US3559965A - Apparatus for heating synthetic filaments - Google Patents

Abstract

An apparatus for heating a great number of synthetic filaments or a tow uniformly and with good thermal efficiency in a slittype heater while having them run in and out of the slit by disposing a plurality of buffer plates in the slit to obstruct outside air flowing into the slit with the running filaments, and thereby prevent a drop of air temperature in the slit, and make possible a substantially constant air temperature transversely of the slit.

Description

United States Patent lnventors Kinyu lshida;

Yasuhiro Okamura, Ehime-ken, Japan Appl. No. 843,004 Filed July 18, 1969 Patented Feb. 2, 1971 Assignee Teijin Limited Osaka, Japan Priority July 23, 1968 Japan 43/51966 APPARATUS FOR HEATINGSYNTHETIC FILAMENTS 5 Claims, 5 Drawing Figs.

11.5. CI 263/3, 28/62, 57/34, 219/388, 219/524 Int. Cl F27b 9/28 Field of Search 219/388, 536, 537, 524; 34/152; 263/3; 57/341-1; 264/290; 28/62H [56] References Cited UNITED STATES PATENTS 1,656,709 1/1928 Kelly 219/388 2,624,934 1/1953 Munson et a1. 28/62X 2,877,332 3/1959 Senior, Jr. 219/536 3,319,047 5/1967 Jones, Jr. et al. 219/388 3,349,222 10/1967 Johnston 219/388 3,387,833 6/1968 Whittaker et al. 263/3 3,444,357 5/1969 Drugmand 219/535 Primary Examiner-Volodymyr Y. Mayewsky Attorney-Wenderoth, Lind and Ponack ABSTRACT: An apparatus for heating a great number of synthetic filaments or a tow uniformly and with good thermal efficiency in a slit-type heater while having them run in and out of the slit by disposing a plurality of buffer plates in the slit to obstruct outside air flowing into the slit with the running filaments, and thereby prevent a drop of air temperature in the slit, and make possible a substantially constant air temperature transversely of the slit.

PATENTEU FEB 21% EDGE CENTER E1565 POSITION (P) INVENTORS KINYU ISHIDA and YASUHIRO OKAMURA y APPARATUS FOR HEATING SYNTHETIC FILAMENTS The instant invention relates to an apparatus for heating synthetic filaments or a tow for their heat-drawing and heattreatment.

Further, the invention relates to a slit-type heating apparatus wherein a great number of running synthetic filaments or a tow are less apt to be given inconsistent mechanical properties such as fiber strength, heat shrinkage, etc., because air temperature drop is prevented and consistent heating is provided in the slit-type heating apparatus.

After the extrusion from spinnerets, synthetic filaments are generally heat-drawn to several times their original lengths with a feed roll running at a specified peripheral speed and a draw roll running several times as fast as the feed roll and are then heat treated. As a heating apparatus ,for the heat-drawing and heat-treatment of such synthetic filaments, there have heretofore been used such devices as a steam heater, an infrared ray heater, a fluidized bed heater, a hot-air circulation system, a heating member contact system, etc. Among them, a so-called slit-type heater wherein filaments are advanced in a narrow passage excels the others in the ease of operations, the simplicity of the equipment, and absence of fiber damage due to friction, said slit being formed by having a pair of heating plates facing each other.

However, the disadvantage of this slit-type heater is that cold air accompanying a large number of running filaments is introduced through the entrance into the inside of the slit and thereby the temperature within the slit of the heating apparatus falls, resulting in the lowering of heating efficiency. Then this is followed by an inconsistency of the temperature within the apparatus.

It has been found that there is a difference between the I heating of the filaments running through the center of the slit and those running through the ends, with undesirable results such as variations in strength and elongation, heat shrinkage, etc.

In order that the above disadvantage may be eliminated, the instant invention has been made. A plurality of buffer plates are installed in the slit; the air accompanying the running filaments is thereby blocked and diverted, and consequently the temperature differences in the lateral direction of the slit have successfully been decreased.

It is the object of the instant invention to prevent cold air from flowing from the entrance into the slit of a slit-type heating apparatus accompanying a number of the running filaments and to thereby prevent the lowering of thermal efficiency.

It is a further object of the instant invention to eliminate the inconsistency of air temperatures in the slit-type heater and to heat the whole of the running filaments uniformly.

One embodiment of the instant invention will be described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a slit-type heating apparatus according to the instant invention in the opened state;

FIGS. 2a2c are vertical sections showing various types of buffer plates located inside the slit; and

FIG. 3 is a heat distribution diagram showing heat distribution measured transversely of the slit.

Test results of measuring temperature with a number of thermocouples disposed transversely of slit-type heaters are shown in FIG. 3. In the drawing, the abscissa (P) denotes the positions of the measurement, which extend transversely of the interior of the heater from one side to the other across the center, and the ordinate (C.) denotes the measured temperature. The plotting of the test results for a conventional slit-type heater is shown in curve A. It is seen that there is a drop in temperature in the center of the slit.

Referring to FIG. 1, the slit-type heater of this invention comprises an upper heating plate 1 and alower heating plate 2;shallow grooves 3 and 3' are provided in the central surfaces ofheating plates 1 and 2 facing each other, and a slit is defined bygrooves 3 and 3' whenheating plates 1 and 2 are put together; a number within filaments run along the space of the slit and are subjected to heating. Inheating plates 1 and 2,

heating elements, for instance,electric resistors 6 and 6' may be embedded as shown in the drawing, or hollow spaces may be provided in the interior of theplates 1 and 2 to permit steam or other heating fluids flow through them. It is desired that the space formed bygrooves 3 and 3' be as narrow as possible, for the narrowness helps prevent outside air having lower temperatures from flowing into the slit. However, while a number offilaments 5 are running into the slit, outside air enters the slit, accompanying the filaments. The amount of outside air entering is intense in the center of the slit and somewhat gentle at both ends. In FIG. 3 showing heating distribution, the heating at the center is less than at the ends. This is because a greater amount of outside air having a lower temperature than the temperature within the slit enters the center of the slit and the temperature there drops to a greater extent. In order that the fault may be corrected, a plurality of buffer plates are placed in the slit formed withgrooves 3 and 3' as shown in FIG. I. Said buffer plates may be mounted on upper heating plate I only or on thelower heating plate 2 only. It is desirable to secure the buffer plates so that they are almost at right angles to the runningfilaments 5, but this does not mean that they must be positioned as such a right angle.Buffer plates 4 and filaments S are preferably closely adjacent each other, but contact between them should be avoided because the filaments may be damaged by friction. The greater the number of bufier plates, the better will be the effect.

The buffer plates may be mounted in bothgrooves 3 and 3 alternately, in corresponding positions, or irregularly. FIGS. 20-20 are vertical sectional side views of slit-type heaters provided with various types of buffer plates. FIG. 2 a shows heater having I-shaped plates, FIG. 2b a heater having T- shaped plates, and FIG. 2c a heater having L-shaped plates. FIG. 3 shows heat distribution measured transversely of the slit at positions cm. from the entrance, when a slit-type heater having a slit being 2 m. long, 20 cm. wide, 3 cm. high was heated to 340 C. and I0 polyethylene terephthalate drawn yarns of 2,000 denier each positioned parallel to each other and at equal intervals were advanced at a speed of 250 m./min. Curve A denotes the case whenbuffer plates 4 were not provided, and the center of the slit has very low heating temperatures as compared with the ends of the slit. This is because near the center greater amounts of outside air accompany the running filaments and flow into the slit. On the other hand, curve B shows the heat distribution in the same slit-type heater wherein 20 I-shaped bufler plates as shown in FIG. 2 were mounted on the upper and the lower heating plate respectively at equal intervals and alternately.

It was found that with this apparatus thermal efficiency was enhanced and the unevenness of temperature transversely of the slit disappeared.

When the buffer plates were not employed, there was 2.8 percent difference in shrinkage percentage at the boil between filaments at the ends of the slit and those in the center, but there was only 0.3 percent when buffer plates were employed.

As stated above, according to the instant invention, outside air having a temperature is prevented from flowing into the heater, and thereby thermal efficiency can be enhanced, and further because variations in heating in the lateral direction of the slit are eliminated, filaments can be heated uniformly. Thus conventional slit-type heaters have been remarkably improved.

We claim:

I. A slit-type heater for heating synthetic filaments comprising a pair of opposed heating plates of heat conductive material, each having a groove along the face thereof facing toward the other heating plate, the grooves together defining an elongated slit when the heating plates are against one another, a heating means in each heating plate for heating the heating plate, and a plurality of buffer plates positioned at spaced intervals along the groove in each heating plate and extending from the bottom of the groove in a direction out of the groove substantially perpendicular to said groove and from one side to the other side of said groove and terminating sufficiently short of the surface of the heating plate which is to abut the surface of the other heating plate to provide a space between the buffer plates sufficiently large to allow the filaments to run through the slit without contacting the buffer plates, whereby the temperature transversely of the slit is made substantially uniform by the action of the buffer plates in preventing outside air from being drawn into the slit by the movement of the filaments through the slit.

2. A slit-type heater as claimed in claim 1 in which said buffer plates in one heater plate are offset in the direction of the length of the slit from the buffer plates in the other heater plate.

3. A slit-type heater as claimed in claim I in which said buffer plates are l-shaped in cross section.

4. A slit-type heater as claimed in claim 1 in which said buffer plates are T-shaped in cross section with the crossbar portion thereof adjacent the other heater plate.

5. A slit-type heater as claimed in claim 1 in which said buffer plates are L-shaped in cross section with the transverse portion thereof adjacent the other heater plate.

Claims (4)

1. 2. A slit-type heater as claimed in claim 1 in which said buffer plates in one heater plate are offset in the direction of the length of the slit from the buffer plates in the other heater plate.
2. 3. A slit-type heater as claimed in claim 1 in which said buffer plates are I-shaped in cross section.
3. 4. A slit-type heater as claimed in claim 1 in which said buffer plates are T-shaped in cross section with the crossbar portion thereof adjacent the other heater plate.
4. 5. A slit-type heater as claimed in claim 1 in which said buffer plates are L-shaped in cross section with the transverse portion thereof adjacent the other heater plate.

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