US2421712A - Buttonhole sewing machine - Google Patents

Description

V Julie 3, 194%. 'w. E, NICHOLS V 2,421,712

BUTTONHOLE SEWING MACHINE Filed Jan. 9, 1945 I 2 Sheets-Sheet 1 bum 8.1mm.

' INVEWFU June 3,1947. w. E. NICHOLS 2,421,712 I BUTTQNHOLE SEWING MACHINE Filed Jan. 9, 1943 2 Sheets-Sheet 2- v INVE'N4'UR:

Patented June 3, 1947 Walter: ELNi-chols, Milton, Mass, assignor'to The Reece" (Corporation; a, corporation 015 Maine- 'ApplicationJ'anuary 9, 1943', Serial No. 471,843

3 Claims: 1 i his inventionrclates tosewin'g machines, and especiallyto buttonhole sewing machines of the" type linown as straight hole machines such as those described in Patents Nos. 714,284, Novem- February 24, I914; 1,4025073", January 3; 1922 and 1,48%,3fli; February 12, 192i.

The invention. relates particularly to an; improvement in thread cutting. or trimming mech anisms; for machines of this and other types in, 1'0

which the: trimming mechanism is operable uponthe completion of the. stitching operation to set' the final; stitch and then to cut or trim the thread;

Buttonhole" sewing" machines of the straight hole type include a cutter for cutting the but- 1 5* tonhole slit substantially upon the completion of" the stitching operation and another cutter operable immediately thereafter'to severor trim the sewing"; thread; In some suchzmachine's", the butslight continued movement, usually-termed over-'- throw, andwhich is; in effect, a jolt or far given at the time when the-moving parts-became locked;

This dependence; for the operation of the thread trimmer, upon the stopping impact, overthrow, or momentum of the machine", which may'vary considerably 'under variable conditions, has re sulted in unreliable and: uneven trimming.

Theobject' of the present inventionis to avoid" possibility of premature operation-{of the thread trimmer; andinterference between the latter-and thebuttonhol'e cutter, as aforesaid; and to provide means for'operating'said'trimzmer with auni form, positive action; consistently and absolutely contingent upon thecutting operation and suitsequent retraction of said: cutter,- independent of the impact of the stopping mechanis and urnlimited by the momentum of the machine The invention will best be understood from the ton-hole. cutter is" timed to operate just prior to; fbi'1oWiI-1g-description: of an illustrative embodi the" completion of the sewing cycle, usually during the, formation. of the last stitch, and the thread trimmer to operate immediately upon the completion of'the last stitch and", the stopping of ment thereof shown in the accompanying draw ings.

In the-drawings:

Fig. 1 is avi'ew in sideelevation, partly insecthe machine. In many such machinesthe but: W311 d P broken" away"; o maighihe' tonhol'e cutter and the threadtrimmer are obliged; to operate in intersecting or closely adjacent paths: Normally the buttonhole cutter completes: its operation andis retracted" or raised just'prior to the operation of. the thread trimmer, but if the button-hole cutter should for some. reason become jammed in the work and fair to rise: promptly, there is: a: possibility of, its being struck by the thread; trimmer with resulting damageto either: orbothof them.

Attempts havev heretofore been made to avoid interference of this sort by making the operation. of the thread trimmer automatically contingent upon. the retraction ot the; buttonhole cutter, as:

by" providing an operative connection, between the trimmer and its actuating means, which is" automatically disabled or uncoupled except when the buttonhole cutter is in rctractedpositionm Even with such an arrangement, however, it is,v

the parts, for the trimmer actuating means to causea premature operation ofthe trimmer when. the huttonholecutter has been moved partly out of its fully retracted position but before completion of itsbuttonhole cuttingstroke.

In machines of the straight hole type referred to; as: heretofore constructed, the thread? trimmer received its movement solely from themoment-umor the machine at thetimewhen the;

body-i'ng the prevent invention, showing theparts in the positions: they occupy when the thread trimmer is in operation. Fig; 2isa perspective viewofi the thread trim- 30 merandassociated partsl l pussible,v due t0 wean roughness and sticking: 4-5 stitches along the sides oi" the buttonhol'e.

Fig. 3 isa plan view of the machine oflif-igil, partly in section and'p'artly broken away.

Fig. 4' is a fragmentary viewin end elevation as viewed from the right in Figs. 1 and 3.

The machine shown. im the drawing-si'may, as

to its general organization, be: similar to those described in the patents above referred to: It

comprises abed M from which rises a standard lEoar-rying an overhanging arm l'fii spacedi above the bed; The work W is carriedfby at work clamp or holder comprising a clamp plate FE and coopcrating clamping arms 8, said: work: holderbeing movable as a unit overrthelbaed, bymechanism generally indicated eel-am orderto position; the The stitch-forming instrumanta'lities comprise an? eye pointed needle 2 ll above": the work and coopem. ating' loopers or equivalent under thread me'cha nism 'or handling devices: 2l below the work, there being a throat plate 22 carried by the bed f4 and having an opening through which theneedle operates. The needle 20 is carriedby' a needle bar 23 which is longitudinally and verticallyreciproeated, by means generally indicated? at 2'4,

resiliency of the stopping mechanism allowed 8; 5* in a needle bar guide 253 means; not shown, bee

ing provided for oscillating said needle bar guide alternately in opposite directions transversely to the direction of feed of the work clamp between successive strokes of the needle to position the depth stitches. The thread if is taken from a suitable source and passes to the needle eye through a take-up 26 and suitable tension devices 21 and 28, after which it passes through the work and throat plate to the loopers 2!. A main shaft 29 journalled in suitable bearings in the bed has power applied thereto by a belt 30 alternatively engageable with fast and loose pulleys 3i and 32 under the control of a belt shifter 33. The belt shifter 33 constitutes an extension of a stop member or arm 34 carried by an oscillating and longitudinally movable rock shaft 35 mounted for oscillation and a limited longitudinal movement in the bed l4. Associated with the sliding rock shaft 35 is a spring 36 (Fig. 3) surrounding said shaft and interposed between a collar 31 and one of the bearing brackets or ears 38 in which said shaft is mounted, said spring tending normally to move said shaft toward the right in Fig. 3. Slidably mounted in the stop arm 34 is a stop element or bolt 4| normally urged toward the right in Fig. 4 by a spring 42. At its end the bolt 41 is formed with a nose 43 which is in the path of movement of a cam 44 fast on the shaft 29 when the shaft 35 is in the longitudinal position to cause the belt shifter 33 to engage the belt 30 with the loose pulley 32. Cam 44 has a concentric portion a, a rise b, a notch c and a stop shoulder d, arranged to engage the nose 43 in the order named when the shaft is rotated in the direction of the arrow in Fig. 4.

A spring-pressed plunger 45 carried by the upright standard I engages the stop arm 34 and tends to turn said arm and the rock shaft 35 in a clockwise direction as shown in Fig. 4 to press the nose 43 against the periphery of the cam 44' when said nose lies in the path of movement of said cam. A starting lever 46 is secured to a rock shaft 41 and is normally urged clockwise in Fig. 1 by a spring 48. One arm 49 of said lever is connected to a treadle T, as by linkage 50, and another arm'5l' is adapted to engage the collar 31 and move the shaft 35 to the left in Fig. 1 when the treadle is depressed. 7

A detent 52 is adapted to engage a notch 53 in said shaft 35 to hold said shaft in its left-hand positionduringa sewing operation, other means, (not shown) serving to automatically release said detent at the beginning of the last stitch-forming cycle.

The buttonhole cutter 54 is carried by a lever 55 journalled on a short stud shaft 56 supported in the bed, said lever having an arm 51 carrying at its end a sleeve 58 in which is journalled a stud 59 having at one end a sleeve portion 66 which receives a stud 6! extending inwardly from the stop arm 34.

The combined stitch setting and thread trimming element 14 is guided in ways in the bed I4 immediately below the throat plate 22 and between the latter and the loopers 2| (see Fig. 2). The element 14 is provided with an opening 15 adapted to receive a stud 16 carried by an arm 1'1 fast on one end of a rock shaft 18 journalled in suitable bearings in the bed I 4. At the completion of the last stitch forming cycle, and substantially coincidentally with the stopping of the machine, said element is moved from its normal retracted position shown in dotted lines in Fig. 2 into engagement with the thread loop as Shown in the full line position in Fig. 2.

another arm 64 extending into the upright into a position to engage an extension 65 of the lever 66 which carries the clamp arms l8. By moving the finger piece 63 inwardly (to the left in Fig. 1) the clamping arms l8 may be raised against the tension of the spring 6'! to release the work. Conversely, when the .clamp closes under the infiuence of the spring 61, the arm 64 is moved upwardly and the finger piece 63 moved outwardly (to the right'in Fig. 1). Pivoted at 68 to the arm 64 is a depending link 69 carrying a catch 10. The link 63 is normally urged by a spring H in the direction to cause the catch 10 to engage a lug 12 carried by the arm 51 of the buttonhole cutter lever 55. when the buttonhole cutter 54 rises, the arm 64 is normally drawn downwardly to open the work clamp. The catch 70 may, however, be disengaged from the lug 12 by a trip finger 13 secured to the shaft 41. The trip finger T3 is moved into a position to move the link 69 to the left (Fig. 1) and thereby disengage the catch 10 from the lug 12 when the treadle T is depressed, so

that depression of the treadle to start the machine serves to disconnect the clamp and the buttonhole cutting mechanisms and permit the clamp to close.

The shaft '18 has secured thereto, at a point intermediate its ends, an arm 19 pivotally connected by a link to the arm 8| (see particularly Fig. 4) of abell crank 82 pivoted at 83 to a bracket 84 (see also Figs. 1 and 3) secured as by a screw 85 to the underside of the bed M. The other arm 86 of the bell crank 82 is pivotally connected by a link 81 to the arm 64 of the clamp raising lever. Consequently, when the lever arm 64 rises, the trimmer 14 is retracted, and when said lever arm is drawn downwardly, the trimmer is advanced into the position shown in full lines in Fig. 2.

In operation, the operator starts the machine by depressin the treadle T to rotate the starting lever 46 counterclockwise and move the rock shaft 35 to the left in Fig. 1 to shift the belt 36 from the loose pulley 32 to the fast pulley 3| and move the nose 43 out of the path of movement of the cam 44, said shaft 35 being retained in this position until the beginning of the last stitch-forming cycle by the engagement of the detent 52 with the notch 53. Depression of the treadle also causes the trip finger 1,3 to disengage the catch 16 from the lug 12, thereby permitting the work clamp to close under the infiuence of the spring 61, raising the lever arm 64, and retracting the trimmer 14. The treadle is then released, permitting the spring 48 to restore the lever 46 and trip finger 13 to the position shown in Fig. 1. When the detent 52 is withdrawn from the notch 53 at the beginning of the last stitch-forming cycle, the spring 36 causes the shaft 35 to move toward the right in Fig. l to shift the belt 30 from the fast pulley 3| to the loose pulley 32 and again bring the nose 43 into the path of movement of the cam 44. During the formation of th last stitch,'the

Consequently,

, provement of considerable advantage.

. meiiine it sunder its wn; monientumfandthe nose *43 follows th periphery of the cam? until lever 5, tolift said arm5'l andthereby advance plunger 45, enters the notch "c, this movement causingf the "buttonhole cutter 54t'o be retracted or "raised-rtoits original or'inoperative position.

,As the lever 55 is raised, the arni 51 is lowered,

andthe lug-12 eng es thecatch lfl inthe link 69 and pulls downwardly onsaid link, whichin turn depresses the arm 64 of the clamp raising lever 63. As the arm 64 is depressed, it operates through the link 8'!, bell crank 82, link 80 and arm 1-9 to rotate the shaft 18 clockwise in Fig. 4. This rotation of the shaft 18 operates, through the arm 11 and stud 16, to advance the trimmer 14 from the position shown in dotted lines in Figs. 2 and 3 to that shown in full lines in the same figures, this movement acting to set the stitch and trim or cut the thread loop.

It will be observed that the trimmer is operated from the buttonhole cutter lever during the rise, or retraction, of the cutter, and that the connections for operating the trimmer (including the link 69, catch and lug 12) are disabled or disrupted when the machine is started and are not restored until the cutter has descended on its cutting stroke and subsequently rises. Therefore, the trimmer I4 cannot be prematurely operated; it is operated only when the buttonhole cutter 5-4 has completed its cuttingstroke and has been raised out of the work and is consequently out of the pathof movement of said trimmer. The spring pressed plunger 45 is the means used to raise the buttonhole cutter lever 55, and is also the source of power for actuating the trimmer 14, the arm 51 of the lever 55 and the arm 64 0f the clamp raising lever serving as a part of the system of linkage connecting the spring pressed plunger 45 and the trimmer I4.

The use of the spring-pressed plunger 45 instead of the stopping mechanism for furnishing the power for operating the trimmer is an im- It has been found in practice that the cutting of a relatively small buttonhole requires less force than the cutting of a large buttonhole. If the cutting operation takes a larger proportion of the power supplied by the momentum of the machine, it correspondingly-leaves less for the operation of the trimming mechanism and may result in incomplete operation, of the trimmer, and conversely, when the cutting operation requires a small part of the force supplied by the momentum, the remaining larger force of the momentum, if it is not absorbed by readjustment of the spring loaded plunger 45, will increase the wear and shock on the stop motion parts. If the momentum of the machine is used to operate the trimmer, the variation in the size of the buttonhole cut tends, therefore, to cause a corresponding variation in the operation of the thread trimmer.

6 ""Very careful machining, smooth surfaces, frequent lubrication, i and adjustment of the spring loaded plunger to balancethe amount of momentum necessary for trimming and stop 'ping are required if the momentum of the machine, acting through the stopping mechanism, is to be successfully used to operate the trimmer. roughness or irregularity of the cam 44, for instance, tendsto cause the trimmer to receiveits impulse simultaneously with the movement of the buttoriholecutter, and 1 these v ariations in opera tion are,fof 'coursefaptto be increased asthe parts begin-to wear, The utilization of thespring pressed plunger-45 as a source of power for the openness the trimming mechanism, however, provides'aeonstant, unfluctuating" force, the application-of which to the trimming mechanism is always contingent upon the pr'oper elevation of the button hole cutter 54 due to the factthat a part of the cutter 1 operating mechanism forms a I link in the chain of elements 1 connecting the plungerandthe trimmer. i

The connection with the arm 64 of the clam raising lever also provides for operation of the trimmer independently of the automatic operation of the machine. If, for instance, the operator wishes to inspect the work or remove it for any reason before the completion of a sewing operation, he can stop the machine and move the finger piece 63 inwardly to raise the clamps and release the work. Formerly, the work was held by the thread, but in the machine of the present invention the thread is trimmed as the clamps are raised, allowing the operator to move the work freely or remove it entirely.

I claim:

1. In a straight-hole button-hole sewing machine having a single cycle of operation during which the sewing is done and the button-hole is cut and the thread is severed, in combination, a button-hole cutter, a work clamp, clamp raising means, a thread trimmer, means operative during the formation of the last stitch to depress the button-hole cutter to cut a slit in the work,means operative thereafter to retract said button-hole cutter, a releasable connection between said button-hole cutter and said work clamp raising means, means for releasing the connection when I depressed, and means connecting the clamp raising means and the trimmer, said releasable connection after the button-hole cutter is depressed being operative during the rise of the cutterto button-hole cutter, a work clamp, clamp raising means, a thread trimmer, means operative during the formation of the last stitch to depress the button-hole cutter to cut a slit in the work, as

the needle rises on the last up-stroke, means operative thereafter to retract said button-hole cutter, a releasable connection between said button-hole cutter and said work clamp raising means, means for releasing the connection when the machine is started, means for re-establishing the connection only when the button-hole cutter is depressed, and means connecting the clamp raising means and the trimmer, said releasable 2&2157112 connection after the button-hole: cutter is depressed being operativeonly =duringethe rise of the cutter to transmit force derived from the cutter. retracting means directly tothe clamp raising means and acting through said last named, means to move th e; trimmer to sever the thread. 3.111 a straight-hole button-hole sewingmachine'having a single cycle of operation during which the sewing is done and the button-hole is cut and therthread-is severed, in combination; a button-hole cutter; a work clamp, clamp raising means, a thread trimmer, means operative duringthe formation of the last stitch to depress the button-hole cutter to cut a slit in the Work, as the needle rises on ,the last up-stroke, means operativepthereafter to retract said button-hole cutter; a releasable connection between saidbutton-hole cutter and said work clamp raising means, means for releasing the connectionwhen the machineis started, means for re-establishing the connection only when the button-hole cutter s: depr s e a d: m ans .i onnectin vihelslamn r n m s {and h tr m said re ea able connection afterthe bu'ttpn-hole' cutter is ,de pressed being operative only during the last part ofthe rise: of the cutter'to transmit force: derived.

from the cutter retracting means-directly to the clamp raising means and-acting through said last named'means to move the trimmer to-sever;

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