US1935083A - Thread cutter for buttonhole sewing machines - Google Patents

Description

NOV. 14, w w NNELL JR THREAD CUTTER FOR BUTTONHOLE SEWING MACHINES Filed May 13, 1932 3 Sheets-Sheet 1 Fig. 1-.

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Nov. 14, 1933.

W. W. DUNNELL, JR

THREAD CUTTER FOR BUTTONHOLE SEWING MACHINES Filed May 13, 1932 5 Sheets-Sheet 2 lnvenTor.

NOV. 14, 1933. w; w DUNNELL, JR 1,935,083

THREAD CUTTER FOR BUTTONHOLE SEWING MACHINES Filed May 15, 1952 5 Sheets-Sheet 3 59 L- 24 InvenTor.

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Patented Nov. 14, 1933 THREAD CUTTER FOR BUTTONHOLE SEWING MACHINES William W..Dunnc1l, J-r., Boston, Mass assignor to The Reece Button Hole Machine Company; Boston, Mass., a corporation of- Maine Application'May 13, 1932,. Serial ,No. 611,077

3 Claims. (Cl. 112-252) This invention relates to buttonhole sewing m chines ofthat type in which the under thread mechanism is carried by a turret which is situatedbeneath the work and is rotatively mounted f r urningmovem nt.

The invention relates particularly to means for trimming the under thread and stay cord close to the work at the end of the .sewing operation.

,One'of the objectsiof the invention is to provide a novel thread cutter which operates underneath the work between'the latter and the throat plate and which is given its thread-cutting movement by the reverse rotation of the turret which occurs. after the sewing operation has been completed and before the machine comes to rest.

In order to give an understanding of the invention I have illustrated in the drawings a selected embodiment thereof which will now be described after which the novel features will be pointed out.

in the appended claims.

,liig. 1 is aside view of a portion of a buttonhole sewing machine embodying the invention;

Fig, 2, is a top plan view of the work-holding means and the cutter for cutting the under thread and stay cord;

' 3 is a section on the line 33, Fig. 2;

Fig. 4 is a view .of the turret carrying the under thr d mec n m;

Fig. 5 is a top plan view of the turret illustrating the means for operating the under thread cutting device;

Fig, 6 is a section on the line 66, Fig. 4;

Fig, 7 is a section on the line '77, Fig. 4;

.Fig, 8 is a fragmentary sectional view showing the manner in which the under thread and stay cord are drawn around the edge of. the cutting element just before the cutter operates.

The buttonhole'sewing machine herein illustrated has the usual work-holding means which is mounted on the bed plate 1 and the'usual stitchfo ming mechanism which is carried by a stitch frame indicated generally at 2. The stitch frame and the .bed plate have a movement relative to each other during the sewing on the buttonhole and also a further relative movement to carry the parts from stitching to buttonhole cutting position as usual in buttonhole sewing machines of this type.

The work-holding means comprises work clamps 3 by which the work 4 is clamped against the mats 5 which are carried by the clamp plates 6, the latter being removably mounted on the bed plate 1 as usual.

The stitch-forming mechanism comprises the usual needle 7 carried by a needle bar 8 which is mounted for reciprocation in the stitch frame 2,

and also under thread mechanism carried by the turret 9 which is rot'atively mounted in the portion 10 of the stitch frame on the opposite side of the work from the needle. i

The turret 9 carries the usual throat plate or button 11 which is provided with the sewing opening 12 through which the needle '7 operates.

The under thread mechanism is of that known type which comprises loopers and loop Spreaders (not shown) which are carried by the turret 9 and the looper mechanism is actuated through the medium of'two co-axial spindles 18 and 24 which are mounted for vertical reciprocation in the turret, the spindle 18 being connected through a link 17 to an oscillating block which carries the looper, and the spindle 24 being connected by a link 23 to the wedge for actuating the loop Spreaders. These spindles are connected at their lower ends to levers 19 and 25 which are pivota'll-y mounted on the portion 10 of the stitch frame as indicated at 20 and 25 and said levers 19 and 2 5 are connected by links 21 and 27 to appropriate cam-actuated levers (not shown) such as are usually employed in buttonhole sewing machines of this type for actuating the looper mechanism. I

In the operation of the buttonhole sewing ma-' chine the stitchframe 2 and the work-holding means have a relative feeding movement during the sewing of the buttonhole and when the buttonhole has been completed and the stitch-form ing mechanism has come to rest with the needle retracted as shown in Fig. 1, said stitch frame and work-holding means have a further relative movement to carry the parts from stitching to buttonhole cutting position. The full lines Fig.

1 illustrate the position of the parts at the completion of the buttonhole sewing, andthe dotted lines indicate the position of the stitch frame when shifted into huttonhole cutting position.

During the sewing on the buttonhole the under thread 28 is led to the work from the threaded looper through the sewing opening 12" of the throat plate 11 and the stay cord 29 is also led to the work through said sewing opening 12; When the parts are shifted from stitching to buttonhole cutting position the stitch-forming mechanism moves forwardly, or. to the right Fig. 1 7 relative to the work-holding means and to the work held thereby, and during this forward move- .ment'a length of under thread 28 and stay cord 29 will be drawn out through the sewing opening 12 as shown in Fig. 5 so that when the parts reach buttonhole-cutting position there will be cord 29 extending from the stitched buttonhole 30 to the throat plate 11 and lying on the oppo site side of the work from the needle. Since Fig. 8 is a view looking at the turret from the side opposite to that seen in Fig. 1, the movement of the turret and throat from stitching to buttonhole cutting position will be toward the left in said Fig. 8.

The present invention relates to the thread cutter and the means for actuating it by which the under thread 28 and stay cord 29 are cut close to the work.

The thread cutter is similar to that shown in the co-pending Pikul application Serial No. 525,092, filed March 25, 1931. This cutter consists of a swinging cutter element 79 fast to a stud 80 mounted for turning movement in one of the clamp plates 6. This cutter has an arcuate work-positioning edge 81 and a thread-engaging finger 82 which is provided with a cutting edge 83. v 1

During the sewing on the buttonhole the cutter "/9 is positioned as shown in Fig. 2 with the work-positioning edge 81 crossing the sewing opening, it being held in this position by a spring 54 so that when the stitch frame and workholding means have their relative movement after the stitching of the buttonhole is completed to carry the parts from stitching to button-holecutting position, the length of under thread and stay cord which have been pulled through the sewing opening 12 of the throat plate will be drawn tightly around the work-positioning edge 7 81 and the latter will serve to hold the work properly positioned. It will be understood that the work clamps are opened before the cutter is actuated to cut the under thread and stay cord.

Means are herein provided for giving the thread cutter '79 itsthread-cutting movement directly by the reverse turning movement of the turret which occurs after the completion of the sewing of the buttonhole. I

For this purpose the stud 80 is provided with an arm 55 carrying a roll 56 and the turret 9 is provided with an upstanding arm '70 which carries at its upper end a cam member 57 adapted to engage the roll 56 during the reverse turning movement of the turret in the direction of the arrow Fig. 5 thereby to turn the stud 80 and thus give the trimming knife 79 its operative threadcutting movement. This is shown in Figs. 2

v and 5.

tion.

The dotted lines in Fig. 2 indicate the position of the turret and the cam member 57 relative to the roll 56 after the stitching on the buttonhole has been completed and the parts have been moved from stitching to buttonhole-cutting posi- In this position the cam member 5'? is closely adjacent the roll 56. When the turret is given its reverse turning movement in the direction of the arrow Fig. 5 the engagement of the cam'member 57 with the roll 56 will turn the pivotally connected. The turret is shown as hava length both of the under thread 28 and stay stud 80 thereby giving the knife '79 its threadcutting movement as shown by dotted lines Fig. 5.

In the operation of the under thread mechanism it is desirable that the spindles l8 and 24 should be held from turning movement as they are reciprocated so that the links 1'? and 23 may always be operated in the correct position.

The spindles 18 and 24 have crossheads 59 and 60 fast thereto to which the links 17 and 23 are ing a vertically-extending guiding fin 61 secured thereto and the crosshead 59 is provided with a forked extension 62 which embraces said fin. The crosshead 60 is similarly provided with a forked extension 63 which also embraces the fin. The same fin thus guides both crossheads in their vertical movement and prevents any turning movementof the spindles and thus any tendency of the parts to bind.

I claim:

1. In a button hole sewing machine, the combination with work-holding means, of a stitch frame, stitch-forming mechanism carried thereby and including under thread mechanism, a turret rotatably carried by said frame and on which the under thread mechanism is mounted, a thread-cutting member pivotally carried bythe work-holding means, said turret having a reverse rotative movement at the completion of the buttonhole, and means to give the cutter member its operative movement by such reverse movement ofv the turret.

2. In a buttonhole sewing machine,- the combination with work-holding means, of a stitch frame, stitch-forming mechanism carried thereby and including under thread mechanism, a turret rotatably carried by said frame and on which the under thread mechanism is mounted, a threadcutting member pivotally carried by the workholding means, said turret having a reverse rota- 115 tive movement at the completion ,of the buttonhole, an arm rigid with the cutter and a cam carried by the turret adapted to engage said arm duringsuch reverse rota/tive movement thereby to actuate the cutter.

3. In a buttonhole-sewing machine, the combination with work-holding means including clamp plates on which the work rests, means to clamp the work against saidplates, of 'a stitch frame, stitch-forming mechanism carried thereby 125 and including under thread mechanism, a turret, rotatively carried by said stitch frame and on which the under thread mechanism is mounted, said turret having a reverse rotary movementat the completion of the buttonhole, a thread-cut- 130 ting member for trimming the under thread and stay cord operating between the work and the. clamp plates, an arm rigidwith the cutting memher and situated beneath the clamp plates, and a cam member on the turret for engaging the arm 135 thereby to give the cutter its operative movement as the turret has its reverse rotative movement.

WILLIAM W. DUNNELL. JR.

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