EP1807563B1 - Yarn tensioning device - Google Patents

Description

The invention relates to a yarn braking device according to the preamble of claim 1 or 2.

In a known thread braking device ( EP 0 534 263 A ) forms a mechanical spring, the axial force generator and the radial centering device. The spring may be an annular radially oriented diaphragm, a radial spiral spring, a conical spiral spring, a cylindrical bellows, or, as in FIG Fig. 1 from EP 0 652 312 A shown to be a star-shaped spring arrangement of Schraubenzugfedern, each of which is mounted in the holder and the support ring body. A common problem of mechanical springs is a force development that is not uniform in the circumferential direction, aging, susceptibility to aggressive substances, and a tendency to collect lint. Another problem is that the mechanical spring at the same time centering in the radial direction and must apply the axial force to the brake body. This dual function represents a compromise between the development of the yielding axial force and the radial centering force, which can be critical in cases of extreme braking effects, ie when the friction center is extremely weak or if the braking effect is extremely strong, in each case the same reliable centering for the truncated cone Brake body is required. The adjustment range of the braking effect is limited by the nature of the mechanical spring, which means that the mechanical spring must be replaced with another as soon as a significant variation of the braking effect is needed. The braking effect is basically adjusted by the axial position of the holder in relation to the withdrawal end in order to more or less tension the spring. In the case of a very weak braking effect adjustment, the centering and the automatic resetting of the displacing brake body to a centered position may be insufficient, as in the case of an extremely strong braking effect adjustment. An optimal and consistent centering effect and the ability of the brake body, after a transverse displacement automatically return to a perfectly centered position on the discharge end of the storage body, namely a crucial prerequisite for proper braking function, since the large diameter end portion of the truncated cone mantle brake body only along the circumference the discharge end creates a uniform braking effect when its small diameter end is perfectly centered. Already only small misalignments result in permanent fluctuations of the braking effect and in undesirable variations of the thread tension. The as the clock from the storage body in the yarn braking device rotating like a clockwise thread is usually deflected in the support ring body and exerts on the brake body a circumferential force to the outside, which varies, eg at a node, and must be permanently absorbed and compensated by the centering device. Therefore, a properly working centering device for this type of yarn braking device has considerable functional importance.

It is off DE 195 31 579 A in a small-diameter circular disc brake, through which the thread passes only transversely, known to press the brake discs against each other by axially repelling permanent magnet rings. However, the functional requirements for centering are low because of the straight running thread, since the discs are mechanically centered and are inclined relative to each other in operation.

Furthermore, it is in controlled thread braking devices ( DE 198 39 272 A . EP 0 652 312 A . US 5 778 943 A ), the braking effect of which can either be modulated or completely switched off, is known to provide, in combination with a mechanical spring arrangement for a basic brake effect or a passive position, a magnetic axial force generator. The Axialkraftgenerator has at least one coil, which can be acted upon by electricity. When not energized, the axial force generator generates no force.

It is an object of the invention to provide a structurally simple and reliable, non-controlled yarn braking device of the type mentioned above, which allows a wide adjustment range for the braking effect and a good performance even in the case of extremely weak and extremely strong braking effect settings.

This object is achieved by the features of either claim 1 or claim 2.

In the solution according to claim 1, the pair of permanent magnets operate without contact and with a function which is not prone to aging, to aggressive means, to misalignments, not to uneven force development, and which ensures a wide range of adjustment for the braking effect. The pair of permanent magnets only has to generate the yielding axial force which determines the braking effect, while the required centering of the truncated cone mantle brake body is made at the small diameter end portion by the sliding guide system. This results in a constant centering effect for all settings of the braking effect. Both functions, i. the generation of the axial yielding force and the axial guidance can each be optimized for themselves, since these functions do not influence each other during operation of the yarn braking device. The problem of a lint collection and the negative influence of collected lint is eliminated. The structural design of the yarn braking device is simple and results in high reliability, since there are no vulnerable mechanical spring components.

In the solution according to claim 2, the permanent magnet pair simultaneously forms the Axialkraftgenerator and the centering device, ie, the small diameter end of the brake body is supported without contact only by magnetic forces, thereby acted upon axially against the storage body and radially from all sides by radial force components from the magnetic effect in the direction acted upon and centered to the axis of the thread braking device. Since a mechanical contact is missing, the yarn braking device is characterized by a quick and sensitive response. The at least one pair of permanent magnets forms in the thread braking device, so to speak, a virtual or magnetic spring. The respective inner permanent magnet could be provided directly integrated in the brake body or in the material of the brake body.

Since it is essential for the desired braking function that the precisely adjustable axially compliant force always acts correctly centered truncated cone mantle brake body against the withdrawal end, the permanent magnets in the magnet pair with optimal use of space can be arranged repellent or attractive each other.

For individual pairs, it should be at least three regularly distributed pairs.

A very uniform force development can be achieved with annular permanent magnets, which cooperate essentially on the same diameter or on different diameters.

Alternatively, for example, for reasons of weight, more than three circumferentially distributed permanent magnet pairs may each be used with individual permanent magnets, either an intended axial Gleitführungssystem constituting a Verdrehsicherungsmechanismus for the permanent magnets in the pairs, so that the permanent magnets are always aligned, or the individual Permanent magnets are designed and / or arranged so that they automatically generate an anti-rotation.

In a specific embodiment, in which the centering device simultaneously forms the anti-rotation mechanism, the support ring body is held in an outer ring carrying at least three circumferentially distributed, axial guide pins and either an annular permanent magnet or a plurality of individual permanent magnets. The holder has a ring portion which is provided with guide sleeve for the guide pins and having either an annular permanent magnet or individual permanent magnets in a multi-array. Alternatively, the guide pins could also be anchored in the ring area of the holder and for the guide sleeves may be arranged in the outer ring. The guide pins should pass through the guide sleeves with a slight slip fit.

In a further expedient embodiment, the outer ring is formed on its inside with a conical seat for the small diameter end of the brake body, and the support ring body is snapped as a snap ring in the outer ring to position the brake body in the seat. This has assembly advantages and allows, if necessary, a quick and convenient replacement of the brake body.

In a further expedient embodiment of the support ring body is set in a small diameter ring edge of a generally conical cage, which is equipped at its large diameter end portion with either one or more individual permanent magnets and the brake body with radial distance. The cage is loosely inserted into a support ring having either the other annular or multiple discrete permanent magnets and circumferentially distributed axial support legs, the inner sides of which define axial sliding guide surfaces for a mating surface on the outer periphery of the large diameter end portion. In the case of annular permanent magnets no anti-rotation mechanism is needed. By contrast, an anti-rotation mechanism may be expedient for individual permanent magnet pairs, for example between the cage and the support ring or between the sliding guide surfaces and the counter guide surface. The counter-guide surface may be concavely rounded in an axial section of the cage, so that an axially displaceable universal or ball joint is formed between the counter guide surface and the axial guide surfaces on the holder feet, which allows the working movements of the radially deformable brake body without influence and yet the small diameter end of the Brake body centered properly.

For ease of mounting, the holder feet are snap-action holders with inherent predetermined bending elasticity for snap-fastening to the ring portion of the holder. The cage and the holder feet have enough gaps so that no fluff accumulates there, or at any time for cleaning or for inspection.

For ease of assembly, the support ring body should be formed with an outside seat for the small diameter end portion of the brake body, the seat being bounded on one side by a shoulder so that the support ring body can snap into the annular edge of the cage to position the brake body. The seat could be partially or entirely formed in the rim of the cage.

In a particularly advantageous embodiment, which is operated without a mechanical axial Gleitführungssystem, is the outer single or annular permanent magnet arranged on a larger diameter relative to the axis than the inner single or annular permanent magnet. The permanent magnets of the pair or of the pairs, for example each repelling permanent magnet, cooperate such that obliquely directed forces are generated on the axis whose radial force components are used for centering and their axial force components for generating the axial contact force. The art of placing the outer permanent magnet (s) on a larger diameter than the inner permanent magnet (s) results in the inner permanent magnet being exposed to an increasing outward radial force component when displaced outwardly from the axis and sustainably back toward the axis is pressed. That is, the maximum, centering radial force component is built up only when the inner permanent magnet seeks to shift outward. In this way, the one or more inner permanent magnets are trapped in the magnetic fields of the or the outer permanent magnet, provided that the brake body rests with axial force on the withdrawal edge of the storage body. The small-diameter end of the brake body also remains centered properly under the radially outward acting forces of, for example, the support ring body deflected thread and passage of a node.

In a preferred embodiment, the mutually facing repelling surfaces of the repulsive permanent magnets of the pair are inclined obliquely to the axis, preferably even conical, and at least substantially parallel to each other. Already by the formation of the permanent magnets, the radial and axial force components are generated.

In an expedient embodiment with annular permanent magnets, these are conical rings with a rectangular or trapezoidal cross-section. Solely by this form of permanent magnets, the magnetic direction of action over the circumference is inclined evenly inclined to the axis of the yarn braking device, so that the multiple effect of the radial force components, the axial force components and the deflection of the small diameter end outwardly increasing, opposite radial force components occurs.

In an expedient embodiment with distributed over the circumference of individual permanent magnets in several pairs, the outer individual permanent magnets are offset relative to the inner individual permanent magnets in the circumferential direction each gap. Since each inner single permanent magnet is simultaneously acted upon by the magnetic forces of two outer individual permanent magnets from different directions, the cooperating permanent magnets form a contact-free rotation lock automatically. Again, the inner individual permanent magnets should be arranged on a smaller diameter than the outer individual permanent magnets for centering and resetting.

In an expedient embodiment, the support ring body carries the individual or annular inner permanent magnets. A on the small diameter end of the brake body cross-conical support cage, which is preferably releasably fixed to the holder carries on its support ring, the individual or the annular outer permanent magnet. This solution is advantageous manufacturing technology and assembly technology.

In a further expedient embodiment, a cylindrical extension of the truncated cone shell is integrally formed on the small diameter end of the brake body. This measure avoids local overstressing of the acted upon by the axial force small diameter end and allows easy installation, for example by the brake body is only loosely inserted into the support ring body.

In a further expedient embodiment, the support ring body has an approximately cylindrical extension which passes through the support ring of the support cage, without touching it. This measure stiffens the support ring body and makes it possible to limit its displacement movement in an emergency with extremely laterally displaced brake body. During normal operation of the yarn braking device, however, no contact occurs between the extension and the support ring.

For the aforementioned reasons, it is important that between the support ring body and the support ring of the support cage, an intermediate distance in the direction of magnet action is generated at least with the size of the air gap between the permanent magnets.

Finally, it is advantageous from a handling point of view to equip the cylindrical extension of the support ring body at its end protruding beyond the support ring of the support cage with an outwardly directed catch projection, for example an annular flange, whose outer diameter is slightly larger than the inner diameter of the support ring. During assembly, the support ring body is first inserted against a resistance in the support ring. During normal operation of the yarn braking device, that is, as soon as the brake body is attached to the storage body, the catch projection on the support ring is no longer engaged. When mounting or transport, however, prevents the catch projection by its attack on the support ring, that the support ring body with the brake body falls out of the support ring.

The magnitude of the axial force of the axial force generator is set by the axial position of the holder relative to the discharge end of the storage body. In order to be able to sensitively and remotely control the axial force generated between the permanent magnets without manual intervention on the adjusting device of the holder, in an expedient embodiment, at least one coil optionally acted upon by current is functional, ie assigned to a magnetic cooperation, one of the permanent magnets of the axial force generator to generate a superposition of the axial force auxiliary magnetic force. The auxiliary magnetic force increases or reduces the axial force to the desired extent. One of the already provided for supporting the brake body permanent magnet is used as it were as a fitting of an optionally controlled electromagnet. Since the permanent magnets generate a relatively strong axial force, a not particularly strong coil and / or a moderate current may be sufficient to adjust a possibly only slight increase or decrease in the axial force. The effect of the coil or coils can be enhanced by appropriately placed iron, preferably soft iron. This embodiment is suitable for a knitting machine, in particular a circular knitting machine in which often many yarn feeding devices are mounted and changes in operation Knitting quality can occur, which can be compensated by a change in the braking effect or the knitting thread tension. By means of the coils in the braking devices, the axial forces can then be changed independently of the value of the respective axial force in a group or in all yarn feeding devices and thus substantially simultaneously the knitting yarn tensions are raised or reduced by substantially the same amount.

In a further embodiment, the coil is arranged stationarily outside the brake body and assigned to the permanent magnet supported on the brake body of the axial force generator. Here the permanent magnet, which is already present in the axial force generator, is used for this additional function without additional effort.

In a further embodiment, the coil is supported on the brake body and functionally associated with the stationary outside of the brake body arranged permanent magnet. The coil is light, so that the mass of the brake body remains low. The arranged outside the brake body permanent magnet is already part of the Axialkraftgenerators and usable for this additional function without additional construction costs.

In a yarn braking device, the brake body is housed on a support ring body in a support cage, the coil is advantageously arranged in the support cage or on the support ring body. Thanks to this placement, the coil is optimally close to the permanent magnet.

Fig. 1

eine Seitenansicht, teilweise im Schnitt, einer Fadenbremsvorrichtung,

Fig. 2

eine Schnittansicht in der Schnittebene II - II in Fig. 1,

Fig. 3

eine Schnittansicht in der Ebene III - III in Fig. 2,

Fig. 4

eine Perspektivansicht der Fadenbremsvorrichtung der Fig. 1 - 3,

Fig. 5

einen Teil einer Achsschnittansicht einer anderen Ausführungsform der Fadenbremsvorrichtung,

Fig. 6

eine Seitenansicht eines Details der Fadenbremsvorrichtung von Fig. 5, und

Fig. 7

eine Seitenansicht eines weiteren Details der Fadenbremsvorrichtung von Fig. 5,

Fig. 8

einen Achsschnitt einer weiteren Ausführungsform einer Fadenbremsvorrichtung,

Fig. 9

ein vergrößertes Detail aus Fig. 8, in einem Achsschnitt,

Fig. 10

eine Detailvariante, im Schnitt, ähnlich Fig. 9,

Fig. 11

einen Achsschnitt eines in Fig. 8 durch einen Kreis hervorgehobenen Details,

Fig. 12

eine perspektivische Explosionsdarstellung der Hauptkomponenten der Fadenbremsvorrichtung von Fig. 8,

Fig. 13

eine andere Perspektivansicht einer Komponente aus Fig. 12,

Fig. 14

einen schematischen Achsschnitt einer weiteren Ausführungsform einer Fadenbremsvorrichtung,

Fig. 15

einen Achsschnitt einer weiteren Ausführungsform einer Fadenbremsvorrichtung,

Fig. 16

eine Detailvariante ähnlich den Fig. 9 und 10, und

Fig. 17

schematisch eine Detailvariante einer weiteren Ausführungsform einer Fadenbremsvorrichtung.

With reference to the drawings, embodiments of the subject invention will be explained. Show it:

Fig. 1

a side view, partially in section, a yarn braking device,

Fig. 2

a sectional view in the section plane II - II in Fig. 1 .

Fig. 3

a sectional view in the plane III - III in Fig. 2 .

Fig. 4

a perspective view of the yarn braking device of Fig. 1-3 .

Fig. 5

a part of an axial sectional view of another embodiment of the yarn braking device,

Fig. 6

a side view of a detail of the yarn braking device of Fig. 5 , and

Fig. 7

a side view of another detail of the yarn braking device of Fig. 5 .

Fig. 8

an axial section of another embodiment of a yarn braking device,

Fig. 9

an enlarged detail Fig. 8 in an Axis cut,

Fig. 10

a detail variant, on average, similar Fig. 9 .

Fig. 11

an axial section of an in Fig. 8 details highlighted by a circle,

Fig. 12

an exploded perspective view of the main components of the yarn braking device of Fig. 8 .

Fig. 13

another perspective view of a component Fig. 12 .

Fig. 14

a schematic axial section of another embodiment of a yarn braking device,

Fig. 15

an axial section of another embodiment of a yarn braking device,

Fig. 16

a detail variant similar to the FIGS. 9 and 10 , and

Fig. 17

schematically a detail variant of another embodiment of a yarn braking device.

A first, in Fig. 4 shown in perspective view of an uncontrolled yarn braking device B is based on the Fig. 1 to 4 explained. The thread braking device B is in a yarn feeding device F ( Fig. 1 ), which has a drum-shaped, stationary storage body 1 with a rounded discharge end 2 and an axis X, which is also the axis of the yarn braking device B. In the yarn braking device B, a brake body K in the shape of a truncated cone 3 (with a straight line as the generator) is provided, which is slipped with its large-diameter end 4 on the withdrawal end 2 and is pressed against it by an axial yielding force, which for a deduction from - And while clockwise circulating thread defines the braking effect in the contact area between the inside of the truncated cone shell 3 and the withdrawal end 2. The brake body K is for example made of a plastic with or without reinforcement, made of metal or of a mesh or mesh fabric. Optionally, in the braking zone, an inner, circumferential brake pad made of wear-resistant material is provided, although the inner surface of the brake body K is also directly usable for braking. The yarn braking body K is axially relatively stiff, however, radially deformed slightly so that it fits snugly on the withdrawal end 2 and with the forcibly forcibly circulating thread can form a trailing wave or let nodes pass ..

A small diameter end 5 of the yarn braking body K is here supported on a support ring body 8, which on the inside has a friction-resistant and wear-resistant surface for contact with the yarn to be deflected there and is snapped inside as a snap ring in an outer ring 7. The outer ring 7 (or the support ring body 8) has a tapered seat 6 for the small diameter end 5 of the yarn braking body K, which is loosely positioned interchangeable only by the snap action between the support ring 8 and the outer ring 7.

At an axial distance from the outer ring 7, a not shown in detail yarn feeding device parallel to the axis X adjustable holder 10 is stationarily supported, which has a ring area 11 having a passage opening for the thread to be withdrawn. Between the holder 10 and the support ring body 8, a centering device C is provided, which centers the small diameter end 5 of the yarn braking body on the axis X and, in this embodiment, simultaneously an anti-rotation mechanism, which limits a relative rotation between the outer ring 7 and the holder 10 or prevented. Furthermore, Fig. 3 ) between the outer ring 7 and the holder 10, an axial force generator P is provided, which generates yielding axial force between the holder 10 and the yarn braking body K for the braking effect.

The centering device C consists in the Fig. 1 to 4 from several, distributed in the circumferential direction, here anchored in the outer ring 7, axial guide pins 9, which pass through arranged in the annular region 11 of the holder 10 guide sleeves 12 with a slight push fit. Advantageously, a very small radial play is provided between the guide pins 9 and the guide sleeves 12. The positions of the guide pins 9 and the guide sleeves 12 could also be reversed.

The axial force generator P is formed by repulsive permanent magnets 13, 14 in this embodiment, which are aligned in pairs axially. In pockets 16 of the outer ring 7 individual permanent magnets 13 are contained, while in axially aligned pockets 15 on the ring portion 11 individual permanent magnets 14 are supported.

The adjustment of the brake body K on the withdrawal end 2 pressing axial force between the permanent magnets 13, 14 is made by the axial positioning of the holder 10 relative to the withdrawal end 2.

In the embodiment shown, three guide pins 9 are provided at equal intervals (180 °) and structurally and functionally separated from the permanent magnet pairs. Furthermore, twelve regularly distributed (30 °) arranged permanent magnet pairs 13, 14 are provided. The number of guide pins 9 and / or the permanent magnet pairs could also be chosen differently.

Although this in the Fig. 1 to 4 is not shown, instead of the plurality of pairs of permanent magnets 13, 14, two annular, one-piece permanent magnets, for example, from a magnetizable, bound by plastic mass may be provided. In a further, not shown modification of the embodiment of Fig. 1 to 4 For example, it would be possible to use magnet pairs that attract each other, for example, by attaching a ring which is analogous to the outer ring 7 to the outer ring 7 on the ends of the guide pins 9 extended beyond the holder 10 and fitting it with pulling permanent magnets. For example, neodymium or ferrite permanent magnets are particularly suitable.

In Fig. 1 is a detail variant of the yarn braking device indicated by dashed lines. The permanent magnet 13, which transmit the axial force of the Axialkraftgenerators P on the brake body K, outside at least one selectively acted upon by current coil 39 is magnetically functionally assigned so that when energizing the coil 39, a magnetic force 41 at least substantially the same or opposite effective direction as the Axialkraft is generated, with which the value of the axial force is increased or decreased. The coil 39 is placed, for example, on a carrier 40 arranged on the annular region 11.

When the yarn braking device B in the Fig. 5 to 7 lacks the embodiment of the Fig. 1 to 4 an anti-rotation mechanism. The holder 10 is positioned with its annular region 11 'very close to the withdrawal end 2 of the storage body 1 on the yarn feeding device (not shown). As a result, mounting space is saved beyond the possibly provided.

The brake body K is positioned with its small diameter end 5 in a here in the support ring 8 shaped conical seat 6. The seat 6 is delimited by a shoulder 8a against which a ring edge 17 of a generally conical cage 18, snapped into the seat 6 while fixing the small-diameter end 5, is supported. The cage 18 has a cone angle which is greater than the cone angle of the brake body K and a plurality of spokes 19 emanating from the annular rim 17 leading to an annular, large-diameter end region 20. The brake body K is sunk in the cage 18, so to speak, at least with part of its longitudinal extent.

The large-diameter end portion 20 of the cage 18 includes an annular permanent magnet 13 'which is axially aligned by the centering device C to another annular permanent magnet 14' which is held in a support ring 21. The support ring 21 has outside axial and at regular intervals distributed holder feet 22 which extend in the direction of the large diameter end 4 of the brake body and formed as snap holder with inherent, predetermined bending elasticity and snapped into the annular region 11 'of the holder 10. On the inner walls of the holder feet 22 axial guide surfaces 23 are provided for a provided on the outer periphery of the large diameter end portion 24, for example, circulating counter guide surface 24. The guide surfaces 23, 24 form the centering device C. The counter guide surface 24 is rounded, for example, as shown, to fulfill the function of an axially movable universal or ball joint for centering the brake body K.

In a modified embodiment, not shown Fig. 5 to 7 could instead of the two annular permanent magnets 13 ', 14', similar to in Fig. 2 , a plurality of individual permanent magnet pairs are arranged. Then it is expedient to integrate in the centering device C and a Verdrehsicherungsmechanismus, for example, by a form-fitting cooperation in the circumferential direction between the guide surfaces 24, 23rd

In the embodiment in the Fig. 5 to 7 are provided repelling permanent magnets. In a modification, not shown, attracting permanent magnets could be used, for example, in which a permanent magnet ring at the upper end of the support legs 22 is set, which pulls the arranged in the large-diameter end portion 20 annular permanent magnet upwards. The cage 18 is loosely inserted with the brake body K in the defined by the holder feet 22 and the support ring 21 structure. An exchange of the brake body K is possible after loosening the holder feet 22 from the ring portion 11 ', either the brake body K changed together with the cage 18 as a unit or only the brake body K after releasing the support ring 8 from the ring edge 17 is replaced.

The spokes 19 ( Fig. 6 ) of the cage 18 permit visual inspection or cleaning of the internal components at all times, also because the holder feet 22 leave large spaces in between. Apart from the permanent magnets, all components of the yarn braking device can be plastic molded parts. This also applies to the embodiment of Fig. 1 to 4 ,

Dashed is in Fig. 5 a detail variant of the yarn braking device B indicated. At least one coil 39 is arranged in the holding feet 22 such that it interacts magnetically with the permanent magnet 13 'when the current is applied, and the axial force generated between the permanent magnets 13', 14 'superimposes an auxiliary magnetic force of the same or opposite effective direction. In Fig. 5 is the coil 39 is arranged so that it energized, for example, generates an axial force increasing auxiliary magnetic force 41.

In the embodiments of the 8 to 17 For example, the axial force generator P and the centering device C are simultaneously formed without contact by the pairs of permanent magnets by the permanent magnets (either two rings or a plurality of circumferentially distributed pairs of individual permanent magnets) cooperating with an obliquely directed to the axis X magnetic effect. Preferably, each repelling permanent magnets are used, although (not shown) with an appropriate arrangement and attracting permanent magnets could be used.

The axial cut in Fig. 8 shows the operative position of the yarn braking device B with the yield point 2 of the storage body 1 axially resiliently pressed Fadenbremskörper K. The small diameter end of the yarn braking body K is optionally. Here designed with a cylindrical extension support ring 8 is provided, the outside bears the annular permanent magnet 13 ' on which a held in a support cage annular permanent magnet 14 'is substantially axially aligned. As based on the Fig. 9, 10, 16 is explained, the here repelling each other permanent magnets 13 ', 14' are arranged and / or formed such that their magnetic effect directed obliquely to the axis X of the yarn braking device B. is and thereby radial force components are generated inwardly and axial force components in the direction of the storage body. The permanent magnet 13 'could be arranged directly on the brake body K or be integrated in its material (eg magnetic plastic).

The in Fig. 9 only partially shown support cage 26 (with spaces between spokes 27) has at its smaller end a closed support ring 37, in which the annular permanent magnet 14 'is positioned as a cone ring with a trapezoidal cross-section so that its flat or conical repelling surface (the wider base of the trapezoid) is inclined at an angle, for example, 45 ° relative to the axis. On the annular permanent magnet 14 'is substantially axially the likewise annular permanent magnet 13' aligned, which is a cone ring with a trapezoidal cross section and a flat or conical repelling surface on the wider base of the trapezoid. The permanent magnet 13 'is fixed in the support ring body 8, the cylindrical extension 29 engages without contact by the support ring 37. Between the repelling surfaces of the permanent magnets 13, 14 is an air gap. The radial distance between the extension 29 and the support ring 37 is approximately as large as the width of the air gap. At the free end of the extension 29, a catch projection 38 is formed, for example, a hook-like outer flange whose outer diameter is slightly larger than the inner diameter of the support ring 37. The support ring 8 is made of elastic material, such as plastic. The elasticity of the material makes it possible to introduce the catch projection 38 against the initial resistance in the support ring 37. However, the support ring 8 can be pulled out again only with emphasis, so that it can not fall out of the support ring 37 and the support cage 26 by itself.

The brake body K is provided with a cylindrical extension 5 'at its small-diameter end 5 via an inwardly guided, rounded shoulder, so that a rounded thread deflection shoulder 5 "is formed in the support ring body 8 Seat 30 is formed for the yarn brake body K. The yarn brake body K is either only loosely inserted into the support ring body 8, so that when a required replacement of the brake body K of the support ring 8 can continue to be used, or optionally adhered, for example glued.

Due to the obliquely inclined, mutually substantially parallel repelling surfaces of both permanent magnets 13 ', 14', the repulsive force acts obliquely down to the right X axis, so that from the magnetic effect, the axial force for pressing the brake body K against the withdrawal edge 2 and at the same time the radial force components for centering the small diameter end 5 of the brake body K are generated without mechanical contact between the support ring 8 and the support ring 37 occurs.

Dashed is in Fig. 9 indicated that in the small diameter end of the support cage 26 two optionally acted upon by current coils 39 are functionally associated with the permanent magnet 13 'so that they generate an auxiliary magnetic force at the permanent magnet 13' when current is applied. Alternatively, the coil 39 'could be placed on the brake body K or the support ring body 8 and functionally associated with the stationary permanent magnet 14' to generate the auxiliary magnetic force.

Since the yarn braking device B does not require a mechanical centering or axial guiding device, if the permanent magnets 13 ', 14' also form the centering device G, is in the embodiment in Fig. 10 the support ring 8 without cylindrical extension 29 as in Fig. 9 educated. As a result, the moving masses are reduced. The support ring body 8 can form the shoulder region 5 "for deflecting the thread The brake body K is inserted with the small diameter end 5 directly into the seat 30 of the support ring body 8, possibly only loosely or adhesively bonded the same diameter d, on which, so to speak, the magnetic centers of force of both permanent magnets 14 ', 13' lie.

Fig. 11 illustrates the releasable fixing of the support cage 26 in an annular body 11 of the holder 10, not shown. The annular body 11 has a flange 32 with insertion 33 for locking tongues 35 of the support cage 26. The locking tongues 35 are easily releasably hooked behind a shoulder.

The exploded view in Fig. 12 shows the arrangement of the main components of the yarn braking device about the 8 and 9 with the support cage 26 with its memory 27, the latching hook 35 and the support ring 37, the support ring body 8 with its extension 29 and finally the brake body K with the cylindrical extension 5 'of Fig. 9 , The inner annular permanent magnet 13 'is fixed to a shoulder region of the support ring body 8, for example glued or snapped. Fig. 13 illustrates the positioning of the outer annular permanent magnet 14 'in the inside of the support ring 37 of the support cage 26. Also, the permanent magnet 14' is either glued or snapped. Since the support ring 8 and the support cage 26 may be injection molded plastic, the permanent magnets 13 ', 14' could also be overmolded and thereby positioned. The coil 39 (if necessary, a plurality of coils) may be placed inside the support cage 26.

Fig. 16 shows a modified detail variant of the yarn braking device of FIGS. 8, 9 and 10 , The outer annular permanent magnet 14 'has a larger diameter d2, the inner annular permanent magnet 13', however, a smaller diameter d1. The further education corresponds to the basis of the FIGS. 9 and 10 explained. The permanent magnets 13 ', 14' repel each other. Since the outer permanent magnet 14 'acts on the d1 larger diameter d2, the radial component of the repulsive force increases when the small-diameter end 5 of the brake body K in Fig. 16 For example, to shift upward, so that an enlarged radial area arises, within which the inner permanent magnet 13 is pushed back and centered by the outer permanent magnet 14 ', and the stronger, the stronger the inner permanent magnet 13' is deflected upward.

At the in Fig. 14 shown embodiment of the yarn braking device B are two annular permanent magnets 13 ', 14' (repelling permanent magnets) provided as conical rings with rectangular cross-section, which simultaneously constitute the axial force generator P and the centering device C.

In the embodiment in Fig. 15 are also two annular (cone rings) permanent magnets 13 ', 14' provided with a rectangular cross-section (repelling permanent magnets), wherein the outer permanent magnet 14 'on a larger diameter d2, whereas the inner permanent magnet 13' are arranged on a smaller diameter d1, as based Fig. 16 FIG. 11 illustrates a larger radial area within which the inner permanent magnet 13 'is returned from the outer permanent magnet 14' to the centered position as it is displaced with increasing force.

The principle of the magnetic effect directed obliquely to the axis X of the yarn braking device can be realized not only with annular permanent magnets, but as in FIG Fig. 17 also with individual permanent magnets 13, 14, which are for example cylindrical disks or cuboid blocks. The permanent magnets 13, 14 are each distributed in pairs around the circumference of the yarn braking device, wherein the inner individual permanent magnets 13 are connected to the brake body and the outer individual permanent magnets 14, for example with the support ring 37 or other holder. The permanent magnets 13, 14 are aligned with each other so that the magnetic effect is directed obliquely, for example, to an intersection 36, to the axis X, to generate the axial force and at the same time the radial force components. The permanent magnets 14 are expediently arranged on a larger diameter d2 than the inner permanent magnets 13. Thus, the permanent magnets 13, 14 do not rotate relative to each other about the axis X, the permanent magnets 13, 14 in the circumferential direction relative to each other set to gap, ie, each inner permanent magnet 13 is simultaneously applied by two outer permanent magnet 14 magnetically obliquely with force. A gap between the outer permanent magnets 14 is indicated for example at 34. Then the inner single permanent magnet 13 is aligned. The directions of action of the outer and inner permanent magnets 13, 14 need not necessarily be in the same intersection point 36 on the axis X, but it could affect the directions of action of the outer repulsive permanent magnet 14 also left more than at the intersection 36 on the axis X. Thanks to this arrangement, the cooperating permanent magnets 13, 14, as soon as the brake body to the Memory body 1 is pressed, the axial force generator P and the centering device C, without any mechanical contact. The permanent magnets 13 could be arranged directly on the brake body K or even integrated in its material.

The coil or coils 39, 39 'are suitably connected to a Stromsteuer- and -einstellvorrichtung. To improve the effect of the coil, iron material, in particular soft iron, may be placed in the vicinity thereof. For example, in a circular knitting machine many yarn feeding devices with such yarn braking devices B are present, then the coils 39, 39 'expediently from a central Stromsteuer- and -einstelleinrichtung off to the axial forces in the yarn braking devices of these yarn feeding devices together and regardless of the value of the respective axial force for example, to change the same measure. In this way, a looming deterioration in the quality of the knitted fabric caused by a drainage of the knitting thread tension can be conveniently compensated.

Claims (23)

1. Yarn tensioning device (B) for a yarn feeding device (F), the yarn tensioning device (B) comprising an axially stiff, radially deformable braking body (K) with the shape of a frustocone coat (3), the large diameter end (4) of the braking body (K) coaxially set over a rounded withdrawal end (2) of a drum-shaped storage body (1) and being pressed with the small diameter end (5) resiliently against the withdrawal end (2) by an axial force defining the tensioning effect between the braking body (K) and the withdrawal end (2), an axial force generator (P) having an axial acting direction, and a centring device (C) having a radial acting direction, respectively, between a stationary holder (10) and the braking body (K), characterized in that the axial force generator (P) is constituted by at least one pair of permanent magnets, the permanent magnets (13, 14, 13', 14') being aligned axially against each other with an intermediate gap by the centring device (C), and that the centring device (C) is separated structurally and functionally from the pair of permanent magnets and comprises an axial sliding guiding system (9,12, 24, 23).
2. Yarn tensioning device (B) for a yarn feeding device (F), the yarn tensioning device (B) comprising an axially stiff, radially deformable braking body (K) with the shape of a frustocone coat (3), the large diameter end (4) of the braking body (K) coaxially set over a rounded withdrawal end (2) of a drum-shaped storage body (1) and being pressed resiliently with the small diameter end (5) against the withdrawal end (2) by an axial force defining the tensioning effect between the braking body (K) and the withdrawal end (2), an axial force generator (P) having an axial acting direction, and a centring device (C) having a radial acting direction, respectively, between a stationary holder (10) and the braking body (K), characterized in that the axial force generator (P) and the centring device (C) at the same time are constituted by at least one pair of permanent magnets, of which one inner permanent magnet (13, 13') is supported at the holder (10) while the other outer permanent magnet (14, 14') of the pair is supported at the braking body (K), and that the permanent magnets of the pair are aligned against each other with an intermediate gap and with an acting direction of the magnet forces inclined obliquely towards the axis (X) of the yarn tensioning device (B), the permanent magnets of the pair generating both axial force components and radial force components, respectively.
3. Yarn tensioning device as in claim 1 or claim 2, characterized in that the pair of permanent magnets comprises respectively initially repelling or attracting permanent magnets (13, 14, 13', 14').
4. Yarn tensioning device as in claim 3, characterized in that more than three pairs of the permanent magnets are distributed in circumferential direction.
5. Yarn tensioning device as in claim 1 or claim 2, characterized in that the permanent magnets (13', 14') of each pair of permanent magnets are ring-shaped.
6. Yarn tensioning device as in claim 1, characterized in that in the case of pairs of single permanent magnets (13,14) which are distributed in circumferential direction the axial sliding guiding system (9,12) is consisting an anti-rotation protection mechanism for the permanent magnets of each pair.
7. Yarn tensioning device as in at least one of the preceding claims, characterized in that a support ring body (8) holding the small diameter end (5) of the braking body (K) is inserted into an outer ring (7), that the outer ring (7) carries at least three axial guiding pins (9) distributed in circumferential direction and either a ring-shaped permanent magnet (13') or several single permanent magnets (14), respectively, and that the holder (10) comprises a ring section (11) which is equipped with guiding sleeves (12) for the guiding pins (9) and either with a ring-shaped permanent magnet (14') or with several single permanent magnets (14), respectively.
8. Yarn tensioning device as in claim 7, characterized in that the outer ring (7) includes an inner conical seat (6) for the small diameter end (5) of the braking body (K), and that the support ring body (8) is a snap ring adapted to be snapped into the inner side of the outer ring (7) for positioning the braking body (K) in the inner-conical seat (6).
9. Yarn tensioning device as in claim 7, characterized in that the support ring body (8) is secured within a small diameter ring edge (17) of a generally conical cage (18), that the cage is equipped in a large diameter end region (20) either with a ring-shaped permanent magnet (13') or with several single permanent magnets (13), respectively, that the cage is surrounding the braking body (K) with a radial intermediate space, and that the cage (18) is loosely inserted into a support ring (21) containing either another ring-shaped permanent magnet (14') or several single permanent magnets (14), respectively, and comprising axial, preferably elastically bendable, holder feet (22) which are distributed in circumferential direction, inner sides of the holder feet (22) defining sliding guiding surfaces (23) for a counter guiding surface (24) provided at the outer periphery of the large diameter end region (20) of the cage (18).
10. Yarn tensioning device as in claim 9, characterized in that the support ring body (8) is formed at the outer side with a seat (8) for the small diameter end (5) of the braking body (K), that the seat (6) is bounded at one end by a shoulder (8a), and that the support ring body (8) is snapped into the ring edge (17) of the cage (18) for positioning the small diameter end (5) of the braking body (K) in the seat (6).
11. Yarn tensioning device as in claim 2, characterized in that related to the axis (X) either the single or the ring-shaped outer permanent magnet (14,14') is provided on a larger diameter (d2) than the single or the ring-shaped inner permanent magnet (13, 13').
12. Yarn tensioning device as in claim 2, characterized in that the permanent magnet (13, 14,13', 14') of the pair have repelling surfaces which are facing towards each other, that the repelling surfaces are inclined towards the axis (X), preferably both are conical, and that the repelling surfaces are substantially parallel to each other.
13. Yarn tensioning device as in claim 2, characterized in that the ring-shaped permanent magnets (13', 14') of the pair are conical rings having rectangular cross-section or trapezoidal cross-section.
14. Yarn tensioning device as in claim 11, characterized in that the single permanent magnets (13, 14) of the several pairs are offset in circumferential direction in relation to each other such that one permanent magnet of a pair is directed towards the gap between two adjacent oppositely arranged permanent magnets.
15. Yarn tensioning device as in claim 2, characterized in that the single inner permanent magnets (13) or the ring-shaped inner permanent magnet (13') are/is carried by a support ring body (8), and that a conical support cage (26) is secured, preferably detachably, at the holder (10), such that the support cage (26) surrounds the small diameter end (5) of the braking body (K), and that the support cage (26) is provided with a carrying ring (37) at its small diameter end which carrying ring (37) carries each single outer permanent magnet (14) or the ring-shaped outer permanent magnet (14'), respectively.
16. Yarn tensioning device as in claim 2, characterized in that a cylindrical extension (5') is formed at the small diameter end (5) on the frustocone coat of the braking body (K).
17. Yarn tensioning device as in claim 15, characterized in that the support ring body (8) has an essentially cylindrical extension (29).
18. Yarn tensioning device as in claim 15, characterized in that an intermediate distance at least of the size of the intermediate distance between the permanent magnets (13, 14, 13', 14') of the pair is provided between the support ring body (8) and the carrying ring (37).
19. Yarn tensioning device as in claim 17, characterized in that the cylindrical extension (29) of the support ring body (8) has an outwardly directed catching projection (38) at the end protruding beyond the carrying ring (27).
20. Yarn tensioning device as in claim 1 or claim 2, characterized in that at least one coil (39, 39') is provided which can be selectively supplied with electric current and which is functionally associated to one of the permanent magnets (13, 14, 13', 14') of the axial force generator (P), and that the coil is adapted to generate an auxiliary magnet force (41) superimposed to the axial force of the axial force generator (P) either acting essentially in the same direction as the axial force or counter to the direction of the axial force.
21. Yarn tensioning device as in claim 20, characterized in that the coil (39) is arranged stationarily outside of the braking body (K) and is associated either to the permanent magnet (13, 13') supported at the braking body (K) or to the ring element (42'),
22. Yarn tensioning device as in claim 20, characterized in that the coil (39') is supported at the braking body (K) and is functionally associated to the permanent magnet (14, 14') which is arranged stationarily outside of the braking body (K).
23. Yarn tensioning device as in claim 20, characterized In that the coil (39') is arranged either within the support cage (20) or at the support ring body (8), respectively.

Images