Classifications

• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
  • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
  • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
  • D03D47/3026—Air supply systems
  • D03D47/3053—Arrangements or lay out of air supply systems
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D47/00—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms
  • D03D47/28—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed
  • D03D47/30—Looms in which bulk supply of weft does not pass through shed, e.g. shuttleless looms, gripper shuttle looms, dummy shuttle looms wherein the weft itself is projected into the shed by gas jet
  • D03D47/3026—Air supply systems
  • D03D47/3033—Controlling the air supply
• • D—TEXTILES; PAPER
  • D03—WEAVING
  • D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
  • D03D51/00—Driving, starting, or stopping arrangements; Automatic stop motions
  • D03D51/12—Driving, starting, or stopping arrangements; Automatic stop motions for adjusting speed

Definitions

• the present invention relates to a method for controlling 5 a loom, comprising a weaving machine including a shed, through which a yarn is conveyed by means of at least one main weft yarn injector, to which a pressurized medium is supplied, wherein at least the time of arrival of the yarn at the end of the shed is detected, which time is then compared with a desired time, after which, in case of a difference between the
• the yarn is conveyed from the supply drum through the shed by means of a main injector
• Various natural phenomena such as variations in the transmission of the pulse from the medium to the yarn in the main injector and variations in the friction that the yarn encounters upon its
• US patent no 4446,893 discloses a loom which comprises a detector disposed at the end of the shed, which detects the arrival times of the yarn, averages said
• the pressure of the medium supplied to the main injector is adjusted to the effect that the starting velocity for the yarn in a
• the loom disclosed in the aforesaid US patent no. 4,722,370 includes not only a detector for detecting the arrival time at the end of the shed, but also a detector which detects the velocity, or the time of arrival , at a position located at the beginning of the shed With this latter detector the yarn velocity is measured during an initial phase of the weft insertion already, and if said velocity is different from the desired velocity, the supply of medium to the main injector is adjusted to such an extent that the velocity is adjusted during the weft insertion already, in such a manner that the yarn end will arrive at the desired point in time
• the yarn end will indeed reach the end of the shed at a desired point in time, but the velocity at which the yarn end reaches the end of the shed may be entirely different, or even be much higher than desirable.
• the object of the invention is to provide a method for controlling a loom, wherein the yarn arrives at the end of the shed at a desired reproducible point in time and at a low velocity
• the method according to the invention is characterized in that the ideal time of arrival of the yarn end at the end of the shed is determined on the basis of the number of revolutions of the loom, after which upon commencement of the weaving process the ideal medium pulse that is transmitted to the yarn via the main injector during the initial phase of the weft insertion is determined in such a manner that the yarn end will reach the end of the shed at a specified ideal velocity at the aforesaid ideal point in time; wherein detection of the ideal arrival times associated with a number of positions in the shed takes place at said positions, from which an ideal position-time diagram for the yarn being conveyed through the shed is derived; after which the time of arrival of the yarn end is detected at the aforesaid several positions with each weft insertion during the weaving process, which time is then compared with the ideal arrival
• the ideal time of arrival of the yarn end at the end of the shed is thus determined first. Said time will practically correspond to the point in time at which the loom closes the shed. At that point in time, the weft yarn must have arrived at the end of the shed. If the weft yarn arrives late, it will not extend through the entire shed yet, resulting in a weaving flaw. In itself, early arrival is not a very serious problem, but it implies that the yarn velocity upon arrival was too high.
• the ideal arrival time must practically coincide with the moment the shed closes, but in view of the inevitable, small variation in arrival times that takes place over several weft insertions, the ideal arrival time will be at a point slightly before the shed closes
• the ideal medium pulse transmitted to the yarn via the main injector during the initial phase of the weft insertion is determined in such a manner that the desired ideal arrival time in combination with an ideal low velocity is achieved with said ideal medium pulse
• said ideal medium pulse can be calculated theoretically per se
• said ideal medium pulse is according to another embodiment of the method according to the invention determined in an iterative process, wherein, starting with the highest allowable medium pulse, depending on the yarn strength, it is attempted to determine a pulse time at which the yarn, on average, arrives at the ideal point in time, after which the variation in the arrival times is determined and, if said variation is larger than desirable, the pulse height is reduced and the pulse time is extended until the yarn, on average, arrives at the ideal point in time again, after which the variation in the arrival
• an ideal medium pulse is obtained, wherein the yarn arrives at the end of the shed at the correct ideal point in time and at an ideal low velocity. Then detection of the ideal arrival times associated with a number of positions in the shed takes place at said positions, which times are subsequently recorded, from which an ideal position-time diagram for the yarn passing through the shed is derived.
• the above-described process for determining the ideal medium pulse can also be carried out in such a manner that initially a low medium pulse is used, after which, through adjustment of the height and/or the duration of the pulse, a situation is reached wherein the yarn end reaches the end of the shed at the correct time again, whilst the variation remains small.
• the arrival times measured at the aforesaid positions are compared with the previously determined ideal arrival times for said positions with each next weft insertion during the weaving process, after which, upon detection of a difference between the measured times and the ideal times, the medium pulse transmitted to the yarn in the main injector is changed in such a manner that the detected difference is eliminated.
• the detected difference can be such that the detected times are later than the ideal times. This means, therefore, that the velocity of the yarn is too low In order to correct this, the velocity of the yarn end must be increased.
• another advantageous embodiment is characterized in that the medium pulse transmitted to the medium in the main injector during an initial phase of the weft insertion is selected so that said pulse is larger than the ideal medium pulse, after which, if a difference between the measured yarn velocity and the ideal yarn velocity is detected, the medium pulse transmitted to the yarn is reduced by reducing the time during which the medium is supplied to the injector and/or by reducing the pressure at which the medium is being supplied
• the medium pulse that is initially transmitted to the yarn has a value higher than that which is associated with the ideal medium pulse
• the initial velocity of the yarn will be higher than the ideal velocity
• the yarn end will reach specific positions in the shed sooner than prescribed by the ideal position-time diagram This difference will be detected by the sensors, after which the medium pulse that is being supplied to the injector will be reduced As a result
• the points in time at which the yarn end reaches specific positions in the shed can be detected, for example by means of sensors which are disposed in the shed Furthermore it is possible to detect specific measured yarn lengths that pass already before the yarn enters the injector, and to derive therefrom the current position of the yarn
• the loom comprises a yarn preparing device with a supply drum on which a number of windings can be wound and from which said windings can be unwound again in order to be supplied to the loom
• ttns manner it is still possible without using sensors disposed in the shed to accurately determin p the point in time at which the yarn end has arrived at a specific position in the shed
• the loom and the method
• Figure 1 schematically shows a loom according to the invention.
• Figure 2 shows an example of a position-time diagram in accordance with which a yarn is conveyed through the shed of a loom
• numeral 1 schematically indicates the shed of a loom
• numeral 2 indicates a main injector, to one side of which a weft yarn 3 is supplied, whilst a pressurized medium can be supplied to another side of said main injector via line 4.
• Weft yarn 3 is unwound from a drum 5 of a yarn-preparing device, onto which a number of windings 6 can be wound
• a winding meter 7 is furthermore present on drum 5, which winding meter detects the windings as they leave drum 5
• a brake device 8 (schematically indicated) is provided for braking the yarn when the yarn reaches the final part of the shed Winding meter 7 is connected, via a signal line 9. to an electronic device 10, to which the winding meter 7 feeds a signal representative of the time at which the windings 5 leave the drum
• Supply line 4 for the supply of a medium to the main injector 2 is connected, via suitable lines, to valves 11 and 12. and possibly to a number of further valves 13, 14, etc Valves 11 - 14 are in turn connected to reduction valves 11 ' - 140 which connect to a main supply line 15 for supplying a pressurized medium.
• At least one of the valves 11 - 14 will be open during operation of the device, at least during an initial phase of the weft insertion, and supply a pressurized medium to main injector 4, as a result of which yarn 3 will be pulled off the drum 5 and be conveyed through the shed 1
• the windings that are being unwound from drum 5 are thereby detected by winding meter 7, which transmits a signal 9 representative of the time each winding leaves the drum to the electronic device 10
• Each winding that is unwound represents a specific yarn length, so that the position in the shed of the leading end of the yarn is known each time a winding is being unwound.
• a medium under high pressure is fed into main pressure line 15 by means not shown
• Said medium is supplied to valves 11 and 12 via reduction valves 11 ' and 120 wherein a specific pressure PI is adjusted in valve 11 and a lower pressure P2 is adjusted in valve 12.
• the ideal point in time at which the yarn end is to arrive at the end of the shed 1 is first determined in a preparatory phase Ideally, said point in time coincides with the point in time at which the shed closes Said point in time is indicated by numeral 8 in Figure 2
• a medium pulse is supplied to injector 2 by means of valves 11 - 14, as a result of which a weft yarn is supplied to the shed and detection of the time at which the yarn end has reached the end of the shed takes place If said time is different from the ideal time 8, the medium pulse will be varied by means of valves 11 - 14.
• the ideal position-time diagram the full line in Figure 2
• the ideal times at which the yarn must have reached positions 1 - 8 can be determined
• the times at which the yarn end has reached said positions 1 - 8 during a weft insertion are can be compared with the ideal times as represented by the points on the ideal
• the times at which the yarn end has reached the various positions are obtained from winding meter 7 Said windinq meter counts the successive windings and also detects the time at which each winding is unwound
• Each winding that leaves the drum represents a specific yarn length, so that the exact location of the front yarn end in the shed is exactly known, for example at position 1 after the first winding at position 2 after the second winding etc Since also the time at which each winding is unwound is recorded, said unwinding times also correspond to arrival time at position 1 2 etc
• These data are supplied, via signal line 9 to electronic device 10 which registers said data and which compares the current times of arrival at locations 1, 2 etc to the ideal times of arrival that follow from the ideal position-time diagram of Figure 2
• a medium pulse is supplied to injector 2 via valve 11, which pulse is larger than the medium pulse that is required for supplying a yarn at the ideal velocity
• the starting velocity of the yarn will be too high, as a consequence of which the yarn will follow line 8'' in Figure 2, at least during the initial phase Depending on the control method.
• the medium pulse to injector 2 is reduced, either by closing valve 11 sooner or by reducing the pressure of the medium being supplied, for example by closing valve 11 and opening valve 12 at a lower pressure
• the yarn velocity is reduced and said velocity will no longer follow line 8 0 but line 8, which is the ideal line
• a comparison between the current arrival times and the ideal times can be made at several positions or at all positions, and in case of a difference the supply of medium to the injector can be adjusted directly In this manner it is ensured that the yarn will arrive at the end of the shed in accordance with the ideal position-time diagram and at the correct time at all times Not only will the time of arrival be the same at all times, but also the velocity upon arrival will be ideally low, taking into account small differences, of course, which can always occur due to natural causes

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Looms (AREA)

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• 2000
  • 2000-03-02 NL NL1014537A patent/NL1014537C2/nl not_active IP Right Cessation
• 2001
  • 2001-02-09 EP EP01910230A patent/EP1259667B1/de not_active Expired - Lifetime
  • 2001-02-09 AU AU2001237808A patent/AU2001237808A1/en not_active Abandoned
  • 2001-02-09 CN CN 01805816 patent/CN1261631C/zh not_active Expired - Fee Related
  • 2001-02-09 DE DE60107210T patent/DE60107210T2/de not_active Expired - Fee Related
  • 2001-02-09 WO PCT/NL2001/000111 patent/WO2001064986A1/en active IP Right Grant
  • 2001-02-09 JP JP2001563667A patent/JP2003525360A/ja active Pending

Non-Patent Citations (1)

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