US3776161A - Thread trimming device for lockstitch sewing machines - Google Patents

Thread trimming device for lockstitch sewing machines Download PDF

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Publication number
US3776161A
US3776161A US00278906A US3776161DA US3776161A US 3776161 A US3776161 A US 3776161A US 00278906 A US00278906 A US 00278906A US 3776161D A US3776161D A US 3776161DA US 3776161 A US3776161 A US 3776161A
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US
United States
Prior art keywords
thread
cam
loop taker
arm
cutting blade
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
US00278906A
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English (en)
Inventor
R Papajewski
J Kleinschmidt
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SSMC Inc
Original Assignee
Singer Werke GmbH
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Publication of US3776161A publication Critical patent/US3776161A/en
Assigned to SSMC INC., A CORP. OF DE reassignment SSMC INC., A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SINGER COMPANY, THE
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Expired - Lifetime legal-status Critical Current

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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

Definitions

  • ABSTRACT A thread trimming device for a lockstitch sewing ma- [21] Appl' 278906 chine in which a thread pull-off arm, a thread catching arm, and a thread cutting blade are swung at different 52 US. Cl. 112/252 distances back a forth transversely of the face of a 51 Int. Cl D05b 65/02 leekstiteh forming p taker y a novel armngernent [58] Field of Search 112/252 of earn means on the ng machine whereby the r trimmer elements may move across the paths of prom- 5 R f r it inences of the loop taker but without interference with the loop taker.
  • a sequence of movements of the'variouselements-of the thread trimming mechanismto avoid physicalinterference with movement of the loop taker prominences is attained in this invention by a novelarrangement of a plurality of trimmer actuating cams and a mechanism for responding in sequence to the actuating cams.
  • This invention provides a thread trimming: mechanism which occupies a minimum of space in the vicinity of the'loop taker and which can be readily applied to any one of a wide variety oflockstitch'sewing machine constructions.
  • FIG. 3 is a side elevational view mer actuating cam of FIG. 2,
  • FIG. 4 is an enlarged cross-sectional view taken substantially along line 4--4 of FIG. 1 showing both the primary and secondary thread trimmer actuating cams together with the respective cam followers,
  • FIG. 5 is a perspective view of the thread engaging elements of the thread trimming mechanism
  • FIG. 6 is an enlarged cross-sectional 'view of the sewing machine bed taken substantially along linc 66of FIG. 1 showing the inoperative position of'the thread trimmer elements
  • FIG. 7- is a view of the thread trimmer elements similar to that shown in FIG. 6 but showing the first'movement of the thread catching and thread pull-off armsin response to the primary actuating cam,
  • FIG. MS a view of the thread trimming elements similar to that shown in FIG. 7 but showing thethread cutting blade and thread pull-off arm inthe extreme positions to which they are shifted by the secondary actuating cam, and
  • FIG 9 is a view of the thread trimming elements similar to that shown in FIG. 8 but. showing the thread catch-ing arm in the thread severing position into which it is shifted by the primary actuating cam.
  • FIGS. 1 and 6 11 is a work supporting bed of a sewing machine frame.
  • a loop taker indicated generally at 12 is supported in the bed and serves to concatenate needle thread with thread issuing from .
  • a bobbin 13 held in a bobbin case 14 within the loop taker in the formation of lockstitches.
  • the loop taker may take the form of that disclosed and described in greater detail in the US. Pat. No. 2,085,699, June 29, 1937 to which reference may bebad.
  • This loop taker is referred to in the art as a rotary hook and includes 5 a needle thread seizing beak 15 which may extend from the rim 16 of a cup-shaped body within which the bobbin case 14 is constrained.
  • a peripheral thread pull-off rib 17 is attached to the hook body rim 16 in a conventional manner.
  • the thread pull-off rib l7, hook rim l6, and bobbin case 14 are each irregularly formedon the exposedface of the hook and may include axial projections which have significance in the manipulation of the threads during stitch formation.
  • a support block 22 for the movable thread influen'cingm'embers of the thread trimming mechanism of this invention.
  • Pivoted on a common fulcrum stud 23 secured in the support block 22 are a pair of bell crank levers 24 and 25.
  • a thread cutting blade 26 embraces a pin 28 projecting from one arm of the bell crank lever 24" and is secured with capacity for a limited range of adjustment about the pin 28 by a fastening screw 2).
  • the extremity of the bell crankxlever 24 is recessed as at 30 and a'clamp screw 31 threaded into the bell crank lever in this recess can 'be used to deflect the thread cutting blade-toregulate the cutting position thereof.
  • a thread catching arm 40 which is secured to one arm'of the bell crank-lever 25 by a fastening screw 41 is formed, as shown in FIGS. 5 and 6, with a flattened v heel portion42 which overlaps and can engage the bell crank 24.
  • the free extremity of the thread cutting blade 26 is formed with a sharpened cutting edge 43, and the free extremity of the thread catching arm 40 as shown'in FIG. 5, is formedwith a laterally extending thread engaging hook 44' suitable for catching and drawing threads across the cutting edge 43.
  • both the sharpened cutting edge 43 "and the thread engaging hook 44 v occupy positions radially outwardly of the loop taker 12.
  • Both of the bell crank levers 24 and 25 are provided with lever arms 24' and-25', respectively, by which the levers may be imparted shifting movements.
  • the support block 22 accommodates an eccentric end portion 49 of a pivot pin 50 preferably clamped by a setscrew 51. On the pin 50 is pivoted a thread pull-off lever 52.
  • the thread pull-off lever 52 is formed with a lateral stop arm 53 engageable with an abutment pin 54 projecting from the bell crank lever 24.
  • the thread pull-off lever 52 is also formed with a shoulder 55 engageable with the flattened heel 42 of the thread catching arm.
  • a coil spring 56 on the pivot pin 50 has one extremity anchored on the support block 22 and is formed at the other extremity 57 for engagement with the thread pull-off lever 52 so as to bias the pull-off lever in a counterclockwise direction as viewed in FIGS. 6, 7 and 8 against either the abutment pin 54 or the heel 42 of the thread catching arm whichever is shifted most in a clockwise direction.
  • the free extremity of the thread pull-off lever 52 is formed with a laterally offset thread engaging finger 58 as shown in FIG. which in the retracted position of the parts illustrated in FIG. 6, is located radially outward of the loop taker 12.
  • the actuating mechanism for shifting the elements of the thread trimming mechanism in such a way that interference with the loop taker is avoided, will now be described.
  • the actuating mechanism of the sewing machine includes a shaft 60 journaled in the bed 11 and connected as by means of a timing belt 61 with other actuating mechanism in the sewing machine.
  • a hook shaft 63 to which the loop taker 12 is secured is driven preferably at a speed of two revolutions for each revolution of the bed shaft 60.
  • a first cam 70 which is secured by a set screw 71 to the bed shaft, is shown in FIGS. 2 and 3.
  • the first cam includes a hub 72 from which projects a cam lobe 73 which extends only approximately 180 about the bed shaft.
  • the periphery of the cam. lobe is formed with cam surfaces 74 and 75 disposed at different distances radially from the bed shaft axis.
  • Also extending from the hub 72 is a radial arm 76 terminating in a follower throw-out plow 77 which may be arranged diametrically opposite to the cam lobe 73.
  • a second cam 80 formed with a hub 81 is similarly secured to the bed shaft 60 by a set screw 82 and includes a cam lobe 83 which extends only approximately 180 about the bed shaft 60.
  • the cam lobe 83 of the second cam is formed to extend at a constant distance radially from the bed shaft axis. It will be appreciated that the peripheries of both the first and second cam lobes may be varied to suit the requirements of any particular loop taker for which it is desired to adapt this trimmer v
  • both the first and second cams 70 and 80 are shown to indicate the relative ar-- rangement on the bed shaft 60.
  • the follower 90 for the first cam 70 is formed at the extremity of a rock arm 91 secured by a split clamp 92 to a rock shaft 93 which is axially shiftable as well as 93 is connected to an electric solenoid 95 which when energized draws the follower 90 into the path of the cam lobe 73 of the first cam.
  • a light return spring 96 urges the follower into retracted position, but this spring is preferably so small that while the cam lobe 73 is effective, the friction prevents the spring 96 from acting.
  • the plow 77 will retract the follower and the spring serves primarily to prevent accidental shift of the follower toward the first cam.
  • An elongate crank pin 97 on the rock shaft 93 provides a connection with a link 98 which will not separate on axial movement of the rock shaft.
  • the link 98 is pivoted in turn to a rock arm 99.clamped on a rock shaft 100 which extends forwardly in the sewing machine bed 11 through the web 20 where a rock arm 10] is secured thereon.
  • the rock shaft 100 extends in telescopic fashion through a rock sleeve 109 journaled in the web 20.
  • a follower arm 110 for the second cam 80 is secured to the rock sleeve at one side of the web 20 and a rock arm 111 is .secured to the rock sleeve adjacent to the rock arm 101.
  • a connecting link 115 is provided between a pivot pin 116 in the rock arm 111 and a pivot pin 117 in the lever arm 24' of the bell crank 24 to which the thread cutting blade 26 is secured.
  • Aconnecting link 120 is also provided between a pivot pin 121 in the rock arm 101 and a pivot pin 122 in the lever arm 25' of the bell crank 25 to which the thread catching arm 40 is secured.
  • the connecting link 120 is formed with an extension 123. beyond the pivot pin 122 to which extension is secured a coil spring which is attached to an anchor pin 131 located on the rock arm 111 between the sleeve 109 and the pivot pin 116.
  • the solenoid 95 draws the follower 90 for the first cam 70 into the path of the cam 70 when the follower 90 occupies a position beyond the approximate occupied by the cam lobe 73.
  • the follower 90 will be shifted radially outward by the cam surface 74 of the cam lobe 73 causing the thread picking arm 40 tomove radially inwardly across the path of the loop taker pull-off rib carrying with it the thread engaging finger 58 of the 'thread pull-ofi' lever 52 into the position shown in FIG.
  • the increased radius segment 75 of the first cam 70 causes an additional increment of movement of the thread catching arm 40 to insure pick up of both the bobbin and needle thread limbs to be severed. It will be appreciated that the location and shape of these cam surfaces may be chosen to impart these movements of the parts to the extent and at such times as will avoid interference with the operating parts of the loop taker.
  • said thread trimming mechanism comprising a plurality of thread influencing members each separately supported for movement transversely of the face of said circularly moving loop taker, a plurality of different cam means carried by said sewing machine, a separate cam follower means cooperating with each of said cam means, operative connections between each of said cam follower means and different ones of said plurality of members of said thread trimming mechanism, and drive means operated by said actuating mechanism for moving said cam means relatively to each of said separate cam follower means at a different time during the circular movement of said loop taker so as to move said different ones of said plurality of members of said thread trimming mechanism transversely of the face of said circularly moving loop 45 I taker at different times during the'circular movement of saidloop taker.
  • a thread trimming mechanism as set forth in claim 1 in which said thread influencing members of said thread trimming mechanism include a thread catching arm and a thread cutting blade, and in which said cam means includes a first cam, linkage operatively connecting the cam follower associated with said first cam with said thread catching arm, a second cam, and linkage operatively connecting the cam follower associated with said second cam with said cutting blade and in which said drive means is arranged to move said first cam into cooperative relation with thecam follower associated with the thread catching arm before said second cam is moved into cooperative relation with the cam follower associated with said cutting blade.
  • both said first and second cam means comprise cam discs formed with peripheral cam surfaces and in which spring means is provided for biasing said thread catching arm and said thread cutting blade into retracted positions remote from said loop taker, the cam follower associated with said first cam means being positioned by said linkage closer to the axis of said first cam than the maximum radius of said peripheral cam surface thereof when said thread catching arm occupies said retracted position, the cam follower associated with said second cam means being located by the linkage in a position at a greater distance from the axis of said second cam means than the maximum radius of said peripheral cam surface thereof when said thread cutting blade occupies said retracted position, means for selectively shifting said cam follower into tracking relation with said first cam means, and spring means extending between said thread catching arm and said thread cutting blade and effective to shift said cam follower into tracking relation with said second cam means after said thread catching arm is shifted by said first cam means.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Sewing Machines And Sewing (AREA)
US00278906A 1972-08-09 1972-08-09 Thread trimming device for lockstitch sewing machines Expired - Lifetime US3776161A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US27890672A 1972-08-09 1972-08-09

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US3776161A true US3776161A (en) 1973-12-04

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US (1) US3776161A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
JP (1) JPS5547495Y2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE2338473C2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
FR (1) FR2195980A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1379214A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
IT (1) IT992777B (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3867892A (en) * 1974-05-09 1975-02-25 Singer Co Underbed thread trimmer for chainstitch sewing machines
US3921554A (en) * 1973-05-30 1975-11-25 Aisin Seiki Thread-trimming device on a sewing machine
US3935827A (en) * 1974-07-22 1976-02-03 Union Special Corporation Thread cutter mechanism for sewing machines
US3970020A (en) * 1973-04-27 1976-07-20 Necchi S.P.A. Sewing threads trimming device for sewing machines
US4077342A (en) * 1975-12-15 1978-03-07 Union Special Corporation Thread trimming mechanism for sewing machines
US4098208A (en) * 1976-07-17 1978-07-04 Pfaff Industriemaschinen Gmbh Sewing machine having a device for initiating the movement of the thread catcher of a thread cutting device
DE2719610A1 (de) 1977-03-21 1978-09-28 Singer Co Programmierbare naehmaschine zum automatischen naehen
DE2719534A1 (de) 1977-03-21 1978-10-12 Singer Co Mit programmierbarer variabler geschwindigkeit betreibbare naehmaschine
DE2719541A1 (de) 1977-03-21 1978-10-12 Singer Co Programmierbare naehmaschine
US4138958A (en) * 1978-03-02 1979-02-13 The Singer Company Thread trimmer driving mechanism for sewing machines
US4141307A (en) * 1976-09-24 1979-02-27 Aisin Seiki Kabushiki Kaisha Thread cutting mechanism for sewing machines
US4181088A (en) * 1978-03-30 1980-01-01 The Singer Company Underbed thread trimmer for sewing machines
US4187792A (en) * 1978-03-27 1980-02-12 Union Special Corporation Thread trimmer
US4235179A (en) * 1979-07-19 1980-11-25 The Singer Company Underbed thread trimmer picking arm
US4256048A (en) * 1979-10-09 1981-03-17 Amf Incorporated Knife mechanism for twin needle sewing apparatus
US4365568A (en) * 1980-05-15 1982-12-28 The Singer Company Underbed thread trimmer and controlled single-operation cam mechanism therefor
US4455957A (en) * 1981-06-24 1984-06-26 Pfaff Industriemaschinen Gmbh Thread cutter for a zig-zag 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
US20100175602A1 (en) * 2009-01-09 2010-07-15 Zeng Hsing Industrial Co., Ltd. Thread cutting device for a sewing machine

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10055258C1 (de) * 2000-11-08 2002-03-07 Viking Sewing Machines Ab Husk Fadenabschneider

Citations (5)

* 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
US3443540A (en) * 1966-02-25 1969-05-13 Kochs Adler Ag Thread trimming device for lockstitch sewing machine
US3512491A (en) * 1967-09-27 1970-05-19 Kochs Adler Ag Thread cutting mechanism for lockstitch sewing machines
US3605664A (en) * 1969-05-13 1971-09-20 Pfaff Ag G M Thread cutting mechanism for lock-stitch sewing machines with oscillating looptaker

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1660916C3 (de) * 1967-09-27 1975-05-28 Kochs Adler Ag, 4800 Bielefeld Fadenabschneideeinrichtung für Nähmaschinen
DE1941681A1 (de) * 1969-08-16 1971-06-09 Pfaff Ag G M Fadenschneideinrichtung an Doppelsteppstichnaehmaschinen

Patent Citations (5)

* 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
US3141432A (en) * 1962-04-26 1964-07-21 Pfaff Ag G M Thread-trimming mechanism for sewing machines
US3443540A (en) * 1966-02-25 1969-05-13 Kochs Adler Ag Thread trimming device for lockstitch sewing machine
US3512491A (en) * 1967-09-27 1970-05-19 Kochs Adler Ag Thread cutting mechanism for lockstitch sewing machines
US3605664A (en) * 1969-05-13 1971-09-20 Pfaff Ag G M Thread cutting mechanism for lock-stitch sewing machines with oscillating looptaker

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970020A (en) * 1973-04-27 1976-07-20 Necchi S.P.A. Sewing threads trimming device for sewing machines
US3921554A (en) * 1973-05-30 1975-11-25 Aisin Seiki Thread-trimming device on a sewing machine
US3867892A (en) * 1974-05-09 1975-02-25 Singer Co Underbed thread trimmer for chainstitch sewing machines
US3935827A (en) * 1974-07-22 1976-02-03 Union Special Corporation Thread cutter mechanism for sewing machines
US4077342A (en) * 1975-12-15 1978-03-07 Union Special Corporation Thread trimming mechanism for sewing machines
US4098208A (en) * 1976-07-17 1978-07-04 Pfaff Industriemaschinen Gmbh Sewing machine having a device for initiating the movement of the thread catcher of a thread cutting device
US4141307A (en) * 1976-09-24 1979-02-27 Aisin Seiki Kabushiki Kaisha Thread cutting mechanism for sewing machines
DE2719534A1 (de) 1977-03-21 1978-10-12 Singer Co Mit programmierbarer variabler geschwindigkeit betreibbare naehmaschine
DE2719541A1 (de) 1977-03-21 1978-10-12 Singer Co Programmierbare naehmaschine
DE2719610A1 (de) 1977-03-21 1978-09-28 Singer Co Programmierbare naehmaschine zum automatischen naehen
US4138958A (en) * 1978-03-02 1979-02-13 The Singer Company Thread trimmer driving mechanism for sewing machines
US4187792A (en) * 1978-03-27 1980-02-12 Union Special Corporation Thread trimmer
US4181088A (en) * 1978-03-30 1980-01-01 The Singer Company Underbed thread trimmer for sewing machines
US4235179A (en) * 1979-07-19 1980-11-25 The Singer Company Underbed thread trimmer picking arm
US4256048A (en) * 1979-10-09 1981-03-17 Amf Incorporated Knife mechanism for twin needle sewing apparatus
US4365568A (en) * 1980-05-15 1982-12-28 The Singer Company Underbed thread trimmer and controlled single-operation cam mechanism therefor
US4455957A (en) * 1981-06-24 1984-06-26 Pfaff Industriemaschinen Gmbh Thread cutter for a zig-zag 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
US20100175602A1 (en) * 2009-01-09 2010-07-15 Zeng Hsing Industrial Co., Ltd. Thread cutting device for a sewing machine
US8069799B2 (en) * 2009-01-09 2011-12-06 Zeng Hsing Industrial Co., Ltd. Thread cutting device for a sewing machine

Also Published As

Publication number Publication date
JPS4958561U (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1974-05-23
GB1379214A (en) 1975-01-02
DE2338473A1 (de) 1974-02-21
JPS5547495Y2 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1980-11-07
DE2338473C2 (de) 1984-08-02
IT992777B (it) 1975-09-30
FR2195980A5 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1974-03-08

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Legal Events

Date Code Title Description
AS Assignment

Owner name: SSMC INC., A CORP. OF DE, CONNECTICUT

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:SINGER COMPANY, THE;REEL/FRAME:005041/0077

Effective date: 19881202