EP0409743B1 - Yarn-tensioning device for textile machines - Google Patents

Description

The present invention relates to a new type of thread tensioner usable on any type of textile material, and more particularly on machines making it possible to twist and / or twist threads of any kind.

During the various transformation operations that a thread undergoes during its elaboration, it is essential to communicate to it a tension as regular and constant as possible. To do this, numerous solutions of tensioning devices have been proposed to date, among which we may mention that cited in the preamble of French patent no. 2,145,056 and which consists in passing the moving wire in contact with the surface of a pulley or roller subjected to the action of braking means constituted by an eddy current brake as this results from French patent 2,167 957 by braking said wire guide pulley by means of an assembly comprising a magnet whose number of magnetic poles is even, this magnet being placed opposite a disc the face of which is pierced with several holes, disc which supports the wire guide pulley. Braking of the pulley is obtained by varying the distance between the disc and the magnet.

These solutions which can be summarized by the expression "drum braked by magnetic brake" however implies having a "drum" of relatively large diameter (of the order of 80 to 100 mm) if one wants to obtain a good surface. wire adhesion. Furthermore, during start-up, it has the disadvantage of causing voltage surges. Finally and above all, these solutions require pre-braking in the absence of which there can be no adhesion of the wire to the pulley.

To solve these problems, it has been proposed, as is apparent from FR-A-2 295 900, to make tensioning devices comprising two rollers mounted in rotation in a casing and which touch along their circumferences with an adjustable pressure, at least one of these rollers being provided with a bandage of a material having an elasticity of the rubber and the wire to be stretched being guided so that it drives the two rollers when it passes through the device. However, such a device which is widely used today has the disadvantage that, especially given the current high production speeds, the rubber layer heats up during operation, a variation which affects the quality of the wire produced. .

It has also been proposed, in particular in order to obtain a progressive tensioning during the launching of the machine as well as a tension as constant as possible in normal operation of the tensioning devices comprising several rollers mounted free in rotation on a support unit, subject to the action of braking means (magnetic brake), wire guides being provided on the housing upstream and downstream of said rollers if we consider the direction of movement of the wire so that the latter sets in around the periphery of said rollers as it passes through the tensioning device. A solution of this type emerges in particular from document DE-A-3 624 370, corresponding to the preamble of claim 1.

However, such devices still have a certain number of drawbacks, among which we can cite the fact that the output tie-down which is used as a braking multiplier also leads to a multiplication of the occasional running jolts of the coil upstream. Furthermore, the friction conditions on the eyelets can vary as a result of the modification of the surface condition due in particular to the deposition of size, which therefore causes a variation in the output voltage of the wire.

Finally, the braking means of the rollers are generally incorporated therein and they do not make it possible to adjust the tension during operation.

Now we have found, and this is what is the subject of the present invention, a new type of tensioning device which overcomes the drawbacks of previous solutions, in particular by the fact that it eliminates any risk of transmission of jolts. scrolling which can occur upstream of said tensioning device, the output voltage also being maintained at a constant value which is not likely to vary during operation.

Furthermore, according to a preferred embodiment, the braking means are designed so as to allow adjustment during operation.

In general, the tensioning device according to the invention is of the type comprising rollers mounted free in rotation on a support unit, at least one of these rollers being subjected to the action of a braking system with adjustable permanent magnet and the wire during its movement coming to tie around the periphery of said rollers, the displacement of the wire upstream and downstream of the tensioner assembly being produced in a common direction known as the "running axis", said rollers being three in number and being mounted on the support box so that two of these rollers are called "rollers" input "are arranged at the level of the wire introduction zone, on either side of the travel axis, at least one of these input rollers comprising said braking system with adjustable permanent magnet and their mounting being carried out in such a way that they are kept in tangential contact with each other, characterized in that the third roller known as the "output roller" is in turn positioned downstream of the input rollers mentioned above if we follow the path of the wire, its surface tangent to the axis of travel.

In the device according to the invention, the input rollers are preferably rubberized rollers, the output roller having, for its part, a hard surface (for example metallic) to resist friction due to torsion.

Furthermore, the device according to the invention is preferably associated, at the level of the wire entry zone, with a pretensioning device which is also the subject of the present invention and which makes it possible to absorb the reels and prevents them from being passed on downstream.

Various embodiments of the device according to the invention can be envisaged.

Thus, according to a first embodiment, the three rollers are maintained in mutual contact, the second and third rollers being mounted on the housing by means of a lever (or the like) subjected to the action of a return means ( spring..).

According to another embodiment, only the first two rollers are kept in mutual contact, the second roller being, as before, mounted on the housing by means of an articulated arm subjected to the action of a return spring and the third roller being, in turn, mounted along a fixed axis on the housing.

According to another variant in which the three rollers are also kept in mutual contact, the first and third rollers are mounted free in rotation about a fixed axis, the second roller being, for its part, kept under pressure against the two aforementioned rollers by magnetism using a magnet (or any other equivalent system), the second roller can be either completely free and detached from the support box, or mounted on this box by any guide system leaving it free to make its contact with the other two rollers.

Thanks to such a design of a tensioning device, it is possible to eliminate all the occasional jolts which may occur upstream and, moreover, the tension in normal operation is maintained at a constant value, perfectly determined. .

• la figure 1 est une vue schématique en coupe et en élévation d'un dispositif tendeur conforme à l'invention ;
• la figure 2 est une vue de dessus, montrant une forme de réalisation d'un dispositif de prétension annexe associé à un tendeur conforme à l'invention et permettant d'éliminer tous les à-coups de tension lors du dévidage ;
• les figures 3 et 4 sont des vues en coupe selon les axes AA et BB de la figure 1 montrant la structure des galets entrant dans la réalisation d'un dispositif conforme à l'invention ;
• la figure 5 illustre d'une manière similaire à la figure 1 une autre forme de réalisation d'un tendeur conforme à l'invention ;
• la figure 6 illustre d'une manière similaire à la figure 1 une variante selon laquelle les trois galets sont maintenus en contact mutuel, la figure 7 étant une vue de détail en coupe selon B de la figure 6 illustrant la manière dont est réalisée cette mise en contact entre les galets.

The invention and the advantages which it brings will however be better understood thanks to the exemplary embodiments given below by way of indication but not limitation and which are illustrated by the appended diagrams in which:

• Figure 1 is a schematic sectional view in elevation of a tensioning device according to the invention;
• Figure 2 is a top view, showing an embodiment of an additional pretensioner device associated with a tensioner according to the invention and allowing to eliminate all voltage jerks during the unwinding;
• Figures 3 and 4 are sectional views along the axes AA and BB of Figure 1 showing the structure of the rollers used in the production of a device according to the invention;
• Figure 5 illustrates in a similar manner to Figure 1 another embodiment of a tensioner according to the invention;
• FIG. 6 illustrates, in a manner similar to FIG. 1, a variant in which the three rollers are kept in mutual contact, FIG. 7 being a detail view in section along B of FIG. 6 illustrating the manner in which this placing is carried out in contact between the rollers.

In the following description, the wire tensioning device according to the invention will be described by considering that the path of the wire upstream and downstream of said tensioning device is vertical but, of course, this is not limiting.

Furthermore, in the two illustrated embodiments, the same elements are designated by the same references.

In the first embodiment illustrated by Figures 1 to 4, the tensioning device according to the invention consists of a plurality of rollers which are mounted free in rotation on a support housing designated by the general reference (1), itself fixed on the frame (2) of the machine.

In such a device, the wire (3) which is intended to be twisted comes from a power source (not shown) and penetrates inside the support box (1) through a guide eyelet (4) then comes to tie up around the rollers and exits at (25) to be brought to the winding system not shown. The scrolling of the thread upstream and downstream of the tensioning device is carried out along a designated axis XX, in the following description by the expression "scrolling axis".

According to the invention, there are three rollers respectively (5.6 and 7). Each roller is mounted in a known manner on the support box (1) so that during the passage of the wire, the latter drives them in rotation. Braking means are associated with at least one of these rollers, in the present case with the roller (5), an embodiment allowing adjustment in operation and which is also part of the invention, being preferably associated with the first roller (5). The structure of such a braking element will be seen in more detail in the following description.

• les deux premiers galets (5,6) soient disposés à proximité de l'oeillet de guidage d'entrée (4) et sensiblement de part et d'autre de l'axe de défilement (XX) du fil ;
• le troisième galet (7) est, quant à lui, monté au-dessus du second galet (6) et est disposé de telle sorte que sa surface vienne tangenter avec l'axe de défilement (XX) ; de cette manière, en sortie de l'appareil tendeur, le fil ne subit aucun embarrage et sort directement.

In order to prevent the voltage surges produced upstream of the device (1) during the guiding of the wire from being passed on, the rollers (5, 6, 7) are mounted on the support box (1) so that :

• the first two rollers (5,6) are arranged near the inlet guide eyelet (4) and substantially on either side of the thread axis (XX);
• the third roller (7) is, in turn, mounted above the second roller (6) and is arranged so that its surface comes to tangent with the scroll axis (XX); in this way, at the output of the tensioning device, the wire does not undergo any embarrassment and leaves directly.

According to the first embodiment illustrated in Figure 1, the three rollers are in mutual contact, the second roller (6) and the third roller (7) being mounted on pivoting arms (8,9), subjected to the action return springs (10,11) simply shown in Figure 1. The two rollers (5,6) are coated with a layer of rubber while the roller (7) has a hard surface and is preferably made of metal.

In the preferred embodiment of FIG. 1, the roller (7) acts as a torsion ascent blocker and, moreover, as it is kept in contact with the second roller (6), it ensures the holding the wire (3) even when stopped.

In the variant illustrated in FIG. 5, the third roller (7) is not kept in contact with the roller (6), but is mounted to rotate freely on a fixed axis. This embodiment simplifies the design of the tensioner, but on the other hand, the wire is not not perfectly maintained at a standstill as in the preferred embodiment.

In the variant illustrated in FIGS. 6 and 7, the third roller (7) is mounted to rotate freely on a fixed axis, but is also in contact with the second roller (6); the wire is therefore perfectly kept stationary. The second roller (6), as in the preferred embodiment illustrated in Figure 1, is in contact with the inlet roller (5) and the third outlet roller (7). This second roller 6) is kept under pressure against the other two by magnetism, using a magnet (26), or by any other system making it possible to ensure its contact with the other two rollers. In such an embodiment, the second roller (6) can be entirely free and disconnected from the support box (1) or from any other part relating thereto; it can also be secured to the support block (1) by any guide system giving it complete freedom to make contact with the rollers (5) and (7). Such an embodiment simplifies the design of the tensioning device.

Figures 3 and 4 are sections along the axes AA and BB of Figure 1 showing in more detail the structure of the rollers (5,6,7) that comprises the wire tensioner according to the invention. It should be noted that in the variant illustrated in FIG. 5, the only difference lies in the fact that the third roller (7) is not kept in contact with the roller (6).

If we refer to these diagrams, each roller is mounted on the support box (1) by means of bearings carried by support pins (5a, 6a, 7a). The input roller (5) is, as shown in Figure 3, associated with a braking device designated by the general reference (F) which can be adjusted in operation. This braking device is of the permanent magnet hysteresis type. Any other equivalent device could of course be used. In the illustrated embodiment, this braking device (F) is mounted on the other side of the housing (1) relative to the roller (5). It essentially consists of a fixed body (12) in the form of a cage centered on the axis (5a) of the roller (5), a bearing being interposed between this body (12) and the axis (5a). A disc (13) comprising a hysteresis washer (14) is fixed by means of a screw (15) on the end of the axis (5a). Opposite this disc, is disposed a set of magnets (16) mounted on a ring (17), a ring which can be moved inside the fixed body (12) so as to modify the air gap between the magnets ( 16) and the hysteresis washer (14).

If in most cases a single braking device associated with the first roller (5) is sufficient, it can also be envisaged to associate with the second roller (6) or even also with the third roller (7), a braking element additional not adjustable in operation.

Furthermore, the device according to the invention is preferably associated with an assembly making it possible to eliminate the voltage surges which occur upstream of the inlet eyelet (4). Such a compensator assembly essentially consists of two additional eyelets (20,21) arranged at the entry of the tensioner along the axis of travel XX. One of the eyelets (21) is mounted on a pivoting arm (see Figure 2) while the second is fixedly mounted on the base of the housing (1). Two magnets respectively (23,24) are mounted one on the base of the housing (1) (magnet (23)), the other (24) on the pivoting arm (22). These two magnets are arranged so their faces of the same polarity are facing each other. In this way, the arm (22) tends to be pushed back as illustrated in FIG. 2 in dashed lines and, when the wire (3) passes, a tie is thus formed upstream of the entry eyelet (4). variable to eliminate voltage surges.

Such a tensioning device of simple and particularly effective design, makes it possible to ensure a regular and constant tension in the thread, without variation during operation. In addition, thanks to the braking system accessible from the outside that includes one of the rollers, it is possible to make adjustments during operation. Such a device can be used on any type of textile material.

Claims (8)

1. Yarn tension device of the type comprising rollers (5,6,7) mounted freely rotatably on a support housing (1), at least one of these rollers being subjected to the action of an adjustable permanent-magnet braking system (12-17) and the yarn (3), during its movement, being deflected round the periphery of the said rollers, the movement of the yarn upstream and downstream of the tension assembly being executed in a common direction called the "running axis (XX)", the said rollers being three in number and being mounted on the support housing in such a way that two of these roller called "entry rollers" (5,6), are arranged at the level of the yarn introduction zone, on either side of the running axis (XX), at least one of these rollers (1) having the said adjustable permanent-magnet braking device (12,17), and their mounting being carried out in such a way that said rollers (5,6) are maintained in tangential contact with one another, characterized in that the third roller (7) called in "exit roller", itself being positioned downstream of the abovementioned entry rollers (5,6), in the direction of travel of the yarn, its surface being tangent to the running axis (XX).

2. Tension device according to the claim 1, characterized in that the entry rollers (5,6) are rubberized rollers, the exit roller (7) itself having a hard surface in order to withstand the friction attributable to the torsion.

3. Yarn tension device according one of the claims 1 and 3, characterized in that it is associated, in the region of the yarn entry zone, with a pretension device (20,21) which absorbs the unwinding jolts and which prevents them from having an effect downstream.

4. Yarn tension device according one of the claims 1 to 3, characterized in that the three rollers (5,6,7) are maintained in mutual contact, the second roller (6) and the third roller (7) being mounted on the housing (1) by means of a lever (8,9) subjected to the action of a return means (10,11).

5. Yarn tension device according one of the claims 1 to 3, characterized in that the first two entry rollers (5,6) are maintained in mutual contact, the second roller (6) being mounted on the housing by means of an articulated arm subjected to the action of a return spring, and the third roller (7) itself being mounted in a fixed axis on the housing.

6. Yarn tension device according one of the claims 1 to 3, characterized in that the three rollers (5,6,7) are maintained in mutual contact, the first and third rollers being mounted for free rotation about a fixed shaft, the second roller being itself maintained under pressure against the two aforementioned rollers by magnetism by means of a magnet, it being possible for the second roller to be either entirely free and disunited from the supporting housing or mounted on this housing by any guidance system allowing it full freedom to implement its contact with the other two rollers.

7. Yarn tension device according one of the claims 1 to 6, characterized in that the braking means are associated with the entry rollers (5) and consist of a cage-shaped stationary body (12) centered on the axle (5a) of the roller (5), a bearing being interposed between this body (12) and the axle (5a), a disk (13) which carries a hysteresis washer (14) being fastened to the end of the axle (5a) by means of a screw (15), and a set of magnets (16) being mounted opposite this hysterisis washer (14) on a ring (17) which can be moved inside the stationary body (12) in order to modify the flux gap between the magnets (16) and the hysteresis washer (14).

8. Yarn tension device according one of the claims 3 to 7, characterized in that the pretension device located in the region of the yarn entry zone consists of two additional eyes (20,21) arranged at the entrance of the tension device in the running axis (XX), one of the eyes (21) being mounted on a pivoting arm (22) whilst the second (20) is mounted in a stationary manner on the base of the housing (1), two magnets (23,24) being mounted one (23) on the base of the housing (1) and the other (24) on the pivoting arm (22) in such a way their faces of the same polarity confront one another.

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