EP0802993B1 - Process for stretching-texturing by false torsion and oven for implementing such process - Google Patents

Description

The present invention relates to an improvement made to false twist texturing techniques, and more particularly a new type of process able to be implemented on machines making it possible to treat wires partially or not drawn, at high speed, generally greater than 1000 m / min, the drawing of yarn being produced during the texturing operation.

To date, two techniques known, one under the expression "stretching-texturing sequential ", the other, according to the expression" stretching-texturing simultaneous ", are implemented on texturing machines by false twist, depending on the nature of the treated threads.

In the "sequential stretching-texturing" technique, the machine is designed so that stretching and texturing operations are carried out successively in two separate zones. So we make a simple juxtaposition of well known operations, which allows master perfectly, depending on the nature of the treated threads, operating conditions both in the stretching zone and in the texturing proper. However, this technique presents disadvantage of driving complex and delicate machines to set up in action.

As a result, the technique most used these days is the technique called "simultaneous stretching-texturing" for which the stretching phase is performed on the twisted thread upstream of the false twist spindle, and this by simply adjusting the speeds between the two wire calling systems provided upstream of the oven and downstream of the false twist spindle. This technique, however, poses implementation problems, in particular in the case of polyester yarns which are known to be under control perfectly the area where the necking point is located.

Now we have found, and this is what is the subject of the present invention, a improved false-twist stretch-texturing process that allows not only to keep the advantages of machines putting in works the simultaneous stretch-texturing process, but also those of the sequential stretching-texturing technique, perfecting thanks to to which it is possible to locate very precisely the point of necking of the wire during the stretching phase, imperative condition especially in the case of treatment of polyester yarns.

• une cantre pour l'alimentation en fil non ou partiellement étiré à traiter ;
• un système d'appel permettant de délivrer le fil à une vitesse prédéterminée à l'intérieur de la zone de texturation proprement dite, zone constituée par un four, une piste de refroidissement et une broche de fausse torsion;
• un second appel dont la vitesse est supérieure au premier, d'une valeur correspondant au taux d'étirage à réaliser sur le fil;
• des moyens de renvidage du fil étiré et texturé, éventuellement précédés d'un four de refixation thermique avec un troisième appel disposé immédiatement avant la réception.

In general, the invention therefore relates to a stretch-texturing process by false twist capable of being implemented on a machine consisting, in known manner, of a plurality of identical working positions mounted on a support frame , each position comprising, if we consider the direction of movement of the wire during its processing:

• a creel for the supply of non or partially drawn wire to be treated;
• a call system for delivering the yarn at a predetermined speed inside the texturing zone proper, zone constituted by an oven, a cooling track and a false twist spindle;
• a second call, the speed of which is greater than the first, by a value corresponding to the rate of drawing to be carried out on the wire;
• means for winding the drawn and textured wire, possibly preceded by a thermal re-fixing oven with a third call placed immediately before reception.

The process according to the invention is characterized in that it localizes the necking point on the wire during the stretching phase causing a sudden break or change in the path of the wire during its ascent in temperature in the texturing zone, and this by pressing a surface or element allowing a rise in the reported torsion through the pin to the first call system.

Thanks to such a way of proceeding which goes against what is generally accepted in the texturing field where one of the conditions sought to obtain good regularity of the textured yarn was that the path of said wire is straight in the area from the first deliverer at the output of the false twist pin it was found that better quality of the yarns produced was obtained, particularly in the polyester yarn case.

Such a break in the path of the wire makes it possible to locate the necking point can be achieved possibly by providing additional means for preheating and deflecting the path of the wire before entering the oven proper. Preferably the break trajectory is achieved inside the furnace by adapting said oven so that the change of trajectory takes place during its rise in wire temperature, preferably in the vicinity of the area where it inside the oven reaches its optimum processing temperature.

Such a method is particularly suitable for being applied to so-called "high temperature" ovens which are increasingly offered on false twist texturing machines to reduce the length of the heat treatment area, such as those subject to US-A-5 193,293 (corresponding to EP-A-524,111).

Generally, the type of oven covered by the patent aforementioned comprising a heating block proper, which comprises a succession of cylindrical zones having different diameters, arranged in line with each other, the wire to be treated being kept at a constant distance from the outside surface of small diameter areas so that the temperature rise of the wire is obtained in these radiation areas as it comes into contact with the surface of the areas of large diameter, the heat transmission then being carried out by contact, wire guiding elements being provided along the length of the oven to ensure its positioning.

This type of oven implementing the method according to the invention is characterized in that it comprises, if one follows the trajectory of the wire, a entry area where heating is by radiation followed by a zone contact heating, at the outlet of which are arranged means allowing to modify the trajectory of the wire without however blocking the torsional rise, said trajectory then becoming regular again, straight or curvilinear, the wire then being subjected to a succession of thermal treatments by contact and by radiation until leaving the oven, the last zone being advantageously constituted by a zone of radiant heating.

It has been found that for an oven allowing high treatment temperature (of the order of 600 ° C to 800 ° C), having a length of the order of one meter, an entry area and an exit area allowing a radiation heating, each 100 mm long, provide very good textile characteristics on the yarns treat, especially in the case of polyester yarns. In such a type of oven, the intermediate zone between the entry zone and the exit zone is designed to allow, as said before, a combination radiant heating and contact heating, the length of different zones being adapted according to the wires to be treated.

Advantageously, in such a type of oven design, the zones of different diameters allowing to have such a combination of radiant heating and contact heating, are performed in a similar to the teachings of European patent EP-A-578 589 (patent corresponding to US-A-5 332 882), whose design is such that the active element called "heating block" can be easily removed and reassembled, either to carry out maintenance operations such as the cleaning, or possibly to replace a heating block structure determined by a different block when you want to modify the heat treatment, for example when a wire must be treated different nature.

In such an oven using the process according to the invention, and which is therefore designed so that one of the faces extremities of the enclosure surrounding the insulating enclosure and the heating block is removable and supports all of the fittings ensuring the electric supply of the oven, its regulation ..., that the heating block being fixed by one of its ends of said removable face, in accordance with the improvement according to the invention, the areas of different diameters allowing the combination of heating by radiation and contact heating, consist of a plurality of elementary modules juxtaposed by fitting on the body of cylindrical heater which is fixed by one of its ends to the face removable from the hood of the oven, keeping said modules in position juxtaposed being provided by a positioning and blocking element itself secured to said removable face.

In such an embodiment, the oven is advantageously designed to process two wires in parallel, guiding and positioning the wires inside the oven between the entry through eyelets provided on the face and the outlet through eyelets provided at the other end of the oven, being provided by guides distributed over the length of the heating assembly, thus allowing the path of the wires to be modified which can be either straight or preferably form one or two helices along the length of the oven between the inlet area and the outlet area where the path is straight.

In such an oven, the location of the necking point is obtained in the entry area either during the temperature rise of the wire, or when it reaches approximately the normal temperature of treatment via a large diameter module on which the wire or wires are in contact and at the outlet of which they tie up, which can cause a sudden rupture or modification of the trajectory of said wire, area in which the necking point is located.

Thanks to such an oven design, it is therefore possible not only to locate precisely the area where the stretching takes place wire, but you can also adapt the heating elements to each type of treatment by simple substitution or combination of modules elementary allowing a succession of contact heating and radiant heating, the lengths of which can be adjusted function of the wires, the heater itself being the same for any type of wire.

• la figure 1 illustre schématiquement en vue de côté une position de travail d'une machine apte à mettre en oeuvre le procédé conforme à l'invention ;
• la figure 2 illustre, en perspective schématique, la structure d'un four, qui fait également partie de l'invention, spécialement adapté pour localiser le point de striction du fil lors de son étirage, et ce conformément à l'invention, cette figure montrant la trajectoire du fil lors de son passage à l'intérieur du four ;
• la figure 3 est une vue en perspective éclatée montrant en détail l'élément chauffant d'un four spécialement conçu pour mettre en oeuvre le procédé conforme à l'invention;
• les figures 4 et 5 sont des vues respectivement en perspective éclatée et en élévation en coupe d'un four comportant un élément chauffant réalisé conformément à la figure 3.

The invention and the advantages which it brings will however be better understood thanks to the following description which is illustrated by the appended diagrams in which:

• Figure 1 schematically illustrates a side view of a working position of a machine capable of implementing the method according to the invention;
• FIG. 2 illustrates, in schematic perspective, the structure of an oven, which is also part of the invention, specially adapted for locating the point of necking of the wire during its drawing, and this in accordance with the invention, this figure showing the path of the wire as it passes inside the oven;
• Figure 3 is an exploded perspective view showing in detail the heating element of an oven specially designed to implement the method according to the invention;
• FIGS. 4 and 5 are views respectively in exploded perspective and in sectional elevation of an oven comprising a heating element produced in accordance with FIG. 3.

• une cantre (1) pour l'alimentation en fil (2), non ou partiellement étiré, à traiter;
• un système d'appel (3) permettant de délivrer le fil (2) à une vitesse prédéterminée à l'intérieur de la zone de texturation proprement dite, zone constituée par un four (4), une piste de refroidissement (5) et une broche de fausse torsion (6);
• un second appel (7) dont la vitesse est supérieure au premier (3) d'une valeur correspondant au taux d'étirage à réaliser sur le fil (2) et;
• des moyens de renvidage (R) du fil étiré et texturé, éventuellement précédé d'un four de refixation thermique avec un troisième appel disposé immédiatement avant la réception.

Referring to the appended FIG. 1, each working position of the machine implementing the method according to the invention comprises, like any false twist texturing machine:

• a creel (1) for the supply of wire (2), not or partially drawn, to be treated;
• a call system (3) making it possible to deliver the yarn (2) at a predetermined speed inside the texturing zone proper, zone constituted by an oven (4), a cooling track (5) and a false twist pin (6);
• a second call (7) the speed of which is greater than the first (3) by a value corresponding to the rate of stretching to be carried out on the wire (2) and;
• means for winding up (R) the drawn and textured wire, possibly preceded by a thermal re-fixing oven with a third call placed immediately before reception.

According to the invention, this machine includes means which allow to modify the trajectory of the wire (2) during its rise in temperature in the texturing area, preferably inside even from the oven (4) in the vicinity of the zone where it reaches its temperature optimal treatment, while allowing torsional rise communicated by pin (6) until the first call (3).

Such a rupture of the trajectory which makes it possible to locate the point of necking during the stretching phase, can possibly be carried out providing means for preheating and deflecting the path of the wire (2) before entering the oven (4).

Such means will however preferably be integrated into the oven (4) himself.

Such a possibility of integration of means allowing locate the necking point inside the oven itself, may be obtained in a simple way by an adaptation of the ovens of the type making the subject of patents US-A-5,193,293 and US-A-5,332,882, mentioned in the preamble, it being expected that it does not depart from the scope of the invention in modifying the structure of other types of known ovens to obtain such a change of the trajectory of the wire.

In general, for the implementation of the invention, the oven will advantageously be of the type comprising a heating block (B) proper which comprises a succession of cylindrical zones (see Figure 2) having different diameters D and d arranged in the extension of each other. During its passage inside the oven, the wire (2) to be treated is kept at a constant distance from the sections of small diameter d, the rise in temperature being obtained in these radiation zones while in contact with the surface of D zones large diameter.

Guiding means are provided along the length of the oven for ensure the positioning of the wire.

According to the invention, the heating block (B) is designed, if one follows the path of the wire (2), so that it includes an area (10) radiant heating input followed by a first zone (11) of contact heating. Immediately downstream of zone (11) of contact heating, a guide (12) is arranged which makes it possible to locate the necking point on the wire by modifying the trajectory, without however block the rise in torsion communicated by the spindle (6), said trajectory then becoming regular, straight or curvilinear as shown in Figure 2 to the exit of the oven with alternating contact and radiation heating zones. Preferably, the last zone (13) of contact heating is followed by a zone (14) of radiant heating.

Figures 3, 4 and 5 illustrate in detail a furnace implementing the process according to the invention having the general structure of the type of that which is the subject of US-A-5,332,882 (EP-A 578,589).

It essentially consists (see Figures 4 and 5) of an enclosure insulator designated by the general reference (20) and which consists of a refractory block (21) surrounded by an outer cover (22) which surrounds a heating block (BQ) produced in accordance with the invention, with which it defines a longitudinal channel inside passes the wire to be treated.

In the present case, the oven makes it possible to process two wires (2) in parallel.

The insulating block (21), made of refractory material, is advantageously of cylindrical in shape and has a recess, cylindrical in shape, intended to contain the heating element (B) which has a structure such as illustrated exploded in Figure 3.

In this embodiment, the heating element (B) is fixed by one of its ends to one of the end faces (16) of the cowling, this face being removable and supporting fittings (17) ensuring the electric supply of the oven and its regulation.

The heating block (B) is designed so as to present a succession zones with different diameters D and d, so that the wires (2) are in contact with the large diameter zones D, the heat transmission then being carried out by conduction and are kept away from areas of smaller diameter d, the transmission of heat is then obtained by radiation.

The guidance and positioning of the wires (2) inside the oven between the entry through the eyelets (18) provided on the face (16) and the exit at through eyelets (19) provided at the other end of the oven, is provided by through guides (30,31,32). These guides are spread over the length of the heating assembly and allow the path of the wires so that it is for example rectilinear over part of the length of the oven, in this case in the entry area (10) and in the exit (14), then helically in one or more successive zones, in the case present in the two middle zones.

According to the invention, the wires tangent with the areas of large diameter D where they are heated by contact and are kept spaced from the surface of small diameter areas where heating is achieved by radiation.

For the implementation of the process according to the invention, in a such embodiment, the abrupt change in the trajectory of the wire to the interior of the oven is obtained by associating with the first module (11) of diameter D the first guide element (30) which is designed so to wire the wire on the edge (11a) of the module (11) and which therefore serves as guide (12), thus making it possible to locate the point of necking in this zoned. The length of the wire contact area on this first module (11) may be variable depending on the nature of the wires and will generally be in the range of 2 to 10 cm.

In such a type of oven, the heating element (B) is designed as as shown schematically in Figure 3, and consists essentially a cylindrical heating body (15), shown in dotted lines, comprising one or more resistors embedded in a matrix and obtained by molding. This heater also has an element thermocouple allowing precise regulation of the temperature. Depending on the treatments to be performed, the resistances can be designed in different ways, for example to have a constant temperature over the entire length of the oven or to have variable temperatures, in which case we could, for example, have in parallel two resistors which can either be of the same length or be offset from each other along the length of the oven.

In this embodiment, to produce a succession of zones of different diameters, elementary modules are used whose length can be adapted according to the treatments to be carried out, which can be slid onto the heating body (10), and which constitute cylindrical surfaces of different diameter D and d. Each module can either alone form a small diameter area d, either a large diameter area D, or possibly combine a alternation of large diameter zones D and small diameter zones d as shown in figure 3.

The internal diameter of each module corresponds to the diameter external of the heating resistor (15) so that the modules can be fitted by simple sliding around the latter.

Thanks to such a design, it is possible to adapt the structure of the oven depending on the heat treatment to be performed and the type of wire to treat.

Maintaining the position of the various modules and guides around the heating body (10), is produced by any suitable means, for example by means of a locking ring or by means of screws, the different modules being locked longitudinally via a tie rod (17) integral with the entry face (6), and the end (33) of which comes snap into a notch (34) provided in the outlet guide (32). radiation The positioning of the first module (11) relative to the oven inlet is adjusted by means of a spacer (35) appropriate length to define an entry area (10) where carried out radiation heating which may have a suitable length as needed.

Thanks to such a design, it is therefore possible to easily adapt the heating element under the treatment conditions and the materials to be treated by modifying the length of the zones of large diameter D and of small diameter d1 and by modifying their positioning along the length of the oven.

Such a type of oven makes it possible to carry out a drawing operation texturing of all types of synthetic yarn including polyester yarn, wire neck point being perfectly located during the phase stretching.

The implementation of the process according to the invention will emerge however better from the concrete example of realization given below to indicative, but not limiting.

Example :

On a false twist texturing machine as shown in Figure 1, we treat a polyester yarn, partially drawn, having a title of 167 dtex before treatment and comprising 34 strands.

This machine is equipped with a 100 cm high temperature oven in length, having a structure as shown schematically in Figure 2 and which has an entry area (10) for radiant heating having a length of 20 cm followed by an area (11) with a diameter of diameter D of contact heating of 2 cm. At the exit of this zone (11) contact heating, the path of the wire (2) is deflected by the guide (30), which therefore results in an embarrassment with said surface (11) making it possible to locate the point of necking. Downstream of the deflection guide (30), are arranged in a succession of zones of diameter D and of diameter d, having a length of 1.2 cm and 5.5 cm respectively, the path of the wire being regular, straight or curvilinear until taken out of the oven. The last zone (13) of diameter D is followed by a zone (14) of diameter d having a length of 16 cm where radiant heating takes place.

The heating element embedded inside the block, element not shown in Figure 2 attached, is brought to a temperature of 600 ° C.

The oven is followed by a cooling zone (5) of length 1.25 meters and a false friction spindle with external friction (6) rotating at a speed of 11,000 rpm, comprising discs in ceramic.

The speed of the output deliverer (7) is set to 1000 m / min, allowing a stretch of 1.73.

Downstream of the deliverer (7), a conventional fixing oven is arranged, not shown in Figure 1, having a length of 1.20 m and brought to a temperature of 200 ° C.

The winding speed is 980 m / min.

By proceeding in this way, a wire is obtained which has the following characteristics: resistance 650 g elongation 22% elasticity 27% curly 18% stability 85%

The machine according to the invention allows, in production industrial, to eliminate the presence of broken strands and allows to obtain a very homogeneous production between the different positions of processing from one machine to another.

Claims (7)

1. Drawing/false-twist-texturizing process capable of being implemented on a machine consisting, in a known way, of a plurality of identical work positions mounted on a support frame, each position comprising, in the direction of movement of the yarn during its treatment :

   a creel (1) for supplying unoriented or partially oriented yarn (2) to be treated ;

   a feed system (3) enabling the yarn (2) to be delivered at a predetermined speed into the texturizing zone proper, which zone consists of an oven (4), a cooling track (5) and a false-twisting spindle (6);

   a second feed (7), the speed of which is greater than the first (3), having a value corresponding to the degree of drawing to be carried out on the yarn (2) ;

   means for winding up the drawn and textured yarn, these optionally being preceded by a heat-resetting oven with a third feed arranged immediately in front of the reception,

      characterized in that the point of striction on the yarn during the drawing phase is localized by bringing about a sudden break or modification in the trajectory of the yarn (2) while it is rising in temperature in the texturizing zone, this being achieved by pressing on a surface or element (11) allowing the twist imparted by the spindle (6) to be taken back as far as the first feed system (3).
2. Process according to claim 1, characterized in that the break or modification in the trajectory of the yarn (2) enabling the point of striction to be localized is achieved by means of additional yarns (2) preheating and path-deviating means before the yarn enters the oven (4) proper.
3. Process according to claim 1, characterized in that the break or modification in the trajectory of the yarn (2) is carried out within the actual oven (4), either while the yarn (2) is rising in temperature or in the vicinity of the zone where it reaches, within the oven, its optimum treatment temperature.
4. Oven for implementing the process according to one of claims 1 and 3, comprising a heater unit (B) proper, which includes a succession of cylindrical zones having different diameters d and D, these being arranged directly in line with one another, the yarn (2) to be treated being held at a constant distance from the external surface of the zones of small diameter d in such a way that the temperature rise of the yarn (2) in these zones occurs by radiation, whereas it comes into contact with the surface of the zones of large diameter D, the heat transfer then taking place by contact, yarn-guiding elements being provided over the length of the oven in order to position the yarn,
      characterized in that it includes, going along the trajectory of the yarn (2), an entry zone (10), where the heating takes place by radiation, followed by a zone (11) for heating by contact, after which zone means (12) are arranged enabling the trajectory of the yarn (2) to be modified without, however, preventing the twist from going back, the said trajectory subsequently becoming uniform again, whether rectilinear or curvilinear, the yarn (2) then being subjected to a succession of heat treatments by contact and by radiation right up to the point where it leaves the oven, the final zone (14) advantageously consisting of a zone for heating by radiation.
5. Oven according to claim 4, characterized in that the zones of different diameter (d, D), enabling a combination of heating by radiation and heating by contact to be achieved, consist of a plurality of elementary modules juxtaposed by fitting together on the cylindrical heater (15), fixed via one of its end to a removable face (16) of the oven shroud, the modules juxtaposed along the heater being held in position by a positioning and locking element (17) which is itself fastened to the removable face (16).
6. Oven according to claim 5, characterized in that it is designed for treating two yarns (2) in parallel, the yarns (2) being guided and positioned inside the oven, between the point of entry through little holes (18) provided on the face (16) and the point of exit through little holes (19) provided at the other end of the oven, by means of guides (30,31,32) distributed over the length of the heating assembly.
7. Oven according to claim 6, characterized in that the trajectory of the yarn inside the oven is modified by means of the yarn inside the oven is modified by means of a module (11) of diameter D associated with a guide (30) enabling the yarn (2) to be deflected against the further edge (11a) of the said first module (11).

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