US3921554A - Thread-trimming device on a sewing machine - Google Patents

Thread-trimming device on a sewing machine Download PDF

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Publication number
US3921554A
US3921554A US474462A US47446274A US3921554A US 3921554 A US3921554 A US 3921554A US 474462 A US474462 A US 474462A US 47446274 A US47446274 A US 47446274A US 3921554 A US3921554 A US 3921554A
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United States
Prior art keywords
thread
shaft
blade means
partial gear
machine
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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
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US474462A
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English (en)
Inventor
Seizo Uozaki
Hitoshi Sakashita
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.)
Aisin Corp
Original Assignee
Aisin Seiki Co Ltd
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Publication date
Application filed by Aisin Seiki Co Ltd filed Critical Aisin Seiki Co Ltd
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Publication of US3921554A publication Critical patent/US3921554A/en
Anticipated expiration legal-status Critical
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    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B65/00—Devices for severing the needle or lower thread
    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B57/00—Loop takers, e.g. loopers
    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B73/00—Casings
    • D05B73/04—Lower casings
    • D05B73/12—Slides; Needle plates

Definitions

  • This invention relates generally to industrial straight lock stitch sewing machines. More specifically, it relates to improvements in and relating to threads trimming device.
  • An object of the present invention is to provide the threads trimming device workable at the best operating phase and at the closest possible position to the conventional rotary hook.
  • a further object of the invention is to provide the threads trimming device of the above kind, adapted for positive prevention of the blowing-out of the upper thread before the catching thereof for the trimming job.
  • FIG. 1 is an inverted plan view of essential parts of the thread-cutting device according to the present invention from the bottom side of the machine bed.
  • FIG. 2 is a perspective view of the essential parts of the thread-cutting device according to the invention.
  • FIG. 3 is a front elevation of the thread-cutting device when seen from the front side of the machine bed which is shown in chaindotted line.
  • FIG. 4 is a perspective view of a tension release mechanism cooperating with the threadcutting device.
  • FIG. 5 is a partial sectional elevation of a needle bar together with a part of the machine arm, specifically illustrating a timing mark provided on the needle bar.
  • FIG. 6 is an enlarged detail side view of a pair of partial gears employed in the thread-cutting device shown at a timing in coincidence of that of the needle bar shown in FIG. 5.
  • FIG. 7 is a partial sectional front view of a thread catcher included and cooperating with a conventional rotary hook, the scale being slightly enlarged from that of FIG. 3 and the timing being such that the thread catcher begins to catch the sewing thread.
  • FIG. 8 is a similar view to FIG. 6, wherein, however, the timing is same as in FIG. 7.
  • FIG. 9 is a similar view to FIG. 7, wherein, however, the thread catcher has caught the sewing yarn.
  • FIG. 10 is a similar view to FIG. 6, wherein, however, the timing corresponds to that employed in FIG. 9.
  • FIG. 11 is a similar view to FIG. 7, wherein, however, the timing is such that the thread cutter has just cut the thread.
  • FIG. 12 is a similar view to FIG. 6, wherein, however the timing corresponds to that employed in FIG. 11.
  • numeral 1 denotes schematically and partly in phantom manner a machine bed, a mounting frame 2 being fixedly attached on a lower surface of said bed by means of set screws 3 and 4.
  • a shaft 6 having an operating rigid lever portion 5 is mounted rotatably on the frame 2 at 2a and 2b.
  • the shaft 6 is further provided rigidly with an enlarged flange 7 attached thereto by means of a set screw 8.
  • the shaft 6 is formed with a shoulder 9 for 2 the prevention of occasional axial shift of the shaft, said flange 7 serving for the same purpose.
  • a coil spring 10 is mounted on and between a part of said frame and radial projection 7a of said flange 7.
  • said radial projection 7a is kept in engagement with a stationary stop 11 as shown in FIGS. 1 and 2, said stop being fixedly positioned by being threaded through a portion of said frame.
  • Numeral 12 represents a partial gear toothed only at and mounted loosely on said shaft 6.
  • This partial gear is formed with an axially projecting boss 12a which is formed in turn with an axial slot 14 slidably receiving an axial projection 13 projecting rigidly from said flange 7.
  • Partial gear 12 is slidable axially on the shaft 6, but its rotation is made in unison therewith, by virtue of the fixed mounting of the flange 7 on the shaft.
  • Arm member 15 is mounted loosely on the shaft 6, said member 15 being formed with a recess 16 kept normally in engagement with the tip end of a plunger 19 of thread-cutter solenoid 18 which is fixedly mounted on a part of said frame 2 by means of a plurality of set screw 17. Therefore, the arm member 15 can not rotate normally integral with the shaft 6, even if the latter is caused to rotate.
  • solenoid 18 when solenoid 18 is energized by supply of electric current from a current source, not shown, thereto for the execution of a thread-cutting job, plunger 19 is caused to advance leftwards in FIG. 1, so as to push the partial gear 12 and flange 7 in the same direction against the action of a coil spring 20 provided between the last mentioned two members.
  • Numeral 22 represents a thread-release cable passing through a small hole formed through one end of said arm member 15 and fixedly attached thereto by a pair of fixing elements 23 and 23.
  • a flexible cable sheath 102 slidably guides the cable 22 and is attached fixedly at its one end to a stationary member 103 by means of a clip 104, said member 103 being rigid with the solenoid 18.
  • Numeral 24 represents only partially a conventional hook shaft which is supported rotatably at its one end shown by a bearing 25 press fit in position into the bed 1
  • a pivotable holder 26 is provided in close proximity of the left end of the bearing metal, FIG. 1, but it is pre vented from its axial movement by virtue of the provision of stop spring 27.
  • the holder 26 and the lever portion 5 are pivotably connected with each other by a link member 28 and stepped screws 29 and 31).
  • a stationary cutter blade 32 and a thread guide plate 33 are fixedly attached to the bed 1 by means of a set screw 31.
  • the cutter blade 32 is arranged in opposition to a thread catcher 35 which is fixedly attached to the holder 26 by a set screw 34., in such a way that the cutting edge 41 formed on the cutter blade and that at 40 formed on thread catch 35 can be brought into a shearing relationship for performing a thread-cutting job, as will be described later more fully.
  • thread guide plate 33 has an arc-shape in its side view, said arc being designed and arranged concentrically with a conventional rotary hook 36.
  • This thread guide plate 33 is arranged to occupy an intermediate position when seen in the radial direction of the rotary hook, as most clearly seen from FIG. 7.
  • the plate 33 is further provided with an opening 97 adapted for passage of the sewing thread so as to keep the part of the latter in coincidence with the center of the needle.
  • the thread catcher 35 comprises as its effective portion an arc-shaped portion made concentric to the ro' tary hook and is formed with a pointed and portion 37 followed reversedly by a thread-engaging portion 38 which is further followed reversedly by a londitudinally grooved portion 39 terminating into a cutting edge 40.
  • This movable cutting edge 40 is adapted for cooperating with a cutting edge 41 formed on the tip end of stationary cutting element 32 for performing a thread-cutting job, as will be more fully described hereinafter.
  • Hook shaft 24 is attached fixedly with a driving partial gear 42 by means of a set screw 43, said partial gear representing drive teeth at 98, as shown in FIGS. 6, 8, l and 12.
  • the partial gear 42 represents on its outer periphery a cam portion 92 having a gradually increasing radius of curvature.
  • the partial gear 42 represents a blank peripheral surface 99 terminating at said teeth 98.
  • the driving partial gear 42 having the aforementioned structure will rotate only in idle and in unison with the hook shaft 24 during the normal sewing operation of the machine. However, when the solenoid 18 is energized for initiating a thread-cutting job, the partial gear 12 is caused to slide in the aforementioned way so that the latter is brought into lateral registration with the companion partial gear 42 adapted for engagement with each other during the rotational movement of hook shaft 24.
  • tension-release lever 45 and a pivotable member 46 are pivotably mounted on the conventional machine arm 44 by means of a common pivot pin 47, although the set position has been omitted from the drawing.
  • tension release lever 45 is formed with a cam surface 48 which is adapted for acting upon a pin or tension stud 49 with rotation of said lever, so as to release the tension of the upper thread at the tension disc unit 50 of the known structure, as in the commonly known way.
  • the cable 22 slidable in and along the sheath 102 has its one end fixedly attached to the upper or motion-receiving end of the tension release lever 45 as shown in FIG. 4.
  • the rotatable member 46 When the commonly known lifting plate 52 is lifted by means of knee lifter, as an example, the rotatable member 46 is caused to rotate for pushing a pointed projection of thread tension release lever 45, so as to release upper thread tension, and indeed, by virtue of the fork joint between pin 53 and fork 54 of the rotatable member 46.
  • conventional needle bar 94 carrying a needle and reciprocated by a crank mechanism, not shown, by the rotation of a conventional upper or arm shaft, not shown, is given a timing mark shown at 95, being selected at a predetermined position on the needle bar.
  • the mark 95 is brought into coincidence with the lower end of needle bar metal 96 as shown, the needle bar will occupy a position of about 55 degrees in advance of the upper dead point of the needle bar 94.
  • the thread tension disc unit 50 is mounted on the front side of the machine arm in close proximity of the free end extremity of the latter as commonly employed, although not specifically shown.
  • the foot-operated pedal in this case, is released from its operating position, a clutch is disengaged from the main drive electric motor and a brake is applied to the shafting system including, as known, the upper shaft, not shown, for driving the needle bar 94, and the hook shaft 24, for stopping the rotation of these shaft.
  • the needle bar 94 is brought into and held just at its lower dead point by actuation of a needle position-sensing and a source-curre interruption means, not shown, which are known per se.
  • an electric speed slow-down means not shown, is operated as known per se, and the upper and the lower or hook shaft are caused to rotate at a respective slower constant speed which is selected to l/30 of the higher sewing speed.
  • the needle bar 94 moves upwards from its lower to upper dead point.
  • a known sensor is brought into operation and the trimming solenoid 18 is energized, thereby its plunger 19 being operated to push the arm member 15 and partial gear 12 axially in the aforementioned way for bringing the partial gear 12 into registration with its companion partial gear 42 ready for mutual engagement.
  • the upper thread N is subjected to a upwardly directing drawing action by the conventional thread take-up lever, not shown. But, in this case, the upper thread is held by the thread catcher 35 by being engaged thereby, so as to leave a proper end length of the thread, enough for avoiding a slip-out of the thread from the thread eyelet, not shown, of needle 94a replaceably attached to needle bar 94, at the commencement of the next sewing job.
  • the lower thread B together with a part of the upper thread which lies close to the sewing material, not shown, runs in and along the groove 39 upon leaving from the thread catcher 35, thus being prevented from cutting by contact with the cutting edge 41 of stationary knife 32. Therefore, a proper length of the lower thread as necessary for later use upon thread-trimming and reinitiation of a new sewing job can be drawn out from the bobbin case 91 and preserved in position.
  • the thread-trimming device is kept ineffective and ready for the next trimming operation, even if the sewing machine by caused to run for its regular and renewed sewing job.
  • the upper thread N drawn-in by rotary hook 36 will be urged to disengage from the latter as a result of the upward pull exerted upon the thread by the thread takeup lever, not shown.
  • the upper thread may sometimes reep up substantially in the peripheral direction of the hook 36 and could be held far from the pointed projection of the catcher 35 which is now trying to catch the thread.
  • the upper thread could not be subjected to the necessary trimming job at and between the cutting edges of the stationary and moving cutter knife elements. Or even if trimmed, a shorter length of thread end only could be preserved.
  • the trimmed end of the lower thread B is limited by the same opening 97 from its free movement, the upper thread N can pick up necessarily the lower thread B at the commencement of the next regular sewing operation.
  • a thread-trimming device for an industrial sewing machine comprising:
  • first ratchet means disposed upon said first shaft and rotatable therewith;
  • second ratchet means disposed upon said second shaft and being axially movable relative thereto so as to selectively engage said first ratchet means
  • a thread-trimming device for an industrial sewing machine wherein said first ratchet means comprises a first partial gear having teeth on only a portion of the periphery thereof and a cam surface successively disposed from said toothed gear portion; and said second ratchet means comprises a second partial gear having teeth on only a portion of the periphery thereof, whereby upon actuation of said electrically operated means, the toothed portions of said first and second partial gears are engaged with each other to rapidly rotate said movable blade means to an operable position relative to said stationary blade means and thereafter, said cam surface of said first partial gear portion comes into sliding contact with said second partial gear to slowly rotate said second blade means to cooperate with said first blade means to thereby perform the thread trimming operation.
  • a thread trimming device according to claim 2, wherein said movable blade means comprises:
  • a thread trimming device wherein said stationary blade means include a thread guide plate secured to said framework of said machine, said guide plate having a thread guiding hole through which pass upper and lower threads for assuring said thread trimming operation and the commencement of the following regular sewing operation.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Sewing Machines And Sewing (AREA)
US474462A 1973-05-30 1974-05-29 Thread-trimming device on a sewing machine Expired - Lifetime US3921554A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP6137673A JPS5643758B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1973-05-30 1973-05-30

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US3921554A true US3921554A (en) 1975-11-25

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US474462A Expired - Lifetime US3921554A (en) 1973-05-30 1974-05-29 Thread-trimming device on a sewing machine

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JP (1) JPS5643758B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4365568A (en) * 1980-05-15 1982-12-28 The Singer Company Underbed thread trimmer and controlled single-operation cam mechanism therefor
US4437423A (en) 1981-02-26 1984-03-20 Aisin Seiki Kabushiki Kaisha Thread trimming device for a sewing machine
US4757774A (en) * 1980-12-05 1988-07-19 Kochs Adler Ag Needle guide in a sewing machine
US5009177A (en) * 1988-10-21 1991-04-23 Ssmc Inc. Thread cutting unit having a rotatably driveable cutting knife and loop spreading plate for a sewing machine
US5027731A (en) * 1988-04-11 1991-07-02 Ssmc Inc. Thread cutting knife device in a sewing machine

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57135201U (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) * 1981-02-20 1982-08-23
CN110453392B (zh) * 2019-09-15 2024-10-29 浙江速普机电有限公司 一种剪线抬压脚一体装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3141432A (en) * 1962-04-26 1964-07-21 Pfaff Ag G M Thread-trimming mechanism for sewing machines
US3173392A (en) * 1961-08-11 1965-03-16 Pfaff Ag G M Thread trimming mechanism for lock stitch sewing machines
US3173393A (en) * 1961-12-13 1965-03-16 Pfaff Ag G M Thread cutting mechanism for lockstitch sewing machines
US3371633A (en) * 1965-04-07 1968-03-05 Pfaff Ag G M Thread cutting device for sewing machines
US3443540A (en) * 1966-02-25 1969-05-13 Kochs Adler Ag Thread trimming device for lockstitch sewing machine
US3756177A (en) * 1970-12-17 1973-09-04 Kochs Adler Ag Thread cutting device for double stitch sewing machines
US3776161A (en) * 1972-08-09 1973-12-04 Singer Werke Gmbh Thread trimming device for lockstitch sewing machines

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173392A (en) * 1961-08-11 1965-03-16 Pfaff Ag G M Thread trimming mechanism for lock stitch sewing machines
US3173393A (en) * 1961-12-13 1965-03-16 Pfaff Ag G M Thread cutting mechanism for lockstitch sewing machines
US3141432A (en) * 1962-04-26 1964-07-21 Pfaff Ag G M Thread-trimming mechanism for sewing machines
US3371633A (en) * 1965-04-07 1968-03-05 Pfaff Ag G M Thread cutting device for sewing machines
US3443540A (en) * 1966-02-25 1969-05-13 Kochs Adler Ag Thread trimming device for lockstitch sewing machine
US3756177A (en) * 1970-12-17 1973-09-04 Kochs Adler Ag Thread cutting device for double stitch sewing machines
US3776161A (en) * 1972-08-09 1973-12-04 Singer Werke Gmbh Thread trimming device for lockstitch sewing machines

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4365568A (en) * 1980-05-15 1982-12-28 The Singer Company Underbed thread trimmer and controlled single-operation cam mechanism therefor
US4757774A (en) * 1980-12-05 1988-07-19 Kochs Adler Ag Needle guide in a sewing machine
US4437423A (en) 1981-02-26 1984-03-20 Aisin Seiki Kabushiki Kaisha Thread trimming device for a sewing machine
US5027731A (en) * 1988-04-11 1991-07-02 Ssmc Inc. Thread cutting knife device in a sewing machine
US5009177A (en) * 1988-10-21 1991-04-23 Ssmc Inc. Thread cutting unit having a rotatably driveable cutting knife and loop spreading plate for a sewing machine

Also Published As

Publication number Publication date
JPS5643758B2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1981-10-14
JPS508656A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1975-01-29

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