US3174183A

US3174183A - Spinneret plate

Info

Publication number: US3174183A
Application number: US187607A
Authority: US
Inventors: Arthur D Siegel
Original assignee: United States Rubber Co
Current assignee: Uniroyal Inc
Priority date: 1962-04-16
Filing date: 1962-04-16
Publication date: 1965-03-23
Anticipated expiration: 1982-03-23

Description

W my. 7/ /4,//// A a -A. D. SIEGEL SPINNERET PLATE Filed April 16, 1962 March 23, 1965 ATTORNEY 2 h w 2 a 4 I 6 W W ML r r 7 W 4 M J ig i 4/ 2;; k m R A United States Patent 3,174,183 SPEQNERET PLATE Arthur D. Siege], Cedar Grove, Ni, assignor to United States Rubber Company, New York, N.Y., a corporation of New Jersey Filed Apr. 16, 1962, Ser. No. 187,607 Claims. (61. 18-8) This invention relates to a spinneret plate for meltspinning of fine filament synthetic yarn. More particularly, it relates to a spinneret plate provided with very small diameter spinning holes of high capillary ratio.

The practice of making spinning holes in spinneret plates by drilling is well-known in the art. Similarly, the practice of employing pre-drilled inserts inserted in relatively large holes in a spinneret plate is also quite common. Even when very small diameter spinning holes are desired in such plates or inserts, it is feasible to drill such holes when length to diameter ratio is not too high, say, in the magnitude of 4/1 or less. However, the melt-spinning of high quality fine filament yarns from certain synthetics, including polypropylene, is believed to require or be materially aided by the employment of a spinneret plate having small diameter spinning holes of relatively high capillary ratios, that is, length to diameter ratios in excess of /1. Length to diameter ratios of up to 50/1 are believed to have a beneficial effect on such spinning, yarn tenacity and spinning stability being improved and melt fracture or irregular extrusion at high spinning rates being suppressed.

Ordinary drilling methods are not satisfactory for providing such fine, high capillary ratio spinning holes, because drills of the required diameter usually break long before they have reached the desired depth.

It is, accordingly, an object of this invention to provide a novel spinneret plate for melt-spinning of fine synthetic yarns having a plurality of small diameter, high capillary ratio spinning holes.

A still further object is to provide a novel seal between insert mounting holes in 1a spinneret plate and relatively thin walled inserts provided with high capillary spinning holes which are mounted in such mounting holes.

For a better understanding of the present invention together with other and further objects thereof, reference is had to the following description, taken in conjunction with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings:

FIG. 1 is a sectional view of a portion of a spinneret plate showing the structure of one spinning hole in said plate;

FIG. 1a is a larger scale, partially sectioned detail of FIG. 1 showing particularly the seal between the spinning hole insert and the mounting hole in the spinneret plate:

FIG. 2 is a partially sectioned view of a completely equivalent alternative form of the invention; and

FIGS. 3 through 8 illustrate six steps in the method of making the spinneret plate section illustrated in FIG. 1.

Referring now to the drawings, wherein like reference numerals denote corresponding parts throughout the several views, FIGS. 1 and 1a illustrate the construction of the spinneret plate of this invention in the region of one of the several spinning holes, this identical construction being repeated for each spinning hole in the spinneret plate. At each spinneret hole location, a mounting hole 1 is provided in the plate 2 extending completely therethrough from one face 3 of the plate 2 to the opposite fax 4. The hole 1 is comprised of a first bore 5 extending from one face 3 to a depth intermediate between the two

faces

3 and 4 and usually through somewhat more than one-half the thickness of the plate 2, and a smaller diameter second bore 6, coaxial with the first bore and 3,174,183 Patented Mar. 23, 1965 we C communicating between the bottom of said first bore and the opposite face 4. The junction or transition zone between the two coaxial bores 5 and 6 is characterized by a relatively sharp shoulder 7 at the plane of intersection of the smaller diameter bore 6 with the bottom of the larger diameter bore 5.

Mounted in hole 1 so that its end faces 11 and 12 are substantially flush with

faces

3 and 4 of the plate 2 is a slender insert 10. Insert 11) is comprised of a relatively large diameter zone 13 having an outside diameter slightly smaller than the inside diameter of the larger bore 5, a smaller diameter zone 14 having an outside diameter slightly smaller than the inside diameter of the smaller bore 6 and a tapered zone 15 providing a relatively gradual transition between the larger diameter zone 13 and the smaller diameter zone 14. Passing completely through insert 10 from the large end face 11 to the small end face 12 and substantially coaxial with insert 10 is a high capillary ratio spinning hole 16.

As noted previously with reference to the outside diameters of the several zones of the insert 10, there are slight clearances between larger diameter zone 13 and the bore 5 and between smaller diameter zone 14 and the smaller bore 6. However, tapered zone 15 is in tight interference fit relationship with shoulder 7, thereby providing a liquid-tight seal between plate 2 and insert 10 at the plane of shoulder 7. While, ideally, the sharp shoulder 7 might be chanacterized by a right angle step, it has been found that a shoulder angle on such as that formed by the intersection of the smaller diameter bore 6 with the conical impression 8 left by a drill point used for forming larger bore 5 will provide an adequate seal. This is approximately a 60 angle. However, because of the clearances between the insert 1% and the hole 1, a shoulder angle on which is approximately equal to the taper angle ,6 would admit the possibility of fluid leakage between the plate 2 and the insert 10.

While it is to be clearly understood that the spinneret plate which is the subject of this invention is normally provided with a multiplicity of spinning holes arranged in a suitable pattern, the method of making such a plate will be described herein in terms of making a single spinning hole, all of the spinning holes of the plate being of similar construction. In describing this method, reference is had particularly to FIGS. 3 through 8 taken in numerical order.

As shown in FIG. 3, spinneret plate 2 is first drilled with a bore 5 extending from one face 3 of the plate 2 to a depth intermediate between the

faces

3 and 4 and usually slightly more than one-half the distance between said two faces, the drill point leaving a conical impression 8 at the bottom of the bore 5.

Next, as shown in FIGS. 4 and 5, a smaller diameter bore 6 is drilled from the bottom of the bore 5 to the opposite face 4 of the plate 2. While it has been found helpful in achieving substantial coaxiality of bores 5 and 6 to start the drill for the smaller diameter bore 6 in the conical impression 8 at the bottom of the first bore 5, with adequate drilling jigs provided with hard collars, the same result could probably be achieved by drilling the two bores 5 and 6 from opposite faces of the plate 2.

Next, referring to FIG. 6, slender drawn tubing, such as that known as hypodermic tubing, having an outside diameter slightly smaller than the inside diameter of the larger bore 5, is cut to a length somewhat longer than the thickness of the plate 2. This tubing, being drawn, is provided with a central hole 16 having a much higher capillary ratio than could be achieved by drilling and having an outstandingly regular circular cross-section. Alternatively, tubing having a non-circular central hole may be used for spinning fibers of non-circular cross-section. As shown in FIG. 7, this tubing insert is then surface ground at one end to produce a zone 14 having an outside diameter slightly smaller than the inside diameter of the smaller bore 6 and a transition Zone between the smaller diameter zone 14 and the original diameter zone 13 having a relatively gradual taper. The length of smaller diameter zone 14 should slightly exceed the depth of the smaller bore 6 in the plate 2.

Finally, as shown in FIG. 8, the finished insert 10 is driven, smaller diameter end first, into mounting hole 1 in plate 2 until the tapered zone 15 of the insert 10 is in liquid-tight interference fit relationship with the shoulder 7 formed by the intersection of smaller bore 6 with the conical drill point impression 8. While it has been found that a satisfactory seal can be obtained by simply tapping the insert 10 into place with a hammer, equally good results could probably be achieved by pressing the insert 10 into place. It is believed that the sealing effect is at least enhanced by the employment of relatively thin walled inserts. Tubings having inside diameters of from .010" to .035" and wall thicknesses of from .005 to .010" have been found to seal tightly against the shoulder in the mounting hole when employed as inserts.

When the insert 10 has been pressed into sealed relationship with the hole 1, the end faces 11' and 12 of the insert extend beyond the

faces

3 and 4 of the spinneret plate 2. The plate 2 is, consequently, finished to the structure shown in FIG. 1 by grinding the end faces 11 and 12 of the insert 10 flush with the

faces

3 and 4 of the spinneret plate 2.

A 1" thick spinneret plate having spinning holes of .023 diameter and a /1 capillary ratio has been made by the method described herein and has per formed with good results, the spinning hole being arranged in three concentric circles of 1", 2" and 3" diameters containing, respectively, 5, 12 and 18 spinning holes. The inserts were made from .023" I.D., .036" O.D. stainless steel drawn hypodermic tubing cut to one and one-quarter inch length. For a distance of one-half inch from one end thereof, each insert was ground to .033" O.D., the transition zone from the .033" O.D. zone to the .036" OD. zone being a substantially uniform taper approximately long. Each mounting hole in the spinneret plate was drilled from the inside face to a depth with a .036" drill and was drilled through to the opposite face with a .033 drill. The drills tend to cut slightly oversize holes thereby providing the aforementioned slight clearances -for the inserts. The inserts were sealed in the mounting holes by tapping with a hammer. Clearance between inserts and holes has been found not to be critical and selective fitting is not necessary.

The structure shown in 'FIG. 2 is identical to that shown in FIG. 1 except that the insert 10 is assembled into a mounting hole 1a in a taper pin 9 which, in turn, is subsequently assembled into a tapered hole 17 in spinneret plate 2 and is then ground flush, becoming, for all practical operational purposes a part of the spinneret plate 2, itself. Taper pins 1 long by .250" diameter at the large end with a taper of A" per foot have been used successfully. The chief advantage'of using taper pins as opposed to mounting the spinning hole inserts ltl directly in the holes 1 drilled in the plate}, as shown in FIG. 1, is that individual taper plugs can be replaced or removed for maintenance without destroying the entire plate. It is to be noted, however, thatthe structure and method described and claimed herein are intended to apply to spinning hole assemblies of the type described whether made directly in mounting holes in the spinneret plate or in taper plugs or other inserts which are intended to be subsequently inserted in larger holes in 1a spinneret plate and to function therein essentially is a part of said plate.

While a preferred form of the invention has been shown and described herein, it will be appreciated that this is for the purpose of illustration and that modifications and changes may be made therein without departing from the spirit and scope of the invention.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. A spinneret plate assembly having at least one high capillary ratio spinning hole comprising:

(a) a plate provided with at least one mounting hole passing therethrough and having at least two zones of different diameters, the junction between at least two of saidzones of different diameters being characterized by a relatively sharp shoulder; and

(b) a tubular insert in each said mounting hole, said insert having a high capillary ratio spinning hole passing therethrough and an external surface of revolution including a tapered portion in liquid-tight contact with said shoulder of said mounting hole.

2. A spinneret plate assembly having at least one high capillary ratio spinning hole comprising:

(a) a plate provided with at least one mounting hole passing therethrough, said mounting hole including at least two bores of different diameters, the junction between at least two of said bores of different diameters being characterized by a relatively sharp shoulder; and

(b) a tubular insert in said mounting hole, said ininsert having a high capillary ratio spinning hole passing therethrough and an external surface of revolution including a relatively gradually tapered portion in liquid-tight driven contact with said shoulder of said mounting hole.

3. A spinneret plate assembly including:

(a) a plate having at least one hole extending therethrough from face to face, each such hole comprising a first bore opening on one face of said plate and a second bore of slightly smaller diameter than said first bore communicating between said first bore and the opposite face of said plate, said first and second bores being substantially coaxial, the junction between said second bore and said first bore defining a relatively sharp shoulder; and

(b) a tubular element having a high capillary ratio passage therethrough inserted in each said hole, the exterior surface of each said tubular element having a tapered section, said tapered section being in driven contact withsaid sharp shoulder of said hole, whereby an effective liquid-tight seal exists between said tapered section and said shoulder.

4. A spinneret plate assembly having at least one high capillary ratio spinning hole comprising:

(a) a plate provided with at least one mounting hole extending through the entire thickness of said plate from face to face thereof and having a zone of relatively small diameter adjacent to one face of said plate and at least one zone of larger diameter adjacent to said small diameter zone, the junction between said small diameter zone and said adjacent zone being characterized by a relatively sharp shoulder; and

(b) a number of tubular inserts corresponding to the number of said mounting holes, formed from drawn tubing, each at least as long as the thickness of said plate, each said insert having a uniform inside diam eter equal to the desired diameter of each spinning hole and an external surface of revolution, a length of said external surface of revolution adjacent one end of each said insert having a diameter slightly smaller than the diameter of said small diameter zone of its corresponding mounting hole and another length thereof, separated from said first mentioned length by a relatively gradually tapered length, having a diameter slightly smaller than the diameter of said larger diameter zone of its corresponding mounting hole adjacent to said small diameter zone of said mounting hole;

(0) each said insert being mounted, small diameter end first, in its corresponding mounting hole, from the side opposite said small diameter zone thereof, so that said tapered length of each said insert is in liquid-tight interference contact with said sharp shoulder of its corresponding mounting hole.

5. A spinneret plate assembly provided with at least one small diameter high capillary ratio spinning hole, each said spinning hole comprising:

(a) A first cylindrical hole in said plate extending from one face thereof to a plane intermediate between the two faces thereof, said first hole having a flat to relatively flat conical bottom;

(b) a second cylindrical hole in said plate of smaller diameter than said first hole, said second hole being substantially coaxial with said first hole and extending between the bottom of said first hole and the opposite face of said plate;

(0) said first and second holes together comprising a stepped mounting hole of two diameters the transition between which is characterized by a relatively sharp shoulder; and

(d) a tubular insert having a uniform inside diameter spinning hole and comprising a first tubular zone having an outside diameter less than the inside diam- 5 eter of said first hole and greater than the inside diameter of said second hole, a second tubular zone, substantially coaxial with said first tubular zone, having an outside diameter less than the inside diameter of said second hole, and a transition zone between said first and second tubular zones in the form of a relatively gradual taper;

(e) said insert being inserted in said mounting hole so that said transition zone of said insert is in liquidtight interference contact with the intersection of said second hole and said bottom of said first hole.

References Cited by the Examiner UNITED STATES PATENTS 2,341,555 2/44 Jones 18-8 2,618,989 11/52 Cupler 76107 2,879,676 3/59 Burkhardt et al. 76-107 3,006,026 10/61 Martin et al. 188 3,038,420 6/62 Smmohr 18-8 X FOREIGN PATENTS 1,102,340 3/61 Germany.

30,306 1910 Great Britain.

WILLIAM J. STEPHENSON, Primary Examiner.

ROBERT F. WHITE, Examiner.

Claims

1. A SPINNERET PLATE ASSEMBLY HAVING AT LEAST ON HIGH CAPILLARY RATIO SPINNING HOLE COMPRISING: (A) A PLATE PROVIDED WITH AT LEAST ONE MOUNTING HOLE PASSING THERETHROUGH AND HAVING AT LEAST TWO ZONES OF DIFFERENT DIAMETERS, THE JUNCTION BETWEEN AT LEAST TWO FO SAID ZONES OF DIFFERENT DIAMETERS BEING CHARACTERIZED BY A RELATIVELY SHARP SHOULDER; AND (B) A TUBULAR INSERT IN EACH SAID MOUNTING HOLE, SAID INSERT HAVING A HIGH CAPILLARY RATIO SPINNING HOLE PASSING THERETHROUGH AND AN EXTERNAL SURFACE OF REVOLUTION INCLUDING A TAPERED PORTION IN LIQUID-TIGHT CONTACT WITH SAID SHOULDER OF SAID MOUNTING HOLE.