WO2017055961A1

WO2017055961A1 - A device and a method for sensing end of warp yarn or tape on a fabric weaving loom

Info

Publication number: WO2017055961A1
Application number: PCT/IB2016/055570
Authority: WO
Inventors: Siddharth LOHIA
Original assignee: Siddharth LOHIA
Priority date: 2015-10-01
Filing date: 2016-09-19
Publication date: 2017-04-06
Also published as: CN108138397A; TWI608139B; BR112018006119B1; EP3356586B1; EP3356586A1; CN108138397B; BR112018006119A2; TW201713814A

Abstract

The invention discloses a device for sensing end of warp yarn on a circular weaving machine (CWM). It has an improved drop wire and a device to detect the end of a running yarn on a CWM. The device also incorporates an electric circuit which is kept open during normal working of the loom. When a yarn break is detected by a yarn detection means which is also a part of the device, the electric circuit is completed and a notification is sent to the loom operator and the CWM is stopped. The invention is particularly suitable in dusty environment in which CWMs typically operate. The drop wire is provided with an electrically conducting first element having a spatially curved external surface. The device also incorporates a set of electrically conducting second elements having curved internal surfaces. Upon the loss of elevation of the first elements, the first and second elements come in electrical contact with each other, thereby completing the electric circuit and causing a signal to be sent indicating yarn breakage.

Description

A DEVICE AND A METHOD FOR SENSING END OF WARP YARN OR TAPE ON A FABRIC WEAVING LOOM

FIELD OF THE INVENTION

Device of the invention relates to weaving machines, containing warp and weft yarns/tapes for fabric weaving on circular weaving machines, more precisely, sensing end of warp yarn/tape during fabric production.

BACKGROUND INFORMATION

The circular weaving loom or machine (CWM) is designed to weave endless tubular or flat fabric using PP, HDPE, LLDPE yarn/tape or other blends of polyolefin (Figure 1).

The warp yarns/tapes are fed to the weaving machine-from more than one creel via rollers. This ensures uniform warp tension, excellent fabric quality, and trouble-free handling (Figures 2 & 3).

In conventional looms, six or more shuttles running on a reed ring are provided for carrying the weft bobbins. During the fabric production, warp bobbins can be changed easily and quickly without shutting down the CWM. This is done by tying into a knot the two ends - one end being that of the exhausted bobbin and the other being that of the fresh yarn. Therefore, when yarn/tape on a bobbin is coming to end, the bobbin needs replacement with a new bobbin. If this is not done within stipulated time, the warp yarn/tape on the bobbin becomes loose as tension drops due to continuity break. As this is done under observation of the operator, this whole operation is dependent on operator skill and prone to operator error. Furthermore, the loose yarn/tape may possibly entangle with other nearby yarns/tapes coming from adjacent bobbins thereby damaging section of the running fabric. Thus, one of the drawbacks of the existing systems is its requirement to regularly monitor bobbin exhaustion by operator. Similarly, another drawback of the existing systems is that when the ends of the warp are noticed, the machine needs to be stopped immediately such that the ends of the warp tapes are not allowed to reach reed ring section of the weaving machine.

One of the popular methods to sense yarn ends incorporates the use of a drop wire (Figures 4A and 4B). Drop wire systems consist of a gravity-controlled 'drop wire' made of metals such as stainless steel through which the tape used for fabric making passes. When warp yarn/tape ends, yarn/tape loses it tension which causes it to slag causing drop wire to fall down. In this case, operator observes slag in yarn/tape and stops the machine to change the empty or semi filled tube with new bobbin.

There are certain limitations of this system which are of practical significance. First, in running machine operator would require to keep monitoring for any warp end, which is very difficult when number of machines operated by operator is more than one or operator loses his attention in between. Second, when number of warp bobbins getting empty is higher, in that case observing all of them is difficult, meanwhile running machine produces waste fabric which cannot be used further.

Nowadays, there is growing trend of filler addition to polyolefin tapes. The filler content tends to generate powdery dust particulates during fabric weaving operation. These dust particles settle on any available surface in the vicinity of the loom. The settled dust has the potential to disrupt the electronic/electrical sensor functioning, hampering the loom operations. There are yarn end detection systems that are automated and use electric circuits. However, it has been found that these systems are susceptible to frequent malfunctioning, especially in the dusty environs.

There is therefore a need to provide an improved drop wire and a system to detect yarn end and provide a notification of it to the operator, which will work unhampered even in dusty environment.

OBJECTS OF THE INVENTION

Accordingly, one of the objects of the present invention is to provide an automated system for sensing warp end.

Another object of the invention is to provide an automated system for detecting warp end which will work robustly in dusty environment. A further object of the invention is to provide an improved drop wire for the purpose of detection of warp end.

Another object of the present invention is to provide a system that reduces the wastage of weaved fabric and machine downtime.

SUMMARY OF THE INVENTION

The invention discloses an improved drop wire and a device to detect the end of a running yarn on a CWM used to make endless tubular fabric. The device of the invention also discloses an electric circuit which is kept open during normal working of the loom - that is when all yarns are running unbroken. The device is so designed that upon detection of a yarn end (due to yarn breakage or due to the yarn package running out of yarn) by a yarn detection means that is also a part of the device, the electric circuit is completed and a notification is sent to the loom operator. The invention is particularly suitable in dusty environment in which CWMs typically operate.

The invention utilizes an improved drop wire (6) which maintains its normal operating position by hanging by the running yarn that passes through a loop provided at one end of the drop wire. The drop wire is provided with an electrically conducting first element having a spatially curved external surface. Breakage of the running yarn causes loss of tension in the yarn, causing the drop wire to lose its elevation rapidly. The device of the invention also incorporates a set of electrically conducting second elements having a curved internal surface. Upon the loss of elevation, the first and second elements come in electrical contact with each other, thereby completing an electric circuit and consequently causing a signal to be sent to the operator of the loom indicating yarn breakage. Drop wires (6) are provided on every individual warp yarn/tape which is fed to the central reed ring section.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a schematic of loom used to manufacture woven fabric

Figure 2 shows a schematic of warp yarn/tape travel path in a loom

Figure 3 shows woven fabric and a tube form of it

Figure 4A and 4B show the open circuit and closed circuit positions, respectively, of the typical drop-wire type device of the prior art

Figures 5 A and 5B show the configuration of second elements

Figure 6A shows the drop wire with first element

Figures 6B, 6C, and 6D show second elements along with configuration of inner surfaces

Figure 7 shows details of the inner surfaces of a second element

List of parts:

Creel Bracket (1) Outer Surface (6C)

Inlet Motor (2) Second elements (7)

Roller (3) Physical gap (7 A) Woven fabric (4) Inner Curved shaped surface (7B)

Bobbin (5) Single surface (7C)

Drop wire (6) Sub-surface (7D)

Loop (6A) Point (7E)

First element (6B) Edge (7F)

Electronic Circuit (8) Yarn (9)

DETAILED DESCRIPTION OF THE INVENTION

Woven fabric for use in making bags for storing materials such as grains, cement, etc. is made from yarn/tape of PP, FIDPE, LLDPE or other blends of polyolefin. As shown in Figure 1, a circular weaving machine/loom (CWMs) that makes tubular fabric for making such bags deploys a number of bobbins. Figure 2 shows the typical yarn travel path in a CWM. As discussed earlier, for a number of reasons, yarn gets broken during the loom operation. The device disclosed in the invention allows detection of ends of a broken yarn/tape so that the CWM may be stopped in order and a signal is sent to the operator on duty to avoid entanglement of the broken yarn/tape with other yarns/tapes operational on the CWM.

As disclosed in the summary section, the key purpose of the device of the invention is to detect the breakage or end of a running yarn and inform the loom operator of its occurrence. This is achieved by providing the following three key elements in the device: a means to detect the yarn breakage, an electric circuit, and a notification means. It also should be noted that the CWMs operate in an environment where a substantial amount of particulate matter (dust) is generated as a result of loom operation. These particles settle on any available surface in the vicinity of the loom. The settled dust which is electrically non-conductive has the potential to hamper the loom operations. In the case of systems to detect yarn ends, where electric circuits are employed, the smooth working of such circuits may be hampered by such dust. One of the key aspects of the device of the invention is that it works effectively regardless of the dusty environments within which they are deployed.

The present invention discloses a device for sensing end of warp yarn or tapes on an automated fabric weaving loom and notifying the instance of yarn breakage to the operator. It comprises a yarn end detection means to detect the breakage of or a slack in running yarn, an electric circuit, and a notification means to notify breakage of or slack in yarn.

In one aspect of the invention, the yarn end detection means comprises an improved weighted drop wire (6) (Figures 4A and 6A) with an eye (6A) at its one end through which the running warp yarn/tape (9) passes, and which is held in substantially upheld position by the tension in the running yarn (9). An electrically conducting first element (6B) is attached fixedly to the drop at a predetermined distance 'h' (Figure 4A) from the eye (6A). During the operation of the loom, if a yarn (9) breaks, the specific drop wire (6) that was supported by the yarn (9), before its breaking, drops (Figure 4B) from its previously upheld position. It should be noted that during the normal operations of a loom, the drop wire (6) moves vertically, in small amounts, from its normal operating position. This is due to irregularity in the package's winding quality, leading to variation in the yarn tension. However, such vertical positional variation is normal and not unexpected. Whenever there's such accepted type of positional variation, the drop wire (6) regains its normal working position in a matter of fraction of seconds.

In the instance of an actual breakage (or indeed when a package comes to an end, thereby running out of yarn), the drop of the drop wire (6) from its normal operating position is substantial and irrecoverable. The drop wire (6) drops vertically by a substantial distance from its normal operating position on substantial loss of tension in the running yarn (6) - sensing of the irrecoverable drop of the drop wire (6) represents yarn end detection. A pair of electrically conducting second elements (7) (see Figures 5A/5B) is provided as a part of the electric circuit that is referred to earlier. Upon the detection of a yarn breakage, as the specific drop wire (6) drops (Figure 4B), it brings the first element (6B) in electrical contact with corresponding second elements (7), thereby closing the electric switch/loop and consequently completing the electric circuit (Figure 5B). As also shown in Figures 5A and 5B, in another aspect of the invention, the components of the electric circuit are the first elements (6B), second elements (7), an electronic circuit (8) that electrically connects two second elements (7) of any pair of the second elements (7) at one end of the second elements (7), and a source of electric power. It further comprises an electric switch or a loop that is yarn-dust-proof. During the normal working operation of the loom, the electric switch/loop remains Open'. The device is so designed that upon detection of a yarn breakage or a yarn end, the electric switch/loop closes effectively thereby completing the electric circuit - regardless of the presence of dusty environment. Upon closure of the electric circuit, an alarm is raised and a signal is sent to the operator indicating the yarn breakage.

As discussed earlier, the drop wire (6) supports a first element that has an electrically conducting outer surface (6C). The outer surface (6C) of the first element (6B) is spatially curved (Figure 6A), preferably substantially in the form of a cone of any type. The outer surface (6C) may have serrations that run substantially longitudinally. The yarn-dust-proof electric switch/loop comprises a pair of electrically conducting second elements (7). As shown in Figures 6B and 6C, the second elements (7) are provided with inner curved shaped surfaces (also termed as inner surfaces or inner shaped surfaces) (7B) with a shape that corresponds to the outer surface (6C) of the first elements (6B). The term 'corresponds' mentioned above refers to the correspondence between the outer surface (6C) of the first element (6B) and the shaped inner surface (7B) of the second element (7), and is to be understood in the context of electrical connection. The outer surface (6C) of the first element (6B) and the corresponding inner surface (7B or 7C) on the second element do not have to be 'exactly matching' - that is they do not need to be in full contact with each other. By correspondence it is meant that there simply needs to be sufficient contact so that the electric switch/loop is closed effectively. It is known that the dust tends to settle on surfaces that are, among other characteristics, devoid of geometric features such as points and sharp edges. In the view of this, in one aspect of the invention, the inner surfaces (7B) of the second elements (7) are provided with points and/or sharp edges. Some of these are illustrated in Figure 7.

As shown in Figures 5A and 5B, in one embodiment of the invention, the second elements (7) are in the form of a strip or a plate on which are provided the inner curved shaped surfaces (7B). When positioned across from each other, these plates, with the inner curved shaped surfaces (7B) facing the inner curved shaped surfaces (7B) of the other second element (7) from the pair of second elements, they form receptors into which the first elements (6B) fall when the drop wire (6) loses its elevation substantially. As can be seen from Figure 5, there is a physical gap (7 A) between the two shaped edges that face each other. It is this gap (7 A) that keeps the electric switch/loop in an open state during the normal working condition of the loom. At the same time, the gap (7 A) is so designed that the drop wire (6) passes through it in its normal working position without closing the electric loop.

The curve of the outer surface (6C) of the first element (6B) may of any shape, however it should be such that when the drop wire (6) drops from its normal working position, the first element (6B)— owing to the curvature of its outer surface (6C)— goes into the gap (7 A) between the inner shaped curved surfaces (7B) of the two parts of the second elements (7) easily. The curvature of the outer surface (6C) should be of such shape that upon resumption of the tension in the yarn, when the drop wire (6) is pulled up back to its own normal working position due to the tension in the yarn, this upward movement of the drop wire (6) is carried out unhindered.

The inner curved shaped surfaces (7B) of the second elements (7) may be made of a single surface (7C) (Figure 6D) or multiple sub-surfaces (7D) (Figures 6B/6C). In the case there are multiple sub-surfaces (7D), the junctions between any two sub-surfaces (7D) are preferably in the form of a point (7E) or an edge (7F) (see Figure 7) that is preferably sharp.

Formation of points or sharp edges (7E and/or 7F) is important in order to not allow dust to settle on at least some part of the curved shaped inner surfaces (7B). This is of crucial importance as it allows an effective electric contact to be established with ease between at least some parts of the curved outer surface (6C) of the first element (6B) and the inner curved shaped surface (7B) of the second elements (7) at any time when the drop wire (6) has fallen from its normal operating position.

The vertical distance 'h' (Figure 4A) at which the first element (6B) is located from the running yarn (9) that supports a particular drop wire (6) depends on the overall configuration of the system of yarns. The distance should be such that upon yarn breakage detection, the circuit is closed within a reasonably short time period. The distance should also be such that there is no false alarm raised in situations where there is temporary loss of tension. However, there may be exceptional circumstances, where the loss of tension is due to abnormal or unexpected slack in an unbroken running yarn, where the drop wire (6) may drop sufficiently so that the circuit closes.

One feature of the present invention is its ability to distinguish between temporary slack in the warp and permanent breakage in the yarn/tape (9). In the experience of the inventor, in the situations where such exceptional situations occur, the yarn (9) resumes its normal operation once the slack is eliminated by the ongoing movement of the yarn (9). This may take a duration as small as 0.1 seconds and up to 2 seconds. Under such circumstances, it would be undesirable if the CWM shuts down simply because there was a circuit closure (which is typically indicative of yarn end detection).

In order to overcome such exceptional but potentially real problems, the device is provided with time monitoring facility. Time from any given closure of circuit is monitored and noted. In the case where there's no opening up of the circuit following from a circuit closure event within a predetermined period, it is indicative of a situation involving a yarn end or other undesirable event that suggests that it would be potentially harmful to allow the CWM to continue operation without intervention. In such situation the CWM is made to shut down and a notification signal is sent. The signal may be sent to a monitor. In the case where there's opening of the circuit within the predetermined period, no notification would be sent, however, the CWM will be permitted to continue operation.

In this manner, the inbuilt intelligent module eliminates possibility of any faulty alarm generation for temporary loosening in yarn/tape (9), and more importantly the consequent shutting down of the CWM. Temporary slack of warp yarn/tape (9) is very common in weaving machines which on account of false alarms consumes significant amount of resources in terms of time and manpower utilization as machine get down for this time period, which is always desirable to avoid under any circumstances. It is evident from the foregoing discussion that the present invention has a number of embodiments.

1. A device for sensing end of warp yarn or tape on an fabric weaving loom, said device comprises a yarn-end detection means to detect the breakage of or end in said running yarn, an electric circuit of which said yarn detection means form a part, and a notification means to notify breakage of or end of yarn, characterised in that said yarn-end detection means comprising a first elemental having an electrically conducting outer surface said first element being fitted on a drop wire that has an opening for passage of said warp yarn, said drop wire being held in its normal operating position due to tension in said running yarn warp, and a pair of second elements each said second element having an electrically conducting inner surface, there being present a physical gap between said second elements, wherein, subsequent to the falling of said drop wire from its normal operating position due to substantial loss of tension in said warp, said electrical circuit/switch gets completed by said electrically conducting surfaces of first and second element coming in contact with each other, thereby triggering the notification means for a notification signal generation of yarn/tape break or end. A device as disclosed in embodiment 1, characterized in that said electrically conducting outer surface is spatially curved, and said internal surface carrying a dust-repelling geometrical shape.

A device as disclosed in embodiments 1 or 2, characterised in that said notification signal is an audio or a visual or audio-visual signal, or a signal indicating apparatus failure sent to a monitor.

A device as disclosed in embodiments 1 to 3, characterised in that said first element has a substantially conical outer surface.

A device as disclosed in any of embodiments 1 to 4, characterised in that said inner curved surface being provided with a shape corresponding to that of said outer surface of said first elements.

A device as disclosed in any of embodiments 1 to 5, characterised in that one detection means is provided for each of the running yarn that is being weaved on the weaving machine.

A device as disclosed in any of embodiment 1 to 6, characterised in that said apparatus is capable of detection of at least one broken yarn.

A as disclosed in any of embodiments 1 to 7, characterised in that said notification indicating yarn breakage identifies specific yarn which has broken.

A device disclosed in any of embodiments 1 to 8, characterised in that said notification is sent only in the event that said electric circuit remains closed for more than a predetermined time period. 10. A device disclosed in any of embodiments 1 to 9, characterised in that said predetermined period is in the range between 0.1 to 2 seconds.

11. A device disclosed in any of embodiments 1 to 10, characterised in that said the two second elements from any given pair of second elements are electrically connected at one end of respective second elements and at their other ends they are connected to a source of electric current.

12. A device disclosed in any of embodiments 1 to 11, characterised in that said inner curved surface has a number of sub- surfaces, and wherein the interfaces between said sub-surfaces being edges or points.

13. A device disclosed in any of embodiments 1 to 12, characterised in that said edges being sharp.

14. A method for sensing end of warp yarn (9) or tape on a circular weaving loom, characterized in that said method comprises the steps of

providing a device as disclosed in any one of embodiments 1 to 13, - detecting a yarn end,

- upon substantial loss of elevation of any drop wire (6), completing electrical circuit/switch,

sending a notification signal indicating detection of a yarn end or a yarn break,

- stopping the working of said circular weaving loom.

While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

Claims

Claims:

1. A device for sensing end of warp yarn (9) or tape on a fabric weaving loom, said device comprises a yarn-end detection means to detect the breakage of or end in said running yarn, an electric circuit of which said yarn detection means form a part, and a notification means to notify breakage of or end of yarn, characterised in that said yarn-end detection means comprising a first element (6B) having an electrically conducting outer surface (6C) said first element (6B) being fitted on a drop wire (6) that is provided corresponding to each individual yarn, said drop wire (6) has an opening (6A) for passage of said warp yarn (9), said drop wire (6) being held in its normal operating position due to tension in said running yarn warp, and a pair of second elements (7) provided corresponding to a group of said drop wires (6), each said second element (7) having an electrically conducting inner curved shaped surface (7B) corresponding to each said drop wire (6), there being present a physical gap (7 A) between said second elements (7), wherein, subsequent to the falling of said drop wire (6) from its normal operating position due to substantial loss of tension in said warp yarn (9), said electrical circuit/switch gets completed by said electrically conducting surfaces (6C and 7B) of first and second elements (6B and 7) coming in contact with each other, thereby triggering the notification means for a notification signal generation of yarn/tape break or end.

A device as claimed in claim 1, characterized in that said electrically conducting outer surface (6C) is spatially curved, and said inner curved shaped surface (7B) having a dust-repelling geometrical shape.

A device as claimed in claims 1 or 2, characterised in that said notification signal is an audio or a visual or audio-visual signal, or a signal indicating apparatus failure sent to a monitor.

A device as claimed in any of claims 1 to 3, characterised in that said outer surface (6C) is substantially conical.

A device as claimed in any of claims 1 to 4, characterised in that said inner curved shaped surface (7B) is provided with a shape corresponding to that of said outer surfaces (6C).

A device as claimed in any of claims 1 to 5, characterised in that one yarn- end detection means is provided for each of the running yarn (9) that is being weaved on the weaving machine.

A device as claimed in any of claims 1 to 6, characterised in that said device is capable of detection of at least one broken yarn.

A device as claimed in any of claims 1 to 7, characterised in that said notification indicating yarn breakage identifies specific yarn (9) which has broken.

A device as claimed in any of claims 1 to 8, characterised in that said notification is sent only in the event that said electric circuit remains closed for more than a predetermined time period.

10. A device as claimed in any of claims 1 to 9, characterised in that said predetermined period is in the range between 0.1 to 2 second.

11. A device as claimed in any of claims 1 to 10, characterised in that said the two second elements (7) from any given pair of second elements are electrically connected at one end of respective second elements and at their other ends they are connected to a source of electric current.

12. A device as claimed in any of claims 1 to 11, characterised in that said inner curved shaped surface (7B) has a number of sub-surfaces (7D), and wherein the interfaces between individual said sub-surfaces (7D) are edges or points.

13. A device as claimed in any of claims 1 to 12, characterised in that said edges being sharp.

providing a device as claimed in any one of claims 1 to 13, detecting a yarn end,

stopping the working of said circular weaving loom.