US3594878A

US3594878A - Process and apparatus for texturizing yarn

Info

Publication number: US3594878A
Application number: US848875A
Authority: US
Inventors: William D Porter
Original assignee: Northrop Carolina Inc
Current assignee: Northrop Grumman Systems Corp
Priority date: 1969-08-11
Filing date: 1969-08-11
Publication date: 1971-07-27
Anticipated expiration: 1988-07-27

Abstract

A method and device for crimping continuous filament yarn comprising providing a gas-actuated aspirator tube which serves to pull the yarn from its source and direct it to a crimping region which comprises a diffuser means downstream from the aspirator which separates the gas from the yarn, crimps the yarn and serves as a pressure means for forcing the yarn into a heater region where the crimping is set.

Description

United States Patent Inventor William D. Porter Asheville, N.C.

Appl. No. 848,875

Filed Aug. 11, 1969 Patented July 27, 1971 Assignee Northrop Carolina, lnc.

Swannanoa, N.C.

PROCESS AND APPARATUS FOR TEXTURIZING YARN 13 Claims, 1 Drawing Fig.

US. Cl 28/1.3, 28172.1 1

Int. Cl D02g l/OO FieldofSearch ..28/1.3, 1.4,

[56] References Cited UNITED STATES PATENTS 3,256,582 6/1966 Burleson 28/1.3 3,296,677 1/1967 Chase 28/1.3 3,303,546 2/1967 Van Blerk 28/l.3 3,343,240 9/1967 Parmeggiani et al. 28/1 .3 3,373,470 3/1968 Joly 28/72.11 3,409,956 1 H1968 Longbottorn et a1. 28/1.3

Primary Examiner-Louis K. Rimrodt AttorneysSokolski and Wohlgemuth and W. M, Graham ABSTRACT: A method and device for crimping continuous filament yarn comprising providing a gas-actuated aspirator tube which serves to pull the yarn from its source and direct it to a crimping region which comprises a diffuser means downstream from the aspirator which separates the gas from the yarn, crimps the yarn and serves as a pressure means for forcing the yarn into a heater region where the crimping is set.

lllllll l' Q a PAIENTED JUL2 1 an R. m R ND. WM mm L M w SOKOLSK/ 8 WOHLGE MU TH PNEUMATIC VIBRA TOR PROCESS AND APPARATUS FOR TEXTURlZlNG YARN Considerable technology and prior patented art exist in the field of crimping of filaments of synthetic fibers such as rayon, nylon, acetate, acrylate, polyesters and the like. Generally the crimping of these fibers is accomplished by mechanically stuffing them into a tube or other suitable container whereupon they fold upon themselves under the pressure of the feeding action. While in the container, and in a folded form, they are heated to permanently set the crimp. The previous technology has dealt with the problems of obtaining a proper residence time for the filaments during the heat setting thereof. In order to produce a suitable product the fibers should all be subjected to essentially the same residence time in the heated region where they have been stuffed and crimped.

In most all of the prior devices, the yarn is fed to the stuffing chamber by a pair of feed rollers with various mechanical and electromechanical means for controlling the rate at which the fibers are introduced and removed from the chamber. As aresult, complex mechanical and electrical means have been devised for controlling the rate at which the feed rollers feed the fibers to the stuffing chamber and/or the means by which the fibers are released or taken up from the chamber. Such prior means are not only complex and thus subject to breakdown and repair, but further they considerably increase the cost of the crimping operation.

Thus, an object of this invention is to provide a process and apparatus to simplify the crimping of yarn.

Another object of this invention is to provide a process and apparatus having few, if any, moving parts to be utilized in crimping yarns.

Still another object of this invention is to provide a process and apparatus for crimping of yarns which is relatively low cost.

Still one other object of this invention is to provide a process and apparatus which can crimp yarns at higher speeds than those utilized on mechanically fed stuffer box crimpers currently in use.

The above and other objects of this invention are accomplished by a process and associated apparatus which comprises an aspirator tube disposed downstream from the storage spool of the yarn to be crimped. The yarn is first directed to an inlet tube whose end is adjacent an inlet of the aspirator. The pressurized gas which is directed through the aspirator tube serves to create a vacuum in the inlet through a venturi effect, thus sucking the yarn through the inlet tube. After the yarn passes through the inlet tube, it continues through the aspirator which terminates in a nozzle exit area where a highvelocity stream of gas further tensions and propels the yarn forward, finally expelling the yarn and the converging gas to a diffuser. The diffuser can, for example, be a tube having a plurality of perforations in the outer wall. The diffuser is of a diameter and length sufficient to accumulate a configuration of packed yarn suitable to developing random or oriented yarn crimps of the desired amplitude and frequency. This is accomplished by placing an initial blockage at the downstream end of the diffuser tube. The holes or perforations in the walls of the diffuser tube allow the gas to separate from the yarn without allowing yarn blowback or escape. As the diffuser plugs with yarn, and begins to build backward toward the aspirator, the holes in its surface are blocked by the yarn plug,

- thus reducing the area through which the gas can escape. This causes a pressure buildup in the diffuser. This means for blocking the yarn from exiting the diffuser is then removed and the plug of yarn remains static in the diffuser until the diffuser fills and covers sufficient gas exit holes to cause the back pressure to build up to a point where the plug of yarn will be pushed forward from the tube by gas pressure.

Once the process is started, and the blockage means is removed, it becomes continuous with a steady plug of yarn existing in the diffuser tube and moving on from it into a heater region where the yarn is set in the crimp. The yarn is then directed from the heater to an area where all heat above ambient is removed. This area of the apparatus serves as a reservoir for accumulated yarn in which a continuous process can take away the yarn, accounting for slight variations in crimp level without pulling excessive tensions in the yarn or moving the reservoir level below a point where it has been adequately cooled.

In one embodiment of the invention the aspirator section of the device can be vibrated so as to randomly position the yarn in a crimped manner within the diffuser tube.

It is believed that the invention will be better understood from the following detailed description and drawing in which:

The FIGURE is a partially cross-sectioned pictorial representation of the apparatus of the invention to perform the crimping process.

Turning now to the FIGURE, there is seen a spool of continuous filament yarn 11. The yarn 13 can be directed to the device 15 of the invention by means of an idler roller 17 or other suitable guide means, depending upon the location of the spool relative to the device 15. In addition to feeding the yarn from a spool, it can be fed directly from a continuous spinning process as well.

The device 15 of the invention includes an end fitting 19. Threadably inserted in the forward closed end 21 of the fitting 19 is an inlet tube 23. lntersecting fitting 19 is an inlet air line 25. Tight fitted "or secured by other means to the downstream and open end 27 of fitting 19 is an aspirator tube 29. The aspirator tube 29 is provided with a central passageway 31 through which the yarn 13 passes as it comes from inlet tube 23. At the upstream end 33 of the aspirator, the area surrounding the central passage 31 is milled or formed conically at 35 to provide an enlarged inlet opening. Likewise, the downstream end of the inlet tube 23 is correspondingly formed at 37 to match the wall portion 35 at the inlet of the aspirator. When the inlet tube 23 is seated as shown in the FIGURE, a concentric convergent inlet nozzle 39 is thus formed between the end 37 of the inlet tube in the portion 35 of the aspirator.

As can be seen, the inlet 39 is directed downstream. Thus, the air entering from inlet 25 will fill chamber 41 between the inlet tube and the fitting 19 and then pass through the inlet nozzle 39 in a downstream direction, thus resulting in a venturi-type effect. This creates a partial vacuum in the inlet tube 23 serving to draw yarn into the device. The center passage 31 slightly diverges from the inlet nozzle 39 thus serving to increase the gas velocity. The downstream end of the aspiratorv 29 is provided with a divergent portion 43 formed in the walls of the aspirator. This serves mainly to adapt the aspirator to diffuser tube 45. Further, the divergence serves to additionally increase the velocity of the exit gas and thus to further tension and propel the yarn 13 forward, expelling it into a diffuser tube 45. I

The diffuser tube 45 may be attached to the aspirator 29, or in the embodiment shown, slightly separated therefrom. The difiuser has a diameter and length sufficient to accumulate a configuration of packed yarn and is suitable for developing random or oriented yarn crimp of the desiredamplitude and frequency. This is accomplished by causing the yarn to fold spirally or otherwise bend to form a desirable texture geometry when eventually heat-set in this shape. In the embodiment shown in the drawing, a pneumatic vibrator 47 is connected to the aspirator 15. The vibrator 47 causes the aspirator to vibrate and thus control the point at which the yarn l3 impinges into the yarn plug 49 located in the diffuser. This, thus, in effect controls thelength of the folds formed by the yarn after it is packed into the plug so alternative to vibrating the aspirator 15, the diffuser could be vibrated to accomplish the same result.

The crimp of yarn can be classified into two broad categories: One is a planar crimp in which all the bends of the yarn lie in a single plane. The other class is a three-dimensional crimp in which the bends may be either randomly oriented as to the plane in which they lie, or symmetrically arranged. Although a pneumatic vibrator is shown attached to the aspirator, this will not be required in all instances since there is significant turbulence in the impinging air leaving the exit nozzle portion 43 of the aspirator, which tends to create a random folding or lay down of the yarn being textured. As described, when one plane vibration is introduced to either the aspirator or the diffuser, a planar crimp will most likely result in the yarn. Alternatively, a random mode of vibration in either of the two elements would produce a random crimp. Still further variation would, for example, result if the diffuser zone were rotated imparting a spiral or corkscrew yarn texture geometry. Thus it can be appreciated that significant variations as to the form and shape of the crimping can be achieved through relative positioning of the outlet nozzle of the aspirator to the diffuser.

The diffuser 45 is provided with a plurality of smallapertures 51 which allow the gas to be separated from the yarn in the diffuser. The holes are of sufficiently small diameter that the yarn cannot be blown into or though them as the gas is separated. Further, the apertures are spaced so that the tube will have sufficient open area to allow all of the gas. to be efficiently separated from the yarn without allowing yarn blowback or escape.

Downstream from the diffuser 45 is a stuffer tube 53 which receives the plug of yarn 49 from the diffuser. The stuffer tube 53 is surrounded adjacent its upstream portion by heater chamber 55. Hot air or gas is circulated through the chamber 55 by inlet line 57 and exit line 59. This serves to set the crimp or folds that have been placed in the yarn in a manner conventional in the art. Alternate to the use of gas, of course, a resistant electric heater or the like could be utilized in this region. The stuffer tube 53 has a smooth and regular inside diameter in order that frictional forces may be uniform along its length. Further, the length of the heater region of the stuffer tube must be sufficient to allow the yarn to be heated to a temperature at which the crimp will set without degrading the polymer material. The heat-setting temperatures are well known in the industry and are utilized in various other crimping processes.

After the yarn has been set, it then moves into a portion 61 of the stuffer tube downstream from the heater region 55, which allows the yarn to cool by letting the heat-above ambient temperature be effectively dissipated. This particular area 61 of the stuffer chamber or tube also serves as a reservoir for accumulated yarn from which a continuous process can take away the material accounting for slight variations in crimp level, without pulling excessive tension in the yarn or moving the reservoir level below the point where it has been adequately cooled. Thus, for example, the reservoir cooling portion 61 can be as long or longer than the portion of the tube subjected to the heating.

When the yarn 13 is first introduced into the diffuser tube 45, a means or mechanism 63 is introduced to momentarily block the exit of the yarn from the diffuser. This can be simply accomplished by merely placing one's hand over the downstream end 63 of the stuffer tube 53, or through the use of a curved pin 65 as shown in the FIGURE. The pin 65 can be attached to a suitable electromechanical apparatus for moving it when desired in a manner conventional in the art, or of course could be moved by hand. All that is required is to introduce some type of blocking means to prevent the highvelocity yarn from blowing freely and under tension through the entire apparatus.

The instant that the yarn begins to fold and slow down, the high-velocity yarn overtaking it will almost instantaneously form a yarn buildup or plug. After the yarn plug has progressed upstream and into the diffuser 45, the diffuser holes 51 begin to become blocked. Once this begins, the means for interrupting the yarn passage can be removed or the yarn winder takeup device can be started. The plug of yarn then further builds up or remains static in the diffuser until the diffuser fills and covers sufficient gas exit holes to cause a back pressure to build up to the point where the plug of yarn yarn plug forward and maintain a self-regulating pressure. The

exiting yarn leaving the device is continuously moved by a winder at a constant or nearly constant speed which is matched to the yarn supply speed entering the crimping apparatus. Alternatively, the pin 65 could be selectively controlled to partially block removal and thus serve to speed up or slow down the process. Such a device is quite conventional in the art and is thus not described herein nor forms part of the inventive concept.

The process can utilize a fixed relationship between the yarn input and output speeds from the apparatus, with the output speed always being slower. The reason for this is that the texturizing and bending of the yarn reduces its length from 10 to 50 percent depending upon the process parameters. Naturally, the shortening of the yarn is affected by the tension that is pulled on it between its exit from the device of the invention and the windup package. The inventory of the yarn in the yarn plug is thus self-compensating, both at its point of impingement and the point of removal. The air pressure affects the position of the plug in the diffuser and the yarn removal tension affects the end of the yarn plug inventory. Various commercially available means are available for so affecting the tension between the device of the invention and the windup apparatus. These include, for example, friction discs, sn ubber pins, slub catchers, and the like, all well known and utilized.

It shouldbe noted that all of the diffuser holes 51 in the diffuser 45 are never covered by yarn. In fact, the yarn removal from the entire apparatus must begin before this happens. Otherwise, the diffuser will no longer separate the gas from the yarn and blockage of the aspirator zone 29 would occur, resulting in a shutdown of the process due to plugging.

As shown in the FIGURE, the diameter of the diffuser 45 and the diameter of the heater zone or stuffer chamber 53 can be the same. However, it may be necessary for some of the yarns having high coefficients of friction to make the stuffer chamber or tube 53 slightly larger in diameter than the diffuser 45. Additionally, it might be necessary to outwardly taper the stuffer tube towards its downstream end 63 to a larger diameter. For example,from,l to 5 of divergence in the stuffer tube can serve to reduce the flow of the yarn plug through the apparatus.

In the aforegoing description, air or similar gas is referred to as entering inlet line 25 serving to propel and initially pull the yarn into the device through the aspirator section 29. A further advantage of this invention is that the gas temperature can be controlled. Thus, by raising the gas temperature one can preheat the yarn and control and alter its modulus of elasticity. This causes the yarn to fill differently as it is packed into the diffuser tube. As a result, not only warm air can be utilized, but steam and the like to serve the aforegoing function of heating the yarn while serving to propel it.

Another variation of the device of the invention could have the exit nozzle portion 43 of the aspirator 29 as a movable rotatable element which could be controlled to rotate or move causing a swirling of the exiting yarn. As a result, the impact of the yarn in the diffuser tube could be effectively varied in a multitude of patterns.

Thus, it can be seen from the aforegoing description that an essentially nonmechanical device and resulting process has been disclosed for the crimping of yarn. The utilization of rotary elements to feed the yarn into the crimping box in the prior art results in various problems as indicated. One problem particularly is that it effectively limits the speed at which the yarn can be processed. The concept of this invention is not in any way limited in processing speeds, since the time and temperature requirements in the heating zone can be achieved merely by making a relatively short zone longerv The aspirator, for example, can transport yarn into the diffuser at speeds as high as 5,000 yards per minute. This speed is generally considerably in excess of that available in other types of apparatus.

I claim:

l. A device for crimping yarn comprising:

a gas actuated aspirator,

means for directing said yarn to an upstream end of said aspirator,

means downstream from said aspirator for forming a yarn plug and crimping said yarn therein and,

means cooperating with said aspirator for selectively controlling the point at which the yarn leaving the aspirator impinges upon said yarn plug to vary the type of crimp put into the yarn.

2. The device of claim I further comprising:

means for heat-setting the crimped yarn.

3. The device of claim 1 wherein said gas actuated aspirator comprises:

a generally tubular section,

and means for allowing pressurized gas to enter an upstream end of said section and exit a downstream end together with said yarn.

4. The device ofclaim 3 further comprising:

an inlet convergent nozzle formed at the upstream end of said tubular section,- said gas entering said section through said nozzle. 7

5. The device of claim 4 wherein said means for directing said yarn to said aspirator comprises:

a hollow tubular member having an inlet upstream end through which the yarn enters and a downstream exit end,

said exit end cooperating with the inlet of said aspirator to form said inlet convergent nozzle.

6. The device ofclaim 4 further comprising:

an exit divergent nozzle formed in said tubular section.

7. The device of claim 2 wherein said means for heat-setting comprises:

a hollow tubular member disposed downstream from said receiving and crimping means,

a heating means surrounding an upstream portion of said tubular member, the remaining downstream portion being of sufficient length to allow the heated yarn to cool.

8. The device of claim 3 wherein said means for forming said plug and crimping said yarn comprises:

a hollow tubular section having a plurality of apertures in the walls thereof.

'9. The device of claim 8 wherein said plug-forming and crimping means is disposed immediately adjacent the exit nozzle of said aspirator.

10. A method of crimping yarn comprising:

directing said yarn to a gas-actuated aspirator,

feeding pressurized gas through said aspirator whereby said yarn is pulled therethrough by the aspirating efi'ect,

selectively folding said yarn into a yarn plug formation to vary the type of crimp formed in the yarn, and crimping said yarn while in said plug formation.

11. The method of claim 10 further comprising:

separating the gas leaving the aspirator from the yarn simultaneously with the crimping thereof.

12. The method of claim 11 further comprising:

controlling the separation of said gas from said yarn to allow a pressure buildup within the crimped yarn plug.

13. The method of claim 10 further comprising:

heating said yarn plug to set the crimp therein, and cooling said heated yarn

Claims

2. The device of claim 1 further comprising: means for heat-setting the crimped yarn.
3. The device of claim 1 wherein said gas actuated aspirator comprises: a generally tubular section, and means for allowing pressurized gas to enter an upstream end of said section and exit a downstream end together with said yarn.
4. The device of claim 3 further comprising: an inlet convergent nozzle formed at the upstream end of said tubular section, said gas entering said section through said nozzle.
5. The device of claim 4 wherein said means for directing said yarn to said aspirator comprises: a hollow tubular member having an inlet upstream end through which the yarn enters and a downstream exit end, said exit end cooperating with the inlet of said aspirator to form said inlet convergent nozzle.
6. The device of claim 4 further comprising: an exit divergent nozzle formed in said tubular section.
7. The device of claim 2 wherein said means for heat-setting comprises: a hollow tubular member disposed downstream from said receiving and crimping means, a heating means surrounding an upstream portion of said tubular member, the remaining downstream portion being of sufficient length to allow the heated yarn to cool.
8. The device of claim 3 wherein said means for forming said plug and crimping said yarn comprises: a hollow tubular section having a plurality of apertures in the walls thereof.
9. The device of claim 8 wherein said plug-forming and crimping means is disposed immediately adjacent the exit nozzle of said aspirator.
10. A method of crimping yarn comprising: directing said yarn to a gas-actuated aspirator, feeding pressurized gas through said aspirator whereby said yarn is pulled therethrough by the aspirating effect, selectively folding said yarn into a yarn plug formation to vary the type of crimp formed in the yarn, and crimping said yarn while in said plug formation.
11. The method of claim 10 further comprising: separating the gas leaving the aspirator from the yarn simultaneously with the crimping thereof.
12. The method of claim 11 further comprising: controlling the separation of said gas from said yarn to allow a pressure buildup within the crimped yarn plug.
13. The method of claim 10 further comprising: heating said yarn plug to set the crimp therein, and cooling said heated yarn.