights of the spinning packs are changed as a result of the
replacement of the packs.
Brief Description of the Drawings
[0012]
Figure 1 is a schematic sectional view showing an embodiment of a melt spinning apparatus
according to the present invention.
Figure 2 is an enlarged view of a part of Figure 1 shown by an arrow P.
Figure 3 is a partly exploded top view taken along a line III-III in Figure 1.
Figure 4 is a top view corresponding to Figure 3 according to another embodiment of
the present invention.
Figure 5 is a schematic perspective view of a filaments cooling cylinder in the melt
spinning apparatus according to the present invention.
Figure 6 is a schematic view illustrating a porous plate used for a cooling wind supply
path in the melt spinning apparatus according to the present invention.
Figure 7 is a schematic sectional view showing essential parts of another embodiment
of the present invention.
Figure 8 is a schematic sectional view showing essential parts of yet another embodiment
of the present invention.
Figure 9 is a schematic sectional view showing essential parts of further another
embodiment of the present invention.
Detailed Description of the Preferred Embodiments
[0013] A thermoplastic polymer applied to a melt spinning apparatus according to the present
invention is not particularly limited. Any thermoplastic polymer is available for
the melt spinning apparatus provided that it can be used to form fibers. The thermoplastic
polymer includes, for example, polyamide, polyester, or polyolefin.
[0014] The melt spinning apparatus according to the present invention can execute spinning
so as to obtain a uniform multifilament yarn regardless of the single filament fineness
of spun-out filaments. However, the melt spinning apparatus is particularly effective
on the melt spinning of a multifilament yarn of single filament fineness at most 0.55
dtex or even at most 0.33 dtex. Moreover, the melt spinning apparatus is very effective
on the melt spinning of a very fine multifilament yarn having such a small filament
yarn fineness and containing at least 90 filaments in total.
[0015] The melt spinning apparatus according to the present invention will be described
below in detail with reference to the specific embodiment shown in the drawings.
[0016] In Figures 1 to 3, a pack housing 33 is provided in an upper spinning beam 1. A plurality
of spinning packs 2 are housed inside the pack housing 33 so as to be arranged in
a direction orthogonal to the sheet of the drawing. A spinneret 3 is incorporated
into each of the spinning packs 2 and has an exposed bottom surface. A plurality of
pack housings 33 may be formed for the respective spinning packs 2 or an integral
pack housing 33 may comprise a plurality of installation holes in which the respective
spinning packs can be installed.
[0017] A filament cooling device 6 is provided below the spinning packs 2 installed in the
pack housing 33 as described above. The filament cooling device 6 blows cooling winds
against filaments Y constituting the multifilament yarn at 20 to 50 mm below a bottom
surface of each of the spinnerets 3. The filament cooling device 6 has independent
filament cooling cylinders 44 for the respective spinning packs 2 so that each of
the cooling cylinders 44 surrounds the filaments Y spun out of the spinning pack 2
through the spinneret 3. The filament cooling cylinders 44 are installed in a cooling
wind supply box 15. The cooling wind supply box 15 is integrally formed so as to be
shared by the plurality of spinning packs 2. The independent filament cooling cylinders
44 are provided inside the outer cooling wind supply box 15 for the respective spinning
packs 2 (see Figure 3). In the illustrated example, each of the filament cooling cylinders
44 has a double structure composed of an inner cylindrical filter 8 and an outer cylindrical
filter 9, as shown Figure 5.
[0018] In the filament cooling device 6, a heat insulating member 24 composed of an adiabatic
material is provided between a top plate 6b of the cooling wind supply box 15 and
a bottom surface of the pack housing 33 so as to surround the installation holes in
the spinning packs 2. The heat insulating member 24 maintains a bottom surface of
each of the spinnerets 3 at an appropriate temperature for melt spinning. Further,
a protective cover 12 for the filament Y is separably connected to a bottom surface
of each filament cooling cylinder 44. An oiling device 11 is provided in a lower part
of the protective cover 12 so as to apply a lubricant to the filaments Y cooled by
cooling winds through the filament cooling cylinder 44. Moreover, a winding device
is provided downstream of the oiling device 11 via a godet roller for drawing the
filaments Y (not shown in the drawings).
[0019] In the filament cooling device 6, pieces of packing 21, 22 are provided as a first
seal mechanism, a piece of packing 21 is provided between a top surface of each filament
cooling cylinder 44 and a top plate 6b of the cooling wind supply box 15, and a piece
of packing 22 is provided between a bottom surface of each filament cooling cylinder
44 and a bottom plate 6c of the cooling wind supply box 15. The filament cooling cylinder
44 is thus sealed from the top plate 6b and bottom plate 6c of the cooling wind supply
box 15. The first seal mechanism forms a seal to prevent the flow, into a filament
path 27, of the cooling winds other than those passing through the cylindrical filters
8, 9 of the filament cooling cylinder 44.
[0020] Furthermore, a seal plate 5 as a spacer is placed on the top plate 6b of the cooling
wind supply box 15 via packing 39. The seal plate 5 partly overlaps the packing 21
at the top of the filament cooling cylinder 44 and has its top surface sealed from
the bottom surface of the pack housing 33 using packing 20 as a second seal mechanism.
The second seal mechanism forms a seal to hinder external cooling winds from flowing
into the filament path extending from the top portion of the filament cooling cylinder
44 to the bottom surface of the pack housing 33. This prevents the disturbance of
the filament Y passing through a downstream side of the filament cooling cylinder
44. Further, the top portion of the filament cooling cylinder 44 is sealed from the
bottom surface of the pack housing 33, not from the corresponding spinning pack 2.
Accordingly, even if the mounting height of the spinning pack 2 is changed as a result
of, for example, the replacement of the spinning pack, it is possible to prevent the
seal leakage between the top portion of the filament cooling cylinder 44 and the bottom
surface of the pack housing 33.
[0021] The seal plate 5, inserted as a spacer as described above, has its thickness varied
to set the appropriate distance from the bottom surface of each spinneret 3 to a cooling
wind blowout start position of the filament cooling cylinder 44. The distance from
the bottom surface of each spinneret 3 to the cooling wind blowout start position
of the filament cooling cylinder 44 is not particularly limited but is preferably
selected in accordance with the single filament fineness. This distance is preferably
between 20 and 50 mm, more preferably between 30 and 40 mm for the spinning of a very
fine filament.
[0022] The illustrated filament cooling device 6 has an elevating and lowering device 13
provided on a rear surface of the protective cover 12 and driven by a hydraulic cylinder.
The elevating and lowering device 13 enables the filament cooling device 6 to be elevated
and lowered via the protective cover 12. After the filament cooling device 6 has been
lowered, the spinning packs 2 can be replaced with new ones or the spinnerets 3 can
be cleaned. Further, since the filament cooling device 6 can be elevated and lowered
for all of the plurality of spinning packs 2, the airtight sealing characteristic
of the yarn cooling device 6 is further enhanced.
[0023] The cooling wind supply box 15 of the filament cooling device 6 is connected to a
cooling wind supply duct 26 via a duct 32. A porous piece 7 such as the one shown
in Figure 6 is incorporated into the connection between the cooling wind supply duct
26 and the duct 32. The porous piece 7 serves to make the air flow of cooling winds
and their static pressure uniform to allow the cooling winds to be uniformly distributed
to the filament cooling cylinders 44 in the cooling wind supply box 15 (see Figure
3). The porous piece 7 preferably has an open area ratio of 30 to 50% and is composed
of a material having a transmission resistant characteristic or a combination of the
material. For example, the material is a wire mesh, a non-woven cloth, or a porous
plate such as a corrosion-resistance metal and plastics.
[0024] An air flow regulating device 14 and an expansion joint 17 are incorporated into
the cooling wind supply duct 26. The air flow regulating device 14 properly adjusts
the air flow to the filament cooling device 6. The expansion joint 17 allows the elevating
and lowering device 13 to smoothly perform operations of elevating and lowering the
filament cooling device 6.
[0025] In the integral cooling wind supply box 15 of the filament cooling device 6, which
covers the plurality of spinning packs 2, the plurality of filament cooling cylinders
44 may be arranged in a line as shown in Figure 3. Alternatively, the filament cooling
cylinders 44 may be staggered as shown in Figure 4 in association with the staggered
arrangement of the spinning packs 2 (spinnerets 3) with respect to the spinning beam
1. The staggered arrangement makes the melt spinning apparatus compact.
[0026] The number of filament cooling cylinders 44 in the integral cooling wind supply box
15 can be arbitrarily set and may be, for example, 4, 6, 8, 10, 12, 14, 16. For the
inner cylindrical filter 8 and the outer cylindrical filter 9, constituting the filament
cooling cylinder 44, the outer cylindrical filter 9 may be formed of a porous plate
of open area ratio 5 to 8%, while the inner cylindrical filter 8 may be formed of
a porous filter having a lower open area ratio than the outer cylindrical filter 9.
The cylindrical filters 8, 9, constituting the filament cooling cylinder 44, are preferably
set to have a cooling wind blowout length of 80 to 100 mm when incorporated into the
cooling wind supply box 15.
[0027] When the pressure loss in the filament cooling cylinder 44, having such a double
structure, is defined as ΔP (kPa) and the flow rate of cooling winds per unit area
is defined as Q (litter/min/cm
2), the filament cooling cylinder 44 is preferably set to have a passing resistance
ΔP/Q of 0.02 to 0.06. To accomplish this passing resistance, a wire mesh or a non-woven
cloth may be incorporate between the inner cylindrical filter 8 and the outer cyrindrical
filter 9. When the passing resistance ΔP/Q is lower than 0.02, the static pressure
and the air flow of cooling winds may not be uniform among the filament cooling cylinders
44 and within each filament cooling cylinder 44. Then, it is difficult to uniformly
cool the filaments. On the other hand, if the passing resistance ΔP/Q is higher than
0.06, the pressure loss in the filament cooling cylinder 44 increses. Consequently,
an insufficient air flow is blown into the filament cooling cylinder 44, thus hindering
uniform cooling. If an attempt is made to blow a sufficient air flow of cooling winds
into the filament cooling cylinder 44 while the pressure loss remains heavy, running
costs may increase. This is economically disadvantageous.
[0028] Figure 7 shows essential parts of another embodiment of a melt spinning apparatus
according to the present invention.
[0029] As in the case of the embodiment shown in Figures 1 and 2, previously described,
the seal plate 5 is placed on the packing 21 at the top of the filament cooling cylinder
44, with the packing 20 placed on the top surface of the seal plate 5. The present
embodiment differs from the above embodiment in that the packing 20 is not allowed
to adhere directly to the bottom surface of the pack housing 33 but in that a firm
seal is formed by using a seal ring 35 having an annular projecting portion 35a which
projects downward and which cuts into the surface of the packing 20. The seal ring
35 also acts as a spacer. The seal ring 35 is formed on the bottom surface of the
pack housing 33 so as to surround the installation hole in the spinning pack 2. The
seal ring 35 is removably screwed into the bottom surface of the pack housing 33.
The projecting portion 35a can be allowed to cut into the surface of the packing 20
by using the elevating and lowering device 13 to raise the protective cover 12.
[0030] Figure 8 shows essential parts of another embodiment of a melt spinning apparatus
according to the present invention.
[0031] In the embodiment shown in Figure 8, the seal ring 35, having the annular projecting
portion 35a projecting downward, is removably screwed into the bottom surface of the
pack housing 33 as in the case of Figure 7. The seal ring 35 acts as a spacer. Further,
the seal plate 5, placed on the packing 21 at the top of the filament cooling cylinder
44 in Figure 7, is replaced with an annular pot 37 in the embodiment shown in Figure
8. The pot 37 is filled with a fluid metal 43 acting as a seal material. Then, a seal
is formed by immersing the annular projecting portion 35a of the seal ring 35 into
the liquid metal 43.
[0032] The applicable liquid metal include a low-temperature solder, a fuse, or a low-melting-point
material used in a fire hydrant, a high pressure reservoir safety plug, a dental material,
a physical or chemical model, or the like.
[0033] Also in the present embodiment, the annular projecting portion 35a of the seal ring
35 can be immersed into the liquid metal 43 by using the elevating and lowering apparatus
13 to raise the protective cover 12.
[0034] Figure 9 shows essential parts of another embodiment of a melt spinning apparatus
according to the present invention.
[0035] In the embodiment shown in Figure 9, the spinning pack 2 is installed so that its
bottom portion projects below the bottom surface of the pack housing 33. Since the
bottom portion of the spinning pack 2 thus projects downward, a heater 4 is set around
the projecting portion so as to maintain the surface temperature of the spinneret
3 at a predetermined value (spinning temperature≧ the predetermined value≧spinning
temperature-10°C). The heater 4 is fixed to the bottom surface of the pack housing
33 via adiabatic packing 19. The packing 20 and seal ring 5, which are similar to
those in the embodiment shown in Figures 1 and 2, are abutted against the bottom surface
of the heater 4.
[Example]
[0036] The melt spinning apparatus shown in Figures 1 and 2 was used to subject polyethylene
terephthalate to melt spinning while taking it off at a drawing speed of 2,800 m/min.
Thus, a partly oriented non-drawn multifilament yarn of 82 dtex was obtained which
was composed of 177 very thin filaments.
[0037] An Uster yarn unevenness measuring instrument manufactured by Zellweger Uster AG
was used to measure the non-drawn multifilament yarn obtained for Uster unevenness
U (%) under normal conditions. The measured value was 0.7%. Under a half inert condition,
the Uster unevenness U was 0.3%. Both measured values were very small, indicating
that the multifilament yarn obtained was uniform.
[0038] The partly oriented non-drawn multifilament yarn was textured by simultaneously drawing
and false twisting. The yarn obtained was free from dying unevenness and was favorable
in texturing.
[0039] As described above in detail, according to the melt spinning apparatus according
to the present invention, the first seal mechanism is used to seal the top portion
and bottom portion of each of the filament cooling cylinders from the top plate and
bottom plate, respectively, of the integral cooling wind supply box, and the second
seal mechanism is used to seal the top portion of the filament cooling cylinder from
the bottom surface of the pack housing. Consequently, it is possible to allow only
stable cooling winds having passed through the filament cooling cylinders to flow
in to uniformly cool spun-out multifilaments. Further, since the second seal mechanism
is used to seal the top portion of each filament cooling cylinder from the bottom
surface of the pack housing, not from the spinning pack, the spun-out multifilaments
can be reliably uniformly cooled without any seal leakage even if the mounting heights
of the spinning packs are changed as a result of the replacement of the packs.
1. A melt spinning apparatus comprising a plurality of spinning packs installed in a
pack housing contained in a spinning beam, the spinning packs being arranged in a
line, an integral cooling wind supply box provided below said plurality of spinning
packs so as to be shared by the spinning packs, and filament cooling cylinders each
comprising a cylindrical filter and provided inside the cooling wind supply box in
association with said respective spinning packs, the apparatus being
characterized in that:
a first seal mechanism is used to seal a top portion and a bottom portion of each
of said filament cooling cylinders from a top plate and a bottom plate, respectively,
of said cooling wind supply box, and a second seal mechanism is used to seal the top
portion of the filament cooling cylinder from a bottom surface of said pack housing
via a spacer.
2. A melt spinning apparatus according to Claim 1, characterized in that said spinning packs are arranged in a line in a staggered manner.
3. A melt spinning apparatus according to Claim 1, characterized in that said cylindrical filter comprises at least one of a porous plate, a wire mesh, a
non-woven cloth, and a porous material.
4. A melt spinning apparatus according to Claim 3, characterized in that when a pressure loss of said filament cooling cylinder is defined as ΔP (kPa) and
the flow rate of cooling winds per unit area is defined as Q (litter/min/cm2), a passing resistance ΔP/Q is set to be between 0.02 and 0.06.
5. A melt spinning apparatus according to any one of claims 1 to 4, characterized in that said second seal mechanism comprises a seal ring formed with an annular projecting
portion projecting downward, and a ring-like packing, and the annular projecting portion
of said seal ring is pressed against said packing.
6. A melt spinning apparatus according to any one of Claims 1 to 4, characterized in that said second seal mechanism comprises a seal ring formed with an annular projecting
portion projecting downward, and a ring-like pot filled with a liquid metal, and the
annular projecting portion of said seal ring is immersed into said liquid metal.
7. A melt spinning apparatus according to any one of Claims 1 to 6, characterized in that an annular heat insulating member is placed between said pack housing and said cooling
spinning cylinders.
8. A melt spinning apparatus according to any one of Claims 1 to 7, characterized in that the apparatus is used for melt spinning of a very thin multifilament yarn of single
filament size at most 0.55 dtex.