Yarn break detector of a spinning machine

Abstract

 A spinning machine has a ring plate, a ring fixed on the ring plate and a traveler slidably mounted on the ring. The traveler is made of a magnetic material. A yarn break detector of the spinning machine detects the traveler to determine presence or absence of a yarn break. The yarn break detector is characterized in that the yarn break detector includes a magnet and a magnetometer that are located on or above the ring plate. The magnet magnetizes the traveler. The magnetometer uses a magneto-impedance element to detect magnetism of the magnetized traveler.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to a yarn break detector of a spinning machine and more particularly to a yarn break detector that detects a moving traveler thereby to determine the presence or absence of a yarn break in a spinning machine having a ring such as a ring spinning machine, a ring twisting machine or the like.

[0002] Contact-type and noncontact-type yarn break detectors of a spinning machine have been known in the art. The contact-type yarn break detector has a lever that is in contact with a yarn being spun to detect the presence or absence of a yarn break. When the contact-type yarn break detector is used for a long time, the support device of the lever is worn due to the vibration of the lever. In addition, cotton fly and any other dust are attached to the support device thereby to reduce the detection sensitivity of the contact-type yarn break detector. In order to solve such problems, the noncontact-type yarn break detector is proposed and used.

[0003] A noncontact-type yarn break detector is disclosed by Japanese Unexamined Patent Application Publication No. 50-123940. The detector includes a permanent magnet and an electromagnetic impulse detector. The permanent magnet is fixed on the ring support of the spinning machine and the electromagnetic impulse detector is fixed on the ring support in proximity to the passageway of the traveler at least part of which is made of a ferromagnetic material. In the yarn break detector of the Publication No. 50-123940, the traveler slightly magnetized by the permanent magnet induces dynamic pulse voltage in the coil of the electromagnetic impulse detector.

[0004] Another noncontact-type yarn break detector is disclosed by Japanese Unexamined Patent Application Publication No. 2010-111982. This detector includes a sensor portion that detects a magnetic traveler sliding on the magnetic ring fixed on the ring plate (or a ring rail) by electromagnetic induction produced when the traveler crosses the magnetic circuit.

[0005] In each of the yarn break detectors of the Publications No. 50-123940 and No. 2010-111982 both of which have electromagnetic induction type sensors, the distance which the sensor (or the sensor portion) can detect the traveler is relatively small because of the small effect of the traveler on the magnetic circuit. The sensor needs to be located in proximity to the ring on which the traveler slides. If the sensor is located in proximity to the ring, however, the sensor may interfere with yarn piecing operation. In addition, if the sensor is located in proximity to the ring, connection of the sensor to a device that processes detection signals of the sensor and determines the presence or absence of a yarn break becomes complicated and hence costly. In the ring spinning machine, a plurality of rings having different diameters may be prepared and a ring that has a diametric size meeting the specific spinning condition is selected to be used. In this case, each time the ring is changed with a ring having a different diameter, the position of the sensor needs to be changed accordingly, with the result that the ring changing becomes troublesome and time-consuming.

[0006] The present invention is directed to providing a yarn break detector of a spinning machine, which allows the sensor to be mounted at a position where the need of changing of the mounting position of the sensor due to a change of the ring diameter is eliminated and no interference occurs between the sensor and yarn piecing operation.

SUMMARY OF THE INVENTION

[0007] In accordance with an aspect of the present invention, there is provided a yarn break detector of a spinning machine. The spinning machine has a ring plate, a ring fixed on the ring plate and a traveler slidably mounted on the ring. The traveler is made of a magnetic material. The yarn break detector detects the traveler to determine presence or absence of a yarn break. The yarn break detector is characterized in that the yarn break detector includes a magnet and a magnetometer that are located on or above the ring plate. The magnet magnetizes the traveler. The magnetometer uses a magneto-impedance element to detect magnetism of the magnetized traveler.

[0008] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

Fig. 1A is a fragmentary schematic plan view showing an arrangement of rings and yarn break detectors of a spinning machine according to an embodiment of the present invention;

Fig. 1B is an enlarged schematic plan view showing cops whose yarns are being spun, travelers and the yarn break detectors of the spinning machine of Fig. 1A;

Fig. 2 is a schematic sectional view showing the relation among the cop, the traveler and a magnet of the yarn break detector of Fig. 1 B;

Fig. 3 is a schematic perspective view showing the relation among the traveler, the magnet and a magnetometer of the yarn break detector of Fig. 2;

Fig. 4A is a graph showing the variation with time of the output of the magnetometer of Fig. 3 in the presence of the magnet of Fig. 3;

Fig. 4B is a graph showing the variation with time of the output of the magnetometer of Fig. 3 in the absence of the magnet of Fig. 3;

Fig. 5 is a schematic plan view showing a yarn break detector of a spinning machine according to a modification of the embodiment of the present invention;

Fig. 6 is a schematic plan view showing the relation among a cop whose yarn is being spun, a traveler and a magnet of a yarn break detector of a spinning machine according to another modification of the embodiment of the present invention; and

Fig. 7 is a schematic sectional view showing the relation among the cop, the traveler and the magnet of the yarn break detector of the spinning machine of Fig. 6.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0010] The following will describe the yarn break detector of the spinning machine as applied to a ring spinning machine according to the embodiment of the present invention with reference to Figs. 1A through 4B. Referring to Fig. 1A showing the ring spinning machine in its fragmentary schematic plan view, it includes a ring plate 11 and a plurality of rings 12 that are fixed on the ring plate 11 at a regular interval. Referring to Fig. 1B, the ring spinning machine further includes a plurality of travelers 13 made of magnetic materials. The travelers 13 are mounted on the rings 12 so as to be slidable along flanges 12A of the rings 12, respectively.

[0011] The yarn break detector is configured to detect the traveler 13 sliding on the ring 12 fixed on the ring plate 11 to determine the presence or absence of a yarn break. As shown in Fig. 1B, the yarn break detector for each ring 12 includes a permanent magnet 14 and a magnetometer 15 that are located on or above the ring plate 11. The permanent magnet 14 serves as the magnet of the present invention and is adapted to magnetize the traveler 13. The magnetometer 15 uses a magneto-impedance element to detect magnetism of the magnetized traveler 13.

[0012] In a spinning mill, only the diameters of the rings may be changed at the same ring plate in changing of the spinning condition. In the yarn break detector of the present embodiment, the magnetometer 15 is located at a position that is free from interference with the traveler 13 sliding on a ring 12 fixed on the ring plate 11 and having the greatest diameter. The magnetometer 15 has a sensor portion that is directed to face the center of the ring 12.

[0013] A traveler clearer 16 is fixed on the ring plate 11 for each ring 12 to remove fibers such as cotton flies attached to the traveler 13. The traveler clearer 16 has a clearing member 16A that scratches off the fiber attached to the traveler 13. The position of the traveler clearer 16 to be fixed on the ring plate 11 is accurately adjustable so that the tip end of the clearing member 16A and the travel region of the traveler 13 form therebetween a clearance of a predetermined value. More specifically, the traveler clearer 16 has therethrough an elongated hole 16B extending in a radial direction of the ring 12 and a screw 17 is inserted through the elongated hole 16B and threaded in a threaded hole formed in the ring plate 11. In the present embodiment, the aforementioned permanent magnet 14 is formed integrally with the traveler clearer 16. The permanent magnet 14 is fixed to the traveler clearer 16 by adhesive so that the magnetization of the permanent magnet 14 is directed in a radial direction of the ring 12 and the magnetic pole of the permanent magnet 14 is opposed to the ring 12.

[0014] As shown in Fig. 1A, a control board 18 is located in front of the ring plate 11 (or on the lower side of the ring plate 11 as seen in Fig. 1A) and has a CPU (not shown) that processes the detection signal of each magnetometer 15 to determine the presence or absence of a yarn break. The control board 18 is supported by the ring plate 11 via a support 19. In the present embodiment, the plurality of rings 12 are fixed on one ring plate 11 and the magnetometers 15 are located diagonally behind the respective rings 12.

[0015] Generally, the ring spinning machine includes several hundreds of spindles or spinning stations, or more and a plurality of ring plates 11 are located along the width direction of the machine so that the rings 12 are arranged at a regular spaced interval. For example, in the structure wherein the ring spinning machine has on one side thereof four hundreds eighty spindles and twenty four rings 12 are fixed on one ring plate 11, twenty ring plates 11 are located on one side of the ring spinning machine. The CPU of each ring plate 11 is connected to a master controller 20 via a wire (not shown) so as to transmit a signal that is indicative of the processing result of the detection signal of the magnetometer 15 to the master controller 20 via serial communication.

[0016] The following will describe the operation of the above-described yarn break detector. The permanent magnet 14 fixed to each traveler clearer 16 is held so that the magnetic flux is generated in the radial direction of the ring 12. When a cop 30 is rotated in accordance with the rotation of the spindle (not shown) during the spinning operation of the ring spinning machine, except for yarn break, the traveler 13 engaging with the yarn Y slides on the flange 12A of the ring 12 at a speed corresponding to the speed of the cop 30 as shown in Fig. 2. As schematically shown in Fig. 3, each time the traveler 13 makes a circuit of the ring 12, the traveler 13 crosses the magnetic flux once that flows from the magnetic pole of the permanent magnet 14 toward the ring 12, so that the traveler 13 is magnetized. In the present embodiment wherein the traveler 13 is magnetized by the permanent magnet 14 again even if the traveler 13 is temporarily demagnetized by any disturbance, the traveler 13 is detectable by the magnetometer 15 despite any demagnetization of the traveler 13.

[0017] When the traveler 13 passes through the detectable region of the magnetometer 15 while making a circuit of the ring 12, the magnetometer 15 detects the magnetized traveler 13. The detection signals of the magnetometers 15 are transmitted and the CPU of the control board 18 receives the output signals successively from the magnetometers 15. The CPU determines that normal spinning operation is being performed when the CPU receives a pulse voltage and also determines that there is the presence of a yarn break when the CPU fails to receive any pulse voltage. The CPU transmits to the master controller 20 a signal that is indicative of the presence of any spindle whose yarn is broken and of identification of such spindle (or a spindle number) based on the command signal from the master controller 20. Thus, the master controller 20 determines the spinning state of each spindle based on the output signal of the CPU.

[0018] The magnetometer 15 uses a magneto-impedance element that has a coil and an amorphous wire. The magneto-impedance element makes use of the MI (magneto-impedance) effect according to which the impedance of the amorphous wire is changed with fluctuation of the external magnetic field, so that the magnetometer 15 has a high sensitivity.

[0019] In the background art which uses the electromagnetic induction type sensor, the detectable distance between such sensor and the traveler 13 (or the ring 12) is about 3 mm. On the other hand, the detectable distance between the magnetometer 15 and the traveler 13 (or the ring 12) when the magnetometer 15 of the present embodiment detects the magnetized traveler 13 is about 5 mm in the absence of the permanent magnet 14, and the detectable distance is about 20 mm in the presence of the permanent magnet 14.

[0020] The rings 12 may be formed with different diameters ranging between 36 mm and 51 mm, and the difference of the rings 12 in radius is 7.5 mm at a maximum. In the presence of the permanent magnet 14, therefore, if the magnetometer 15 is located at a position that is 7mm away from a ring 12 having the greatest diameter of 51 mm and fixed on the ring plate 11 so as to be clear of interference with the traveler 13 sliding on the ring 12, the distance between the magnetometer 15 and a ring 12 having the smallest diameter of 36 mm is 14.5 mm. Therefore, even if the magnetometer 15 is fixed on the ring plate 11 at a fixed position, the magnetometer 15 can detect the traveler 13 with increased sensitivity for all the rings 12 between the smallest diameter and the greatest diameter.

[0021] Figs. 4A and 4B show the outputs of the magnetometer 15 when No. 100 count thread is spun at a spindle speed of about 20000 rpm with the distance between the magnetometer 15 and the ring 12 fixed at about 20 mm. In each of Figs. 4A and 4B, the vertical axis represents the voltage value obtained after the output of the magnetometer 15 is filtered and the horizontal axis represents time. Fig. 4A shows the output of the magnetometer 15 in the presence of the permanent magnet 14, and Fig. 4B shows the output of the magnetometer 15 in the absence of the permanent magnet 14.

[0022] In the case of the absence of the permanent magnet 14, the peaks of the output voltage are not clearly distinguishable as can be seen in Fig. 4B. In such a case, the magnetometer 15 needs to be located from the ring 12 at a distance of about 5 mm that allows the peaks of the output voltage to be clearly distinguished. For this purpose, the position at which the magnetometer 15 is mounted on the ring plate 11 needs to be adjusted in accordance with a change of the diameter of the ring 12. In addition, the magnetometer 15 that is located close to the ring 12 may interfere with yarn piecing operation. In the presence of the permanent magnet 14, on the other hand, the magnetometer 15 positioned at a spaced distance of about 20 mm from the ring 12 generates a pulse signal with a clearly distinguishable peak each time the traveler 13 makes a circuit of the ring 12, so that any yarn break may be easily determined according to the presence or absence of the pulse peak. If the magnetometer 15 is fixed at a position that is spaced at a distance of about 20 mm from a ring 12 having the smallest diameter, the position of the magnetometer 15 does not need to be changed for adjustment when the ring is replaced with a ring 12 having the greatest diameter. When the ring 12 having the greatest diameter is used, a distance of 10 mm or more is ensured between the magnetometer 15 and the ring 12, so that the magnetometer 15 is free from interference with the yarn piecing operation.

[0023] In a spinning mill, when changing the spinning condition, the rings 12 may be changed only with rings having a different diameter on the same ring plate 11. In the case wherein the size of the traveler 13 is changed depending on the thickness of the yarn to be spun, the fixing position of the traveler clearer 16 is adjusted accordingly. The traveler clearer 16 is fixed on the ring plate 11 by the screw 17 that passes through the elongated hole 16B that extends in the radial direction of the ring 12. Therefore, adjustment of the position of the traveler clearer 16 may be easily accomplished by moving the traveler clearer 16 in the radial direction of the ring 12 and then tightening the screw 17.

[0024] The above-described embodiment of the present invention has the following advantageous effects.

(1) The yarn break detector detects the magnetic traveler 13 sliding on the ring 12 fixed on the ring plate 11 thereby to determine the presence or absence of a yarn break. The yarn break detector includes a permanent magnet 14 and a magnetometer 15 that are located on or above the ring plate 11. The permanent magnet 14 magnetizes the traveler 13. The magnetometer 15 uses a magneto-impedance element to detect the magnetism of the magnetized traveler 13. Thus, the yarn break detector of the present embodiment allows the signal strength (or the pulse peak) to be increased remarkably than heretofore. Therefore, the yarn break detector of the present embodiment allows the magnetometer 15 to be arranged at a position that has not been suitable for arrangement of the electromagnetic induction type sensor or the magnetometer that detects an unmagnetized traveler. Specifically, the yarn break detector of the present embodiment eliminates the need of adjusting the position of the magnetometer 15 due to the use of a ring with a different diameter and allows the magnetometer 15 to be disposed at a position that is free from interference with the yarn piecing operation.

(2) The magnetometer 15 is located at a position that is free from interference with the traveler 13 sliding on a ring 12 fixed on the ring plate 11 and having the greatest diameter. In a spinning mill, only the diameters of the rings may be changed at the same ring plate in changing of the spinning condition. In the background art, each time the diameter of the ring is changed, the magnetometer needs to be adjusted to be positioned close to the sliding passageway of the traveler without interfering with the traveler in order to ensure the sensitivity of the magnetometer and also to prevent the magnetometer and the traveler from interfering with each other. In the present embodiment, however, the magnetometer 15 which is located at a position where the magnetometer 15 is free from interference with the traveler 13 sliding on the ring 12 fixed on the ring plate 11 and having the greatest diameter can detect successfully the traveler 13 sliding on the ring 12 fixed on the ring plate 11 and having the smallest diameter. Therefore, the position of the magnetometer 15 does not need to be changed for adjustment when the diameter of the ring 12 is changed.

(3) The permanent magnet 14 is provided so that the magnetization of the permanent magnet 14 is directed in a radial direction of the ring 12 and the magnetic pole of the permanent magnet 14 is opposed to the ring 12. The traveler 13 slides on the ring 12 while being subjected to a force acting radially outward of the ring 12 by the ballooning of a yarn being spun and wound into the cop 30. In such a position of the permanent magnet 14, therefore, the traveler 13 tends to be magnetized by the permanent magnet 14 more easily as compared to the case where the permanent magnet 14 is provided in a different manner.

(4) The magnetometer 15 is provided so that its sensor portion is directed to face the center of the ring 12. Coupled with the effects that the magnetization of the permanent magnet 14 is directed in a radial direction of the ring 12 and that the magnetic pole of the permanent magnet 14 is opposed to the ring 12, the magnetometer 15 can detect the traveler 13 with increased sensitivity because the sensor portion detects the magnetism of the traveler 13 in the position that is opposed to the direction of the magnetization of the traveler 13 magnetized by the permanent magnet 14.

(5) The traveler clearer 16 is mounted on the ring plate 11, and the permanent magnet 14 is formed integrally with the traveler clearer 16. In the spinning machine having the traveler clearer 16, the traveler clearer 16 is fixed adjustably on the ring plate 11 at a position close to the sliding passageway of the traveler 13 and free from interference with the traveler 13 so as to correspond to the diameter of the ring 12 and the shape of the traveler 13. In the present embodiment wherein the permanent magnet 14 is formed integrally with the traveler clearer 16, when the fixing position of the traveler clearer 16 is changed by adjustment in accordance with the diameter of the ring 12, the position of the permanent magnet 14 is also changed thereby to save the trouble of adjusting the position of the permanent magnet 14.

(6) Unlike an electromagnet, the permanent magnet 14 that is used as a magnet does not need any supply of energy for generating magnetic field, so that the yarn break detector is structurally simplified as compare to the case where the electromagnet is used as a magnet.

[0025] The present invention has been described in the context of the above embodiment, but it is not limited to the embodiment. It is obvious to those skilled in the art that the invention may be practiced in various manners as exemplified below.

[0026] Two magnetometers 15A may be housed in a single case 27 which is located between and diagonally behind any two adjacent rings 12, as shown in Fig. 5.

[0027] As the magnet that magnetizes the traveler 13 sliding on the ring 12, an electromagnet may be used in place of the permanent magnet 14. Referring to Figs. 6 and 7 showing an electromagnet 21, it includes a core 22 and a coil 23 which are molded by a molding resin 24 with one end of the core 22 uncovered. The electromagnet 21 further includes a support 25 of the molding resin 24 which is fixed to the ring plate 11 by the screw 17 which is inserted through a hole formed through the support 25 and an elongated hole 11A formed through the ring plate 11 and secured by a nut 26. With the support 25 fixed in place to the ring plate 11, the core 22 extends parallel to the ring plate 11 at the level of the flange 12A so that the core 22 is located in facing relation to the flange 12A. The support 25 may have a clearing member 25A that scratches off the fiber attached to the traveler 13.

[0028] When the electromagnet 21 is used to magnetize the traveler 13, the magnetic field may be generated intermittently.

[0029] The magnetometer 15 may be detachably fixed on the ring plate 11 so that the position of the magnetometer 15 is changeable. In this case, the position of the magnetometer 15 may be changed depending on the diameter of the ring 12 to be fixed on the ring plate 11 thereby to enhance the detection sensitivity of the traveler 13.

[0030] When the magnetometer 15 is detachably fixed on the ring plate 11 as in the above case, the magnetometer 15 does not necessarily need to change its fixing position depending on each of the diameters of the ring 12. The magnetometer 15 may have two fixing positions, namely, one position for the ring 12 having the greatest diameter and the other position for the ring 12 whose diameter is intermediate between the greatest diameter and the smallest diameter.

[0031] The permanent magnet 14 or the electromagnet 21 may be arranged so that the magnetization by such magnet occurs diagonally with respect to the radial direction of the ring 12. When the permanent magnet 14 or the electromagnet 21 is arranged so that the magnetization by such magnet occurs in the radial direction of the ring 12, however, the traveler 13 is magnetized more successfully as compared to the case where the permanent magnet 14 or the electromagnet 21 is arranged so that the magnetization by such magnet occurs diagonally with respect to the radial direction of the ring 12.

[0032] The magnetometer 15 does not necessarily need to be arranged so that the sensor portion is directed to face the center of the ring 12. In the arrangement of the permanent magnet 14 or the electromagnet 21 wherein the magnetization by such magnet occurs diagonally with respect to the radial direction of the ring 12, if the magnetometer 15 is arranged so that the sensor portion of the magnetometer 15 is directed diagonally in the radial direction of the ring 12 at an angle corresponding to the angle made between the direction of magnetization of the permanent magnet 14 or the electromagnet 21 and the radial direction of the ring 12, the sensitivity of the magnetometer 15 is enhanced.

[0033] The permanent magnet 14 or the electromagnet 21 may be fixed on the ring plate 11 separately from the traveler clearer 16, provided that the magnetometer 15 is fixed at such a position that does not cause magnetic saturation of the permanent magnet 14 or the electromagnet 21.

[0034] The cross-sectional shape of the ring plate 11 is not limited to an inverted U shape, but may be a shape of crank so that the magnetometer 15 is mounted to the rear wall of the ring plate 11. Alternatively, it may be so arranged that the ring plate 11 of an inverted-U shaped cross section has a mounting plate fixed to the rear wall of the ring plate 11 and extending to a level that is higher than the upper surface of the ring plate 11 and also that the magnetometer 15 is mounted to the mounting plate.

[0035] The yarn break detector of the present invention is applicable to a ring twisting machine, as well as to the ring spinning machine as described above.

[0036] A spinning machine has a ring plate, a ring fixed on the ring plate and a traveler slidably mounted on the ring. The traveler is made of a magnetic material. A yarn break detector of the spinning machine detects the traveler to determine presence or absence of a yarn break. The yarn break detector is characterized in that the yarn break detector includes a magnet and a magnetometer that are located on or above the ring plate. The magnet magnetizes the traveler. The magnetometer uses a magneto-impedance element to detect magnetism of the magnetized traveler.

Claims

1. A yarn break detector of a spinning machine, wherein the spinning machine has a ring plate (11), a ring (12) fixed on the ring plate (11) and a traveler (13) slidably mounted on the ring (12), wherein the traveler (13) is made of a magnetic material, wherein the yarn break detector detects the traveler (13) to determine presence or absence of a yarn break, the yarn break detector being characterized in that
the yarn break detector includes a magnet (14, 21) and a magnetometer (15, 15A) that are located on or above the ring plate (11), wherein the magnet (14) magnetizes the traveler (13), wherein the magnetometer (15, 15A) uses a magneto-impedance element to detect magnetism of the magnetized traveler (13).

2. The yarn break detector according to claim 1, characterized in that the magnetometer (15, 15A) is located at a position that is free from interference with the traveler (13) on the ring (12) having a greatest diameter.

3. The yarn break detector according to claim 1 or 2, characterized in that the magnet (14) is provided so that magnetization of the magnet (14) is directed in a radial direction of the ring (12) and a magnetic pole of the magnet (14) is opposed to the ring (12).

4. The yarn break detector according to any one of claims 1 through 3, characterized in that a traveler clearer (16) is mounted on the ring plate (11) and the magnet (14) is formed integrally with the traveler clearer (16).

5. The yarn break detector according to any one of claims 1 through 4, characterized in that the magnet (14) is a permanent magnet.

6. The yarn break detector according to claim 3, characterized in that the magnetometer (15, 15A) is provided so that a sensor portion of the magnetometer (15, 15A) is directed to face a center of the ring (12).

Drawing