US1600207A - Buttonhole-sewing machine - Google Patents

Description

Sept 1925.

' E. a. ALLEN BUTTONHOLE SEWING MACHINE Oiiginal Filed July 5. 1923 9 s t 5 1 INVENTOR ATTORNEY Sept. 21 1926.

1923 9 shet sheet 2 Original Filed July 5.

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Sept. 21 1926.

E. B. ALLEN auwwonaom SEWING nmqmma o'rizinal Filed July 5. 1923 9 Sheets-51100125 7, III

INVENTOR flaw ATTbRhEY Sept. 21 1926.

E. B. ALLEN BUTTONHOLE SEWING MACHINE original Filed-Jul 5. 1923 9 sheetspsh 4 ATTORNEY Bi .QN s E ET x.

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Sept. 21 ,1926.

E. B. ALLEN BUTTONHODE SEWING MACHINE Original Filed July 5. 1925 9 Sheets-Sheet 5 ATTORNEY Sept. 21 1920.

E. B. ALLEN BUTTONHOLE SEWING MACK-II NE Orizinal Filed July 5.

9 Sheets-Shet 6 mm 0 "Hill Sept.v 21 1926. 1,600,207

E. B. ALLEN BUTTONHOLE SEWING MACHINE 9 Sheets-Sheet '7 Original Filed July 5. 1923 V n V N I INVENTOR WTNESS BY 7'! W. V v TTORNEY Sept. 21 1926. 1 E. B. ALL EN BUTTONHOLE SEWING MACHINE Original Filed July 5. 1923 9 Sheets-Sheet 8 ATTORNEY WITNES ES Sept. 21 ,1926. 1,600,207

I v E. B ALLEN BUTTONHOLE SEWING MACHINE Original Fil y 5. 1923 {Sheets-Sheet 9 Ml/ll/ 7 m I INVENTOR BY I Patented Sept. 21, I 1926'.

UNITED STATES PATENT OFFICE.

EDWARD IB. ALLEN, or NEw'rowN, coNNEorIcUr, AssIGNoE'ro THE SINGEEMANU- EAc'rUEING COMPANY, or ELIZABETH, NEW qEEsEY, A coEroEArIoN; OF NEW JERSEY.

Original application filed July 5, 1923, Serial No. 649,440. Divided and thisapplieation Serial No. 1,349.

This invention relates to automatic buttonhole sewing machines and has for an object to provide a high-speed machine particularly adapted forcloth work, whereby a maximum production of stitched buttonholes may be obtained with a minimum of effort on the part of the' operator; the buttonholes being finished when removed from the machine and requiring no subsequent hand trimming o rations. Another object of the invention 1s to provide the machine with an under thread and cord trimmer which is independent ofthe buttonhole cutting mechanism and hence applicable to machines'which cut the buttonhole either before or after the sewing period- Another object of the invention is to provide simplified means for freeing the under thread mechanism or loop-taker from the last needle-loop customarily retained thereby. Still fur-- ther, the invention has for an object to provide means for controlling'the position of the purl of the overlying stitches of a flyba-r buttonhole. Further objects of the in- 2 vention will appear from the following description and claims.

The machine of my copending application Serial No. 523,056, filed December 17, 1921, while of general application,- is intended more particularly for that class of trade to which the quality of the finished buttonholes is more important than the quantity of buttonholes produced per machine. The speed of the machine of my said copending application is limited because of the fact that it embodies stitch-forming mechanism of the so-called I. B. H. (improved buttonhole) I type wherein an upper reciprocating and laterally jogging needle makes two complete re- 40, ciprocations for each stitch-formin 'cycle. It is impracticable to operate stitchorming mechanism ofthis type at speeds easily. attained by stitch-forming mechanism of the H & H type representedin my; Patent No. 1,162,207, of November 30; 1915. In stitch-forming mechanism of the H & H

type,'a lower curved -slit=stitch needle cooperates withan upper straight depth-stitch needle; the latter making but one complete reciprocation per stitch-forming cycle.

The machine of my said Patent No. 1,162,-

BUTTONHOLE-SEWING MACI HINE.

filed January 207, is intended primarily for leather work, such as the sewing of a series of buttonholes in a shoe upper and, for this work, an under thread and cord trimmer is not required, as the buttonholesare stronger if the. cord bridges the spaces between the'buttonholes and extends in one continuous length throughout the series. When sewing button: holes in cloth, however, it is desirablethat the cord and sewing threads be trimmed close to the last stitch so that each individual buttonhole will have a finished appearance on both sides when removed from the machine and Will not have to be retrimmed by .65 hand.

i To the attainment of the ends in view I have reorganized the machine of my said cope-nding application, building into it stitch-forming mechanism of the upper straight needle and lower curved needle type. The under thread and cord-trimmer is arranged to be operated b a cam on the rapid feed-shaft of the mac inc and is independent of the buttonhole cutting mechanism. An upper thread trimmer is arranged to sever the needle-thread .at the end of the sewing period and means are provided for thereafter, shifting the work-holder away from the stitch-forming mechanism to draw the last needle-loop clear of the loop-takerv and also to draw off safe lengths of under thread and cord prior to the action of the under thread and cord-trimmer. The purl of the overlying stitches of a fiy-bar buttonhole is controlled by automatic mechanism operated by the rapid feed-shaft for increasing the tension on the under thread during the sewing of said overlying stitches, whereby the purl will be pulled over to the curved 9o needle punctures and give the finished 'buttonhole an even, flat and desirable appearance. The present invention further comprises the novel combinations of parts and details ofconstruction hereinafter described and particularly pointed out in the appended claims. I

x In the accompanying drawings, Fig. 1 is a right-side elevation of a buttonhole sewing machine embodying the invention; the 1 parts being in their respective positions oocupied when the machine is at rest. Fig.

2 is a left-side elevation of the machine.

- Fig. 3 is a front elevation of the machine with the work-supporting platesin section. Fig. 4 is a horizontal section through the bracket-arm standard of the machine and with the work-clamp removed to show in plan certain mechanism within the machine bed. Fig. 5 is a fragmentary rear end ele- Fig. 9 is a fragmentary front elevation showing in dotted and full lines theunder thread and cord-cutter in retracted and operative positions, respectively. Fig. 10 is a fragmentary plan View of the lower work-supporting plates of the work-clamp. Fig. 11

is a sectional view through the upper threadtension and its support. Fig. 12 is a fragmentary side elevation, partly in section, of the mechanism for increasing the tension of the under-thread tension device. Fig.- 13 is a detail erspective View of the underthread tension-modifying lever. Figs. 14 to 19 inclusive are views illustrating the relative positions of the parts adjacent the sewing point at different periods of 'a buttonhole-producing cycle. Fig. 20 is a plan view of the corded side of a finished buttonhole, as removed from the machine and Fig. 21 is a fragmentary elevation within the machine bed showing certain details of the clutch-controlling mechanism for the rapidfeed shaft.

As disclosed in my copending application Serial No. 649,440, filed July 5, 1923, of which this application is a division, the machine is constructed with a hollow frame comprising a hollow rectangular bed 1 from one end of which rises the standard 2 of the bracket-arm 3 terminating in the head 4. The stitch-forming mechanism is constructed substantially in accordance with the disclosure of my said Patent No. 1,162,207, and the curved needle I the latter carrying a loop of under thread through the loop of upper threadand over the edge of the buttonholeslit, positioning said under thread loop at the upper side of the work for entry by the upper needle in its next descent. Thus, the

upper needle makes but one complete reeiprocation for each stitch-forming cycle and the mechanism operates smoothly at speeds much higher than are practicable with stitch-forming mechanism of the I. B. H. type represented in my Patent No. 15,324, reissued April 4, 1922, and in the Allen & Faulkner Patent No. 1,372,473, of March 22, 1921.

The needle-bar 6 is connected as usual to be operated by the upper or needle-bar operating shaft 9 geared at 10 to be driven from the vertical shaft 11 at double the speed of the latter. The shaft 11 is geared at 12 to be driven by and at the same speed as the main sewing shaft 13.

The curved needle 7 and loop-taker 8 are mounted on the rotary turret 14 and are connectedin the usual manner, substantially as represented in said Allen & Crosby patent. to be operated by the looper-operating shaft 15 which is geared at 16 to be driven by the main sewing shaft 13 at double the speed of the latter. The needle-bar operating shaft 9 and the looper operating shaft 15 are thus driven at the same speed, .which is double the speed of the main sewing shaft 13. During the sewing, the needle-bar 6 and turret 14 are turned by the usual connections with the feed-wheel 17 to lay the stitches radially around the eyelet-end of thebuttonhole.

After the sewing is completed the-parts are reversely turned to initial position. The

needles operate through the crescent-shaped.

aperture in the usual needle-throat or button 18 carried by the turret 14; the button 18 being apertured as usual to guide the staycord 8.

The work-holder is of the usual construction substantially represented in my said reissued patent. It is adapted to move both laterally and longitudinally of the bed 1 to space the stitches around the buttonhole and to move the work relatively to the stitchforming mechanism intermediate sewing periods to carry the work from buttonhole cut-- ting position to sewing position and, in the present instance, from sewing position to thread-cutting position and back to initial or buttonhole cutting position. The workholder comprises the lower work-supporting plates19, separable to spread thebuttonhole and the upper clamping feet 20 whichare carried by the usual clamp-levers 21 opermatically to close the clamp by the roll 25 at.

the front end of the clamp-closing lever 26 fulcrumed at 27 on the frame member 2 and actuated through the usual latch-pin connection 28 with the continuously runningpulley 29, as described in my'said reissued The other of the connected rock-- patent.

shaft -sections"22,"Fig. 2, carriesthe leverarm which when pushed forwardly to the position shown in'Fig. 2, effects the opening of the work-clamp and the release of the work. I

- The work-holder is equipped with the usual clamp-spreading and unspreading toggle device 31, Fig; 4, and connections repre- 'sented in said reissued patent and includ ing the levers 32- and 33, which when pushed forwardl or toward the left, Fig. 4, respectively, effect the spreading and unspreading of the clamp. The Work-clamp-sections are mount edfas usual on the cross-slide plate 34 which, in turn, is inounte'd'on the'lon'gitudinal slide-frame 35. Y

The work-clamp derives the longitudinal "component of motion of the work-clamp is derived through the lever connection 36 "with the lateral feed-cam groove 37 in the readily accessible controlling wheel 38 mounted externally of the sewing machine frame, preferably at the side of the hollow bed 1, on the rapid feed-shaft 39 which carries thebevel-gear 40 meshing with a similar gear 41 on the feed-wheel 17. The present feeding mechanism is of substantially the same construction as that shown in my said reissued patent, except that the main feedwheel of the present machine has no lateral feed-cam groove; the lateral feed camgroove in the controlling wheel being used instead, throughout the buttonhole producing cycle. The connected feed- wheels 17 and 38 are driven at a slow speed during the sewing by means of suitable connections, such as represented in my said reissued patent, with the vertical shaft 11. Intermediate sewing operations the connected feed-wheels are driven at a higher speedby means of the rapid feed-shaft 39 which is connected through an automatically controlled clutchmechanism with the rapid-feed drive-shaft 42. The rapid-feed drive and automatic clutch control are of substantially the construction represented in my copending application Serial No. 537,381, filed February 18, 1922, and comprise the clutch 43, Fig. 6, and the continuously reciprocating clutch-' operating bars 44, 45, which are latched in their idle positions, Figs. 6 and 21, by means of the latches 46, 47. It will be understood, particularly from the disclosures of my said copending application, Serial No. 537,381, and my said reissued patent, that the release of the latch 47 permits the bar 45 to, operate the clutch 43 to connect the shaft 39 to the rapid-feed drive-shaft 42, thus throwing the rapid-feed mechanism into operation, and release of the latch 46 permits the bar 44 to operate the clutch to throw the rapid-feed mechanism out of operation. The throwshaft 56 and the latter beingelevated', as de-- out latch 46 forthe rapid-feed mechanism is connected to the lever 48, Fig. 21, which is operated by the trippingpoints 49 on the inner face of the controlling wheel 38. The rapid-feed throw-in latch 47 is-connected to an arm 50 on the 'rock-shaft'51 The shaft- 51 carries arms 5231K} 53, Fig. 1, the former being depressed by a cam 54' on the usualcl'utch-d'isk 55 fast to the buttonhole cutterscribed in said copending application, by

the vertical motion ofthe stopping tooth57 carried by the usual. stop-motion lever58 which controls the "connection of the. sewing shaft 13 with the constantlyrunning pul- The buttonhole cutting mechanism is substantially the same as that disclosed inmy said copending application Serial No. 537,-

381 and includes the usual cutter-levers .60,

61, Fig. v4, which are pivotally mounted at 62 on the travelling. fulcrum-block 63; the latter receiving its travelling movements from the link' connection 64 with the cutteradvancing and retracting cam 65 on the cutter-shaft 56. The cutter-shaft alsoicarriesthe usual cutter-lever closing cams 66, '67. The disk 55 on the cutter-shaft constitutes the driven member of the usual one-revolution clutch device, the operation of which-is controlled by movement of the usual cutterclutch controlling lever 68 mounted on the- Vertical fulcrum-pin 69., As explained in my said copending application Serial No.

537,381, clockwise movements of the lever 68, Fig. 4, effects the coupling of the cut ter-shaft 56 to the continuously rotating pulley 29 for one revolution after which the cutter-shaft is automatically uncoupled from ing the follower tooth 72 which bears upon 1 the controllin wheel 38. When the tooth 72 is engage by the cam incline 73, the stop-motion lever 58 is rocked clockwise, Fig. 2, to start the'stitch-forming mechanism ,which continues in operation until the declivity 7 4 passes the tooth 72, whereupon the spring 75 restores the stop-motion lever to stopplng position, Fig. 2, and thereby, arrests the action of the stitch-forming mechamsm. a

The machine is preferably equipped with means above the work for cutting and nipping the upper thread at the end of the sewr mg perio The mechanism employed is preferably constructed and operated substantially in accordance with the disclosure of m Patent No. 1,369,371, of Feb. 22, 1921. The eft-hand clamp-foot 20, Fig. 7, has pivotally mounted thereon the usual thread- I Cooperate, respectively, with the ledger-blade 78 and slightly resilient bar 79 to cut and nip the needle-thread. The blades 76 77 are operated by means of the usual rod 80 to which the spring 81 is connected to pull it rearwardly or from full to dotted line position, Fig. 8, to carry the blades 76, 77, into cooperative relation with the ledger-blade 78 and bar 79 to sever and nip the needle- ;thread. The rod 80 carries a latch-pin 82 which is engaged by the notched front end of the spring-pressed latch-lever 83 to hold the rod 80 in the' position shown in full lines in Figs. 7 and 8. When the latch 83 is tripped, the upper thread cutter and nipper operates under the influence of the spring 81 to cut and nip theneedle-thread.

Mechanism such as disclosed in my said Patent No. 1,369,371 is preferably provided for pushing the rod 80 forwardly to effect the release of the needle-thread during the at 90 to the tension release lever 91.

sewing of the initial stitches and in time for the beginning end of said thread to be drawn 'down substantially flush with the work by the act'o'n of the stitch-forming instrumentalities. This mechanism comprises the cam 84, Fig. 1, which rotates continuously during the sewing, and the cam-actuated lever 85, 86,fulcrumed at 87, together with the endwise movable latch-pin 88 which is carried by the lever arm and is ejected by the cam 84 after the lever 85, 86, has performed its function of setting the cutting and nipping blades 76, 77, in open POSIEiOIl and thus releasing the beginning needle-thread end.

The latch 83 is tripped by a connection with the sewing mechanism stop-motion device at the end of the sewing period, before the work-holder is shifted away from sewing position, by means of the vertical bar 89 which is pivotally connected at its upper end The bar, 89 is guided in its motion by being slotted at 91 and confined to slide vertically by the headed screw 92 which passes freely through. the slot 91 and into the bracket-arm 3. The bar 89 terminates at its lower end in a foot 93 beneath which the angularextension 94 of the latch-lever 83 is positioned at the end of the sewing period, Figs. 7 and 8. The upperthread tension device 95 and its release ever 91 are of usual construction represented in, my Patent No.. 1,346,102, of July v13, 1920; the lever 91 being operated from the teeth 57 of the stop-motion device through the usual connections represented in my said reissued patent. Such connections include the link 96, lever 97, and threearmed latch-lever 98 mounted on the vertical link 99 connected at its upper end to the lever 91, all .cooperating in the manner disclosed in my said reissued patent.

- The cutter-shaft 56 has mounted thereon .a camlOO such as disclosed in my copendl I i May 5,1922," which actuates the T-shaped lever 101, after the buttonhole has been cut,

and as the cutter-levers are being retracted, to pushthe arm 32 of the clamp-spreading toggle device 31 forwardly and thus spread the work-clamp. The controlling wheel 38 carries a tooth 102, Fig. 2, which engages the follower 103 carried at thelower end of the lever 104 to rock the latter about its fixed pivot 105 and, through the link 1065,

actuatcs the rock-lever 107 and the push-rod 108 which'latter rigidly carries the depending arm 109. The push-rod 108,engag cs the arm 30 of the work-clamp and moves the latter to the position shown in Fig. 2 to open the work-clamp. At the same time the arm 109 engages the free end of the lever 33 and pushes it forwardly to unspread the workclamp. The tooth 102 on the controlling wheel engages the follower 103 just before the machine comes to rest with the parts in the positions shown in Fig. 2.

When sewing a fly-bar buttonhole under the usual conditions obtaining in prior buttonhole sewing machines, it isfound that there is a tendency for the purl of the over the purl gives an undesirable appearance to the finished buttonhole. I have discovered that by providing means for increasing the tension on the under thread while sewing the overlyingfiy-bar stitches, the purl of such stitches may be drawn over to the curved needlc-pathand the desirable uniformity in the stitching preserved throughout the buttonhole.

Such means may conveniently comprise the fork-111 which is adapted to press directly upon one of the disks of the under' thread tension device 115 and is mounted on the rock-shaft 112 journaled in the bearing lugs 113 on the stationary supporting plate 114 for said under thread tension device. Secured to the rock-shaft 112 is the arm 116 to the rearward end of which is' se cured the plate 117 having at its upper end a hole 118 for attachment of one end of the auxiliary tension spring 119, the other end of which is anchored to the adjustable pin 120. The plate 117 is forked at its lower end to embrace the necked front end of the push-pin 121 the rearward end of which bears upon the cam-wheel 122 fixed to the rapid-feed shaft 39. The pm 121 is slidably mounted in the bushing 123 secured to the machine frame. The major portion of the periphery of the cam-wheel 122 is circular and holds the pin 121 pressed forwardly so that the spring 119 cannot press the fork 111 upon the tension-disks 115.

When sewingthe overlying stitches of the fly-bar or the stitches between the points a and b, Fig. 20, the cut-away portion 124 of the cam 122 encounters the pin 121 and is of a depth'such that the spring 119 is free to exert its predetermined pressure through the fork 111 upon the tension disks 115, in addition to the pressure of the usual tension spring 125. By thus automatically increasing t e tension on the'under thread a predetermined amount during the sewing of the needle-punctures and the finished button 1 overlying fly-bar stitches, I have found that the purl will be drawn over to the slit-stitch hole will appear asinFig. 20.

v The under thread "and vcoi'd-c utter is in many respects similar to that disclosed in my said copending application Serial No. 523,056. The present mechanism is, however, simpler in "construction and is actuated independently of the buttonhole cutting mechanism so as not to be limited in its application to machines which cut the buttonhole after sewing. .The present underthread and cord-cutter comprises the scissors device including the ledger-blade 126 and cuttin blade 127 ivoted at 128 to the ledger-bla e. The le ger-blade is secured to the carrier-lever 129 pivoted at 130 to the frontwallof the turret casing 131. The

cutting blade 127 has a tail which carries the follower stud 132 operating in the stationary cam-slot 133. The cam-slot 133 is concentric with the pivot 130 of the'thread-cutter carrying lever 129 throughout the major portion of its lengthbut isformed at its up.-

per end with an offset 134 which operates to close the scissors device after the latter reaches cutting position. The carrier-lever 129 is connected by the link 134 to the front end of the lever 135 fulcrumed at 136 to the bracket 137 on the'mac'hine bed. The rear end of the lever 135 carries a follower roll 138entering the cam-groove 139 in the cam 122 fixed to the rapid-feed shaft 39.

The scissors device is timed to operate after the work-holder has been shifted rearwardly from sewing osition a sutficient distance to effect the u ling of. the last needle-loop clear of the ooper 8 and the pulling off of suflicient lengths of under thread.

thread-cutting position, pulls down the end I of needle-thread and draws the last needle- 1 loop clear of the under thread mechanism. Hence no. needle-loop grippersuch as shown 1n my said copending application Serial No. 523,056 is required to clear the under threadmechanism of the last needle-loop.

The present machine is preferably provided with a cord-nipper to arrest the feed of the cord during the sewing of the initial stitches, so that the initialstitches will be slid along the cord until the'first istitch is even with the endo'f the cord, whereuponthe nipper is opened to allow the cord to run from the supply.- The cord-nipper may. conveniently be made-up in the form of a lever 140pivoted at 141 to a lug 141'- on the machine bed. The lever 140 is formed between its ends with a cam-follower projection 142 adapted to be engaged by the cam sections 143 adjustably secured in the circular groove 144 in theinner face of the controlling wheel 38 by screws 145 which pass through slots .146 in the controlling wheel 38. The lever 140 has slidably mounted transversely of its free end a pin 147, the'outer end of which is backed .up by the adjustable leaf spring 148 secured to the lever 140 by the holding screw 149. and adjusting. screw 150. The free end of the pin 147 is adapted to yieldingly nip the cord against the anvil surface 151 at a gap in the-cord-guiding tube 152. One of the cam sections 143 operates to close the cord-nipper when the initial stitches are being sewed and the other cam section 143 operates to close the nipper during the action of the under thread-cutter to insure against overfeedin of the cord and to hold the cord against de ection during the cutting operation.

' Operation.

The construction and operation of various parts of the machine not hereinbefore re- I ferred to are not novel per se and are shown and described in my said prior patents and copending applications,

. The, operator presses upon the finger-release 153 which through the usual connections described in my said copending application Serial No. 537,381, effects the release of the slide-pin 28 and the coupling for one revolution only of the clamp-closing lever 26 with the cam-groove 154, Fig. 5, in the continuously runmng pulley 29. The clampclosing lever on its return movement'operates as usual through the bar 155 to trip the buttonhole cutter clutch-controlling lever 68 and effect the coupling ofthe cutter-shaft 56 for one revolution only with the continuously running pulley 29. The cutter-shaft efiects, in the order named, the cutting of the buttonhole in the position shown in Fig. 14, the

spreading of the buttonhole and the trip ing' ofthe latch 47 to couple .the rapid-feed s aft 39 to its driver 42 to effect the rapid shift of the out buttonhole from buttonhole cutting position, Fig. 14, to sewing position, F ig. 15.

Just before the stitch-forming mechanism is started the cord-nipper 147 is closed. As the curved needle 7 makes its first up-stroke, Fig. 15, it pulls back the end 156 of the under thread from the position shown in Fig. 14 to that shown in Fig. 15. The straight needle 5 passes through the loop presented by the curved needle and as it rises from lts first descent the lever 85, 86, is operated to open and set the upper thread-nipping and cutting blades; releasing the needle-thread end in time for it to be drawn down flush with the work.

As the initial stitches are formed the end 156 of under thread is drawn back flush with the under surface of the work as shown in Fig. 16. When the initial stitches 157,

Fig. 16, are even with the end of the cord, the cord-nipper 147 is opened and the sewing proceeds in the usual manner around the buttonhole; the under thread tension being auto.- matically increased by the action of the camcontrolled spring-pressed lever 111 when sewing the overlying stitches of the fly-bar to draw the pur over to the curved needle punctures.

When the sewing is completed. the action of the stop-motion device releases the needlethread cutting and nipping blades 76, 77 which nip and sever the needle-thread, as shown in Fig. 17, while the work-clamp is still in sewin position.

The rapideed is also tripped into action through the lifting of the arm 53 by connection with the stopping tooth 57 and the work-clamp is rapidly shifted rearwardly from sewing position to thread-cutting position, Fig. 18. This motion of the workclamp draws out from the needle-throat 18 safe lengths of under thread and cord for the beginning of the next sewing operation and also draws the last needle-loop 158, Fig. 17, clear of the looper 8, as shown in Fig. 18. The cord is again nipped and the scissors device 126, 127 projected to opera tive position to sever the end of needlethrea-d, the under thread and the cord close to the end of the buttonhole. As the scissors device 126, 127, is retracted the workclamp is fed forwardly from thread-cutting to buttonhole cutting or initial position,

whereupon it is unspread and opened to release the work, Fig. 19, by the action of the cam 102 carried by the external controlling wheel 38. When the work is removed, safe ends of cord and under thread remain sticking out of the needle-throat.

The invention is not to be understood as limited to the particular form and arrangement of parts shown and described, as many modifications thereof within the scope of the appended claims will be obvious to those skilled in the art. I

spring tension device for the under thread,

Having thus set forth the nature of the invention, what I claim herein is 1. A buttonhole sewing machine having, in combination, stitch-forming devices, a" work-holder, a stay cord-guide, a cord-nipper, a cord-cutter, a readily accessible controlling wheel andcam means on said controlling wheel and connections for controlling the period. of operation of the stitchforming devices and for operating said cordnipper to arrest the feed of the cord during :lhei sewing of the initial stitches of a button- 2. A buttonhole sewing machine having, in combination, stitch-forming devices including an upper depth-stitch needle and an under curved slit-stitch needle cooperating to sew a purled overseam' a workholder, means for relatively moving the stitch-forming devices and work-holder to sew a fly-bar buttonhole, an under thread tension device, and automatic means for increasing the tension of the under thread tension device while sewin the finishing stitches at the end of a flyar buttonhole, thereby causing the purll) to'be drawn overto the edge of the yar.

3. A buttonhole sewing machine having, in combination, stitch-forming devices including an upper depth-stitch needle and an under curved slit-stitch needle cooperating to sew a purled overseam, a cord-guide, a work-holder, means for relatively moving the stitch-forming devices and work-holder to sew a fly-bar. buttonhole, an under thread tension device, a spring and connectionsfor increasing the tension on the under thread a predetermined amount during the sewing of the overlying fly-bar stitches, and automatic means for controlling the action of said 105 spring.

4. In a buttonhole sewing machine, stitchforming devices including upper thread mechanism and under thread mechanism, a '0 a spring-pressed "auxiliary element acting under its spring pressure to increase the tension of saidtension device a predetermined amount, and a cam and connections for holding said spring-pressed element ineffective in opposition to its spring, said cam having a depression premitting said spring-pressed element to increase the tension. of said tension device. a

5. A buttonhole sewing machinehaving, in combination, a hollow frame, stitch-form- 'ing devices, a work-clamp, clamp-closing ing devices, a Work-clamp, clamp-spreading means, a readily accessible controlling wheel mounted externally of said hollow frame, and cam means on said controlling wheel and connections for controlling the period of action of the stitch-forming devices and for unspreading the work-clamp.

7. A buttonhole sewing machine having, in combination, a hollow frame, stitch-forming devices, a work-clamp, clamp-closing and spreading means, a readily accessible controlling Wheel mounted externally of said hollow frame, and cam means on said con trolling Wheel and connections for controlling the period of action of the stitch-forming devices and for opening and unspreading the work-clamp.

In testimony whereof, I have signed my name to this specification. v

EDWARD B. ALLEN.

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