US1422407A - Thread cutter - Google Patents

Description

B. BECKER.

THREAD CUTTER. APPLICATION FILED SEPT. 6, I918.

L422A07; Patented July 11, 1922;

WITNESSES INVENTOR RUDOLPH BECKER, O35 ROSELLE- NEW JERSEY, ASSIGNOR TO TI-IE SING-ER, MANUFACTURING COMPANY, A CORPORATION O1 NEW JERSEY.

Specification of Letters Patent.

Patented July it, ft, 192.2.

Application filed. September 6, 1918. Serial No. 252,938.

To all whom it may concern:

Be it known that I, RUDOLPH BECKER, a citizen of the United States, residing at Roselle Park, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Thread Cutters, of which the following is a specifioation, reference being had therein to the accompanying drawings.

This invention relates to an improvement in thread-cutting means for sewing-machines.

The objects of the invention are to provide a simple and efficient thread-cutter operating with a shearing action, and to provide means thereon for guiding one limb' of a thread-loop within the jaws of the shears.

The thread-cutter in the embodiment shown is located in the work-arm of the machine and comprises a shear blade pivot-ally connected to the work-arm, a second shear blade having a floating pivot, a pivotal connection between the blades, means carried by one of the blades for seizing the needleloop and deflecting one limb thereof into the on substantially the line 4.4L of Fig. 3, the

blade 8 being shown in elevation.

In the drawings 1 is the machine base having a forwardly projecting work-arm 2 and overhanging arm 3, the latter carrying the usual needle-bar having'a needle 4. Pivotally mounted at 5 in the work-arm 2 adjacent the 'looper 4c is a member in the formof a bellcrank-lever, one arm 6 of which forms one of the shear blades of the cutter, the other arm 6' being connected to an operating link 7. A second shear blade 8 has a pivotal connection at a point 8' intermediate its ends with a spring wire or other link 9, the latter being bent downwardly and secured to the side-wall of the work-arm by a screw or other means 9 as shown in Fig. 4. The blade 8 also has a pivotal connection at 10 with blade 6. The back edge of blade 8, or the edge opposed to its cutting edge, has a cam surface at 8, adapted to engage with a straight portion or abutment 8 on the inner wall of the work-arm as the blade moves on its pivot 10. The spring wire link 9, in ad dition to serving as a floating fulcrum for the blade 8, forms a yielding means for holding the cam-surface 8 against the surface 8 thus opening the blades when blade 6 is re tracted, and bears downwardly against the blade 8 to thereby maintain'the cutting edges of the blades always in contact. It will be noticed that the blade 6 has a fined pivot, while the blade 8 has a floating one, and a toggle is formed between the pivot point 5 of blade 6, the bearing point of cam 8 on surface 8 and the point of connection of the blades at 10. Extending laterally from the end of blade 6 is a projection or nose 1.1, which acts to enter a threaddoop held by the looper and to deflect and detain one limb thereof for severance by the blades. The operating link 7 may be actuated in any desired man ner, and in the embodiment shown is connected to a stop-motion mechanism substantiall the same asthat shown in the patent to M. Horton, No. 1,051,998, dated F ebruary 4c 1913. It is obvious, however, that the actuating means for closing the blades may be applied in many ways and to either blade.

At predetermined periods in the operation of the machine a bellcrank-lever 12 (Fig.2) at the lower end of the stop-motion mechanism is moved to actuate link '7 against the tension of a spring 13. This causes the bellcrank-lever 6, 6 to move on its pivot 5 and through the pivotal connection 10 and the bearing of the cam 8 onsurface 8, blade 8 is oscillated about said pivot 10. This causes a relative closing movement of the two shearblades and asthe thread is caught between them it is severed. It will be noticed that as blade'6 moves toward the surface 8 the bearing point of the curved surface of the cam 8 on this surface 8 moves nearer the pivot 10 thus shortenlng its leverage and acceleratmg the relative movements of the two blades. This gives a comparatively slow of the cutting edges similar to a chopping movement thus givlng a more reliable opera tion. Because of this movement of the blade 8 given by the cam, the cutting edge is moved away from the surface 8 sufiiciently to cut the thread when it is substantially in line with the needle opening, but when theblades are opened the cutting edge of blade 8 is'retracted out of the line of the needle opening and so will not interfere with the thread or needle, as clearly shown in Fig, 3. The cam surface 8 and the abutment 8 may be dis pensed with if desired in which event the spring 9.wouldform a yielding means for closing the shear-blades to cut the. thread upon operation of the blade 6 instead of the positive means obtained with the use of cam 8 and abutment surface 8 In the movement of blade 6 the projectionv 11 has previously enteredthe thread-loop leading as usual from the looper and deflected and detained one, limb of thesame, which limb is severed by the-closing ofblades (Sand 8.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, a thread-cutter comprising a cutting blade having, a fixed fulcrum, a secondcutting blade having a floating fulcrum and-a cam-surface, a pivotal connection between-saidfblades separate from the floating fulcrum, means for actuatinggone of said blades, and means. coacting: withthe cam-surface for swinging the other blade about the pivotal connection between the blades.

2. In a sewing machine, a thread-cutter comprising a cutting blade having a fixed fulcrum, a second cutting blade coacting therewith having a floating fulcrum and a came-surface, a pivotal connection; between saidyblades intermediate their fulcrums, means for moving said first blade on its fulcrum, and, means coacting; with the camsurface to move the second blade about the pivotal connection between the blades.

3. In a sewing machine, a work-support, stitch-forming mechanism including a re ciprocating needle and a.complemental1looptaker, a fulcrumed cutting blade, a second fulcrumed cutting blade coacting with said first mentioned blade and having a link connection withthe machine,,one of said blades having. a portion so formed: and positioned as to venter between the limbs Of'a needleloop below the work-support, apivotal connection between said bladesintermediate their fulcra, and means for actuating said blades.

4. In a sewing machine having stitchforming mechanism and a stop-motion mechanism therefor,v a cutting blade pivotally mounted on the machine, a. second; cutting blade having a link connection with the machine and a pivotal connection with said first blade, and means operated by the stopmotion mechanism for actuating said blades.

5. In a sewing machine, a thread cutter comprising a pair of pivotally connected shear blades, yielding means for maintaining the cut-ting edges of said bladesin contact, said means forming a fulcrum for one of said blades separate from the pivoted connection between the blades, and means for actuating said blades; 7

6. In a thread-cutter, a pivotally mounted slieai blacle, means forv moving it about its pivot, a second shear-blade pivoted to thelirst mentioned shear-blade at a. point spaced from the first mentioned pivot, a cam ens-aid second shear-blade, and a fixed abutment against which said cam reacts; as a fulcrum during the movement of the first mentioned blade.

7. In a sewing machine, a threadcutter com risin a blade havin i a fixed fulcrum a second blade pivoted tothe first blade intermediate itscutting edge and its fulcrum,

the second blade being provided with a cam,

means on the machine cooperating with the cam, yielding means providing a floating fulcrum for the second blade and; acting to retain the cam against its cooperating means, and means for operating one of theblades 8. In a sewing machine, a threadrcutter comprising a pair of pivotally connected sheaiyblades, one blade being pivoted to stitch-forming mechanism including a. re-

ciprocatingneedle andiacomplemental looptaker, and cooperatmgshear-blades mounted on the same side oftheworl: as'the loop;

taker, one of said blades being formed with a loop -dividing point which is so positioned as to be projected duringthe closingmovement of said blades into the last needle-loop whileheldspread by the loop-taker.

Inxtestimony whereof, I have signed my name tolthis specification.

,snnoLrl-i BECKER.

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