US3099872A - Method and apparatus for heating and drawing threads - Google Patents

Method and apparatus for heating and drawing threads Download PDF

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Publication number
US3099872A
US3099872A US87480A US8748061A US3099872A US 3099872 A US3099872 A US 3099872A US 87480 A US87480 A US 87480A US 8748061 A US8748061 A US 8748061A US 3099872 A US3099872 A US 3099872A
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Prior art keywords
thread
tube
temperature
heat
heating
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Expired - Lifetime
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US87480A
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English (en)
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Siggel Erhard
Kleekamm Fritz
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Glanzstoff AG
Vereinigte Glanzstoff Fabriken AG
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Glanzstoff AG
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    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02J—FINISHING OR DRESSING OF FILAMENTS, YARNS, THREADS, CORDS, ROPES OR THE LIKE
    • D02J1/00—Modifying the structure or properties resulting from a particular structure; Modifying, retaining, or restoring the physical form or cross-sectional shape, e.g. by use of dies or squeeze rollers
    • D02J1/22—Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch
    • D02J1/224—Selection or control of the temperature during stretching

Definitions

  • FIG. 2 METHOD AND APPARATUS FOR HEATING AND DRAWING THREADS Filed Jan. 10, 1961 FIG. 2
  • the invention is concerned with the improvement of the process in which a synthetic filamentary material having heat-stretchable properties is first heated at a lower drawing temperature under stretching tension and is subsequently heated at a higher fixing temperatur also under stretching tension.
  • the improvement of the present invention is embodied in special apparatus as well as in the process itself.
  • one practice has been to pass the polyamide thread over a first rod, heated to about 70 C., while stretching to about three times the original length of the thread and then over a second rod, heated to about 190 C., with an additional twofold stretching of the thread.
  • the thread is thus drawn or stretched to about 500% of its original length.
  • the two stages are carried out at different temperatures, the first stage being carried out at a temperature referred to as the drawing temperature and the second stage being carried out at a temperature referred to as the fixing or stabilizing temperature.
  • stretching and thermal stabilization of the thread is accomplished with at least two devices, such as rods, rollers, plates or the like, each being maintained at a constant but different temperature.
  • the second or fixing stage is effective only if the ties at thread remains in contact with a heated surface which is sufiiciently large to provide an extended time for heating.
  • the heating time in the second stage is dependent in each case upon the particular synthetic material being treated as well as the drawing speed.
  • the thread must maintain contact with the heated surface in the second stage at least long enough for the thread to reach the particular stabilization or fixing temperature at which the surface is maintained.
  • a principal object of the present invention is to provide a method and apparatus for simultaneous heating and drawing of synthetic threads in a single stage wherein it is also possible to obtain a thermal stabilization of the threads.
  • Another object of the invention is to heat, stretch and stabilize synthetic threads in one continuous operation in which the thread being treated is maintained in constant contact with a heated surface.
  • Still another object of the invention is to provide a relatively simple heating device for stretching and stabilizing threads, said device being readily adapted for combination with the usual feed and draw rolls employed to impart a stretching tension to the threads.
  • Yet another object is to provide a method and apparatus whereby synthetic threads can be heated and drawn to give valuable filamentary products, especially as regards their thermal stability.
  • FIG. 1 is a top plan view and side elevational view, the latter in cross-section, of one heating device which can be employed in conjunction with the invention
  • FIG. 2 is a top plan view and side elevational view, the latter in cross-section, of a second embodiment of a heating device
  • FIG. 3 is a top plan view and side elevational view, the latter in cross-section, of still another and preferred embodiment of the heating device.
  • FIG. 4 is a side elevational view in partly schematic form which illustrates the embodiment of FIG. 3 in combination with the remaining essential elements of heating and drawing apparatus.
  • a resistance heating element is illustrated in schematic form.
  • the heating and drawing of synthetic threads together with their thermal stabilization can be accomplished in a more favorable and improved manner if the thread is simultaneously heated and drawn in spiral winding contact over the surface of an elongated body made up of substantially cylindrical crosssections, the surface being heated at progressively increasing temperatures in the direction of thread travel over the surface.
  • the temperatures of the surface are regulated such that the usual dnawing or stretching temperature is maintained at the run-on or thread receiving end of the heated elongated body and the maximum fixing or stabilizing. temperature is preferably maintained at the run-off or thread discharge end of the elongated body.
  • the thread is thus continuously heated in one stage while being stretched with uninterrupted contact with a single heated surface.
  • the thread run-off end of the elongated body and its corresponding surface can be heated by direct heat exchange to a temperature somewhat below the maximum fixing temperature, it is preferable to employ the highest temperature possible in order to obtain optimum results.
  • the continuous one-stage heating and drawing of the invention can be accomplished by employing a novel combination of apparatus which includes the conventional feed and draw rolls as means to supply the thread and means to draw off the thread at a more rapid rate than it is supplied, thereby imparting a stretching tension to the thread.
  • a special heating device is positioned or mounted, preferably on a frame common to one of said rolls, in the path of the thread as it is being drawn.
  • the heating device is essentially an elongated, heat-conducting tube which is hollow in at least a portion of its length.
  • the tube has a continuous outer sunface in the form of a cylinder, frustum or the like, and an inner axial bore or opening extending from the thread receiving end of the tube toward the thread discharge end, preferably to the point along the axis corresponding to the surface area where the maximum fixing temperature is reached.
  • the axial opening or bore becomes progressively smaller in a direction proceeding from the thread receiving end to the thread discharge and such that the annular cross-sectional wall thickness of the tube diminishes progressively in the opposite direction.
  • FIG. 1 illustrates one heating device constructed in accordance with the invention in which the outer or thread-contacting surface of the tube has a substantially cylindrical shape.
  • FIG. 2 illustrates an alternative embodiment with a substantially frusto-conical shape.
  • An especially preferred elongated tube is illustrated in FIG. 3 and is also shown with the remaining essential apparatus in FIG. 4.
  • the preferred tube has a substantially frusto-conical shape defined by its outer surface at the lower or thread discharge end, tapering away therefrom. At its upper or thread receiving end the tube is outwardly flared to give a hyperbolic surface shape.
  • the thread discharge end of the tube is internally heated by an electrical resistance heating element R.
  • the process of the invention is advantageously carried out in accordance with FIG. 4 wherein the thread T is supplied by the feed rolls 1 and drawn under stretching tension by the draw rolls 2. Heating and stretching of the thread takes place on the surface of the tubular heating device 3 which is mounted in any convenient manner between the feed and draw rolls. It is helpful to provide this heating device with a rotatable elliptical head or rim 4 at the thread receiving end so as to fix the point at which the thread engages or runs on to the tube.
  • the thread then follows a spirally advancing line along the surface of the tube to the thread discharge end, the thread being maintained in continuous and uninterrupted contact with the tube because of the stretching tension imparted by the feed and draw rolls.
  • the length of this contact can of course be varied by the shape of the tube as well as its length and diameter. The number of turns of the thread around the tube can also be varied to provide the desired length of contact. In most cases, one complete turn is satisfactory.
  • the lower or discharge end of the elongated tube 4 is shown to have an axial recess or insert containing an electrical resistance heating element R which is employed to heat this end of the tube on its surface to that temperature required to fix or stabilize the thread, but not higher than the maximum fixing temperature which is dependent upon the particular synthetic material being processed.
  • the tube is preferably constructed of a heat-conducting metal or two or more different metals, thereby conducting heat to the surface of the tube and toward the thread receiving end of the tube. Because of the gradually diminishing cross-sectional area of the annular walls in the upper or hollow portion of the tube, the surface temperature correspondingly becomes lower through heat conduction and radiation in the direction of the unheated thread receiving end. This temperature drop would occur to some extent even with a constant annular wall thickness, but a continuous diminuation of this thickness is necessary to obtain a sufficient temperature gradient over a relatively short distance.
  • any suitable metal can be employed in constructing the tubular heating device such as iron, Bessemer steel, chromium steel, nickel steel and the like. It is especially advantageous for reasons of cost to construct the tube with an inner core of a relatively inexpensive metal such as iron and to use an outer surface layer or mantle of a more expensive but corrosion resistant metal such as chromium steel. Where a very high temperature drop is required over a. relatively short length of the tube, different metals with decreasing coeflicients of heat conductivity can be arranged in longitudinal sections of the tube, e. g. the lower portion being constructed of iron and the upper portion of chromium steel.
  • the tubular bodies illustrated in FIGS. 1-4 are given merely by way of example of the heating device required by the invention. Minor variations in shape and construction can readily be made without departing from the spirit or scope of the invention.
  • the temperature of the tube surface can also be regulated by means of a fluid heat exchange medium, e.g. a gas, vapor, or liquid capable of being maintained at the maximum fixing or stabilizing temperature.
  • the lower or thread discharge end can be provided with a metal block or similar insert containing a continuous fluid passageway for circulation of the heat exchange medium, this passageway being in fluid connection with external inlet and outlet conduits.
  • the tubular device of the invention then acts as a means for indirect heat exchange between the heating fluid and the thread which lies in contact with the outer surface of the tube.
  • the thread discharge end of the tube be heated to the required fixing temperature and that the surface temperature then progressively drop to a suitable drawing temperature at the thread receiving end.
  • the apparatus described above provides an especially useful means for accomplishin this result.
  • one special advantage of the invention is that the thread provides its own uniform and gradual stretching along the surface of the tube in accordance with its degree of plastification or extensibility, the friction of the heated surface and the tension applied by the feed and draw rolls. Optimum results in the textile and physical properties of the thread are thusv obtained, and such results are believed to be caused by the fact that there is no intermittent cooling of the thread between the drawing temperature and the fixing temperature.
  • the apparatus of the invention is especially advantageous in that the tubular heating device can be directly mounted without difficulty on all of the commer cially known stretching or drawing equipment. The very small space requirement of the tubular heating device is an added advantage.
  • thread is employed herein with reference to both monofilaments and bundles of a plurality of filaments in the form of a yarn, tow, cable or the like.
  • drawing is employed with the same meaning as the term stretching.
  • fixing and stabilizing are both employed to refer to the heat treatment of a thread whereby certain thermal properties or characteristics are rendered more stable. Such thermal properties are often different with different synthetic materials even though the processing steps remain substantially identical.
  • the present invention is concerned with drawing and fixing threads by the so-called dry heating method as distinguished from wet heating in a liquid bath or the like.
  • the present invention is further illustrated by the following example in connection with FIG. 4 for the thermal stretching and fixing or stabilizing of polyethylene terephthalate.
  • the invention is not to be limited to this example which is given merely as one preferred embodiment of both the apparatus and process.
  • EXAMPLE A polyethylene thread of 75 denier (36 individual filaments) obtained in a conventional spinning or extruding process is removed from a storage spool or bobbin (not shown) by the pair of clamping feed rolls 1. The thread then runs on the tubular heating device 3 at a point determined by the elliptical head 4 and is entwined or spirally wound on the surface of the tubular body. The draw rolls 2 are operated at a rate of speed four times faster than the feed rolls 1 so as to draw off the thread under tension with stretching to about four times the original length of the thread.
  • the tubular body 3 has an interior core composed of iron and a chromium-plated mantle or outer surface to engage the spirally wound thread.
  • the overall length of the tube is 12 cm. with a minimum outer diameter adjacent the thread receiving end of 51 mm. and a maximum outer diameter at the thread discharge end of 55 mm.
  • the tube is provided with a hollow axial bore which is cylindrical in shape and has a diameter of 45 mm.
  • the maximum wall thickness at the lower or discharge end of the tube is 5 mm., and this thickness decreases progressively to a minimum of about 3 at the upper end.
  • An electrically heated metal block R is inserted into the lower end of the axial bore or opening, and the surface of the tube at this point is heated to 200 C. Because of heat losses, the temperature of the tube surface diminishes upwardly to the thread receiving end, at which point the temperature is 70 C.
  • the thread occupies a linear distance of about 1-4 cm. and its rate of travel, as determined by the draw roll, is about 40 cm./sec.
  • the thread After completion of the thermal stretching and stabilization on the heated tube, the thread has a strength of 5.5 grams/ denier and an elongation of 16%.
  • the thread is especially distinguished by a low heat shrinkage capacity of only 7.2% as measured in boiling water for one hour.
  • Synthetic Range Preferred Range Preferred (appr0x.) (approx) (1) Polyethylene terephthalate -120 136-190 165 (2) Nylon 90-180 180-215 210 (3) Polycaprolactam 20-110 80 160-210 190 (4) Polyacrylorutrrle 100-140 130-180 (5) Polyethylene 60-115 110 100-115 110 The invention is hereby claimed as follows:
  • An improved apparatus for heating and drawing threads which comprises: means to supply thread; means for drawing off said thread at a more rapid rate than the rate at which the thread is supplied by said supply means; and a heating device positioned in the path of said thread between said supply means and said drawing off means, said heating device comprising an at least partially hollow, elongated, heat-conducting tube adapted to receive said thread at one end for thread travel in spiral winding contact along the outer surface of said tube and to discharge said thread at the opposite end, the longitudinal axis of said tube coinciding approximately with the linear direction of said thread path and the annular cross-sectional wall thickness of said tube in the hollow portion thereof diminishing progressively from said discharge end to said receiving end, and means to heat said tube at said discharge end for conductance of heat radially to the outer thread-contacting surface of the tube and longitudinally to said receiving end.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
US87480A 1959-07-04 1961-01-10 Method and apparatus for heating and drawing threads Expired - Lifetime US3099872A (en)

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DEV0016848 1959-07-04

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BE (1) BE592523A (US07816562-20101019-C00012.png)
CH (1) CH383542A (US07816562-20101019-C00012.png)
FR (1) FR1261142A (US07816562-20101019-C00012.png)
GB (1) GB892355A (US07816562-20101019-C00012.png)
NL (1) NL253396A (US07816562-20101019-C00012.png)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3416206A (en) * 1964-03-12 1968-12-17 British Nylon Spinners Ltd Means for localizing tension in running yarn
US4075274A (en) * 1973-04-07 1978-02-21 Teijin Limited Method for drawing and heat-treating polyester yarns

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2874410A (en) * 1954-06-30 1959-02-24 Du Pont Apparatus for uniformly drawing a plurality of filaments
US2988783A (en) * 1959-10-14 1961-06-20 Union Carbide Corp Method of producing elongated structures of isotactic polystyrene
US2993260A (en) * 1958-02-20 1961-07-25 American Enka Corp Differentially heated draw pin
US3001236A (en) * 1957-07-26 1961-09-26 Bayer Ag Hot stretching of polyacrylonitrile yarns with draw point located on feed roller

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2874410A (en) * 1954-06-30 1959-02-24 Du Pont Apparatus for uniformly drawing a plurality of filaments
US3001236A (en) * 1957-07-26 1961-09-26 Bayer Ag Hot stretching of polyacrylonitrile yarns with draw point located on feed roller
US2993260A (en) * 1958-02-20 1961-07-25 American Enka Corp Differentially heated draw pin
US2988783A (en) * 1959-10-14 1961-06-20 Union Carbide Corp Method of producing elongated structures of isotactic polystyrene

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3416206A (en) * 1964-03-12 1968-12-17 British Nylon Spinners Ltd Means for localizing tension in running yarn
US4075274A (en) * 1973-04-07 1978-02-21 Teijin Limited Method for drawing and heat-treating polyester yarns

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CH383542A (de) 1964-10-31
BE592523A (fr) 1960-10-31
NL253396A (US07816562-20101019-C00012.png)
FR1261142A (fr) 1961-05-12
GB892355A (en) 1962-03-28

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