US 4,829,917 AGranted

Control system for hydraulic needle bar positioning apparatus for a tufting machine

AssigneeTuftco Corporation

InventorsMichael R. Morgante, Greogory J. Guzewich, Henry J. Kowal, Christopher La Mendola, Randall E. Stanfield

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Abstract

An electronic computer control for a hydraulic actuator for shifting a needle bar to different transverse positions in a tufting machine. The computer control directs the hydraulic actuator to be driven in response to the predetermined stitch pattern information in the computer control circuit, which determines the amount of relative tansverse shifting of the needle bar for each stitch location, in such a manner that the needle bar is shifted transversely only a needle gauge, or a multiple needle gauge, at a time and only while the needles are out of the backing fabric. The computer control also controls the velocity of the transverse movement of the needle bar in a gradual manner to minimize any shock created by the transverse movement of the needle bar upon the tufting machine. In order to enhance the smooth and gradual shifting movement of the needle bar, the computer control command signals commence prior to the actual commencement of needle bar shifting and terminate prior to the re-entry of the needles into the backing fabric to counteract any delayed inertial movement of the needle bar in response to the computer command signals.

In a tufting machine having a backing fabric support, means for feeding backing fabric longitudinally through the machine, a needle bar supporting a plurality of needles transversely of said machine, yarn supply means for feeding yarns to said needles, and means for reciprocating said needle bar at a predetermined needle stitch rate to drive said needles into and out of the backing fabric upon the backing fabric support, a positioning apparatus for shifting transversely the needle positions relative to the backing fabric, comprising:

(a) a reciprocably movable, hydraulically driven actuator for transversely shifting a needle bar to different needle positions,
(b) pressurized hydraulic fluid supply means for said actuator,
(c) servovalve means for controlling the flow of hydraulic fluid to said actuator,
(d) computer control means including a computer processor and a signal processor, and having input means and output means,
(e) said computer processor comprising programmed digital pattern information corresponding to a stitch pattern pre-determining the relative transverse position of said needle bar for each longitudinal needle stitch position,
(f) stitch encoder means communicating with said input means for producing a plurality of encoder counts for each needle stitch cycle in said computer processor,
(g) means in said computer processor for utilizing said programmed information to produce a plurality of position command signals corresponding to said encoder counts, each position command signal corresponding to a transverse position of said actuator,
(h) means in said computer processor utilizing said programmed information to cause said position command signal to vary linearly with said encoder counts during a predetermined positioning window encoder count interval,
(i) electrical feedback means responsive to the actual position of said actuator producing corresponding feedback signals,
(j) means in said computer processor for comparing each position command signal with a corresponding feedback signal to produce a corresponding drive signal,
(k) means for transmitting each drive signal to said servovalve means to control the flow of hydraulic fluid to said actuator to position said needle bar in a transverse position corresponding to each corresponding drive signal, and
(l) timing means responsive to said encoder counts permitting said actuator to shift transversely only when the needles in said needle bar are above the backing fabric.

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Abstract

Claims13