US3742695A

US3742695A - Thermoplastic yarn plasticizing device and method of plasticizing thermoplastic yarn

Info

Publication number: US3742695A
Application number: US00862097A
Authority: US
Inventors: R Conrad
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-06-25
Filing date: 1969-06-25
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03

Abstract

A yarn heater constructed so that when used with a false twist device, a coaction between heater and spindle is created when plasticizing fluid is caused to spin within the heater in the direction in which the false twist device is inserting twist in the yarn.

Description

United States Patent 1191 Conrad July 3, 1973 [54] THERMOPLASTIC YARN PLASTICIZING 3,031,770 5/1962 Caithens, Jr. et a1. 28/62 UX DEVICE AND METHOD OF PLASTICIZING 3.206.922 9/1965 Nagahara et al 57/34 X 1 3,217.482 11/1965 Baer 28/l.3 X THERMOPLASTIC YARN 3,303,546 2/1967 A Van Blerk.... 28/l.3 [76] Inventor: Robert F. Conrad, 5341 Falmouth 3,340,684 9/1967 Shichman 57/34 Road, Washington, D.C. 20016 3,380,242 4/1968 Richmond et a1. 57/157 X [22] Filed: June 25, 1969 I App] 862,097 Primary Examiner-Stanley N. Gilreath Related US. Application Data Division of Ser. No 656,223, July 26, 1967, abandoned.

US. Cl. 57/l57 TS, 28/62, 57/34 HS 1m. (:1 D02g 1/02 References Cited UNITED STATES PATENTS 11/1959 Bley 57 34 X Assistant Examiner-Werner H. Schroeder Attorney-Shaffert and Miller 1 1 ABSTRACT A yarn heater constructed so that when used with a false twist device, a coaction between heater and spindle is created when plasticizing fluid is caused to spin within the heater in the direction in which the false twist device is inserting twist in the yarn.

3 Claims, 9 Drawing Figures mmmm ms 3.742.695 v sum 2 or z v INVENTOI Rolelf F. (M86 THERMOPLASTIC YARN PLASTICIZING DEVICE AND METHOD OF PLASTICIZING THERMOPLASTIC YARN This is a division of application Ser. No. 656,223, filed July 26, 1967, now abandoned.

This invention relates inter alia to a thermoplastic yarn plasticizing device, hereafter referred to simply as heater, wherein thermoplastic yarn may be subjected to the action of plasticizing fluid such as steam or hot air at elevated pressures and temperatures, and in amanner which results in increasing the effectiveness of yarn heaters per unit of length. This is accomplished, for example, by providing a heater having a yarn passageway in which at an intermediate location along its length a plasticizing fluid under pressure is introduced. The yarn passageway on either side of this location has a capillary diameter. This diameter is preferably larger than the diameter of the yarn passing through the heater but less than 0.02 inches for yarns of 200 denier or less. The capillary passageways act as seals on either side'of the location at which the plasticizing fluid under pressure is maintained and meter its escape to a degree that it becomes-practical to use steam and hot air at elevated pressures as the plasticizing fluid and yet not seriously interfere with texturing operations such as, for example, the modification of torque stretch yarn into set" yarn. Furthermore the capillary passageways are so small that the plasticizing fluid and yarn passing through are so confined together and moved relatively that an efficient heat transfer is obtained between them. Thus, even though the yarn is subjected to the highly effective action of a plasticizing fluid under pressure, a-comparatively small quantity of heated fluid is discharged into the surrounding atmosphere and yet the yarn is satisfactorily.plasticized because the small quantity of fluid which is-heated is efficiently utilized. The heater also includes means for adding heat energy to the expanding fluid passing through one or both of the capillary seals, so that when desired or needed more heat may be transferred to the yarn. It is also contemplated-that the heater may be insulated to improve its performance and may also have associated with it controls of the kind which regulate the supply of energy to the heater to offset the effect of changes in ambient temperatures (and/or line voltage in the case of electrically energized systems).

The incorporation of a heater as described above into thermoplastic yarn texturing operations such as falsetwisting, heat treating of torque stretch to make set yarns, and other thermal processing, involves novel methods and apparatus which are also described hereinafter. For example, one modification of a heater of the kind dealt with herein is constructed so that when used with a false twist device a novel coaction between heater and spindle is created to thus provide a new type of false twist apparatus and method. Specifically plasticizing fluid flowing along the yarn path within the heater is caused tospin in the direction in which the false twist device is inserting twist in the yarn, thus facilitating the action of the false twist device in inserting twist in the yarn.

It has been recognized since shortly after the introduction of nylon in about I938 that steam, especially saturated steam under pressure has a plasticizing effect upon nylon above that which could be attributed to its temperature alone. This fact was utilized in the first commercial process for making torque stretch yarn which involved as one step the treatment of twisted autoclave. At least a decade earlier it had been, visualized that false-twisting might be used to provide a continuous process for making a type of textured (woollike) yarn (See U.S. Pat. No. 2,089,239 to Whitehead) and efforts were made to adapt such a process for the continuous manufacture of torque stretch yarn (See U.S. Pat. No. 2,790,298 to Kunzle). However, no practical way of using steam under pressure in a falsetwisting process was devised, and the manufacture of torque stretch yarn by a continuous false-twist process did not become a commercial reality until the introduction of the false-twist machine shown in Seem and Stoddard U.S. Pat. Nos. 2,803,108 and 2,803,109 which made use of so-called dry heat and embodied a yarn plasticizing heater which was constructed and controlled to give a performance which became the standard for all commercial false-twist equipment up :to the present time, that is one capable of maintaining the dry heat temperature to within i 1 percent in F. Al-

though it is still generally recognized that steam under pressure, with its dual plasticizing effect, is a preferable medium for plasticizing thermoplastic yarns, all modern false-twist machines nevertheless continue to employ so-called dry heat.

One of the objects of this invention'is to. provide methods and apparatus which make possible the use of steam as a plasticizing medium in continuous false-twist processing of thermoplastic yarn and in the manufacture of set yarn from torque stretch yarn.

Following the advent of the Seem and Stoddard machine various improvements were made in the components of false-twist machines which allowed operation at a rate of yarn through-put up to about l20-l 40 yards per minute. As operating speeds were increased the length of yarn heater was also increased; and in present-day machines a heater length of 3 feet or more is not uncommon. Machines with heaters of this length are awkward to service and operate because of their overall height, or because some machine functions are incorporated into a separate apparatus located nearby to avoid excessive overall height. One of the objects of the present invention is to provide a straight-through heater design which is more effective per unit of length and thus again permits a rational design of yarn processing equipment capable of high speed operation.

FIG. 1 is a vertical sectional view of one form of heater according to the invention;

FIG. 2 is a greatly enlarged detail of a modification of a capillary seal for use in the heater wherein the yarn passing therethrough is twisting, as for example in a false twisting operation;

FIG. 3 is a schematic diagram of a false twisting machine which includes a heater system according to the invention;

FIG. 4 is a vertical cross sectional view through a fonn of device useful for heating one or both of the capillary seals of a heater;

FIG. 5 is a schematic drawing showing a heater system according to the present invention incorporated into a machine for manufacturing a set yarn froma torque stretch yarn;

FIG. 6 diagrammatically illustrates another heater system according to the invention suitable for incorporation into a machine for processing thermoplastic textile yarns;

FIG. 7 is a detailed cross sectional view of one position'in the heater system illustrated in FIG. 6;

FIG. 8 is a different kind of improved heater; and

FIG. 9 is a schematic drawing ofa new type of combination machine made possible by the use of heaters according to the invention.

The heater illustrated in FIG. 1 comprises a small metal case 10 having an interior cavity 11. A pipe 12 is threaded into an opening in the side of the case 10 which communicates with the cavity 11 and it is through this pipe so connected that plasticizing fluid under pressure is introduced and maintained in the cavity 11. The top and bottom of the case 10 is provided with axially aligned holes also opening into the cavity 11.

Capillary seals

13 and 14 are secured to these holes. The seals consist of capillary tubes having a very small (capillary) bore as compared to their length. In general, in processing textile yarns of IS to 200 denier, the internal diameter of each of the

seals

13, 14 should not exceed one-fiftieth inch and preferably each seal .should have a length of at least about 500 times its internal diameter although this factor may be diminished as the internal diameter is reduced. The lower limit of internal diameter of the

seals

13, 14 is preferably about twice the diameter of the yarn being processed although diameters but two to four thousandths of an inch larger than that of the yarn may be used. The effectiveness of the seal is not made to depend entirely on the diameter of the yarn passing therethrough being great enough to substantially occupy the whole of the cross sectional area of the seals, and therefore a small denier yarn (say 70) can be economically processed in a heater in which the internal diameter of the seals is sufficient to accommodate a large diameter (say I00) textile yarn, although of course the efficiency of the heater increases as the diameters of the seals are decreased. For this reason it is desirable that the

seals

13, 14 be readily removable so that seals may be replaced as necessary and so that seals of different internal diameters may be used for processing yarns of different denier under optimum conditions.

The cross sectional area of the pipe 12 which introduces plasticizing fluid under pressure into the cavity 11 is preferably larger in cross sectional area than the combined cross sectional areas of the

seals

13 and 14 so that the maintenance of the plasticizing fluid under pressure within the cavity 1 1 does not create undue turbulence within the cavity. It is also a preferable construction to flare the openings at either end of the capillary seals so that the yarn passing therethrough does not strike against sharp edges. FIG. 1 illustrates a heating element 15 associated with the capillary seal 13 in such manner that heat energy may be applied to the seal 13 and thus to the plasticizing fluid and yarn passing therethrough. A similar heating element can, if desired, be employed also in connection with the capillary seal 14 as shown in FIG. 1.

.The plasticizing fluid, which may be air, superheated steam or saturated steam, is, at a minimum, maintained in the cavity 11 under sufficient pressure so that the fluid is forced out the distal ends of both seals. Preferably, when hot air is used, it is maintained in the cavity under a pressure of at least 50 to I00 pounds per square inch. The temperature of the air should, of course, be sufficiently high to accomplish the purposes of the heat treatment. In the case of false twisting of nylon, for example, the temperature of the air is at least above the second order transition temperature and ranges up to about 465 F.

The present invention makes it feasible to employ saturated steam as the plasticizing fluid and because of its dual plasticizing action, the pressure under which the steam is maintained in the cavity 11 need not be so high as to produce a temperature equal to that which would be employed when using hot air as the plasticizing fluid. In general, a temperature about 50 F. below the suitable hot air temperature will produce comparable results.

The plasticizing action of the heater may be further enhanced and regulated by applying heat energy to the capillary seals as by means of a heat element 15. When saturated steam under pressure is employed as a plasticizing fluid the heating element 15 may be adjusted so as to superheat the steam which is passing outwardly through the seals. When hot air is employed the heating element will serve to maintain the air at elevated temperatures, or to raise its temperature, as it expands and passes outwardly through the seals. This effect is also achieved when superheated steam is employed as the plasticizing medium. The heater is preferably enclosed in insulation 16.

FIG. 2 illustrates one way in which the interior walls of the capillary seals may be modified when it is desired to use the heater in connection with a processing operation in which the yarn is twisting as it passes through the heater as for example in a false-twist operation. The interior walls are provided, in the form illustrated, with lands 17 similar in form and purpose to rifling in a gun barrel. This contouring of the inner walls is such that it causes the plasticizing fluid passing through the seals to spin in the direction in which the yarn is twisting or in which it is desired to have it twist.

FIG. 3 is a schematic illustration of the use of a heater as illustrated in FIG. 1, and modified as illustrated in FIG. 2, in a false twisting machine. Yarn Y is passed from a supply 18 through tension controlling rollers 19 and then through the heater H, the false twisting spindle 20, tension controlling rollers 21 to the windup means 22. The manner of operation of a machine so arranged is well known to those skilled in the art and no elaboration of its is required here. The heating system illustrated in FIG. 3 comprises a source of plasticizing fluid under pressure 23 which may be compressed air or a suitable generator of saturated steam under pressure, or of superheated steam under pressure. This source is connected to a supply pipe 24 which extends the length of the machine with which the heater system is to be used. A suitable pressure control valve 25 and stop valve 26 may be included in the system. The pipe 12 of each heater is connected into the supply line 24. A stop valve 27 may be inserted in each pipe 12 in order to cut off the flow of plasticizing fluid to a particular heater. Also, each pipe 12 may be provided with a heating element 28 so as to add heat energy to the plasticizing fluid incoming to the heater H.

The

heating elements

28 and 15 may be supplied from- FIG. 5 is a diagrammatic illustration of a heater syswith a machine for making set yarn from torque stretch yarn. Yarn from a supply of torque stretch yarn 29 is passed downwardly through tension controlling rolls 30 through the heater H and tension controlling rolls 31 to a takeup package 32. In this instance, the interior walls of the seals need not be rifled or contoured as exemplified in FIG. 2.

A further form of heater system is shown in FIG. 6, and the details of one of its positions in FIG. 7. In lieu of employing the case and the pipe 12 leading thereto, the capillary seals 13 and 14 are mounted directly in vertical openings in the supply pipe 24, as may be seen in FIG. 7. Capillary seals 13 and 14 again may have heating elements such as 15 associated therewith as well as insulation 16 as described earlier with reference to FIG. 1. Here again the seals are preferably removable.

FIG'. 4 illustrates another form of heating element which may be associated with the capillary seals 13, 14. This device consists of a block of metal 33 which closely encompasses the outside walls of the capillary seal with which it is associatedand which is capable of serving as a heat sink. Aluminum, for example, is satisfactory in this respect. The block is heated to the desired temperature by means of a cal-rod 34, and the block may also have embedded in it a thermostat 35 which serves to regulate the heat energy supplied to the device.

In some operations, satisfactory plasticizing of the yarn may be accomplished by simply energizing and controlling the supply of heat energy to the heating devices (15 or 33) surrounding the capillary seals 13, 14, thus providing a heater consisting of the capillary tubes of the dimensions described and means for heating them. The heating of the yarn achieved is highly efficient since the diameter of the tubes is such that no appreciable chimney effect exists and, as compared with presently known heaters, a large proportion of the air which is heated is in effective heat-exchange relationship with the yarn passing through the seals. A heater of this kind is obtained, for example, by closing off the stop valve 26 to a heater H as illustrated in FIG. 3, cutting off the supply of energy to the heating element 27 and energizing only the heating elements 15 associated with the capillary seals 13, 14. Such a simplified heater may be specially constructed, as shown in FIG. 8, by simply wrapping a heating element such as 15 around a capillary tube having an inner diameter of one sixtyfourth inch and a length of 12 inches and enclosing the whole in insulation such as 16. Such a heater will produce results comparable or superior to those obtained by presently knownyarn heaters which are of twice the length and consume greater quantities of energy.

It is apparent that the rate at which the yarn is traveling through any heater and the length of the heater have a bearing on the temperature to which the yarn is heated. In present-day false-twist machines for example wherein the through-put of yarn may be at the rate of 120-140 yards per minute, the heaters are three feet or more in length. Such heater dimensions have necessitated special designs, including elevated working platform in some cases, so that the operative may properly oversee and service the machine. A heater made according to FIG. 1, for example, but with the capillary seals 13, 14 lengthened to 8 inches each (the overall length of the heater then being about 17 inches) will produce results at least comparable to those attained with present day heaters which are three feet or more in length. Furthermore, the exemplary heater also permits the economical use of saturated steam under pressure as the plasticizing medium with further attendant advantages.

The efficiency of the heater is such that it is now possible to design a machine which combines the making of false-twist yarn at the rate of 120-140 yards per minute and the post-treating of it to make a set yarn'in a straight run (preferably downwardly) and within the overall height of present-day machines designed merely to produce false-twist yarn alone at the stated rate. Such a combination machine is illustrated diagrammatically in FIG. 9. It is enlightening with respect to the utility of the present invention to compare the simplicity and efficiency of this design with the awkward arrangements which heretofore have been suggested and in some cases commercially produced as combined false twisting and post treating machines. In FIG. 9, 33 represents a supply of thermoplastic yarn such as denier 34 filament nylon. The yarn passes from the supply downwardly around the tension controlling rolis 34 through the heater 11,, the false twisting spindle 35 and the tension controlling rollers 36. The relative speeds of the

rollers

34, 36 are adjusted to provide an overfeed of 3 percent. The heater H is constructed in accordance with FIG. 1 as modified according to FIG. 2. The internal diameter of the capillary seals of the heater I-l is 0.01 inch and each seal is 8 inches in length. The yarn passes from the rollers 36 through the heater H and then to the tension controlling rolls 37 and then to the windup means 38. The speed of the rollers 37 relative to the rollers 36 is such that the yarn is overfed to the heater H, by 10 percent. The heater H is of the same construction as the heater H except that the internal walls of the seals are smooth, and the seals are 0.015 inches in diameter, being made larger than those of heater H, to accommodate the larger diameter of the partially relaxed crimped yarn and thus avoid an undesired accumulation of yarn. The source of plasticizing fluid 23 is a steam generator which delivers saturated steam at pounds gauge pressure (about 330 F.) to the heaters H, and H The energy supplied through the heating elements 15 in each of the heaters is adjusted so that the steam expanding in the capillary seals is superheated. The yarn is traveled downwardly from the supply so that greatly improved control of it is obtained as it is overfed to the heater H What I claim is:

1. A method of false twisting thermoplastic yarn plasticizing fluid is introduced into said tube at a location and under sufficient pressure to exit said tube from both ends of said tube.

3. The method of claim 2 including the step of providing additional heat to said plasticizing fluid within said tube.

Claims

2. The method of claim 1 wherein said pre-heated plasticizing fluid is introduced into said tube at a location and under sufficient pressure to exit said tube from both ends of said tube.
3. The method of claim 2 including the step of providing additional heat to said plasticizing fluid within said tube.