US2874410A

US2874410A - Apparatus for uniformly drawing a plurality of filaments

Info

Publication number: US2874410A
Application number: US440501A
Authority: US
Inventors: Kinney George Allison
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1954-06-30
Filing date: 1954-06-30
Publication date: 1959-02-24
Anticipated expiration: 1976-02-24
Also published as: GB796019A; DE1171107B; FR1133962A; NL96257C

Description

1959 G. A. KINNEY ,874,410

APPARATUS FOR UNIFORMLY DRAWING A PLURALITY OF FILAMENTS Filed June 30, 1954 INVENTOR GEORGE A. KINNEY BY 6* W ATTORNEY Un d States Patent APPARATUS FOR UNIFORMLY DRAWING A PLURALITY F FILAMENTS George Allison Kinney, Glen Mills, Pa.,'assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Application June 30, 1954, Serial No. 440,501

6 Claims. (Cl. 18-8) Thisinvention is concerned with apparatus for drawing or stretching shaped articles,.such as yarn, ribbons and the like at elevated temperatures, and more particularly with draw or snubbing'pins, which can be held close to a desired temperature.

, In the production of shaped articles, such as artificial yarn, it is common practice in the textile industry to stretch the yarn to increase its tenacity. U. S. Patent 2,289,232 discloses the use of a snubbing pin to localize the drawing stresses. Such pins are particularly desirable when drawing fibers prepared from linear condensation polymers, such as the polyamides, polyesters, polyethers, polyanhydrides and polyacetals such as described in U. S. Patent 2,071,251. In many cases it is necessary to heat the draw pin to obtain optimum yarn processing conditions.

In the manufacture of a product having a wide range of utility in the textile field, it is important that uniform physical properties be obtained. With reference to yarns of linear condensation polymers, it has been found that variations in the drawing process are reflected criticallyin certain yarn properties. Apparently this resultsfrom the fact that the crystallite orientation along the fiber axis, as shown by X-ray examination, is a function of the draw ratio of the yarn. For example, the affinity of these fibers for dye-stuffs decreasesmarkedly with increasing orientation. In some cases, a change of about 3-4 C. in the temperature of the draw pin, other conditions remaining constant, will result 'in a perceptible difference in dyeability. For this reason it is very desirable to use a draw pin which will vary no more than about 1 C. from the; selected operating temperature. Unfortunately, it is eco-' nomically undesirable to employ the large number of control devices required to provide individual temperature controls for each pin.

The use of a manifold vapor heated draw pin system is desired for economy, but difficulties arise, such as in keeping the temperatures of the pins uniform because of un controllable accumulation of condensed liquid or of non condensable gases within thehollow pins. The accumulation of condensed liquid cools the pin, while the stagnation of noncondensable gases accomplishes the same result by preventing an adequate supply of vapor from reaching the pin. The tendency of liquids and gases to accumulate in the pins is aggravated by the usual positioning of the pins inclined from the horizontal to minimize any tendency of the yarn to tangle at the pins; for convenience in string-up, the pins are preferably sloped downward.

An object of this invention is to provide apparatus having a plurality of vapor-heated, hollow draw pins readily controllable within close temperature limits at'any desired temperature. More specifically, theinvention has as an object the provision of a manifold unit in which both the condensed fluids and the noncondensable gases are removed efiiciently from the draw pins and replaced by the 2,374,410 Patented Feb. 24,1959

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' to build and easy to maintain in operation. Additional objects are apparent hereafter.

The above objects are accomplished by the present invention which, briefly described, comprises a sealed manifold unit in which a plurality of hollow draw pins are integrally attached to a boiler. The hollowed-out portion of each draw pin is substantially conical in shape, providing'for the continuous downward flow of condensed liquid back into the boiler and the continuous upward displace? ment of noncondensable gases into the upper section of the boiler. Accumulated noncondensable gases are easily vented by opening valves at the top of the boiler while the heating medium continues to boil. The apparatus of this invention thus serves to heat shaped articles, such as filaments, rods, tubing, ribbons and yarns which are traveling from one place to another and provides a way to localize heat and stress on these articles to permit uniform drawing. The apparatus comprises a' sealed unit, such as a boiler, containing heating media and means, and having a lateral outlet to which is attached, either directly or indirectly, a pin, usually cylindrical, which has an internal, hollow, tapered portion, the wide taper of which is at the end of the pin nearest the unit, the bottom taper sloping in a downward direction'toward the bottom portion of the unit and the upper taper sloping in an upward direction toward the upper section of the unit. If the pin is connected to the unit or boiler through a third passageway, the member containing that passageway is generally similarly tapered internally and the tapered edges are cooperatively aligned with those of the pin. Optionally, the

' entire apparatus or any portion of it may be bafiled to promote the continuous flow of vapor through the draw pin and to isolate the noncondensable gases in the upper section of the boiler.

The invention will be more fully understood from the following description and the accompanying drawings, in which:

' Figure 1 is a view in front elevation of a bank of draw 7 pins, in which the view of the draw pin at the right is taken on A-A of Figure 2 and a portion of the entire front of the right side of the unit is cut away to show detail;

Figure 2 is a cross-sectional view taken on the line 22 of Figure l;

Figure 3 shows a cross-sectional view of an alternain Figure 2, are provided at intervals in the upper portion of the boiler, and hollow substantially cyclindrical members or blocks 4 are sealed to the boiler at each-opening.

The hollow channel 5, shown in Figure 2, in each block is tapered, the widest section corresponding in cross-section to the opening 3 in the boiler. Near the end of the block a drilling 8 is made substantially at right angles to and meeting channel 5, and at this location, a trollow cylindrical draw pin 6 is mounted, preferably at right angles to the block and in a downward direction. The hollow portion 7 of the draw pin is also tapered, having substantially th'e shape of acon'e or truncated cone, and is connected to the tapered channel 5 in the block by opening 8 in the side of the block. While the pin may be used in a horizontal position, the downward slope of the pin shown in Figure l assures that successive turns of the yarn 9 wrapped about the draw pin will remain separated; .preferably thQ draw Pini? ,l i hlgl "i 35F,-

about 3' from the horizontal. The hollow portion 7 of thedraw pin is tapered sufficiently to overcome the reverse tilt of the pin and provide a downward slope from the end of the pin towards the manifold of at least about 1- from the horizontal. Accordingly, vapor: from the heating medium 10 in' the' boiler condenses irr thel draw pin and drains from the pin at the bottom 33 through opening 8 into channel in' the block and down theslope 34 of the block back into the boiler. At the same" time, the continuous flow of vapor to the pin displaces non? condensable gases which may be present in the pin upwards from the pin beingdirected by surface 35,. through the tapered channel in the block, being directed. by surface 36, and into the upper section of the" boiler for. removal at vent 14..

With a boiler in the horizontal position, horizontal tubes .11 are provided to run the entire length of the boiler near the bottom of the vessel and open to. the outside at each end. Suitable rod-shaped electrical heati'ngfelemcnts 12 are utilized to provide uniform heating throughout the boiler.' Preferably twoheating elements are used, one of which is designed to operate continuously and provide about 60-85% of the heat required, while the other is operated by suitable controls to supply heat as required to maintain the unit at the desired temperature. A well 13' is. provided. at one end of the boiler in the upper part of the vessel for a temperature controller to be used in conjunction with the heating elements. Temperature controllers having the required sensitivity to maintain the unit within 1 C. of the desired temperature are commercially available and methods of their use are well-known in the. art. The boiler need not be horizontal, for operation on an inclined plane or in the vertical is possible. Since the horizontal positioning provides for uniform heating of the blocks and pins with a minimum of control, the horizontal positioning is preferred.

At each end of the boiler a vent 14 is provided. By the use of suitable valves (not shown) the vents can be closed to seal the apparatus during operation or opened to vent the noncondensable gases. The vents, automatic or hand-operated are usually used to charge the vessel with heating fluid which may be almostany liquid which has a sufficiently high vapor pressure at the operating temperature. Freon 113" (trichlorotrifluoroethane) is very desirable because it causes little or no corrosion. Freon 113 is also advantageous in that its heavy vapors aid the displacement of noncondensable gases (usually air) to the top of the boiler. The amount of heating fluid charged to the vessel is not critical; however, the liquid level should be high enough to cover the tubes containing the heating elements to avoid superheating the vapor, but the level should not be so high that. flooding of the draw pins occurs.

The apparatus may be constructed from steel or other common materials; however, it is preferred that the draw pins and temperature control well be fabricated of copper to obtain high sensitivity towards the transfer of heat. The unit should be sealed air-tight by usual techniques and covered with insulation, except for the draw pins or the active sections thereof, to obtain optimum results. Usually it will be desirable to cover the draw pins with thin. sleeves of ceramic material. to decrease abrasion of the pins by the yarn. Al'simagfi a bonded titanium dioxide, is excellent material for this purpose. Although the apparatus may vary in. size, it will usually be designed to provide draw pins having diameters in the range of about. 0.25 inch to about 2.5. inches. At' high yarn speeds pins of even greater diameter may be used.

Operation of the unit is begun by charging the boiler with an excess of the liquid heating medium at regular atmospheric pressure, closing the valves at the vents and refluxing the heating medium at a temperature somewhat higher than the desired operating temperature.

4. The unit is then vented by quickly opening and closing the vents at each" end of the vessel several times, leaving Example A bank. containing 6 draw pins was constructed in accordance with the preceding description, using 2.5" steel pipe for the boiler. The remaihder of the unit was also constructed of steel with the exception of the draw pins and temperature control well which were made of copper. The apparatus was covered with a2" layer of asbestos insulation except. for the draw pins,v

which were covered with Alsimag sleeves. Two rodtype electrical heating elements and a temperature con: troller of the pressure bulb type equipped with a micro switch were obtained from commercial sources; one heating element was set to operate full time and the other was set to operate at the demand of the temperature controller. The boiler was charged with Freon 113; this was heated to 135 C.; and the boiler was vented by quickly opening and closing the valves thre times at each end in alternation. The temperature of the boiler was then dropped to about 99 C., and. the temperature of the draw pins was measured with calibrated thermocouples and a reliable potentiometen The temperature showed a slight cyclic change within the limits 99.5 C. maximum and 985 C. minimum, the maximum pin-to-pin difference at any time being 0.3 C. After 24 hours of continuous operation the temperature limits were 98.4 C.99 .5 C. with a maximum pin-topin difference of 035 C.

In the previously described embodiment of the invention the removal of the noncondensable gases from the pin depends on the constant how of fresh vapor into the pin and the convenient escape path for the noncon densable gases through the tapered channel. While this design is effective, noncondensable gases can become mix-ed to some extent with condensable vapors .through turbulence andtherefore recirculate through the pin. This is not undesirable when the amount of noncondensable gas present in the vessel is low, which will be the normal case; as pointed out above, the unit may be vented occasionally to void the unit of noncondensable gases. However, when a large number of units are in use, it may happen that some units are not vented over a long period of time and that an appreciable concentration of noncondensables builds upin some manner. For example, it is known that when water is used as a heating medium there may be a slow reaction with metallic elements in the apparatus with the evolution of hydrogen. Units of the above design in which noncondensable gases have been allowed to accumulate to levels far exceeding nor mal may therefore be found to have lower pin temperatures than other units which, for example, have been freshly vented. Accordingly, in one preferred embodiment of. this invention described below, bafhes are provided tov insure that noncondensable gases are forced from the pin andtrapped in the space in the upper part or the boiler.

Referring now to Figures 3 and 4, a cylindrical block 15 isv sealed to. the upper part of the hat side of an elongated boiler 16 of semi-circular cross-section. Two

tapered channels

17 and 18 are bored in the block such that the lower part 37 of lower channel 17 slopes down- .ward approaching the boiler. and the upper part 38' of upper channel 18 slopes upward. towards the upper section of the boiler, and strip 39 forms part of the baffle arrangement, this strip being the section remaining in the block between the drilled channels or being an added, wedge-fitted or dove-tailed str p. Access into the boiler for the two channels is afforded by openings 19 and 20 in the side of the boiler, leaving strip 40, similar to strip 39, to form part of the battle system. A hollow cylindrical draw pin 21 shown in Figure 4 is embedded in the side of the block near the end of the block. The hollow portion 22 of the draw pin has substantially the shape of a cone or truncated cone and is connected to the two channels in the block by opening 23 cut into the side of the block. Battle 24 is affixed to the block between

channels

17 and 18, being aligned with strip 39 divides opening 23 into an upper and lower channel 231 and 232, and extends into the hollow portion of the draw pin for a considerable distance, as shown in Figure 4. Bafile 24 can be conveniently wedge fitted between the end of strip 39 and the opposite edge 41 in block 15. The baffles can, if desired, be tapered, preferably paralleling the walls opposite them. As before, the draw pin is mounted at a downward slope of at least 3, the taper of the hollow portion of the pin being at least 1 greater than the slope of the pin to allow drainage.

The boiler is divided into two sections by curved baflle 25 running the entire length of the boiler. One edge of the baffle is affixed to the flat side of the boiler between the openings 19 and 20, while the other edge of the bafiie is attached at a point 26 near the bottom of the curved side of the boiler considerably below the liquid level of the heating fluid 27. Openings 28 in the baffle below the liquid level allow the liquid on each side of the baffle to attain a common level; as an alternative the openings 28 may be omitted if the lower edge of the bafile is not sealed to the. lower part of the boiler wall, leaving a small gap at 26. The unit is also provided with vents 29, tubes 30 for heating elements 31, and a Well 32 for a temperature controller attached at one end of the unit beneath the bafile.

.In the preferred embodiment of the invention described above, noncondensable gases are forced into the upper section of the boiler where they are effectively trapped. Since the upper section of the boiler receives heat from the lower section only indirectly, condensation of vapor occurs in the upper section, causing a continuous gentle flow of vapor from the lower section of the boiler through channels 17 and 232, into the hollow pin, and through

channels

231 and 18 into the upper section of the boiler. If desired, the velocity of flow through the unit may be increased by using less insulation over the upper part of the boiler than elsewhere on the unit, thus increasing the heat loss from the upper part of the boiler and promoting condensation of vapor. Since noncondensable gases are unable to mix with fresh condensable vapor and return to the pin, it is possible to allow them to accumulate for a long period of time before venting of the unit is required. In another embodiment of this invcntion the hollow pins are attached directly to a boiler of any desired shape. The dimensions of the pin, such as its length, are such to provide easy access to the pin by the operator and usually the insulation about the boiler insulates a small portion of the pin. The tapered section inside the pin and the mounting of the pin are fixed so that ready flow of liquid downward and of noncondensable gas upward is effected. If desired the pin and boiler may be equipped with baflles as in the preferred embodiment described above.

The apparatus of this invention is self-contained and occupies relatively little space. It is particularly adapted to be used with industrial draw twisting and draw-winding equipment, e. g. of the type disclosed in U. S. Patent 2,474,912. The units areeasily insulated and heat losses can be maintained at a very low level. The apparatus may be made long enough to supply pins for any desired 6 number of drawing positions. In industrial practice, banks containing at least twelve pins will usually be employed, while for ease of maintenance the unit will usually not contain more than about 30 or 40 pins.

Any departure from the above description which conforms to the present invention is intended to be included within the scope of the claims.

I claim:

1. Apparatus for drawing shaped articles at an elevated temperature comprising a sealed boiler containing a vaporizab'le liquid heating medium and having a plurality of lateral outlets above the liquid level of the heating medium; heating means adapted to heat the heating medium, the heat output of said heating means being regulatable; a temperature controller adapted to control the heat output from the heating means so as to control the temperature of the heating medium; and fitted to each of said lateral outlets in the boiler a draw pin sloping at an angle of at least 3 from horizontal, said pin having a hollow, concentric tapered portion in communication with the lateral outlet, the wide taper being at the end of the pin nearest the lateral outlet, the bottom taper sloping downward from horizontal towards the boiler at an angle of at least 1 and the upper taper sloping upward from horizontal towards the boiler.

2. Apparatus in accordance with claim 1 wherein said heating means comprises a plurality of electric heating elements with the heat output of at least one of said electric heating elements being regulatable and controlled 7 by said temperature controller.

3. Apparatus in accordance with claim 1 in which said draw pins are cylindrical and have a diameter of 0.25 to 2.5 inches.

4. Apparatus in accordance with claim 1 in which said draw pins'have anabrasion resistant ceramic surface.

5. Apparatus inaccordance with claim 1 in which said draw pins contain a bafile dividing the space within said draw pins into upper and lower zones.

6. Apparatus for drawing shaped articles at an elevated temperature comprising a sealed boiler containing a vaporizable' liquid heating medium and having a plurality of lateral outlets above the liquid level of the heating medium; heating means adapted to heat the heating medium, the heat output of said heating means being regulatable; a temperature controller adapted to control the heat output from the heating means so as to control the temperature of the heating medium; and fitted to each of said lateral outlets in the boiler a draw pin having a hollow, concentric, tapered portion in communication with the lateral outlet, the wide taper being at the end of the pin nearest the lateral outlet, the bottom taper sloping downward from horizontal towards the boiler to drain the condensate from the pin and the upper taper sloping upward from horizontal towards the boiler to remove noncondensables from the pin.

References Cited in the file of this patent UNITED STATES PATENTS 120,479 Babbitt Oct. 31, 1871 1,597,014 Campbell et al Aug. 24, 1926 1,604,397 Ercanbrack Oct. 26, 1926 1,852,252 McIntosh Apr. 5, 1932 2,244,831 Drichta et al June 10, 1941 2,289,232 Babcock July 7, 1942 2,302,792 Moritz Nov. 24, 1942 2,533,013 Hume Dec. 5, 1950 2,561,424 Spieth July 24, 1951 2,569,735 Seligman Oct. 2, 1951 2,730,609 Constantinesco Jan. 10, 1956 FOREIGN PATENTS 25.172 Great Britain Dec. 19, 1899