Roj Electrotex S.p.a.

Fiorenzo Ghiardo

Bruno Maina

An electromagnetic unit coacts with the winding drum of a weft feeding device to control unwinding of weft yarn from the drum. The electromagnetic unit comprises a movable stem surrounded by a pair of adjacent coaxial electromagnetic coils. Energization of one coil causes the stem to move into a position where it blocks unwinding of the yarn, whereas energization of the other coil retracts the stem and permits free unwinding of the yarn.

Electromagnetic blocking unit for a weft storage drum

A device for detecting weft yarn breakage is adapted to be positioned upstream of a weft yarn feeding and storage device, and comprises a signal generator which directs the stoppage of the loom after a predetermined delay time T has elapsed from the moment at which weft yarn breakage is detected. The device comprises an electronic circuit including components which receive signals representative of the speed of the motor shaft and detection of weft yarn breakage. In one embodiment, the motor speed signal is fed to a counter-divider upon detection of weft yarn breakage, which in turn generates a signal after a time inversely proportional to the motor speed. This signal can be fed to a monostable circuit which generates the pulse for stopping the loom, the delay time T being in relation to the detected speed of the motor of the weft yarn feeding and storage device.

Weft-feeder with automatic adjustment of the delay time, for weft

A method and apparatus to adjust the motor speed in yarn feeders for textile machines and, in particular, weft feeders for weaving looms, wherein a yarn reserve is wound on a rotary drum held stationary, by a winding arm rotated by the motor. Photoelectric cells positioned close to a yarn outlet end of the drum emit signals which adjust--in cooperation with detection of the rotations of the winding arm--the motor speed of the feeder. These signals differ from each other according to whether an advancing turn of the yarn reserve intercepts a luminous beam for a relatively long period of time or whether yarn drawn from the reserve by the loom intercepts a luminous beam for a relatively short period of time. These signals are discriminated so as to adjust said speed, so as to guarantee the constant presence of an adequate yarn reserve on the drum.

Adjustment of motor speed in yarn feeders according to yarn reserve

A weft feeding device for weaving looms regulates the motor speed, according to the amount of yarn wound on the drum at least two photoelectric cells (11, 12) are provided one of which (11) checks the amount of yarn (3) wound on the drum (1), while the other (12) measures the transparency of the protection glass (15) provided on the cells. These photoelectric cells (11, 12) cooperate with an electronic circuit, which processes their signals (31, 32) in order to automatically compensate the transparency variations in the protection glass (15), thereby allowing a more uniform regulation of the motor speed of the weft feeding device.

Weft feeding device for weaving looms

Weft feeder for weaving looms, of the type wherein the drum (1) around which the weft yarn winds to form the reserve is held stationary, while the turns (3) of the reserve are laid thereon by a rotating reel (2) and are moved forward, mutually spaced, by a set of columns (5) prevented from rotating in respect of said drum (1), but partially and variably emerging from special seats of its periphery. The ensemble of columns has a frustoconical profile, each column (5) being tapered towards the feeder outlet end, until it no longer emerges from the seats where there is maximum tapering. A photoelectric cell unit (8), moving parallel to the axis of the drum (1), detects the presence and the consistency of the weft yarn reserve wound thereon, in order to control the rotation and regulate the speed of the motor of the feeder.

Weft feeder for weaving looms

An electric device for the control of yarn feeding devices for weaving machines, of the type providing for the presence of a yarn supply wound onto a drum and comprising an electric three-phase driving motor, wherein, in order to change the speed of the motor, this latter is supplied with AC voltage, phase controlled by triacs. For this purpose, three signals are used representing a selected speed for the motor, the true speed of the motor itself and, respectively, the presence of the yarn supply on the drum, these signals being compared and processed into an electronic circuit, in order to produce signals forthe control of the triacs. The three signals are compared in a circuit generating a signal which must in turn be compared with three periodic ramp signals having the same phase and a period half those of the three supply voltages of the motor, in order to generate square wave signals for energizing the corresponding triacs.

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Vigliano Biellese, Italy

Fiorenzo Ghiardo