Abstract: Yarn feeder including a body carrying a drum on which turns of yarn from a spool are wound; a tension sensor for measuring exiting yarn tension value, a braking member including a first permanent magnet and a fixed second magnet, regulator for varying action the second magnet exerts on the first permanent magnet, and a control unit to control the regulator. The first magnet is annular and movable parallel to the axis of the drum and along it between a first position where the first permanent magnet enables pressing the yarn against a counteracting element fixed to the drum and a second position where this effect does not occur. The control unit receives tension values measured by the tension sensor, comparing them with a predetermined value and intervening in real time on the regulator to adjust tension value to predetermined value when these two values do not coincide.

Abstract: A drum has a plurality of yarn loops wound thereon which are to be unwound upon request from a downstream machine. A weft-braking device provided with a braking member having a circular profile is biased against a delivery edge of the drum by driving elements. The yarn is adapted to run between the delivery edge and the braking member to receive a braking action by friction from them. The driving elements comprise at least one piezoelectric actuator which is deformable in response to a voltage applied thereto and has a movable operative end which is operatively connected to the braking member and a stationary operative end which is anchored to a stationary support.

Abstract: A yarn braking device includes a braking body with the shape of a frustocone coat. The braking body is put over a rounded withdrawal end of a storage body and is pressed from the small diameter end by a resilient axial force against the withdrawal end. The axial force defines the braking effect between the braking body and the withdrawal end. Between a stationary holder and the braking body an axial force generator and a centering device acting in radial direction are provided. The axial force generator is formed by at least one pair of permanent magnets. The permanent magnets are axially aligned by the centering devices with an intermediate gap. The centering device neither is an axial sliding guiding system structurally and functionally separated from the pair of permanent magnets, or is formed free of contact directly by the pair of permanent magnets, respectively.

Abstract: Yarn loops are unwound from a stationary weft-winding drum during a weft insertion. A weft-braking device locks the yarn unwinding from the drum at the end of the insertion, and comprises at least one braking member which is arranged by side of the drum near its delivery end and is movable under control of an actuator between a resting position in which it is spaced from the outer surface of the drum and does not interfere with the unwinding yarn, and an operative position in which it engages the outer surface of the drum and cooperates with it to brake the yarn.

Abstract: A control unit for yarn-braking devices in weft feeders for looms, in which the yarn unwinding from the feeder is pressed between a drum and a braking member connected to two linear actuators controlled by position and provided with position sensors. A position control loop receives a position signal from the sensor and compares it with a reference variable in a subtracter for obtaining a position error. A position compensator receives the position error and outputs a reference current entering a current control loop connected to generate a voltage that supplies the actuator. The compensator incorporates a control transfer function that is variable as a function of an elastic constant of a mass-spring equivalent system, where the mass is the mass of the parts in motion between the braking member and the actuators, and the elastic constant matches with the elastic constant of the elastic elements.

Abstract: The tension is modulated by a weft-braking device controlled by a tension control block programmed for comparing the measured tension with a reference tension, and for transmitting a braking level signal to the weft-braking device, which braking level signal is adapted to minimize the difference between the measured tension and the reference tension. The yarn consumption speed is calculated, then the yarn consumption speed is compared with a predetermined threshold speed, and if the calculated consumption speed overcomes the predetermined threshold value, the tension control block is enabled, while, if the calculated consumption speed is lower than the threshold value, the tension control block is disabled and the last signal generated by the latter is maintained as braking signal, until the yarn consumption speed overcomes again the threshold value.

Abstract: A method for controlling the motion of a yarn stopper magnet in a measuring feeder for textile machines, preferably for weaving machines of the air-or waterjet-type. The stopper magnet has an armature connected to a yarn stopper element, which armature co-acts with at least one electromagnetic coil in order to achieve the desired motion of the stopper magnet. During an initial part of the motion of the stopper element, the electromagnetic coil is supplied with a voltage with an amplitude considerably exceeding the average level of the voltage during the remaining part of the motion, in order to achieve an optimally fast motion with a low input energy amount and thereby a low heat development, as well as low kinetic energy (speed) of the stopper element at the end of its motion.

Abstract: A self-adjusting braking device for weft feeders, comprising a frustum-shaped braking body that acts on a thread, is suspended elastically in front of the drum of the feeder and is pushed into elastic tangent contact with the drum along an exit circumference of the drum. The braking body has, at a larger-diameter region thereof designed to make contact with the drum, a discontinuous annular contact element, with a plurality of through slits which are arranged so as to be equidistant and delimit a row of contact laminas.

Abstract: A method and apparatus for feeding a thread to a textile machine in a twist-free manner, which thread has a band-like character. The thread is taken twist-free from a stock and is stored on a stationary storage drum in a thread feeding apparatus. The thread feeding apparatus has a rotatable central shaft and a winding element which protrudes therefrom. During operation of the thread feeding apparatus, functional twists are produced in the thread only during the transition from the central shaft into the winding element. The twists are inhibited from being transported oppositely to the thread path direction and are regularly conveyed to the storage drum in almost perfect match with the rotations of the central shaft. At least one guide gap that is stationary in relation to the central shaft is provided along the thread path in the area of transition of the central shaft into the winding element.

Abstract: A yarn feeder including a stationary storage body and a yarn brake having a brake element which axially contacts the storage body. The brake element is embodied by a truncated cone-shaped, thin-walled braking band which is held externally in an elastic, circular retaining membrane joined to a carrier ring that is concentric to the brake band. At least outside the retaining area for the brake band, several areas having a reduced wall thickness are provided in the retaining membrane.

Abstract: The invention relates to a thread that is fed to a textile machine in a twist-free manner and has a band-like character. The thread is taken from a stock in a twist-free manner and is mounted on a stationary storage drum in a thread feeding appliance having a rotatable central shaft and a winding element which protrudes therefrom and towards the outside. Said thread is supplied to the textile machine in an overhead manner and by means of the storage drum. During operation of the thread feeding appliance, functional twists are produced in the thread only during transition from the central shaft into the winding element. Said twists are inhibited from being transported back against the thread path direction and, together with the thread, are regularly conveyed to the storage drum in almost perfect match with the rotations of the central shaft.

Abstract: A ring-shaped, thin walled braking body with a circumferentially continuous and conical braking surface in a yarn brake for a yarn feeding device. The braking body is held by a first spring assembly in its outer region in a ring-shaped carrying structure. The braking body is formed as a closed circular ring with the conical braking surface positioned adjacent to the inner diameter. The braking surface is continued by a plurality of outwardly extending lamellas having an arc curvature. The lamellas define the first spring assembly. The outer ends of the spring lamellas are interconnected by a ring element which can be mounted to the carrying structure. In a yarn feeding device equipped with the yarn brake, the carrying structure is supported in an universal joint such that it can tilt relative to the support to all sides.

Abstract: An anti-balloon device, to be placed downstream of a weft feeder for weaving looms, comprising a structure which forms a substantially tubular through cavity, preferably substantially frustum-shaped; the cavity is crossed by an unwinding thread that arrives from the weft feeder and controls the passage of the thread, by opposing the centrifugal force that affects it. The structure is shaped like a bottomless basket which is formed by rods lying longitudinally between end elements which connect the rods; the end elements are end rings which are mutually angularly spaced so as to surround the cavity in order to control the passage of the thread.

Abstract: A yarn feeding device including a storage drum for a yarn supply and a sensor device located outside the storage drum in a sensor housing. The sensor device includes several movably mounted sensor arms, each of which extends from an axis with a sensor arm carrying a sensor base to the yarn supply on the storage drum where it can be moved out of a home position. The yarn feeding device further includes a spring system which impinges on the sensor arm, as well as a signal-generating device for detecting the position of the sensor arm. The sensor arms and their sensor arm parts are mounted on a common axis.

Abstract: A yarn feeding device having a storage body defining a frontal withdrawal rim which forms a yarn braking zone of a yarn brake in co-operation with a circumferentially continuous braking band in the shape of a frustocone jacket and made of a material which is elastically deformable perpendicular to the generatrix of the frustocone. The yarn brake includes a stationary support for the braking band carrier which presses the braking band substantially axially and resiliently against the withdrawal rim. The braking band is held in a floating manner in relation to the withdrawal rim and in relation to the braking band carrier.

Abstract: In a yarn braking device (B) of a yarn feeder (F) for looms—of the type comprising an annular brake element (E) having a substantially conical and circumferentially continuous braking portion (P), of which at least the radial flexibility is significant and which is positioned coaxial to a body shaped as a drum (4), around which is wound a weft yarn reserve, under an axial spring load (K) and in peripheral contact, along an essentially circular braking zone (Z), with a rim (W) of said drum (4) from which the yarn (Y) is withdrawn, and a flexible and wearproof friction surface structure (S) provided on said braking portion (P) in said braking zone (Z)—said friction surface structure (S) is formed by a plurality of separate elements (C) contacting said braking portion (P) in said braking zone (Z) and movable one in respect of the other.

Abstract: An axial disc brake, particularly for a yarn feeding device, having braking surfaces which are axially pressed against each other with a predetermined yieldable contact pressure. One of said braking surfaces has a spherical convex shape, and the other braking surface is conical with a cone axis lying at least approximately along the axis of the disc brake. The axial disc brake can be provided at the front end of a storage drum of a yarn feeding device of a projectile or gripper weaving machine, such that the yarn withdrawn from the storage drum rotates like the pointer of a clock along a yarn guiding surface and directly enters into the contact zone of the braking surfaces without deflection, and is deflected after having passed the contact zone gently in the axial direction.

Abstract: A yarn feeder having a stationary storage drum defining at least one cylindrical and circumferentially closed circumferential section, and a stationarily held ring-shaped yarn control element surrounding the circumferential section. The yarn control element is a finite band having a generally planar cross-section and is positioned on the circumferential section with mutually aligned, neighboring ends. The band is resistant against extension in the circumferential direction and is yieldable in the radial direction of the storage drum. Further, the band is preloaded against the circumferential section by means of an elastic tensioning device.

Abstract: A measuring feeding device for an air or water jet weaving machine having a stationary storage body for a yarn store consisting of yarn windings wound on tangentially in a predetermined winding direction, from which yarn store the yarn can be withdrawn overhead of the storage body. The device includes a stop element associated with the storage body which can be moved by means of a control unit between a stop position blocking withdrawal of the yarn and a release position allowing withdrawal of the yarn, and a yarn clamping device having a displacement drive and a brake shoe which is adjustable between a lifted position and a yarn clamping position. The braking shoe, in the yarn clamping position is positioned behind the stop element in the winding direction and is maintained in the yarn clamping position after a stroke of the stop element into the release position.

Abstract: A brake for loom weft yarn feeding device is arranged between a front portion of the drum, on which the yarn coming from a conventional bobbin is wound, and a space defined by a hollow enclosing and covering element. The covering element has a front orifice and is positioned in front of the drum. The element has a substantially cone-shaped or spherical cap configuration, wherein a brake is provided comprising a body of round, oval or possibly even quadrangular plan, consisting of one or more intermediate segmental rings, within approximately semicircular profile, which are fitted with at least one head in a portion of lesser diameter than those of the segmental rings at either end. The weft yarn is comprised and compressed between the rim of one of the heads and the inner wall of the hall element, immediately before exiting therefrom through the orifice.