EP0424395B1 - Fadenwächter - Google Patents

Fadenwächter Download PDF

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Publication number
EP0424395B1
EP0424395B1 EP89905082A EP89905082A EP0424395B1 EP 0424395 B1 EP0424395 B1 EP 0424395B1 EP 89905082 A EP89905082 A EP 89905082A EP 89905082 A EP89905082 A EP 89905082A EP 0424395 B1 EP0424395 B1 EP 0424395B1
Authority
EP
European Patent Office
Prior art keywords
thread
monitor according
stitch
sensor units
sensor unit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP89905082A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0424395A1 (de
Inventor
Kurt Arnold
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
GM Pfaff AG
Original Assignee
GM Pfaff AG
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Filing date
Publication date
Application filed by GM Pfaff AG filed Critical GM Pfaff AG
Publication of EP0424395A1 publication Critical patent/EP0424395A1/de
Application granted granted Critical
Publication of EP0424395B1 publication Critical patent/EP0424395B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B51/00—Applications of needle-thread guards; Thread-break detectors
    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B1/00—General types of sewing apparatus or machines without mechanism for lateral movement of the needle or the work or both

Definitions

  • the invention relates to a thread monitor according to the preamble of claim 1.
  • the needle thread is generally monitored between the endless thread supply and the needle.
  • the hook thread is monitored between the endless thread supply and the hook in multi-thread chainstitch sewing machines, and between the hook and the stitch formation point in double lockstitch sewing machines. After a thread fault occurs, the thread monitor emits a signal that triggers a reaction from the machine.
  • a thread monitor for monitoring the needle thread is described in German utility model 69 13 073.
  • a disc which is set in rotation by the needle thread withdrawn from the thread supply and is interrupted in the edge region by radially extending slots, is monitored by a sensor device. As soon as one of the slots is aligned with the sensor device, a pulse is passed on to an electronic switch of a control circuit. If, after the needle thread breaks, the disc stops and the electronic switch no longer receives any pulses, the sewing machine is stopped.
  • the needle thread is passed through the monitoring area of the sensor device to the needle.
  • the needle thread is alternately deflected from its central position in mutually opposite directions, so that it executes a swinging movement perpendicular to the thread pull-off direction and traverses the monitoring area of the sensor device back and forth once per stitch. Failure to do so is indicated as a fault.
  • the invention specified in claim 1 has for its object to design a thread monitor of a stitch-forming machine so that it monitors the thread along the thread path at a plurality of points and controls the machine in the event of a thread fault so that one of the fault location depending on the fault location corresponding switching process is triggered on the machine.
  • the second sensor unit for monitoring the needle thread in the thread take-off direction is provided behind the tensioning device.
  • the hook thread in multi-thread chainstitch sewing machines between the tensioning device and the hook is most at risk from thread breakage. For this reason, the area in question is also equipped with the second sensor unit.
  • the measure according to claim 2 proves to be advantageous, since smaller seam pieces can also be produced without changing the thread.
  • the measure of claim 3 is advantageous.
  • the measure according to claim 4 is applied when the processable thread length must always be constant.
  • the machine is activated according to claim 5.
  • the measure of claim 7 ensures that the thread is always monitored in areas in which it is already performed in the most appropriate manner for monitoring. Such areas are specified in claims 8 to 10.
  • Claim 11 is directed to a measure by which a sensor unit monitoring the bobbin thread of a lockstitch sewing machine can be linked to the thread monitor.
  • the thread can be monitored dynamically by the thread movement customary on sewing machines and described in the preamble of claim 12.
  • the thread When crossing the effective range of a sensor unit, the thread impulsively reduces the signal that otherwise reaches the receiver uniformly. This signal reduction is evaluated depending on the stitch formation.
  • a position transmitter monitoring the rotation of the main shaft and connected to the control device is provided, which, depending on the speed of the sewing machine, specifies the test interval in which the signal reduction must occur. A run of the test interval without a signal reduction is an indication that no thread has crossed the effective range of the sensor unit due to thread end or break.
  • Claim 13 specifies a possibility of how the sensor units for dynamic monitoring of the thread can be positioned relative to the latter. This version is also suitable for displaying skipped stitches. In this case, the transverse movements of the thread are considerably reduced because of the small thread withdrawal, so that this does not swing out of the effective range of the sensor unit. As a result, the signal reduction occurs continuously during the test interval predetermined by the position transmitter.
  • the housing (1) On the back of a multi-thread chain stitch sewing machine shown in Fig. 1, the housing (1) consists of a base plate (2) with a needle plate (3), a stand (4), an arm (5) and a head (6) , a thread supply stand (7) is arranged, on the vertical stand rod (8) of which a thread supply carrier (9) for receiving the thread supply (10) is attached. Above the thread supply (10) extends a holder (11) which is fastened to the stand rod (8) and has eyelets (12) for thread guidance.
  • a sensor unit (13) is accommodated on each eyelet (12) and is shown enlarged in FIG. 2.
  • the sensor unit (13) has a photodiode (14) as a transmitter and a photodetector (15) as a receiver.
  • the thread (F) needle or looper thread
  • the thread is in the directions shown through the area from the photodiode (14) to the photodetector (15) directional light barrier movable.
  • a sensor unit (22) (FIG. 3) is accommodated on the bracket (21), the structure of which corresponds to the sensor unit (13) with a photodiode and a photodetector.
  • the needle thread (NF) can be moved in the manner shown in the area of the sensor unit (22) perpendicular to the head (6).
  • the needle thread (FIG. 1) drawn off from the thread supply (10) is via the associated eyelet (12), via thread guides, not shown, the tensioning device (19), the thread lever (18), the bracket (21) and one on the needle bar (16) trained thread eyelet (23) fed to the needle (17).
  • the gripper (24) (FIG. 4) mounted below the throat plate (3) has on its rear side a bracket (25) attached to the base plate (2) for thread guidance.
  • a sensor unit (26) is accommodated on the bracket (25), the structure of which corresponds to the sensor units (13 and 22).
  • the looper thread (GF) swings in the area of this sensor unit (26) perpendicular to the base plate (2).
  • the looper thread drawn from the thread supply (10) (FIG. 1) passes through the associated eyelet (12), a tensioning device (27) arranged on the stand (4), a plurality of thread guides and not shown reaches the gripper (24) via the bracket (25).
  • the sensor units (13, 22 and 26) together form a thread monitor (28) and are connected to a control device (29).
  • control device (29) shows the elements required for the function of the control device (29) in a simplified circuit diagram.
  • the control device (29) enables dynamic thread monitoring.
  • Each of the two sensor units (13) has a regulated voltage source, from the positive pole of which current flows to ground via the photodiode (14) and a resistor (30). Current also flows from the positive pole of the voltage source via the photo detector (15) designed as a phototransistor and a resistor (31) to ground.
  • the emitters of the photodetectors (15) are each connected to a capacitor (32) which is used to filter out direct currents caused by daylight and alternating currents caused by low frequency sewing light.
  • the output of the capacitor (32) is connected via a negation element (33) and an amplifier (34) to an input (E1) of a counter (35). Together with the elements (32 to 34), the counter (35) forms a counting device (36).
  • a signal corresponding to the required maximum value can be fed to it via an input (E2).
  • the maximum value can be preselected on a control panel (37) to which the input (E2) is connected.
  • the maximum value preselected on the control panel (37) corresponds, for example, to one Number of stitches to be carried out by the sewing machine after a thread fault.
  • the number of stitches specifies a thread length that can be processed until the sewing machine stops, which can also take the value zero.
  • the sewing machine is designed in such a way that, for stitch numbers greater than zero, a change in the stitch length at a stitch regulator (S) which is known per se and is therefore only shown schematically causes the output of a signal assigned to the stitch length to the control panel (37).
  • the control panel (37) then automatically adjusts the number of stitches to the new stitch length so that the processable thread length is retained.
  • a position sensor (39) monitoring the revolutions of the main shaft (38) is connected to an input (E3) of the counter (35).
  • This has a photodiode (40) connected to the positive pole of a regulated voltage source, which is connected to ground via a resistor (41) and a photodetector (42) also connected to the positive pole and designed as a phototransistor, which is connected to ground via a resistor (43) is laid on.
  • a disc (44) which is fixed on the main shaft (38) and is designed with a plurality of openings (45) for the passage of the light beams. With each pass, a pulse (P) is delivered to the input (E3) of the counter (35).
  • the outputs (A) of the counters (35) are connected via an OR gate (46) to a display element (47) which is connected to ground via a resistor (48).
  • the output (A) is also with a shutdown device (49) of the drive motor (50) Sewing machine connected.
  • the drive motor (50) drives the main shaft (38) via a V-belt (51).
  • a display element (52) is connected to each of the additional inputs (ZA) of the counters (35) and is connected to ground via a resistor (53).
  • the sensor unit (22) is connected to a counting device (54) and the sensor unit (26) is connected to a counting device (55).
  • the design of the counting devices (54 and 55) corresponds to the described counting device (36), but their counters (56) have no additional output (ZA) compared to that of the counting device (36).
  • the counter devices (54 and 55) are connected via their counter outputs (A) to an OR gate (57), the output of which is connected to a display element (58).
  • the display element (58) is connected to ground via a resistor (59).
  • the shutdown device (49) of the drive motor (50) is also connected to the output of the OR gate (57).
  • the thread monitor works as follows: The cyclical succession of tensioning and relaxing the needle and the looper thread in the rhythm of the thread retraction cause these to vibrate transversely to the thread take-off direction.
  • the sensor units (13) on the thread supply stand (7) are traversed up and down by the needle and the looper thread with each stitch as long as there is no thread end or break between the thread supply (10) and the eyelets (12) is present.
  • the light signal entering the photodetector (15) of each sensor unit (13) is interrupted in each of these passes.
  • the otherwise conductive photodetector (15) is temporarily blocked and no current reaches the input of the negation element (33), so that its output outputs a signal with the potential "high”, hereinafter referred to as signal (H).
  • the signal (H) is passed on via the amplifier (34) to the input (E1) of the counter (35).
  • the counter (35) is reset by the signal (H) to its initial position, the value zero.
  • the counter (35) then begins to sum the pulses arriving at the input (E3) from the position transmitter (39), a predeterminable number of signals corresponding to one revolution of the main shaft (38). As long as both loops (12) of the thread reel stand (7) have run through threads, the counter (35) is always reset to zero before it has reached the maximum value set on the control panel (37) and entered via input (E2).
  • the relevant counter (35) counts up to the maximum value and outputs a signal (H) at its output (A) via the OR gate (46 ) to the display element (47) and to the shutdown device (49).
  • the display element (47) is switched on and the switch-off device (49) is activated such that it prevents the drive motor (50) from restarting after the next stopping process.
  • the sensor units (13) are additionally provided for the detection of missing stitches. Since only a small needle or looper thread is pulled in the event of a missing stitch, the vibration introduced in the transverse direction is very low, so that the thread in question does not leave the effective range of the assigned sensor unit (13). As a result, there is always a signal (L) at the input of the negation element (33) and a signal (H) at its output and at the input (E1) of the counter (35), which prevents the counter (35) from counting up. At the same time, the pulses from the position sensor (39) arriving at the counter input (E3) are counted in a second counter part.
  • the counting device (36) gives a signal to switch on the display element (52) at its additional output (ZA). out.
  • the light path of the sensor unit (22) is interrupted twice by the needle thread swinging back and forth perpendicular to the head (6).
  • the signals from the sensor unit (22) are transmitted to the counting device (54), in which they are evaluated in order to detect a thread break occurring behind the tensioning device (19) in the same way as the signals fed to the previously described counting device (36).
  • the counting device (54) outputs a signal (H) at its counter output (A) which, after passing through the OR gate (57), switches on the display element (58) and switches off the device (49) for immediately switching off the Drive motor (50) controls.
  • the sensor unit (26) on the bracket (25) is from the Crossing the hook thread once with each stitch going up and down.
  • the resulting brief interruption of the signal entering the photodetector (15) serves to reset the counter of the counting device (55) to the initial value zero. This resetting takes place in the manner already described for the counting device (36).
  • the bobbin thread (SF) on lockstitch sewing machines, as shown in FIG. 6, is guided along the front of the hook (60) and is deflected by it in a direction parallel to the hook axis during the rotational movement.
  • a bracket (62) for thread guidance is attached to a bearing block (61) on the underside of the throat plate (3), on which a sensor unit (63) identical in structure to the sensor units (13, 22 and 26) is received.
  • the light barrier of the sensor unit (63) runs parallel to the underside of the throat plate and perpendicular to the drawn cross-wise direction of the bobbin thread.
  • the sensor unit (63) is connected to the counting device (55) of the control device (29) instead of the sensor unit (26).
  • the bobbin thread traverses the Area of action of the sensor unit (63) swinging back and forth once per revolution of the gripper (60).
  • the interruptions in the light barrier directed towards the photodetector (15) are evaluated in the manner already described by the counting device (55).

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Sewing Machines And Sewing (AREA)
EP89905082A 1988-06-01 1989-04-28 Fadenwächter Expired - Lifetime EP0424395B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3818663A DE3818663A1 (de) 1988-06-01 1988-06-01 Fadenwaechter
DE3818663 1988-06-01

Publications (2)

Publication Number Publication Date
EP0424395A1 EP0424395A1 (de) 1991-05-02
EP0424395B1 true EP0424395B1 (de) 1992-10-21

Family

ID=6355626

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89905082A Expired - Lifetime EP0424395B1 (de) 1988-06-01 1989-04-28 Fadenwächter

Country Status (7)

Country Link
US (1) US5199365A (ja)
EP (1) EP0424395B1 (ja)
JP (1) JPH04504960A (ja)
KR (1) KR900702111A (ja)
DE (1) DE3818663A1 (ja)
ES (1) ES2014137A6 (ja)
WO (1) WO1989012124A1 (ja)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1229189B (it) * 1988-04-27 1991-07-23 Barudan Co Ltd Apparecchiatura per rilevare il filo in una macchina per cucire
US5140920A (en) * 1990-09-07 1992-08-25 The Charles Stark Draper Laboratory, Inc. Apparatus for detecting skipped stitches
US5233936A (en) * 1990-09-07 1993-08-10 The Charles Stark Draper Laboratory, Inc. Method and apparatus for detecting skipped stitches for a chainstitch sewing machine
GB9116035D0 (en) * 1991-07-25 1991-09-11 Leicester Polytechnic Detecting stitch failures in machine sewing
US5839382A (en) * 1994-09-15 1998-11-24 Tice Engineering And Sales, Inc. Electronically geared sewing machine
JP2001070682A (ja) * 1999-09-07 2001-03-21 Pegasus Sewing Mach Mfg Co Ltd ミシンの糸切れ検知装置
US6347597B1 (en) * 2000-12-27 2002-02-19 Jung Kuang Chen Flat sewing device without thread bobbins
US7308333B2 (en) * 2002-01-31 2007-12-11 Melco Industries, Inc. Computerized stitching including embroidering
US7204137B1 (en) * 2003-08-20 2007-04-17 Essex, Inc. Thread breakage detection systems and methods
JP4973010B2 (ja) * 2006-05-29 2012-07-11 ブラザー工業株式会社 電子ミシン及びミシンモータ制御プログラム
EP1882767B1 (de) * 2006-07-28 2013-07-24 BERNINA International AG Vorrichtung zur Überwachung des Oberfadens
US8020503B2 (en) * 2006-07-31 2011-09-20 Edwards Lifesciences Corporation Automated surgical implant sewing system and method
JP5064539B2 (ja) * 2009-11-13 2012-10-31 木下精密工業株式会社 縫製装置の目飛び糸切れチェック装置
US8448588B1 (en) 2011-08-18 2013-05-28 Leonard Samuel Lindley Force sensing device adapted for sensing thread tension in a long-arm or mid-arm sewing machine
JP6626715B2 (ja) * 2016-01-14 2019-12-25 Juki株式会社 ミシン

Family Cites Families (15)

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Publication number Priority date Publication date Assignee Title
DE6913073U (de) * 1969-04-01 1969-10-02 Altenburg Naehmasch Veb Fadenwaechter zur gleichzeitigen ueberwachung von spulen- und nadelfaden, insbesondere bei naehautomaten
GB826488A (en) * 1955-08-02 1960-01-06 Pfaff Ag G M Improvements in or relating to sewing machines
AT206266B (de) * 1958-05-19 1959-11-25 Josef Alge Elektrischer Fadenwächter für Stickmaschinen u. dgl.
JPS5929661Y2 (ja) * 1977-07-25 1984-08-25 アイシン精機株式会社 ミシンの駆動制御装置
DE2830534C3 (de) * 1978-07-12 1981-01-22 Pfaff Industriemaschinen Gmbh, 6750 Kaiserslautern Fadenwächter für Näh-, Stick- und Tuftingmaschinen o.dgl
US4192243A (en) * 1978-10-02 1980-03-11 Levi Strauss & Co. Sewing machine thread monitor
US4215641A (en) * 1979-07-05 1980-08-05 The Singer Company Electronic control of needle thread in a sewing machine
US4429651A (en) * 1979-08-06 1984-02-07 Tokai Kogyo Mishin Kabushiki Kaisha Device for detecting absence of a thread in a sewing machine
HU181132B (en) * 1980-05-28 1983-06-28 Csepel Muevek Jarmue Detector pin for sewing machine of short chain stitch
GB8304579D0 (en) * 1983-02-18 1983-03-23 Rawson J W Monitoring textile thread
DD228843A1 (de) * 1984-08-30 1985-10-23 Bekleidungswerke Veb Beruehrungsloser fadenwaechter fuer naehmaschinen
US4566396A (en) * 1984-09-27 1986-01-28 Tokyo Juki Industrial Co., Ltd Thread feed mechanism in sewing machine
DE3625963A1 (de) * 1986-07-31 1988-02-04 Union Special Gmbh Fadenwaechter fuer naehmaschinen
DE3800717A1 (de) * 1987-10-21 1989-05-11 Pfaff Ind Masch Naehmaschine mit einem fadenwaechter
JPH05343335A (ja) * 1992-06-09 1993-12-24 Mitsubishi Electric Corp シリコン窒化膜の形成方法

Also Published As

Publication number Publication date
KR900702111A (ko) 1990-12-05
JPH04504960A (ja) 1992-09-03
ES2014137A6 (es) 1990-06-16
WO1989012124A1 (en) 1989-12-14
US5199365A (en) 1993-04-06
DE3818663A1 (de) 1989-12-07
EP0424395A1 (de) 1991-05-02
DE3818663C2 (ja) 1991-09-19

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