EP0636720A1 - Apparatus for thermally treating moving yarns - Google Patents

Abstract

Device for the heat treatment of moving threads, for example during a texturing stretching operation. It is designed to subject the wire to two successive treatments, one at a high temperature, the other at a normal treatment temperature. It is characterized in that these successive phases are obtained by means of a heating block (1) constituted by a cylindrical assembly comprising two heating zones (A, B), on either side of which are provided means guide for the wire, zones obtained by means of two resistors (R1, R2) embedded inside the cylindrical assembly, mounted in parallel, offset relative to each other over the length of the block , and each associated with a thermocouple element (TC1, TC2) allowing precise regulation of said temperature. <IMAGE>

Description

The present invention relates to an improvement made to devices for the heat treatment of moving wires, in particular the heat treatment of wires in order to give them certain shrinkage properties and / or bulkiness and / or elasticity.

In all wire transformation processes requiring heat treatment, the main problem that arises is that of rapid heat transmission, the heat having to rise regularly to the core and in the same way over the entire length of the wire. Indeed, as we know, the temperature of the treatment and its regularity have a very great influence on the qualities of the wire.

It is well known that the heat treatment varies according to the material treated, the title of the wire and its speed of passage inside the oven. Thus, it is easy to see that we will reach the heart of a fine wire more quickly than that of an important track. Likewise, we know that you cannot wear a wire above a certain ceiling temperature, otherwise you will degrade it. Consequently, this question of heat exchange being very important in the field of texturing, very many solutions have been envisaged to resolve it, these solutions calling upon the three main principles of heat exchange, namely convection, radiation. , conduction (direct contact with the heating surface).

In addition to this problem of good heat transfer, there is also the problem of keeping the wire under a determined tension, depending on the treatment which is carried out. Thus, for example in the case of a drawing operation, possibly combined with a texturing operation, it is necessary that the thread is kept under a maximum tension whereas, on the other hand, when it is desired to shrink the wire, the tension should be reduced. Finally, there is also the problem of increasing production speeds on a textile machine, which has gone from a few tens of meters per minute about thirty years ago to a thousand meters, or even more, at present and which has had the consequence of leading to very bulky installations ovens becoming longer and longer and up to two meters.

Among the various solutions proposed to obtain very good regularity in the heat transmission and also to facilitate the problems of temperature regulation from position to position on a machine so that the entire production is homogeneous, it has been envisaged for a long time to perform heat treatments that could be described as "sequential", by making ovens along the length of which follow several distinct heat treatment zones. Among these solutions, mention may be made of that which is the subject of French patent n ° 1 204 634 (corresponding to US patent 3,015,872) in which two successive treatments are carried out inside the same oven, one during which the wire is subjected to a temperature considerably higher than that of the normal temperature to which it must be brought, and this for a period such that it is not damaged, this first phase being followed by an equilibrium treatment at a temperature bringing the wire to a conventional temperature.

Such a solution, used industrially since 1953 on the machines marketed by the company HOBOURN AERO COMPONENTS Ltd, under the reference "HOBOURN - EP1", which is attractive by the fact that it makes it possible to considerably reduce the length of the ovens for a speed given scrolling has however been abandoned for a very long time by the manufacturers of textile materials, which can be explained by the fact that it required apparatuses of complex design, difficult to implement.

However, we have found, and this is what is the subject of the present invention, a new type of oven of particularly simple design, which not only makes it possible to carry out such “sequential” heat treatments, but also offers the particularity to be able to be easily adapted for, depending on the treatments to be carried out and the nature of the wires to be treated, having successive zones in which the transmission of heat to the wires can be carried out by combining over its length zones implementing the different principles heat exchange, and more particularly successive zones where heat is transmitted by radiation or conduction.

Such an oven design also virtually eliminates the risk of vibration, which can cause irregularities in the production of son, and allows high production speeds while having a particularly compact heating assembly.

In general, the new type of oven according to the invention for the heat treatment of a wire, for example during a texturing stretching operation, is of the type constituted by an insulating enclosure which surrounds a heating block with which it defines a "channel" which can be opened to the outside, inside which passes the wire to be treated, means for guiding said wire being provided to ensure its positioning inside said oven, and in which subjects the moving wire to two successive treatments, one during which the temperature is higher than that of the normal temperature to which it must be brought, and for a period such that it is not damaged, the first phase being followed by an equilibrium treatment at a temperature bringing the wire to a conventional temperature, and it is characterized in that these successive phases are obtained by means of a heating block constituted by a cylindrical assembly comprising two heating zones, on either side of which are provided means for guiding the wire, zones obtained by means of two resistors embedded inside the cylindrical assembly, mounted in parallel, offset relative to each other over the length of the block, and each associated with a thermocouple element allowing precise regulation of said temperature.

Thanks to such a design, two separate heating zones are thus obtained, one being able to be at a high temperature, the other at a lower temperature, thus making it possible to have a rapid rise in temperature of the wire to a close level. of its optimum processing temperature, followed by a stabilization phase at said optimum wire processing temperature.

If it can be envisaged to carry out a heat treatment only by radiation, the cylindrical block then comprising only, at least three elements for guiding the wire (rings), one at the inlet, one at the outlet and one on its central part. , according to a preferred embodiment, it is designed to allow a combination of the two types of heat treatment by convection and conduction, and this in accordance with the teachings of European patent no. 524 111 in the name of the Applicant and includes a large diameter zone (sleeve) against which the wire is in contact, preferably along a helical path.

According to a variant, the cylindrical heating block is associated with two "sleeves" of the same diameter, preferably spaced from one another, the tangent wire, preferably helically with the surfaces of said sleeves, thus allowing to have an exchange thermal by contact (conduction) and separated from each other by an area where the wire is heated by radiation.

Finally, if the resistors can directly transmit their calories to the blocks inside which they are mounted, it could be envisaged to carry out the heating, to have the resistors in a second enclosure comprising a DOWTERM liquid.

From a practical point of view, according to a preferred embodiment according to the invention, the heating block is constituted by a ceramic or stainless steel cylinder, the two electrical resistances being embedded inside this cylinder and being each associated with a thermocouple element, the electrical supply and the connections of the thermocouple elements being located on the same face.

Furthermore, if such an oven can be used to treat only one wire, it can also be designed so that two wires can be treated simultaneously, the separate holding of the two wires inside the oven being obtained either by means of suitable guiding elements, possibly by making grooves on the very surface of the "sleeve" of the zone or zones where the heat transmission is carried out by contact.

• les figures 1, 2 sont des vues schématiques, respectivement en élévation et en coupe, et vu de côté d'un bloc chauffant réalisé conformément à l'invention et permettant d'obtenir deux zones de température successives sur la longueur du four proprement dit;
• les figures 3 et 4 sont respectivement des vues en perspective et en élévation d'un bloc chauffant conforme à l'invention, utilisé pour réaliser un four tel que décrit dans le brevet européen 0 524 111 du Demandeur;
• les figures 5 et 6 illustrent également en perspective et en élévation une autre forme de réalisation d'un four au moyen d'un bloc conforme à l'invention et dans lequel le traitement thermique s'effectue par deux zones de contact séparées l'une de l'autre par une zone par radiation;
• la figure 7 illustre une variante d'un four comportant deux zones de chauffage par contact séparées l'une de l'autre par une zone de radiation, permettant de traiter simultanément deux fils et de les guider automatiquement sans adjonction d'éléments de guidage additionnels sur la longueur dudit four;
• la figure 8 illustre une variante de la manière dont est réalisé le chauffage.

The invention and the advantages which it brings will however be better understood thanks to the exemplary embodiments given below by way of non-limiting illustration and which are illustrated by the appended diagrams, in which:

• Figures 1, 2 are schematic views, respectively in elevation and in section, and seen from the side of a heating block produced in accordance with the invention and making it possible to obtain two successive temperature zones over the length of the oven proper;
• Figures 3 and 4 are respectively perspective and elevation views of a heating block according to the invention, used to make an oven as described in European patent 0 524 111 of the Applicant;
• Figures 5 and 6 also illustrate in perspective and in elevation another embodiment of an oven by means of a block according to the invention and in which the heat treatment is carried out by two separate contact zones one on the other by a radiation zone;
• FIG. 7 illustrates a variant of an oven comprising two contact heating zones separated from each other by a radiation zone, making it possible to simultaneously treat two wires and to guide them automatically without the addition of additional guide elements along the length of said oven;
• FIG. 8 illustrates a variant of the way in which the heating is carried out.

FIGS. 1 and 2 illustrate the structure of the heating block making it possible to produce the new type of oven in accordance with the invention, and which consists essentially of a cylindrical core, designated by the general reference (A) in a material which does not conduct heat, steel for example. The temperature rise of this block (A) is obtained, in accordance with the invention, by means of two resistors (R1, R2), each associated with the thermocouple element TC1, TC2, mounted in parallel and positioned offset over the length of said block (B). These two resistors (R1, R2) make it possible to create two different temperature zones along the length of the block, thus offering the possibility of carrying out a "sequential" type heat treatment.

The two resistors (R1, R2) therefore make it possible to create over the length of the block (A) two zones (A, B) which may have different temperatures, the zone (A) corresponding to the resistance (R1) and the zone (B ) to resistance (R2). Each resistor has a structure calculated so that the block is brought to high temperature in zone (A) (between 400 and 700 ° C), and to a low temperature, corresponding to the optimal temperature for processing a synthetic yarn (between 150 and 250 ° C) in zone B. Furthermore, these resistors (R1 and R2) can either have a structure such that they dissipate power evenly over their entire length, or as shown in FIG. 1, be designed so that the resistance dissipates a variable power along its length, for example lower in the first part and stronger in the final phase.

As an indication, a resistance (R1) of 600 watts, designed to dissipate over its length R1 a power of 3.3 watts per square centimeter and a resistance R2 of 400 watts, designed to dissipate over its length on the one hand, a power of 1.2 watts per cm² in a first zone and, on the other hand, a power of 2.4 watts per cm² in its terminal zone, suitable for all applications.

Furthermore, according to the illustrated embodiment, the thermocouple elements TC1, TC2 are arranged inside a duct, which extends over the entire length of the heating block (1). This therefore possibly makes it possible to carry out a verification of the temperature inside a thermocouple control element which is introduced through the free end of said conduits. It should also be noted that according to the preferred embodiment according to the invention, the electrical connections and the outputs of the thermocouple elements are located on the same face.

Such a type of heating block makes it possible to easily produce the ovens which can be adapted according to the wires to be treated, as shown by the concrete examples which follow, and in which the insulating enclosure which the ovens produced from such a block comprise heating, has not been shown for simplification purposes.

In the embodiment illustrated in FIGS. 3 and 4, the block is associated with the wire guiding elements constituted by rings (2,3,4) positioned at the inlet, in the middle part and at the outlet of the oven. over the length of the zone B corresponding to the resistance R2, is arranged a cylindrical sleeve D made of ceramic or of surface-treated steel. The guide elements (2,3,4) are designed so that in zone A, the wire F is kept spaced from the heating block (1) and is therefore heated by radiation, while in zone B, said wire (F ) tangents with the surface of the sleeve D, and is therefore then heated by contact, treatment therefore being carried out in a similar manner to the teachings of European patent 524 111, except that in zone A, a rise is obtained. temperature of the wire at a level close to its optimal treatment temperature followed, in zone B, by a stabilization phase at said optimal treatment temperature of the wire.

Figures 5 and 6 illustrate another type of oven produced from a heating block according to the invention, comprising a second sleeve D1 disposed around the heating block, spaced along the length corresponding to the zone A of the resistance R1. An oven is obtained in this way in which the temperature rise takes place by contact in the inlet zone D1 and not by convection as in the previous example, followed by a zone C, of length which can be variable for heating by radiation and a contact stabilization zone (zone B).

It should be noted that in this embodiment, the guide rings (2,3,4) are positioned so that the wire (F) comes to tangent in a helix against the two surfaces D1, D, ensuring perfect contact and avoiding the phenomena of vibration.

If in the above example the guide of the wire in the oven is achieved by means of rings, it could be envisaged to use other means, for example as shown in FIG. 7, to produce helical grooves deep into the very surface of the sleeves which are attached around the actual heating block.

Furthermore, the creation of the two temperature zones along the length of the oven could be carried out in another way, for example, as illustrated in FIG. 8, by placing each resistor R1, R2 inside an enclosure additional containing DOWTERM liquid.

Such a heating element design is more particularly suitable for producing ovens for texturing machines, in particular by false twisting, compact ovens making it possible to treat all types of synthetic yarns, such as polyamide, polyester, etc. In such ovens, the two treatment zones A, B can have either identical lengths or different lengths. As an indication and without limitation, in ovens having a length of one meter, the sections A, B can have respectively 350 mm and 450 mm.

Claims (5)

1 / Device for the heat treatment of a moving wire, for example during a texturing stretching operation, of the type constituted by an insulating enclosure which surrounds a heating block with which it defines a "channel" which can be opened on outside, inside which passes the wire to be treated, means for guiding said wire being provided to ensure its positioning inside said oven, and in which the moving wire is subjected to two successive treatments, the one during which the temperature is higher than that of the normal temperature to which it must be brought, and this for a period such that it is not damaged, the first phase being followed by an equilibrium treatment at a temperature bringing the wire at a conventional temperature, characterized in that these successive phases are obtained by means of a heating block (1) constituted by a cylindrical assembly comprising two heating zones e (A, B), on either side of which are provided means for guiding the wire, zones obtained by means of two resistors (R1, R2) embedded inside the cylindrical assembly, mounted in parallel, offset with respect to each other over the length of the block, and each associated with a thermocouple element (TC1, TC2) allowing precise regulation of said temperature. 2 / Device according to claim 1, characterized in that the heating block comprises a large diameter area (sleeve) against which the wire is in contact preferably in a helical path. 3 / Device according to claim 1, characterized in that the cylindrical heating block is associated with two sleeves of the same diameter, preferably spaced from one another, the wire preferably tangent helically with the surfaces of said sleeve, thus allowing to have a contact heat exchange (conduction) spaced from each other by an area where the wire is heated by radiation. 4 / Device according to one of claims 1 to 3, characterized in that the heating block is constituted by a ceramic or stainless steel cylinder, the two electrical resistors being embedded inside this cylinder and being each associated with 1 thermocouple element, the power supply and the connections of the thermocouple elements being located on the same face. 5 / Device according to one of claims 1 to 4, characterized in that it is designed so as to be able to simultaneously treat two son, the separate holding of the two son inside the oven being obtained either by means of elements suitable guiding, or possibly carried out in grooves on the very surface of the "sleeve" of the zone or zones where the heat transmission is carried out by contact.

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