A control method and system for weft-braking devices for automatically adjusting the mechanical tension of the yarn in weaving maschines

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(11)

EP 1 314 806 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	12.11.2003 Bulletin 2003/46

(43)	Date of publication A2:
	28.05.2003 Bulletin 2003/22

(21)	Application number: 02013025.8

(22)	Date of filing: 13.06.2002

(51)	International Patent Classification (IPC)⁷: D03D 47/34

(84)	Designated Contracting States:
	AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR
	Designated Extension States:
	AL LT LV MK RO SI

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Priority:

25.07.2001 IT TO20010737

(71)	Applicant: L.G.L. Electronics S.p.A.
	24024 Gandino (Bergamo) (IT)

(72)	Inventors:
	Zenoni, Pietro 24026 Leffe (BG) (IT) Gotti, Luca 24021 Albino (BG) (IT)

(74)	Representative: Spandonari, Carlo, Dr. Ing.
	Spandonari & Modiano s.r.l. corso Duca degli Abruzzi 16 10129 Torino 10129 Torino (IT)

(54)	A control method and system for weft-braking devices for automatically adjusting the mechanical tension of the yarn in weaving maschines

(57) An improved method for controlling electrically operated weft-braking devices, capable of automatically adjusting the mechanical tension of the weft yarn (F) in mechanical-picking weaving machines (TE), is disclosed herein. The excitation current (Ie) of the weft-braking device (LF) is controlled by an adjustment loop (A) using a signal (tens-mis), which is a measure of the actual tension of the yarn, as a feedback signal for the adjustment loop (A). The improvement comprises employing an average value (TMx), which is computed at predetermined intervals (x) of weft picking and for a predetermined number (i) of picking strokes, in order to measure the direct tension of the thread (F), so that said average value (TMx) is substantially stable and not affected by fluctuations due to variations of the parameters of the weaving process.

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