US 3336633 A
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Description (OCR text may contain errors)
T.-A. CURRAN, JR
SPINNERET ASSEMBLY Filed Dec.
Aug. 22, 1967 United States Patent 3,336,633 SPINNERET ASSEMBLY Thomas A. Curran, In, Claymont, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Dec. 13, 1365, Ser. No. 513,389 3 Claims. (Cl. 188) This invention relates to the extrusion of fiber-forming compositions into filamentary form. More particularly, it relates to an improvement in the apparatus which is employed in the spinning process.
In the early days of spinning synthetic filaments, a simple filtration element and a plain spinneret plate were used. However, as demands for better and more uniform products were made, a more complicated spinneret assembly has been required. As a minimum, a metering plate is now used ahead of the spinneret plate. Such a metering plate is shown by Cobb in US. 3,095,607. In addition to the requirements for better and more uniform products, more complicated assemblies are required for the newer composite filaments such as side-by-side filaments and sheath-core filaments. In a modern spinning machine with many spinning positions, a large number of spinneret assemblies are needed. These complicated assemblies are costly for spinning one count, that is, a certain number of filaments with a total fixed denier, forming a bundle or thread. In the past when the count was changed, e.g., from 30 filaments to 25 filaments in the thread, all new plates were used. Today a fiber producer is required to supply many different counts. The total investment cost in the distribution, metering, and spinneret plates for all required counts is excessive. Further, with all these plates, it is relatively easy for the person putting together a spinneret assembly to become confused and use the wrong plates, resulting in the Wrong product being produced.
The principal object of this invention is to provide an improved spinneret assembly which can be used to spin a number of thread counts with a minimum of diiferent plates. In achieving this objective, I not only reduce investment and operating costs but also the possibility of operator error.
The above and other objectives and advantages have been accomplished with a spinneret assembly including a sandholder through which molten polymer is pumped to stacked metering and spinneret plates. Each of the plates is provided with a pattern of holes which are uniformly spaced in one of the patterns. In the other pattern, there are fewer holes but each is in communication with a hole in the one pattern.
In the drawings,
FIGURE 1 is an axial, longitudinal section of a typical spinneret assembly;
FIGS. 2 and 3 are diagrammatical illustrations of the hole alignment when spinning two different thread counts; and
FIG. 4 is a fragmentary, detailed, plan view of the stacked metering and spinneret plates described hereinafter.
As shown in FIG. 1, a typical spinneret assembly of the type disclosed by Cobb includes an open cap 12 which holds spinneret plate 14, metering plate 16, distribution plate 18, and screen 20 in stacked relationship with respect to a holder 22. There is a cavity 24 in holder 22 which is filled with a filtering medium 26 such as sand. Plate 18 is provided with a plurality of distribution holes 28. The filtering medium 26 is prevented from entering holes 28 by the screen 20. A recess in the bottom of plate 18 leaves a distribution space 30 between plates 16, 18. Plates 14, 16 are provided with spinning nozzles 32 and metering holes 34, respectively, all of which have compound shapes including both a counterbore and a minute capillary. Each metering hole 34 is on a common axis and in communication with its companion spinning nozzle 32.
In operation, molten polymer is pumped to cavity 24, filtered by medium 26, and flows through screen 20 and distribution holes 28 into the distribution space 30. A portion of polymer is metered by each hole 34, flows into the aligned spinning nozzle 32, issues from the nozzle as a filament and is quenched by cross-flow or radial quenching or by any other well-known quenching technique. After quenching, the individual filaments are combined into one thread or a plurality of threads, depending upon the final product desired, led to a suitable windup and packaged.
In an actual embodiment, thirty-five nozzles 32 are spaced equiangularly in a circular pattern. Present practice calls for an' equal number of metering holes 34 in plate 16. In FIG. 2, such a one-to-one relationship has been shown diagrammatically for a group of seven nozzlehole pairs. With equal numbers of holes in plates 14, 16, both must be changed when it is desired to change yarn counts and spin a greater or lesser number of filaments.
According to the present invention, it is economical and quite feasible to use only one spinneret plate 14. For example, when it is desired to spin thirty filaments instead of thirty-five, it is only necessary to install a new metering plate 16 having thirty holes which communicate with thirty of the holes in spinneret plate 14. In FIG. 3, such a seven-to-six relationship has been shown diagrammatically for a group of seven nozzles 32 and six metering holes 34, i.e., every seventh hole in the circular pattern of otherwise uniformly spaced metering holes 34 has been omitted. This relationship will also be apparent from the fragmentary illustration of plates 14, 16 in FIG. 4.
Within the limits of practicality, other nozzle-hole relationships can be used, for example, with the illustrated circular pattern of thirty-five nozzles 32, every fifth metering hole 34 can be omitted without adverse effect on the quenching, convergence and windup systems. Furthermore, the same concepts are applicable to different patterns, for example, when the spinning nozzles are spaced uniformly in rows. With nondegrading polymers, either of plates 14, 16 can be changed. Instead of the illustrated stack of three plates 14, 16, 18, some assemblies employ either a simple metering plate, a simple distribution plate or a complex set of distribution plates in conjunction with the spinneret plate. Other modifications and adaptations of a similar nature will occur to those skilled in the art and yet be within the spirit of the present invention which accordingly is intended to be limited only by the scope of the appended claims.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. A spinneret assembly comprising stacked metering and spinneret plates, each provided with at least one pattern of spaced holes, the holes in one of said patterns being spaced uniformly, there being fewer holes in the other pattern, each hole in said other pattern being in communication with a hole in said one pattern.
2. The assembly of claim 1 wherein said patterns are circular, the holes in said one pattern are spaced equiangularly and each hole in said other pattern is radially aligned with a hole in said one pattern.
4 3. The assembly of claim 2 wherein each hole in said other pattern is coaxial with a hole in said one pattern.
References Cited UNITED STATES PATENTS 2,763,374 9/1956 Corbett 18-l2 X 2,771,636 11/1956 McIntosh et al 1812 2,999,274 9/1961 Silas et al 18-12 X 3,095,607 7/1963 Cobb l88 WILLIAM J. STEPHENSON, Primary Examiner.