US3489115A - Device for simultaneously cutting the sewing threads in a sewing machine - Google Patents

Device for simultaneously cutting the sewing threads in a sewing machine Download PDF

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Publication number
US3489115A
US3489115A US743489A US3489115DA US3489115A US 3489115 A US3489115 A US 3489115A US 743489 A US743489 A US 743489A US 3489115D A US3489115D A US 3489115DA US 3489115 A US3489115 A US 3489115A
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United States
Prior art keywords
thread
cutter
threads
clamp
counterblade
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Expired - Lifetime
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US743489A
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English (en)
Inventor
Nerino Marforio
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Virginio Rimoldi and Co SpA
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Virginio Rimoldi and Co SpA
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    • D—TEXTILES; PAPER
    • D05—SEWING; EMBROIDERING; TUFTING
    • D05B—SEWING
    • D05B65/00—Devices for severing the needle or lower thread

Definitions

  • This invention relates to a thread cutting device for cutting simultaneously the sewing threads in a sewing machine, said device comprising a shiftable cutter, a counterblade and a clamp for gripping the cut threads.
  • Thread cutting devices provided with counterblade and clamp for gripping the cut threads are known, but in all those devices the most serious inconvenience was determined by the too large distance between the area where the sewing threads are caught by the cutter and the counterblade being formed by a stationary element arranged on the machine frame.
  • the blade could not be provided near the gripping area, as other important devices of the machine were provided there, such as, i.e., the looper, the feeding device and the needle during its alternatively working movements said devices because of their struc ture occupying space useful for the provision of the counterblade and of the thread-gripping clamp.
  • the cutter should be provided so as to be able to catch the threads from the stitch-forming area and to carry them against the counterblade and in the clamp.
  • the aim of this invention is to avoid the above mentioned inconvenience, by providing a thread cutting device, which is able to cut the sewin-g threads after the latter have been gripped by the clamp.
  • the technical problem to be solved was to provide improved thread putting device in order to secure the cut of the threads after they are gripped by the clamp and whereby it can be possible to restart the sewing opreation avoiding skipstitching due to thread shortage or unthreading in the machine.
  • a thread cutting device as above mentioned has been realized, wherein the cutter, being moved by pneumatic means from a resting to a cutting position and vice versa, is connected with the counterblade and with the clamp to bring them after a short free running, near to the threads to be gripped and cut; and wherein thread pulling devices are provided, which are connected with each other and with the cutter, and which are caused to pull thread from the bobbins in order to avoid breakages of the sewing threads.
  • FIGURE 1 shows a sewing machine provided with thread cutting device
  • FIGURE 2 is an enlarged section view of the cutter and its driving means
  • FIGURES 3 and 4 are two different positions of the cutter in respect of the counterblade and the clamp;
  • FIGURES 5 and 6 are front positions of the sewing threads before and after being cut by the cutter
  • FIGURE 7 is a section view of the machine along the line VII-VII of FIGURE 1;
  • FIGURES 8 and 9 are two enlarged section views of the machine respectively along the lines VIII-VIII and IXIX of FIGURE 7.
  • FIGURE 1 shows schematically a chain stitch sewing machine in which the frame 1 comprises a base 2, a standard 3, an arm 4 integral with said standard, and a head 5 provided on the free top of the arm 4.
  • the frame 1 comprises a base 2, a standard 3, an arm 4 integral with said standard, and a head 5 provided on the free top of the arm 4.
  • the base 2 there are the known feeding means and the stitch length adjusting means and a hook '6 which cooperates with one or more needles 7 for the stitching operation.
  • the needle 7 is fixed by a suitable clam-p 8 to the usual needle bar 9 which is sliding mounted within the head 5 and is moved by usual driving means being provided within the arm 4 and not shown in the drawings.
  • a tension carrying plate 10 is provided, which tensions 11, 12 and 13 are mounted on.
  • a sliding plate 14 is interposed between the plate 10 and said tensions, the operation of which will be explained later.
  • the tensions 11 and 12 are provided to friction the needle thread in a proper way and the tension 13 is provided to friction the hook thread in a proper way.
  • the above described sewing machine is provided with a thread cutting device 15 for cutting simultaneously the sewing thread, which device is the object of this invention.
  • Said thread cutting device 15 (see FIGS. 2 to 4) is mounted on the base 2 under a needle plate 16 and is placed in front of the hook 6.
  • Said device comprises a shiftable cutter 17 interposed between two plates which are respectively a counterblade 18 for said cutter and a clamp 19 for gripping the cut threads.
  • the cutter 17, which is usually in a resting position out of the working area of the hook 6 and of the needle 7, is moved towards and from the cutting position by pneumatic means that are a plunger 20 mounted within a cylinder 21 and pushed first in one and then in the opposite direction by a pneumatic flow, flowing alternatively within the cylinder 21 and through conduits 22 and 23 which are connected with said cylinder in such a way as to result one at one part and the other one at the other part of the plunger 20.
  • Said conduits are suitably connected to each other by a suitable pneumatic plunger valve, not shown in the drawings.
  • the pneumatic valve By operating a suitable driving means, such as a treadle, the pneumatic valve supplies compressed air to the cylinder 21, at first through the conduit 22, in such a way as to move the plunger 20 towards the right, and with it to have the cutter 17 shifted into the cutting position, which is illustrated by dotted lines in FIG. 2. Afterwards, the pneumatic valve supplies compressed air to the cylinder 21 through the conduit 23, discharging the air contained in the cylinder through the conduit 22, so that the plunger 20 is brought back towards the left and the cutter 17 in the resting position. The cutter 17, during the movement to the cutting position, runs freely for a short period and after that brings both the counter-blade 18 and the clamp 19 as near as possible to the sewing threads to be gripped and cut.
  • a suitable driving means such as a treadle
  • the cutter first runs freely backwards bringing the gripped threads towards the counterblade 18 and the clamp 19, which remain in the previously reached position, in order to grip and cut the threads before beginning the movement with the cutter towards said resting position.
  • the counterblade 18 and the clamp 19 have been provided with an elongated slot 24 being as long as the free run of the cutter 17, which is provided with a pin 25 disposed throughout said cutter and having each outer end engaged in a slidable way within said slot 24,
  • the pin 25 is placed within said slots 24, placed completely to the left, having the free part of them placed at right (FIG. 3) so that the bringing of said counterblade 18 and clamp 19 can be effected only after the pin 25 has run for the entire length of the slots.
  • the free run of the cutter is necessary for disconnecting a blade 26 with which the cutter 17 is provided at its free end 27, from the counterblade 18 and the clamp 19 for gripping the sewing threads.
  • the free returning run towards the resting position is necessary for bringing up the previously caught threads on the clamp for gripping them and against the counterblade for cutting them.
  • the pin 25 is placed completely to the right, having the free part of the slots 24 placed at left (FIG. 4) so that the bringing up of said counterblade and clamp can be effected only after said pin has run for the entire length of the slots and consequently the blade 26 is already reinserted in the counterblade 18 and in the clamp 19.
  • the cutter 17 has a recess 32 which extends substantialy for the same length as the notches 28 and 29, and which is provided to prevent the cutter interfering with said leaf spring.
  • the sewing machine has been provided with a thread pulling device 37 disposed across the path of the needle thread and with a device 38 disposed across the path of the hook thread.
  • the devices 37 and 38 the first being supported by the arm 4 and the other by the base 2 of the frame 1, are provided for pulling thread from the bobbins before the thread cutting device 15 starts to function; said thread pulling devices being connected with the thread cutting device by means of the hand control of the above mentioned pneumatic valve.
  • said control is connected by a chain 39 with a lever 40 keyed on a shaft 41 mounted rotating on the standard 3 of the frame 1.
  • Said shaft 41 (see also FIG. 8) is provided to transmit the movements of the lever 40 to the sliding plate 14 and at the same time to a longitudinal shaft 42 mounted rotating within the arm 4.
  • an arm 43 On the free end of the shaft 41 is mounted an arm 43 provided with a pin 44 which has its free end engaged within a slot of the sliding plate 14.
  • the rotations of the shaft 41, being caused ,by the lever 40, are transmitted to the arm 43, which, by said pin, slides the plate 14 in respect of the tensions 11, 12 and 13 and by means of bosses 45 which said plate is provided with, the discs of said tensions are moved away each from the other; releasing the threads from the frictioning to which they are subjected.
  • an arm 46 provided on the shaft 41 transmits said rotations to another arm 47 keyed on the shaft 42 by means of a rod 48.
  • the rotations of the shaft 42 are effected in opposition to the action of a coil spring 49 having one end 50 fixed to the frame 1 and the other end 52 fixed to a ring 53 fixed to said shaftl42.
  • the shaft 42 has an articulated arm 54 hinged to an articulated lever 55 substantially disposed at and keyed on a shaft 56 which supports a thread pulling device 57.
  • the thread pulling device moves from its usual position as soon as the shaft 42 is oscillated by the lever 40, on pulling threads from the bobbins and not from the needle 7, as the tensions 11, 12 and 13 have meanwhile been opened.
  • the hook thread pulling is made in similar way by the thread pulling device 38, being directly connected with the shaft 42 by a normal wire 58 contained sliding within a suitable sheath 59.
  • another arm 60 is provided, which is connected at its free end with one end of the wire 58, the other end of which is fixed to an end 61 of a bell crank 62 of the thread pulling device.
  • Said bell crank 62 is fulcrummed in the middle on a pivot pin 63 of the base 2, and has its own other free end 64 connected with a sliding rod 65 provided with a thread guide 66.
  • the bell crank 62 oscillates about its own pivot pin in opposition to the action of check coil spring 67 pulling the thread guide 66 away from the two fixed thread guides 68 and 69 and therefore, pulling threads from the bobbins.
  • the thread pulling device 57 is provided with a thread guide being placed between two fixed guides 71 and 72.
  • the fixed thread guides are provided to avoid the threads curling or being incorrectly disposed.
  • the pneumatic valve driving means is operated by the operative, by means of the chain 39, the lever 40 is rotated and caused, as previously explained, the pulling of threads from the bobbins and only by continuing the operation on said means the pneumative valve causes the thread cutting device 15 to go into action.
  • the sewing machine is usually provided with a hand operated driving means which works independently and is not shown in the drawings, and
  • a sewing machine comprising a thread cutting device for simultaneously cutting the needle and hook threads, said device comprising a reciprocable cutter blade, a counterblade, and a clamp for gripping the cut threads, a drive means for reciprocating said cutter blade between a resting and cutting position, said cutter blade being freely reciprocable along a portion of its stroke in each of its reciprocal directions relative to said counterblade and clamp, said cutter blade driving said counterblade and clamp along the remainder of its stroke in each of said directions, a thread pulling device associated with each of the bobbins for the needle thread and the hook thread, respectively, said pulling devices being drivingly interrelated with the cutter blade and being arranged to pull thread from the respective bobbins and pursuant to said cutter blade effecting a cutting stroke on said thread whereby breakage of the thread is avoided excepting as effected by said cutter blade.
  • said counterblade and said clamp each including two notches spaced apart from each other along a surface extent thereof, the distance between notches being equal to the length of the stroke portion along which said cutter blade drives said counterblade and said clamp, a resiliently urged detent member engageable in said notches for yieldingly holding said counterblade and said clamp against movement excepting when being driven by said cutter blade during said latter part of the cutter blade stroke.
  • said drive means being a bi-directional pneumatic drive means including a pneumatic valve for determining the direction in which said drive means operates, a hand operated control means for actuating said valve, said control means being drivingly associated with said thread pulling devices whereby actuation of said pneumatic valve to cause said drive means to drive said cutter blade correspondingly drives said thread pulling devices.
  • a first of said thread pulling devices comprises a rotary shaft, an articulated arm on said shaft hingedly connected with an articulated lever which is rotatively connected with a first thread pulling lever, a second of said thread pulling devices comprising a symmetrically fulcrummed bell crank having one free end connected with a second thread pulling member, another free end of said bell crank being connected to a flexible wire means which is also connected with a radially projecting arm on said shaft, the rotational movement of said shaft being transmitted through said wire means to said second thread pulling member.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Sewing Machines And Sewing (AREA)
US743489A 1967-07-07 1968-07-08 Device for simultaneously cutting the sewing threads in a sewing machine Expired - Lifetime US3489115A (en)

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IT1813267 1967-07-07

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US3489115A true US3489115A (en) 1970-01-13

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US743489A Expired - Lifetime US3489115A (en) 1967-07-07 1968-07-08 Device for simultaneously cutting the sewing threads in a sewing machine

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US (1) US3489115A (es)
CH (1) CH468503A (es)
DE (1) DE1760703C3 (es)
ES (1) ES354872A1 (es)
FR (1) FR1571911A (es)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3602170A (en) * 1969-03-24 1971-08-31 Aisin Seiki Thread cutter in sewing machine
US3610188A (en) * 1965-02-15 1971-10-05 Reece Corp Automatic control and thread cutter for sewing machines
US3648634A (en) * 1969-11-13 1972-03-14 Dejong & Devlieger Machinehand Thread-cutting device for sewing machines
US3654883A (en) * 1970-05-14 1972-04-11 Union Special Machine Co Thread control mechanism for sewing machines
US3747548A (en) * 1971-07-14 1973-07-24 Usm Corp Thread holding and cutting
US3871307A (en) * 1973-04-05 1975-03-18 Munsingwear Inc Placket forming machine
FR2322955A1 (fr) * 1975-09-02 1977-04-01 Union Special Maschinenfab Dispositif separateur de fil pour machines a coudre a point de chainette
US4091756A (en) * 1976-03-31 1978-05-30 Union Special G.M.B.H. Pneumatically driven thread cutter
US4726305A (en) * 1986-06-19 1988-02-23 Pegasus Sewing Machine Mfg. Co., Ltd. Thread cutting device for cylinder bed sewing machine
US4984526A (en) * 1986-09-30 1991-01-15 Juki Corporation Thread chain guiding device for overedge sewing machines
US5868089A (en) * 1991-11-14 1999-02-09 The Singer Company N.V. Needle thread restraining device in a thread cutting sewing machine

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3715603C1 (de) * 1987-05-09 1988-06-23 Pfaff Ind Masch Fadenschneidvorrichtung fuer Zickzack-Naehmaschinen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707927A (en) * 1954-05-25 1955-05-10 Trimless Inc Thread cutting device for sewing machines
US3386402A (en) * 1966-07-05 1968-06-04 Singer Co Thread trimming mechanism for sewing machines
US3424117A (en) * 1965-05-08 1969-01-28 Union Special Maschinenfab Thread severing device for severing the looper and needle threads on double chain stitch sewing machines

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2707927A (en) * 1954-05-25 1955-05-10 Trimless Inc Thread cutting device for sewing machines
US3424117A (en) * 1965-05-08 1969-01-28 Union Special Maschinenfab Thread severing device for severing the looper and needle threads on double chain stitch sewing machines
US3386402A (en) * 1966-07-05 1968-06-04 Singer Co Thread trimming mechanism for sewing machines

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3610188A (en) * 1965-02-15 1971-10-05 Reece Corp Automatic control and thread cutter for sewing machines
US3602170A (en) * 1969-03-24 1971-08-31 Aisin Seiki Thread cutter in sewing machine
US3648634A (en) * 1969-11-13 1972-03-14 Dejong & Devlieger Machinehand Thread-cutting device for sewing machines
US3654883A (en) * 1970-05-14 1972-04-11 Union Special Machine Co Thread control mechanism for sewing machines
US3747548A (en) * 1971-07-14 1973-07-24 Usm Corp Thread holding and cutting
US3871307A (en) * 1973-04-05 1975-03-18 Munsingwear Inc Placket forming machine
FR2322955A1 (fr) * 1975-09-02 1977-04-01 Union Special Maschinenfab Dispositif separateur de fil pour machines a coudre a point de chainette
US4091756A (en) * 1976-03-31 1978-05-30 Union Special G.M.B.H. Pneumatically driven thread cutter
US4726305A (en) * 1986-06-19 1988-02-23 Pegasus Sewing Machine Mfg. Co., Ltd. Thread cutting device for cylinder bed sewing machine
US4984526A (en) * 1986-09-30 1991-01-15 Juki Corporation Thread chain guiding device for overedge sewing machines
US5868089A (en) * 1991-11-14 1999-02-09 The Singer Company N.V. Needle thread restraining device in a thread cutting sewing machine

Also Published As

Publication number Publication date
ES354872A1 (es) 1969-11-16
CH468503A (it) 1969-02-15
DE1760703B2 (de) 1977-12-15
FR1571911A (es) 1969-06-20
DE1760703C3 (de) 1978-08-10
DE1760703A1 (de) 1971-12-02

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