Apparatus and method for detecting signs of twisted yarn breakage

Abstract

To detect a breaking sign of traveling yarn in a garment manufacturing machine such as an embroidery machine or a sewing machine.SOLUTION: Whether or not fray or filament breakage occurs on a twisted yarn is detected by emitting laser beam in a cross direction with respect to a traveling direction of the twisted yarn traveling under tensile force along a straight line path, receiving the laser beam crossing the traveling twisted yarn by an optical sensor, and processing output of the optical sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a breakage sign detection device that detects signs of breakage in a running twisted yarn while applying tension. [Background technology]

[0002] Patent Document 1 describes a thread tension device for a sewing machine in which a CCD line sensor is provided in the upper thread path between the upper thread supply source and the stitch forming device, an LED is positioned opposite the CCD line sensor with the upper thread sandwiched between them, a charge amount signal from the CCD line sensor is processed to detect the thickness of the upper thread, and a thread clamping magnet that clamps and applies tension to the upper thread in the upper thread path between the upper thread supply source and the thread take-up lever is controlled according to the upper thread thickness information. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-39667 Summary of the Invention [Problem to be solved by the invention]

[0004] In sewing machines such as embroidery machines and sewing machines, threads can break (snip) during the sewing process. When threads break, it can cause defects in the product (product defects) and can also increase the sewing time required to rethread the product. In the invention of Patent Document 1, the tension can be adjusted depending on the thickness of the upper thread, but it is not possible to predict thread breakage.

[0005] The present invention aims to solve the problems of the prior art by providing a twist yarn breakage detection device that detects signs of twist yarn breakage while the twist yarn is running. Another object of the present invention is to provide a sewing machine that can detect signs of twist yarn breakage while the twist yarn is being supplied. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, according to the present invention, there is provided a twisted yarn breakage precursor detection device comprising: a laser light irradiation device that irradiates laser light in a direction transverse to the running direction of the twisted yarn running along a linear path under a predetermined tension; an optical sensor that receives the laser light that has crossed the running twisted yarn; and a processing device that processes the output of the optical sensor to detect fraying or filament breakage in the twisted yarn.

[0007] The present invention also provides a sewing machine including a needle bar drive mechanism that moves a needle bar up and down, a thread supply source that pays out a twisted thread, a thread tensioner that applies tension to the twisted thread, a thread take-up lever that moves up and down in synchronization with the up and down movement of the needle bar, and a thread take-up spring that is arranged between the thread tensioner and the take-up lever and around which the twisted thread is hooked and that flexes and deforms in response to the up and down movement of the take-up lever, the sewing machine further comprising: a laser light irradiation device that irradiates a laser light in a direction transverse to the traveling direction of the twisted thread traveling between the thread tensioner and the thread take-up spring; an optical sensor that receives the laser light that has crossed the traveling twisted thread; and a processing device that processes the output of the optical sensor to detect fraying or filament breakage in the twisted thread. [Effects of the Invention]

[0008] According to the present invention, fraying and broken filaments can be detected in a non-contact manner, and signs of twisted yarn breakage can be detected, thereby making it possible to prevent defective products from occurring. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a twisted yarn breakage precursor detection device according to a preferred embodiment of the present invention. [Figure 2] 2 is a partially enlarged view of the twisted yarn breakage sign detection device of FIG. 1, showing the optical sensor in the high axis direction from the laser light irradiation side. FIG. [Figure 3] 1, showing a twisted yarn breakage sign detection device according to another embodiment of the present invention. [Figure 4] 10 is a graph showing an example of a change over time in a voltage output from a photodiode. [Figure 5] 10 is a graph showing another example of the change over time in the voltage output from the photodiode. [Figure 6] 1 is a schematic diagram of a twisted yarn illustrating twisted yarn fraying and broken filaments as precursors to breakage. [Figure 7] 1 is a schematic perspective view of a thread supply device of an embroidery machine as an example of a sewing machine incorporating a twisted thread breakage sign detection device of the present invention; [Figure 8] 1 is a schematic perspective view of a thread supplying device of a sewing machine as an example of a sewing machine incorporating a twisted thread breakage sign detection device of the present invention. [Figure 9] 10 is a schematic diagram showing another example of an optical system of a twisted yarn breakage sign detection device. [Figure 10] 10 is a schematic diagram showing yet another example of an optical system of a twisted yarn breakage sign detection device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In FIG. 1, a twisted yarn S breakage sign detection device 10 (hereinafter simply referred to as breakage sign detection device) includes a laser light irradiation device 12, a photodiode 14 as an optical sensor, and a processing device 20 that processes the output of the photodiode 14.

[0011] The laser light irradiation device 12 may include a laser oscillator (not shown) that outputs laser light, a waveguide (not shown) that guides the laser light so that it is irradiated toward the twisted yarn S, and the like. The laser light irradiation device 12 irradiates the traveling twisted yarn S with laser light in a direction transverse to the traveling direction D of the twisted yarn S. A predetermined tension is applied to the twisted yarn S while it is traveling.

[0012] The photodiode 14 is disposed on the optical axis O of the laser light LB on the opposite side of the laser light irradiation device 12 with respect to the traveling twisted yarn S. The photodiode 14 is connected to a processing device 20. The processing device 20 processes the signal output from the photodiode 14 and determines whether or not there are any signs of breakage in the twisted yarn S.

[0013] The processing unit 20 may be configured with a computer and associated software, including a CPU (Central Processing Unit), memory devices such as RAM (Random Access Memory) and ROM (Read Only Memory), input / output ports, and a bidirectional bus interconnecting these. An alarm device 22 may be connected to the processing unit 20. The alarm device 22 may turn on a warning light (not shown) or emit an alarm sound such as a beep based on a signal or command from the processing unit 20.

[0014] A laser beam shaping element can be provided to shape the laser beam LB emitted from the laser beam emitting device 12. In the example of Figures 1 and 2, the laser beam shaping element includes a cylindrical lens 16 arranged between the laser beam emitting device 12 and the traveling path of the twisted yarn S, and a slit 18 arranged between the traveling path of the twisted yarn S and the photodiode 14.

[0015] The laser beam LB emitted from the laser beam irradiation device 12 is narrowed by the cylindrical lens 16 so that the dimension in the running direction D of the twisted yarn S gradually decreases toward the twisted yarn S, and is incident on the photodiode 14 at a predetermined dimension y. The laser beam LB is further narrowed by the slit 18 so that it is incident on the photodiode 14 at a predetermined dimension x in the width direction B, which is perpendicular to both the running direction D of the twisted yarn S and the optical axis O. In this way, when the twisted yarn S is not running, laser beams of a constant power from the laser beam irradiation device 12 are incident on the photodiode 14.

[0016] 1 and 2, the laser light shaping element uses a cylindrical lens 16 to narrow the laser light LB in the running direction D of the twisted yarn S, but the present invention is not limited to this, and as shown in Fig. 3, the laser light LB may be expanded in the Y direction parallel to the running path of the twisted yarn S. In Fig. 3, the same components as those in Figs. 1 and 2 are designated by the same reference numerals, and redundant explanations will be omitted below.

[0017] In the embodiment shown in FIG. 3, the breakage sign detection device 30 includes a laser light shaping element consisting of two lenses 32, 34 disposed between the laser light irradiator 12 and the device path of the twisted yarn S. The two lenses 32, 34 are disposed closer to the laser light treatment device 20 than the path of the twisted yarn S. The lenses 32, 34 act as beam expanders that expand the laser light LB in the Y direction parallel to the path of the twisted yarn S. A slit 36 ​​is disposed between the path of the twisted yarn S and the photodiode 14. Unlike the slit 18, the slit 36 ​​focuses the laser light LB incident on the photodiode 14 in a direction parallel to the path of the twisted yarn S. The slit 36 ​​may be configured similarly to the slit 18.

[0018] The laser light LB is expanded in the Y direction by the lenses 32 and 34, which are beam expanders, and irradiates the running twisted yarn S over a predetermined length LS in the Y direction. More specifically, the laser light LB is expanded in the Y direction by the lens 32 located on the laser light processing device 20 side, and is converged toward the photodiode 14 by the lens 34 located on the photodiode 14 side. In this way, the signal output from the photodiode 14 becomes equivalent to the output signal from the photodiode 14 in the breakage sign detection device 10 of Figures 1 and 2 averaged over the predetermined length LS. The predetermined length LS over which the twisted yarn S is irradiated is referred to as the inspection length LS.

[0019] In the present invention, the laser light shaping element of the fracture sign detection device is not limited to that shown in Figures 1 to 3. As an example, further modified examples of fracture sign detection are shown in Figures 9 and 10. In Figures 9 and 10, the same components as those in Figures 1 and 2 are given the same reference numerals, and redundant explanations will be omitted below. Furthermore, although the processing device 20 and alarm device 22 are also omitted in Figures 9 and 10, the embodiment of Figures 9 and 10 can also be provided with a similar processing device and alarm device.

[0020] In the embodiment shown in FIG. 9, a breakage sign detection device 60 has a laser light shaping element consisting of three lenses 62, 64, and 66 disposed between the laser light emitting device 12 and the device path of the twisted yarn S. Two of the lenses 62, 64 are disposed closer to the laser light processing device 20 than the path of the twisted yarn S, and one lens 66 is disposed closer to the photodiode 14 than the path of the twisted yarn S. A slit 68 is disposed between the lens 66 and the photodiode 14. The slit 68 has a similar structure to the slit 18.

[0021] The lens 62 expands the laser light LB in the Y direction parallel to the travel path of the twisted yarn S, the lens 64 converts the expanded laser light into parallel rays perpendicular to the travel path of the twisted yarn S, and the lens 66 converges the parallel laser light toward the photodiode 14.

[0022] In this way, the laser light LB emitted from the laser light processing device 20 is expanded in the Y direction by the lenses 62 and 64, which act as beam expanders, and after irradiating the running twisted yarn S over the inspection length LS, is converged by the lens 66 toward the photodiode 14. In this embodiment, too, the signal output from the photodiode 14 is equivalent to the output signal from the photodiode 14 in the breakage sign detection device 10 of Figures 1 and 2 averaged over the inspection length LS. However, in this embodiment, the laser light LB is made into a parallel beam by the lens 64, so the inspection length LS can be determined or made constant more stably than in the embodiment of Figure 3.

[0023] In the embodiment shown in FIG. 10 , a breakage sign detection device 70 has a laser light shaping element consisting of two lenses 72, 74, and 66 disposed between the laser light emitting device 12 and the device path of the twisted yarn S. The lens 72 is disposed closer to the laser light processing device 20 than the path of the twisted yarn S, and the lens 74 is disposed closer to the photodiode 14 than the path of the twisted yarn S. A slit 76 is disposed between the lens 74 and the photodiode 14. The slit 76 has a similar configuration to the slit 18.

[0024] The lens 72 expands the laser light LB in the Y direction parallel to the travel path of the twisted yarn S, and the lens 74 converges the expanded laser light toward the photodiode 14. In this way, the laser light LB emitted from the laser light processing device 20 is expanded in the Y direction by the lens 72 and irradiates the traveling twisted yarn S over the inspection length LS, and then is converged by the lens 74 toward the photodiode 14. In this embodiment, the signal output from the photodiode 14 is also equivalent to the output signal from the photodiode 14 in the breakage sign detection device 10 of FIGS. 1 and 2 averaged over the inspection length LS. However, in this embodiment, the laser light LB irradiates the twisted yarn S before the lens 74 converges the laser light LB on the photodiode 14, making it possible to determine or keep the inspection length LS more stably than in the embodiment of FIG. 3.

[0025] 4 and 5 show examples of the output from the photodiode 14. The graphs in Figures 4 and 5 show the change over time in the voltage output from the photodiode 14, with the vertical axis representing voltage (V) and the horizontal axis representing time (s). In Figures 4 and 5, the voltage output from the photodiode 14 typically changes in a relatively short period of about several tens of milliseconds, and with a small amplitude (voltage width) of about 1 / 100 to 1 / 10 volt.

[0026] However, the output voltage from the photodiode 14 may sometimes fluctuate irregularly, for example, during the time period indicated by Δt in FIG. 4, or during the time periods indicated by Δt1 and Δt2 in FIG.

[0027] Referring to Figure 6, a twisted yarn S1 with fraying or broken filaments, which are signs of breakage, is shown in comparison with a normal twisted yarn S2. As a result of repeated experiments, the inventors discovered that voltage fluctuations such as Δt, Δt1, and Δt2 in Figure 4 correspond to the parts of twisted yarn S1 with fraying or broken filaments, as shown in (a) and (b) in Figure 6, and that twisted yarns with such fraying or broken filaments are more susceptible to yarn breakage or breakage.

[0028] In other words, before the twisted yarn breaks or is torn, it will fray or the filaments that make up the twisted yarn will break. The processing device 20 processes the voltage value output from the photodiode 14 and detects such fraying or filament breakage as a sign that the twisted yarn S is about to break. As an example, a voltage value fluctuation of a predetermined voltage range, for example, several hundred millivolts, at a predetermined frequency, for example, several tens of millihertz, continuing for a predetermined time, for example, one second or more, can be considered a sign that the twisted yarn S is about to break. Such judgment criteria can be determined in advance through experiments or the like and stored in the memory device of the processing device 20.

[0029] The breakage precursor detection devices 10, 30 can be incorporated into sewing machines such as embroidery machines (FIG. 7) and sewing machines (FIG. 8). FIG. 7 is a perspective view showing an example of a thread supply device for an embroidery machine. As is commonly known in the field of sewing machines, the thread supply device includes multiple thread tension regulators 40, multiple thread take-up levers 42, multiple thread take-up springs 44, and multiple needle bars 46. The thread take-up springs 44 are arranged on the travel paths of multiple twisted threads (not shown), between the corresponding thread tension regulators 40 and the corresponding thread take-up levers 42. In the example shown in FIG. 7, a thread breakage detection device 48 that detects a breakage of the twisted thread is arranged between the thread tension regulators 40 and the thread take-up springs 44.

[0030] Each of the multiple twisted yarns is unwound from a thread supply source such as a bobbin (not shown), passes through the thread tension regulator 40, the thread take-up spring 44, and the thread take-up lever 42, and is threaded through the eye of a corresponding needle bar 46 (not shown). The thread supply device may have the breakage warning detector 10 or 30 disposed between the thread tension regulator 40 and the thread take-up spring 44. That is, the thread supply device may be configured to irradiate the twisted yarn (not shown) running between the thread tension regulator 40 and the thread take-up spring 44 with a laser beam in a transverse direction. As in the example of FIG. 7 , if a thread breakage detector 48 is provided, the breakage warning detector 10 or 30 may be disposed between the thread breakage detector 48 and the thread take-up spring 44.

[0031] FIG. 8 is a perspective view showing an example of a thread supply device for a sewing machine. As is commonly known in the field of sewing machines, the thread supply device includes a thread tension regulator 50, a thread take-up lever 52, a thread take-up spring 54, and a needle bar 56. The thread take-up spring 54 is located between the thread tension regulator 50 and the thread take-up lever 52 along the path of the twisted thread S. The twisted thread S is unwound from a thread supply source such as a bobbin (not shown), passes through the thread tension regulator 50, the thread take-up spring 54, and the thread take-up lever 52, and is threaded through the eye of the needle bar 56 (not shown). The thread supply device can include the breakage warning detector 10 or 30 described above between the thread tension regulator 50 and the thread take-up spring 54. In other words, a laser beam can be irradiated in a transverse direction onto the portion of the twisted thread S, indicated by A, that runs between the thread tension regulator 50 and the thread take-up spring 54.

[0032] In this way, by incorporating the breakage precursor detection device 10 or 30 into a sewing machine such as an embroidery machine or a sewing machine and detecting fraying or filament breakage, it is possible to detect precursors to thread breakage and reduce product defects. One embodiment of the present invention is described below. A sewing machine including a needle bar drive mechanism that moves a needle bar up and down, a thread supply source that pays out a twisted thread, a thread tensioner that applies tension to the twisted thread, a thread take-up lever that moves up and down in synchronization with the needle bar that moves up and down, and a thread take-up spring that is disposed between the thread tensioner and the thread take-up lever, around which the twisted thread is hooked and that flexes and deforms in accordance with the up and down movement of the thread take-up lever, a laser light irradiation device that irradiates a laser light along an optical axis that extends in a direction transverse to the running direction of the twisted yarn running between the yarn tensioner and the yarn take-up spring; a beam expander disposed between the laser light irradiator and the traveling path of the twisted yarn, for expanding the laser light in a direction parallel to the traveling path of the twisted yarn; a slit disposed between the traveling path of the twisted yarn and the optical sensor, for narrowing the laser light that crosses the traveling twisted yarn and enters the optical sensor to a predetermined dimension in a width direction perpendicular to both the traveling direction of the twisted yarn and the optical axis; an optical sensor that is disposed on the optical axis of the laser light on the opposite side of the laser light emitting device with respect to the traveling twisted yarn and that receives the laser light that has crossed the traveling twisted yarn; and a processing device that processes the output of the optical sensor to detect fraying or broken filaments in the twisted yarn. [Explanation of symbols]

[0033] 10. Fracture precursor detection device 12 Laser light irradiation device 14 Photodiode 16 Cylindrical Lens 18 Slit 20 Processing equipment 22 Alarm device 30 Breakage precursor detection device 32 Lens 34 Lens 36 Slit 40 Thread tension 42 Balance 46 Needle Bar 48 Detection Device 50 Thread tension 52 Balance 56 Needle bar

Claims

[Claim 1] In a twisted yarn breakage precursor detection device, a laser light irradiation device that irradiates a laser light along an optical axis extending in a direction transverse to the running direction of the twisted yarn running along a linear path under a predetermined tension; an optical sensor that is disposed on the optical axis of the laser light on the opposite side of the laser light emitting device with respect to the traveling twisted yarn and that receives the laser light that has crossed the traveling twisted yarn; a beam expander disposed between the laser light irradiator and the traveling path of the twisted yarn, and configured to expand the laser light in a direction parallel to the traveling path of the twisted yarn; a slit disposed between the traveling path of the twisted yarn and the optical sensor, for narrowing the laser light that crosses the traveling twisted yarn and enters the optical sensor to a predetermined dimension in a width direction perpendicular to both the traveling direction of the twisted yarn and the optical axis; an optical sensor that is disposed on the optical axis of the laser light on the opposite side of the laser light emitting device with respect to the traveling twisted yarn and that receives the laser light that has crossed the traveling twisted yarn; and a processing device that processes the output of the optical sensor to detect fraying or broken filaments in the twisted yarn.

Images