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

• the finding relates to a feeder device for textile machines such as circular or straight knitting machines, hosiery machines and the like, in particular for machines in which the needle bed can also operate in reciprocating motion.
• the present invention relates to an improved feeder/take-up device comprising - in succession according to the path of the yarn - a yarn brake, a motorized roller around which the yarn is drawn to feed it to the textile machine, and a yarn take-up rod pivoted at one end thereof and provided at the other end with a yarn guide, said yarn guide which may be a simple eyelet
• the device comprises: a torque sensor that reads the torque value transmitted by the yarn tension to the take-up rod; an angular sensor that reads the angular position of the rod; a microprocessor electronic control unit that receives pulses from said torque and angular position sensors and, on the basis of a stored control program, drives the motor of the yarn drawing roller according to an algorithm which, with a predetermined frequency, determines the value of an electric supply voltage of the motor as a function of said torque transmitted by the yarn and of said angular position of the rod so as to tend to eliminate the difference between said torque read and a predetermined torque value corresponding to desired operating tension of the yarn, and to tend to reduce the angular deviation of the rod from a neutral position, to maintain the reserve of yarn supplied by the take-up rod constant.
• the device according to the invention can also comprise a damper to dampen oscillations of the rod, further improving the precision of response.
• said torque sensor is an extensometric sensor attached to a flexible plate.
• This plate has a first end fastened to a rotating supporting element of the take-up rod, said rotating element being pivoted to the fixed structure of the feeder device, while the second end of the plate is free to move bending the plate, with travel limited by specific stops inside said rotating element.
• Fastened to the second end of the plate is an end element which has a hole through which the stem of the take-up rod is made to pass, so that the angular accelerations of the rod in one or other direction are transmitted to said end element causing bending of the plate and a corresponding variation of the signal transmitted by the sensor to said control unit.
• said angular position sensor of the take-up rod can, for example, be an encoder with a toothed disk integral with said rotating supporting element of the take-up rod and a pair of LEDs, emitter and receiver respectively, positioned to detect the passage of the teeth of the disk with rotation of the rotating element together with the take-up rod.
• the control program stored in the electronic control unit can comprise a series of instructions repeated cyclically with a predetermined frequency, i.e. every 0.5 ms, and which provides for in succession: reading of the predetermined values, set by an operator and stored in the unit, of the torque (Co) transmitted by the yarn to the take- up rod at the required predetermined operating tension of the yarn, and of the desired neutral angular position ( ⁇ 0 ) of the rod; reading of the current torque (C) and angle ( ⁇ ) values transmitted by the respective sensors; calculation of the deviations between said current values (C 1 ⁇ ) and said predetermined values (C 0 , ⁇ 0 ); - calculation of the acceleration to be given to the motor by means of a table of correspondence between the current values (C, ⁇ ) and the torque to be delivered by the motor according to a predetermined law; variation of the motor power supply to obtain said acceleration value; - return to the start of the sequence of instructions for repetition thereof.
• a predetermined frequency i.e. every 0.5 ms
• Said predetermined law can be represented by means of a table of correspondence - obtained previously by means of practical tests - from which the program extracts the values, or by means of a mathematical algorithm which, for example, can be of the type represented by the following formula:
• V electrical supply voltage of the motor
• Vmax maximum allowable supply voltage of the motor
• K c ( ⁇ ) A a + B, wherein A, B are constants
• Ka(C) D-C + E, wherein D and E are constants.
• ⁇ (C) C- C 0
• the drawing means of the take-up rod comprise an electro-mechanic actuator, for example a small electric motor, and driving means thereof to load the take-up rod by a torque opposing to that one generated by the yarn supplied by the device.
• Torque provided by said actuator is controlled by the microprocessor electronic control unit of the device based on the angular position and the motion state of the take-up rod read by an angular encoder, in order to aim to take back the rod in a central position of its possible angular stroke.
• Said electric motor may also provide the function of the extensometric sensor mentioned above, namely the torque sensor function.
• the torque characteristic of the motor versus its driving voltage or the wave shape of the voltage itself should be store in a memory of the electronic control unit, and the software executed by the control unit should be implemented to adapt the that motor driving voltage according to a prefixed torque, i.e. to a prefixed yarn tension.
• Figure 1 shows a schematic side view of a device according to the invention
• Figure 2 shows an enlarged cross sectional elevation according to H-Il in Figure 1;
• Figure 2 shows a cross sectional plan view according to Ill-Ill in Figure
• Figure 4 shows a cross sectional elevation according to IV-IV in Figure 3
• Figure 5 shows a partial cross sectional elevation according to V-V in Figure 2;
• Figure 6 shows a flow diagram of the control program of the device
• Figure 7 shows a view of another embodiment of the invention similar to that of Figure 1 ;
• Figure 8 show a partial sectional view according VIII-VIII of Figure 7, and
• Figure 9 show a partial sectional view according IX-IX of Figure 8.
• a yam feeder/take-up device has a fixed structure with a plate 1 and comprises - in succession according to the yarn path - a yarn brake 2, of the classic type with plates 1 , a motorized roller 3 around which the yarn 5 is drawn to feed it to the textile machine in the direction of the arrow F, and a yarn take-up rod 7 pivoted according to a horizontal axis X-X in the manner to be described below.
• the take-up rod 7 is provided at the free end thereof with a yarn guide eyelet 9 and is attached at the other end to a rotating element 11 pivoted to the fixed structure of the device.
• the rotating element 11 and consequently also the rod 7, is angularly stressed in a clockwise direction (looking at Figure 1) by a pair of tension springs 13 (see also Figure 5), said springs being attached at one end to a pin 15 ( Figure 2) of an adjustment ratchet 17, and at the other end to a pin 19 fastened to a pair of arms 11A of the rotating element 11.
• the adjustment ratchet 17 is mounted rotatingly with radial clearance on the plate 1 , can be rotated by means of a knob 21 and has external teeth 17A that engage in a desired angular position, under the action of said springs 13, in a pin 23 projecting inwardly from the plate 1. In this way, it is possible to adjust the tension of the springs 13, to balance the take-up rod in a desired angular position when it is under the action of the desired tension of the yarn-.
• the device also comprises: a torque sensor 25 ( Figures 2, 3, 4), which reads the torque value transmitted by the tension of the yarn to the take-up rod 7; an angular sensor 27 ( Figures 2 and 3), which reads the angular position of the rod 7; a microprocessor electronic control unit which receives pulses from said torque 25 and angular position 27 sensors and, on the basis of a stored control program, drives the motor of the yarn drawing roller 3 ( Figure 1).
• the control program acts according to an algorithm which, with a predetermined frequency, determines the value of the electrical supply voltage V of the motor as a function of the torque transmitted by the yarn and of the angular position of the rod, imposing an acceleration or deceleration on the roller 3 so as to tend to eliminate the difference between said torque read and a predetermined torque value corresponding to the desired operating tension of the yarn, and to tend to reduce the angular deviation of the rod from a predetermined neutral position, so as to maintain the reserve of yarn supplied by the take-up yarn constant.
• Said control program stored in the electronic control unit comprises a series of instructions repeated cyclically with a predetermined frequency, for example every 0.5 ms, and which provides for in succession ( Figure 6): a step 101 to perform reading of the predetermined values - stored in this unit in a preceding step 100 - of the torque C 0 transmitted by the yarn to the take-up rod at the required predetermined operating tension of the yarn, and of the desired neutral angular position ⁇ 0 of the rod; a step 102 to read the current torque C and angle ⁇ values transmitted by the respective sensors 25, 27 and to calculate the deviations between said predetermined values C 0 , ⁇ 0 and said current values C, ⁇ ; a step 103 to calculate, by means of a dedicated algorithm, the acceleration to be given to the motor; a step 104 to vary the power supply of the motor to obtain said acceleration value; after this step, the cycle of instructions continues, returning to the start of the sequence, i.e. step 101 , and the sequence is repeated every 0.5 ms.
• V current electrical supply voltage of the motor
• V ma x maximum allowable supply voltage of the motor
• K c ( ⁇ ) A a + B, wherein A, B are constants
• the acceleration value of the motor is varied every 0.5 ms to accelerate or decelerate yarn delivery and consequently adjust both the tension of the yarn and the angular position of the take-up rod 7 to cause these parameters to take preset values.
• the device also comprises a liquid crystal display and keys for entering the parameters, not shown in the drawing.
• the torque sensor 25 ( Figures 3 and 4) is an extensometric sensor attached to a flexible plate 25A a first end 25B of which is fastened to the rotating supporting element 11 of the take-up rod 7.
• the second end 25C of the plate is fastened to an end element 31 which has a hole 31 A through which the stem of the take-up rod 7 is made to pass with minimum or no clearance.
• the end element, and consequently also the end 25C of the plate 25, is limited in the relative movement thereof with respect to the rotating element
• the angular sensor 27 of the take-up rod 7 ( Figures 2 and 3) is an encoder with a toothed disk 27A integral with said rotating supporting element 11 of the take-up rod 7 and a pair of LEDs, emitter 27B ( Figure 2) and receiver 27C ( Figure 2) respectively, positioned to detect passage of the teeth of the disk 27A with rotation of the rotating element 11 together with the take-up rod 7.
• the device also comprises a damper 29 to dampen oscillations of the rod 7 formed of a hollow cylinder 29A pivoted to a pin 33 fastened to the structure 1 of the feeder device, and of a piston 29B movable in the cylinder 29A and pivoted to an arm 11 B (see also Figures 3 and 5) of said rotating element 11 that carries the take-up rod 7.
• a device comprises a yarn brake 2 (Fig. 7), a motorized roller 3 around which the yarn 5 is drawn to be fed to a textile machine, a yarn take-up rod 7 pivoted at one end around an X-X axis and provided with a yarn guide eyelet 9 at the other end thereof, an encoder 27 and a torque sensor 25 disposed according the first embodiment already described to measure the angular excursions and the torque applied to the rod 7 around said X-X axis.
• the rod 7 is angularly loaded by yarn drawing means that include an electric actuator 100 for applying the rod 7 a torque opposing to that generated by the yarn.
• said actuator 100 is an electric motor comprising:
• stator 102 having electric coils 106 and fixed to the plate 1 of the body of the yarn feeder/take-up device, and - a rotor 104 fixed to the rotating shaft 11 of the rod 7.
• the device also comprises a microprocessor electronic unit that receives signals from said torque sensor 25 and from said angular sensor 27; based on a stored control software, this electronic unit controls the motor of the yarn drawing roller 3 in the same way described for the first embodiment of the invention; moreover - based on the rod angular position and the motion state read by the encoder 27 - the same electronic unit (via a suitable driving unit) drives the actuator 100 to recall the rod to a central position of its allowable angular excursion providing the rod a torque having a preset value previously input to the electronic unit by an operator.
• a microprocessor electronic unit that receives signals from said torque sensor 25 and from said angular sensor 27; based on a stored control software, this electronic unit controls the motor of the yarn drawing roller 3 in the same way described for the first embodiment of the invention; moreover - based on the rod angular position and the motion state read by the encoder 27 - the same electronic unit (via a suitable driving unit) drives the actuator 100 to recall the rod to a central
• the extensometric sensor 25 of the torque loading the rod can be omitted, the electric motor 100 being able to accomplish its function with the assistance of said electronic control unit and its software.
• the motor torque characteristic versus its voltage driving value or wave shape should be stored in a memory of the electronic unit, and the software thereof should be implemented to adjust said driving voltage according to a prefixed torque value corresponding to the required yarn tension.

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

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Publications (1)

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Family Applications (1)

Country Status (2)

Cited By (4)

Citations (3)

• 2006
  • 2006-12-22 IT ITFI20060335 patent/ITFI20060335A1/it unknown
• 2007
  • 2007-12-17 WO PCT/IT2007/000874 patent/WO2008078351A1/en active Application Filing

Patent Citations (3)

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