WO2002052081A2

WO2002052081A2 - An improved weft supplier, particularly for fluid-jet looms

Info

Publication number: WO2002052081A2
Application number: PCT/IB2001/002283
Authority: WO
Inventors: Pietro Zenoni; Giovanni Pedrini
Original assignee: L.G.L. Electronics S.P.A.
Priority date: 2000-12-22
Filing date: 2001-12-03
Publication date: 2002-07-04
Also published as: ITTO20000222U1; ITTO20000222V0; WO2002052081A3; IT249345Y1

Abstract

The weft supplier comprises a stationary drum (TA) covered with anonreflective coating for purposes of surface hardening, a swivelarm (BR), for winding a plurality of loops of yarn (F) on the drum (TA) for building a weft stock (RT). In order to count the loops released at each weft insertion, a light source (SL) generates a light beam (r) that is received by a photocell (CF) after reflection on a mirror-polished metal plate (ER) set in the external surface of said drum (TA).

Description

"An improved weft supplier, particularly for fluid-jet looms"

The present invention is concerned with an improved weft supplier particularly for fluid-jet looms.

The use of weft supplying devices that, in the case of fluid-jet looms, may also act as weft pre-metering devices, is known and usual in the field of weaving.

Such devices, when inserted between the reel and the loom, fulfill the task of supplying the yarn, or possibly a predetermined length of yarn, at each weft insertion, by releasing it from a weft stock stored in the device.

Typically, a system for supplying weft to looms comprises supplier devices, each comprising a stationary drum having a continuous or a multi-sector skirt, and provided with a swivel arm to wind up loops of yarn to build said weft reserve, counting means for counting the loops that are released at each weft insertion, counting means for counting the loops that are re-wound on the stationary drum in order to restore the weft reserve, and a controlling micro-controller that, according to the number of loops that have been unwound, controls the motor of the swivel arm which re-winds up the loops in order to restore the weft reserve. Where the weft supplier also acts as a meter for the inserted weft, a weft-stopper finger is associated with the drum, and is driven by electromagnetic means to release the yarn and unwind from the drum and to stop said unwinding when the pre-metered length has been reached.

Typically, in order to maintain the weft reserve constant, the micro-controller processes pulse signals produced by a pair of sensors, of which the former is optical and detects the flow of the loops as they unwind from the drum, whilst the latter is magnetic and provides signals depending on the rotation of the swivel arm, generated by detecting the passage of a magnet which is attached to the swivel arm.

The first optical sensor includes a photoelectric cell receiving a light beam generated by a source placed adjacent to the drum and reflected by the drum skirt or by the drum sectors. The passage of an unwinding loop temporarily interrupts said beam and dims the photoelectric cell, thereby causing the photocell to generate a corresponding signal signaling the passage of the loop. As a general rule, the skirt or the sectors of the drum of the supplying device is coated, by way of surface hardening, with a thin chrome layer, of a thickness typically in the range of ten to twenty microns. Such chrome layer, when suitably polished at least in the incidence area of said light beam, can also serve as an excellent reflective surface for the beam.

However, in certain applications, e.g. jute or polypropylene weaving, it is common to use drums or drum sectors treated treated so that their surface has a considerably higher hardness. Typically, this is achieved by depositing a superficial plasma layer. However, the plasma layer imparts the treated surface a roughness which it is unfeasible to remove, and the treated surface consequently no longer has the capability to reflect the light beam impinging on the photoelectric cell of the first sensor.

The main object of this invention is to provide an improved weft supplier where the above stated drawback is removed, i.e. where the reflection of the light beam is achieved independently of the characteristics of the superficial layer of the drum.

This object is achieved by inserting, on the surface of said drum skirt or sectors which are subjected to the plasma treatment, a reflective movable member which preferably consists of a mirror-polished metal plate. Advantageously, such a plate is set in a corresponding seat provided on said drum skirt or drum sectors, the seat being depressed so that the plate is level with the outside surface of said drum skirt or sectors. Moreover, said plate is provided with a centering tang and is bonded to its seat by an interposed layer of an adhesive.

Other features and advantages will become apparent from the following detailed description and with reference to the attached drawings, wherein:

Fig. 1 is a partial side view of the fore end of a weft supplier/pre-meter for fluid-jet looms;

Fig. 2 is a detail, to an enlarged scale, of Fig. 1;

Fig. 3 is a perspective view of a drum sector of the supplier of Fig.l, having a reflective movable member, according with the invention.

Fig. 1 shows a supplier-premeter P comprising a stationary drum TA, consisting of a plurality of side-by-side sectors ST, on which a swivel arm BR, operated by an electric motor (not shown), winds a plurality of loops of yarn F to build a weft stock RT. A weft-stopper finger DI (Fig. 2) for stopping yarn F is connected to drum TA and is driven by an electromagnetic actuator AE to release yarn F so that it will unwind from the drum, and to stop said unwinding when a predetermined length has been reached. A light source S, projecting a light beam r towards adjacent sector ST of drum TA, and a photoelectric cell CF, receiving the light beam after reflection on said adjacent sector, are arranged by actuator AE and adjacent drum TA: source SL and cell CF provide an optical sensor for detecting the loops unwinding from drum TA.

In order to achieve reflection of light beam r generated by light source S, and considering that sectors ST of drum TA are coated with a nonreflective surface plasma coating', according to the invention, adjacent sector ST is provided with a reflective movable member ER which preferably consists of a mirror-polished metal plate. Advantageously, such a plate is set in a corresponding seat SR, which is made on said adjacent sector, said seat being depressed so that the plate is level with the external surface of said sector. Moreover, said plate ER is provided with a centering tang CC and is bonded to its seat by means of an interposed layer of adhesive.

A preferred embodiment of the invention has been described, in which, however, numerous changes may be made, such as will be evident for the person skilled in the art, within the scope of the inventive concept.

Claims

1. An improved weft supplier, particularly for fluid-jet looms, comprising a stationary drum (TA), a swivel arm (BR), for winding a plurality of loops of yarn (F) on the drum (TA) for building a weft stock (RT), and optical means (SL-CF) for counting the loops that are released at each weft insertion, wherein said optical means include a light source (SL) generating a light beam (r) received by a photoelectric cell (CF) after reflection on a reflective surface of the drum, characterized in that the reflective surface of said light beam (r) is a reflective movable member (ER) set in the external surface of said drum (TA) or of the sector of said drum (TA); said external surface being covered with a nonreflective coating, typically a plasma coating, for purposes of surface hardening.

2. The weft supplier of claim 1, characterized in that said reflective member (ER) is a mirror-polished metal plate.

3. The weft supplier of claim 1 and 2, characterized in that said metal plate (ER) is set in a corresponding seat (SR), which is obtained on said drum (TA) or drum sector, said seat (SR) being depressed so that the plate is level with the external surface of said drum (TA) or drum sector.

4. The weft supplier of the preceding claims, characterized in that said metal plate (ER) is provided with a centering tang (CC) and is bonded in its said seat by means of an interposed layer of adhesive.