Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-09-29
2001-11-13
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S131000, C112S273000
Reexamination Certificate
active
06317644
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a textile machine monitor which applies several methods of electronic processing to signals received from a thread feed sensor.
2. Description of Related Art
a. Thread Monitors
The prior art includes a variety of mechanical and electrical devices for monitoring and controlling textile equipment. The present invention adds a number of capabilities that are not addressed in the prior art.
A common thread/yarn monitor employs a mercury switch device which maintains an open circuit condition while the thread/yarn is under tension at the switch location. In the event the thread breaks, a closed circuit results indicating the breakage.
Electronic thread motion sensor devices utilized in the prior art, such as described in U.S. Pat. No.4,429,651, (Tajima), includes a motion
o motion sensor wherein a fault/break is indicated when “no motion” is detected when “motion” is required. The current invention can act prior to thread break, which can prevent: 1) damage to the finished product resulting from snags or mechanical failures which occur prior to a thread break; 2) damage to machines which can occur prior to a thread break, for example, when large amounts of thread wrap on the take-up cam shaft; and 3) waste of time and thread when operators of automatic machines monitor and remove thread spools before exhaustion in order to prevent a break at the end of the spool.
Much of the prior art is limited to tension sensing/analysis, but electronic tension sensing/analysis can address only limited and specific issues. Such prior art includes: U.S. Pat. No. 5,237,944 to Willenbacher, et al.; U.S. Pat. No. 4,628,847 to Rydborn; and, U.S. Pat. No. 4,763,588 to Rydborn. U.S. Pat. No. 5,237,944 to Willenbacher, et al., in fact states that “[m]easurement experiments have shown that such parameters as the speed of sewing, stitch length, and the thread properties cause only insignificant changes in the maximum of the voltage peaks, whereas the setting of the tensioning device substantially affects it.” U.S. Pat. No. 5,237,944 is directed to the analysis of tension changes that are generated by take up type elements of a sewing machine. That invention, however, also requires input feedback from a machine shaft position sensor and detects only a specific input signal pattern for a designated machine type. Changes in machine type or take-up structure would require fundamental design changes to the invention. The present invention provides for an analysis on all textile machine types and requires no machine retrofit.
U.S. Pat. No. 4,110,654, issued to Andreas Paul, describes a sensor wherein a member vibrates when excited by a traveling yarn. That invention, however, does not include a signal processing means. In addition, the vibration frequency of the vibrating member is affected by the attachment of piezo type devices to the vibrating member. Failure to match a precise vibrating frequency to requirements can produce a high signal to noise ratio. While vibration isolation and vibration frequency differences of vibrating member and a base are determined in U.S. Pat. No. 4,110,654, there is no provision for these factors for upstream or downstream thread guides. Also, that invention suggests an enclosure to contain the effect of airborne noise, but, a mechanical enclosure may result in compaction of dust. The vibration means of the present invention is relatively insensitive to air noise, due to its low mass, small cross sectional area made possible by its simple design and to the independent, non-machine mounting of sensor assembly.
U.S. Pat. No. 4,381,803 issued to Weidmann, et al., is primarily directed to determining tension in weaving machines at various stages of weft insertion. That invention includes a motion responsive member consisting of a piezoelectrical system set into vibration by filament movement. The piezo element itself, however, can impact the vibration frequency, and the sensor does not control or define vibration frequency. In addition, the electronic circuit is not frequency filtered/tuned. The sensor signal amplitude is compared to fixed/set values in order to generate rectangular pulses, which are then matched to the machine via a rotating disk affixed to the machine. Also, no provision is made to control dust compaction.
U.S. Pat. No. 4,619,213 (Iimura, et al.), measures thread draw during stitch formation by wrapping thread on a pulley and sensing the rotation of the pulley. Angular momentum of the pulley prevents detection of rapid start and stop thread movement generated by textile machine take up action and stitch formation. The present invention, on the other hand, determines draw as a function of thread sensor signal and time.
U.S. Pat. No. 4,566,319 (Yamazaki, et al), entitled “PROCESS AND APPARATUS FOR MEASURING THERMAL SHRINKAGE PROPERTIES OF YARN” and U.S. Pat. No. 5,146,739 (Hellmut Lorenz) entitled “YARN FALSE TWIST TEXTURING PROCESS AND APPARATUS”, both describe devices for monitoring various criteria, including, the tension of thread or yarn to detect abnormal characteristics such as “false twisting” and shrinkage. The Yamazaki device uses pulleys to determine speed. As in U.S. Pat. No. 4,619,213, above, angular momentum imposes limits to speed change sensitivity. In addition, neither device detects the presence of a knot or the like.
U.S. Pat. No. 3,058,343 (G. H. Hutchens, et al.) entitled “APPARATUS FOR MONITORING YARN SURFACE DEFECTS”, and U.S. Pat. No. 2,881,833 (J. M. Hoffee) entitled “SEWING MACHINE ATTACHMENT FOR CUTTING SEAM BINDING” are of general interest only in that they disclose devices for monitoring and/or cutting threads or fabrics employed in textile production.
Prior literature also describes commercially available systems for monitoring the delivery of threaded yarn. Several such systems are produced and sold by Eltex of Sweden, Inc., Greer, S.C. In such systems, a hole, or eyelet, which may include a piezoelectric element, detects the presence or absence of thread or yarn.
There are combined commercial thread cutters and detectors available on the market such as those available from Fli Control and sold by Wilson Controls & Meters Co., Inc., Harrisburg, N.C. 28075.
Prior art sensors do not have specific means to sense knots and material inconsistencies, nor are they directed to speed sensitivity. Likewise, prior art electronic processing generally does not include means to determine or predict operating status based on average or trend changes for a multiplicity of duty cycles (stitches). The prior electronic processing art generally does not identify a time arid signal magnitude pattern generated by thread take up for a singular stitch/duty cycle based on sensed thread/fabric speed. Moreover, the prior art does not generate a numerical or voltage value which is a combined function of duty cycle time plus speed parameters for a (singular) duty cycle/stitch. In addition, the prior art generally does not address automatic machine diagnosis based on thread sensor input. U.S. Pat. No. 5,388,618, (Decock) for example, uses operator supplied input for machine diagnosis. The prior art does not address stitch count/production accounting using thread/fabric sensor output. The prior art does not produce an accurate measure of fabric processed wherein measure is derived from output of a thread sensor. Lastly, the prior art does not provide means to detect burrs on needles.
In detail, among the advantages provided by the sensor in the present invention over prior art sensors is that: 1) speed as well as tension is sensed, such that speed sensitivity is combined with electronic analysis revealing aspects of machine operation that are unavailable from the cited systems; and 2) unlike the patent disclosures cited herein, the present invention provides for controlled sensing of knots and fiber inconsistencies. Acceptable knot/inconsistency dimensions are set by sensor design.
The current electronic processor indicates and predicts malfunctions via several unique signal p
Bahta Kidest
Grant William
Woodbridge Richard C.
Woodbridge & Associates P.C.
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