Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Patent
1996-10-30
1998-03-10
Falik, Andy
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
242 4713, D03D 4736, B65H 122
Patent
active
057250278
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is related to a pre-unwinding device for use in a weaving loom, and more in particularly to a spoolless weaving loom using a weft injector.
Weaving looms, in particular those from the latter type, are provided with a pre-unwinding device that unwinds a weftthread from a supply bobbin to produce a texture or weave, and a winding device in particular a hydraulic or pneumatic injector that is positioned in between the supply bobbin and a device, for the introduction of the weftthread in between the warpthreads.
The winding device winds the thread by a relative rotation of the thread with respect to the winding device, in adjacent, whether separated or unseparated, windings. In general the winding device is stationairy and the thread is wound onto it by an rotating arm that is hollow.
The thread is drawn off the winding device by the above-mentioned device, for instance the injector and transferred in between the warpthreads.
After drawing off the required length of the thread, which equals approximately the width of the total system of adjacent warpthreads, the drawing of the thread is stopped and the thread is cut.
To cause the stopping of the thread, in order to determine the length of the weftthread, a stopping device is provided in a receiving cylinder which surrounds the winding device, that is positioned and shaped in such a way that as soon as the thread discharge from the winding device has to stop moving, is activated within the receiving cylinder and the continuation of the transport is impeded.
The stopping device can be a pin, for example that is driven electro-magnetically and moves about perpendicular to the axis of the winding device.
In between the winding device and the surrounding cylinder the thread moves towards the cylinder, and from this point towards the device, for instance the injector, to introduce the weftthread in between the warpthreads.
The surrounding cylinder is usually provided with a dome-shaped extension including a downstream located central discharge opening for the thread.
By suitably dimensioning the winding device and the surrounding receiving cylinder and a correct installation of the stopping device, it is possible to achieve only a slight bending of the discharged thread. This implies a smooth winding of the thread in order to prevent, also for thin and vulnerable threads, needless friction which might result in coil ball-formation, damage to threads and possibly breakage.
Such a correct dimensioning and positioning is almost impossible if the winding device has a variable adjustable diameter and the receiving cylinder does not have a variable diameter.
Such types of devices are known and, e.g., described in EP-A-9 111 274 5.4.
At a smaller diameter setting of the winding body and an unchanged diameter of the receiving cylinder the annular clearance in between these parts is increased, and therefore the thread might undergo a larger "bend".
This problem could be solved by decreasing the diameter of the receiving cylinder. This implies practically the usage of different receiving cylinders with different diameters or a receiving cylinder with variable diameter. Both solutions are either too cumbersome and/or too complex and therefore expensive.
SUMMARY OF THE INVENTION
An object of the invention is to solve these disadvantages and obtain further advantages.
A pre-unwinding device according to the invention for use in a spoolless weaving loom, in particular using a weft injector, comprising a central shaft enclosed by a housing, whereby the thread is taken from a supply coil, and by a relative rotation of the central shaft and a winding body, is wound on that body in adjacent eventually separated strands, whereby the winding body has a adjustable diameter in a plane perpendicular to the central shaft and is situated within a surrounding receiving cylinder for thread leaving the winding body, provided with a stopping device having such a shape and position that at the moment that the thread discharge from the winding body ha
REFERENCES:
patent: 3971522 (1976-07-01), Pfarrwaller
patent: 4632154 (1986-12-01), Maina
patent: 4747549 (1988-05-01), Balzarotti
patent: 5133388 (1992-07-01), Tholander
patent: 5211207 (1993-05-01), Ichikawa
patent: 5520226 (1996-05-01), Pedrini
Falik Andy
TE Strake B.V.
LandOfFree
Weft feeder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Weft feeder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Weft feeder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-131757