US3070839A

US3070839A - Controlled quenching apparatus

Info

Publication number: US3070839A
Application number: US782745A
Authority: US
Inventors: Gordon W Thompson
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1958-12-24
Filing date: 1958-12-24
Publication date: 1963-01-01
Anticipated expiration: 1980-01-01

Description

Jan. I, 1963 G. w. THOMPSON CONTROLLED QUENCHING APPARATUS I Filed Dec. 24, 1958 3,fi70,839 Patented Jan. 1, 1963 3370,83? CONTROLLED QUENCHING APPARATUl Gordon W. Thompson, Hixon, Tenn, assignor to E. I. du Pont de Nemours and Company, Wilmington, Dei., a corporation of Deiaware Filed Dec. 4, 195%, Ser. No. 782,745 2 Claims. (Cl. 188) This invention relates generally to the production of synthetic filaments by melt-spinning and, more particularly, to a process and apparatu for cooling the molten filaments as they are extruded from a spinneret.

According to known procedures, melt-spun filaments travel a short distance from the spinneret before entering a quenching chamber in which a cross-current flow of the quenching medium is substantially uniform from end to end of the chamber.

The general objective of the present invention is the improvement of such properties of the yarn as its tenacity, drawability and uniformity, all of which improvements are reflected in subsequent handling of the yarn by way of reductions in the number of draw twister breaks, draw roll wraps, cleaner breaks, and the like.

The most important object of the present invention is the provision of a quenching process and apparatus in which the cooling potential of the quenching medium is increased as the distance from the spinneret increases.

Another important object of the invention is to provide a flow of the quenching medium, at its lowest cooling potential, immediately below the face of the spinneret.

With these and other objects in view, the practice of this invention involves generally the spinning of molten filaments through a quenching chamber, the introduction of an initially cross-current fi-ow of a suitable quenching medium into the chambenand control of the distribution of the quenching medium into the chamber by increasing its cooling potential as the filaments progress away from the spinneret.

The nature of the invention will be explained more fully hereinafter with reference to the accompanying drawing, wherein:

FIGURE 1 is a perspective view of the preferred embodiment, parts having been broken away to reveal details of construction;

FIG. 2 is a vertical sectional view, on a reduced scale, through the apparatus of FIG. 1; and

FIGS. 3-5 are vertical sectional views of alternate embodiments of the present invention.

In known processes of melt-spinning synthetic polymers, the spun filaments travel a short distance before entering an air-quenching chamber. Toward the remote end of the quenching chamber the filaments are gathered into a bundle by a convergence guide. In high-speed spinning, a steam-conditioning step is required, i.e., the filaments are passed from the convergence guide through a tube which is exposed tov a steam atmosphere. The steam conditoning causes the filaments to absorb moisture and to grow in length before reaching the windup bobbin, thus eliminating the possibility of such activity after the filaments have been wound up.

Referring now to FIGS. 1 and 2, the numeral designates an elongated chimney which is rectangular in cross section and provided with imperforate top, rear and side walls. The front of the chimney is partially covered by a louvered door 12 which terminates short or" the top wall and presents an open passage 14 for air discharging from chimney 1%. At the lower rear side thereof, the chimney It) communicates with a duct 16 through which quenching air at substantially room temperature is introduced. The interior of chimney 10 is partitioned by a perforated distribution plate 118 and a distribution screen or sheet 20 of a suitable foraminous material. Screen 20 is the boundary between a plenum chamber 10;; to which air is introduced from the inlet duct and a quenching chamber itiq through which the filaments pass. Between plate 18 and screen 20, two partial, flow-controlling screens 22 extend downwardly from the chimney top Wall and define the extent of a first flow zone in the upper region of quenching chamber 10g. It is preferred that screens 22 be placed upstream from screen 20 in order to minimize air turbulence in the chamber 10:

In operation, filaments are melt-spun from a spinneret 24 directly into the quenching chamber 101 through an opening 25 provided in the chimney top wall. As against the prior practice of spacing the chimney from the face of the spinneret, the top wall of chimney 10 is flush with the face of spinneret 24. The filaments 26 pass through the length of chamber 10: and, after being cooled therein, are gathered into a bundle by a convergence guide 23 before entering a steam conditioner 30. The quenching medium enters the plenum chamber 10p through duct 16, passes through distribution plate 18 and screens 24 22 to the quenching chamber llllq. As the medium passes through screens 29, 22, there is a pressure drop and a consequent velocity reduction relative to the flow through the single screen 29, i.e., the cooling potential of the medium in the first zone of the quenching chamber ltiq is considerably less than the cooling potential of the relatively unimpeded fiow through :the lower zones. Air flow from quenching chamber 10q is as indicated by arrows in FIG. 2. For best results, the cooling potential of the quenching medium should increase in the second zone to at least of its value in the first zone, and the first zone should extend through a distance of at least 6 inches from the face of the spinneret. Manifestly, the flow volume is varied with variations in the count and denier of the yarn being spun.

In a conventional quenching chamber, where there is a substantially uniform cross-current flow through the length of the chamber, the filaments are cooled at a high rate in the zone near the spinneret. In this zone, the filament temperature is in the range of 270-180 C. In the succeeding zones, the cooling rate decreases as the temperature of the filaments decreases below 180 C. By increasing the cooling potential of the medium in these succeeding zones, i.e., by increasing the flow, as disclosed herein, the cooling rate is increased in the zones of lower temperature.

In actual tests of the process and apparatus of the invention, the drawability of the filaments was improved considerably when compared with filaments which were spun through conventional equipment. The comparison showed a reduction of more than 50% in the number of broken filaments and draw roll wraps. The tenacity of the filaments was also substantially increased.

The same principle of increasing the cooling potential of the quenching medium with increases in the distance from the spinneret is employed in the apparatus embodiments of FIGS. 35. For example, in FIG. 3 the quenching medium enters the plenum chamber through duct 16' and passes through a pressure reduction nozzle 52 in a plate 54 which traverses the distance between the rear wall and the screen 20 to thus define an upper zone of reduced pressure and velocity in the quenching chamber. The medium is evenly distributed through the lower zones at a substantially greater rate. In FIG. 4, the medium which enters the plenum chamber passes through two pressure-reducing

screens

62 and 64 to define zones of relatively reduced flow. In FIG. 5, the central partial screen 22 extends farther into the chimney to define a second zone of intermediate flow in the quenching chamber. Additionally, the embodiment of FIG. 5 is provided with a closure plate 70 and an inclined imperforate door 72. The eifect of inclined door 72 is to induce a counterfiow in the lower zones of the quenching chamber. By the addition of closure plate 70, which has an opening 71 through which the filaments travel, a stronger counterfiow is induced in the lower zones and, to some extent, in the upper zone. This additive effect is manifestly dependent on the size of opening 71. Although the embodiment of FIG. 1 has been described as preferred, it should be noted that the modified apparatus of FIG. 5 is more effective for deniers of 840 and greater.

In carrying out the process, it is essential that, in addition to the conventional steps of spinning and steam-conditioning, the filaments be passed directly from the spinneret into a quenching chamber' In the quenching chamber, the cooling potential of the medium is increased in each of several successive zones between a minimum in the first zone to a maximum in the zone preceding the steam-conditioning step. In the apparatus embodiments chosen for illustration, this increase in cooling potential is accomplished by successively reducing the resistance to flow of the quenching medium between the plenum and quenching chambers.

Other advantages inherent in the practice of this invention will occur readily to those skilled in the art and, accordingly, its extent is intended to be limited only by the scope of the appended claims.

I claim:

1. In combination with a spinneret from which a plurality of filaments is extruded, a quenching apparatus comprising: an elongated chimney having side, front and back walls as well as an end wall fiush with the spinneret face, said end wall being provided with an opening through which the filaments pass for travel through the length of the chimney; a sheet of foraminous material dividing the chimney longitudinally into a quenching chamber through which the filaments travel and a plenum chamber, said front wall having an opening therein adjacent said end wall; and conduit means communicating with the plenum chamber for the introduction of a quenching medium, there being at least one additional foraminous sheet traversing said plenum chamber in close proximity to but spaced from said chimney-dividing sheet and in depending relationship to said end wall, said additional sheet being opposite said opening and extending only partially through the length of said plenum chamber.

2. The combination of claim 1 wherein is provided a,

second additional sheet having a length greater than the length of said one additional sheet and less than the length of said chimney.

References Cited in the file of this patent UNITED STATES PATENTS 1,959,414 Dreyfus et a May 22, 1934 2,273,105 Heckert Feb. 17, 1942 2,847,704- Scheers Aug. 19, 1958 2,947,029 Bakker Aug. 2, 1960 FOREIGN PATENTS 121,825 Australia July 23, 1946 85,774 Holland July 15, 1957

Claims

1. IN COMBINATION WITH A SPINNERET FROM WHICH A PLURALITY OF FILAMENTS IS EXTRUDED, A QUENCHING APPARATUS COMPRISING: A ELONGATED CHIMNEY HAVING SIDE, FRONT AND BACK WALLS AS WELL AS AN END WALL FLUSH WITH THE SPINNERET FACE, SAID END WALL BEING PROVIDED WITH AN OPENING THROUGH WHICH THE FILAMENTS PASS FOR TRAVEL THROUGH THE LENGTH OF THE CHIMNEY; A SHEET OF FORAMINOUS MATERIAL DIVIDING THE CHIMNEY LONGITUDINALLY INTO A QUENCHING CHAMBER THROUGH WHICH THE FILAMENTS TRAVEL AND A PLENUM CHAMBER, SAID FRONT WALL HAVING AN OPENING THEREIN ADJACENT SAID END WALL; AND CONDUIT MEANS COMMUNICATING WITH THE PLENUM CHAMBER FOR THE INTRODUCTION OF A QUENCHING MEDIUM, THERE BEING AT LEAST ONE ADDITIONAL FORAMINOUS SHEET TRAVERSING SAID PLENUM CHAMBER IN CLOSE PROXIMITY TO BUT SPACED FROM SAID CHIMNEY-DIVIDING SHEET AND IN DEPENDING RELATIONSHIP TO SAID END WALL, SAID ADDITIONAL SHEET BEING OPPOSITE SAID OPENING AND EXTENDING ONLY PARTIALLY THROUGH THE LENGTH OF SAID PLENUM CHAMBER.