US3710743A - Thread-cutting mechanism for sewing machines - Google Patents

Thread-cutting mechanism for sewing machines Download PDF

Info

Publication number
US3710743A
US3710743A US00197681A US3710743DA US3710743A US 3710743 A US3710743 A US 3710743A US 00197681 A US00197681 A US 00197681A US 3710743D A US3710743D A US 3710743DA US 3710743 A US3710743 A US 3710743A
Authority
US
United States
Prior art keywords
thread
cutting
work
passageway
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
US00197681A
Other languages
English (en)
Inventor
N Lees
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.)
SSMC Inc
Original Assignee
Singer Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Singer Co filed Critical Singer Co
Application granted granted Critical
Publication of US3710743A publication Critical patent/US3710743A/en
Assigned to SSMC INC., A CORP. OF DE reassignment SSMC INC., A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: SINGER COMPANY, THE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • D05D—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES D05B AND D05C, RELATING TO SEWING, EMBROIDERING AND TUFTING
    • D05D2207/00—Use of special elements
    • D05D2207/02—Pneumatic or hydraulic devices
    • D05D2207/04—Suction or blowing devices

Definitions

  • ABSTRACT A thread-cutting mechanism for a sewing machine 1' which employs a stream of air to carry the threads to the cutter and to remove the severed threads, and which is arranged periodically to interrupt the flow of air while the work feeding mechanism of the sewing machine is effective to cause variations in the air pressure in the thread-cutting device to facilitate move ment of threads into the cutter without interfering with the transport ofthe work by the work'feeding mechanism.
  • Thread severing mechanisms have been known heretofore to utilize a vacuum or flow of air caused by application of a suction to cause the threads which are desired to be severed to be drawn into position for influence by the cutter as well as to carry away the severed pieces of thread.
  • a problem which arises with the known thread cutters using suction or air flow to move the thread, is that pockets of relatively calm air flow or backwash can form in which the thread or severed thread pieces can stagnate. This can lead to clogging of the cutter and it could result in accumulations of thread building up in the thread cutter which could clog the mechanism when such accumulations suddenly are caught up in the air stream.
  • Cutters are also known which utilize a vacuum or flow of air which is varied but not in relationship to the effective stroke of the work feeding mechanism of the machine.
  • These known thread cutting mechanisms have the disadvantage that the transport of the work through the sewing machine can be disrupted by the thread cutter, particularly where light work fabrics are being sewn.
  • This object of the invention is attained by an arrangement in the thread-cutting mechanism of a thread inlet chamber and a thread outlet chamber to which air suction means communicates.
  • the thread severing mechanism includes a vibrating thread'cutting blade arranged alternately to open and close the passageway between the air inlet and air outlet compartments in response to a drive mechanism operated in timed relation with the sewing machine work feeding mechanism.
  • FIG. 1 is an end elevational view partly in vertical cross-section of an overedge sewing machine having the thread cutting device of this invention applied thereto, a
  • FIG. 2 is an exploded perspective view of the threadcutting device of this invention
  • FIG. 3 is a top plan view of the thread-cutting device with the top cover of the thread outlet chamber partly broken away to expose the mechanism therein, and
  • FIG. 4 is a cross sectional view taken substantially along line 4-4 of FIG. 3.
  • the sewing machine of this invention is applied to an overedge sewing machine of the type which is described in detail in the U.S. Pat. No. 2,238,796, Apr. 15, 1941, to which reference may be had.
  • This sewing machine includes a frame 11 which carries a work supporting cloth plate 12.
  • a top cover or hood 13 on the machine frame houses operating mechanism including a needle carrier 14 to which a curved needle 15 is secured forforming stitches on a work-fabric which is arranged on the cloth plate 12.
  • a work feed dog 16 operates upwardly through the cloth plate to transport work fabrics being stitched from left to right as viewed in FIG. 1.
  • the feed dog is opposed by a presser foot 17 carried by a presser lever 18 sustained by the machine frame.
  • a work trimmer lever 19 is fulcrummed on a pin 20 in the machine frame and operatively connected to a driving pitman 21 which is operated by the main shaft 22 by way of an eccentric v 23 secured to the main shaft by a key 24, with the eccentric being embraced by the pitman 21.
  • a work guard 25 may be secured to the top cover 13 to protect the work fabrics being stitched from the operating mechanism.
  • the feed dog 16 is secured as by a fastening screw 26 to a feed bar 27 which straddles a slide block 28 which embraces a feed lift eccentric 29 secured on the sewing machine main shaft 22.
  • the feed dog is elevated into engagement with the work fabric during the feed stroke of the feed dog and the eccentrics 23 and 29 are preferably arranged to raise and lower the work trimming lever and feed dog simultaneously so that the work will be trimmed only while it is stationary between work feeding strokes of the feed dog.
  • the thread cutting device is indicated in the drawings generally at 30 and is best shown in FIG. 2.
  • the thread trimming device comprises a body member 31 which is generally U-shaped with spaced arms 32 and 33 joined by a base portion 34.
  • the spaced arms 32 and 33 are formed with aligned bores 35 and 36 which accommodate bushings 37 in which is journalled a thread cutter shaft 38 formed with a noncircular key section 39.
  • a collar 40 is secured on the cutter shaft by means ofa set screw 41 for constraining a bowed spring 42 against a thread cutting knife 43.
  • the knife is formed with a noncircular aperture 44 which embraces the noncircular key section 39 of the thread cutter shaft to lock the knife on the shaft.
  • the knife is formed with a radial notch 45 to accommodate the bowed spring 42 and is also formed with a thread-cutting edge 46.
  • the thread cutter shaft carries a cutter operating rock arm 48 having a hub 49 which is secured to the cutter shaft by a set screw 50.
  • the cutter operating rock arm 48 is formed with a radial slot 51 which embraces a slide block 52 journalled on a pivot pin 53 carried by the driving pitman 21 and serves to impart oscillation to the thread-cutting knife 43 when the sewing machine is operated.
  • the arm 33 of the U-shaped body member 31 is formed with a thread inlet chamber which is open toward the inside of said arm and is formed with a thread inlet opening 61 at the top.
  • a sheet metal enclosure 64 which is secured by a fastening screw 65 to the other arm 32 of the body member, is accommodated in a recessed seat 66 in the body member and provides a thread outlet chamber 67.
  • the thread outlet chamber is closed at the top by a cover plate 68 which includes a gasket 69 and is secured to the body member by a fastening screw 70.
  • Secured to the enclosure 64 is a conduit 71 which opens into the thread outlet chamber 67 and may be directed to any suitable source of negative air pressure so as to apply a substantially constant negative air pressure or suction to the thread outlet chamber 67.
  • the body member 31 may be formed with a mounting lug 75 having holes 76 for any suitable fastening devices.
  • the sheet metal enclosure 64 may be formed with an opening for the mounting lug 75 and a gasket 78 may be provided for the purpose of sealing this opening in substantially airtight condition.
  • Various other mounting facilities for securing the threadcutting attachment to the sewing machine may be provided such as a mounting lug 79 extending rearwardly from the body member 31.
  • a passageway 80 is provided-between the thread inlet and thread outlet chambers 60 and 67, respectively, on the inside of the arm 33.
  • the passageway 80 is bordered by a ledger blade 81 arranged at the top of the passageway 80 and secured by a fastening screw 82 to the body member arm 33.
  • the ledger blade is formed with a cutting edge 83 adapted to cooperate with the cutting edge 46 of the thread-cutting knife 43.
  • the passageway 80 is bordered at the sides and bottom by a spacer plate 84 (FIG. 4), preferably of the same thickness as the ledger blade and secured to the body member arm 83 by screws 85.
  • the thread-cutting knife 43 will be oscillated during periodsof operation of the sewing machine so as to move between the extreme positions illustrated in'the solid and dotted line positions shown in FIG. 4, causing the opposing cutting edges 46 and 83 of the knife and ledger blades to cooperate in scissors fashion to sever any thread which may extend through the passageway 80.
  • the oscillation of the threadcutting knife will alternately open and close the passageway 80 as shown in FIG. 4, thereby causing the source of negative air pressure or suction to which the conduit 71 is connected to apply a varying negative pressure in both the thread outlet compartment 67 and in the thread inlet compartment 60.
  • the effect of a fluctuating negative pressure in the thread inlet chamber 60 will be to encourage the introduction therein of thread extending from the stitch forming instrumentalities in the sewing machine as represented by the needle 15.
  • the rush of air therethrough will carry such threads across both of the scissors type edges 46 and 83.
  • the fluctuations in air pressure in the airoutlet chamber 67 will encourage movement of the severed thread ends through the conduit 71 and to a thread end collecting means (not shown) which may be of anyknown type.
  • the eccentric 23 for operating the thread cutter and the eccentric 29 for lifting the feed dog are synchronized to lift their respective members at the same time, the flow of air through the thread-cutting device will be interrupted during the work feeding stroke of the work feed dog. As a result, the threadcutting device will not draw work fabrics toward or into the thread inlet opening 61 during transport of the work fabric and the thread cutter will, therefore, not interfere with transport of the work fabrics.
  • a mechanism for cutting the sewing threads of a sewing machine having a thread carrying stitch-forming mechanism, work feeding mechanism effective intermittently to transport work fabric relatively to said stitch-forming mechanism, and actuating mechanism for operating said stitch-forming and work feeding mechanisms in timed relation to form a line of stitches
  • said thread-cutting mechanism comprising a housing formed with an inlet chamber having a thread inlet opening disposed in the line of stitch formation, and a substantially airtight outlet chamber, a conduit connecting said outlet chamber with a source of negative air pressure, and a passageway extending between said air inlet chamber and said outlet chamber, a threadcutting blade shiftably supported in said housing for severing movement in a path alternately opening and closing said passageway to provide for pulsation in the air pressure existent in both said air inlet and said outlet chambers for encouraging movement of threads therein, and drive mechanism for said thread-cutting blade operated by said sewing machine actuating mechanism and effectiveto shift said thread-cutting blade into 'a position closing said passageway.
  • a thread-cutting mechanism as set forth in claim 1 in which said work feeding mechanism includes a work feed dog and said actuating mechanism includes a feed lift eccentric for intermittently raising said' feed dog into an effective work transporting position, and 'in which said driving means for said thread-cutting blade comprises an eccentric driven in synchronism with said feed lift eccentric.
  • a thread-cutting mechanism as set forth in claim 1 in which said passageway between said air inlet and outlet chambers is bounded by a ledger blade formed with a thread-cutting edge and by a spacer plate, said ledger blade and spacer plate having substantially coplanar outer surfaces against which said t hread-cutting blade is supported for oscillatory movement.
  • a thread-cutting member as set forth in claim 1 in which said housing includes a U-shaped body member formed in the spaced apart arms, said outlet chamber encompassing the space between said arms, and said passageway being formed' in one of said arms, said thread-cutting blade being supported between said arms and biased against a ledger blade secured to said body member area inwhich said passageway is formed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Sewing Machines And Sewing (AREA)
US00197681A 1971-06-27 1971-11-11 Thread-cutting mechanism for sewing machines Expired - Lifetime US3710743A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3516571A GB1361858A (en) 1971-06-27 1971-06-27 Thread-cutting mechanism for sewing machines

Publications (1)

Publication Number Publication Date
US3710743A true US3710743A (en) 1973-01-16

Family

ID=10374599

Family Applications (1)

Application Number Title Priority Date Filing Date
US00197681A Expired - Lifetime US3710743A (en) 1971-06-27 1971-11-11 Thread-cutting mechanism for sewing machines

Country Status (3)

Country Link
US (1) US3710743A (it)
GB (1) GB1361858A (it)
IT (1) IT956961B (it)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54135267U (it) * 1978-03-11 1979-09-19
EP0342555A1 (de) * 1988-05-17 1989-11-23 Schips Ag Nähautomation Nähmaschine mit selbsttätiger Nähgutstück-Trennung
WO2009144049A1 (en) * 2008-05-30 2009-12-03 Lonati S.P.A. Sewing or looping head, particularly for automated closing of tubular knitted articles at an axial end thereof
CN110359192A (zh) * 2019-07-09 2019-10-22 杰克缝纫机股份有限公司 缝纫机剪线装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3058438A (en) * 1960-12-19 1962-10-16 Frank D De Long Jr Cutting mechanism
US3149594A (en) * 1960-09-22 1964-09-22 Frank D De Long Jr Method and apparatus for trimming stitches
US3182620A (en) * 1963-09-03 1965-05-11 Wm G Leininger Knitting Co Surplus thread removing apparatus
US3242892A (en) * 1964-08-11 1966-03-29 Doctor E Fowler Sewing machine cutter
US3554149A (en) * 1968-10-21 1971-01-12 Trim Master Corp Thread-cutting attachment for sewing machines
US3624734A (en) * 1969-04-02 1971-11-30 Helmut Schips Thread-cutting device on sewing machines

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3149594A (en) * 1960-09-22 1964-09-22 Frank D De Long Jr Method and apparatus for trimming stitches
US3058438A (en) * 1960-12-19 1962-10-16 Frank D De Long Jr Cutting mechanism
US3182620A (en) * 1963-09-03 1965-05-11 Wm G Leininger Knitting Co Surplus thread removing apparatus
US3242892A (en) * 1964-08-11 1966-03-29 Doctor E Fowler Sewing machine cutter
US3554149A (en) * 1968-10-21 1971-01-12 Trim Master Corp Thread-cutting attachment for sewing machines
US3624734A (en) * 1969-04-02 1971-11-30 Helmut Schips Thread-cutting device on sewing machines

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54135267U (it) * 1978-03-11 1979-09-19
EP0342555A1 (de) * 1988-05-17 1989-11-23 Schips Ag Nähautomation Nähmaschine mit selbsttätiger Nähgutstück-Trennung
US5027733A (en) * 1988-05-17 1991-07-02 Schips Ag Nahautomation Sewing machine with automatic separation of pieces of sewing material
WO2009144049A1 (en) * 2008-05-30 2009-12-03 Lonati S.P.A. Sewing or looping head, particularly for automated closing of tubular knitted articles at an axial end thereof
US20110073028A1 (en) * 2008-05-30 2011-03-31 Lonati S.P.A. Sewing or Looping Head, Particularly for Automated Closing of Tubular Knitted Articles at an Axial End Thereof
US8631751B2 (en) 2008-05-30 2014-01-21 Lonati S.P.A. Sewing or looping head, particularly for automated closing of tubular knitted articles at an axial end thereof
CN110359192A (zh) * 2019-07-09 2019-10-22 杰克缝纫机股份有限公司 缝纫机剪线装置
CN110359192B (zh) * 2019-07-09 2021-03-16 杰克缝纫机股份有限公司 缝纫机剪线装置

Also Published As

Publication number Publication date
IT956961B (it) 1973-10-10
GB1361858A (en) 1974-07-30

Similar Documents

Publication Publication Date Title
GB691894A (en) Improvements in overedge sewing machines
GB1280070A (en) Improvements in or relating to sewing machines
US3710743A (en) Thread-cutting mechanism for sewing machines
US2298246A (en) Machine for attaching articles
US3922983A (en) Device for automatic cutting of thread in sewing machines
US3116706A (en) Attachment for overedging
US2893336A (en) Sewing machine
US3109399A (en) Sewing machine thread cutting mechanism
GB687812A (en) Improvements in needle feed sewing machines
US2973731A (en) Compound stitching device
US2136288A (en) Throat plate for sewing machines
US3962980A (en) Thread cutter for sewing machines
US2372318A (en) Thread severing device for sewing machines
US3465702A (en) Method and apparatus for treating cloth-end threads in a sewing machine
US1387012A (en) Strip-severing device for sewing-machines
US3065716A (en) Design stitching sewing machine
US3494315A (en) Thread cutting mechanism for sewing machines
US1177138A (en) Seam-trimmer for sewing-machines.
US263650A (en) Stockton borton
US2070029A (en) Thread-cutter for sewing machines
US1361247A (en) Thread-controlling mechanism for sewing-machines
US255578A (en) And charles
US381536A (en) dewees
US2277970A (en) Sewing machine
US387029A (en) Chaeles h

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