Tsudakoma Corp.

Tsudakoma Kogyo Kabushiki Kaisha

Yoshitaka Fujita

Tsutomu Sainen

Toshiyuki Sakano

Kensuke Wakamatsu

Toshiki Imai

Kosuke Maenaka

Toshio Nakagawa

Yoshitsugu Tamura

A weft yarn feed device (1) comprises a measuring and storing drum (7) for storing a predetermined length of a weft yarn (4) thereon for picking operation, a rotary yarn guide (6) for winding the weft yarn (4) on the measuring and storing drum (7), a feed motor (8) for rotating the rotary yarn guide (6), a drive control unit (3) for controlling the operation of the feed motor (8), and a command control unit (2) which gives commands to the drive control unit (3). The length of the weft yarn (4) wound on the measuring and storing drum (7) is detected accurately on the basis of the relation between the number of rotation of the rotary yarn guide (6) and that of the crankshaft of the loom, and a detection signal indicating the length of the weft yarn (4) wound on the measuring and storing drum (7) is fed back to the command control unit (2) to control the feed motor ( 8) properly for winding a predetermined length of the weft yarn (4) on the measuring and storing drum. The drive control unit (3) comprises a reference setting device (23) which provides a voltage corresponding to a reference rotating speed of the feed motor (8) so that the feed motor (8) is driven continuously for rotation at a slightly varying rotating speed about the reference rotating speed, and preparatory winding controller (26) for controlling the feed motor (8) for winding the predetermined length of the weft yarn (4) on the measuring and storing drum (7) while the loom is stopped.

Weft yarn feeding device for a loom

An apparatus for controlling a let-off motion in a loom having a let-off motion motor includes a tension detector for detecting a warp tension to produce a tension correction signal, a control unit responsive to the tension correction signal for producing a speed signal, a driving amplifier for controlling the let-off motion motor in response to the speed signal, a warp coil diameter detector for issuing a warp coil diameter correction signal inversely proportional to the diameter of a warp coil on a beam to the driving amplifier, and a normal-reverse rotation control unit responsive to the warp coil diameter correction signal for selectively applying prescribed normal- and reverse-rotation signals dependent on a rotation command to the driving amplifier. With this arrangement, the motor is rotated at a desired constant speed for feeding out or rewinding the warp yarn for a desired length irrespectively of the warp coil diameter. In an inching mode of operation, the motor is rotated in a normal or reverse direction for an interval equivalent to one pick each time a main shaft of the loom turns past a certain rotational angle, so that the warp yarn is kept under a desired tension.

Apparatus for controlling motor-driven let-off motion for looms

A method of controlling a motor-driven let-off motion in a loom including a system for controlling a let-off motion motor includes the steps of sampling a variation of warp tension during each revolution of a main shaft of the loom, effecting at least proportional and integral control modes on the average of sampled values, adding a proportional and integral output to a basic speed signal at a prescribed ratio, and applying a sum signal to the system for controlling the let-off motion motor. An apparatus for controlling a motor-driven let-off motion in a loom including a system for controlling a let-off motion motor includes an average computing unit for computing the average of warp tension variations detected at a plurality of sampling times while a main shaft of the loom revolves, a control unit for effecting at least a proportional and integral computation on the average to produce a proportional and integral output, a basic speed computing unit responsive to information indicative of the number of RPM of the main shaft of the loom, the diameter of warp coils on beams, and the number of beatings for computing a basic speed, and a speed command computing unit responsive to the proportional and integral output and the basic speed for adding the proportional and integral output to the basic speed at a prescribed ratio to generate a speed command signal and for applying the speed command signal to the system for controlling the let-off motion motor. With this arrangement, there is no time-delay element in the control system and hence any tension variations can be detected quickly. When the loom is stopped in operation, the integral of a warp tension prior to the stoppage of the loom is stored. When the loom is restarted, the stored integral is issued to suppress any unwanted tension variations of the warp yarns. Since a tension compensation gain is not relatively varied when the diameter of a warp coil is changed, the control system can provide ideal control characteristics.

Method and apparatus for controlling motor-driven let-off motion for

For ideal stoppage of loom rotation at a constant crank angle, initiation of braking action on loom rotation is always automatically and properly timed on the basis of initial stop lag angle representative of the current braking function so that the resultant actual stop angle should match the preselected stop crank angle and, more preferably, the initial stop lag angle is renewed to cover gradual deterioration in the braking function.

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Kanazawa, Japan

Yoshitaka Fujita