CA2217424A1 - Piezoelectric broken-filament detection device and method of using same - Google Patents
Piezoelectric broken-filament detection device and method of using same Download PDFInfo
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- CA2217424A1 CA2217424A1 CA 2217424 CA2217424A CA2217424A1 CA 2217424 A1 CA2217424 A1 CA 2217424A1 CA 2217424 CA2217424 CA 2217424 CA 2217424 A CA2217424 A CA 2217424A CA 2217424 A1 CA2217424 A1 CA 2217424A1
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Abstract
A piezoelectric broken-filament detection device is used to detect breakage of a continuous material passing through a pathway. The device contains a support member and a sensor member and is positioned adjacent to but spaced from the pathway so that the continuous material passing through the pathway does not come into contact with the device.
The sensor member has a fixed end and a free end and has disposed on first facial surface thereof (1) a deflectable tab disposed on the free end, (2) a piezoelectric film operatively coupled to the deflectable tab, and (3) an internal switch-circuit element coupled to the piezoelectric film. As the continuous material passes through the pathway, broken ends formed upon breakage of the material comes into contact with the deflectable tab. The tab undergoes a deflection for each broken end which contacts it. Each deflection causes the piezoelectric film to generate a signal, each signal being processed by the internal switch-circuit element and actuating the internal switch-circuit element into a closed position.
The sensor member has a fixed end and a free end and has disposed on first facial surface thereof (1) a deflectable tab disposed on the free end, (2) a piezoelectric film operatively coupled to the deflectable tab, and (3) an internal switch-circuit element coupled to the piezoelectric film. As the continuous material passes through the pathway, broken ends formed upon breakage of the material comes into contact with the deflectable tab. The tab undergoes a deflection for each broken end which contacts it. Each deflection causes the piezoelectric film to generate a signal, each signal being processed by the internal switch-circuit element and actuating the internal switch-circuit element into a closed position.
Description
PIEZOELECTRIC BROKEN-FILAMENT DETECTION DEVICE
AND METHOD OF USING SAME
BACKGROU~D OF THE I~VF~TION
This invention relates to a device for detecting broken filaments. More particularly, this invention relates to a device which uses a piezoelectric film to detect and signal the presence of broken filaments and an internal switch-circuit element for responding to signals generated by the piezoelectric film.
Broken filaments are frequently produced during the operations involved in processing filaments into strands or strands into yarn.
Filament breakage may be due to excessive mechanical stresses produced during winding or twisting operations or to faulty filament structure caused by a problem in the manufacturing process.
Regardless of the cause of filament breakage, broken filaments, which tend to extend out of the strand or yarn at substantially right angles from the axis of the strand, generally degrade the quality of articles formed therefrom. For example, such articles tend to have gaps or discontinuities which substantially lower the stren~th of the articles. Thus, the presence of broken filaments has often led to considerable loss of time and product, particularly where large quantities of defective products have been formed from strands containing such filaments.
.
Therefore, it is desirable to provide a means for early detection of broken filaments so as to avoid loss of product and time and to increase production.
Impact detectors for detecting broken filaments are known in the art. Reference is made, for example, to U.S. Patent Nos. 3,635,413;
5,043,708; 3,800,162; 3,999,695; 4,677,387; and 4,610,707; all of the foregoing references being hereby incorporated by reference herein in their entirety. By means of a chanqe of resistance, switch closure, output voltage or current, and the like, impact detectors provide an indication that a change or event, e.g., filament breakage, has occurred.
The use of piezoelectric films in impact detectors for detecting broken filaments is also known in the art. Reference is made, for example, to U.S. Patent Nos. 5,136,202; 5,209,119; 4,393,647;
4,110,654; 4,258,S65; 5,089,741; 4,605,875 and 4,361,777; all of the foregoing references being hereby incorporated by reference herein in their entirety.
The use of piezoelectric films provides impact detectors with several benefits. For example, because piezoelectric films spontaneously generate a voltage pulse upon impact, impact detectors containing such films do not require voltage input or elaborate interface circuitry.
Furthermore, the low sensitivity to dirt and the mechanical robustness of piezoelectric films make these films particularly suitable for use in or on machines processing threads. In addition, because piezoelectric films are also relatively inexpensive and simple in structure, impact detectors using such films also tend to be relatively less expensive and less complicated than impact detectors which do not employ piezoelectric films.
Thus, impact detection devices containing piezoelectric films are continually desirable for use in detecting broken filaments.
In addition, it is desirable to provide a piezoelectric broken-filament detection device and a method of using same, wherein the detection device contains an internal switch-circuit element which can be activated by the signal generated by the piezoelectric film so to allow for the accounting of broken filaments over a specified period of time, which is important for reasons presented hereinbelow.
It is further desirable to provide a piezoelectric broken-filament detection device and a method of using same, wherein the detection device need not be in contact with the filament or thread being monitored prior to breakage of the filament or thread. Continuous contact with the thread or filament imposes continuous strain on the piezoelectric film and thereby causes the film to generate a multitude of signals which indicate nothing more than the continuous contact between the detection device and the passing, unbroken filament or thread. Such continuous contact between the - . CA 02217424 1997-10-27 filament or thread and the device subjects the film to undesirable levels of wear and tear, and complicates the circuitry needed to distinguish between those signals indicating filament/thread breakage and those signals which reflect the continuous contact.
Because filament breakage may be caused by the twisting, rewinding, and/or other mechanical handling of a strand, the number of broken filaments in the strand can serve as a guide to whether the handling equipment is operating properly and/or whether the quality of the fiber manufacturing process is sufficient. For example, the information obtained by means of a broken filament detector can be processed or recorded to determine if an abnormal number of defects occurs on a particular threadline, thus locating defective bobbins or defective prior processing e~uipment. Since the defective threadline is identified, it becomes possible to automatically repair the threadline, with resulting increase in efficiency and reduction in labor costs.
In addition, it is desirable to determine the effect which broken filaments have on the overall quality of a strand and the effect on filament breakage of changes in the manufacturing process or in the handling of the strand. These effects can be determined by determining the number of broken filaments per unit length of the strand to a high degree of accuracy and reliability. Since the number of broken filaments per unit length may be an indication of the quality of the filaments themselves, the accurate detection of such filaments can be an important factor in process control.
However, with the number of filament breaks per unit length of strand varying widely not only on a single bobbin, but also between a number of bobbins drawn from the same forming package, the breakage of filaments in a strand has been found to be of an extremely random nature. The random nature of filament breakage makes it difficult to know with certainty whether a particular measurement, taken from a relatively short strand length, accurately reflects the average amount of breakage occurring in the total strand.
Thus, in order to accurately monitor the lS quality of a filament-manufacturing process and/or the mechanical handling of filament strands, it would be desirable to provide a broken-filament detection device and a method of using same, wherein the detection device can be used in conjunction with a recorder or counter to provide an accurate measure of the degree of filament breakage occurring in a particular strand during a particular manufacturing or processing operation.
Accordingly, a primary object of this invention is to provide an impact detection device and a method of using same, wherein the detection device is capable of detecting filament breakage and providing an output signal indicative of this event.
A further object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the detection device uses a piezoelectric film to detect and signal the presence of broken filaments.
A still further object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the detection device contains an internal switch-circuit element.
Another object of this invention is to provide a broken-filament impact detection system and a method of using same, wherein the impact detection system is capable of obtaining an accurate count of the number of broken filaments occurring in a strand over a specified period of time.
Still another object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the impact detection device need not have continuous physical contact with a continuous material being monitored.
These and other objects which are achieved according to the present invention can be readily discerned from the following description.
SUMMARY OF THE INVENTION
The present invention provides a piezoelectric broken-filament detection device and a method of using same to detect brea~age of a continuous material moving through a pathway, wherein the device contains:
(A) a support member disposed adjacent to and spaced from the pathway such that the continuous material passing through the pathway does not contact the detection device; and (B) a sensor me~ber having a fixed end and an opposite free end, the fixed end being integral with the support member, wherein the sensor member further contains on a first facial surface thereof:
(1) a deflectable tab disposed on the free end of said sensor member, the deflectable tab being disposed to receive broken ends formed from the continuous material upon breakage thereof in the pathway, wherein the deflectable tab is adapted such that each impact of a broken end thereon causes the tab to undergo a deflection;
AND METHOD OF USING SAME
BACKGROU~D OF THE I~VF~TION
This invention relates to a device for detecting broken filaments. More particularly, this invention relates to a device which uses a piezoelectric film to detect and signal the presence of broken filaments and an internal switch-circuit element for responding to signals generated by the piezoelectric film.
Broken filaments are frequently produced during the operations involved in processing filaments into strands or strands into yarn.
Filament breakage may be due to excessive mechanical stresses produced during winding or twisting operations or to faulty filament structure caused by a problem in the manufacturing process.
Regardless of the cause of filament breakage, broken filaments, which tend to extend out of the strand or yarn at substantially right angles from the axis of the strand, generally degrade the quality of articles formed therefrom. For example, such articles tend to have gaps or discontinuities which substantially lower the stren~th of the articles. Thus, the presence of broken filaments has often led to considerable loss of time and product, particularly where large quantities of defective products have been formed from strands containing such filaments.
.
Therefore, it is desirable to provide a means for early detection of broken filaments so as to avoid loss of product and time and to increase production.
Impact detectors for detecting broken filaments are known in the art. Reference is made, for example, to U.S. Patent Nos. 3,635,413;
5,043,708; 3,800,162; 3,999,695; 4,677,387; and 4,610,707; all of the foregoing references being hereby incorporated by reference herein in their entirety. By means of a chanqe of resistance, switch closure, output voltage or current, and the like, impact detectors provide an indication that a change or event, e.g., filament breakage, has occurred.
The use of piezoelectric films in impact detectors for detecting broken filaments is also known in the art. Reference is made, for example, to U.S. Patent Nos. 5,136,202; 5,209,119; 4,393,647;
4,110,654; 4,258,S65; 5,089,741; 4,605,875 and 4,361,777; all of the foregoing references being hereby incorporated by reference herein in their entirety.
The use of piezoelectric films provides impact detectors with several benefits. For example, because piezoelectric films spontaneously generate a voltage pulse upon impact, impact detectors containing such films do not require voltage input or elaborate interface circuitry.
Furthermore, the low sensitivity to dirt and the mechanical robustness of piezoelectric films make these films particularly suitable for use in or on machines processing threads. In addition, because piezoelectric films are also relatively inexpensive and simple in structure, impact detectors using such films also tend to be relatively less expensive and less complicated than impact detectors which do not employ piezoelectric films.
Thus, impact detection devices containing piezoelectric films are continually desirable for use in detecting broken filaments.
In addition, it is desirable to provide a piezoelectric broken-filament detection device and a method of using same, wherein the detection device contains an internal switch-circuit element which can be activated by the signal generated by the piezoelectric film so to allow for the accounting of broken filaments over a specified period of time, which is important for reasons presented hereinbelow.
It is further desirable to provide a piezoelectric broken-filament detection device and a method of using same, wherein the detection device need not be in contact with the filament or thread being monitored prior to breakage of the filament or thread. Continuous contact with the thread or filament imposes continuous strain on the piezoelectric film and thereby causes the film to generate a multitude of signals which indicate nothing more than the continuous contact between the detection device and the passing, unbroken filament or thread. Such continuous contact between the - . CA 02217424 1997-10-27 filament or thread and the device subjects the film to undesirable levels of wear and tear, and complicates the circuitry needed to distinguish between those signals indicating filament/thread breakage and those signals which reflect the continuous contact.
Because filament breakage may be caused by the twisting, rewinding, and/or other mechanical handling of a strand, the number of broken filaments in the strand can serve as a guide to whether the handling equipment is operating properly and/or whether the quality of the fiber manufacturing process is sufficient. For example, the information obtained by means of a broken filament detector can be processed or recorded to determine if an abnormal number of defects occurs on a particular threadline, thus locating defective bobbins or defective prior processing e~uipment. Since the defective threadline is identified, it becomes possible to automatically repair the threadline, with resulting increase in efficiency and reduction in labor costs.
In addition, it is desirable to determine the effect which broken filaments have on the overall quality of a strand and the effect on filament breakage of changes in the manufacturing process or in the handling of the strand. These effects can be determined by determining the number of broken filaments per unit length of the strand to a high degree of accuracy and reliability. Since the number of broken filaments per unit length may be an indication of the quality of the filaments themselves, the accurate detection of such filaments can be an important factor in process control.
However, with the number of filament breaks per unit length of strand varying widely not only on a single bobbin, but also between a number of bobbins drawn from the same forming package, the breakage of filaments in a strand has been found to be of an extremely random nature. The random nature of filament breakage makes it difficult to know with certainty whether a particular measurement, taken from a relatively short strand length, accurately reflects the average amount of breakage occurring in the total strand.
Thus, in order to accurately monitor the lS quality of a filament-manufacturing process and/or the mechanical handling of filament strands, it would be desirable to provide a broken-filament detection device and a method of using same, wherein the detection device can be used in conjunction with a recorder or counter to provide an accurate measure of the degree of filament breakage occurring in a particular strand during a particular manufacturing or processing operation.
Accordingly, a primary object of this invention is to provide an impact detection device and a method of using same, wherein the detection device is capable of detecting filament breakage and providing an output signal indicative of this event.
A further object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the detection device uses a piezoelectric film to detect and signal the presence of broken filaments.
A still further object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the detection device contains an internal switch-circuit element.
Another object of this invention is to provide a broken-filament impact detection system and a method of using same, wherein the impact detection system is capable of obtaining an accurate count of the number of broken filaments occurring in a strand over a specified period of time.
Still another object of this invention is to provide a broken-filament impact detection device and a method of using same, wherein the impact detection device need not have continuous physical contact with a continuous material being monitored.
These and other objects which are achieved according to the present invention can be readily discerned from the following description.
SUMMARY OF THE INVENTION
The present invention provides a piezoelectric broken-filament detection device and a method of using same to detect brea~age of a continuous material moving through a pathway, wherein the device contains:
(A) a support member disposed adjacent to and spaced from the pathway such that the continuous material passing through the pathway does not contact the detection device; and (B) a sensor me~ber having a fixed end and an opposite free end, the fixed end being integral with the support member, wherein the sensor member further contains on a first facial surface thereof:
(1) a deflectable tab disposed on the free end of said sensor member, the deflectable tab being disposed to receive broken ends formed from the continuous material upon breakage thereof in the pathway, wherein the deflectable tab is adapted such that each impact of a broken end thereon causes the tab to undergo a deflection;
(2) a piezoelectric film operatively coupled to the deflectable tab so as to generate a signal for each deflection of the tab, the deflectable tab and said piezoelectric film each having a length sufficient to effectively detect the impact of a broken end; and (3) an internal switch-circuit element coupled to the piezoelectric film so as to process each signal generated by the film.
In preferred embodiments of the device of this invention, a screw is bolted to the first facial surface of the sensor member at the fixed end thereof. The screw extends over a portion of the deflectable tab and can be turned to apply tension to the tab so as to reduce false alarms caused by, e.g., air turbulence.
In the device of this invention, the piezoelectric film and the deflectable tab are mutually positioned such that deflection of the deflectable tab transmits a strain on the piezoelectric film which in turn causes the film to generate a signal which is then transmitted to the switch-circuit element. Preferably, the switch-circuit element will be disposed in an open position if no signal or an insufficient signal is generated by the piezoelectric film, and disposed in a closed position upon receipt of a signal or a sufficient signal from the piezoelectric film. The closing of the switch-circuit element can be designed to trigger a digital counter or brush recorder disposed in electrical communication therewith to allow for an accounting of the broken filaments occurring in a given strand over a specified period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a broken filament detection device within the scope of the present invention.
Fig. 2 is a simplified schematic top view of a broken filament detection system incorporating the detection device of this invention and a digital counter electrically coupled to the device.
D~TAILEP DESCRIPTION OF THE INVENTION
While, for purposes of convenience, filaments or thread are the particular continuous materials described herein in connection with the present invention, it should be understood that the present invention is applicable to any type of continuous material that is to be monitored for breakage. However, in preferred embodiments of the invention, the broken filament detection device and method of this invention are used in connection with materials having relatively high denier, e.g., carpet yarn.
As used herein, the term "broken end" or "broken-filament end" refers to the projecting end S of an individual filament or to a fragment which has completely separated from a broken filament.
As stated hereinabove, the device of this invention contains a support member and a sensor member. The support member is preferably adjacent to a pathway through which a continuous material passes, preferably in an endwise direction. The sensor member has disposed on a first facial surface thereof a deflectable tab, a piezoelectric film operatively coupled to the deflectable tab, and a switch-circuit element electrically coupled to the piezoelectric film.
The pathway of the continuous material is preferably provided by a guide means disposed in a package winding system. Preferred winders include those used in spinning devices for plastic filaments and in other yarn processing devices.
The support member is a rigid structure which serves as a base or clamp for a fixed end(s) of the sensor member. Although it can be formed of any rigid material, the support member is typically formed of a conducting material, e.g. a metal, or an insulating material, e.g., plastic. If composed of an electrically conducting material, the support member should be insulated from the piezoelectric film 80 as to avoid the short-circuiting of the film.
The sensor membe~ is preferably in the form of a cantilevered beam, wherein one end of the beam is integral with or otherwise affixed to the support member while the other end of the bean is free. The sensor member is preferably composed of a metal, more preferably, steel, such as, e.g., SAE
1095 spring steel, blue tempered.
The sensor member has a first facial surface on which is formed a deflectable tab, a piezoelectric film and an internal switch-circuit element.
The deflectable tab is disposed on the first facial surface portion of the free end of the sensor member. The deflectable tab is disposed to undergo a deflection each time is struck by a broken end formed when a continuous material breaks while passing through the adjacent pathway.
Preferably, the deflectable tab is relatively thin, with a preferred thickness of less than 1.0 millimeter.
A piezoelectric film is operatively coupled to the deflectable tab so as to generate output signals when the tab is struck by a broken-filament end. Preferably, the piezoelectric film is in the for~ of a strip which is bonded to the first facial surface of the sensor member, which, as stated hereinabove, is preferably in the form of a cantilever beam. Preferably, the positive side of the film is layered between the negative side of the film (which is grounded) and the first facial surface of the sensor member (which is also grounded).
The piezoelectric film may be bonded to the sensor member by means of an adhesive, e.g., a conventional stain gage adhesive. The adhesive may also function to electrically insulate the positive side of the film from the first facial surface of the sensor member. A lead may be bonded to the non-adhesive face of the film, e.g., by a suitable conductive epoxy.
The sensitivity of the piezoelectric film will generally depend on the length of the film.
The length of each of the deflectable tab and the piezoelectric film should be that which is sufficient to effectively detect the impact of the broken-end.
Preferably, the piezoelectric film used in the present invention will have a length of from about 1.1 centimeters to about 4.1 centimeters, more preferably from about 2.1 centimeters to about 4.1 centimeters, and most preferably from about 3.0 centimeters to about 4.1 centimeters.
The deflectable tab used in the present invention preferably has a length of from about 2.4 centimeters to about 6 centimeters, more preferably from about 3 centimeters to about 6 centimeters, and most preferably from about 4.5 centimeters to about 6 centimeters.
The thickness of the piezoelectric film will depend on several factors, including, for example, the particular piezoelectric properties desired, the specific application of the film, and the method used to deposit the film. For applications contemplated by the present invention, the piezoelectric film preferably has a thickness of about 0.003 inch.
Suitable piezoelectric films which can be used in the present invention include, e.g., those disclosed in U.S. Patent No. 5,136,202, which has been previously been incorporated herein in its entirety. Thus, a suitable piezoelectric film may be composed of, for example, a poled, polymeric piezomaterial such as poled polyvinylidene fluoride (PVDF); a poled copolymer of vinylidene fluoride (VDF), such as a copolymer of VDF with at least one of trifluoroethylene (TrFE), tetrafluoroethylene, hexafluoroethylene, or vinylidene chloride; a poled polymer of polyvinyl chloride; or a poled polymer of an acrylonitrile.
A particular preferred material for the film is polyvinylfluoride (PVF2).
As stated hereinabove, the piezoelectric film generates a signal upon a deflection of the deflectable tab, thus indicating that filament breakage has occurred. This signal is then detected and processed by the switch-circuit element coupled to the piezoelectric film. Any suitable switch-circuit element may be used to process the signals produced by the piezoelectric film.
As mentioned previously herein, the switch-circuit element is preferably adapted such that, in the absence of a signal or sufficient signal generated by the piezoelectric film, the switch-circuit element is disposed in an open position, whereas upon receipt thereof of a sufficient electrical signal generated by the piezoelectric film, the switch-circuit element is actuated into a closed position.
As also stated previously herein, the switch-circuit element may further be electrically coupled by means of an external circuit means to a brush recorder in order to determine the magnitude of a filament break or to a digital counter to determine the number of broken filaments. The external circuit means is preferably disposed on a circuit board which is affixed to a portion of the support member of the detection device.
The present invention is further directed to a detection system for detecting breakage of a continuous material. This system is composed of the detection device of this invention coupled to a control-function device such as a digital counter or a brush recorder.
Another aspect of the present invention is directed to an apparatus for forming and/or processing a continuous material, preferably filaments or threads, composed of a continuous-material forming or processing device coupled to the detection device or detection system of this invention, wherein the detection device is disposed adjacent to a pathway throuqh which the continuous material passes, further wherein the detection device is spaced apart from the pathway such that the continuous material passing through the pathway does not contact the detection device. Such an apparatus is preferably composed of a filament spinning device or other yarn processing device.
A further aspect of this invention is directed to a method for detecting breakage of a continuous material by means of the detection device of this invention. Broadly, this method involves:
(i) providing the piezoelectric broken-filament detection device of this invention;
(ii) positioning the device adjacent to but spaced from the pathway such that the continuous material passing through the pathway does not contact the device; and lS (iii) directing the continuous material through the pathway such that broken ends formed upon breakage of the material in the pathway contact the deflectable tab such that the tab undergoes a deflection for each broken end which contacts such tab, the deflection causing the piezoelectric film to generate a signal in response to the deflection, the signal being processed by the internal switch-circuit element and actuating the internal switch-circuit element into a closed position.
Typically, the "pathway" through which the yarn is passed in accordance with the present invention is the godet, wherein the yarn spins around the godet. Generally, the detection device of this invention will be positioned perpendicularly with respect to the godet since broken filaments will fly off the godet as yarns spins around it.
Typically, the detection device will be positioned no more than about 1.0 inch from the godet.
In some applications, e.g., the winding of multiple lengths of yarn onto a warp beam, a large number of detection devices within the scope of this invention may be used, with each device preferably being coupled to a digital counter, wherein each length of yarn is monitored by an individual detection device and counter system. Multiplexing circuitry may be provided to transfer the data in each of the corresponding latch circuits sequentially to corresponding storage locations, for example, in a microprocessor or computer.
The present invention will now be lS described by reference to Figs. 1 and 2 herein.
In Fig. 1, broken-filament detection device 100 includes a sensor member which is in the form of a flat cantilever beam 102 having a free end portion 106. Disposed on end portion 106 is deflectable tab 108 which is flat and extends outwardly. End portion 104 of beam 102 is affixed to support member 110 (shown in dashed lines).
Disposed on a first facial surface 112 of beam 102 is a deflectable portion 114, a piezoelectric film 116, and a switch-circuit element 118. At end portion 104 are disposed conductor leads 120 and 122. In a preferred embodiment of device 100, a plexiglas~ tab (not shown) i8 bolted to device 100 at 12~ and 126, and extend~ over a top portion of deflectable tab 108. Plexiglass tab h~s a screw at the opposite end which can be turned to apply tension to tab 108 ~o as to reduce false alar~s due to air turbulence.
CA 022l7424 l997-l0-27 In another embodiment of this invention, a control-function device (not shown), such as a digital counter or a brush recorder, may be electrically coupled to switch-circuit element 118 by means of the conductor leads 120 and 122.
Fig. 2 illustrates a detection system within the scope of this invention, wherein the system contains a detection device within the scope of this invention coupled to a control-function device which is preferably either a digital counter or a brush recorder. In ~ig. 2, "R1" and "R2"
represent first and second current-limiting resistors, respectively; "V" represents a power or voltage supply means; and "V~t" represents output voltage.
In Fig. 2, system 200 is composed of a detection device 202 and a control-function device 204 which are electrically connected to one another by means of an external circuit 206 having lead wires 208 and 210. Electrical signals generated by a piezoelectric film (not shown) in device 202 and processed by a switch-circuit element (not shown) in device 202 are conveyed through circuit 206 to device 204 via lead wires 208 and 210. If device 204 is a digital counter, the counter counts the signals generated by the piezoelectric film and switch-circuit element. Such counting will continue until a stop signal is received by device 204 from the switch-circuit element. The number of signals received by the counter will be characteristic of and will identify the defective threadline. This information can be used directly or can be converted to another form as desired.
EXPERIMENTAL
Comparative Examples A and B and Invention Examples 1 and 2 In Comparative Examples A and B and Examples 1 and 2, four cantilevered sensor members coated with piezoelectric films of varying film lengths (as measured from front edge of silver ink) and deflectable tabs of different lengths and thicknesses were tested for the ability thereof to detect broken filaments. In the examples below, the detection device was positioned perpendicularly with respect to the godet.
In Comparative Example A, the piezoelectric film had a length of about 1.1 centimeters while the deflectable tab had a thickness of about 0.003 inch and a length of about 2.4 centimeters.
In Comparative Example B, the piezoelectric film had a length of about 1.1 centimeters, while the deflectable tab had a thickness of about 0.003 inch and a length of about 4.5 centimeters.
In Invention Example 1, the piezoelectric film had a length of about 2.1 centimeters while the deflectable tab had a thickness of about 0.003 inch and a length of about 4.5 centimeters.
In Invention Example 2, the piezoelectric film had a length of about 4.1 centimeters and the deflectable tab had a thickness of about 0.003 inch and a length of about S.O centimeters.
Only the detection devices of Invention Examples 1 and 2 detected filaments. The device in Example 2 had a 50~ detection rate and was more sensitive than the device in Example 1. The device in Example 1 was damaged when the threadline broke.
With a chart recorder connected in parallel to the digital counter, the detection rate for all the devices increased dramatically.
The devices in Examples 1 and 2 were also more sensitive to air turbulence than were the devices in Comparative Examples A and B.
While there are shown or described present preferred embodiments of the invention, it is to be understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.
In preferred embodiments of the device of this invention, a screw is bolted to the first facial surface of the sensor member at the fixed end thereof. The screw extends over a portion of the deflectable tab and can be turned to apply tension to the tab so as to reduce false alarms caused by, e.g., air turbulence.
In the device of this invention, the piezoelectric film and the deflectable tab are mutually positioned such that deflection of the deflectable tab transmits a strain on the piezoelectric film which in turn causes the film to generate a signal which is then transmitted to the switch-circuit element. Preferably, the switch-circuit element will be disposed in an open position if no signal or an insufficient signal is generated by the piezoelectric film, and disposed in a closed position upon receipt of a signal or a sufficient signal from the piezoelectric film. The closing of the switch-circuit element can be designed to trigger a digital counter or brush recorder disposed in electrical communication therewith to allow for an accounting of the broken filaments occurring in a given strand over a specified period of time.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a broken filament detection device within the scope of the present invention.
Fig. 2 is a simplified schematic top view of a broken filament detection system incorporating the detection device of this invention and a digital counter electrically coupled to the device.
D~TAILEP DESCRIPTION OF THE INVENTION
While, for purposes of convenience, filaments or thread are the particular continuous materials described herein in connection with the present invention, it should be understood that the present invention is applicable to any type of continuous material that is to be monitored for breakage. However, in preferred embodiments of the invention, the broken filament detection device and method of this invention are used in connection with materials having relatively high denier, e.g., carpet yarn.
As used herein, the term "broken end" or "broken-filament end" refers to the projecting end S of an individual filament or to a fragment which has completely separated from a broken filament.
As stated hereinabove, the device of this invention contains a support member and a sensor member. The support member is preferably adjacent to a pathway through which a continuous material passes, preferably in an endwise direction. The sensor member has disposed on a first facial surface thereof a deflectable tab, a piezoelectric film operatively coupled to the deflectable tab, and a switch-circuit element electrically coupled to the piezoelectric film.
The pathway of the continuous material is preferably provided by a guide means disposed in a package winding system. Preferred winders include those used in spinning devices for plastic filaments and in other yarn processing devices.
The support member is a rigid structure which serves as a base or clamp for a fixed end(s) of the sensor member. Although it can be formed of any rigid material, the support member is typically formed of a conducting material, e.g. a metal, or an insulating material, e.g., plastic. If composed of an electrically conducting material, the support member should be insulated from the piezoelectric film 80 as to avoid the short-circuiting of the film.
The sensor membe~ is preferably in the form of a cantilevered beam, wherein one end of the beam is integral with or otherwise affixed to the support member while the other end of the bean is free. The sensor member is preferably composed of a metal, more preferably, steel, such as, e.g., SAE
1095 spring steel, blue tempered.
The sensor member has a first facial surface on which is formed a deflectable tab, a piezoelectric film and an internal switch-circuit element.
The deflectable tab is disposed on the first facial surface portion of the free end of the sensor member. The deflectable tab is disposed to undergo a deflection each time is struck by a broken end formed when a continuous material breaks while passing through the adjacent pathway.
Preferably, the deflectable tab is relatively thin, with a preferred thickness of less than 1.0 millimeter.
A piezoelectric film is operatively coupled to the deflectable tab so as to generate output signals when the tab is struck by a broken-filament end. Preferably, the piezoelectric film is in the for~ of a strip which is bonded to the first facial surface of the sensor member, which, as stated hereinabove, is preferably in the form of a cantilever beam. Preferably, the positive side of the film is layered between the negative side of the film (which is grounded) and the first facial surface of the sensor member (which is also grounded).
The piezoelectric film may be bonded to the sensor member by means of an adhesive, e.g., a conventional stain gage adhesive. The adhesive may also function to electrically insulate the positive side of the film from the first facial surface of the sensor member. A lead may be bonded to the non-adhesive face of the film, e.g., by a suitable conductive epoxy.
The sensitivity of the piezoelectric film will generally depend on the length of the film.
The length of each of the deflectable tab and the piezoelectric film should be that which is sufficient to effectively detect the impact of the broken-end.
Preferably, the piezoelectric film used in the present invention will have a length of from about 1.1 centimeters to about 4.1 centimeters, more preferably from about 2.1 centimeters to about 4.1 centimeters, and most preferably from about 3.0 centimeters to about 4.1 centimeters.
The deflectable tab used in the present invention preferably has a length of from about 2.4 centimeters to about 6 centimeters, more preferably from about 3 centimeters to about 6 centimeters, and most preferably from about 4.5 centimeters to about 6 centimeters.
The thickness of the piezoelectric film will depend on several factors, including, for example, the particular piezoelectric properties desired, the specific application of the film, and the method used to deposit the film. For applications contemplated by the present invention, the piezoelectric film preferably has a thickness of about 0.003 inch.
Suitable piezoelectric films which can be used in the present invention include, e.g., those disclosed in U.S. Patent No. 5,136,202, which has been previously been incorporated herein in its entirety. Thus, a suitable piezoelectric film may be composed of, for example, a poled, polymeric piezomaterial such as poled polyvinylidene fluoride (PVDF); a poled copolymer of vinylidene fluoride (VDF), such as a copolymer of VDF with at least one of trifluoroethylene (TrFE), tetrafluoroethylene, hexafluoroethylene, or vinylidene chloride; a poled polymer of polyvinyl chloride; or a poled polymer of an acrylonitrile.
A particular preferred material for the film is polyvinylfluoride (PVF2).
As stated hereinabove, the piezoelectric film generates a signal upon a deflection of the deflectable tab, thus indicating that filament breakage has occurred. This signal is then detected and processed by the switch-circuit element coupled to the piezoelectric film. Any suitable switch-circuit element may be used to process the signals produced by the piezoelectric film.
As mentioned previously herein, the switch-circuit element is preferably adapted such that, in the absence of a signal or sufficient signal generated by the piezoelectric film, the switch-circuit element is disposed in an open position, whereas upon receipt thereof of a sufficient electrical signal generated by the piezoelectric film, the switch-circuit element is actuated into a closed position.
As also stated previously herein, the switch-circuit element may further be electrically coupled by means of an external circuit means to a brush recorder in order to determine the magnitude of a filament break or to a digital counter to determine the number of broken filaments. The external circuit means is preferably disposed on a circuit board which is affixed to a portion of the support member of the detection device.
The present invention is further directed to a detection system for detecting breakage of a continuous material. This system is composed of the detection device of this invention coupled to a control-function device such as a digital counter or a brush recorder.
Another aspect of the present invention is directed to an apparatus for forming and/or processing a continuous material, preferably filaments or threads, composed of a continuous-material forming or processing device coupled to the detection device or detection system of this invention, wherein the detection device is disposed adjacent to a pathway throuqh which the continuous material passes, further wherein the detection device is spaced apart from the pathway such that the continuous material passing through the pathway does not contact the detection device. Such an apparatus is preferably composed of a filament spinning device or other yarn processing device.
A further aspect of this invention is directed to a method for detecting breakage of a continuous material by means of the detection device of this invention. Broadly, this method involves:
(i) providing the piezoelectric broken-filament detection device of this invention;
(ii) positioning the device adjacent to but spaced from the pathway such that the continuous material passing through the pathway does not contact the device; and lS (iii) directing the continuous material through the pathway such that broken ends formed upon breakage of the material in the pathway contact the deflectable tab such that the tab undergoes a deflection for each broken end which contacts such tab, the deflection causing the piezoelectric film to generate a signal in response to the deflection, the signal being processed by the internal switch-circuit element and actuating the internal switch-circuit element into a closed position.
Typically, the "pathway" through which the yarn is passed in accordance with the present invention is the godet, wherein the yarn spins around the godet. Generally, the detection device of this invention will be positioned perpendicularly with respect to the godet since broken filaments will fly off the godet as yarns spins around it.
Typically, the detection device will be positioned no more than about 1.0 inch from the godet.
In some applications, e.g., the winding of multiple lengths of yarn onto a warp beam, a large number of detection devices within the scope of this invention may be used, with each device preferably being coupled to a digital counter, wherein each length of yarn is monitored by an individual detection device and counter system. Multiplexing circuitry may be provided to transfer the data in each of the corresponding latch circuits sequentially to corresponding storage locations, for example, in a microprocessor or computer.
The present invention will now be lS described by reference to Figs. 1 and 2 herein.
In Fig. 1, broken-filament detection device 100 includes a sensor member which is in the form of a flat cantilever beam 102 having a free end portion 106. Disposed on end portion 106 is deflectable tab 108 which is flat and extends outwardly. End portion 104 of beam 102 is affixed to support member 110 (shown in dashed lines).
Disposed on a first facial surface 112 of beam 102 is a deflectable portion 114, a piezoelectric film 116, and a switch-circuit element 118. At end portion 104 are disposed conductor leads 120 and 122. In a preferred embodiment of device 100, a plexiglas~ tab (not shown) i8 bolted to device 100 at 12~ and 126, and extend~ over a top portion of deflectable tab 108. Plexiglass tab h~s a screw at the opposite end which can be turned to apply tension to tab 108 ~o as to reduce false alar~s due to air turbulence.
CA 022l7424 l997-l0-27 In another embodiment of this invention, a control-function device (not shown), such as a digital counter or a brush recorder, may be electrically coupled to switch-circuit element 118 by means of the conductor leads 120 and 122.
Fig. 2 illustrates a detection system within the scope of this invention, wherein the system contains a detection device within the scope of this invention coupled to a control-function device which is preferably either a digital counter or a brush recorder. In ~ig. 2, "R1" and "R2"
represent first and second current-limiting resistors, respectively; "V" represents a power or voltage supply means; and "V~t" represents output voltage.
In Fig. 2, system 200 is composed of a detection device 202 and a control-function device 204 which are electrically connected to one another by means of an external circuit 206 having lead wires 208 and 210. Electrical signals generated by a piezoelectric film (not shown) in device 202 and processed by a switch-circuit element (not shown) in device 202 are conveyed through circuit 206 to device 204 via lead wires 208 and 210. If device 204 is a digital counter, the counter counts the signals generated by the piezoelectric film and switch-circuit element. Such counting will continue until a stop signal is received by device 204 from the switch-circuit element. The number of signals received by the counter will be characteristic of and will identify the defective threadline. This information can be used directly or can be converted to another form as desired.
EXPERIMENTAL
Comparative Examples A and B and Invention Examples 1 and 2 In Comparative Examples A and B and Examples 1 and 2, four cantilevered sensor members coated with piezoelectric films of varying film lengths (as measured from front edge of silver ink) and deflectable tabs of different lengths and thicknesses were tested for the ability thereof to detect broken filaments. In the examples below, the detection device was positioned perpendicularly with respect to the godet.
In Comparative Example A, the piezoelectric film had a length of about 1.1 centimeters while the deflectable tab had a thickness of about 0.003 inch and a length of about 2.4 centimeters.
In Comparative Example B, the piezoelectric film had a length of about 1.1 centimeters, while the deflectable tab had a thickness of about 0.003 inch and a length of about 4.5 centimeters.
In Invention Example 1, the piezoelectric film had a length of about 2.1 centimeters while the deflectable tab had a thickness of about 0.003 inch and a length of about 4.5 centimeters.
In Invention Example 2, the piezoelectric film had a length of about 4.1 centimeters and the deflectable tab had a thickness of about 0.003 inch and a length of about S.O centimeters.
Only the detection devices of Invention Examples 1 and 2 detected filaments. The device in Example 2 had a 50~ detection rate and was more sensitive than the device in Example 1. The device in Example 1 was damaged when the threadline broke.
With a chart recorder connected in parallel to the digital counter, the detection rate for all the devices increased dramatically.
The devices in Examples 1 and 2 were also more sensitive to air turbulence than were the devices in Comparative Examples A and B.
While there are shown or described present preferred embodiments of the invention, it is to be understood that the invention is not limited thereto, but may be otherwise variously embodied and practiced within the scope of the following claims.
Claims (12)
1. A method for detecting breakage of a continuous material passing through a pathway, comprising the steps of:
(i) providing a piezoelectric broken-filament detection device;
(ii) positioning the device adjacent to but spaced from said pathway such that the continuous material passing through the pathway does not contact the device, wherein the device comprises:
(A) a support member disposed adjacent to and spaced from said pathway such that the continuous material passing through the pathway does not contact the detection device; and (B) a sensor member having a fixed end and an opposite free end, the fixed end being integral with the support member, wherein the sensor member further contains on a first facial surface thereof:
(1) a deflectable tab disposed on the free end of said sensor member, the deflectable tab being disposed to receive broken ends formed from the continuous material upon breakage thereof in the pathway, wherein the deflectable tab is adapted such that each impact of a broken end thereon causes the tab to undergo a deflection;
(2) a piezoelectric film operatively coupled to the deflectable tab so as to generate a signal for each deflection of said tab, said deflectable tab and said piezoelectric film each having a length sufficient to effectively detect the impact of a broken end; and (3) an internal switch-circuit element coupled to the piezoelectric film so as to process each signal generated by said film; and (iii) directing said continuous material through said pathway.
(i) providing a piezoelectric broken-filament detection device;
(ii) positioning the device adjacent to but spaced from said pathway such that the continuous material passing through the pathway does not contact the device, wherein the device comprises:
(A) a support member disposed adjacent to and spaced from said pathway such that the continuous material passing through the pathway does not contact the detection device; and (B) a sensor member having a fixed end and an opposite free end, the fixed end being integral with the support member, wherein the sensor member further contains on a first facial surface thereof:
(1) a deflectable tab disposed on the free end of said sensor member, the deflectable tab being disposed to receive broken ends formed from the continuous material upon breakage thereof in the pathway, wherein the deflectable tab is adapted such that each impact of a broken end thereon causes the tab to undergo a deflection;
(2) a piezoelectric film operatively coupled to the deflectable tab so as to generate a signal for each deflection of said tab, said deflectable tab and said piezoelectric film each having a length sufficient to effectively detect the impact of a broken end; and (3) an internal switch-circuit element coupled to the piezoelectric film so as to process each signal generated by said film; and (iii) directing said continuous material through said pathway.
2. A method according to claim 1, wherein each signal generated by said film actuates said internal switch-circuit element into a closed position.
3. A method according to claim 1, wherein in the absence of a signal from said film, said internal switch-element is disposed in an open position.
4. A method according to claim 1, wherein said sensor member is a cantilevered beam.
5. A method according to claim 1, wherein said deflectable tab has a length of from about 2.4 to about 6.0 centimeters.
6. A method according to claim 1, wherein said piezoelectric film comprises a material selected from the group consisting of polyvinylidene fluoride; a copolymer of vinylidene fluoride; a copolymer comprising vinylidene fluoride and at least one of trifluoroethylene, tetrafluoroethylene, hexafluoroethylene, and vinylidene chloride; a polymer of polyvinylchloride; and a polymer of acrylonitrile.
7. A method according to claim 6, wherein said piezoelectric film comprises polyvinylfluoride.
8. A method according to claim 1, wherein said piezoelectric film has a thickness of about 0.003 inch.
9. A method according to claim 1, wherein said piezoelectric film has a length of from about 1.1 to about 4.1 centimeters.
10. A method according to claim 1, wherein said device further comprises an external circuit means coupled to said switch-circuit element.
11. A method according to claim 10, wherein said device further comprises a control-function device electrically coupled to the switch-circuit element by means of the external circuit means.
12. A method according to claim 11, wherein said control-function device is a digital counter or a brush recorder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81269097A | 1997-03-06 | 1997-03-06 | |
| US08/812,690 | 1997-03-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2217424A1 true CA2217424A1 (en) | 1998-09-06 |
Family
ID=25210351
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2217424 Abandoned CA2217424A1 (en) | 1997-03-06 | 1997-10-27 | Piezoelectric broken-filament detection device and method of using same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2217424A1 (en) |
-
1997
- 1997-10-27 CA CA 2217424 patent/CA2217424A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| MX9710009A (en) | 1998-09-30 |
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