Spinning device

Abstract: The present invention is able to detect yarn defects with great accuracy by measuring the tension of the yarn. The present invention holds the fastened spun yarn in a bent state by a tension sensor immediately before the winding package. The changes in tension of the fastened spun yarn are measured by this tension sensor and the evaluation of yarn defects is performed by an evaluation part based on the results of this measurement.

Description: Field of the Invention The present invention relates to a spinning device for forming a yarn by imparting a twist into a supplied fiber bundle and in particular, to the detection of yarn defects by measuring the tension of the yarn. Background of the Invention On conventional spinning devices (see EP-A-289 010), the short staple fiber bundle of cotton or the like or the long staple fiber bundle of the wool or the like (sliver) drawn out at the draft part are formed into a fastened spun yarn by being imparted with a twist by a spinning part (air spinning nozzle, false twister) and wound on a winding package while being traversed at the winding part (traverse device, friction roller). The above mentioned fastened spun yarn imparted with a twist comprises mainly a fiber bundle of which only the surface has been twisted. Due to this, if the fastening of the fiber bundle loosens while spinning the fastened spun yarn swells and becomes thicker and also becomes thinner by a reduction in the bundle of the fiber bundle thus generating stretched easily breakable weak yarn parts (defective yarn). Apart from this, defects such as slub, fat yarn, thin yarn and the like are generated on the fastened spun yarn. If this defective fastened spun yarn is wound on the winding package and used for weaving, a variety of problems such as breakage of the fastened spun yarn are caused. Accordingly, on conventional spinning devices, the fastened spun yarn is passed through an electrostatic type or optical type slub catcher before being wound on the winding package and by measuring the changes in cross section (diameter changes) of the fastened spun yarn, the various yarn defects are detected. However, the method that detects a variety of yarn defects by measuring the cross sectional changes of a fastened spun yarn by a conventional slub catcher is effective when the amount of cross sectional change is large but when the cross sectional change is minute, it is necessary to increase the sensitivity. In particular, in the aforementioned weak yarns, as the fastening of the fiber bundle loosens thus swelling the bundled fiber and slightly fattening the yarn or where the fiber bundle decreases thus slightly thinning the yarn, if the accuracy of the slub catcher is increased too much, erroneous detection may arise caused by noise etc. and thus weak yarn may can not be detected with great precision. In particular, as spinning devices wind the yarn continuously fed by the spinning part on the winding part, there is less tension breakage even if a weak yarn is generated and the weak yarn may be wound on the winding package. It should be noted that the problem of weak yarns is not limited to spinning devices of fastened spun yarns but is also relevant to the spinning devices of true twisted yarns. Summary of the Invention In order to solve these problems, it is an object of the present invention to propose a spinning device that is able to detect yarn defects with great sensitivity by measuring the tension of the yarn. In order to achieve the aforementioned object, a first aspect of the present invention is a spinning device provided with a spinning part that forms spun yarn by imparting a twist in supplied fiber bundle and a winding part for winding that yarn, arranged with a tension detection part that detects yarn defects by detecting the tension of the yarn. Accordingly, by detecting the yarn tension that changes in response to the defective state of the yarn, defects of the yarn and in particular weak yarn part may be detected. Furthermore, in addition to the first aspect, a thickness detection part that detects the yarn defects by measuring the thickness of the yarn is arranged. Accordingly, by measuring the thickness of the yarn, a thick yarn part, a thin yarn part and slub may be detected and by measuring the tension, a weak yarn part may be detected. Yet further, in addition to the first aspect, the winding part winds the yarn by traversing and the tension detection part is arranged on that winding part immediately before the traversing of the yarn and detects abnormal values of the winding tension. Accordingly, yarn defects may be detected as well as stitching and straight winding generated on the package wound by traversing the yarn. Yet further still, in addition to the first aspect, the spinning part is a fastened spun yarn spinning part that spins fastened spun yarn. Accordingly, when a weak yarn part is generated in the fastened spun yarn, as the restriction force of the wrapped fibers that restrict the core fiber bundle of the yarn decreases and the tension of the yarn decreases, a weak yarn part may be detected with great sensitivity due to tension changes. A second aspect is a spinning method that forms spun yarn by imparting a twist in supplied fiber bundle and detects yarn defects by detecting the tension of the yarn. Accordingly, by detecting the tension of the yarn that changes in response to the defective state of the yarn, defects of the yarn and in particular a weak yarn part may be detected. Furthermore, in addition to this second aspect, if a defect is detected, the spinning is stopped. Accordingly, as the spinning is automatically stopped when a defect is detected, spinning may be quickly restarted after removing the yarn defect. Yet further, in addition to the second aspect, the aforementioned yarn is a fastened spun yarn. Accordingly, when a weak yarn part is generated in the fastened spun yarn, as the restriction force of the wrapped fibers that restrict the core fiber bundle of the yarn decreases and the tension of the yarn decreases, a weak yarn part may be detected with great sensitivity due to tension changes. Brief Description of the Drawing Figure 1 is a schematic perspective drawing showing the spinning device of the present invention. Figure 2 is a front view showing the spinning device of the present invention. Figure 3 is a sectional view along the line III-III of Figure 2. Figure 4 is a sectional view showing the structure of the tension sensor comprising the tension detection part. Figure 5 is a front view showing the structure of the tension sensor comprising the tension detection part. Figure 6 is a schematic diagram showing the evaluation part of the tension sensor and the spinning controller. Figure 7 is a schematic perspective part showing a modification of the spinning device. Figure 8 is a graph showing the results of measuring a weak yarn part of the fastened spun yarn by a tension sensor and slub catcher. Figure 9 is a graph showing the results of measurment by the tension sensor when yarn end dropping occurs on the winding package. Figure 10 is a graph showing the results of measurment by the tension sensor when a straight winding occurs on the winding package. Detailed Description of the Preferred Embodiments Hereafter, the spinning device and method of the present invention will be described with reference to the drawings. Firstly, the spinning device of the present invention will be described based on Figures 1 through 4. In Figure 1, a spinning device 1 comprises a plurality of juxtaposed spinning units 1u as shown in Figure 2 and is provided with an auto-running type yarn piecing device 12 (also shown in Figure 3) that moves reciprocally in the longitudinal direction of the frame of the spinning device 1 along each spinning unit 1u. The spinning unit 1u is arranged with, in series from the upstream side to the downstream side, a draft part 2, a spinning part 5 comprising an air spinning nozzle 3 and false twister 4, a delivery roller 6, a tension detection part 8 comprising a tension sensor 7 or the like that measures the tension of a fastened spun yarn Y, a slack tube 9 that removes looseness from the fastened spun yarn Y by suction air, a slub catcher that 10 that measures the thickness of the fastened spun yarn Y and a winding part 11. The draft part 2 comprises a pair of backrollers 15, a pair of middle rollers 17 provided with a apron belt 16 and a pair of front rollers 18. Of each pair of draft rollers, the pair of front rollers 18 of all the units are driven in unison by the arrangement of a bottom roller on a line shaft common to all units but all other rollers are able to stop individually for each unit. The air spinning nozzle 3 is arranged downstream of the pair of front rollers 18, is arranged with pressurized air blowing holes open in the inner side surface of the nozzle in a tangential direction and blows compressed air from those pressurized air blowing holes. Due to this, a rotating air current spinning in the direction opposite the false twister 4 (described later) twist application direction is generated in the air spinning nozzle 3. Furthermore, the air spinning nozzle 3 is connected to a pressurized supply source that supplies compressed air via air supply piping (not shown in the drawings) and a mechanical valve or the like and stops the supply of compressed air by the operation of that mechanical valve. It should be noted that the aforementioned pressure air blowing holes are arranged angled facing towards the yarn running direction, in short, the downstream and a suction air current is easily generated at the inlet side of the air spinning nozzle 3. The false twister 4 comprises a pair of rollers 21,22 supported in contact with each other and with their axial directions crossing over. Each roller 21,22 is a hollow roller of which a thin cylindrical member comprised of an elastic material such as rubber or the like is fitted onto the roller core and moreover, is formed into a barrel shape with a cross section where the central part is expanded with respect to both ends of the roller's periphery. Also, each of the rollers 21,22 are wound with a belt on each between a pulley (not shown in the drawings) arranged on the end of that rotating shaft and a pulley fixed to the rotation shaft of the motor and are rotated in synchronicity at the same peripheral speed by that motor. Due to the air spinning nozzle 3 and false twister 4, the fiber bundle S drawn out by the draft part 2 is formed into fastened spun yarn Y. This fastened spun yarn Y forms core fibers by the fibers lined up approximately straight and the winding fibers around the periphery of that core fibers in a spiral wrapped shape. A nip roller 25 is positioned freely in contact with the delivery roller 6. The nip roller 25 is forced against the delivery roller 6 in a clockwise direction (of the drawing) by a spring (not shown in the drawings) and is able to deliver the fastened spun yarn Y by pressing on that delivery roller 6. The slub catcher 10 detects yarn defects such as slub, a thick yarn part and a thin yarn part including a weak yarn part or the like and also yarn breakages of the fastened spun yarn Y by measuring the cross sectional change (thickness) of the fastened spun yarn Y and outputs a thickness measurement signal when any of these are measured. The winding part 11 is supported so as to freely rotate on a cradle arm and moreover winds fastened spun yarn Y on the winding package P that rotates by being pressed on the friction roller while traversing the fastened spun yarn Y by a traverse device (not shown in the drawings). The yarn piecing device 12 is positioned on a yarn piecing car 30 which runs freely and is common to the spinning devices as shown in Figure 3 without individual positioning at each spinning unit 1u. In short, as shown in Figure 3, the yarn piecing device 12 is positioned inside a reversed c-shape space 31 of the spinning device 1 and carries out yarn piecing by moving in front of a winding unit 1u where yarn piecing is required while being guided by a rail. This yarn piecing car 30 has a device having yarn piecing functions called a knotter 32 and is provided with a suction pipe (spinning part side yarn suction member) 33 that has an approximately circular suction hole in the tip, and a suction mouth (winding side yarn suction member) 34 that has an elongated suction mouth in the tip. Next, the tension detector 8 will be described with reference to Figures 4 through 6. In Figures 4 through 6, the tension detector 8 has the tension sensor 7 that measures the tension of the fastened spun yarn Y which has had a twist imparted by the false twister 4, and an evaluation part 51 that evaluates the defect of the fastened spun yarn Y based on the measurement signal measured by the tension sensor 7. Firstly, as shown in Figures 4 and 5, the tension sensor 7 comprises an elastic plate 36 positioned inside the sensor main body 35, a guide rod (yarn guide support body) 37 and a strain measurement member 38. It should be noted that the tension sensor 7 has a function that measures the tension but if used simply for the detection of weak yarn parts, may use a detection member such as a micro-switch or the like that operates by detecting the tension as there is no need for the tension to be measured. The base of guide rod (yarn guide support body) 37 is fixed to the elastic plate 36 so that it projects at right angles (approximately right angles) from the elastic plate 36. Furthermore, the guide rod 37 is inserted in the cylinder part of the inner case as shown in Figure 1 and that tip side projects from the cylinder part to the outer part. A yarn guide 39 is supported on the tip of the guide rod 37 so as to be freely removable. The guide rod 37 crosses over the bent plane (triangular plane) A, shown in Figure 5, formed by the fastened spun yarn Y bent due to the delivery roller 6 (nip roller 25), yarn guide 39 and slub catcher (thickness detector) 9. A space is equally arranged between the outer peripheral surface of the guide rod 37 and the inner peripheral surface of the cylinder part and the guide rod 37 (in short the yarn guide 39) is able to move within the gap formed in this space. In short, the cylinder (strictly speaking, the tip of the cylinder part) forms a stopper that restricts the movable range of the guide rod 37. The elastic plate 36 comprises an enamelling metal plate or the like and is positioned inside the inner space of the sensor main body 35 parallel to the aforementioned plane A (or fastened spun yarn Y). Furthermore, as shown in Figure 5, the ends of the elastic plate 36 in the direction in which the composite force F of the tension T applied in the upstream (delivery roller 6 side) and downstream (winding package P side) either side of the guide rod 37 is exerted, are each supported by a bolt or the like on the sensor main body 35. It should be noted that only one support point is also possible. Due to this, when the guide rod 37 is moved by the aforementioned composite force F, as that composite force F is transmitted to the elastic plate 36, the elastic plate 36 supported at two points is wave shape deformed between the two support points by the basal end of the guide rod 37. In short, when the guide rod 37 moves, the elastic plate 36 undergoes a wave deformation such that the side in which the composite force F is acting sinks by moving away from the fastened spun yarn Y and the opposite side bulges by moving near the fastened spun yarn Y. It should be noted that it is preferable for the thickness of the elastic plate to be such that it may be deformed into a wave shape corresponding to minute changes in tension of the fastened spun yarn. The strain measurement part 38 comprises a plurality of strain gauges (for example, a metal grade strain responsive resistor) 40 arranged on the elastic plate 36. Each strain gauge 40 is mounted respectively on each side of the guide rod 37 on the elastic plate 36 being a place where the wave deformation of the elastic plate 36 conspicuously appears in the direction in which the composite force F acts and measures the extension or contraction (strain) of the elastic plate 36 by the wave deformation (troughing, swelling). Also, each strain gauge 40 is connected to a controller board 45 and the controller board 45 outputs the amount of strain (tension of the fastened spun yarn Y) of the elastic plate 36 as a tension measurement signal to the evaluation part 51 (shown in Figure 6) included in the spinning controller 50. Furthermore, an additional controller board 45a having functions for each model is embedded when necessary in the filled resin layer 46 such that the inner space of the sensor main body 35 is sealed. It should be noted that the strain gauge 40 may be positioned attached to the elastic plate 36 or may be positioned directly on the elastic plate 36 by printing or the like. The tension sensor 7 comprised as above is fixed between the delivery roller 6 and the slub catcher (thickness detector) 10 being after the slack tube (slack removal tube) 9, such that the flange 35A (shown in Figure 5) formed on the sensor main body 35 is mounted on the spinning device 1 such that the running direction of the fastened spun yarn Y passing through the delivery roller 6 is changed by bending the yarn Y towards the winding package P. The spinning controller 50 connected to the controller board 45 of the tension sensor 7 comprises mainly an evaluation part 51 and spinning control part 52 as shown in Figure 6. When the tension measurement signal output from the tension sensor 7 and the thickness measurement signal output from the slub catcher 10 are input, the evaluation part 51 evaluates whether a defect of the fastened spun yarn Y (slub, thick yarn part, thin yarn part and weak yarn part) or a winding error such as stitching or straight winding of the winding package P has occurred by comparing these measurement signals with the standard tension values and the standard thickness values of a predetermined range. In actuality, the evaluation part 51 evaluates the generation of weak yarn part of a fastened spun yarn Y and generation of straight winding or stitching of the winding package by comparison of the tension measurement signals output from the tension sensor 7 and the standard tension values. In short, the standard tension values corresponding to a weak yarn part of a fastened spun yarn Y, straight winding and stitching of the winding package are memorised in the evaluation part 51. The standard tension values are memorised separately for a weak yarn part of fastened spun yarn Y and stitching and straight winding of the winding package P and are data relating to the average value of the tension decrease, the amplitude of that average value and the amplitude time. Thus a weak yarn part Y generated in the fastened spun yarn Y is generated due to the decrease of the restriction force of the wrapping fibers that restrict the core filament and as shown in Figure 8 which will be described later, the aforementioned data is that where the tension has severely decreased, that amplitude is low and the amplitude time is relatively long. Furthermore, stitching of the winding package P is a phenomenon whereby the fastened spun yarn Y traversing on the winding package P suddenly drops onto the winding tube of the winding package P and then resumes a traverse operation. As shown in Figure 9 which will be described later, the aforementioned data is that where the tension has severely decreased, that amplitude is small and the amplitude time is short. Furthermore, straight winding of the winding package P is a phenomenon where the fastened spun yarn Y traversing on the winding package P drops onto the winding tube of the winding package P and then resumes the traversing operation after the fastened spun yarn Y has been wound on the winding tube for a certain time period. As shown in Figure 10 which will be described later, the aforementioned data is that where the tension has decreased, that amplitude is large and moreover the amplitude time is long. Yet further, the evaluation part 51 evaluates the generation of slub, thick yarn part or thin yarn part of the fastened spun yarn by comparing the thickness measurement signal output from the slub catcher 10 and the standard thickness values. In short, the standard thickness values that correspond to slub and thick yarn of the fastened spun yarn Y are memorised in the evaluation part 51. The standard thickness value is data having a predetermined permissible range relating to the thickness (cross section) of normal (no defects) fastened spun yarn Y. In this way, the evaluation part 51 is input with data of weak yarn part of the fastened spun yarn Y, and straight winding and stitching of the winding package, compares the standard tension values and the tension measurement signal output from the tension sensor 7 and when these tension measurement signals are equivalent to the data of each standard tension value, a weak yarn part defect signal, stitching defect signal and straight winding defect signal corresponding to the data is output to the spinning control part 52. Further, when this thickness measurement signal is higher than the range of the standard thickness value due to the comparison of the standard thickness value and thickness measurement signal output by the slub catcher 10, the evaluation part 51 outputs a thick yarn defect signal to the spinning control part 52 and when the thickness measurement signal is lower than the range of the standard thickness value, it outputs a thin yarn defect signal to the spinning control part 52. Then, the spinning control part 52 that is entered with each defect signal from the evaluation part stops the spinning and the defect is displayed by a printer or alarm device (not shown in the drawings). The structure of the spinning device 1 of the present invention is as described above but next, the method of spinning the fastened spun yarn Y using this spinning device 1 will be described. As in Figure 1, the sliver S (fiber bundle) wound in a spiral shape in a cylindrical sliver can K is sequentially drafted by passing through each of rollers 15,17,18 of the drafter part 2 driven while in contact with each other and is delivered to the false twister 4 while a spinning air current from the pressured air blowing holes of the air spinning nozzle 3 positioned downstream of the pair of front rollers 18 is generated in a direction opposite the twisting direction of the false twister 4. Also, when passing through the pair of rollers 21,22 of the false twister 4, the sliver S (fiber bundle) is formed into the fastened spun yarn Y by being imparted with a twist and then the yarn Y is pulled from between the rollers 21,22 of the false twister 4 by the delivery roller 6 and nip roller 25. Thereafter, the fastened spun yarn Y in which a twist has been imparted is flexed by the guide rod 37 of the tension sensor 7 of the tension detection part 8, passes through the slack tube 9 and slub catcher 10 and is wound on the winding package P by a friction roller 26 while being traversed by a means (not shown in the drawings). In this way, when the fastened spun yarn Y passes the guide rod 37 of the tension sensor 7, the guide rod 37 is pushed by the composite force F (shown in Figure 5) of the tension T applied to the upstream side (delivery roller 6 side) and downstream side (winding package P side) of the fastened spun yarn Y in the bent state thus deforming the elastic plate 36 to a wave shape. Due to this, each strain gauge 40 continuously measures the extension/contraction (strain) of the elastic plate 36 by the wave deformation of the elastic plate 36 and tension measurement signals are sequentially output to the spinning controller 50 (evaluation part 51) via the control board 45. Furthermore, simultaneous with this, the slub catcher 10 also continuously measures the thickness of the fastened spun yarn Y and outputs the thickness measurement signals to the spinning controller 50 (evaluation part 51). In short, when a weak yarn part (including stitching or straight winding) is generated in the fastened spun yarn Y, the tension of the fastened spun yarn Y decreases and the displacement of the guide rod 37 is less than the displacement due to the tension of a normal (no defects) fastened spun yarn Y and the wave deformation of the elastic plate 36 also decreases. In this way, each strain gauge 40 measures the increase or decrease of the wave deformation of the elastic plate 36 corresponding to a weak yarn part generated in the fastened spun yarn Y, stitching or straight winding generated on the winding package P and sequentially outputs the tension measurement signals to the spinning controller 50 (evaluation part 51) via the controller board 45. When the spinning controller 50 is entered with each measurement signal, this evaluation part 51 evaluates whether or not there has been any generation of defects of the fastened spun yarn Y, any stitching or straight winding on the winding package. 1 ○ Firstly, the evaluation part 51 does not output a defect signal to the spinning control part 52 when it has been evaluated that no defect has been generated in the fastened spun yarn Y and there is no stitching or straight winding in the winding package by the conditions whereby the tension measurement signal from the tension sensor 7 does not correspond to the standard tension values and the thickness measurement signal from the slub catcher 7 is within the standard thickness value range. Accordingly, the spinning control part 52 of the spinning controller 50 executes continuous spinning. 2 ○ Furthermore, the evaluation part 51 outputs a weak yarn defect signal, stitching defect signal and straight winding defect signal corresponding to the defect to the spinning control part 52 by evaluating that a weak yarn part has been generated in the fastened spun yarn Y or there is stitching or straight winding on the winding package by the conditions whereby the tension measurement signal from the tension sensor 7 corresponds to the data of the standard tension values. Also, the spinning control part 52 of the spinning controller 50 input with the defect signal, stops the spinning and informs the operator by an alarm operation device (not shown in the drawings) particularly when there is stitching or straight winding of the winding package P. 3 ○ Furthermore, the evaluation part 51 outputs a thick yarn defect signal or thin yarn defect signal corresponding to those defects to the spinning control part 52 by evaluating that slub or a thick yarn part has been generated in the fastened spun yarn Y by the conditions whereby the thickness measurement signal from the slub catcher 10 is above the standard thickness value range or by evaluating that a thin yarn part has been generated in the fastened spun yarn Y by the conditions where by the thickness measurement signal from the slub catcher 10 is lower than the standard thickness value range. The spinning control part 52 of the spinning controller 50 input with the defect signal then stops the spinning. When the spinning control part 52 of the spinning controller 50 is input with the defect signal of the fastened spun yarn Y as described above, the rollers 15,17,18 of the draft part 2 stop, the supply of sliver S (fiber bundle) stops, the air blowing of the air spinning nozzle 3 stops and the yarn piecing device 12 moves to the spinning unit 1u where the defect in the fastened spun yarn Y has been generated. Then, the weak yarn part, slub or thick yarn part of the fastened spun yarn Y wound on the winding package P is cut and removed by a means not shown, the fastened spun yarn Y at the exit of the air spinning nozzle 3 is carried to the knotter 32 by the suction pipe 33 of the yarn piecing device 12, the fastened spun yarn Y end of the winding package P is carried to the knotter 32 by the suction mouth 34, yarn piecing is performed by this knotter 32 and the spinning device is restored to a state where spinning is possible. Furthermore, when stitching or straight winding is generated on the winding package P, an alarm is generated by the aforementioned alarm device and the operator is able to restore the device to a state where spinning is possible by correcting the stitching or straight winding of the winding package P. It should be noted that this process may be automatically performed by the piecing device 12. It should be noted that on the spinning device 1 and the spinning method of the present invention, a description of a tension sensor 7 comprising the tension detector 8 arranged between the delivery roller 6 and slub catcher 10 and which measures the tension of the fastened spun yarn Y has been given but it is not limited to this and as shown in Figure 7, it may measure the tension of the fastened spun yarn Y by being arranged between delivery roller 6 and false twister 4. However, if the tension sensor or micro-switch or the like comprising the tension detector 8 is arranged downstream of the delivery roller 6 (near to the package P), the tension changes of the spinning part 5 can not be received (due to interruption by the delivery roller 6) and weak yarn part detection can be performed correctly. It should be noted that in Figure 7, the numbering of the members is the same as that for Figure 1. In this case, the tension sensor 7 is only able to detect the defects (weak yarn part) of the fastened spun yarn Y by a method similar to that shown above. Furthermore, if the tension sensor 7 is arranged directly on the spinning device 1, the strain gauges 40 may inadvertently measure the deformation of the elastic plate 36 caused by vibration generated at the spinning device thus by installing a piezoelectric element (vibration detection sensor) on the tension sensor 7, the aforementioned vibrations may be detected, the measurement signal caused by the vibrations may be removed from the tension measurement signal of the strain gauge 40 and the measurement sensitivity by the strain gauges 40 improved. Yet further, if the tension that changes for each defect (weak yarn part, thin yarn part, slub and thick yarn part) generated in the fastened spun yarn Y is measured by the arrangement of the tension sensor 7 upstream from the winding package P, the defects (weak yarn part, thin yarn part, slub and thick yarn part) of the fastened spun yarn Y may be measured without using a slub catcher 10. In particular, as shown in Figure 7, by arranging the tension sensor 7 between the delivery roller 6 and false twister 4, the vibration from the traversing and winding on the winding package P is cut off by the delivery roller 6 and the defects (thin yarn, slub and thick yarn) of the fastened spun yarn Y may be easily and accurately measured without being influenced by this vibration. An example where the tension of the fastened spun yarn Y imparted with a twist by the false twister is measured by the tension sensor 7 has been described but the spinning device 1 and the spinning method of the present invention is not limited to this and the present invention may be applied to a spinning device of a true twist yarn. Next, in the Figure 8 through 10, the results of measuring the tension changes of the fastened spun yarn Y by the tension sensor 7 for a weak yarn part of the fastened spun yarn Y and stitching and straight winding of the winding package P are shown. In Figure 8, the measurement result of the tension sensor 7 and slub catcher 10 when a weak yarn part is generated in the fastened spun yarn Y are shown. When measuring by the tension sensor 7, a weak yarn part may be detected with high sensitivity even when the change in the thickness of the fastened spun yarn Y is small due to the conspicuous decrease in tension of the weak yarn part. In contrast with this, when the slub catcher 10 measures a weak yarn part, the weak yarn part can not be detected by the slub catcher 10 as the change in the thickness of the fastened spun yarn Y is minute conmpared to when the fastened spun yarn Y is normal. In Figures 9 and 10, the measurement results of the tension sensor 7 when stitching and straight winding respectively are generated on the winding package P are shown. In both drawings, when measuring by the tension sensor 7, stitching and straight winding on the winding package P may be detected due to the conspicuous decrease in tension of the stitching and straight winding part. It should be noted that stitching was generated twice in Figure 9 and straight winding was generated three times in Figure 10. In Figures 8 through 10, when the measurement results of a weak yarn part of a fastened spun yarn Y and the stitching and straight winding of the winding package detected by the tension sensor 7 are compared, it is confirmed that there is a conspicuous difference for the measurement results for each defect (weak yarn part, stitching and straight winding). In short, the measurement result of a weak yarn part generated in the fastened spun yarn Y has charateristics whereby there is a noticeable decrease in tension of the fastened spun yarn Y, that amplitude is small and the amplitude time is long. Furthermore, the measurement result of stitching of the winding package P has charateristics whereby there is a remarkable and sudden decrease in tension of the fastened spun yarn Y and then resumption to previous levels. Yet further, the measurement result of straight winding of the winding package P has charateristics whereby there is a decrease in tension, that amplitude is large and the amplitude time is long. In this way, if the data of the standard tension values memorised in the evaluation part 51 are set based on the measurement results of each defect (weak yarn, stitching and straight winding), a weak yarn part generated in the fastened spun yarn Y and stitching or straight winding generated on the winding package P may be reliably evaluated only by measurement of the tension of fastened spun yarn Y. It should be noted that if the tension change of slub, thick yarn part or thin yarn part generated in the fastened spun yarn Y is measured and memorised as the standard tension value data of the evaluation part 51, it is possible for slub, thick yarn part or thin yarn part in the fastened spun yarn Y to be simultaneously evaluated and detected based on the measurement result of the tension sensor 7. The tension detector 8 may be arranged with for purpose of detecting a weak yarn part or the like by the arrangement of a detection member (micro-switch etc.) that operates when the tension is lower than the set value. An arrangement according to a first aspect of the present invention is able to detect yarn defects such as a weak yarn part or the like with great sensitivity and improve the quality of the manufactured yarn as the tension of the yarn that changes due to the defect such as a weak yarn part or the like generated in the yarn is detected by a tension detector and the presence or absence of a yarn defect is detected based on that detection result. In addition to this first arrangement, as the tension of the yarn is detected by the tension detector and the thickness of the yarn is detected by a thickness detector, the present invention is able to detect the yarn defects with greater sensitivity by discriminating between a yarn defect where there is a change in the thickness and a yarn defect where thickness differences do not easily appear and thus the present invention is able to improve the quality of the manufactured yarn. In addition to the first arrangement, an improved winding package may be formed as winding errors such as stitching or straight winding in the winding part may also be reliably detected in addition to the detection of yarn defects by the arrangement of a tension detector immediately before the traversing of the yarn and detection of the yarn tension. In addition to the first arrangement, as on a fastened spun yarn spinning device, yarn defects such as a weak yarn part or the like are easily generated and if that weak yarn is generated, the yarn tension drastically decreases, the weak yarn part of the fastened spun yarn may be reliably detected by detection of that tension change. An arrangement according to a second aspect of the present invention is able to detect yarn defects such as a weak yarn part or the like with great sensitivity and improve the quality of the manufactured yarn as the tension of the yarn that changes due to the yarn defect is detected by a tension detector and the presence or absence of a yarn defect is detected based on that detection result. In addition to this second aspect, the yarn defect may be removed and spinning may be quickly restarted thus producing good quality yarn without decreasing the yarn production properties as the spinning is automatically stopped when a yarn defect is detected. In addition to this second aspect, as yarn defects such as a weak yarn part or the like are easily generated when spinning fastened spun yarn and if that weak yarn part is generated, the yarn tension drastically decreases, the weak yarn part of the fastened spun yarn may be reliably detected by that tension change.

Claims: A spinning device provided with a spinning part (5) having an air spinning nozzle (3) and a yarn tension sensor (7) characterized in that the yam tension sensor (7) comprises an elastic plate (36), a guide rod (37) fixed approximately at right angles to the elastic plate (36) and a yarn guide (39) supported on the tip of a guide rod (37), wherein a space is equally arranged between the outer peripheral surface of the guide rod (37) and the inner surface of a cylindrical part of a supporting member (38) so that the guide rod (37) is movable within this space, and strain gauges (40) are arranged on the elastic plate (36). Spinning device according to claim 1, characterized in that the ends of the elastic plate (36) in the direction on which the composite force (F) of the yarn tension (T) applied in the upstream and downstream side of the guide rod (37) is exerted, are supported. Spinning device according to claim 2, characterized in that a strain gauge (40) is mounted on each side of the guide rod (37) on the elastic plate (36) where the deformation of the elastic plate (36) appears in the direction, in which the composite force (F) acts.

Inventors: KAWASHIMA KIYOTAKA, KAWASHIMA, KIYOTAKA
Applicants: MURATA MACHINERY LTD, MURATA KIKAI KABUSHIKI KAISHA
Application year: 1997
Main classification: D01H13
IPC codes: B65H59, D01H13