SPINNERET ASSEMBLY FOR MULTICOMPONENT FIBERS
United States Patent 3601846
A spinneret assembly for providing multicomponent fibers with intimate contact along their length, and including three separately formed plates positioned in contiguous, coextensive alignment, and having separate feed inlets for two or more separate spinnable mediums with a separate flow path for each spinnable medium, the separate flow paths coming together within a counterbore recess in the downstream surface of the second plate for subsequent conjoint flow of the spinnable mediums from the second plate and through the third plate.
US Patent References:
/2923970.html
Genovese - February 1960 - 2923970
Composite filament
Tanner - January 1964 - 3117906
Apparatus for producing composite filaments
Hollandsworth - May 1967 - 3316589
Apparatus for forming two component yarns
Cancio et al. - May 1967 - 3320633
MELT EXTRUSION PROCESS AND SPINNERETTES
Grenier - April 1970 - 3507947
/2923970.html
Genovese - February 1960 - 2923970
Composite filament
Tanner - January 1964 - 3117906
Apparatus for producing composite filaments
Hollandsworth - May 1967 - 3316589
Apparatus for forming two component yarns
Cancio et al. - May 1967 - 3320633
MELT EXTRUSION PROCESS AND SPINNERETTES
Grenier - April 1970 - 3507947
Application Number:
05/005501
Publication Date:
08/31/1971
Filing Date:
01/26/1970
View Patent Images:
Export Citation:
Assignee:
Eastman Kodak Company (Rochester, NY)
Primary Class:
Other Classes:
425/382.200, 425/DIG.217, 264/172.140, 425/198, 425/199
International Classes:
D01D5/32; D01D5/30; D01D3/00
Field of Search:
18/8 264/76F,76R
Primary Examiner:
Overholser, Spencer J.
Assistant Examiner:
Sutton, Michael O.
Claims:
I claim
1. A spinneret assembly for producing multicomponent fibers with intimate contact along their length, and comprising three plates disposed in contiguous, coextensive alignment,
2. A spinneret assembly as defined in claim 1 and wherein the first plate defines therethrough from each feed inlet two feed passages, each of the two feed passages opening into the annular channel at a location opposed to the other feed passage opening into the channel.
3. A spinneret assembly as defined in claim 1, and wherein the second plate defines therethrough feed passages each extending from one of the annular channels, with one feed passage from each annular channel meeting in one of the counterbore recesses in the second plate.
4. A spinneret assembly as defined in claim 1, and wherein the counterbore recess in the second plate is cone-shaped in configuration, and the counterbore recess in the third plate is hemispherical-shaped in configuration.
5. A spinneret assembly as defined in claim 1, and wherein each feed passage in the second plate has a predetermined length and diameter that is correlated to the size of the flow path defined in the related annular channel so that the maximum pressure drop through the feed passages related to such annular channel is greater than the maximum pressure drop encountered in the flow of a spinnable medium around such annular channel by a factor of 10 or more.
1. A spinneret assembly for producing multicomponent fibers with intimate contact along their length, and comprising three plates disposed in contiguous, coextensive alignment,
2. A spinneret assembly as defined in claim 1 and wherein the first plate defines therethrough from each feed inlet two feed passages, each of the two feed passages opening into the annular channel at a location opposed to the other feed passage opening into the channel.
3. A spinneret assembly as defined in claim 1, and wherein the second plate defines therethrough feed passages each extending from one of the annular channels, with one feed passage from each annular channel meeting in one of the counterbore recesses in the second plate.
4. A spinneret assembly as defined in claim 1, and wherein the counterbore recess in the second plate is cone-shaped in configuration, and the counterbore recess in the third plate is hemispherical-shaped in configuration.
5. A spinneret assembly as defined in claim 1, and wherein each feed passage in the second plate has a predetermined length and diameter that is correlated to the size of the flow path defined in the related annular channel so that the maximum pressure drop through the feed passages related to such annular channel is greater than the maximum pressure drop encountered in the flow of a spinnable medium around such annular channel by a factor of 10 or more.
Description:
BACKGROUND OF THE INVENTION
The present invention relates to a spinneret assembly for producing multicomponent fibers, and particularly a spinneret assembly for producing multicomponent fibers of the side-by-side type.
Multicomponent fibers may be those having cross sections that exhibit two or more distinct zones which differ in many respects. These differences may be in composition; or may be the same composition at a different temperature for each different cross section; or may be the same composition with different flow rates for each different cross section or with different I.V.'s (intrinsic viscosity) or with an additive in one of the components. The preceding list is only representative in part of various ways of achieving desirable properties such as self-crimping fibers, unusual dyeing effects and other effects.
When it is desired to have two or more different spinnable mediums come together within a spinneret assembly so as to subsequently issue from the assembly together as multicomponent fibers, the passages or conduits for the different spinnable mediums must intersect at precise angles to ensure that the intersection of the different spinnable mediums will be identical. It is difficult to drill two or more holes in a piece of metal so that they will intersect blindly in the middle portion of the metal. A drill bit will have a tendency to lead off from the intended drill path for various reasons. An uneven intersection will result in uneven flows of one spinnable medium relative to another one or more intersecting mediums.
Another problem that is associated with construction of spinneret assemblies is the resulting formation of areas along the flow path within the assemblies that will create secondary flows or pockets in which some of the spinnable medium will collect for a time and become heat degraded and thus subsequently affecting the overall quality of the spun filaments.
Accordingly, one of the objects of the invention is to provide a novel multiplate spinneret assembly construction adapted to produce multicomponent fibers, the intersections of the conduits being formed within a counterbore at the downstream face of one of the plates so as to bring together the different spinnable mediums in the central portion of the spinneret assembly for subsequent conjoint flow through the remaining part of the spinneret assembly for issuance through the individual spinneret orifices of the assembly as multicomponent fibers with intimate contact of the different spinnable mediums in each individual multicomponent filament along its length.
Another object is to provide a novel spinneret construction adapted to produce multicomponent fibers; the novel construction resulting in substantial reduction of secondary flows along the flow path for the spinnable mediums, which secondary flows would otherwise result in pockets in which some of the spinnable mediums would collect for a time and become heat degraded.
Still another object is to provide a multiplate spinneret construction adapted to produce multicomponent fibers, and into which two or more separate spinnable mediums may be introduced for separate paths of flow therethrough; the separate spinnable mediums coming together for conjoint flow prior to passing into and through the spinneret or orifice plate for subsequent exiting from each orifice of the orifice plate as a multicomponent fiber.
A further object is to provide a multiplate spinneret construction that will readily facilitate ease of cleaning and inspection.
SUMMARY OF THE INVENTION
These objects and others are obtained by the novel spinneret assembly, which includes three separate plates positioned in contiguous, coextensive alignment, with a separate annular channel between the first and second plates for each of two or more separate spinnable mediums. Each channel is in communication with passages formed in the second plate, which passages converge together with other passages carrying another one or more spinnable mediums at the downstream surface of the second plate within counterbore recesses to enable subsequent conjoint flow of the different spinnable mediums into and through the third or spinneret plate. The spinnable mediums exit from the spinneret plate as multicomponent fibers with intimate contact of the different spun mediums along the length of each individual filament. The length and diameter of the converging passages are correlated to the size of the flow path around the annular channels so that the maximum pressure drop in the converging passages will be greater than the maximum pressure drop in the annular channels by a factor of 10 or more to assure relative uniformity of filament deniers.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects inherent in the nature of the invention will become apparent to those skilled in the art to which this invention pertains from the description of the drawings and in the specification.
In the drawings:
FIG. 1 is a perspective view of the overall spinning apparatus including the spinneret assembly;
FIG. 2 is a cross-sectional view of the spinning apparatus;
FIG. 3 is a perspective view, partially broken away, of the cross section of the distribution plate or the upper plate or first plate, illustrating in phantom lines feed passages leading from the feed inlets;
FIG. 4 is an enlarged cross-sectional view of a portion of the lower plate or orifice plate or third plate and the intermediate plate, illustrating the counterbore recesses in conjunction with the converging feed passages;
FIG. 5 is a view of the approximate configuration of the cross section through individual fibers in which the multicomponents are in side-by-side configuration;
FIG. 6 illustrates in cross-sectional view a portion of a spinneret assembly of the prior art illustrating the blind intersection of two separate passages within the central portion of the spinneret plate;
FIG. 7 is another illustration of part of a portion of a cross section of a spinneret assembly of the prior art, illustrating probable flows and secondary flows or eddy currents;
FIG. 8 is a diagrammatic illustration in part of the annular grooves, the relationship of the feed passages relative to the annular grooves and to the openings in the annular grooves; and
FIG. 9 is a graphical illustration of the pressure drop of a quarter of one of the annular grooves as depicted in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The overall spinning apparatus is shown at 10 and comprises a conventional filter plate assembly 12 and the novel spinneret assembly 14 disposed within housing 15.
Filter Plate Assembly
In reference to FIGS. 1 and 2, the conventional filter plate assembly 12 comprises an upper or upstream filter plate 16 and a lower or downstream filter plate 18.
The upper or upstream filter plate 16 may be positioned in abutment on its upstream surface with at least two separate supply conduits 20, 22 through which separate spinnable fluid mediums A and B may be introduced to the spinning apparatus. The supply conduits lead into conical shaped or diverging passages 24, 26 in the upper filter plate, the diverging passages being provided with annular hubs 28, 30 on the downstream surface of the upper filter plate for a purpose to be described.
The lower or downstream filter plate 18 is positioned in abutment on its upstream surface with the downstream surface of the upper filter plate 16, and is provided within its upstream surface with circular recesses 32, 34 which are adapted to receive therewithin the annular hubs 28, 30 of the upper filter plate 16 with circular filter screens, 36, 38 being held in abutting relationship against wall surfaces within the recesses by the annular hubs. The hubs also serve to orient the upper filter plate with the lower filter plate. Conical-shaped passages 40, 42 within the lower filter plate and converging toward the downstream surface of the lower filter plate serve to convey the filtered spinnable fluid mediums to the spinneret assembly 14. Annular hubs 44, 46 are provided on the downstream surface of the lower filter plate for orienting the upper filter plate with the novel spinneret assembly.
Spinneret Assembly
The spinneret assembly 14 comprises three separate plates arranged to be positioned in stacked abutting relationship, one above the other.
The first plate or distribution plate 48 is provided on its upstream surface with at least two feed inlets indicated at 50, 52, the number of the feed inlets depending upon the number of separate spinnable fluid mediums desired to be processed through spinning apparatus 10 (the filter plate assembly, of course, being in correspondence with its number of passages). Circular recesses 54, 56 are formed within the upstream surface around the feed inlets for cooperatingly receiving in abutment with the wall surfaces of the recesses the annular hubs 44, 46 of the lower filter plate 18. The first plate is provided within its downstream surface with at least two annular grooves 58, 60 (the number of grooves corresponding to the number of separate spinnable fluid mediums to be processed), each of which is in communication with one of the feed inlets. Annular groove 58 communicates with feed inlet 50 through a pair of feed passages 62, 64 (FIGS. 3, 8), and annular groove 60 communicates with feed inlet 52 through a pair of feed passages 66, 68. It will be noted that the pairs of feed passages each diverge from their respective feed inlet to open into opposite sides of their respective annular groove for a purpose to be described.
The second plate or intermediate plate 70 is provided within its upstream surface with annular grooves 72, 74 which correspondingly mate, respectively, with annular grooves 58, 60 in the first or distribution plate 48 to define therewith annular channels 76, 78. A plurality of openings 80 (FIG. 8) are formed within each of the annular grooves 72, 74, the openings being spaced around the annular channels 76, 78. A plurality of feed passages 82 is provided, each feed passage extends from an opening 80 in annular channel 76 to convergingly meet in a bore recess 84 (FIG. 4) formed within the downstream surface of the second plate, with a similar feed passage 86 extending from each opening in annular channel 78. The bore recesses are preferably cone shaped in configuration (FIG. 4), as formed by a 90° countersink, for a purpose to be described. The second plate is further provided on its downstream surface with a pair of pins 88 for orienting the second plate with respect to the third plate or spinneret plate 90 described below.
The spinneret plate 90 is provided within its upstream surface with a plurality of bore recesses 92, which are preferably hemispherical shaped in configuration, as formed by a ball mill, for a purpose to be described, and which correspondingly mate, respectively, with the cone-shaped bore recesses 84 in the second or intermediate plate 70 to form a counterbore set. A pair of holes (not shown) are also formed within the upstream surface for receiving pins 88 of the second plate. Each hemispherical bore recess adjoins a lead hole 94 in the spinneret plate, which in turn leads into a capillary opening 96 of predetermined length. The diameter of the capillary opening determines the size of the orifice 98 within the downstream surface of the third plate or spinneret plate.
OPERATION
In the operation of the spinning apparatus, it shall be assumed for purposes of illustration, and as shown in the drawings, that only two separate spinnable fluid mediums, A and B, are involved. It should be understood, however, that more than two spinnable fluid mediums may be processed by the spinning apparatus of the invention, with the construction of the apparatus being modified, accordingly, within the teachings of this disclosure.
The spinnable fluid mediums, A and B, having different characteristics, enter the spinning apparatus 10 through supply conduits 20, 22, passing through the filter plate assembly 12 to the spinneret assembly 14.
Tracing for a moment only the path followed by one of the spinnable fluid mediums, A, the latter flows through feed inlet 50 of the distribution plate 48, and then subdivides for subsequent downstream flow through feed passages 62, 64, and exiting therefrom for flow into and around annular channel 76. The entry flow into the annular channel occurs at two locations opposed from each other. Thus, the flow from one feed passage only extends, upon channel entry, in each direction for one-quarter of the distance around the annular channel 76, as shown in FIG. 8. In this manner the maximum pressure drop, ΔP 2 , will occur through one-quarter of the distance, as illustrated by the arrow in FIG. 8.
Spinnable fluid medium B follows a similar-type flow path for subsequent entry and flow into and around annular channel 78.
The overall pressure must be sufficient for the spinnable mediums to fill completely the annular channels to assure subsequent flow through each of the openings 80 in each of the annular channels and into the plurality of respective feed passages 82, 86 in the second plate or intermediate plate 70 and on through the subsequent passages.
The spinnable fluid mediums A and B come together from the converging feed passages 82, 86 in the bore recesses 84 at the downstream surface of the intermediate plate for subsequent conjoint flow into the respective bore recesses 92 in the upstream surface of the spinneret plate 90, lead holes 94, capillary openings 96 and exit from the spinneret assembly through orifices 98 as multicomponent filaments 100 (FIG. 5) with intimate contact of the conjoined spun mediums along their lengths.
The size and length of the feed passages 82, 86 are such as to assure that the pressure drop, ΔP 1 , therethrough is far greater than the theoretical pressure drop ΔP 2 in the annular channels. In other words, ΔP 1 >>ΔP 2 .
As shown by the graph in FIG. 9, the total pressure drop, ΔP T , for the number of openings 80 around one-quarter of an annular channel will be equal to the sum of the pressure drops, ΔP 1 , in the feed passages 86, 82 and the pressure drops, ΔP 2 , in the annular channels 76, 78.
The pressure drop through the feed passages 86, 82 in the second plate must be greater than the maximum pressure drop encountered in the flow of the spinnable mediums through one-quarter of the annular channels by a factor of 10 or more. The feed passages 86, 82 and the respective annular channels must be appropriately formed in order to achieve this result. This is predicated, of course, on having only two opposed feed passages 62, 64 or 66, 68 for the respective annular channels. If there should only be one such feed passage for an annular channel, the flow would extend half way around the entire channel; and if there were more than two such feed passages for an annular channel the flow extent around the channel would be accordingly.
The pressure drop from the exit of one of the feed passages 62, 64, 66, 68 around the respective annular channel and through one of the feed passages 82, 86 to a bore recess 84 is ΔP T . ΔP T is equal to the sum of ΔP 2 , which is the pressure drop around the annular channel to a particular opening 80; and ΔP 1 , which is the pressure drop through the corresponding feed passage 82, 86.
For two feed passages such as 62, 64, or 66, 68, ΔP 2 would be a maximum for the opening 80 situated 90° from an exit of one of the feed passages 62, 64, 66, 68, as shown in FIG. 8.
The graph shown in FIG. 9 represents the total number of openings encountered by the flow of a spinnable medium, for the embodiment illustrated in the drawings, around one-quarter of an annular channel. For purposes of illustration, it is assumed that a feed passage 62, 64, 66, 68 upon opening into an annular channel will be directly above one of the openings 80. Thus the pressure drop with respect to that particular opening will be zero (as illustrated in the graph for the first bar representation of the opening).
If, however, the orientation of the first plate or distribution plate 48 relative to the second plate or intermediate plate 70 should be such as to cause such feed passage to open into the annular channel at a location somewhere between two of the openings 80, then the pressure drop of the first opening 80 in the quarter flow path around the annular channel would be greater than zero.
As is evident from the graph pressure drop, ΔP 2 , in an annular channel increases gradually from opening 80 to opening 80 around the quarter of the channel. Pressure drop ΔP 1 of a feed passage 82, 86, however, must not change from the first opening to the last opening in such quarter by more than 10 percent in order to assure sufficient flow of the spinnable mediums through each opening, and in turn assure relative uniformity of filament deniers. The indicated factor of 10 or more (above) will allow for no more than a 10 percent difference in denier among the filaments issuing at one time from the spinneret assembly. In other words, it is desired that the flow rates from each orifice 98 must be within 10 percent or less of each other.
FIG. 5 illustrates in exaggerated detail the multicomponent filaments 100 in cross section, with A' and B' representing, respectively, the spun medium of spinnable fluid mediums A and B. Although A' and B' are shown as being dark and light, this is only for illustration purposes since in actual practice they will probably be of similar color but varying in chemical or other characteristics.
PRIOR ART
FIGS. 6 and 7 have been illustrated in the drawings so as to disclose some problems commonly associated with construction of multicomponent spinneret assemblies, and as heretofore mentioned in brief.
FIG. 6 is an illustration from U.S. Pat. No. 3,166,788 in which "feeder ducts" 102 and 104 of the spinneret plate 106 are illustrated as making an even intersection as at 108. This is an example of a "blind" intersection which is difficult to make for a number of reasons including the undesirable aforementioned leading off of the drill bit away from the desired path. The intersection shown at 108 is theoretically desirable but in practice, from one spinneret assembly to the next and from one spinneret hole to the next, is difficult to obtain.
It is difficult to clean blind intersections in such spinneret assemblies, and even more difficult to inspect to see whether such intersections are clean.
The aforementioned difficulties are obviated in the novel spinneret assembly disclosed herein. The intersecting feed passages 82, 86 occur within the counterbore or bore recess 84; the bore recess thus corrects for any uneven intersection that may have occurred as a result of the drilling operation. There is no difficulty in cleaning the intersection because of its ready susceptibility to cleaning processes and inspection.
FIG. 7 is a portion of an illustration from U.S. Pat. No. 3,320,633 for the purpose of illustrating theoretical flow of spinnable mediums.
"Expansion chambers" 110 and 112 in the "meter" plate 114 have been formed in such manner that probably for many types of spinnable mediums, secondary flow or eddy currents would result in the corner areas such as at 116, 118, 120 and 122. In other words, such corner areas would constitute stagnation areas.
These difficulties are obviated in the novel spinneret assembly disclosed herein by streamlining the flows and eliminating corner areas. As heretofore described, the configuration of counterbore recess 84 is cone shaped with the result that the converging feed passages meet at opposed sides of the counterbore recess and substantially eliminate any corner areas. Since the counterbore recess 92 is hemispherical in configuration, the result is that the spinning medium enters from opposite sides of the cone-shaped counterbore recess 84 to merge together upon entry for subsequent smooth flow into the hemispherical-shaped counterbore recess and then into the lead hole 94. The counterbore recesses have thus minimized corner areas and in turn have thus contributed to such streamlining.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
The present invention relates to a spinneret assembly for producing multicomponent fibers, and particularly a spinneret assembly for producing multicomponent fibers of the side-by-side type.
Multicomponent fibers may be those having cross sections that exhibit two or more distinct zones which differ in many respects. These differences may be in composition; or may be the same composition at a different temperature for each different cross section; or may be the same composition with different flow rates for each different cross section or with different I.V.'s (intrinsic viscosity) or with an additive in one of the components. The preceding list is only representative in part of various ways of achieving desirable properties such as self-crimping fibers, unusual dyeing effects and other effects.
When it is desired to have two or more different spinnable mediums come together within a spinneret assembly so as to subsequently issue from the assembly together as multicomponent fibers, the passages or conduits for the different spinnable mediums must intersect at precise angles to ensure that the intersection of the different spinnable mediums will be identical. It is difficult to drill two or more holes in a piece of metal so that they will intersect blindly in the middle portion of the metal. A drill bit will have a tendency to lead off from the intended drill path for various reasons. An uneven intersection will result in uneven flows of one spinnable medium relative to another one or more intersecting mediums.
Another problem that is associated with construction of spinneret assemblies is the resulting formation of areas along the flow path within the assemblies that will create secondary flows or pockets in which some of the spinnable medium will collect for a time and become heat degraded and thus subsequently affecting the overall quality of the spun filaments.
Accordingly, one of the objects of the invention is to provide a novel multiplate spinneret assembly construction adapted to produce multicomponent fibers, the intersections of the conduits being formed within a counterbore at the downstream face of one of the plates so as to bring together the different spinnable mediums in the central portion of the spinneret assembly for subsequent conjoint flow through the remaining part of the spinneret assembly for issuance through the individual spinneret orifices of the assembly as multicomponent fibers with intimate contact of the different spinnable mediums in each individual multicomponent filament along its length.
Another object is to provide a novel spinneret construction adapted to produce multicomponent fibers; the novel construction resulting in substantial reduction of secondary flows along the flow path for the spinnable mediums, which secondary flows would otherwise result in pockets in which some of the spinnable mediums would collect for a time and become heat degraded.
Still another object is to provide a multiplate spinneret construction adapted to produce multicomponent fibers, and into which two or more separate spinnable mediums may be introduced for separate paths of flow therethrough; the separate spinnable mediums coming together for conjoint flow prior to passing into and through the spinneret or orifice plate for subsequent exiting from each orifice of the orifice plate as a multicomponent fiber.
A further object is to provide a multiplate spinneret construction that will readily facilitate ease of cleaning and inspection.
SUMMARY OF THE INVENTION
These objects and others are obtained by the novel spinneret assembly, which includes three separate plates positioned in contiguous, coextensive alignment, with a separate annular channel between the first and second plates for each of two or more separate spinnable mediums. Each channel is in communication with passages formed in the second plate, which passages converge together with other passages carrying another one or more spinnable mediums at the downstream surface of the second plate within counterbore recesses to enable subsequent conjoint flow of the different spinnable mediums into and through the third or spinneret plate. The spinnable mediums exit from the spinneret plate as multicomponent fibers with intimate contact of the different spun mediums along the length of each individual filament. The length and diameter of the converging passages are correlated to the size of the flow path around the annular channels so that the maximum pressure drop in the converging passages will be greater than the maximum pressure drop in the annular channels by a factor of 10 or more to assure relative uniformity of filament deniers.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects inherent in the nature of the invention will become apparent to those skilled in the art to which this invention pertains from the description of the drawings and in the specification.
In the drawings:
FIG. 1 is a perspective view of the overall spinning apparatus including the spinneret assembly;
FIG. 2 is a cross-sectional view of the spinning apparatus;
FIG. 3 is a perspective view, partially broken away, of the cross section of the distribution plate or the upper plate or first plate, illustrating in phantom lines feed passages leading from the feed inlets;
FIG. 4 is an enlarged cross-sectional view of a portion of the lower plate or orifice plate or third plate and the intermediate plate, illustrating the counterbore recesses in conjunction with the converging feed passages;
FIG. 5 is a view of the approximate configuration of the cross section through individual fibers in which the multicomponents are in side-by-side configuration;
FIG. 6 illustrates in cross-sectional view a portion of a spinneret assembly of the prior art illustrating the blind intersection of two separate passages within the central portion of the spinneret plate;
FIG. 7 is another illustration of part of a portion of a cross section of a spinneret assembly of the prior art, illustrating probable flows and secondary flows or eddy currents;
FIG. 8 is a diagrammatic illustration in part of the annular grooves, the relationship of the feed passages relative to the annular grooves and to the openings in the annular grooves; and
FIG. 9 is a graphical illustration of the pressure drop of a quarter of one of the annular grooves as depicted in FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The overall spinning apparatus is shown at 10 and comprises a conventional filter plate assembly 12 and the novel spinneret assembly 14 disposed within housing 15.
Filter Plate Assembly
In reference to FIGS. 1 and 2, the conventional filter plate assembly 12 comprises an upper or upstream filter plate 16 and a lower or downstream filter plate 18.
The upper or upstream filter plate 16 may be positioned in abutment on its upstream surface with at least two separate supply conduits 20, 22 through which separate spinnable fluid mediums A and B may be introduced to the spinning apparatus. The supply conduits lead into conical shaped or diverging passages 24, 26 in the upper filter plate, the diverging passages being provided with annular hubs 28, 30 on the downstream surface of the upper filter plate for a purpose to be described.
The lower or downstream filter plate 18 is positioned in abutment on its upstream surface with the downstream surface of the upper filter plate 16, and is provided within its upstream surface with circular recesses 32, 34 which are adapted to receive therewithin the annular hubs 28, 30 of the upper filter plate 16 with circular filter screens, 36, 38 being held in abutting relationship against wall surfaces within the recesses by the annular hubs. The hubs also serve to orient the upper filter plate with the lower filter plate. Conical-shaped passages 40, 42 within the lower filter plate and converging toward the downstream surface of the lower filter plate serve to convey the filtered spinnable fluid mediums to the spinneret assembly 14. Annular hubs 44, 46 are provided on the downstream surface of the lower filter plate for orienting the upper filter plate with the novel spinneret assembly.
Spinneret Assembly
The spinneret assembly 14 comprises three separate plates arranged to be positioned in stacked abutting relationship, one above the other.
The first plate or distribution plate 48 is provided on its upstream surface with at least two feed inlets indicated at 50, 52, the number of the feed inlets depending upon the number of separate spinnable fluid mediums desired to be processed through spinning apparatus 10 (the filter plate assembly, of course, being in correspondence with its number of passages). Circular recesses 54, 56 are formed within the upstream surface around the feed inlets for cooperatingly receiving in abutment with the wall surfaces of the recesses the annular hubs 44, 46 of the lower filter plate 18. The first plate is provided within its downstream surface with at least two annular grooves 58, 60 (the number of grooves corresponding to the number of separate spinnable fluid mediums to be processed), each of which is in communication with one of the feed inlets. Annular groove 58 communicates with feed inlet 50 through a pair of feed passages 62, 64 (FIGS. 3, 8), and annular groove 60 communicates with feed inlet 52 through a pair of feed passages 66, 68. It will be noted that the pairs of feed passages each diverge from their respective feed inlet to open into opposite sides of their respective annular groove for a purpose to be described.
The second plate or intermediate plate 70 is provided within its upstream surface with annular grooves 72, 74 which correspondingly mate, respectively, with annular grooves 58, 60 in the first or distribution plate 48 to define therewith annular channels 76, 78. A plurality of openings 80 (FIG. 8) are formed within each of the annular grooves 72, 74, the openings being spaced around the annular channels 76, 78. A plurality of feed passages 82 is provided, each feed passage extends from an opening 80 in annular channel 76 to convergingly meet in a bore recess 84 (FIG. 4) formed within the downstream surface of the second plate, with a similar feed passage 86 extending from each opening in annular channel 78. The bore recesses are preferably cone shaped in configuration (FIG. 4), as formed by a 90° countersink, for a purpose to be described. The second plate is further provided on its downstream surface with a pair of pins 88 for orienting the second plate with respect to the third plate or spinneret plate 90 described below.
The spinneret plate 90 is provided within its upstream surface with a plurality of bore recesses 92, which are preferably hemispherical shaped in configuration, as formed by a ball mill, for a purpose to be described, and which correspondingly mate, respectively, with the cone-shaped bore recesses 84 in the second or intermediate plate 70 to form a counterbore set. A pair of holes (not shown) are also formed within the upstream surface for receiving pins 88 of the second plate. Each hemispherical bore recess adjoins a lead hole 94 in the spinneret plate, which in turn leads into a capillary opening 96 of predetermined length. The diameter of the capillary opening determines the size of the orifice 98 within the downstream surface of the third plate or spinneret plate.
OPERATION
In the operation of the spinning apparatus, it shall be assumed for purposes of illustration, and as shown in the drawings, that only two separate spinnable fluid mediums, A and B, are involved. It should be understood, however, that more than two spinnable fluid mediums may be processed by the spinning apparatus of the invention, with the construction of the apparatus being modified, accordingly, within the teachings of this disclosure.
The spinnable fluid mediums, A and B, having different characteristics, enter the spinning apparatus 10 through supply conduits 20, 22, passing through the filter plate assembly 12 to the spinneret assembly 14.
Tracing for a moment only the path followed by one of the spinnable fluid mediums, A, the latter flows through feed inlet 50 of the distribution plate 48, and then subdivides for subsequent downstream flow through feed passages 62, 64, and exiting therefrom for flow into and around annular channel 76. The entry flow into the annular channel occurs at two locations opposed from each other. Thus, the flow from one feed passage only extends, upon channel entry, in each direction for one-quarter of the distance around the annular channel 76, as shown in FIG. 8. In this manner the maximum pressure drop, ΔP 2 , will occur through one-quarter of the distance, as illustrated by the arrow in FIG. 8.
Spinnable fluid medium B follows a similar-type flow path for subsequent entry and flow into and around annular channel 78.
The overall pressure must be sufficient for the spinnable mediums to fill completely the annular channels to assure subsequent flow through each of the openings 80 in each of the annular channels and into the plurality of respective feed passages 82, 86 in the second plate or intermediate plate 70 and on through the subsequent passages.
The spinnable fluid mediums A and B come together from the converging feed passages 82, 86 in the bore recesses 84 at the downstream surface of the intermediate plate for subsequent conjoint flow into the respective bore recesses 92 in the upstream surface of the spinneret plate 90, lead holes 94, capillary openings 96 and exit from the spinneret assembly through orifices 98 as multicomponent filaments 100 (FIG. 5) with intimate contact of the conjoined spun mediums along their lengths.
The size and length of the feed passages 82, 86 are such as to assure that the pressure drop, ΔP 1 , therethrough is far greater than the theoretical pressure drop ΔP 2 in the annular channels. In other words, ΔP 1 >>ΔP 2 .
As shown by the graph in FIG. 9, the total pressure drop, ΔP T , for the number of openings 80 around one-quarter of an annular channel will be equal to the sum of the pressure drops, ΔP 1 , in the feed passages 86, 82 and the pressure drops, ΔP 2 , in the annular channels 76, 78.
The pressure drop through the feed passages 86, 82 in the second plate must be greater than the maximum pressure drop encountered in the flow of the spinnable mediums through one-quarter of the annular channels by a factor of 10 or more. The feed passages 86, 82 and the respective annular channels must be appropriately formed in order to achieve this result. This is predicated, of course, on having only two opposed feed passages 62, 64 or 66, 68 for the respective annular channels. If there should only be one such feed passage for an annular channel, the flow would extend half way around the entire channel; and if there were more than two such feed passages for an annular channel the flow extent around the channel would be accordingly.
The pressure drop from the exit of one of the feed passages 62, 64, 66, 68 around the respective annular channel and through one of the feed passages 82, 86 to a bore recess 84 is ΔP T . ΔP T is equal to the sum of ΔP 2 , which is the pressure drop around the annular channel to a particular opening 80; and ΔP 1 , which is the pressure drop through the corresponding feed passage 82, 86.
For two feed passages such as 62, 64, or 66, 68, ΔP 2 would be a maximum for the opening 80 situated 90° from an exit of one of the feed passages 62, 64, 66, 68, as shown in FIG. 8.
The graph shown in FIG. 9 represents the total number of openings encountered by the flow of a spinnable medium, for the embodiment illustrated in the drawings, around one-quarter of an annular channel. For purposes of illustration, it is assumed that a feed passage 62, 64, 66, 68 upon opening into an annular channel will be directly above one of the openings 80. Thus the pressure drop with respect to that particular opening will be zero (as illustrated in the graph for the first bar representation of the opening).
If, however, the orientation of the first plate or distribution plate 48 relative to the second plate or intermediate plate 70 should be such as to cause such feed passage to open into the annular channel at a location somewhere between two of the openings 80, then the pressure drop of the first opening 80 in the quarter flow path around the annular channel would be greater than zero.
As is evident from the graph pressure drop, ΔP 2 , in an annular channel increases gradually from opening 80 to opening 80 around the quarter of the channel. Pressure drop ΔP 1 of a feed passage 82, 86, however, must not change from the first opening to the last opening in such quarter by more than 10 percent in order to assure sufficient flow of the spinnable mediums through each opening, and in turn assure relative uniformity of filament deniers. The indicated factor of 10 or more (above) will allow for no more than a 10 percent difference in denier among the filaments issuing at one time from the spinneret assembly. In other words, it is desired that the flow rates from each orifice 98 must be within 10 percent or less of each other.
FIG. 5 illustrates in exaggerated detail the multicomponent filaments 100 in cross section, with A' and B' representing, respectively, the spun medium of spinnable fluid mediums A and B. Although A' and B' are shown as being dark and light, this is only for illustration purposes since in actual practice they will probably be of similar color but varying in chemical or other characteristics.
PRIOR ART
FIGS. 6 and 7 have been illustrated in the drawings so as to disclose some problems commonly associated with construction of multicomponent spinneret assemblies, and as heretofore mentioned in brief.
FIG. 6 is an illustration from U.S. Pat. No. 3,166,788 in which "feeder ducts" 102 and 104 of the spinneret plate 106 are illustrated as making an even intersection as at 108. This is an example of a "blind" intersection which is difficult to make for a number of reasons including the undesirable aforementioned leading off of the drill bit away from the desired path. The intersection shown at 108 is theoretically desirable but in practice, from one spinneret assembly to the next and from one spinneret hole to the next, is difficult to obtain.
It is difficult to clean blind intersections in such spinneret assemblies, and even more difficult to inspect to see whether such intersections are clean.
The aforementioned difficulties are obviated in the novel spinneret assembly disclosed herein. The intersecting feed passages 82, 86 occur within the counterbore or bore recess 84; the bore recess thus corrects for any uneven intersection that may have occurred as a result of the drilling operation. There is no difficulty in cleaning the intersection because of its ready susceptibility to cleaning processes and inspection.
FIG. 7 is a portion of an illustration from U.S. Pat. No. 3,320,633 for the purpose of illustrating theoretical flow of spinnable mediums.
"Expansion chambers" 110 and 112 in the "meter" plate 114 have been formed in such manner that probably for many types of spinnable mediums, secondary flow or eddy currents would result in the corner areas such as at 116, 118, 120 and 122. In other words, such corner areas would constitute stagnation areas.
These difficulties are obviated in the novel spinneret assembly disclosed herein by streamlining the flows and eliminating corner areas. As heretofore described, the configuration of counterbore recess 84 is cone shaped with the result that the converging feed passages meet at opposed sides of the counterbore recess and substantially eliminate any corner areas. Since the counterbore recess 92 is hemispherical in configuration, the result is that the spinning medium enters from opposite sides of the cone-shaped counterbore recess 84 to merge together upon entry for subsequent smooth flow into the hemispherical-shaped counterbore recess and then into the lead hole 94. The counterbore recesses have thus minimized corner areas and in turn have thus contributed to such streamlining.
The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.