EP0900171B1 - Yarn tensioning device and textile machine equipped therewith - Google Patents

Abstract

PCT No. PCT/FR97/00395 Sec. 371 Date Jun. 18, 1998 Sec. 102(e) Date Jun. 18, 1998 PCT Filed Mar. 6, 1997 PCT Pub. No. WO97/38932 PCT Pub. Date Oct. 23, 1997A yarn tensioning unit for use in a textile machine that includes a shaft having a pulley mounted for rotation thereon over which yarn is conducted. A pneumatic cylinder is slidably mounted on the shaft which contains a piston that is affixed to the shaft to form an expandable chamber with one end wall of the cylinder. The opposite end wall of the housing is magnetically coupled to the pulley to establish a magnetic brake for the pulley. The spacing between the cylinder end wall and the pulley is adjusted by controlling the flow of fluid into and out of the expandable chamber to vary the magnetic braking force exerted upon the pulley.

Description

The present invention relates to a new type of thread tensioner usable on any type of textile material, and more particularly on machines for twisting and / or twisting yarns of any kind.

A device according to the preamble of claim 1 is known from document DE-A-2 016 263.

During the various processing operations that a yarn undergoes during its development, it is essential to communicate a tension as regular and constant as possible. To do this, very numerous solutions for tensioning devices have been proposed to date, the simplest of which is to simply tie the thread on return elements constituted for example by two discs plated one against the other and subjected to the action of a spring.

These solutions do not allow precise control of the tension that is communicated, various proposals have been made to solve these problems.

Thus, as mentioned in the preamble of FR-A-2 145 056, it has been proposed to use tensioning devices which include on the one hand, a pulley whose periphery has a friction layer and is in contact with the wire over at least part of its circumference, and on the other hand, means for braking said pulley. These means of pulley braking consist of an eddy current brake having the form of an asynchronous type motor whose rotor is integral with the pulley shaft and whose stator windings are powered by an adjustable direct current source. Such a type of tensioner which, in general, corresponds to the device making the subject of US-A-3 797 775, is not satisfactory, in particular by the fact that it requires a power supply and therefore it is necessary to have as many power connections as there are tensioning devices.

The aforementioned FR-A-2 145 056 aims to overcome this drawback, the braking device which he describes being constituted by a generator electric whose rotor is secured to the pulley shaft, and whose armature is connected to a load resistor, the magnetic field of the generator being supplied by a permanent magnet.

The solution described in this document also allows you to be able to simultaneously adjust the voltage communicated by a plurality of tensioners. However, it has drawbacks to be expensive and above all requires very high precision in its construction.

FR-A-2 167 957 describes a solution in which braking for wire guidance is obtained by making 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 pulley of wire guide. Braking of the pulley is obtained by varying the distance between the disc and the magnet.

This last solution, if it avoids the problem of electrical connections, however in no way allows to consider simultaneously control all the tensioners that may include a textile machine having a multiplicity of working positions identical arranged side by side.

Now we have found, and this is what is the subject of the present invention, a new type of tensioning device which overcomes the disadvantages of previous solutions and which not only avoids a power supply, but also ensures progressive tension when starting the machine, tension which remains constant in normal operation. In addition, the setting of all or part of the tensioning devices that the machine can include when it is made up of a plurality of work positions identical, can be performed simultaneously on all issuers who perform the same function. Finally, the device according to the invention makes it possible to obtain a very large range in the voltages likely to be communicated to the wire and is usable for yarns which can have very different characteristics from each other.

In the following description, the invention will be described for a tensioner used on a wiring machine, and in which the element communicating the voltage, an element which will be designated in the rest of the description by the expression "pulley", consists of two cups mounted on a hub and locked against each other with a nut to adjust the pressure between the cups and therefore to drive the wire in a positive way. Obviously any other device equivalent could be used, for example, it would be possible to achieve a tensioner according to the invention by passing the wire against the periphery of a drum or a simple grooved pulley.

• une poulie montée libre en rotation à l'extrémité d'un axe porté par un boitier, contre la surface de laquelle le fil est en contact ;
• des moyens de freinage de ladite poulie constitués par des aimants permanents disposés concentriquement et bloqués en rotation par rapport à l'axe, et disposés en regard d'une couronne en matériau ferro-magnétique montée sur le palier supportant la poulie ;
• des moyens permettant de faire varier l'écartement entre les aimants et le palier porte-poulie par coulissement de l'un de ces éléments sur l'axe, ces moyens étant constitués par un premier ensemble exerçant une poussée tendant à rapprocher le support des aimants de la couronne associée à la poulie jusqu'à une valeur minimale prédéterminée.

In general, the wire tensioning device according to the invention is of the type comprising:

• a pulley mounted free in rotation at the end of an axis carried by a housing, against the surface of which the wire is in contact;
• braking means of said pulley constituted by permanent magnets arranged concentrically and locked in rotation relative to the axis, and arranged opposite a ring made of ferro-magnetic material mounted on the bearing supporting the pulley;
• means for varying the spacing between the magnets and the pulley bearing by sliding one of these elements on the axis, these means being constituted by a first assembly exerting a thrust tending to bring the support of the magnets of the crown associated with the pulley up to a predetermined minimum value.

The device according to the invention is characterized in that the means for adjusting the spacing between the magnets and the pulley to be braked, comprise a second assembly exerting a counter-thrust, of adjustable value, tending to separate the magnets relative to the surface of the crown, said counter-thrust means being constituted by a source of compressed air acting on the face of a piston mounted fixed on the axis, bearing against a bearing surface of the latter, and the other of which face is subjected to the action of the first thrust means, the supply of compressed air being carried out simultaneously on all the tensioners that the machine comprises via a common pneumatic line.

The variation of the spacing between the magnets and the crown associated with the pulley to adjust the tension communicated to the wire by the tensioner, can, according to the invention, be obtained either by displacement longitudinal of said magnets on the axis carrying the pulley, said axis being then fixedly mounted on the machine frame, either by displacement of the axis support of said pulley, the attachment to the frame of the machine then being produced through the box supporting the magnets.

• la figure 1 est une vue d'ensemble d'une machine textile permettant de réaliser le câblage de deux fils élémentaires équipés d'un tendeur conforme à l'invention ;
• la figure 2 est une vue de détail en coupe longitudinale d'un tendeur réalisé conformément à l'invention ;
• la figure 3 est une vue de face d'un tel tendeur montrant la manière dont s'effectue le passage du fil autour de la "poulie" permettant de communiquer la tension ;
• la figure 4 illustre, vue de dessus, une pluralité de tendeurs équipant quatre positions d'une machine textile, reliés à une source d'alimentation d'air sous pression commune.

The invention and the advantages which it brings will however be better understood thanks to the example of embodiment given below and which is illustrated by the appended diagrams in which:

• Figure 1 is an overview of a textile machine for making the wiring of two elementary son equipped with a tensioner according to the invention;
• Figure 2 is a detail view in longitudinal section of a tensioner produced in accordance with the invention;
• Figure 3 is a front view of such a tensioner showing the manner in which the passage of the wire around the "pulley" is used to communicate the tension;
• FIG. 4 illustrates, seen from above, a plurality of tensioners equipping four positions of a textile machine, connected to a source of supply of air under common pressure.

Figure 1 illustrates, schematically and viewed from the side, a working position of a so-called "direct cable" textile machine, allowing two elementary wires to be assembled by false twist.

In such a type of machine, known for a very long time (see US-A-3 026 063), each working position therefore makes it possible to join by twisting two elementary wires (A, B) from two power sources (1,2). The wire (A) from the spool (1) passes through a turntable (3) or the like so as to form a balloon (4) inside which is arranged the power source (2) for the wire (B). The assembly of the two wires (A) and (B) is obtained by twisting at the meeting point (5), then the cable (6) formed is returned conventionally, for example on a winding system (7) not imparting additional torsion. The call of the two wires (A) and (B) constituting the cable (6), is given by the winding speed in (7). To equalize the tensions in order to have a balanced set, tensioning systems (8,9) are provided for each wires (A, B). The tensioner (8) adjusts the reserve length of the wire (A) around the plate (3) and acts as a shock absorber which absorbs jolts reel reel (1), which keeps a balloon (4) very regular.

The tensioner according to the invention is particularly suitable for be used to give tension to the wire (A) which passes inside the turntable (3) and forms the balloon (4).

The stranding machine equipped with tensioners (8) according to the invention is therefore consisting of a plurality of identical working positions arranged side by side side by side, the tensioners (8) to ensure the tension of the wire (A) coming from the support (1) carried by a creel arranged, in the case present, on the upper part of the machine, are mounted individually on a support plate (35) carried by said frame. The positioning of these tensioners is advantageously located on the machine frame at the level of the winding system, in front of it, the wire (B) being brought directly to the brake (9) located upstream of the wiring point (6) in the extension of the axis of the power source (2) of the wire (B).

As shown in Figures 2 and 3, in the embodiment illustrated substantially on scale 1, the tensioner (8) according to the invention has as an element to communicate the tension in the wire a pulley consisting of two cups (11,12) between which the wire passes (A), these cups being mounted on a hub (13) which is itself mounted free in rotation by means of bearings (14) the end of a tree (15). Said cups (11,12) are blocked on the hub via a nut-shaped assembly (16), which allows to adjust the pressure of the cups one against the other and consequently the tension that they apply to the wire. The wire (A) passes through space between the two cups and is maintained at their zone interpenetration, the wire envelope around said cups being determined by two guides (17,39) (shown only in FIG. 3), arranged respectively upstream and downstream of the support plane.

As shown in Figure 2, the hub (13) which supports the pulley has on its face opposite said pulleys, a crown (18) made of a ferro-magnetic material such as for example based on ferrite.

The means for braking the pulley are constituted by a plurality of permanent magnets (19) the number of two in this case, and in the form of pellets having a diameter of 15 mm. These magnets are mounted concentrically with the shaft (15) on a support (20), itself immobilized inside a case (21). The support (20) is locked by means of screws (22), is immobilized in rotation relative to the shaft (15), but is however free in translation relative to the latter.

According to the invention, the tensioner includes means allowing the spacing between the magnets (19) and the crown (18) carried by the pulley, this variation being between a minimum value of 1 mm, which avoids any risk interference due to geometric defects and maximum spacing, function of the power of the magnets, which in this case is 4 mm.

These means for adjusting include all first a first thrust assembly which tends to bring the support closer (20) magnets (19) of the crown. This movement is limited by one predetermined minimum value and is obtained, in this case, by a assembly in the form of a spring (23) arranged around the shaft (15) and in support, on the one hand on a fixed annular bearing (24) integral with the housing (21) and, on the other hand, on the rear face of a piston (32) integral with the shaft (15), which allows sliding of the housing (21) relative to the assembly (32-15).

As shown in Figure 2, the housing (21) is designed to so as to present on its rear face (33) a shoulder (34), which therefore makes it possible to produce a chamber (25) between the bottom of the case and the face (26) of the piston, the other face of the piston pressing against a shoulder provided on the shaft (15). Seals (30) and (31) are provided to ensure the sealing of the chamber (25). Inside this chamber (25), opens the inlet (36) of a compressed air supply. The tree (15) is fixedly mounted on a support (35) integral with the machine frame.

Thanks to such a design, it is therefore possible to be able to adjust the tension communicated by the pulley during the passage of the wire. In the representation illustrated in Figure 2, the different elements of the tensioner are shown in their position where the magnets (19) are at a distance predetermined minimum, i.e. in the present case of the order of one millimeter, of the crown (18) mounted on the hub (13) in the pulley (P). This position provides maximum tension on the wire. When you want to change the voltage value, you supply the chamber (25) in compressed air, which therefore tends to push back the piston (32) which exerts a counter-thrust on the spring (23), and therefore tends to move the housing (21) which carries the magnets relative to the shaft (15), in the direction going to the left if we consider figure 2, which will increase the spacing between said magnets and the crown (18). Consequently, the braking performed by the magnets tends to decrease.

As is apparent from Figure 4, it is possible through such design, to feed a plurality of tensioners from a single compressed air supply source (37), the air injection being regulated by a central pneumatic valve (38) and each deliverer (8) being connected by a conduit (36) to said power source.

In the example described, the displacement of the magnets relative to the pulley is obtained by moving the housing that supports the magnets on the shaft which is kept fixed on the machine. It could be considered to proceed in reverse, that is to say to mount the fixed box on the machine, which will then cause the pulley to move relative to said housing.

Claims (4)

1. A yarn tension device comprising :

   a pulley (P) mounted freely rotatably at the end of a shaft (15) carried by a housing (21), the yarn being in contact against the surface of said pulley ;

   means for braking said pulley (P) which consist of concentrically arranged permanent magnets (19) locked in terms of rotation relative to the shaft (15) and arranged opposite a ring (18) made of ferromagnetic material and mounted on the bearing (13) supporting the pulley (P);

   means making it possible to vary the spacing between the magnets (19) and the pulley-carrying bearing (13) by sliding one of these elements on the shaft (15), said means consisting in a first assembly (23,24) exerting a thrust tending to bring the support (20) of the magnets (19) nearer to the ring (18) associated with the pulley (P), to a predetermined minimum value ;

      characterized in that the means for adjusting the spacing between the magnets (19) and the pulley (P) to be braked comprise a second assembly (25,32) exerting a counterthrust of adjustable value, tending to move the magnets (19) away from the ring (18), said counterthrust means consisting of a compressed-air source (36) acting on the face (26) of a piston (32) which is mounted fixedly on the shaft (15) and bears against a bearing surface (29) of the latter and the other face (27) of which is subjected to the action of the first thrust means (23), compressed air being supplied simultaneously to all the tension devices which the machine comprises by means of a pneumatic line (37).
2. The device as claimed in claim 1, characterized in that the variation in the spacing between the magnets (19) and the ring (18) associated with the pulley (P) is obtained by displacing said magnets (19) longitudinally on the shaft (15) carrying the pulley, said shaft in that case being mounted fixedly on the frame of the machine.
3. The device as claimed in claim 1, characterized in that the variation in the spacing between the magnets (19) and the ring (18) associated with the pulley (P) is obtained by displacing the shaft (15) supporting said pulley, fastening to the frame of the machine being carried out by means of the housing (21) supporting the magnets (19).
4. A textile apparatus equipped with a tension device as claimed in one of claims 1 and 3, comprising a plurality of identical workstations, wherein the tension devices (8) are adjusted simultaneously on all the feeders of the machine which perform the same function.

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