US2597519A - Thread nipper - Google Patents

Description

F. M. O'BRIEN THREAD NIFPER May 20, 1952 INVENTOR.`

Filed June 2l, 1949 Francis M. O'Brien wwhmqmwm,

ATTORNEYS Patented May 20, 1952 :UN ITE D- S PATE N Tf Y.F-1:' [C E WQJTHREAD NIPPER .Fr ancis M.( )?Brien`, St. Petersburg, Fla. "ApplicationjJune 21, 1949,;Seria1N0...100,413

551 latim. (Cl.. 30\ -253) 'ine-common* with the. implement of..thalt;iprior patent; the present invention .aims v.toL-provide a .i

-` 'conventional scissors inlwhichaconcealedrspring r`functions -tcwmarintain the-cuttingbladesin an open positionA and toreturn the blades =.to` this `*Hopen position after each manualsactuation to close the bladesupon the thread; =.thler.ebeing also-'included a limit-StOp-toreStriCt.theextreme *movements of lthe scissors blades. ini both-.open and closedlpositions.

- In the drawingswherein the symbols refer to likeor correspondingparts throughout the sevq eralviews,

`: Figure 1 is aperspective View of a threadnipper constructed in accordance with the present invention and shown held in a position of operation.

f Figure 2 is a side elevation, taken onan enl larged scale of the device in normal open position.

- in -thepriorpatent referred to `the pivot-'C on 1 which the blades A andBrelativelytrock is displaced -fromall partsof--the springie and-.particu- -larly and critically from the hinge .portioni of the spring -which connects the Atvvoarms of; the, spring and about; which thesearms movea in thegiexing l of the spring. L `This Aoifsetting.ofthe spring. hinge from `the-blade pivotputsatwisting moQn and Figure 3 is a longitudinal section taken on the line 3 3 in Figure 2 and Fig-ure 4 is an explodedviewshowing in perspective theblades, spring and pivot bolt'I separated.

Reierring more particularly to the drawings,

It and-Il I represent the twoblades or members constituting the scissors and having the cutting edges I2 and I3 respectively.v The outer edges of a-*strainon theientiresspring durngjhe. Operation A f of the-thread nipperxwhichshortenstherli@ and actually impairs :the action;of the; spring.

Anobject of .the invention; is. to soleorganize andi-reconstruct the .parts I;of1;the .blades which reinge: is brought into `.coincidence- Withfthe pivot.

vdesirable.twistingtof theaspringparts landstrain f mwhichfthe same -hasibeenheretoiere Subisted f to revise f It .isanother objectof theainvention the .formioi spring over that disclosed in e =prior offioisetlends-jof suchyhelix; this vfeaturefpf ima helical Spring ,butWhere-the spring hinge'A is coa: post or bearing- 4shaftffor .the coil, supDQrting.

fThis. new. -location ,of ,the .Spring-:01kg QmmOn theblad e s opposite thecutting edges areflared orotherwise operated uponA to produce the pads I4 and 151er the comfort of the nger or thumb .i y ywhen used `in compressingithe scissors.

. '1 -he two blades I0 and I I are pivoted together bythe t)grrivotscrew I6for other suitable means, the

vhead of Whichts against one of the members I I f 1 and alsothrough a perforation IBin the .other center'with .the fpivat: point eliminates the un-.

memberor blade I0. The pivot bolt I6 is vprovided With an outerthreaded portion I9 and an At least a part o f the outer threaded portion I9 projects beyond the outer face of the blade or member IB Where thesame receives a nut 2| for binding the p ivot bolt I6 in place.

As shown more particularlyV in Figure 4 the blade I I jisformed with a partial socket 22 which 1 .is adapted to overlie and complement a similar incident with .the :blade-pivot that 'helical form` offspringhingecooperateswith the pivotpin to` enablethe pivotpin-to pass throughthehelix as iff andfholding rthe,SpringinpIace andgrendering p the...action. of .the -assembly-lmuch smoother and snappier, and also. requiring less .ngerpressure onthe DartV of the operatorto closethejnippen.

ordinary quickness.

A further object of the inventiony i s=-to'j`p1ovide i( while assuring that .the blades 0pm' w-ith"extra'- partial socket `23 in thecompanion blade I0; it

` beingunderstood that these sockets are made in vthe mutually inner faces of the blades I I and I Il and thatwhen ,these blades are assembled together thefsockets 22 and 23 .will mate and produce av-closed cavity coaxial with the perforations I'I, I8 andcoaxial with vthe axis of the pivot bolt I6. The sockets22, 23 communicate with elongated recesses 24 and-25 respectively inthe inner faces `of thebladesII and I0 and these recesses,

like the sockets-22 and23 openoutontheinner l'13a thread nipper ofv the'character above'describedi With the foregoing and other objects. in view, :atheinventiongwillbe more fully described hereinafter, and :willi-be,more1pa1ticularly; pointed out E i intheclaim appended hereto.

-- in 4"which the reconstruction andrearrangement facesot the V blades but are concealed by the outer v portions loftheblades.' f These recessesextend off theirv `vrespective' .sockets Y in directions longitudinally of the blades which are rangularf to one another when the blades are assembled together. In

Figure-1.4 y.the no n gitudinai.direction@ both reisshown:inclininggnpwardly tov .fromtherespectvesockas22 and 2 3 butwhenthe, blade I I isturned over tomate with its companion blade I the recess 24 will not accurately mate throughout its area with the recess 25 but will be slightly angularly offset therefrom.

The recesses 24 and 25 preferably taper in the direction away from the sockets 22, 23 and cavities or bores 26 and 21 are made in the blades I I and I0 respectively communicating with the upper narrower ends of the recesses 24 and 25.

A spring helix 28 is adapted to be received in the sockets 22, 23 and about the shank of the pivot bolt I6. This helix 28 has spring arms 29 and 39. One spring arm comes tangentially off vallargare one end of the helix 28 while the other spring arm 30 comes tangentially off the other end of the helix. The tangent points are preferably substantially diametrically offset one another so that at the end convolutions of the spring helix or spring hinge 28 the arms 29, 30 are in relatively angularly displaced positions with the arms 29 and 30 preferably diverging to such an extent that when assembling these arms 29 and 30 will have to be moved together on the circle of the helix 28 in order to cause both such spring arms to register with the recesses 24 and 25 which are designed to receive these spring arms with the ,terminal ends of the arms tted into the cavities 2B and 21. This helix or coil stack is preferably formed from a single vstrand of resilient wire coiled intermediate its ends into a suitable number of convolutions. The spring is wholly concealed and protected by the blades I0 and II. The potential energy and torsion given the spring is such that when the same is in the position shown in Figure 4 alone and apart from the pocketed construction of the blades vIl! and Il, the spring arms 29 and -30 will inherently seek an angular outstretched position which is greater than the distance by which the recesses 24, 25 are offset. This arrangement requires that the spring arms 29, 30 be moved angularly together to bring the same in alignment with the recesses 24, 25 in Vwhich they are inserted and this action places the helix 28 under the necessary tension. The spring tends to open at all'times and to spread the spring arms 29 and 30 which react against the side walls of the recesses 24, 25 and also against the walls of the cavities 26, 21, thus biasing the blades I0 and II to the open position shown in Figure 2.

By inserting a finger' through the finger hold 3I and otherwise grasping the device'in the manner generally indicated in Figure 1 and with the thumb and first finger exerting pressure on the pads I4 andV I5, the cutting edges I2 and I3 may be closed by manual pressure against the influence of the torsion spring. During such movement the spring arms 29, 39 will be rotated to gether to further wind the spring convolutions 28 and to store energy in the spring. When released the spring will react to force the scissors blades I9 and II into the open position.

A stop screw or other abutment 32 may be carried by one of the blades, for instance the blade In in position to occupy a stop socket 33 produced in the inner face of the companion blade II; it being understood that the diameter of the socket 33 exceeds that of the stop projection 32 by an amount preselected to limit the through or relative angular movement of the blades I0 and I I in both opening and closing movements.

In assembly, the two blades are brought together on the spring with the ends of the spring arms 29 and 30 being slid upwardly into the cavities 21, 25 so that the spring arms fall into the recesses 25, 24 while the spring helix or hinge is received in the socket 23, 22. The pivot bolt I6 is then inserted through the openings I1, I8 and it will be found that the open or hollow spring helix or hinge 28 is in registry with the openings I1, I8 so that the bolt I8 is also received therethrough. The nut 2l is thereupon run upon the projecting end of the bolt I9 and tightened up, the nut 2I being larger in diameter than the opening I8 and therefore abutting against the outside face of the blade I0. The nut 2I is tightened so that the correct cutting pressure is exerted on the cutting edges I2 and I3. This cutting pressure or shear is heightened by the fact that the coil stack 28 engaging against the inner walls of the sockets 23, 22 tends to move the blades I0 and II apart. this tendency being overcome by tightening the nut 2|. The nut 2I and its companion bolt I8 therefore constitute not merely a form fastening or a pivot axis for the blades but the arrangement also serves to adjust the tension of the coil spring 28 insofar as it tends to move the blades apart and place tension shear on the cutting edges I2, I3. Thus the form of helix 28 has a double function, namely to place the spring arms 29 and 30 under a tension in a torsional or rotary sense to open the blades after release following each closing operation; but the spring coil is also of such axial length that it is put under compression when the nut 2I is finally tightened and its tendency to react and expand axially causes the blades to tend to move apart and thus places shear tension on the cutting edges I2, I3. Where the spring helix or hinge 28 is offset from the pivot axis it is necessary to insert the spring, hold the blades together with the openings in line and insert the bolt I6. This is difficult because the spring tends to push the blades apart.

With the new assembly in which the helix 28 is coaxial with the pivot I6 the assembly of the nipper is easier because the spring may be held by the bolt during the assembling operation. In other words the bolt I6 may be tted through the perforation I1 and the spring helix 28 entered over the shank of the bolt and the threaded end I9 of the bolt afterwards passed through the opposed perforation I8 of the other blade I0, the nut 2I being subsequently run upon the outer end of this threaded portion I9. The spring armsl 29 and 30 are of course sufllciently flexible to be bent or curved momentarily out of shape for the purpose of fitting the terminals thereof into the cavities 26, 21.

The reorganization and reconstruction of the device with the axis of the coil helix 28 and that of the pivot bolt I8 coincident has greatly improved the action of the thread nipper itself and in addition greatly prolongs the life of the spring for the reason that the bolt passing through the hollow helix itself adds considerable support to this member. The new method of construction also facilitates the replacement of springs when necessary.

The helix 28 preferably ts over the plain unthreaded portion of the pivot bolt I6 so that changes as may come within the scope of the following claim.

What I claim is:

A tool of the character described comprising a pair of blades having complementary cutting ends and opposing hinged ends, said last ends being formed with registering transverse openings and partial sockets formed on the inner faces of the ends and arranged coaxial with the openings, said sockets communicating with elongated recesses Which taper longitudinally of the blades from the sockets toward the cutting ends, said blades having longitudinally disposed bores communicating with the tapered ends of the recesses spaced from the openings, a spring having a helix coil and arms extending outwardly from the helix, said coil being seated in the sockets and arranged transversely between the blades with its ends disposed in the recesses and received at their free terminals in the bores,

6 the opening of said coil being aligned with the openings in the blades, a pivot passing through the openings and said coil, and means carried by the pivot for clamping the blades together.

v FRANCIS M. OBRIEN.

`ile of this patent:

UNITED STATES PATENTS Number Name Date '772,275 Downing Oct. 11, 1904 1,186,235 Schrade June 6, 1916 1,299,104 Arnold Apr. 1, 1919 2,392,118 Cacarillo Jan. 1, 1946 FOREIGN PATENTS Number Country Date 276,262 Germany July 8, 1914

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