A twisting unit of yarn consisting of at least two twisted threads

Abstract

A twisting unit for a yarn consisting of at least two twisted threads. The twisting unit includes a conductor with at least one pigtail guide (12) in which the yarn (8) is twisted in a longitudinal direction (X-X); a cutting device for the yarn (8) configured to cut the yarn (8) upon detection of a breakage in at least one of the threads forming the yarn (8); at least one detection device (16) for detecting a breakage in at least one of the threads forming the yarn (8), including a tension sensor (20) of the yarn (8); and a processing and control unit (24) operatively connected to the tension sensor (20) of the yarn (8). The twisting unit according to this application is capable of independently managing the detection of thread breakage, stopping twisting, and the subsequent recovery of the twisting process itself.

Description

Technical Field

[0001] This utility model relates to a twisting unit with an independent wire breakage control sensor and a method for detecting wire breakage. Background Technology

[0002] As is well known, in twisting machines, especially double-tank twisting machines, two or more strands of yarn are joined and combined by applying mutual twist in order to obtain yarns with excellent technical characteristics, especially greater strength and regularity.

[0003] The twisted yarn leaving the spindle passes through a guide ring, commonly known as a pigtail, which carries the twisted yarn toward an upper collection area where it is wound onto a tube to form a spool.

[0004] The pigtail guide plays a crucial role in the path of the guide line and in adjusting the height of the air ring to incorporate tension and change its shape.

[0005] Sometimes, during the unwinding process, one or more strands forming the twisted yarn break unexpectedly, and without a dedicated system for detecting the breakage, the winding into the spool continues uninterrupted, supplying the remaining yarn, while the broken strands begin to accumulate and tangle, making it particularly difficult to restore the head's function.

[0006] In this regard, electronic systems are used to continuously monitor the tension of the twisted yarn, which represents a quantitative parameter that best indicates its goodness and regularity.

[0007] This is due to the fact that the possible breakage of one of the strands forming the twisted yarn causes a change in the resistance cross section, which immediately indicates a fluctuation in the tension of the yarn itself.

[0008] For example, known systems designed to solve these problems envision constantly measuring the pressure exerted by the line in a direction transverse to its travel, which is directly related to its tension.

[0009] For example, known techniques include the use of piezoelectric sensors, which are typically mounted directly near the pigtail guide and have an open fork made of ceramic material that receives pressure in the lateral direction from a longitudinally extending line.

[0010] Since the contact pressure is proportional to the tension of the twisted and wound yarn, the tension change caused by the breakage alters the pressure and thus the voltage of the output signal.

[0011] Typically, the control unit processes the sensor output to infer information about the average yarn tension and the rotational speed of the air bladder, starting from the amplitude and frequency of the signal, respectively.

[0012] Systems based on existing technology are not without their flaws and defects.

[0013] For example, patent EP0616058B1 describes a piezoelectric system for yarn quality control, in which average tension and speed values ​​derived from processing the output signal of a piezoelectric sensor are compared with a reference threshold by a dedicated comparator, which must be manually entered by an operator in a machine PC.

[0014] Therefore, these values ​​must be known in advance based on the characteristics of the yarn to be processed, which in turn undergoes changes with each batch change, thereby impairing the machine's operational versatility.

[0015] Patent IT1239766B also discloses a piezoelectric device for monitoring line tension, wherein the response of the pressure sensor is highly dependent on its mounting location, as the contact pressure increases with the deviation applied to the line relative to its nominal path.

[0016] Therefore, in existing devices, the installation location of the sensor becomes highly relevant and must be rationally selected in advance based on the expected tension of the wire. Utility Model Content

[0017] Therefore, it was felt that there was a need to address the shortcomings and limitations mentioned in existing technologies.

[0018] This need is met by the winding unit and detection method according to this utility model.

[0019] According to this application, a twisting unit for a yarn consisting of at least two twisted threads is provided, the twisting unit comprising: - a guide wire with at least one pigtail guide, the yarn being twisted in the longitudinal direction within the guide wire; - a yarn cutting device configured to cut the yarn upon detection of a breakage in at least one thread forming the yarn; - at least one detection device for detecting a breakage in at least one of the threads forming the yarn, the at least one detection device including a tension sensor for the yarn; - a processing and control unit operatively connected to the tension sensor for the yarn, wherein the tension sensor includes a fork element in which the yarn flows, the fork element having two teeth substantially perpendicular to the longitudinal direction; and wherein the processing and control unit is configured to use the tension sensor as a presence sensor for the yarn.

[0020] Furthermore, the tension sensor is piezoelectric.

[0021] Furthermore, the tension sensor is of either absolute or relative type.

[0022] Furthermore, the tension sensor measures the tension applied by the yarn to at least one of the teeth in a transverse direction substantially perpendicular to the longitudinal direction.

[0023] According to this application, a method for detecting the breakage of at least one twisted yarn forming a yarn in a twisting unit is also provided, comprising the steps of: - performing a self-learning step when starting and / or resuming the twisting process, wherein in the self-learning step, a reference value of the yarn tension is stored for monitoring the reference value during twisting; - interrupting the twisting if, during twisting, the yarn tension experiences a percentage decrease relative to the reference value that is greater than or equal to a predetermined maximum percentage deviation.

[0024] Further, the method includes the following steps: storing the reference value when the frequency of the reference value of the yarn tension has stabilized.

[0025] Furthermore, the reference value is stored when the tension of the yarn stabilizes at a frequency within the maximum oscillation range of less than 4 Hz.

[0026] Further, it includes the following step: storing the reference value of the yarn tension when the twisting spindle reaches the state rotation speed.

[0027] Further, it includes the following step: directly measuring the reference value of the tension of the yarn.

[0028] Further, the method includes the following steps: indirectly measuring the reference value of the yarn tension by measuring a signal proportional to the tension of the yarn to be monitored.

[0029] Furthermore, the predetermined maximum percentage deviation is between 5% and 30%.

[0030] Furthermore, the processing and control unit is configured to use the tension sensor as a line presence sensor.

[0031] Furthermore, the processing and control unit is configured to control the yarn cutting device when at least one break is detected.

[0032] The twisting unit and method according to this application can independently manage the detection of thread breakage, the cessation of twisting, and the recovery of subsequent twisting itself. Attached Figure Description

[0033] Further features and advantages of the present invention will become more clearly understood from the following description of preferred and non-limiting embodiments, as illustrated in the accompanying drawings:

[0034] Figure 1A perspective view of a twisting machine including multiple twisting units according to the present invention is depicted;

[0035] Figures 2 to 3 Described from above and below respectively Figure 1 Detail II perspective view;

[0036] Figure 4 A flowchart illustrating the operation of the twisting unit according to an embodiment of the present invention is provided.

[0037] Elements or parts thereof that are used in the embodiments described below will be indicated using the same reference numerals. Detailed Implementation

[0038] Referring to the above figure, the number 4 generally indicates the twisting unit of the yarn 8, which consists of at least two twisted threads.

[0039] The twisting unit 4 includes a conductor for at least one pigtail guide 12, in which the yarn 8 is twisted in the longitudinal direction XX; and a yarn cutting device (not depicted) configured to cut the yarn if at least one of the yarns forming the yarn 8 is detected to be broken.

[0040] The twisting unit 4 also includes at least one detection device 16 for detecting the breakage of at least one of the yarns forming the yarn 8, the at least one detection device including a tension sensor 20 of the yarn 8.

[0041] As better described below, the tension sensor 20 of the yarn 8 is configured to measure the tension experienced by the yarn 8 directly or indirectly.

[0042] The tension sensor 20 of the yarn 8 includes a processing and control unit 24 operatively connected to the tension sensor 20 itself of the yarn 8.

[0043] According to one possible implementation, the tension sensor 20 is piezoelectric.

[0044] The tension sensor 20 can be of the absolute type, in which the output signal is proportional to the input signal, or of the relative type, in which the output is typically not proportional to the input.

[0045] According to one possible implementation, the tension sensor 20 includes a fork element 28 in which yarn 8 flows, the fork element 28 having two teeth 32 that are substantially perpendicular to the longitudinal direction XX.

[0046] The tension sensor 20 is configured to measure the tension applied by the yarn in a transverse direction YY, substantially perpendicular to the longitudinal direction XX, to at least one of the teeth 32. This tension in the transverse direction YY is, in turn, a function of the longitudinal tension or traction force of the yarn 8. In this case, it is an indirect measurement of the traction force of the yarn 8.

[0047] Advantageously, the processing and control unit 24 is configured such that:

[0048] When starting and / or resuming the twisting process, a self-learning step is performed, in which a reference value R for the tension of yarn 8 is stored for monitoring during twisting.

[0049] If, during twisting, the tension of yarn 8 experiences a decrease of a percentage relative to the reference value R that is greater than or equal to a predetermined maximum percentage deviation, then twisting is stopped.

[0050] Typically, the processing and control unit 24 is configured to control the cutting device of the yarn 8 when a breakage is detected: in other words, after a breakage is detected, the yarn 8 is cut and the twisting step is restarted.

[0051] Preferably, the reference value R is stored when the tension of the yarn 8 is stable at a frequency within the maximum oscillation range of less than 4 Hz.

[0052] For example, when the twisting spindle reaches the state rotation speed and therefore the frequency of its signal has stabilized, the reference value R of the tension of the stored yarn 8.

[0053] According to one possible implementation, the reference value R of the tension of yarn 8 is a direct measurement of the tension of yarn 8.

[0054] It is also conceivable that the reference value R of the tension of yarn 8 is an indirect measurement of the tension, which is proportional to the tension of the yarn 8 to be monitored.

[0055] Preferably, the predetermined maximum percentage difference is between 5% and 30%, depending on the total twist applied to the yarn 8 and the type and number of twists of each yarn forming the twisted yarn 8.

[0056] The value of this predetermined maximum percentage difference may depend on the operating conditions of the twisting unit 4 and / or the type of yarn 8 used; the type may further include the yarn material, its name, and the number of threads forming the yarn and the type of twisting the threads undergo.

[0057] The processing and control unit 24 can also be configured to use the tension sensor 20 as a yarn presence sensor. This eliminates the need for an additional yarn presence sensor.

[0058] The function of the twisting unit according to this invention will now be described.

[0059] In particular ( Figure 4 When the twisting unit is started, the tension sensor 20 is initialized.

[0060] Then a preliminary check for the presence of yarn 8 is performed, for which:

[0061] If yarn 8 does not exist, then the command is to cut;

[0062] If yarn 8 is present, proceed to the next step.

[0063] Therefore, a standard yarn presence check is performed, so that signal frequency stability monitoring begins when yarn 8 is present:

[0064] If the frequency is not stable, cut the yarn 8;

[0065] If the frequency is stable, proceed to the next step.

[0066] In the next step, signal gain adjustment begins:

[0067] If the gain cannot be adjusted, cut yarn 8;

[0068] If the gain has already been adjusted, proceed to the next step.

[0069] In this additional step, monitoring begins to detect the breakage of at least one strand that forms the twisted yarn.

[0070] When a breakage occurs, the tension sensor detects that the tension of yarn 8 has decreased; in particular, if this percentage decrease relative to the reference value R is greater than or equal to a maximum predetermined percentage deviation, twisting is interrupted.

[0071] Then cut yarn 8 and return to the normal presence control step of yarn 8, and repeat the loop just described when the presence of yarn 8 is detected again.

[0072] As can be understood from the description, the present invention has significant advantages over current solutions of the prior art and makes it possible to overcome their disadvantages.

[0073] First, thanks to the use of adaptive sensors, operators no longer need to worry about manually inputting any reference value for line tension into the PC as a function of a specific fiber or name, or the linear speed of yarn collection.

[0074] The unit is preferably able to set itself up at startup or restart and independently manage the detection of thread breakage, the cessation of twisting, and the subsequent recovery of twisting itself.

[0075] In addition, the tension sensor configured in this way can also be used as a wire presence sensor, which helps to simplify the mechanical and electronic architecture of the twisting unit and thus reduce the size of the twisting unit.

[0076] Furthermore, when using a piezoelectric voltage sensor, once the self-learning process has been performed, the installation position of the tension sensor itself becomes irrelevant because what is being monitored is the relative (rather than absolute) deviation or offset of the tension signal, and it is not necessary to make the detected value consistent with the set point set by the previous adjustment of the tension sensor itself (as is the case in prior art solutions).

[0077] Those skilled in the art can make various modifications and changes to the above solution to meet possible and specific requirements.

[0078] The scope of protection of this utility model is defined by the appended claims.

Claims

1. A twisting unit (4) for a yarn (8) consisting of at least two twisted threads, the twisting unit comprising: - A guide wire of at least one pigtail guide (12), wherein the yarn (8) is twisted in the guide wire along the longitudinal direction (XX). - The yarn (8) cutting device is configured to cut the yarn (8) upon detecting that at least one thread forming the yarn (8) has broken. - At least one detection device (16) for detecting the breakage of at least one of the threads forming the yarn (8), the at least one detection device including a tension sensor (20) of the yarn (8), - A processing and control unit (24) is operatively connected to the tension sensor (20) of the yarn (8). The tension sensor (20) is characterized in that it includes a fork element (28) in which the yarn (8) flows, the fork element (28) having two teeth (32) substantially perpendicular to the longitudinal direction (XX); and The processing and control unit (24) is configured to use the tension sensor (20) as a presence sensor for the yarn (8).

2. The twisting unit (4) according to claim 1, characterized in that, The tension sensor (20) is piezoelectric.

3. The twisting unit (4) according to claim 1 or 2, characterized in that, The tension sensor (20) is of absolute or relative type.

4. The twisting unit (4) according to claim 1, characterized in that, The tension sensor (20) measures the tension applied by the yarn (8) to at least one of the teeth (32) in a transverse direction (YY) substantially perpendicular to the longitudinal direction (XX).

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