US2341555A - Extrusion device - Google Patents

Description

Feb. 15, 1944. M 1 JONES 2,341,555

EXTRUS ION DEVICE Filed Dec. 12, 1941 i BY`*/ M Mq v ATTORNEY atented Feb. l5, 1944 UNITED STATES Y PATENT OFFICE EXTRUSION DEVICE Harry John Jones, Millburn, N. I., assigner to Baker & Co. Inc., Newark, N. J., a corporation of New Jersey 3 claims.

This invention relates in general to extrusion devices for the extrusion of organic viscous substances in the spinning of artificial filaments. In particular my invention deals with the provision of extrusion orifices in such extrusion devices.

`spinnerettes employed in the extrusion of organic substances in the spinning of rayon or other artificial filaments, fibers, or yarns, usually comprise a disc or cup-shaped extrusion device provided with a plurality of minute orifices through which the organic viscous material is extruded under pressure to form the shaped filament or the like. The minute orifices usually have 'a diameter of from 0.001" to 0.032". The walls of the fine cylindrical orifices may have various conguration such as straight, countersunk, parabolic, hyperbolic, or the like shapes. The walls of such orifices must be smooth and highly polished and be otherwise so constituted that the` viscous extrusion mass may flow freely over such walls without interruption or interference which may result from deposits of, or clogging by, the viscous mass. The diameter of the spinning disc or thespinning bottom of cup-shaped spinnerettes usually runs from 0.625 to 3", and there may be provided in such spinnerette anywhere from 7 to 100, and even more, minute spinning orifices.

Where the spinnerette is subjected to relatively low pressure, and where the spinnerette wall thickness to be pierced is relatively small, no great difficulty is experienced in the formation oi suitable orices therein. Difficulties are, however, experienced in the formation of minute orifices as heretofore known if the spinnerette wall thickness to be pierced is relatively great, as where the spinnerette has to withstand considerable pressure, and such diiiiculties are particularly great when the spinnerette consists of metal which is inherently difficult to machine.

It is, therefore, one object of my invention to provide easily manufactured, suitable extrusion orifices in spinnerettes wherein the wall`thickness to be pierced is relatively great. It is another object of my invention to provide such orifices in spinnerettes of `difilcultly machineable metal and in particular in such spinnerettes which in operation have to withstand considerable pressure. Other objects and advantages of my invention will appear from the description of my invention hereinafter following.

This application is a continuation-in-part of my earlier application Serial No. 267,582, filed April 13, 1939.

'I'he difficulties heretofore referred to in the provision of fine extrusion orifices of suitable character are experienced primarily when the wall thickness to be pierced approaches and exceeds 0.06". spinnerettes having a wall thickness of from 0.06" to about 0.4", and particularly such spinnerettes of hard and strong and, therefore, diicultly machineable metal, are, however, highly desirable in processes involving extrusion of the Viscous extrusion mass under pressure.

The orifice provided in such thick-walled spinnerettes in accordance with my invention consists oi an outlet portion with cylindrical wall, an inlet portion comprising a counterbore having an approximately straight cylindrical wall, and an intermediate portion having a tapered conical wall directly connecting the end -of the inlet portion with the beginning of the outlet portion.

The nature of my invention is illustrated in the accompanying drawing in which Figure 1 is a transverse vertical sectional view on a greatly enlarged scale through an extrusion apparatus including a spinnerette embodying my Y invention.

Figure 2 is a top plan view/of the spinnerette.

Figure 3 is an edge elevational view of an extrusion disc.

Figure 4 is a top plan view of the extrusion disc. and

Figure 5 is a fragmentary enlarged vertical sectional view through the spinnerette wall, showing in detail the form of the extrusion orifice.

'The extrusion device embodying my invention may be utilized in many types of extrusion apparatus, but for the purpose of illustration I have fragmentarily shown one type of apparatus which includes a tube or pipe A through which the viscous material to be extruded into filaments is supplied. 'I'he extrusion device or spinnerette B embodying the invention is connected to the end of this tube in the usual way by a coupling C.

As shown, one form of the spinnerette comprises a cup-shaped body I of metal which has a bottom wall 2 and cylindrical walls 3. At the mouth of the cup is provided a peripheral flange 4 which is utilized for clamping the spinnerette,

for example, on the end of the extrusion tube or.

pipe Avbetween the gaskets 5. 'Ihe bottom wall 2 has a plurality of extruding orifices or holes 6 ner and has a plurality of extruding orifices or holes 8.

In essence, the inlet portion of each extrusion hole 6 or 8 comprises a counterbore I0 having straight cylindrical walls and which may have a 4rounded or bevelled edge II, while the outlet portion I2 of the hole is of substantially smaller diameter than the inlet portion and has straight and cylindrical walls. The diameter of the outlet portion I2 which actually forms the fiber may be .030 more or less, as heretofore. Between the inlet and outlet portions, the hole has tapering walls I3 merging into and connecting the walls of the inlet and outlet portions. In the use of a spinnerette according to my invention, the extrusion mass enters the hole in the upper inlet portion I0, proceeds through the intermediate tapered portion I3 and is finally extruded through the lower or outlet portion. Where the thickness of the spinnerette disc or bottom 2 is great, the upper portion comprising the counterbore will be longer than in the case of a spinnerette disc or bottom having a relatively smaller thickness.

Preferably, although not necessarily, the length of each of said inlet and outlet ends respectively approximately equals the diameter thereof, and the diameter of the tapered intermediate portion at any given point in its length is equal to the distance of said point from the outlet extremity of the hole. These relative dimensions are indicated on the drawing by the legends .0:r", .0y" and .0z". Also, preferably the angle of taper of the walls I3 is of the order of fifty-three to sixty degrees.

The spinnerette of my invention is designed for the extrusion of organic viscous substances, including also synthetic organic substances, such as cellulose, cellulose derivatives, and the like. The spinnerette is particularly useful in the extrusion of synthetic polyamides and other polymerization products of fiber forming ability such, for instance, as those described in United States Letters Patents No. 2,071,250, No. 2,071,251, No. 2.071.252, No. 2,071,253 and No. 2,130,945, which are customarily spun under high pressure. In the acetate or cuprammonium processes, such spinnerettes constructed of nickel or nickel alloys, e. g. 70% nickel and 30% iron, or 40% nickel and 60% copper, stainless steel, tantalum, etc., are quite satisfactory. In the spinning of the aforesaid synthetic polyamides, however, a spinnerette constructed of chromium steel alloy containing from 14% to 20% chromium and substantially free from nickel, i. e. containing less than about 2% nickel, is most advantageous. All such metals as specifically described are difficult to machine, however, and when the spinnerette constructed thereof has a wall thickness in excess of 0.06" the provision of orifices shaped as herein described is particularly desirable.

The nature of the orifice provided in accordance with my invention is such that it can be formed easily in thick bottom spinnerettes, even when such spinnerette bottoms consist of metal difficult to machine. It is impossible to produce fine holes as heretofore known having smooth and highly polished holes free from irregularities in spinnerette discs or bottoms having a substantial thickness as described. Holes as heretofore known in spinnerettes, such as straight, countersunk, hyperbolic or parabolic, are either impossible or impractical to produce in discs or spinnerette bottoms having a thickness greater than approximately 0.06", particularly when the .bottom and the spinning orifices.

spinnerette construction material is of a nature which makes it difficult to machine. On the other hand, it is very easy to produce in such spinnerette disc or bottoms, holes according to my invention. The shaped orifice according to my invention makes it possible to provide such orifices with smooth and highly polished walls free from any recesses, irregularity or jaggedness, and the surface of the orifice walls is continuous from the very inlet to the final outlet so that the walls guide and direct the viscous mass over a continuous homogeneous fiow surface at a desirable flow angle toward and then through the extremely fine straight exit or outlet portion in a free and easy flow, thereby avoiding as far as possibleany deposition of such viscous mass on the walls of the orifices. ging, in part or in whole, of the orifice by the viscous mass is thereby largely avoided, and the quality of the resultant filament product improved.

The provision of orifices in accordance with my invention also makes it possible to provide, for high pressure spinning operations, a spinnerette with relatively thick bottom, as described, and having orifices with proper directional flow surface without unduly weakening the strength of the spinnerette bottom. The provision of a straight cylindrical hole, if possible at all in thick bottomed spinnerettes, would cause an undue back pressure necessitating a further increase in the thickness of the spinnerette bottom, with consequent increase in manufacturing difficulties and operating handicaps. The provision of a countersink, in connection with a straight cylindrical outlet portion of desired length, or the provision of parabolic or hyperbolic orifice walls would largely eliminate such undue back pressure but would, if such orifices were possible at all from a manufacturing standpoint in thick bottomed spinnerette bottoms of diflicultly machineable metal, result either in the elimination of the desir'ed flow taper of 53 to 60 at the cylindrical outlet portion, or in the necessity of extremely large openings at the inside surface of the spinnerette bottom and a consequent lowering of the strength of such bottorn, thereby impairing the efiicient operation of the spinnerette and destroying the very purpose of the initial requirement for a thick bottomed spinnerette of hard and strong metal. The provision of orifices shaped as heretofore known in thick bottomed spinnerettes constructed of hard and strong metal, if possible at all from a manufacturing point of view, would, therefore, result in impractical spinnerettes with unsatisfactory fiow characteristics and unsatisfactory strength, and would, likewise. seriously limit the number of orifices in such spinnerettes. The orifice herein described, however', does make it possible to cause the viscous mass to fiow into the cylindrical outlet portion of the orifice at any desired fiow angle without in'any way unduly weakening the strength of the spinnerette bottom, a strength which is required in order toavoid deformation of the spinnerette In the extrusion under pressure of fiber forming polyamides, for instance, it has been possible to thus manufacture easily chromium alloy spinnerettes in the form of discs of a diameter of about 2.03", and a thickness of 0.187", having from 7 to 58 orifices of the type here described, whereas it would be impossible to provide like spinnerettes with orifices shaped as heretofore.

Clogthe viscous mass.

'I'he term bottom as herein used means that part of the spinnerette through which the extrusion orices are provided.

Both surfaces, i. e. the inside as well as the y outside surfaces, of the spinnerette bottom are smooth and do not have any projections which would, on the inside surface, interfere with the free flow of the viscous mass and would, on the outside surface, prevent cleaning of the spinnerettes by wiping. Likewise, the orifice is constituted integrally in the metallic `spinnerette bottom and the walls thereof constitute a smooth and uninterrupted homogeneous flow surface for What I claim is:

1. A spinnerette capablebf withstanding high operating pressure with metallic bottom having a substantially uniform thickness of from 0.06 to 0.4", said bottom being provided with a plurality of extrusion orices formed therethrough 'consisting of an outlet portion with a straight operating pressure having a bottom of chromium alloy steel containing 14% to 20% chromium and of a uniform thickness of from 0.06" to 0.4", said bottom being provided with a plurality of extrusion orices formed therethrough, said orices consisting of an outlet portion with a straight cylindrical wall, an inlet portion comprising a counterbore having a substantially straight cylindrical wall, and an intermediate portion having a tapered wall directly connecting `the end of the inlet portion with the beginning of the outlet portion, the walls of said three portions forming a smooth and uninterrupted integral flow surface.

3. A spinnerette capable of 'withstanding high operating pressure with a metallic bottom having a substantially uniform thickness of from 0.06" to 0.4", said bottom being provided with a plurality of extrusion orifices formed therethrough consisting of an outlet portion with a straight cylindrical wall, the inlet portion comprising a counterbore having a substantially straight `cylindrical wall, and an intermediate portion having a tapered wall directly connecting the end of the inlet portion with the beginning of the outlet portion, said tapered wall having a flow taper of approximately 53 to 60 at the cylindrical outlet portion, the walls of said portions forming a smooth and uninterrupted integral flow surface.

HARRY JOHN JONES.

Images