US2437052A - Thread-controller for sewing machines - Google Patents

Description

March 2, 1948.

E. P. SPAINE THREADCONTROLLER FOR SEWING MACHINES Filed May 18, 1946 7 Sheets-Sheet 1 Edwwi'd Spa/inc,

March 2, 1948. E. P-. SPAI'NE THREAD-CONTROLLER FOR SEWING MACHINES Filed may 18, 1946 7 sheets-sheet'z Edward P 15 pain/ March 2, 1948. E. P. SPAINE 2, ,0

v I THREAD-CONTROLLER FOR SEWING MACHINES Filed May 1a, 1946 7 Sheets-Sheet 4 ilnv wrw Edward I? Spmine,

March 2, 194 -8.

E. P. SPAINE THREAD-CONTROLLER FOR SEWING MACHINES Filed May 18,.1946

7 Sheets-Sheet 5 DWELLING AT UPPER END OF 5720K:

THREA DEB LOOPE NEEDLE A T LOWE? END OF 5 TPOK E @iward P Spazlne March 2, 1948-. E. P. SPAINE' THREAD-CONTROLLER FOR SEWING MACHINES Fi l-ed May 18, 1946 7 Shee'bS She et 6 Edward P Patented Mar. 2, 1948 THREAD-CONTROLLER FOR SEWING MACHINES Edward P. Spaine, Bridgeport, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. J a corporation of New Jersey Application May 18, 1946, Serial No. 670,801

9 Claims.

1 This invention relates to sewing machines and particularly to the means for manipulating and controlling the under thread of a two-thread sewing machine during the stitch-forming cycle .in order that the under thread will not be subusual purl can be accurately positioned relatively to the buttonhole slit, second, a better threadluster on the finished buttonhole can be assured due to the absence of excessive thread-tension during the critical periods of stitch-formation, third, poorer grades of cotton needle threads can be used because of the fact that the various loops of one of the sewing threads formed about the other sewing thread during the concatenation of the threads are not prematurely closed and consequently do not effect a "choking action on the thread and, fourth, a very heavy looper thread can be employed because of the ready and proper yielding of the accurately controlled and lightly tensioned looper thread, which heavy looper thread can be used to good advantage in the production of so-called imitation hand buttonholes.

I accomplish this object by providing a threadcontrolling means properly located and timed with respect to the movable thread-carrying looper as to differentially modify the action of the looper on the thread to the extent that, during the entire stitch-forming cycle, the looper thread is subjected to a uniform light tension or control essential to the successful high speed operation of a two-thread chain-stitch buttonhole sewing machine.

In buttonhole sewing machines of the type herein illustrated, the under or looper thread mechanism is usually supported on a rotary turret situated beneath the work, the under thread mechanism including an oscillatory thread-carrying looper and complemental loop-retainers which are actuated by a reciprocatory hollow driving bar. The looper thread, in its passage from its source of supply to the looper, travels through the hollow loop-retainer driving bar and then to the heel of the thread-carrying loo-per.

The hollow reciprocatory loop-retainer driving,

bar and the oscillatory looper efiect a varying take-up action or control on the looper thread during each stitch-forming cycle, This control 2- is inadequate for successful operation of the stitch-forming devices.

In the present embodiment of my invention I have shown a preferred construction in which an additional thread-controlling element is fastened to the reciprocatory loop-retainer driving bar; said thread-controlling element being disposed to engage the loo-per thread between the threaddelivery end of the loop-retainer driving bar and the heel of the oscillatory looper. The position of the additional thread-controlling element relative to the loop-retainer driving bar and the heel of the looper is such as to combine its takeup action with that of the loop-retainer driving bar and the looper additively during a portion of a, stitch-forming cycle and subtractively during another portion of the cycle. As a net result, the three movable elements insure the desired yielding of the looper thread at the required times and the desired take-up action on the thread in compl ting a stitch at the right times, without leaving any uncontrolled slack in the thread at any time.

For the practical operation of a two-thread sewing machine, it is necessary also that an accurate control of the needle-thread be exercised. To that end, the machine illustrated is equipped with a cam-actuated take-up constructed substantially in accordance with the disclosure in my.U. S. Patent No. 2,165,016, dated July 4, 1939,

In order to give a complete understanding of the present 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.

Fig. 1 'is a right side elevational view of a buttonhole machine embodying the invention.

Fig. 2 is an elevational view of the looper thread stitch-by-stitch pull-01f mechanism employed for drawing from the looper thread supply a length of thread sufl'icient to complete each stitch, the thread arm being shown in full lines in its maximum pull-oil position and in dotted lines in its retracted position.

Fig. 3 is a front end elevational view of the machine shown partly in section.

Fig, 4 is a longitudinal vertical sectional view of the looper thread mechanism, showing the details of the actuating connections therefor.

Fig. 5 is an enlarged horizontal sectional view taken substantially along the line 55, Fig. 4.

Fig. 6 is a top plan view of the needle thread take-up device, with the top cover plate broken away to more clearly show the development of the actuating cam.

Fi 7 is a fragmentary View of a portion of a buttonhole, illustrating the way in which the purl-concatenations are uniformly and. tightly set close to the buttonhole slit.

Fig. 8 is a View, partly in section, of the stitchforming mechanism, showing several stitches completely formed in a fragment of work held in the work-clamp and the components of the stitch-forming mechanism and the sewing threads in position to begin the formation of the next stitch.

Fig. 9 is a front elevation of the turret with the work-clamp and needle-throat member in section, showing the stitch-forming mechanism components and sewing threads in position at the commencement of a stitch-forming cycle.

Fig. 10 is a right side elevation of the turret with the needle-throat member in section, showing the first step in the stitch-forming cycle in which the needle has descended to begin the slitstitch and entered the spread loop of needle thread detained by the right hand loop-retainer.

Fig. 11 illustrates the stitch-forming devices in their next position of stitch-formation, the detained needle-thread-loop having been released by the right hand loop-retainer and the threadcarrying looper having advanced and entered the next needle-thread-loop cast out by the ascending needle.

Fig. 12 is a front elevation, partly in section, of the parts shown in Fig. 11.

Fig. 13 shows the next position of stitch-formation in which the thread-carrying looper has traveled to the end of its needle-thread-loopseizing stroke and in so doing has positioned a limb of its own thread for seizure by the advancing left hand loop-retainer.

Fig. 14 is a front elevation, partly in section, of the parts shown in Fig. 13.

Fig. 15 shows the position of the stitch-forming devices at substantially the completion of the slit-stitch, in which position the looper-threadloop is detained on the left hand loop-retainer.

Fig. 16 is a front elevation, partly in section, of the parts shown in Fig. 15.

Fig. 17 shows the next position of stitch-formation in which the needle has penetrated the work to form the depth-stitch and has entered the looper-thread-loop held spread by the left hand loop-retainer.

Fig. 18 is a front elevation, partly in section, of the parts shown in Fig. 17.

Fig. 19 shows the needle at the bottom of its depth-stitch stroke, the looper-thread-loop having been released by the left hand loop-retainer and the loop being taken up by the retracting thread-carrying looper and my improved threadcontroller.

Fig. 20 is a front elevation, partly in section, of the parts shown in Fig. 19.

Fig. 21 illustrates the parts in the position after the non-threaded looper has seized the needlethread-loop cast out by the needle and Presented said seized loop for engagement by the advancing right hand loop-retainer.

Fig. 22 is a front elevation, partly in section, of the parts shown in Fig. 21.

Fig. 23 is a rear elevational View of the turret, showing the details of the looper oscillating connections.

Fig. 24 is a left side elevational view of the turret.

Fig. 25 is a top plan view of the turret; with the shank of the needle-throat-member in section and the remainder of the needle-throat-member shown in dotted lines.

Fig. 26 is a development showing the action of the needle, needle-thread take-up, thread-carrying looper and my thread controller on the two sewing threads during the complete stitch-forming cycle covering 720 degrees rotation of the arm-shaft of the sewing machine.

Referring in detail to the accompanying drawings, the invention is shown as embodied in a machine of the buttonhole type having, in general, constructive features which are substantially in accordance with the disclosure of the U. S. patent to Allen, No. 15,324, reissued April 4, 1922. The machine-frame is formed with a hollow box-like bed 3%) from the rear end of which rises a standard 31 of an overhanging bracketarm 32 terminating in a head 33. Supported on the bed 32 is the usual traveling work-holder comprising the lower work-supporting plates 34 and the upper clamping members 35, to which workholder longitudinal feeding and sidewise shifting movements are imparted for spacing the stitches of a buttonhole. The work-holder is moved relative to the stitch-forming mechanism during the sewing period as well as prior and subsequent to the sewing period by the usual connections with the feed-wheel 3%, as disclosed in said Allen reissued Patent No. 15,324.

The stitch-forming mechanism is constructed substantially in accordance with the disclosure of the Allen et al. Patent No. 1,372,473, dated Mar. 22, 1921. It is driven by means including a main sewing shaft 31, Fig. 1, journaled within and lengthwise of the bed 39, which main shaft 37, through one-to-one bevel gears 38, 3!), drives a vertical shaft Ml journaled within the standard 3!. The shaft 4t has a one-to-two speed-multiplying bevel-gear driving connection 4|, 42 with an upper or needle-bar-reciprocating shaft 43 which is journaled within and extends lengthwise of the bracket-arm 32 and has the usual crank M and link-connection 45 with a vertically reciprocatory hollow needle-bar 55 mounted in the head 33.

The hollow needle-bar 46, Figs. 1 and 3, has fixed to its lower end a yoke 31 carrying a crosspin id on which is slidably mounted a needleclamp-block 49 and embracing at its upper end the horizontal portion of the yoke 47. The block 49 carries an eye-pointed thread carrying needle 50. During its reciprocation, the yoke 41 is steadied by a vertical guide-member 55 depending from the lower end of a needle-bar bearing bushing 52 journaled in the head 33 and having a pinion 53 fixed to its upper end, whereby turning movements may be imparted to it, as in stitching around the eyelet-end of a buttonhole. As fully explained in the Allen et al. Patent No. 1,372,473, the needl-clamp-block 49 is adapted to be laterally vibrated on the cross-pin 49 through suitable connections with an internally grooved ringmember 5-? fixed to the lower end of a vertical slide-rod 55, Fig. 1, journaled in the head 33. The slide-rod 55 is reciprocated by means of. a link 55 adjustably and pivotally secured to the slotted limb of a bell-crank lever 51 fulcrumed at 53 on the head 33. The other limb of the bellcrank lever 51 is connected by a. link 58 to an arm 5%! fulcrumed at its rear end on the bracketarm 32 and actuated by an eccentric fast on the vertical shaft 40, in a manner fully disclosed in the above mentioned Allen et al. Patent No. 1,372,473.

Cooperating with the endwise reciprocatory and laterally shiftable needle 50, in the formation of stitches, are under thread-handling implements supported in the usual manner on a rotary turret Blhaving a.tubular shank 62 journaled in a vertical bearing aperture 63, Fig. 4, in a frameblock 64 detachably secured to the machine-bed 30. Extending upwardly from the turret 6| is a post 65 into the upper extremity of which is threaded a horizontal pivot-screw66 on which is fulcrumed a looper-carrier 61 formed with oppositely extending arms to which are rigidly secured the threaded and non-threaded loopers 56 and 69. The threaded looper .68 is provided adjacent its point or beak with a thread-eye I6 and in its heel with a pair of thread-eyes II and 12. The non-threaded looper 69 is formed with a loop-seizing beak 13 at the opposite sides of the base of which are formed loop-arresting shoulders T4.

The actuating connections for the loopers 68 and 59 comprise a link I secured at its upper end to one arm of the looper-carrier 61, Figs. 23 and 24, and at its lower end to the offset head '16 formed on the upper end of a tubular rod If, Fig. 4, fitted to slide within the tubular shank 52 of the turret 6i. At its lower end the tubular rod TI is formed with a circumferential groove 78 which is entered by the forked extremity of an arm I9, Fig. 3, clamped on a guide-rod 85 journaled to slide vertically in bearing lugs provided on the frame-block 64. The arm I9 is thus adapted to lift and lower the tubular rod 1'! and thereby rock the looper-carrier 61 about its fulcrum-stud 65. The means for raising and lowering the arm 19 preferably includes a link 8|,

Figs. 3 and 4, connected at its lower end to a crank 82 carried on the forward end of a short shaft 83 journaled in the frame-block 64. At

its inner end, the shaft 83 carries a pinion84 meshing with a gear 85 of triple its size supported by a stud 86 carried by the frame-block 64. Secured to the rear face of the gear 85 is a starwheel 87 which has imparted to it step-by-step turning movements by means of a pair of driving pins 83 arranged diametrically of a driving disk 59 secured to the main sewing shaft 31. As fully explained in the above mentioned '0. S. Patent No. 1,372,473, the teeth of the star-wheel 81 are shaped such wise as to produce periods of appreciable dwell between the periods of motion of the star-wheel. During these periods of dwell the crank 82 is held stationary at one or the other of its positions midway between its extreme up and down positions, thus arresting the motion of the loopers midway between the extremes of their strokes to avoid interference with the loopretainers now to be described.

Cooperating with the threaded looper 68 is a loop-retainer 90 hereinafter referred to as the right hand loop-retainer. As shownin Figs. 4, 10, 23 and 25, the right hand loop-retainer 90 is mounted on a carrier-lever 9I fulcrumed to oscillate about a horizontal pin 92 supported at its opposite ends by the spaced vertical posts 93 extending upwardly from the turret BI. At its free end the right hand loop-retainer 90 is formed with a curved and pointed loop-seizing horn 94 which, as will be explained later, functions to enter and retain control of a needle-thread-loop presented to the loop-retainer by the nonthreaded looper 69. overlying the horn 94 is a curved pilot 9 3 which functions to deflect the looper thread above the horn 94 when the loopretainer 90 is advancing to enter the needlefulcrumed on the horizontal pin 92. Like the first loop-retainer 90, the second loop-retainer 95 is formed at its free end with a curved and pointed loop-seizing horn 91. The two 10op- re tainers 90 and 95 are oscillated on their common fulcrum-pin 92 by means including two links 90' and 99, Fig. 4, connected at their upper ends to the carrier-levers 9| and 96 and at their lower ends to the opposite ends of a cross-head I00.

The cross-head I00 is preferably integral with the upper end of a rod IOI bored longitudinally to provide a looper-thread passagewa I02. The rod IN is slidingly fitted within the tubular rod TI and has clamped to its lower end two collars I03 and I04 spaced to provide a circumferential groove I05 adapted to receive the forked extremity of an actuator arm I06 projecting forwardly from a slide-plate I 01 fitted to a slideway I90 in th transverse bed-partition I09. The slideplate is caused to reciprocate in the slideway I06 by a roller IIO carried by the slide-plate and tracking a suitable cam-groove III cut in the rear face of the driving disk 89. Through the connections just described it will be understood that rotation of the main sewing shaft 31 causes the driving disk 89, through the star-wheel 81, to impart to the threaded and non-threaded loopers 68 and 69 a variable motion and at the same time, through the cam-groove I I I, to actuate the right and left hand loop-retainers and in proper sequence to effect stitch-formation;

To properly support the work W at the stitching point, there is provided the usual needlethroat-meinber or button I I2 apertured at its upper free end, as at II3, to provide needle-clearance, and adjustably supported at its lower end on a, vertical post II4 integral with the turret GI. The needle-throat-member II2, when correctly mounted, lies directly above and very close to the path of movement of the retainer- horns 94 and 91 which, it will be seen, operate at an elevation between the loopers 68 and 69 and the throat-member II2.

The mechanism for turning the stitch-forming mechanism in stitching around the eyelet-end of a buttonhole is constructed substantially in accordance with the disclosure in the E. E. Allen Patent No. 1,162,207, Nov. 30, 1915. Suffice it to say that the needle-bar mechanism carries a gear 53,-Figs. 1 and 4, and the turret carries a similar gear II5, these gears having in mesh therewith tWdgear-segments H6 and II! connected together by mechanism deriving its actuation from the feed-wheel 36. 4

To control the needle thread N the present machine has mounted on top of the bracket-arm 32 a common form of thread take-up mechanism disclosed, for instance, in my U. S. Patent No. 2,165,016, July 4, 1939. The take-up mechanism includes a housing IIB, Figs. 1 and 6, enclosing a take-up cam II9 which is mounted on a shaft I20 gear-driven by the needle-bar reciprocating shaft 43. Pivotally mounted at I2I, Fig. 6, in the housing I I8 is a take-up lever I22 carrying intermediate its ends a follower roll I23 which enters the take-up cam-groove I24. The take-up lever I22 has at its free end a thread-eye I25 which acts upon the needle thread N between a conventional tension device I26 and the hollow needle-bar 46 through which the needle thread runs to the needle 50. As shown in Figs. 1 and 6, the needle thread N travels from a source of 7. supply through aguide hole (not shown)" in: a post I21, thence between the disks oi the tension device i253, thence up throughafixed threadeye He in one limb of a-u -shaped plata 1 2a fast on the housing cover-plate I-30 andthen down through a fixed thread-eye lz'il in the other limb of the-plate F29 and throughthetake up thread eye I253 thence forwardly" through the open thread-nipper E32 and down through the hollow needle-bar 46 into the thread-retainer I33, Fig. 3,- and then to the needle 59. It will be appreelated that for perfectstitch-formation an accurate control of the needle thread must be maintained and that the control exercised must bear a definite relation: to that applied to the looper thread. Sucha control of n'eedle'thread is accomplished with the aid of the: take-up camgroove 24 which is preferably cut to operatethe take-up lever 522 so that its. thread require-- ments areas indicated in Fig; 26.

The course: of travelv of the looper thread L is best shown inFigs. l, 2rand S. From-asupply the looper. thread passes through' a guide-tube I3 1, thence through-a thread-eye I35 providedin the free end-portion of athread pull off lever I36 frictionally fulcrume'd at I31 on the bed 30: The thread pull-off lever I36. is: oscillated about its fulcrum I31 from the dotted lineposition to the full line position, Fig 2, by the alternate-em gagement of-the spacedarmsltd and I-39'by the two pins use and Hi! carried on adisk I42-fast on a cross-shaft I43, in a manner: fully shown in U. S. Patent No. 2,210,638, Aug. 6; 1940. 'One complete stroke is imparted tothe threadipulbofi lever I 36 during the complete. buttonholing. cycle, thelength of slack looper thread thus provided being suflicient to complete thestitching cycle.

From the thread-eye I35; the looper thread runsthrough a guide-hole Hi4, Figs. 2 an'd3,-in the bed 38, thencethrough a self-threading wire thread-guide M5 to and through the regular tension device I58, and thenup' through the bore I02 of the loop-retainer actuating rod H. In prior machines it has been customary: to lead the looper thread L directly from theupper end of the hollow rod H to and through thethreadeyes in the threaded looper 68.- The threadcontrolling action-obtained by the reciprocatory loop-retainer driving bar mland the oscillatory looper 68 only approximated that required and,

to resilient check-springs and other similar devices had to be employed. Thesedevices improved the thread-handling to some extent; but were not entirely satisfactory. V

The present invention contemplates the use of a thread-controller, indicated generally as-G, disposed to operate on the looper thread-asit passes from the upper end of the loop-retainer driving bar IM to the heel of the thread-carryinglooper- E8. The improved thread-controller is adapted to be carried by the loop-retainer driving; bar IM and therefore partakes of the vertical reciprocation thereof. The resultant movement of-the controller working in conjunction with the oscil 7 latory thread-carrying looper 63' and withother of the movable elements of the under thread handling mechanism forms a bight in the looperthread which varies in size. The effect of this varying nightis a control of the looper thread L such that the thread is devoid of excessive rier-leverlink 99 to the cross-head I00, .is fornied satisfactorily handle the looper thread,-

8 with an: extension M1 on which is adi-ustably clamped by means of ascrew I48 the lower end of the shank I 49 or my" improved looper-threadcontroller. Attheupper end, the shank I49 terminates in an onset head I50 formedwitn a vertically disposed aperture I5I, Fig. 13-, intersected by aslot I52 cut in the top face of the oifse't' head I'5El,.the aperture and slot providing a thread-eye through which the looper thread travels. To facilitate threading the aperture I5I,

illustrated form of thread-controller mounting also provides for allowing a small degree ofoilcular adjustment ofthe controller-element about the axis of the extension I41.

To aid-indescribing a cycle of operations of the stitch-forming mechanism,- attention is directed to Figs. 8 through-22,- inclusive. Letit be understood thatin the present case: a complete stitch-forming cycle includes two complete reciprocations of the needle, the cycle beginning with the needle in raised position preparatory to descendingtoformthe so-called slit-stitch. Since two reciprocations of the needle are included-in the complete stitch-forming cycle, thearm-shaft t3 rotates through 720' degrees. With this in l mind; assume now that the machine has produced several stitches and that the parts are in the positionshown inFigs;- 8 and 9, with a 1001) I56 of needle thread detained and held' spread on the horn 94 of the right hand loop-retainer 9i), and

=with the thread-carrying looper 68 in a position of dwell awaiting the descent of the needle 52 to begin the slit-stitch. Withthe parts in these positions, the'thread-controllerC isalso in a state of dwell-since it is mounted on'the loop-retainer driving rod- Iill which, as mentionedab-ove, is stationary at this time. Continuing withthe cycle; the needle 56 now descends through the work W and enters the=needle-thr'ead-loop I5=l detained by the horn it of the right hand-locoretainer 1% (Fig. 10). During the descent of the needle fib towardthe work -W, the needle threadtake-up lever I22 isa-ctuated'in a direction to absorb the slack in the needle 'threa'd'i'iroduced by. the descending needle-bar. when the needlepoint-penetrates the work, the needle thread take needle-thread-loop I541 about the needle 53, as shown inFig; l1. Then-eedle 5i! then-travels-to thehottom :01" its stroke, after-which it begins to ascend, l casting out the needle-thread-loop I55 which isenteredby the advancing thread-carry- !56', Fig. 10, the righthand-retainer til-is retracted, leaving the 9 ing looper 68, as shown in Figs. 11 and 12. As the looper 68 passes the needle 59 in its loopseizing stroke, the needle thread take-up lever I22 is operated to take up a slight amount of thread to partially close the cast-out needlethread-loop I55, thereby preventing said loop I55 from twisting in a direction away from the beak of the looper 68 and also to provide a purchase on the needle-thread enabling the needle-bar better to work in drawing up the preceding needlethread-loop I54 to the inside edge of the purl formation. After the looper 68 enters the cast out needle-thread-loop I55, the needle 55 is withdrawn from the work and the looper 53 continues in its advance until it reaches the end of its loopseizing stroke, Figs. 13 and 14.

During the movement of the parts from the positions shown in Fig. 11 to the positions shown in Fig. 14, the thread-controller C moves upwardly to assist in giving some slack looper thread to the advancing thread-carrying 1ooper 68. But, near the end of theadvancing stroke of the looper 68, a sufficient bight is formed in the looper thread (Fig. 14) to effect a control action on the looper thread. This control action results in a straightening of the limb I56 of looper thread extending from the thread-eye I in the looper 53 to the previous stitch in the work (Fig. 14), thus positioning the limb I55 across the path of movement of the loop-retainer 95 so that the horn 91 of the loop-retainer unerringly seizes said'thread-limb I55. After seizure of the looper-thread-limb I55 by the left hand loop-retainer 95 (Figs. 13 and 14), the continued upward movement of the threadcontroller C and the bodily upward movement of the loop-retainer driving bar I flI provide slack looper thread for the formation of the looperthread-loop I! (Figs. 15 and 16) which is detained by the horn 91 of the left hand loop-retainer 95 after the thread-carrying'looper 98 has retracted far enough to release the needle-threadloop I55. Continued retraction of the threadcarrying looper 69 provides additional slack looper thread, which slack thread is augmented slightly by the continued upward movement of the thread-controller C so that sufficient tension-free looper thread is furnished to permit the needlethread-loop I55, cast off by the looper 68, to be pulled up in response to the needle thread takeup action, to the purl-forming position at the under side of the work, as shown in Fig. 16. As the needle-thread-loop I55 is pulled up to its purl-forming position, it carries with it the looper thread forming the thread-loop I5! (Fig. 16). The amount of looper thread made available by the thread-controller and the thread-carrying looper 59 is sufiicient so that when the needlethrea-d loop I55 is pulled up to purl-forming position, the looper-thread-loop I51 on the horn 9'! of the left hand loop-retainer 95 is caused to slide up the horn into the throat thereof '(Fig. 15) thus opening or spreading the looper-thread-loop I5! for positive entrance by thedescending needle 55 on its next work-penetrating stroke, as shown in Figs. 17 and 18. It is desirable that the looper thread be properly controlled at this critical time vin the cycle, for if the looper thread is undercontrolled and there is too much slack looper thread the thread-loop I5! on the loop-retainer horn 91' will not be drawn up into the throat of the horn. Consequently, the thread-loop I51 will not be spread suiiiciently to insure the unerring entrance thereof by the needle. Further, if the looper thread is over-controlled at this time, the thread will be excessively tensioned and therefore the thread-loop I51 will not cast free of the loop-retainer horn 91 at the correct instant, but will hang on the horn causing either a stealing of looper thread from the supply or a pulling down of the previous needle-thread-loop I55 from its purl-forming position. This pulled down or displaced needle-thread-loop I55 must be reset. This resetting however cannot always be accomplished and particularly when the pull on the thread, resulting in the displacement of the previous needle-thread-loop I55, has closed or tightened any of the previous unset thread-loops. Later in the stitch forming cycle, the failure in resetting the needle-thread-loop I55 into its normal purl-forming position up against the under side of the work (Figs. 21 and 22) will result in lowering the lead of that portion of the looper thread L extending from the needle-thread-loop I55 to the looper-thread-eye 10, to a position below the level of the point of the pilot 94' on the advancing right hand loop-retainer 99. Should this occur, the looper thread will be engaged by the advancing loop-retainer 99 and pushed to an abnormal position, i. e. from one side to the other side of the needle 59. This causes an abnormal concatenation of the sewing threads and results in a malformed or rough purl.

When the needle-thread-loop I55 has been properly pulled up to purl-forming position and the looper-thread-loop I5'I is-detained on the horn 91' of the left hand loop-retainer 95 (Fig. 16) the thread-controller C is positioned at the top of its stroke. The needle 59 now descends to start the depth or bight stitch, penetrating the work W and entering the looper-thread-loop I51, as shown in Figs. 17 and 18. After the needle 59 has entered the looper-thread-loop I51, the left hand'loop-retainer 95 is retracted, causing the horn 97 thereof to shed the loop I51 on the needle 50. The needle then continues to the bottom of its stroke and begins its ascent to cast out a needle-thread-loop I 58. The nonthreaded looper 69 now advances in the direction indicated by the arrow in Fig. 20, to seize the needle-thread-loop I58 cast out by the needle. After seizure of the thread-loop I58 by the beak 13 of the non-threaded looper 59, the needle 59 is withdrawn from the work W and the nonthreaded looper 69 carries the needle-threadloop I58 to the right as shown in Fig. 22, thereby to position it for entrance by the horn 94 of the right hand loop-retainer 99. During the movement of the parts from the position shown in Fig. 18 to the position shown in Fig. 22, the looper-thread-controller C moves downwardly and augments the take-up action of the threaded looper 58 and the loop-retainer driving bar IIlI to the extent of, first, properly reducing the looper-thread-loop I5! about the needle and,

second, of taking up the slack looper thread created by the retraction of the threaded-looper 58, whereby the lead of the looper-thread ex tending from the needle-thread-loop I55 to the looper-thread-eye III (Fig. 22) will be above the advancing point of the pilot 94 on the loopretainer 95. By maintaining the lead of the looper thread above the point of the advancing pilot'94, the looper thread will be directed over the top of the loop-retainer during each stitchforming cycle, thus insuring a uniform positioning of the looper thread to the left of the needle as viewed in Fig. 10. This constant relative disposition of looper thread with respect to the needle insures a uniform concatenation of the threads forming the purl.

After the; right hand loop-retainer 963,- has entered andv seized: the needle-thread-loop tad presentedv by the non-threaded looper 69,, the latter is-lretractedi from its advanced position. shown in Fig; 22-: to; an, intermediate; dwell position: shown in Fig; 9. Thev thread-carrying looper; 68 has advanced to its: intermediate dwell, position in readiness for, the descent of. the, needle to start the next slit-stitch; The complete stitche-iorming'cycle, has. now been performed.

While Ihave not. described in detail the action the. needle; thread of the take-up lever I22, it will be: understood that accurate control of the; needle. thread is. essential. This control is illustrated: in Fig. 25,.whi'ch discloses a diagram or: dvelopment ofthe displacement of the. needle fillpandg looper 63, the, thread-control of the needle thread takeeup. andthe control produced by the thread-controller C; The positions lengthwise of the diagram indicated by the vertically disposedarrows and numerals 8 to 22', inclusive, correspond respectively, with the periods of the stltcheformin'g cycle shown in Figs. 3 to 22, inelusive;

From the above. description, it will be evident that the exacting thread-control made possible by my improved controller renders the machine capable of producing buttonholes of highest quality; One of'the factors contributing to this is'the uniform formation of the purl close to and paralleling the slit of the buttonhole. While a uniform formation and location of the purl has beenheretoforeattained in buttonhole machines, this was: accomplished by using hard finished cords ot'good size in combination with a strong tension, causing the purl to roll toward the slit. This method proved successful on material of a firm weave, but not so successful on material of a flimsy nature, such as cottons having a basket or diagonalweave. The present improvement has: adapted the machine for sewing equally well onfirm or flimsy weave materials. It is further desirablethatthe maximum degree of lustrebe preserved on. the sewing threads in the finished button-hole. It is well known that the thread lustre is reduced when the thread is excessively tensioned In prior machines the thread-control was at best an approximation and as a result thereof'the loops of thread during stitch-forms. tion were unavoidably prematurely closed. This choking of the thread-loops had to be overcome lay-excessively tensioning the threads, causing not only a reduction in the lustre of the completed buttonhole but minimizing the ability of the machine tohandle successfully the poorer I. A two-thread sewing machine having work- H holding means" and stitch-forming mechanism which are relatively movable to space stitches, saidstitch -formingmechanism including an endwisev reciprocatory and laterally'vibratory threadcarrying needle, a threaded looper and a non- 1'2 threaded looper adapted: alternatelyto ent thread-loops presented by said needle, loop-retainers, for seizing: thread-loops from; said loopers and presenting themior entrancegby'said needle, means for. actuating saidl stitch-forming mechanism. including a driving bar operatively connected to said. loop-retainers, thread-guiding means carried, by said driving bar for directin thread to said threadedlooper, and a threadcontroller adapted to engage. the thread between said thread-guiding means and? said threaded looper,

2. A two-thread sewing machinehaving workholding means and, stitch-forming mechanism which are relatively-movableto spacevstitches, said stitch-forming mechanismv including an. endwisc reciprocatory and laterally'vibratory thIGHJdrCEY- rying needle, a threaded. looperand a nonthreaded looper adapted alternately to enter thread-loopspresented by said'needle, loop-retainers for seizing thread-loops; from. said. loopers and presenting them. forxentrance by said: needle, means: for actuating said stitch-forming mechanism including a. reciprocatory driving bar operatively connected-.to-saidloop-retainers, threadguiding means carried bysaid drivingabar for'directing thread to said threaded looper, and a thread controller movable in a right line parallel to-the axis of said driving bar and disposed toengage; the thread between, said thread-guiding means and said threaded-looper.

3. A two thread sewing machine having workholding means and stitch-forming mechanism which are relativelymovableto, space stitches, said stitch-fo'rming mechanism including an endwise reciprocatory and laterallyvibratorythreadcarrying needle, a threaded looper and a nonthreaded looper adapted alternately to enter threaddoops. presented by said needle, loop-retainers for seizing thread-loops from said loopers and presenting them for: entrance b said needle, means for actuating said stitch-forming mechanism including a. driving bar operatively connected to said loop-retainers, thread-guiding means carried. by said driving bar for directing thread to said threaded looper, and a threadcontroller mounted on said driving. bar and adapted to engage the; thread between said threa'd' guiding means and said threaded looper.

4. A two-thread sewing machine having workholding' means and stitch-forming mechanism which are relatively movable to space stitches, said stitch-forming mechanism including. an endwise reciprocatory andlaterally vibratory threadcarrying needle, a. threaded looper and a nonthreaded loloper' adapted: alternately to enter thread-loops presented by said needle, loop-retainers for seizingthreadeloops from-said loopers and presenting them for entranceb said needle, means for actuating-said stitch-forming mechanism including an endwise reciprocatory driving bar operativelyconnected to. said: loop-retainers and having a looper, thread-guiding boreterminating at the end of saidbar adjacenttsaid loop-retainers, and. a thread-controller'mounted on said driving bar and adaptedto engage the threadbatween said tin'ead-guidingbore andsaid threaded looper;

5. A two-thread sewing machine having workholding means and stitch-forming mechanism which are relatively movable to space stitches, said stitch forming mechanism including an endwi'se reciprocatory and laterally vibratory threadcarrying needle, means. for varyingthe amplitude of vibration of said needle, threaded? nonthreaded loopers adapted alternatel to enter thread-loops presented by said needle, loop-retainers for seizing thread-loops from said loopers and presenting them for entrance by said needle, means for actuating said stitch-forming mechanism including a driving bar operatively connected to said loop-retainers, thread-guiding means carried by said driving bar for directing thread to said threaded looper, a thread-controller adapted to engage the thread between said thread-guiding mean and said threaded looper, and. means supporting said thread-contrller for varying the operative location thereof in accordance with the selected amplitude of vibration of said needle.

6. A two-thread sewing machine having workholding means and stitch-forming mechanism which are relatively movable to space stitches, said stitch forming mechanism including an endwise reciprocatory and laterally vibratory threadcarrying needle, mean for varying the amplitude of Vibration of said needle, threaded and nonthreaded loopers adapted alternately to enter thread-loops presented by said needle, loop-retainers for seizing thread-loops from said loopers and presenting them for entrance by said needle, means for actuating said stitch-forming mechanism including a driving bar operatively connected to said loop-retainers, thread-guiding means carried by said driving bar for directing thread to said threaded looper, a thread-controller adapted to engage the thread between said thread-guiding means and said threaded looper, and means supporting said thread-controller and permitting adjustment of the operative location thereof in a direction parallel to the plane of viv mechanism including a member having a variable reciprocatory motion operatively connected to said loop-retainers, thread-guiding means carried by said member for directing thread to said threaded looper, and a thread-controller adapted to act on the thread between said guiding means and said threaded looper and movable in a path parallel to the line of reciprocation of and in synchronism with said member.

8. A two-thread sewing machine having workholding means and stitch-forming mechanism which are relatively movable to space stitches, said stitch-forming mechanism including an endwise reciprocatory and laterally vibratory threadcarrying needle, oscillatory threaded and nonthreaded loopers adapted alternately to enter thread-loops presented by said needle, loop-retainers for seizing thread-loops from said loopers and presenting them for entrance by said needle, means for actuating said stitch-forming mechanism including a reciprocatory driving bar operatively connected at one end to said loop-retainers and having a thread-guiding bore extending from one end to the other for directing thread to said threaded looper, and a threadcontroller secured to said driving bar and having a thread-engaging free end disposed to act on the thread between the mouth of said threadguiding bore and said threaded looper.

9. A sewing machine having, in combination, an endwise reciprocatory and laterally jogging thread-acrrying needle, oscillatory threaded and non-threaded loopers cooperating with said needle in entering thread-loops presented by said needle, a plurality of loop-detainers for seizing thread-loops from said loopers, means for actuating said loop-detainers including a driving member operable in a right line, thread-guiding means carried by said driving member for directing thread to said threaded looper, and a threadcontroller operable in a right line and disposed to act on the looper thread between said threadguiding means and said oscillatory threaded looper, said thread-guidin means, oscillatory threaded looper and thread-controller summarily effecting a differential control on the looper thread such that the latter is devoid of excessive strains during the entire stitch-forming cycle.

EDWARD P. SPAINE.

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