Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B15/00—Details of, or auxiliary devices incorporated in, weft knitting machines, restricted to machines of this kind
  • D04B15/38—Devices for supplying, feeding, or guiding threads to needles
  • D04B15/48—Thread-feeding devices

Definitions

• This invention relates to a device for feeding yarns to textile machines, such as circular or straight knitting machines, that can be adapted either to machines in which the yarn consumption rate is constant or to machines in which the yarn is knitted discontinuously (it is a well-known fact that said discontinuous yarn consumption induces periodic changes in the yarn's tension that can combine with tension variations due to irregularities in the yarn itself in negatively influencing the quality of the resulting fabric and the continuity of its production).
• the device forming the object of this invention can also be used in certain stages of the spinning process, e.g. to feed yarn at a uniform tension to twisting or stranding machines, or the like.
• This invention refers to a yarn feeder device comprising a yarn tension sensor and a yarn feed roller around which the yarn is wound to prevent any relative slipping, the roller being motorized by means of a variable-speed motor complete with a rotation sensor and governed by a microprocessor-controlled electronic unit suitable for adjusting the speed of the roller as a function of the signal coming from said tension sensor.
• the device comprises a pulley for carrying the yarn, wherein the incoming and outgoing lengths of yarn together form a relatively narrow, or substantially near-zero angle ( ⁇ ).
• the pulley is suspended from a sensitive element of the tension sensor suitable for transmitting a signal to said feed roller motor control unit that is proportional to the resultant of the forces exerted on the pulley by the yarn, and the control unit has a program resident in its memory for keeping the value of said resultant of the forces (corresponding to the yarn tension) within a pre-established range of yarn tensions by adjusting the speed of the motor, and consequently of the feed roller.
• the yarn thus brings a force to bear on the tension sensor that is approximately twice the actual tension of the yarn, thereby increasing the sensor's sensitivity by comparison with known feeder devices.
• the electronic control unit of the device can also be interfaced with the machine to which the device is attached in order to receive data (e.g.
• the pulley supporting block comprises a U-shaped bracket housing the pulley, the stud supporting the pulley being attached to the ends of said bracket.
• the sensor is of the slender cylinder-shaped type and is glued to a flat or concave seat coinciding with the end of the rod, with its axis lying parallel to said rod, said U-shaped bracket resting up against the sensor on the side opposite said seat on the rod.
• the pulley block bracket is hinged onto one free end of a tab to which a bending sensor is attached, composed for instance of one or more strain gauges.
• the tension sensor, and consequently also a stud from which the pulley carrying the yarn is suspended can be solidly attached to the body of the feeder device, or applied to the free end of a yarn take-up rod.
• Figs. 1 and 2 schematically illustrate an elevational view and a view from above (along ll-ll of Fig. 1), respectively, of the device according to a first embodiment of the invention;
• Figs. 3 and 4 show partial views from above along Ill-Ill and IV-IV of Fig.
• the device according to the invention has a plate-shaped body 1 , to which a variable-speed electric motor (e.g. of the brushless, direct-current type) and a corresponding electronic control unit (not illustrated in the drawing) are attached.
• a variable-speed electric motor e.g. of the brushless, direct-current type
• a corresponding electronic control unit not illustrated in the drawing
• the device has a revolving roller 3 mounted co-axially on the output shaft of the motor, a plate-type yarn tensioner 5, a rod 7 swinging around an axis X- X, a rod-returning spring 9, an arched blade serving as a rabbet 10 for the rod 7, and a graduated segment 12 of a circle whose center lies on the axis X-X, suitable for identifying the angular position of the rod 7.
• the roller 3 has a cylindrical outer surface suitable for generating a friction with the yarn wound thereon, made of elastomer for instance, or with a hard, rough metal surface layer.
• the plate-type yarn tensioner comprises a pair of plates 5A, 5B (Fig.
• the spring 9 is a traction spring that obliges the rod 7 to turn in the direction of the arrow F1 , one end of the spring being attached by means of a screw to the periphery of the hub 7A of the rod, and the other end being fixed by means of another screw to the periphery of a bush 8 attached to the front of the body 1 by means of a swivel screw 8A (Fig. 4).
• the tension on the spring 9 can be adjusted by loosening the screw 8A, turning the bush 8 one way or the other, and then tightening it again in the required position.
• a block 11 is attached to the free end of the rod 7 and comprises an idle pulley 13 with an outer race 13A, and a holder for the pulley substantially composed of a bracket 11A bent into a U shape, with the stud 11 B supporting the pulley 13 caulked onto its ends.
• the block 11 is kept axially on the rod 7 with some degree of clearance by means of a pair of elastic rings 7B inserted in corresponding grooves (not illustrated) in the rod 7, and rests against the rod 7 with a pressure sensor 15 sandwiched between the two and attached to the rod, e.g. by means of glue, in a cavity 7C in said rod.
• the pressure sensor 15 is electrically connected to the electronic control unit contained in the body 1 , by means of electric wires not illustrated in the drawing.
• the above-described device can feed yarn 17 to a textile machine for processing, to produce a knitted fabric for instance.
• the yarn (coming from a reel that is not illustrated in the drawing) passes through the adjustable yarn tensioner 5, then winds at least one turn around the roller 3 before passing through the race 13A in the pulley 13, which returns it through a yarn guide 19 to deliver it to the machine for processing.
• the lengths of yarn entering and exiting from the pulley 13 together form a very narrow angle ⁇ (e.g. approximately 7° in the example in figure 1). Using this arrangement, the tension of the yarn is unloaded onto the sensor 15 with a resultant corresponding to approximately twice its real value.
• the tension of the yarn being processed makes the rod 7 turn in the direction opposite the arrow F1 of Fig.1 , overcoming the effect of the spring 9.
• the force exerted by the spring is adjusted by the operators, who adjust the angular position of the bush 8 so that, with the required tension on the yarn, the rod 7 is positioned at a certain angle with respect to the graduated segment 12, e.g. approximately at the midline thereof.
• the control unit contained in the body 1 receives a signal from the pressure sensor 15 that is proportional to the tension on the yarn 17; it compares the signal with the required tension previously specified in its resident memory, and then it adjusts the speed of the motor driving the roller 3 so as to keep the tension of the yarn 17 close to the required value.
• the control unit accelerates the movement of the roller 3; vice versa, it makes the roller turn more slowly if said pressure tends to diminish with respect to the pre-set value.
• the rod 7 is drawn downwards, even to the point where it comes up against the arched rabbet blade 10. This movement of the rod 7 prevents any excessively rapid increases in the tension of the yarn 17, an action that is prolonged both by the rod 7 bending (thanks to its flexibility) against the rabbet 10 and by the shape of said rabbet 10.
• the device has a plate-shaped body 201 , to which a variable-speed electric motor (e.g. of the brushless, direct-current type) and a corresponding electronic control unit (not illustrated in the drawing) are attached.
• a variable-speed electric motor e.g. of the brushless, direct-current type
• a corresponding electronic control unit not illustrated in the drawing
• the device On the front of the body 201 illustrated in Fig. 7, the device has a revolving roller 203 mounted co-axially on the output shaft of the motor, that is on the opposite side of the plate 201 , a plate-type yarn tensioner 205 entirely similar to the one 5 in Fig. 1 , a rod 207 swinging around an axis X-X, and a rod-returning device 209.
• the take-up rod 207 is obliged to move clockwise (looking at Fig.
• a wheel 212 idly supported onto the end of a small rod 214, which is in turn hinged along an axis Y-Y to a saddle 216 sliding on a horizontal guide 217 and attachable thereto, in the preferred position, by means of fixing means that are not illustrated in the drawing.
• a spiral spring 220 working between the small rod 214 and the saddle 216, obliges said small rod to move clockwise so as to rest against the take-up rod 207, making the latter turn in the same direction.
• Changing the position of the saddle 216 along the guide 217 induces a variation in the point where the wheel 212 comes to rest along the rod 207, and this consequently enables an accurate adjustment of the return torque brought to bear thereon.
• the saddle 216 also has an extension 216A, which serves as a rabbet for the rod 207, restricting its downward movement due to the tugging of the yarn.
• One end of a tab 221 in the form of a thin, narrow and elongated plate, is welded onto the free end of the rod 207; the upper side of the other end of said tab is welded to a bush 221A for a stud enabling the swinging of a bracket 211 , which carries an idle pulley 213, said bracket and pulley being similar and serving the same purposes as the corresponding elements 11 and 13 of Fig. 1.
• Two strain gauges 215 are attached to the two sides of the tab 221 , which are electrically connected, forming a bridge, to the control unit (not illustrated) of the device and serving the same purpose as the sensor 15 of Fig. 1. Normally, as it moves along, the yarn 17 (Fig.
• the device according to this embodiment of the invention is extremely sensitive to the feed tension of the yarn due to the sensor with the two bridging strain gauges 215, so it facilitates the passage of the yarn onto the feed * roller 203, where it is wound only through 180°, and it also enables a precise and easy adjustment of the take-up rod 207 returning torque by means of the adjustable saddle 216.
• the drawing only shows one example, given exclusively as a practical illustration of the invention, which may vary in form and arrangement without departing from the concept underlying said invention. Any use of reference numbers in the attached claims is made exclusively to facilitate the reading of the claims with reference to the description and shall in no way restrict the scope of protection represented by the claims.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Tension Adjustment In Filamentary Materials (AREA)
• Knitting Machines (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34980382

Family Applications (1)

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Cited By (8)

Families Citing this family (10)

Citations (3)

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• 2004
  • 2004-05-14 IT IT000113A patent/ITFI20040113A1/it unknown
• 2005
  • 2005-05-12 EP EP05742675A patent/EP1751335A1/en not_active Withdrawn
  • 2005-05-12 CN CNA2005800194720A patent/CN1969071A/zh active Pending
  • 2005-05-12 US US11/569,082 patent/US20070227197A1/en not_active Abandoned
  • 2005-05-12 JP JP2007512363A patent/JP2007537369A/ja active Pending
  • 2005-05-12 WO PCT/IT2005/000273 patent/WO2005111287A1/en active Application Filing

Patent Citations (3)

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