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US-20260125830-A1 - WEFT FEEDER FOR WEAVING LOOMS WITH SPACED THREAD COILS AND ADJUSTABLE- DIAMETER DRUM

US20260125830A1US 20260125830 A1US20260125830 A1US 20260125830A1US-20260125830-A1

Abstract

A weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum formed of several fixed sectors, each provided with respective support shanks housed in respective seats formed in a static support disk, coaxial to a drive shaft of the weft feeder, and wherein the spacing of said spaced coils on the drum is caused by the oscillatory and tilting movement of several moving sectors, each provided with respective support shanks housed in respective seats formed in a tilting support disk, eccentric and skew with respect to said drive shaft of the weft feeder, and wherein elastic elements are provided, which exert a compressive force on said shanks to keep said fixed sectors and said moving sectors in a position of stable engagement within their respective seats. The fixed sectors and the moving sectors are each provided with a single support shank in the general shape of a trapezoidal right prism, housed in a respective seat consisting of a cavity having a congruent trapezoidal shape, and said elastic elements exert a compressive force on the major base of said support shank having the shape of a trapezoidal right prism.

Inventors

  • Riccardo Comotto

Assignees

  • Roj S.R.L.

Dates

Publication Date
20260507
Application Date
20251104
Priority Date
20241107

Claims (11)

  1. 1 ) A weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum (D), wherein said drum (D) is formed of several fixed sectors ( 5 ), each provided with respective support shanks ( 5 g ) housed in respective seats formed in a static support disk ( 6 ), coaxial to a drive shaft (A) of the weft feeder, and wherein the spacing of said spaced coils on the drum (D) is caused by the oscillatory and tilting movement of several moving sectors ( 7 ), each provided with respective support shanks ( 7 g ) housed in respective seats formed in a tilting support disk ( 8 ), eccentric and skew with respect to said drive shaft (A) of the weft feeder, and wherein elastic elements which exert a compressive force on said shanks ( 5 g , 7 g ) are provided, to keep said fixed sectors ( 5 ) and said moving sectors ( 7 ) in a position of stable engagement within their respective seats, wherein the fixed sectors ( 5 ) and the moving sectors ( 7 ) are each provided with a single support shank ( 5 g , 7 g ) having the general shape of a trapezoidal right prism, housed in a respective seat consisting of a cavity having a congruent trapezoidal shape, at least to the limited extent of its converging side walls, and wherein said elastic elements exert a compressive force on the major base of said support shank having the general shape of a trapezoidal right prism.
  2. 2 ) The weft feeder for weaving looms according to claim 1 , wherein said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ) are in the shape of an isosceles trapezoidal right prism.
  3. 3 ) The weft feeder for weaving looms according to claim 1 , wherein the minor bases of said support shanks ( 5 g , 7 g ) in the shape of a trapezoidal right prism include elements for guiding their longitudinal movement and regulating their position within their respective seats.
  4. 4 ) The weft feeder for weaving looms according claim 1 , wherein said compressive force is: a. greater than the minimum clamping force required to keep the adjustment position of the support shanks ( 5 g , 7 g ) unchanged, in normal operation of the weft feeder, and b. less than the maximum clamping force still allowing said support shanks ( 5 g , 7 g ) to slide within their respective seats, in an operation to adjust the position of said fixed sectors ( 5 ) and moving sectors ( 7 ).
  5. 5 ) The weft feeder for weaving looms according to claim 1 , further including quick-tensioning fasteners, bistable between a locked position and an unlocked position, which modify the compressive force exerted by said elastic elements on the support shanks ( 5 g , 7 g ).
  6. 6 ) The weft feeder for weaving looms according to claim 5 , wherein said modified compressive force: a. in the locked position is greater than the minimum clamping force required to keep the adjustment position of said support shanks ( 5 g , 7 g ) unchanged, under every operating condition of the weft feeder, and b. in the unlocked position is less than the maximum clamping force still allowing said support shanks ( 5 g , 7 g ) to slide within their respective seats, in an operation to adjust the position of the fixed and moving sectors ( 5 , 7 ).
  7. 7 ) The weft feeder for weaving looms according to claim 1 , wherein said elastic elements include wave springs or cup springs ( 10 , 13 ) acting on said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ) under a certain preload imposed by a closing ring ( 11 , 14 ).
  8. 8 ) The weft feeder for weaving looms according to claim 7 , further including a flat and rigid shank-pressing ring ( 9 , 12 ), interposed between said elastic elements ( 10 , 13 ) and said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ).
  9. 9 ) The weft feeder for weaving looms according to claim 5 , wherein said quick-tensioning fasteners include a locking ring ( 23 ) interposed between said elastic elements ( 10 , 13 ) and said closing ring ( 11 , 14 ), and free to rotate therebetween, the opposing contact surfaces of the locking ring ( 23 ) and the closing ring ( 11 , 14 ) being wavy contact surfaces ( 24 ) which cooperate for changing the axial position of the locking ring ( 23 ) during its rotation, between a position further away and a position closer to the closing ring ( 11 , 14 ) and thereby varying the preload on the elastic elements ( 10 , 13 ).
  10. 10 ) The weft feeder for weaving looms according to claim 9 , wherein said locking ring ( 23 ) is provided with bulges ( 25 ) which determine limit positions of its rotation against corresponding end stops ( 28 ) formed in said closing ring ( 11 , 14 ).
  11. 11 ) The weft feeder for weaving looms according to claim 10 , wherein said bulges ( 25 ) are provided with grip holes ( 26 ) for the engagement of control levers.

Description

FIELD OF THE INVENTION The present invention relates to a new weft feeder for weaving looms with spaced thread coils, and in particular for air-jet and water-jet looms, which, in addition to the normal functions already offered by the currently available weft feeders of the known type, also allows a particularly quick adjustment of the drum diameter. PRIOR STATE OF THE ART As it is well known, weft feeders are weft thread feeding devices, interposed between the loom and the spools, which feeds the weft thread to the loom, by continuously accumulating it in successive spaced 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 in the axial direction from the weft feeder drum at a variable speed—during the insertion of the weft thread in the shed—without thus causing tension peaks in the weft thread, which would undermine both the thread itself integrity and the fabric quality. Weft feeders are devices which have been in common use for many years now in the weaving mills and, over the years, they have been enhanced with additional control functions, in addition to the basic functions mentioned above, which allow to check the weft thread constant presence at the weft feeder critical points, to adjust the amount of weft thread accumulated in the reserve and the mutual distance, or pitch, between the individual coils, to brake the outgoing weft thread in order to contain the dynamic effects caused by the sudden drawing-out acceleration, to measure the length of the weft thread section drawn-out by the insertion devices and, finally, to stop the weft thread drawn-out as soon as a predetermined length has been supplied. The amount of weft thread accumulated in the reserve obviously depends on the weft feeder drum diameter on which such reserve is wound, and on the number of coils that can be simultaneously accommodated on said drum. To increase the adjustment range of a single weft feeder and make thus a single weft feeder suitable for use both on air-jet and water-jet looms even of very different heights, in addition to the possibility of varying the number of coils by modifying the pitch between successive coils, the possibility of modifying the drum diameter has also been introduced. Given, in fact, that the inserted weft length corresponds to an integer number of coils, a variation of the drum diameter allows for fine adjustment of such length as there is a single stopping point for the weft thread exiting the weft feeder drum. To this end, the drum is normally formed of several fixed sectors—usually four—each independently fixed to the weft feeder body. In the case of adjustable-diameter drums, the fixed sectors are fixed to the weft feeder body in an adjustable radial position and then clamped in the desired position by means of locking screws. To automate and speed up this adjustment process, WO2015/169612 discloses a weft feeder provided with a non-reversible gear system, operated by a servo control. This system allows the radial position of three adjustable sectors of the weft feeder to be simultaneously adjusted, while also ensuring that they are locked in the desired adjustment position without the use of locking screws, thanks to the non-reversibility of the gear system. Each adjustable sector is provided with two support shanks, either parallel or slightly converging, and the gear system cooperates with only one of said shanks, which due to this reason is provided with a rack portion, while the other shank slides inside a respective guide to improve the stability of the adjustable sector. The fourth sector has an invariable position, as the presence of the weft thread is optically detected thereon and therefore, for greater simplicity of construction, it was decided to always keep such sector at a fixed distance from the weft feeder arm, parallel to the same, on which arm the optical sensors detecting the weft thread are installed. In the type of weft feeders provided with a device for spacing at a predetermined pitch the individual coils wound on the drum—commonly referred to as weft feeders with spaced coils—it is further provided a corresponding number of moving sectors mounted on a stationary tilting flange which is in turn supported, through the interposition of a ball bearing, by the external surface of a bushing keyed to an eccentric portion of the weft feeder shaft; said bushing is furthermore provided with an external cylindrical surface inclined by a few degrees with respect to the drum surface. Thanks to this arrangement, during the weft feeder shaft rotation, the inclined bushing rotates integrally with said shaft and with the bearing internal ring, causing a combined periodic oscillation of the bearing itself and therefore of the tilting flange which is integral with the bearing external ring. The oscillation of said tilting fl