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US-20260125831-A1 - Weft feeder with adjustable-diameter drum for weaving looms, comprising an electromagnet unit controlling the weft thread release equipped with a quick-release device to adjust and fix its working position

US20260125831A1US 20260125831 A1US20260125831 A1US 20260125831A1US-20260125831-A1

Abstract

Weft feeder for weaving looms with thread coil separation comprising a winding group (W) to wind a weft thread onto a weft feeder drum (D), and an electromagnet unit (E) to control the movement of a stop pin (P) which prevents the weft thread from being released from said drum (D), wherein said electromagnet unit (E) is movable in a radial direction with respect to an axis of the weft feeder drum (D), along a pair of guide means ( 1 , 2 ) provided in the base body (C) of said weft feeder and in said electromagnet unit (E), respectively, which consist of a pair of fixed guides ( 1 ) and a pair of mobile guides ( 2 ) symmetrically arranged with respect to an axial plane of the weft feeder passing therebetween and parallel thereto, each pair of guides having flat contact surfaces ( 1 a , 2 a ) symmetrically inclined with respect to said axial plane of the weft feeder. A single locking/unlocking means ( 3 , 4 ) having an axis parallel to the drum (D) axis stably fixes said electromagnet unit (E) in a predefined position and includes a pawl ( 3 ) housed in an undercut recess, provided between said pair of fixed guides ( 1 ) or in the weft feeder base body (C), and a tie-rod ( 4 ) connected to said pawl ( 3 ).

Inventors

  • Claudio Mariuzzo

Assignees

  • Roj S.R.L.

Dates

Publication Date
20260507
Application Date
20241218
Priority Date
20231227

Claims (9)

  1. 1 . Weft feeder for weaving looms with thread coil separation, comprising a winding group (W) to wind a weft thread on a drum (D) of the weft feeder, and an electromagnet unit (E) to control the movement of a stop pin (P) which prevents the weft thread from being released from said drum (D), wherein said electromagnet unit (E) is movable in a radial direction with respect to an axis of the weft feeder drum (D), along guide means ( 1 , 2 ) provided in the base body (C) of said weft feeder and in said electromagnet unit (E), respectively, and wherein said guide means ( 1 , 2 ) comprises a pair of fixed guides ( 1 ) and a pair of mobile guides ( 2 ), both parallel to said radial direction and mutually coupled, at least one of said fixed guides ( 1 ) and a mobile guide ( 2 ) coupled therewith having flat contact surfaces ( 1 a , 2 a ) inclined with respect to the weft feeder axis, characterized in that a single locking/unlocking means ( 3 , 4 ) is also included, having an axis parallel to the drum (D) axis, for stably fixing said electromagnet unit (E) in a predefined position along said guide means ( 1 , 2 ), so that upon tightening said single locking/unlocking means ( 3 , 4 ) said guide means ( 1 , 2 ) automatically cause centering of the electromagnet unit (E) with respect to the weft feeder axis, and prevent its rotation about the axis of said locking/unlocking means ( 3 , 4 ), wherein said single locking/unlocking means ( 3 , 4 ) includes a pawl ( 3 ) housed in an undercut recess provided between said pair of fixed guides ( 1 ) or in the weft feeder base body (C), and a tierod ( 4 ) connected to said pawl ( 3 ).
  2. 2 . The weft feeder for weaving looms with thread coil separation as in claim 1 , wherein said tierod ( 4 ) is a screw engaged with said pawl ( 3 ).
  3. 3 . The weft feeder for weaving looms with thread coil separation as in claim 1 , wherein said tierod ( 4 ) has a predetermined length and is connected to said pawl ( 3 ) at one end and to a quick-release locking/unlocking device at its opposite end.
  4. 4 . The weft feeder for weaving looms with thread coil separation as in claim 3 , wherein said quick-release locking/unlocking device includes a manually operated eccentric lever ( 6 ) hinged to the body ( 5 ) of said electromagnet unit.
  5. 5 . The weft feeder for weaving looms with thread coil separation as in claim 3 , wherein the predetermined length of said tierod ( 4 ) is adjustable during manufacturing or calibration.
  6. 6 . The weft feeder for weaving looms with thread coil separation as in claim 5 , further comprising an elastic means applying a preload force on said pawl ( 3 ) in the unlocked position of the locking/unlocking device.
  7. 7 . The weft feeder for weaving looms with thread coil separation as in claim 6 , wherein said elastic means comprises a small block ( 7 ), made of rubber or other elastic material, interposed between the eccentric lever ( 6 ) and an abutment surface of the electromagnet unit body ( 5 ).
  8. 8 . The weft feeder for weaving looms with thread coil separation as in claim 6 , wherein said preload force is high enough to prevent the electromagnet unit from moving under the sole action of its own weight, and wherein said preload force is low enough to allow the electromagnet unit movement along the pair of fixed guides ( 1 ) when a suitable force is applied thereon in such a direction.
  9. 9 . The weft feeder for weaving looms with thread coil separation as in claim 1 , wherein at least one between said pair of fixed guides ( 1 ) and said pair of mobile guides ( 2 ) is made of a self-lubricating material.

Description

FIELD OF THE INVENTION The present invention relates to a new weft feeder for weaving looms, and particularly for air jets looms and water jet looms, which includes, in addition to the normal functions already offered by the currently available weft feeders of the known type, an electromagnet unit controlling the weft thread release, equipped with a quick-release adjustment device to obtain a precise adjustment of its working position. PRIOR STATE OF THE ART As is well known, weft feeders are weft thread feeding devices, interposed between the loom and the yarn spools, which feeds the loom with the weft thread by continuously accumulating it in successive coils on a cylindrical drum at as constant a speed as possible—in the clockwise or counterclockwise direction depending on the thread features—so as to create a reserve of weft thread which is subsequently extracted from the weft feeder drum in the axial direction, at variable speed, during the operation of insertion in the shed, without thus causing tension peaks in the weft thread, which would undermine both the integrity of the thread itself and the quality of the fabric. Weft feeders are devices which have been in current use for many years in the weaving mills. Along their evolution over the years, in addition to the basic functions mentioned above, they have been enhanced with additional control functions which allow to check the weft thread constant presence at certain critical points of the weft feeder, to adjust the amount of weft thread accumulated in the reserve and the distance between the individual coils, to slow down the outgoing weft thread in order to contain the dynamic effects caused by the sudden drawing acceleration, and finally to control the weft thread release in a predetermined length for insertion in the shed formed by the warp threads. To be able to correctly carry out the above functions, the weft feeder (FIG. 1) is equipped with an optical unit and an electromagnet unit E (hereinafter also referred to as “ELM unit”). The optical unit includes one or more optical sensors and performs the function of monitoring the weft thread winding on the drum D by a winding group W which is integral with the weft feeder hollow shaft A, by retroactively controlling the weft feeder electric engine which controls the hollow shaft A rotation and therefore the deposition of new coils of weft thread on the drum D, as well as the function of counting the number of coils released from drum D to the weft insertion devices. The ELM unit controls the rectilinear movement of a weft thread stop pin P between an advanced position, wherein its free end is inserted into a corresponding seat provided in the drum D, thus preventing the weft thread from being released from the weft feeder drum, and a retracted position which allows instead the weft thread to be released. Thanks to the combined action of the optical unit and the ELM unit the weft thread may thus be drawn from the loom in a predefined number of coils, corresponding to the desired length of weft thread to be inserted in the shed. For a correct operation of the optical unit and the ELM unit, the distance between the ELM unit and the drum D shall be determined with such a precision as to allow the optical unit sensors to correctly detect the passage of the weft thread, and the stop pin P of the ELM unit to sufficiently enter the corresponding seat of the drum D to hold the weft thread coils on the drum D. In weft feeders with adjustable-diameter drum, to which the present invention is addressed, the drum D working diameter may be modified in every single processing, in order to change the length of the weft thread section fed to the loom, and it is then necessary that the position of the whole ELM unit, mounted directly on the weft feeder base body C, is adjusted as quickly and stably as possible, to chase the new position of the drum D and then stably maintain a predetermined optimal working distance from the same. Currently, the ELM unit slides along a pair of guide means, respectively provided in the weft feeder base body C and in the ELM unit itself, and having a radial direction with respect to the weft feeder drum D. The ELM unit is then fixed in a desired position by a pawl which slides within the guide means provided in the base body. Said pawl is in fact secured to the ELM unit via the engagement with a screw passing through the same, in the parallel direction to the drum D axis, and may be therefore locked in position by acting on said screw to pull the pawl into abutment against said guide means. In this way, the ELM unit sliding may be stopped at any desired position along said guide means. However, the ELM unit support and locking device described above shows two main drawbacks: the screw/pawl assembly has inherent plays which do not allow a precisely repeatable adjustment of the ELM unit position. In particular, the ELM unit remains partially free to swing about the screw/pawl assembly